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  • Current perspective of mitochondrial biology in Parkinson's disease
    Neurochem. Int. (IF 3.262) Pub Date : 2018-03-14
    Navneet Ammal Kaidery, Bobby Thomas

    Parkinson's disease (PD) is one of the most common neurodegenerative movement disorder characterized by preferential loss of dopaminergic neurons of the substantia nigra pars compacta and the presence of Lewy bodies containing α-synuclein. Although the cause of PD remains elusive, remarkable advances have been made in understanding the possible causative mechanisms of PD pathogenesis. An explosion of discoveries during the past two decades has led to the identification of several autosomal dominant and recessive genes that cause familial forms of PD. The investigations of these familial PD gene products have shed considerable insights into the molecular pathogenesis of the more common sporadic PD. A growing body of evidence suggests that the etiology of PD is multifactorial and involves a complex interplay between genetic and environmental factors. Substantial evidence from human tissues, genetic and toxin-induced animal and cellular models indicates that mitochondrial dysfunction plays a central role in the pathophysiology of PD. Deficits in mitochondrial functions due to bioenergetics defects, alterations in the mitochondrial DNA, generation of reactive oxygen species, aberrant calcium homeostasis, and anomalies in mitochondrial dynamics and quality control are implicated in the underlying mechanisms of neuronal cell death in PD. In this review, we discuss how familial PD-linked genes and environmental factors interface the pathways regulating mitochondrial functions and thereby potentially converge both familial and sporadic PD at the level of mitochondrial integrity. We also provide an overview of the status of therapeutic strategies targeting mitochondrial dysfunction in PD. Unraveling potential pathways that influence mitochondrial homeostasis in PD may hold the key to therapeutic intervention for this debilitating neurodegenerative movement disorder.

  • Deletion of serine racemase confers D-serine –dependent resilience to chronic social defeat stress
    Neurochem. Int. (IF 3.262) Pub Date : 2018-03-14
    Chao Dong, Ji-Chun Zhang, Qian Ren, Min Ma, Youge Qu, Kai Zhang, Wei Yao, Tamaki Ishima, Hisashi Mori, Kenji Hashimoto

    The N-methyl-D-aspartate receptor (NMDAR) plays a key role in the pathophysiology of depression. Serine racemase (SRR, encoded by Srr) converts L-serine to D-serine, an endogenous co-agonist at the glycine site of the NMDAR. Knock-out (KO) of Srr did not alter behavioral signs of depression compared with wild-type (WT) mice as evaluated by locomotion, tail suspension, forced swimming, and 1% sucrose preference tests. However, chronic social defeat stress (CSDS: 10 days) caused a depression-like phenotype as measured by these same tests in WT mice but not in Srr KO mice, suggesting that decreased D-serine co-agonist activity confers resilience against CSDS. In WT mice, CSDS decreased brain-derived neurotrophic factor (BDNF) expression and phosphorylation/activation of its receptor TrkB in prefrontal cortex (PFC), dentate gyrus (DG), and the CA3 region of the hippocampus, but increased BDNF and phosphorylated TrkB in the nucleus accumbens (NAc). Conversely, CSDS did not alter BDNF or TrkB phosphorylation in any brain region of Srr KO mice. Administration of D-serine through drinking water (600 mg/L for 20 days) 10 days prior to and during CSDS restored the depression-like phenotype in Srr KO mice. These findings suggest that reducing brain D-serine may improve stress resilience, thereby reducing depression risk.

  • X-ray irradiation induces disruption of the blood–brain barrier with localized changes in claudin-5 and activation of microglia in the mouse brain
    Neurochem. Int. (IF 3.262) Pub Date : 2018-03-12
    Yukari Yoshida, Yukihiko Sejimo, Masashi Kurachi, Yasuki Ishizaki, Takashi Nakano, Akihisa Takahashi

    X-ray irradiation (X-irradiation) induces disruption of the blood–brain barrier (BBB). However, the mechanisms underlying the permeability changes are unclear. Therefore, in the present study, we examined the cellular and molecular changes produced by X-irradiation of the brain. Male ICR mice were irradiated locally on their head, posterior to the bregma, except for the eyes, with a single dose of 60 Gy. BBB permeability was assessed using Evans blue dye. We also examined vascular endothelial growth factor (VEGF) expression, microglial morphology, and the expression of the tight junction protein claudin-5 from 0.5 to 7 days after irradiation. An increase in BBB permeability and a decrease in the expression of VEGF protein occurred in a time-dependent manner. In addition, the number of activated microglia (CD68+/Iba-1+ double-positive cells), the amount of tumor necrosis factor (TNF)-α protein and immunoreactivity of NF-κB increased by irradiation, while the expression of claudin-5 on vascular endothelial cells diminished markedly in the cerebral cortex starting 0.5 days after irradiation. These results suggest that the downregulation of claudin-5 expression mediated by activated microglia may contribute to the BBB disruption induced by X-irradiation.

  • Neuromuscular synapse degeneration without muscle function loss in the diaphragm of a murine model for Huntington's Disease
    Neurochem. Int. (IF 3.262) Pub Date : 2018-03-10
    Priscila A.C. Valadão, Matheus P.S.M. Gomes, Bárbara C. Aragão, Hermann A. Rodrigues, Jéssica N. Andrade, Rubens Garcias, Julliane V. Joviano-Santos, Murilo A. Luiz, Wallace L. Camargo, Lígia A. Naves, Christopher Kushmerick, Walter L.G. Cavalcante, Márcia Gallacci, Itamar C.G. de Jesus, Silvia Guatimosim, Cristina Guatimosim

    Huntington's disease (HD) is an autosomal dominant neurodegenerative disease characterized by chorea, incoordination, and psychiatric and behavioral symptoms. The leading cause of death in HD patients is aspiration pneumonia, associated with respiratory dysfunction, decreased respiratory muscle strength and dysphagia. Although most of the motor symptoms are derived from alterations in the central nervous system, some might be associated with changes in the components of motor units (MU). To explore this hypothesis, we evaluated morphofunctional aspects of the diaphragm muscle in a mouse model of HD (BACHD). We showed that the axons of the phrenic nerves were not affected in 12-months-old BACHD mice, but the axon terminals that form the neuromuscular junctions (NMJs) were more fragmented in these animals in comparison with the wild-type mice. In BACHD mice, the synaptic vesicles of the diaphragm NMJs presented a decreased exocytosis rate. Quantal content and quantal size were smaller and there was less synaptic depression whereas the estimated size of the readily releasable vesicle pool was not changed. At the ultrastructure level, the diaphragm NMJs of these mice presented fewer synaptic vesicles with flattened and oval shapes, which might be associated with the reduced expression of the vesicular acetylcholine transporter protein. Furthermore, mitochondria of the diaphragm muscle presented signs of degeneration in BACHD mice. Interestingly, despite all these cellular alterations, BACHD diaphragmatic function was not compromised, suggesting a higher resistance threshold of this muscle. A putative resistance mechanism may be protecting this vital muscle. Our data contribute to expanding the current understanding of the effects of mutated huntingtin in the neuromuscular synapse and the diaphragm muscle function.

  • Investigating the metabolic alterations in a depressive-like rat model of chronic forced swim stress: An in vivo proton magnetic resonance spectroscopy study at 7T
    Neurochem. Int. (IF 3.262) Pub Date : 2018-03-09
    Chi-Hyeon Yoo, Song-I. Lim, Kyu-Ho Song, Dong-Cheol Woo, Bo-Young Choe

    Although recent investigations of major depressive disorder (MDD) have focused on the monoaminergic system, accumulating evidences suggest that alternative pathophysiological models of MDD and treatment options for patients with MDD are needed. Animals subjected to chronic forced swim stress (CFSS) develop behavioral despair. The purpose of this study was to investigate the in vivo effects of CFSS on systems other than the monoamine system in the rat prefrontal cortex (PFC) with 7T and short-echo-time (16.3 ms) proton magnetic resonance spectroscopy (1H MRS). Ten male Wistar rats underwent 14 days of CFSS, and in vivo1H MRS and forced swim tests were performed before and after CFSS. Point-resolved spectroscopy was used to quantify metabolite levels in the rat PFC. To investigate spectral overlap in glutamate and glutamine, spectral analyses in the spectra obtained in the in vivo1H MRS, parametrically matched spectral simulation, and in vitro experiments were performed. The results of the spectral analyses showed that the glutamate/glutamine spectral overlap was not critical, which suggested that in vivo1H MRS can be used to reliably assess the glutamate system. The rats showed significantly increased immobility times and decreased climbing times in the FST after CFSS, which suggested that the rats developed behavioral despair. The pre-CFSS and post-CFSS glutamate and glutamine levels did not significantly differ (p > 0.050). The levels of myo-inositol, total choline, and N-acetylaspartate, myo-inositol/creatine, and total choline/creatine increased significantly (p < 0.050). Similar findings have been reported in patients with MDD. Taken together, these results suggest that the CFSS-induced metabolic alterations were similar to those found in patients and that high-field and short-echo-time in vivo1H MRS can be used to investigate depression-induced metabolic alterations. Such investigations might provide alternative insights into the nonmonoaminergic pathophysiology and treatment of depression.

  • Tert-butylhydroquinone post-treatment attenuates neonatal hypoxic-ischemic brain damage in rats
    Neurochem. Int. (IF 3.262) Pub Date : 2018-03-09
    Juan Zhang, Lorelei Donovan Tucker, DongYan, Yujiao Lu, Luodan Yang, Chongyun Wu, Yong Li, Quanguang Zhang

    Hypoxic-ischemic (HI) encephalopathy is a leading cause of dire mortality and morbidity in neonates. Unfortunately, no effective therapies have been developed as of yet. Oxidative stress plays a critical role in pathogenesis and progression of neonatal HI. Previously, as a Nrf2 activator, tert-butylhydroquinone (TBHQ) has been demonstrated to exert neuroprotection on brain trauma and ischemic stroke models, as well as oxidative stress-induced cytotoxicity in neurons. It is, however, still unknown whether TBHQ administration can protect against oxidative stress in neonatal HI brain injury. This study was undertaken to determine the neuroprotective effects and mechanisms of TBHQ post-treatment on neonatal HI brain damage. Using a neonatal HI rat model, we demonstrated that TBHQ markedly abated oxidative stress compared to the HI group, as evidenced by decreased oxidative stress indexes, enhanced Nrf2 nuclear accumulation and DNA binding activity, and up-regulated expression of Nrf2 downstream antioxidative genes. Administration of TBHQ likewise significantly suppressed reactive gliosis and release of inflammatory cytokines, and inhibited apoptosis and neuronal degeneration in the neonatal rat cerebral cortex. In addition, infarct size and neuronal damage were attenuated distinctly. These beneficial effects were accompanied by improved neurological reflex and motor coordination as well as amelioration of spatial learning and memory deficits. Overall, our results provide the first documentation of the beneficial effects of TBHQ in neonatal HI model, in part conferred by activation of Nrf2 mediated antioxidative signaling pathways.

  • Glial glutamate transporters expression, glutamate uptake, and oxidative stress in an experimental rat model of intracerebral hemorrhage
    Neurochem. Int. (IF 3.262) Pub Date : 2018-03-09
    J.D. Neves, A. Vizuete, F. Nicola, C. Da Ré, A.F. Rodrigues, F. Schmitz, R.G. Mestriner, D. Aristimunha, A.T. Wyse, C.A. Netto

    Glial glutamate transporters (EAAT1 and EAAT2), glutamate uptake, and oxidative stress are important players in the pathogenesis of ischemic brain injury. However, the changes in EAAT1 and EAAT2 expression, glutamate uptake and the oxidative profile during intracerebral hemorrhage (ICH) development have not been described. The present study sought to investigate the changes of the above-mentioned variables, as well as the Na+/K+- ATPase and glutamine synthetase activities (as important contributors of glutamate homeostasis) and the percentage of neuronal cells after 6 h, 24 h, 72 h and 7 days of ICH. An injection of 0.2U of bacterial collagenase in the ipsilateral striatum was used to induce ICH in male Wistar rats; naïve animals were used as controls. EAAT1 and EAAT2 expression and glutamate uptake in the ipsilateral striatum were assessed. Additionally, the percentage of MAP2+ cells, Na+/K+-ATPase and GS activities, as well as the oxidative profile were analyzed. It is shown a decrease of EAAT1 expression and glutamate uptake 6 h post-ICH, whereas EAAT2 decreased 72 h after the event; conversely EAAT2 and glutamate uptake were increased after 7 days. The oxidative stress and endogenous defense system exhibited a remarkable response at 72 h of injury. ICH also increased Na+/K+-ATPase activity and selectively decreased GS activity, variables known to be important contributors of glial glutamate transporters activities. Altogether, present findings indicate that ICH induces different temporal EAAT1 and EAAT2 responses, culminating with an imbalance of glutamate uptake capacity, increased oxidative stress and sustained neuronal loss.

  • Axon-terminals expressing EAAT2 (GLT-1; Slc1a2) are common in the forebrain and not limited to the hippocampus
    Neurochem. Int. (IF 3.262) Pub Date : 2018-03-09
    Yun Zhou, Bjørnar Hassel, Tore Eid, Niels Christian Danbolt

    The excitatory amino acid transporter type 2 (EAAT2) represents the major mechanism for removal of extracellular glutamate. In the hippocampus, there is some EAAT2 in axon-terminals, whereas most of the protein is found in astroglia. The functional importance of the neuronal EAAT2 is unknown, and it is debated whether EAAT2 expressing nerve terminals are present in other parts of the brain. Here we selectively deleted the EAAT2 gene in neurons (by crossing EAAT2-flox mice with synapsin 1-Cre mice in the C57B6 background). To reduce interference from astroglial EAAT2, we measured glutamate accumulation in crude tissue homogenates. EAAT2 proteins levels were measured by immunoblotting. Although synapsin 1-Cre mediated gene deletion only reduced the forebrain tissue content of EAAT2 protein to 95.5 ± 3.4% of wild-type (littermate) controls, the glutamate accumulation in homogenates of neocortex, hippocampus, striatum and thalamus were nevertheless diminished to, respectively, 54 ± 4, 46 ± 3, 46 ± 2 and 65 ± 7% of controls (average ± SEM, n = 3 pairs of littermates). GABA uptake was unaffected. After injection of U-13C-glucose, lack of neuronal EAAT2 resulted in higher 13C-labeling of glutamine and GABA in the hippocampus suggesting that neuronal EAAT2 is partly short-circuiting the glutamate-glutamine cycle in wild-type mice. Crossing synapsin 1-Cre mice with Ai9 reporter mice revealed that Cre-mediated excision occurred efficiently in hippocampus CA3, but less efficiently in other regions and hardly at all in the cerebellum. Conclusions: (1) EAAT2 is expressed in nerve terminals in multiple brain regions. (2) The uptake catalyzed by neuronal EAAT2 plays a role in glutamate metabolism, at least in the hippocampus. (3) Synapsin 1-Cre does not delete floxed genes in all neurons, and the contribution of neuronal EAAT2 is therefore likely to be larger than revealed in the present study.

  • Neuroprotective potential of spermidine against rotenone induced Parkinson's disease in rats
    Neurochem. Int. (IF 3.262) Pub Date : 2018-03-06
    Sunaina Sharma, Puneet Kumar, Rahul Deshmukh

    Parkinson's disease is a leading hypokinetic disorder characterized by selective loss of dopaminergic neurons in substantia nigra pars compacta (SNpc) region of mid-brain. Degeneration of dopaminergic neurons is considered to be due to oxidative stress, neuroinflammation, disturbed calcium homeostasis and glutamate excitotoxicity etc. Spermidine is a polyamine which counteracts age associated cell death by scavenging free radical formation, activates authophagic machinery by enhancing formation of autophagosome, and antagonizes NMDA receptor. In the current study we investigated the neuroprotective potential of spermidine against rotenone induced PD in rats. Rats were treated subcutaneously with rotenone 1.5 mg/kg daily for 28 days. Spermidine 5&10 mg/kg was administered orally 1 h prior to rotenone administration from 15 to 28. Rotenone caused significant reduction in motor functioning and elevated levels of oxidative stress markers and proinflammatory cytokines levels (IL-1β, IL6 and TNF-α). The neurochemical analysis revealed a significant decrease in serotonin, norepinephrine, dopamine and their metabolites accompanied by a significant loss of dopaminergic neurons in the SNpc following ROT injection. However, treatment with spermidine rescued DAergic neurons in SNpc and nerve terminals in the striatum following ROT insult. Spermidine treatment also attenuated oxidative stress, neuroinflammation and restored striatal neurochemistry. Results of our study suggest that spermidine has promising neuroprotective effect against degenerative changes in experimental PD, and the protective effects are mediated through its antioxidant and anti-inflammatory properties.

  • 1H NMR metabolic signature of cerebrospinal fluid following repetitive lower-limb remote ischemia preconditioning
    Neurochem. Int. (IF 3.262) Pub Date : 2018-02-22
    Hailiang Wang, Zhiyong He, Yijue Zhang, Jun Zhang

    Background Objective The cerebral ischemia/reperfusion greatly influences brain metabolism. Remote ischemia preconditioning (RIPC) is reported to confer neuroprotective effects against cerebral ischemia in animal models and human. This study aims to investigate the metabolomic profiles of cerebrospinal fluid (CSF) in patients treated with repetitive lower limb RIPC and provides an insight into possible mechanism underlying RIPC-induced neuroprotection. Method Fifty healthy patients undergoing minor surgery under spinal anesthesia were randomly allocated to 2 groups: control group (Group C, n = 25) and RIPC treatment group (Group T,n = 25). Repetitive limb RIPC were performed 3 sessions, consisting of three 5-min cycles per session from the day before surgery to the morning on the surgery day. The CSF samples were collected from 48 patients before intrathecal injection of local anesthetic. A proton nuclear magnetic resonance (1H NMR)-based metabonomics approach was used to obtain the CSF metabolic profiles of the samples (n = 24 each). The acquired data were processed with MestReNova and followed by statistical analysis with SIMCA-P. Results The model obtained with the orthogonal partial least-squares discriminant analysis (OPLS-DA) identified difference of metabolite profiles between two groups. The validation of the discriminant analysis showed that the accuracy of the OPLS-DA model was 81.3%. Sixteen metabolites including glucose, amino-acids and organic acids et al. were identified as the most influential CSF biomarkers for the discrimination between two groups, which are involved in pathways of energy metabolism and amino-acids metabolism. Conclusion 1H NMR spectra combined with pattern recognition analysis offers a new and promising platform to investigate metabolic signatures in patients treated with RIPC. Our results suggest repetitive RIPC mainly changes energy metabolism and amino-acid metabolism in brain, which provides a potential mechanistic understanding of RIPC-induced tolerance to cerebral ischemia.

  • Lanthionine ketimine-5-ethyl ester provides neuroprotection in a zebrafish model of okadaic acid-induced Alzheimer's disease
    Neurochem. Int. (IF 3.262) Pub Date : 2018-02-21
    Daniel Koehler, Zahoor A. Shah, Kenneth Hensley, Frederick E. Williams

    Okadaic acid (OKA) is a protein phosphatase-2A inhibitor that is used to induce neurodegeneration and study disease states such as Alzheimer's disease (AD). Lanthionine ketimine-5-ethyl ester (LKE) is a bioavailable derivative of the naturally occurring brain sulfur metabolite, lanthionine ketimine (LK). In previously conducted studies, LKE exhibited neuroprotective and neurotrophic properties in murine models but its mechanism of action remains to be clarified. In this study, a recently established zebrafish OKA-induced AD model was utilized to further elucidate the neuroprotective and neurotrophic properties of LKE in the context of an AD-like condition. The fish were divided into 3 groups containing 8 fish per group. Group #1 = negative control, Group #2 = 100 nM OKA, Group #3 = 100 nM OKA +500 μM LKE. OKA caused severe cognitive impairments in the zebrafish, but concomitant treatment with LKE protected against cognitive impairments. Further, LKE significantly and substantially reduced the number of apoptotic brain cells, increased brain-derived neurotrophic factor (BDNF), and increased phospho-activation of the pro-survival factors pAkt (Ser 473) and pCREB (Ser133). These findings clarify the neuroprotective and neurotrophic effects of LKE by highlighting particular survival pathways that are bolstered by the experimental therapeutic LKE.

  • Astaxanthin protects against kainic acid-induced seizures and pathological consequences
    Neurochem. Int. (IF 3.262) Pub Date : 2018-02-21
    Yi Chang, Cheng Wei Lu, Yi Jing Chen, Tzu Yu Lin, Shu Kuei Huang, Su Jane Wang

    Excitotoxic damage caused by increased glutamate levels is involved in the pathogenesis of neurodegenerative diseases. Astaxanthin, a natural carotenoid with multiple health benefits, inhibits glutamate release from the brain tissue; however, whether it possesses the ability to affect glutamate-induced brain injury is unknown. The present study investigated the neuroprotective effects of astaxanthin on kainic acid (KA)-induced excitotoxicity in rats and the possible underlying intracellular signaling pathway. The rats were orally administrated with astaxanthin (50 or 100 mg/kg) for 7 days (once a day), and KA (15 mg/kg) was administered intraperitoneally at 1 h after the final administration. The results revealed that KA induced seizures, increased the hippocampal glutamate levels, caused considerable neuronal death and microglial activation in the hippocampal CA3 regions, and increased the production of proinflammatory cytokines. Astaxanthin pretreatment prevented these changes. Furthermore, astaxanthin pretreatment increased the expression of neuronal cell survival-related factors, including phosphorylated Akt, phosphorylated glycogen synthase kinase-3β, and Bcl-2 in the hippocampus of KA-injected rats. These results suggested that astaxanthin can attenuate seizures, mitigate inflammation, augment survival signals, and prevent hippocampal neuronal damage in the animal model of KA-induced excitotoxicity.

  • Brain bioenergetics in rats with acute hyperphenylalaninemia ☆
    Neurochem. Int. (IF 3.262) Pub Date : 2018-02-14
    Nádia Weber Dimer, Bruna Klippel Ferreira, Jotele Fontana Agostini, Maria Luiza Gomes, Luiza Wilges Kist, Fernanda Malgarin, Milena Carvalho-Silva, Lara Mezari Gomes, Joyce Rebelo, Marisa Jádna Silva Frederico, Fátima Regina Mena Barreto Silva, Eduardo Pacheco Rico, Mauricio Reis Bogo, Emilio Luiz Streck, Gustavo Costa Ferreira, Patrícia Fernanda Schuck

    Phenylketonuria (PKU) is a disorder of phenylalanine (Phe) metabolism caused by deficient phenylalanine hydroxylase activity. The deficiency results in increased levels of Phe and its metabolites in fluids and tissues of patients. PKU patients present neurological signals and symptoms including hypomyelination and intellectual deficit. This study assessed brain bioenergetics at 1 h after acute Phe administration to induce hyperphenylalaninemia (HPA) in rats. Wistar rats were randomized in two groups: HPA animals received a single subcutaneous administration of Phe (5.2 μmol/g) plus p-Cl-Phe (PAH inhibitor) (0.9 μmol/g); control animals received a single injection of 0.9% NaCl. In cerebral cortex, HPA group showed lower mitochondrial mass, lower glycogen levels, as well as lower activities of complexes I-III and IV, ATP synthase and citrate synthase. Higher levels of free Pi and phospho-AMPK, and higher activities of LDH, α-ketoglutarate dehydrogenase and isocitrate dehydrogenase were also reported in cerebral cortex of HPA animals. In striatum, HPA animals had higher LDH (pyruvate-lactate) and isocitrate dehydrogenase activities, and lower activities of α-ketoglutarate dehydrogenase and complex IV, as well as lower phospho-AMPK immunocontent. In hippocampus, HPA rats had higher mRNA expression for MFN1 and higher activities of α-ketoglutarate dehydrogenase and isocitrate dehydrogenase, but decreased activities of pyruvate dehydrogenase and complexes I and IV. In conclusion, our data demonstrated impaired bioenergetics in cerebral cortex, striatum and hippocampus of HPA rats.

  • Cholinergic tone in ventral tegmental area: Functional organization and behavioral implications
    Neurochem. Int. (IF 3.262) Pub Date : 2018-02-10
    Changzheng Zhang, Xiaodong Liu, Peiling Zhou, Junjie Zhang, Wuming He, Ti-Fei Yuan

    The ventral tegmental area (VTA), a pivotal brain region of the mesocorticolimbic dopaminergic system, is substantially innervated and modulated by cholinergic projections from the pedunculopontine tegmental nucleus and laterodorsal tegmental nucleus. In this review, we focus mainly on the current findings on VTA cholinergic compositions and functions, including VTA cholinergic innervations and synaptic connectivity, acetylcholine receptor expression and functional characteristics, cholinergic modulation of neuronal activity and dopamine efflux, cholinergic modulation of VTA-mediated behaviors such as reward and addiction, stress and depression, locomotion, etc. Taken together, these findings indicate that cholinergic transmission to the VTA plays an important role in modulation of the VTA circuit, which is implicated in regulation of multiple behaviors.

  • Peroxiredoxin-3 attenuates traumatic neuronal injury through preservation of mitochondrial function
    Neurochem. Int. (IF 3.262) Pub Date : 2018-02-08
    Wei Hu, Xing-Bo Dang, Gang Wang, Shuai Li, Yue-Lin Zhang

    Peroxiredoxins (PRDXs) are a highly conserved family of thiol peroxidases that scavenge peroxides in cells. PRDX3 is one member of PRDXs localized in the mitochondria, and has been shown to be involved in antioxidant defense and redox signaling. In this study, we investigated the role of PRDX3 in neuronal trauma using a traumatic neuronal injury (TNI) model in primary cultured cortical neurons. We found that TNI significantly decreased the expression of PRDX3 at both mRNA and protein levels. Overexpression of PRDX3 by lentivirus (LV-PRDX3) transfection attenuated lactate dehydrogenase (LDH) release and neuronal apoptosis after TNI. The results of immunostaining showed that LV-PRDX3 transfection markedly reduced TNI-induced intracellular ROS production, protein radical formation and lipid peroxidation. In addition, overexpression of PRDX3 preserved mitochondrial membrane potential (MMP) levels and ATP generation, and inhibited mitochondrial cytochrome c release in TNI-injured neurons. The results of polymerase chain reaction (PCR) showed that PRDX3 overexpression also increased mitochondrial DNA (mtDNA) content and upregulated the expression of mitochondrial biogenesis-related factors. Taken together, our data demonstrate that PRDX3 protects against TNI insult by preserving mitochondrial function and mitochondrial biogenesis, and may have potential therapeutic value for traumatic brain injury (TBI).

  • 更新日期:2018-02-07
  • Alterations of L-type voltage dependent calcium channel alpha 1 subunit in the hippocampal CA3 region during and after pilocarpine-induced epilepsy
    Neurochem. Int. (IF 3.262) Pub Date : 2018-02-07
    Jie hua Xu, Hui Wang, Wen Zhang, Feng ru Tang

    Voltage-dependent calcium channels (VDCC) have been shown to regulate neuronal excitability and their antagonists have been used clinically for the control of seizures. While functional studies of VDCC in epileptogenesis in the CA1 area of hippocampus or the dentate gyrus have been done, few studies were carried out in the CA3 area. Given the bursting characteristics of the CA3 neurons, we speculated that VDCC in the CA3 area might play an important role in the epileptogenesis. In the present study in the mouse pilocarpine model of temporal lobe epilepsy, we investigated the alterations of alpha 1 subunits of L-type VDCC in the CA3 area of the hippocampus at different stages of epileptogenesis, i.e., acute stage from 10 min to 1 day during and after pilocapine-induced status epilepticus (SE), latent period at 1 week, and chronic stage with spontaneous recurrent seizures at 2 months after SE. We found that an immediate redistribution of alpha 1 subunits in the CA3 area occurred during SE which might be involved in the seizure occurrence indicated by the Racine score record. Alterations of alpha 1 subunits were also demonstrated in the latent period and chronic stage, which might be related to the epileptogenesis and occurrence of epilepsy. Cav1.3, but not Cav1.2, was expressed in reactive astrocytes of the CA3 area, indicating the involvement of Cav1.3 in the modulation of astrocytic Ca2+ homeostasis during epileptogenesis.

  • New roles of reactive astrocytes in the brain; an organizer of cerebral ischemia
    Neurochem. Int. (IF 3.262) Pub Date : 2018-02-02
    Schuichi Koizumi, Yuri Hirayama, Yosuke M. Morizawa

    The brain consists of neurons and much higher number of glial cells. They communicate each other, by which they control brain functions. The brain is highly vulnerable to several insults such as ischemia, but has a self-protective and self-repairing mechanisms against these. Ischemic tolerance or preconditioning is an endogenous neuroprotective phenomenon, where a mild non-lethal ischemic episode can induce resistance to a subsequent severe ischemic injury in the brain. Because of its neuroprotective effects against cerebral ischemia or stroke, ischemic tolerance has been widely studied. However, almost all studies have been performed from the viewpoint of neurons. Glial cells are structurally in close association with synapses. Recent studies have uncovered the active roles of astrocytes in modulating synaptic connectivity, such as synapse formation, elimination and maturation, during development or pathology. However, glia-mediated ischemic tolerance and/or neuronal repairing have received only limited attention. We and others have demonstrated that glial cells, especially astrocytes, play a pivotal role in regulation of induction of ischemic tolerance as well as repairing/remodeling of neuronal networks by phagocytosis. Here, we review our current understanding of (1) glial-mediated ischemic tolerance and (2) glia-mediated repairing/remodeling of the penumbra neuronal networks, and highlight their mechanisms as well as their potential benefits, problems, and therapeutic application.

  • A role for KCC3 in maintaining cell volume of peripheral nerve fibers
    Neurochem. Int. (IF 3.262) Pub Date : 2018-01-31
    Bianca Flores, Cara C. Schornak, Eric Delpire

    The potassium chloride cotransporter, KCC3, is an electroneutral cotransporter expressed in the peripheral and central nervous system. KCC3 is responsible for the efflux of K+ and Cl− in neurons to help maintain cell volume and intracellular chloride levels. A loss-of- function (LOF) of KCC3 causes Hereditary Motor Sensory Neuropathy with Agenesis of the Corpus Callosum (HMSN/ACC) in a population of individuals in the Charlevoix/Lac-Saint-Jean region of Quebec, Canada. A variety of mouse models have been created to understand the physiological and deleterious effects of a KCC3 LOF. Though this KCC3 LOF in mouse models has recapitulated the peripheral neuropathy phenotype of HMSN/ACC, we still know little about the development of the disease pathophysiology. Interestingly, the most recent KCC3 mouse model that we created recapitulated a peripheral neuropathy-like phenotype originating from a KCC3 gain-of-function (GOF). Despite the past two decades of research in attempting to understand the role of KCC3 in disease, we still do not understand how dysfunction of this cotransporter can lead to the pathophysiology of peripheral neuropathy. This review focuses on the function of KCC3 in neurons and its role in human and health and disease.

  • S-oxiracetam ameliorates ischemic stroke induced neuronal apoptosis through up-regulating α7 nAChR and PI3K / Akt / GSK3β signal pathway in rats
    Neurochem. Int. (IF 3.262) Pub Date : 2018-01-19
    Wenxiang Fan, Xiang Li, Liangliang Huang, Shucheng He, Zhicheng Xie, Yuxin Fu, Weirong Fang, Yunman Li

    Ischemic stroke, the main reason for severe disabilities in the world, is associated with a high incidence of sensorimotor and cognitive dysfunction. In this study, we use the middle cerebral artery occlusion/reperfusion (MCAO/R) model in rats and oxygen glucose deprivation/reoxygenation (OGD/R) model in fetal rat primary cortical neurons to investigate whether and how S-oxiracetam (S-ORC) protect brain injury from ischemic stroke. The results revealed that S-ORC reduced brain infarct size and lessened neurological dysfunction after stroke. Further study demonstrated that S-ORC diminished TUNEL positive cells, increased cell viability, decreased LDH activity, and inhibited cell apoptotic rate. Furthermore, S-ORC inhibited neuronal apoptosis by activating the PI3K/Akt/GSK3β signaling pathway via α7 nAChR, which was evidenced by α7 nAChR siRNA. In conclusion, our findings strongly suggest that S-ORC could be used as an effective neuroprotective agent for ischemic stroke due to its effect in preventing neuronal apoptosis.

  • Dipeptidyl peptidase IV, which probably plays important roles in Alzheimer disease (AD) pathology, is upregulated in AD brain neurons and associates with amyloid plaques
    Neurochem. Int. (IF 3.262) Pub Date : 2018-01-17
    Hans-Gert Bernstein, Henrik Dobrowolny, Gerburg Keilhoff, Johann Steiner

    There is evidence from in vitro experiments that dipeptidyl peptidase IV (DPP IV) might play role(s) in amyloid formation. However, nothing is known about the localization of the enzyme in brains of individuals with Alzheimer's disease. We herein show that in comparison to non-demented controls DPP IV is upregulated in AD brain neurons and occurs in multiple amyloid plaques.

  • Nicotine alleviates chronic stress-induced anxiety and depressive-like behavior and hippocampal neuropathology via regulating autophagy signaling
    Neurochem. Int. (IF 3.262) Pub Date : 2018-01-16
    Xi Xiao, Xueliang Shang, Baohui Zhai, Hui Zhang, Tao Zhang

    Recently, we reported that chronic nicotine significantly improved chronic stress-induced impairments of cognition and the hippocampal synaptic plasticity in mice, however, the underlying mechanism still needs to be explored. In the present study, 32 male C57BL/6 mice were divided into four groups: control (CON), stress (CUS), stress with chronic nicotine administration (CUS + Nic) and chronic nicotine administration (Nic). The anxiety-like behavior and neuropathological alteration of DG neurons were examined. Moreover, PC12 cells were examined with corticosterone in the presence or absence of nicotine. Both cell viability and apoptosis were determined. When treated simultaneously with an unpredictable chronic mild stress (CUS), nicotine (0.2 mg/kg/d) attenuated behavioral deficits and neuropathological alterations of DG neurons. Moreover, Western blotting showed that chronic nicotine also elevated the level of autophagy makers including Beclin-1 and LC3 II triggered by CUS. In addition, concomitant treatment with nicotine (10 μM) significantly attenuated the loss of PC12 cell viability (p < .01) and apoptosis compared to that of corticosterone treatment alone. Besides, chronic nicotine also enhanced the protein and RNA expression levels of autophagy makers triggered by corticosterone, such as Beclin-1, LC3 II and p62/SQSTM1. However, the above improvements were significantly blocked by autophagy inhibitor 3-MA. Importantly, the activation of the PI3K/Akt/mTOR signaling was carefully tested to illuminate the effects of chronic nicotine. Consequently, chronic nicotine played a role of neuroprotection in either CUS mice or corticosterone cells associating with the enhancement of the autophagy signaling, which was involved in activating the PI3K/Akt/mTOR signaling.

  • Curcumin potentiates the function of human α7-nicotinic acetylcholine receptors expressed in SH-EP1 cells
    Neurochem. Int. (IF 3.262) Pub Date : 2018-01-16
    Eslam El Nebrisi, Lina T. Al Kury, Keun-Hang Susan Yang, Petrilla Jayaprakash, Frank C. Howarth, Nadine Kabbani, Murat Oz

    Effects of curcumin, a biologically active ingredient of turmeric, were tested on the Ca2+ transients induced by the activation of α7 subunit of the human nicotinic acetylcholine (α7 nACh) receptor expressed in SH-EP1 cells. Curcumin caused a significant potentiation of choline (1 mM)-induced Ca2+ transients with an EC50 value of 133 nM. The potentiating effect of curcumin was not observed in Ca2+ transients induced by high K+ (60 mM) containing solutions or activation of α4β2 nACh receptors and the extent of curcumin potentiation was not altered in the presence of Ca2+ channel antagonists nifedipine (1 μM), verapamil (1 μM), ω-conotoxin (1 μM), and bepridil (10 μM). Noticeably the effect of curcumin was not observed when curcumin and choline were co-applied without curcumin pre-incubation. The effect of curcumin on choline-induced Ca2+ transients was not reversed by pre-incubation with inhibitors of protein C, A, and CaM kinases. Metabolites of curcumin such as tetrahydrocurcumin, demethylcurcumin, and didemethylcurcumin also caused potentiation of choline-induced Ca2+ transients. Notably, specific binding of [125I]-bungarotoxin was not altered in the presence of curcumin. Collectively, our results indicate that curcumin allosterically potentiate the function of the α7-nACh receptor expressed in SH-EP1 cells.

  • CDC42EP4, a perisynaptic scaffold protein in Bergmann glia, is required for glutamatergic tripartite synapse configuration
    Neurochem. Int. (IF 3.262) Pub Date : 2018-01-09
    Natsumi Ageta-Ishihara, Kohtarou Konno, Maya Yamazaki, Manabu Abe, Kenji Sakimura, Masahiko Watanabe, Makoto Kinoshita

    Configuration of tripartite synapses, comprising the pre-, post-, and peri-synaptic components (axon terminal or bouton, dendritic spine, and astroglial terminal process), is a critical determinant of neurotransmitter kinetics and hence synaptic transmission. However, little is known about molecular basis for the regulation of tripartite synapse morphology. Previous studies showed that CDC42EP4, an effector protein of a cell morphogenesis regulator CDC42, is expressed exclusively in Bergmann glia in the cerebellar cortex, that it forms tight complex with the septin heterooligomer, and that it interacts indirectly with the glutamate transporter GLAST and MYH10/nonmuscle myosin ΙΙB. Scrutiny of Cdc42ep4-/- mice had revealed that the CDC42EP4-septins-GLAST interaction facilitates glutamate clearance, while the role for CDC42EP4-septins-MYH10 interaction has remained unsolved. Here, we find anomalous configuration of the tripartite synapses comprising the parallel fiber boutons, dendritic spines of Purkinje cells, and Bergmann glial processes in Cdc42ep4-/- mice. The complex anomalies include 1) recession of Bergmann glial membranes from the nearest active zones, and 2) extension of nonactive synaptic contact around active zone. In line with the recession of Bergmann glial membranes by the loss of CDC42EP4, overexpression of CDC42EP4 in heterologous cells promotes cell spreading and partitioning of MYH10 to insoluble (i.e., active) fraction. Paradoxically, however, Cdc42ep4-/- cerebellum contained significantly more MYH10 and N-cadherin, which is attributed to secondary neuronal response mainly in Purkinje cells. Given cooperative actions of N-cadherin and MYH10 for adhesion between neurons, we speculate that their augmentation may reflect the extension of nonactive synaptic contacts in Cdc42ep4-/- cerebellum. Transcellular mechanism that links the absence of CDC42EP4 in Bergmann glia to the augmentation of N-cadherin and MYH10 in neurons is currently unknown, but the phenotypic similarity to GLAST-null mice indicates involvement of the glutamate intolerance. Together, the unique phenotype of Cdc42ep4-/- mice provides a clue to novel molecular network underlying tripartite synapse configuration.

  • Research progress in stroke-induced immunodepression syndrome (SIDS) and stroke-associated pneumonia (SAP)
    Neurochem. Int. (IF 3.262) Pub Date : 2018-01-06
    Dan-Dan Liu, Shi-Feng Chu, Chen Chen, Peng-Fei Yang, Nai-Hong Chen, Xin He

    In recent years, stroke-induced immunodepression syndrome (SIDS) and the resulting stroke-associated infection (SAI) have become a focus of current research efforts. Inflammatory reactions after stroke promote tissue healing and eliminate necrotic cells, whereas excessive inflammatory reactions may cause secondary damage. Stroke-induced immunodepression not only reduces inflammatory reactions and protects brain tissues but also weakens the resistance of the human body against pathogens and leads to infection. Changes in the local and systemic immune system in stroke patients may play an important role in prognosis. Infection is a leading cause of death in patients following stroke, and an evaluation of the prognosis of stroke patients is associated closely with the presence of infectious complications. Among these complications, pneumonia is the most common type of infection observed after acute stroke, which exhibits the greatest effect on the recovery of neurological function. SIDS is closely related to stroke-associated pneumonia (SAP), and the use of immunodepression as an entry point may provide an efficacious treatment target and drug development strategy. An improved understanding of the pathophysiological mechanisms leading to SAP is essential to develop new treatment strategies for improving the outcomes of stroke patients.

  • Circadian modification network of a core clock driver BMAL1 to harmonize physiology from brain to peripheral tissues
    Neurochem. Int. (IF 3.262) Pub Date : 2018-01-03
    Teruya Tamaru, Ken Takamatsu

    Circadian clocks dictate various physiological functions by brain SCN (a central clock) -orchestrating the temporal harmony of peripheral clocks of tissues/organs in the whole body, with adaptability to environments by resetting their timings. Dysfunction of this circadian adaptation system (CAS) occasionally causes/exacerbates diseases. CAS is based on cell-autonomous molecular clocks, which oscillate via a core transcriptional/translational feedback loop with clock genes/proteins, e.g., BMAL1: CLOCK circadian transcription driver and CRY1/2 and PER1/2 suppressors, and is modulated by various regulatory loops including clock protein modifications. Among mutants with a single clock gene, BMAL1-deficient mice exhibit the most drastic loss of circadian functions. Here, we highlight on numerous circadian protein modifications of mammalian BMAL1, e.g., multiple phosphorylations, SUMOylation, ubiquitination, acetylation, O-GlcNAcylation and S-nitrosylation, which mutually interplay to control molecular clocks and coordinate physiological functions from the brain to peripheral tissues through the input and output of the clocks.

  • Nicotinic acetylcholine receptor (nAChR) mediated dopamine release in larval Drosophila melanogaster
    Neurochem. Int. (IF 3.262) Pub Date : 2018-01-03
    Poojan Pyakurel, Mimi Shin, B. Jill Venton
  • Pathological role of lipid interaction with α-synuclein in Parkinson's disease
    Neurochem. Int. (IF 3.262) Pub Date : 2018-01-03
    Mari Suzuki, Kazunori Sango, Keiji Wada, Yoshitaka Nagai

    Alpha-synuclein (αSyn) plays a central role in the pathogenesis of Parkinson's disease (PD) and dementia with Lewy bodies (DLB). In sporadic PD and DLB, normally harmless αSyn proteins without any mutations might gain toxic functions by unknown mechanisms. Thus, it is important to elucidate the factors promoting the toxic conversion of αSyn, towards understanding the pathogenesis of and developing disease-modifying therapies for PD and DLB. Accumulating biophysical and biochemical studies have demonstrated that αSyn interacts with lipid membrane, and the interaction influences αSyn oligomerization and aggregation. Furthermore, genetic and clinicopathological studies have revealed mutations in the glucocerebrosidase 1 (GBA1) gene, which encodes a degrading enzyme for the glycolipid glucosylceramide (GlcCer), as strong risk factors for PD and DLB, and we recently demonstrated that GlcCer promotes toxic conversion of αSyn. Moreover, pathological studies have shown the existence of αSyn pathology in lysosomal storage disorders (LSDs) patient’ brain, in which glycosphingolipids (GSLs) is found to be accumulated. In this review, we focus on the lipids as a key factor for inducing wild-type (WT) αSyn toxic conversion, we summarize the knowledge about the interaction between αSyn and lipid membrane, and propose our hypothesis that aberrantly accumulated GSLs might contribute to the toxic conversion of αSyn. Identifying the trigger for toxic conversion of αSyn would open a new therapeutic road to attenuate or prevent crucial events leading to the formation of toxic αSyn.

  • A refined concept: Alpha synuclein dysregulation disease
    Neurochem. Int. (IF 3.262) Pub Date : 2018-01-02
    Hideki Mochizuki, Chi-Jing Choong, Eliezer Masliah

    Alpha synuclein (αSyn) still remains a mysterious protein even two decades after SNCA encoding it was identified as the first causative gene of familial Parkinson's disease (PD). Accumulation of αSyn causes α-synucleinopathies including PD, dementia with Lewy bodies (DLB) and multiple system atrophy (MSA). Recent advances in therapeutic approaches offer new antibody-, vaccine-, antisense-oligonucleotide- and small molecule-based options to reduce αSyn protein levels and aggregates in patient's brain. Gathering research information of other neurological disease particularly Alzheimer's disease, recent disappointment of an experimental amyloid plaques busting antibody in clinical trials underscores the difficulty of treating people who show even mild dementia as damage in their brain may already be too extensive. Prodromal intervention to inhibit the accumulation of pathogenic protein may advantageously provide a better outcome. However, treatment prior to onset is not ethically justified as standard practice at present. In this review, we initiate a refined concept to define early pathogenic state of αSyn accumulation before occurrence of brain damage as a disease criterion for αSyn dysregulation disease.

  • Coronaridine congeners modulate mitochondrial α3β4* nicotinic acetylcholine receptors with different potency and through distinct intra-mitochondrial pathways
    Neurochem. Int. (IF 3.262) Pub Date : 2017-12-23
    Hugo R. Arias, Olena Lykhmus, Kateryna Uspenska, Maryna Skok

    In contrast to plasma membrane-expressed nicotinic acetylcholine receptors (nAChRs), mitochondrial nAChRs function in an ion-independent manner by triggering intra-mitochondrial kinases that regulate the release of cytochrome c (Cyt c), an important step in cellular apoptosis. The aim of this study is to determine the structural requirements for mitochondrial α3β4* nAChR activation by measuring the modulatory effects of two noncompetitive antagonists of these receptors, (+)-catharanthine and (±)-18-methoxycoronaridine [(±)-18-MC], on Cyt c release from wild-type and α7-/- mice mitochondria. The sandwich ELISA results indicated that α3β4* nAChRs are present in liver mitochondria in higher amounts compared to that in brain mitochondria and that these receptors are up-regulated in α7-/- mice. Correspondingly, (±)-18-MC decreased Cyt c release from liver mitochondria of wild-type mice and from brain and liver mitochondria of α7-/- mice. The effect in wild-type mice mitochondria was mediated mainly by the Src-dependent pathway, regulating the apoptogenic activity of reactive oxygen species, while in α7-/- mice mitochondria, (±)-18-MC strongly affected the calcium-calmodulin kinase II-dependent pathway. In contrast, (+)-catharanthine was much less potent than (±)-18-MC and triggered several signaling pathways, suggesting the involvement of multiple nAChR subtypes. These results show for the first time that noncompetitive antagonists can induce mitochondrial α3β4* nAChR signaling, giving a more comprehensive understanding on the function of intracellular nAChR subtypes.

  • The release and transmission of amyloid precursor protein via exosomes
    Neurochem. Int. (IF 3.262) Pub Date : 2017-12-23
    Tingting Zheng, Xiaoqing Wu, Xiaojie Wei, Mingkai Wang, Baorong Zhang

    Amyloid precursor protein (APP) processing is central in Alzheimer's disease (AD) pathogenesis. The healthy unaffected neurons suffer the transmission of amyloid protein from pathologically affected neurons, which may play an important role in the anatomical spread of the disease. Exosomes are appropriate candidates for transmission of amyloid species, because of their potential role as “intercellular transportation”. To address a role of secreted exosomes in neuronal homeostasis in AD, we harvested exosomes from the conditioned medium of HEK293-APP Swe/Ind cells. We have demonstrated that these exosomes contained APP and were capable of efficiently transferring APP to normal primary neurons. Moreover, these exosomes had dose-dependent detrimental effect on cultured neurons. Our results suggest a key mechanism underlying the spread of amyloid protein in the brain and the acceleration of pathology in AD; exosomes secretion serves to amplify and propagate Alzheimer's disease related pathology.

  • High-fat diet-induced hyperglutamatergic activation of the hippocampus in mice: A proton magnetic resonance spectroscopy study at 9.4T
    Neurochem. Int. (IF 3.262) Pub Date : 2017-12-21
    Song-I. Lim, Kyu-Ho Song, Chi-Hyeon Yoo, Dong-Cheol Woo, Bo-Young Choe
  • The potential role of the novel hypothalamic neuropeptides nesfatin-1, phoenixin, spexin and kisspeptin in the pathogenesis of anxiety and anorexia nervosa
    Neurochem. Int. (IF 3.262) Pub Date : 2017-12-15
    Artur Pałasz, Małgorzata Janas-Kozik, Amanda Borrow, Oscar Arias-Carrión, John J. Worthington

    Due to the dynamic development of molecular neurobiology and bioinformatic methods several novel brain neuropeptides have been identified and characterized in recent years. Contemporary techniques of selective molecular detection e.g. in situ Real-Time PCR, microdiffusion and some bioinformatics strategies that base on searching for single structural features common to diverse neuropeptides such as hidden Markov model (HMM) have been successfully introduced. A convincing majority of neuropeptides have unique properties as well as a broad spectrum of physiological activity in numerous neuronal pathways including the hypothalamus and limbic system. The newly discovered but uncharacterized regulatory factors nesfatin-1, phoenixin, spexin and kisspeptin have the potential to be unique modulators of stress responses and eating behaviour. Accumulating basic studies revelaed an intriguing role of these neuropeptides in the brain pathways involved in the pathogenesis of anxiety behaviour. Nesfatin-1, phoenixin, spexin and kisspeptin may also distinctly affect the energy homeostasis and modulate food intake not only at the level of hypothalamic centres. Moreover, in patients suffered from anxiety and anorexia nervosa a significant, sex-related changes in the plasma neuropeptide levels occurred. It should be therefore taken into account that the targeted pharmacomodulation of central peptidergic signaling may be potentially helpful in the future treatment of certain neuropsychiatric and metabolic disorders. This article reviews recent evidence dealing with the hypothetical role of these new factors in the anxiety-related circuits and pathophysiology of anorexia nervosa.

  • Neuropathic pain inhibitor, RAP-103, is a potent inhibitor of microglial CCL1/CCR8
    Neurochem. Int. (IF 3.262) Pub Date : 2017-12-14
    Mami Noda, Daichi Tomonaga, Kota Kitazono, Yusaku Yoshioka, Jiadai Liu, Jean-Philippe Rouseau, Richard Kinkead, Michael R. Ruff, Candace B. Pert

    Chemokine signalling is important in neuropathic pain, with microglial cells expressing chemokine (C-C motif) receptor CCR2, CCR5 and CCR8, all playing key roles. In the previous report (Padi et al., 2012), oral administration of a short peptide, RAP-103, for 7 days fully prevents mechanical allodynia and inhibits the development of thermal hyperalgesia after partial ligation of the sciatic nerve in rodents. As for the mechanism of the inhibiting effect of RAP-103, it was speculated to be due to dual blockade of CCR2 and CCR5. We report here that RAP-103 exhibits stronger antagonism for CCR8 (half maximal inhibitory concentration [IC50] 7.7 fM) compared to CCR5 (IC50 < 100 pM) in chemotaxis using primary cultured mouse microglia. In addition, RAP-103 at a concentration of 0.1 pM completely inhibits membrane ruffling and phagocytosis induced by chemokine (C-C motif) ligand 1 (CCL1), an agonist for CCR8. It has been shown that CCL1/CCR8 signaling is important in tactile allodynia induced by nerve ligation. Therefore, CCR8, among other chemokine receptors such as CCR2/CCR5, could be the most potent target for RAP-103. Inhibitory effects of RAP-103 on plural chemokine receptors may play important roles for broad clinical use in neuropathic pain treatment.

  • Sirt3 confers protection against acrolein-induced oxidative stress in cochlear nucleus neurons
    Neurochem. Int. (IF 3.262) Pub Date : 2017-12-14
    Juan Qu, Yong-xiang Wu, Ting Zhang, Yang Qiu, Zhong-jia Ding, Ding-jun Zha

    Acrolein is a ubiquitous dietary and environmental pollutant, which can also be generated endogenously during cellular stress. However, the molecular mechanisms underlying acrolein-induced neurotoxicity, especially in ototoxicity conditions, have not been fully determined. In this study, we investigated the mechanisms on acrolein-induced toxicity in primary cultured cochlear nucleus neurons with focus on Sirt3, a mitochondrial deacetylase. We found that acrolein treatment induced neuronal injury and programmed cell death (PCD) in a dose dependent manner in cochlear nucleus neurons, which was accompanied by increased intracellular reactive oxygen species (ROS) generation and lipid peroxidation. Acrolein exposure also significantly reduced the mitochondrial membrane potential (MMP) levels, promoted cytochrome c release and decreased mitochondrial ATP production. In addition, increased ER tracker fluorescence and activation of ER stress factors were observed after acrolein treatment, and the ER stress inhibitors were shown to attenuate acrolein-induced toxicity in cochlear nucleus neurons. The results of western blot and RT-PCR showed that acrolein markedly decreased the expression of Sirt3 at both mRNA and protein levels, and reduced the activity of downstream mitochondrial enzymes. Furthermore, overexpression of Sirt3 by lentivirus transfection partially prevented acrolein-induced neuronal injury in cochlear nucleus neurons. These results demonstrated that acrolein induces mitochondrial dysfunction and ER stress in cochlear nucleus neurons, and Sirt3 acts as an endogenous protective factor in acrolein-induced ototoxicity.

  • A potential impact of Helicobacter pylori-related galectin-3 in neurodegeneration
    Neurochem. Int. (IF 3.262) Pub Date : 2017-12-13
    Marina Boziki, Stergios A. Polyzos, Georgia Deretzi, Evangelos Kazakos, Panagiotis Katsinelos, Michael Doulberis, Georgios Kotronis, Evaggelia Giartza-Taxidou, Leonidas Laskaridis, Dimitri Tzivras, Elisabeth Vardaka, Constantinos Kountouras, Nikolaos Grigoriadis, Thomann Robert, Jannis Kountouras
  • Trophic modulation of gamma oscillations: The key role of processing protease for Neuregulin-1 and BDNF precursors
    Neurochem. Int. (IF 3.262) Pub Date : 2017-12-09
    Hideki Tamura, Sadao Shiosaka, Shota Morikawa

    Gamma oscillations within the cerebral cortex and hippocampus are associated with cognitive processes, including attention, sensory perception, and memory formation; a deficit in gamma regulation is a common symptom of neurologic and psychiatric disorders. Accumulating evidence has suggested that gamma oscillations result from the synchronized activity of cell assemblies coordinated mainly by parvalbumin-positive inhibitory interneurons. The modulator molecules for parvalbumin-positive interneurons are major research targets and have the potential to control the specific oscillatory rhythm and behavior originating from neural coordination. Neuregulin-1 and brain-derived neurotrophic factor have been focused on as synaptic trophic factors that are associated with gamma oscillations. Synaptic activity converts precursor trophic factors into their biologically active forms by proteolytic cleavage, which could, in turn, modulate cell excitability and synaptic plasticity through each receptor's signaling. From these findings, the processing of trophic factors by proteases in a synaptic microenvironment might involve gamma oscillations during cognition. Here, we review the trophic modulation of gamma oscillations through extracellular proteolysis and its implications in neuronal diseases.

  • Strong sonic hedgehog signaling in the mouse ventral spinal cord is not required for oligodendrocyte precursor cell (OPC) generation but is necessary for correct timing of its generation
    Neurochem. Int. (IF 3.262) Pub Date : 2017-11-06
    Hirokazu Hashimoto, Wen Jiang, Takeshi Yoshimura, Kyeong-Hye Moon, Jinwoong Bok, Kazuhiro Ikenaka

    In the mouse neural tube, sonic hedgehog (Shh) secreted from the floor plate (FP) and the notochord (NC) regulates ventral patterning of the neural tube, and later is essential for the generation of oligodendrocyte precursor cells (OPCs). During early development, the NC is adjacent to the neural tube and induces ventral domains in it, including the FP. In the later stage of development, during gliogenesis in the spinal cord, the pMN domain receives strong Shh signaling input. While this is considered to be essential for the generation of OPCs, the actual role of this strong input in OPC generation remains unclear. Here we studied OPC generation in bromi mutant mice which show abnormal ciliary structure. Shh signaling occurs within cilia and has been reported to be weak in bromi mutants. At E11.5, accumulation of Patched1 mRNA, a Shh signaling reporter, is observed in the pMN domain of wild type but not bromi mutants, whereas expression of Gli1 mRNA, another Shh reporter, disappeared. Thus, Shh signaling input to the pMN domain at E12.5 was reduced in bromi mutant mice. In these mutants, induction of the FP structure was delayed and its size was reduced compared to wild type mice. Furthermore, while the p3 and pMN domains were induced, the length of the Nkx2.2-positive region and the number of Olig2-positive cells decreased. The number of OPCs was also significantly decreased in the E12.5 and E14.5 bromi mutant spinal cord. In contrast, motor neuron (MN) production, detected by HB9 expression, significantly increased. It is likely that the transition from MN production to OPC generation in the pMN domain is impaired in bromi mutant mice. These results suggest that strong Shh input to the pMN domain is not required for OPC generation but is essential for producing a sufficient number of OPCs.

  • Insulin expression in cultured astrocytes and the decrease by amyloid β
    Neurochem. Int. (IF 3.262) Pub Date : 2017-11-03
    Katsura Takano, Keisuke Koarashi, Kenji Kawabe, Masanori Itakura, Hidemitsu Nakajima, Mitsuaki Moriyama, Yoichi Nakamura

    Insulin resistance in brain has been reported in Alzheimer's diseases (AD). Insulin signaling is important for homeostasis in brain function and reported to be disturbed in neurons leading to tau phosphorylation and neurofibrillary tangles. Many investigations of insulin in neurons have been reported; however, it has not been reported whether astrocytes also produce insulin. In the present study, we assessed the expression of insulin in astrocytes cultured from rat embryonic brain and the effects of amyloid β1-42 (Aβ) and lipopolysaccharide (LPS) on the expression. We found that astrocytes expressed preproinsulin mRNAs and insulin protein, and that Aβ or LPS decreased these expressions. Antioxidants, glutathione and N-acetylcysteine, restored the decreases in insulin mRNA expression by Aβ and by LPS. Insulin protein was detected in astrocyte conditioned medium. These results suggest that astrocytes express and secrete insulin. Oxidative stress might be involved in the decreased insulin expression by Aβ or LPS. The insulin decrease by Aβ in astrocytes could be a novel disturbing mechanism for brain insulin signaling in AD.

  • Icariside II, a PDE5 inhibitor from Epimedium brevicornum, promotes neuron-like pheochromocytoma PC12 cell proliferation via activating NO/cGMP/PKG pathway
    Neurochem. Int. (IF 3.262) Pub Date : 2017-10-31
    Jianmei Gao, Yingshu Xu, Ming Lei, Jingshan Shi, Qihai Gong

    Icariside II (ICS II), a phosphodiesterase 5 inhibitor (PDE 5-I), is a major ingredient of Epimedium brevicornum, with wide spectrum of neuroprotective properties. However, little is known about the potential beneficial effect of ICS II on neuronal cell proliferation, and its possible underlying mechanism remains still unclear. We hypothesized that the beneficial effect of ICS II on neuron-like highly differentiated rat pheochromocytoma (PC12) cell proliferation is correlated with the nitric oxide (NO) signaling pathway and its upstream of PI3K/AKT pathway. PC12 cells were treated with ICS II alone or together with L-NMMA, H89, KT-5823, and/or LY294002 (the inhibitor of NOS, PKA, PKG, PI3K, respectively). It was found that ICS II concentration-dependently promoted PC12 cells proliferation, and cell cycle analysis showed that the proportion of ICS II-treated PC12 cells in S phase was higher than that of control. Moreover, ICS II at the appropriate concentration (100 μM) not only increased nNOS expression, NO production, but also enhanced cGMP content and PKG activity. The addition of L-NMMA and KT-5 823 significantly inhibited the effects of ICS II on nNOS expression, NO production and PKG activity. Furthermore, LY294002 significantly decreased p-AKT level, NOS activity, NO production and nNOS expression, but it did not affect iNOS expression. These findings demonstrate that the beneficial effect of ICS II on neuronal cell proliferation, and its possible underlying mechanisms are, at least partly, through activating AKT/nNOS/NO/cGMP/PKG signaling pathway.

  • Motoneuron degeneration in the trigeminal motor nucleus innervating the masseter muscle in Dystonia musculorum mice
    Neurochem. Int. (IF 3.262) Pub Date : 2017-10-21
    M. Ibrahim Hossain, Masao Horie, Nozomu Yoshioka, Masayuki Kurose, Kensuke Yamamura, Hirohide Takebayashi

    Dystonia musculorum (dt) mice, which have a mutation in the Dystonin (Dst) gene, are used as animal models to investigate the human disease known as hereditary sensory and autonomic neuropathy type VI. Massive neuronal cell death is observed, mainly in the peripheral nervous system (PNS) of dt mice. We and others have recently reported a histopathological feature of these mice that neurofilament (NF) accumulates in various areas of the central nervous system (CNS), including motor pathways. Although dt mice show motor disorder and growth retardation, the causes for these are still unknown. Here we performed histopathological analyses on motor units of the trigeminal motor nucleus (Mo5 nucleus), because they are a good system to understand neuronal responses in the mutant CNS, and abnormalities in this system may lead to problems in mastication, with subsequent growth retardation. We report that motoneurons with NF accumulation in the Mo5 nuclei of DstGt homozygous mice express the stress-induced genes CHOP, ATF3, and lipocalin 2 (Lcn2). We also show a reduced number of Mo5 motoneurons and a reduced size of Mo5 nuclei in DstGt homozygous mice, possibly due to apoptosis, given the presence of cleaved caspase 3-positive Mo5 motoneurons. In the mandibular (V3) branches of the trigeminal nerve, which contains axons of Mo5 motoneurons and trigeminal sensory neurons, there was infiltration of Iba1-positive macrophages. Finally, we report atrophy of the masseter muscles in DstGt homozygous mice, which showed abnormal nuclear localization of myofibrils and increased expression of atrogin-1 mRNA, a muscle atrophy-related gene and weaker masseter muscle strength with uncontrolled muscle activity by electromyography (EMG). Taken together, our findings strongly suggest that mastication in dt mice is affected due to abnormalities of Mo5 motoneurons and masseter muscles, leading to growth retardation at the post-weaning stages.

  • Release of soluble and vesicular purine nucleoside phosphorylase from rat astrocytes and microglia induced by pro-inflammatory stimulation with extracellular ATP via P2X7 receptors
    Neurochem. Int. (IF 3.262) Pub Date : 2017-10-20
    Luis Emiliano Peña-Altamira, Elisabetta Polazzi, Patricia Giuliani, Alina Beraudi, Francesca Massenzio, Ilaria Mengoni, Alessandro Poli, Mariachiara Zuccarini, Renata Ciccarelli, Patrizia Di Iorio, Marco Virgili, Barbara Monti, Francesco Caciagli

    Purine nucleoside phosphorylase (PNP), a crucial enzyme in purine metabolism which converts ribonucleosides into purine bases, has mainly been found inside glial cells. Since we recently demonstrated that PNP is released from rat C6 glioma cells, we then wondered whether this occurs in normal brain cells. Using rat primary cultures of microglia, astrocytes and cerebellar granule neurons, we found that in basal condition all these cells constitutively released a metabolically active PNP with Km values very similar to those measured in C6 glioma cells. However, the enzyme expression/release was greater in microglia or astrocytes that in neurons. Moreover, we exposed primary brain cell cultures to pro-inflammatory agents such as lipopolysaccharide (LPS) or ATP alone or in combination. LPS alone caused an increased interleukin-1β (IL-1β) secretion mainly from microglia and no modification in the PNP release, even from neurons in which it enhanced cell death. In contrast, ATP administered alone to glial cells at high micromolar concentrations significantly stimulated the release of PNP within 1 h, an effect not modified by LPS presence, whereas IL-1β secretion was stimulated by ATP only in cells primed for 2 h with LPS. In both cases ATP effect was mediated by P2X7 receptor (P2X7R), since it was mimicked by cell exposure to Bz-ATP, an agonist of P2X7R, and blocked by cell pre-treatment with the P2X7R antagonist A438079. Interestingly, ATP-induced PNP release from glial cells partly occurred through the secretion of lysosomal vesicles in the extracellular medium. Thus, during inflammatory cerebral events PNP secretion promoted by extracellular ATP accumulation might concur to control extracellular purine signals. Further studies could elucidate whether, in these conditions, a consensual activity of enzymes downstream of PNP in the purine metabolic cascade avoids accumulation of extracellular purine bases that might concur to brain injury by unusual formation of reactive oxygen species.

  • Calcium uptake and cytochrome c release from normal and ischemic brain mitochondria
    Neurochem. Int. (IF 3.262) Pub Date : 2017-10-16
    Alexander Andreyev, Pratistha Tamrakar, Robert E. Rosenthal, Gary Fiskum

    At abnormally elevated levels of intracellular Ca2+, mitochondrial Ca2+ uptake may compromise mitochondrial electron transport activities and trigger membrane permeability changes that allow for release of cytochrome c and other mitochondrial apoptotic proteins into the cytosol. In this study, a clinically relevant canine cardiac arrest model was used to assess the effects of global cerebral ischemia and reperfusion on mitochondrial Ca2+ uptake capacity, Ca2+ uptake-mediated inhibition of respiration, and Ca2+-induced cytochrome c release, as measured in vitro in a K+-based medium in the presence of Mg2+, ATP, and NADH-linked oxidizable substrates. Maximum Ca2+ uptake by frontal cortex mitochondria was significantly lower following 10 min cardiac arrest compared to non-ischemic controls. Mitochondria from ischemic brains were also more sensitive to the respiratory inhibition associated with accumulation of large levels of Ca2+. Cytochrome c was released from brain mitochondria in vitro in a Ca2+-dose-dependent manner and was more pronounced following both 10 min of ischemia alone and following 24 h reperfusion, in comparison to mitochondria from non-ischemic Shams. These effects of ischemia and reperfusion on brain mitochondria could compromise intracellular Ca2+ homeostasis, decrease aerobic and increase anaerobic cerebral energy metabolism, and potentiate the cytochrome c-dependent induction of apoptosis, when re-oxygenated mitochondria are exposed to abnormally high levels of intracellular Ca2+.

  • 3-Iodothyroacetic acid (TA1), a by-product of thyroid hormone metabolism, reduces the hypnotic effect of ethanol without interacting at GABA-A receptors
    Neurochem. Int. (IF 3.262) Pub Date : 2017-10-12
    Annunziatina Laurino, Elisa Landucci, Francesco Resta, Gaetano De Siena, Rosanna Matucci, Alessio Masi, Laura Raimondi

    3-iodothyroacetic acid (TA1) is among the by-products of thyroid hormone metabolism suspected to mediate the non-genomic effects of the hormone (T3). We aim to investigate whether TA1 systemically administered to mice stimulated mice wakefulness, an effect already described for T3 and for another T3 metabolite (i.e. 3-iodothryonamine; T1AM), and whether TA1 interacted at GABA-A receptors (GABA-AR). Mice were pre-treated with either saline (vehicle) or TA1 (1.32, 4 and 11 μg/kg) and, after 10 min, they received ethanol (3.5 g/kg, i.p.). In another set of experiments, TA1 was administered 5 min after ethanol. The latency of sleep onset and the time of sleep duration were recorded. Voltage-clamp experiments to evaluate the effect of 1 μM TA1 on bicuculline-sensitive currents in acute rat hippocampal slice neurons and binding experiments evaluating the capacity of 1, 10, 100 μM TA1 to displace [3H]flumazenil from mice brain membranes were also performed. 4 μg/kg TA1 increases the latency of onset and at 1.32 and 4 μg/kg it reduces the duration of ethanol-induced sleep only if administered before ethanol. TA1 does not functionally interact at GABA-AR. Overall these results indicate a further similarity between the pharmacological profile of TA1 and that of T1AM.

  • Sitagliptin enhances the neuroprotective effect of pregabalin against pentylenetetrazole-induced acute epileptogenesis in mice: Implication of oxidative, inflammatory, apoptotic and autophagy pathways
    Neurochem. Int. (IF 3.262) Pub Date : 2017-10-12
    Manar A. Nader, Hayam Ateyya, Mohamed El-Shafey, Nagla A. El-Sherbeeny

    The current investigation aimed at studying the anti-epileptogenic effect of sitagliptin. The possible effect of the drug in combination with pregabalin in pentylenetetrazole (PTZ)- induced seizures was studied. In addition, the postulated mechanisms that could mediate such effect were explored namely, suppression of oxidative stress and neuro-inflammatory markers, autophagy and apoptosis. Seven days prior to PTZ (60 mg/kg, sc) injection, mice were treated with sitagliptin (5, 15, and 60 mg/kg, twice daily, orally) or pregabalin (30 mg/kg, once daily, orally) or their combination. At the end of the experiment, several parameters were assessed including: oxidative/nitro-oxidative stress such as superoxide dismutase (SOD), reduced glutathione (GSH), glutathione peroxidase (GP-x) catalase (CAT), and lipid peroxidation assessed as malondialdehyde (MDA), nitrate/nitrite (NOx), 3-nitrotyrosine (3-NT). Seizure latency was evaluated. Neuronal damage was also assessed by performing tissue staining by hematoxylin and eosin, estimating hippocampus level of glutamate, gamma-aminobutyric acid (GABA), glial fibrillary acidic protein (GFAP) and brain-derived neurotrophic factor (BDNF). Also, markers for inflammation, autophagy and apoptosis were measured, nuclear factor erythroid-derived 2- like 2 (Nrf2), nuclear factor kappa-B (NF-κB), phosphatidylethanolamine-conjugated form of microtubule-associated protein light chain-3 (LC3-II), casapase-3, Bcl-2-like protein 4 (BAX) and glucagon like peptide-1 (GLP-1) activity. Sitagliptin significantly suppressed epileptogenesis in PTZ-induced seizures. Sitagliptin counteracted neuronal damage and all biochemical, and histo-chemical alteration induced by PTZ. Also, a more significant protective effect was observed after combination with pregabalin. This study is indicative for the antiepileptogenic potential of sitagliptin with or without pregabalin in the PTZ model of epilepsy which is likely to be through its effect on antioxidant, anti-apoptotic and autophagic pathways.

  • Dual effects of insect nAChR chaperone RIC-3 on hybrid receptor: Promoting assembly on endoplasmic reticulum but suppressing transport to plasma membrane on Xenopus oocytes
    Neurochem. Int. (IF 3.262) Pub Date : 2017-10-12
    Haibo Bao, Xixia Xu, Wei Liu, Na Yu, Zewen Liu

    Resistance to inhibitors of cholinesterase (RIC) −3 promotes the maturation (folding and assembly) of neuronal nicotinic acetylcholine receptors (nAChRs) as a molecular chaperone. The modulation effects of RIC-3 on homomeric α7 nAChRs are always positive, but its effects on heteromeric subtypes are inconsistent among reports. In this study, five RIC-3 isoforms were identified from Locusta migratoria. Four isoforms showed obvious effects on hybrid receptor Locα1/rβ2 expressed in Xenopus oocytes. As a representative, the co-expression of RIC-3v4 exhibited the decreased agonist responses (Imax) on oocytes, lower specific [3H]epibatidine binding (Bmax) on plasma membrane protein (PMP), and reduced subunit levels in PMP, which showed that the mature Locα1/rβ2 on the plasma membrane was decreased by the co-expression of RIC-3. In contrast, the [3H]epibatidine binding and mature Locα1/rβ2 levels in the endoplasmic reticulum membrane protein (ERMP) were much increased when co-expressing with RIC-3v4. The [3H]epibatidine binding and mature Locα1/rβ2 levels in total membrane protein (TMP) gave the similar results as that in ERMP. Taking data together, the results showed that the co-expression of RIC-3 increased the mature Locα1/rβ2 receptor levels on ER of Xenopus oocytes, but these mature receptors were mostly kept on ER and suppressed to transport to plasma membrane.

  • Quantitative temporal changes in DTI values coupled with histological properties in cuprizone-induced demyelination and remyelination
    Neurochem. Int. (IF 3.262) Pub Date : 2017-10-10
    Ryutaro Yano, Junichi Hata, Yoshifumi Abe, Fumiko Seki, Keitaro Yoshida, Yuji Komaki, Hideyuki Okano, Kenji F. Tanaka

    Diffusion tensor imaging (DTI) is widely used to evaluate microstructural variations in brain tissue. In particular, fractional anisotropy (FA), reflecting the magnitude and orientation of anisotropic water diffusion, allows us to detect pathological events in white matter. An ex vivo DTI study coupled with histological assessment is an efficient strategy to evaluate the myelination process, i.e. demyelination and remyelination. The relationship between DTI values and myelin content or the individual cellular components such as oligodendrocytes, microglia, and astrocytes during both processes of demyelination and remyelination are not well-understood. To address this issue, we employed a cuprizone-inducible demyelination mouse model. Demyelination can be induced in this model during cuprizone exposure and termination of cuprizone exposure induces remyelination. We fed the mice cuprizone-containing chow for 4 weeks and then normal chow for an additional 4 weeks. The ex vivo DTI was performed to evaluate the white matter profiles observed by FA, mean diffusivity (MD), and radial diffusivity (RD) at both demyelinating and remyelinating time points, and then we evaluated histological properties at the same time points. The results indicated a gradual FA decrease during the cuprizone treatment (0, 2, 3, 4 weeks). A lower peak was seen at 1 week after the normal chow was resumed, with recovery to baseline at 2 and 4 weeks. MD and RD showed an opposing pattern to that of FA. These DTI values were positively or negatively correlated with myelin content regardless of the status of the white matter. The RD value was more sensitive to myelination status than FA and MD. We have clarified the temporal changes in the DTI values coupled with histological properties over both the demyelination and remyelination processes.

  • Resveratrol activation of AMPK-dependent pathways is neuroprotective in human neural stem cells against amyloid-beta-induced inflammation and oxidative stress
    Neurochem. Int. (IF 3.262) Pub Date : 2017-10-05
    Ming-Chang Chiang, Christopher J. Nicol, Yi-Chuan Cheng

    Alzheimer's disease (AD) is a neurodegenerative disorder with progressive memory loss resulting in dementia. Amyloid-beta (Aβ) peptides play a critical role in the pathogenesis of this disease, and are thought to promote inflammation and oxidative stress leading to neurodegeneration in the neocortex and hippocampus of the AD brains. AMP-activated protein kinase (AMPK) is a master regulator of cellular energy homeostasis, and cell survival in response to inflammation and oxidative stress. However, the neuroprotective mechanisms by which AMPK achieves these beneficial effects in human neural stem cells (hNSCs) exposed to Aβ is still not well understood. Resveratrol is a potent activator of AMPK suggesting it may have therapeutic potential against AD. Therefore, we will test the hypothesis that the AMPK activator resveratrol protects against Aβ mediated neuronal impairment (inflammation and oxidative stress) in hNSCs. Here, Aβ-treated hNSCs had significantly decreased cell viability that correlated with increased TNF-α and IL-1β inflammatory cytokine expression. Co-treatment with resveratrol significantly abrogated the Aβ-mediated effects in hNSCs, and was effectively blocked by the addition of the AMPK-specific antagonist (Compound C). These results suggest the neuroprotective effects of resveratrol are mediated by an AMPK-dependent pathway. In addition, resveratrol rescued the transcript expression levels of inhibitory kappa B kinase (IKK) in Aβ-treated hNSCs. NF-κB is a transcription factor with a key role in the expression of a variety of genes involved in inflammatory responses. Resveratrol prevented the Aβ-mediated increases in NF-κB mRNA and protein levels, and its nuclear translocation in hNSCs. Co-treatment with resveratrol also significantly restored iNOS and COX-2 levels in Aβ-treated hNSCs. Furthermore, hNSCs co-treated with resveratrol were significantly rescued from Aβ-induced oxidative stress, which correlated with reversal of the Aβ-induced mRNA decrease in oxidative defense genes (SOD-1, NRF2, Gpx1, Catalase, GSH and HO-1). Taken together, these novel findings show that activation of AMPK-dependent signaling by resveratrol rescues Aβ-mediated neurotoxicity in hNSCs, and provides evidence supporting a neuroprotective role for AMPK activating drugs in Aβ-related diseases such as AD.

  • Roles of CSGalNAcT1, a key enzyme in regulation of CS synthesis, in neuronal regeneration and plasticity
    Neurochem. Int. (IF 3.262) Pub Date : 2017-10-05
    Michihiro Igarashi, Kosei Takeuchi, Sayaka Sugiyama

    Chondroitin sulfate (CS) is a sulfated glycosaminoglycan composed of a long chain of repeating disaccharide units that are attached to core proteins, resulting in CS proteoglycans (CSPGs). In the mature brain, CS is concentrated in perineuronal nets (PNNs), which are extracellular structures that surround synapses and regulate synaptic plasticity. In addition, CS is rapidly synthesized after CNS injury to create a physical and chemical barrier that inhibits axon growth. Most previous studies used a bacterial CS-degrading enzyme to investigate the physiological roles of CS. Recent studies have shown that CS is synthesized by more than 15 enzymes, all of which have been characterized in vitro. Here we focus on one of those enzymes, CSGalNAcT1 (T1). We produced T1 knockout mice (KO), which show extensive axon regeneration following spinal cord injury, as well as the loss of onset of ocular dominance plasticity. These results from T1KO mice suggest important roles for extracellular CS in the brain regarding neuronal plasticity and axon regeneration.

  • Involvement of neuronal and glial activities in control of the extracellular d-serine concentrations by the AMPA glutamate receptor in the mouse medial prefrontal cortex
    Neurochem. Int. (IF 3.262) Pub Date : 2017-09-28
    Sayuri Ishiwata, Asami Umino, Toru Nishikawa

    It has been well accepted that d-serine may be an exclusive endogenous coagonist for the N-methyl-d-aspartate (NMDA)-type glutamate receptor in mammalian forebrain regions. We have recently found by using an in vivo dialysis method that an intra-medial prefrontal cortex infusion of S-α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (S-AMPA), a selective AMPA-type glutamate receptor agonist, causes a reduction in the extracellular levels of d-serine in a calcium-permeable AMPA receptor antagonist-sensitive manner. The inhibitory influence by the AMPA receptor on the extracellular d-serine, however, contradicts the data obtained from in vitro experiments that the AMPA receptor stimulation leads to facilitation of the d-serine liberation. This discrepancy appears to be due to the different cell setups between the in vivo and in vitro preparations. From the viewpoints of the previous reports indicating (1) the neuronal presence of d-serine synthesizing enzyme, serine racemase, and d-serine-like immunoreactivity and (2) the same high tissue concentrations of d-serine in the glia-enriched white matter and in the neuron-enriched gray matter of the mammalian neocortex, we have now investigated in the mouse medial prefrontal cortex, the effects of attenuation of neuronal and glial activities, by tetrodotoxin or fluorocitrate, respectively, on the S-AMPA-induced downregulation of the extracellular d-serine contents. In vivo dialysis studies revealed that a local infusion of tetrodotoxin or fluorocitrate eliminated the ability of S-AMPA given intra-cortically to cause a significant decrease in the dialysate concentrations of d-serine without affecting the elevating effects of S-AMPA on those of glycine, another intrinsic coagonist for the NMDA receptor. These findings suggest that the control by the AMPA receptor of the extracellular d-serine levels could be modulated by the neuronal and glial activities in the prefrontal cortex. It cannot be excluded that fluorocitrate would indirectly alter the modulation by changing synaptic neurotransmission via glial activity attenuation as previously reported.

  • Vesicular movements in the growth cone
    Neurochem. Int. (IF 3.262) Pub Date : 2017-09-27
    Motohiro Nozumi, Michihiro Igarashi

    Growth cones, which are the highly motile tips of extending neuronal processes in developing neurons, have many vesicles. These vesicles are likely essential for the membrane expansion that is required for nerve growth, and probably coordinate with rearrangement of the cytoskeletons. Such mechanisms are poorly understood from molecular and cell biological aspects. Recently, we used superresolution microscopic approaches and described new mechanisms that are involved in the interaction between the vesicles and F-actin in the leading edge of the peripheral domain. Vesicles mainly accumulate in the central domain of growth cones. However, the dynamics of vesicles in each domain, for example, clathrin dependency, are totally distinct from each other. Here, we discuss the diversity of the dynamics of vesicular and related proteins that play different roles in nerve growth.

  • Sex differences in the mitochondrial bioenergetics of astrocytes but not microglia at a physiologically relevant brain oxygen tension
    Neurochem. Int. (IF 3.262) Pub Date : 2017-09-06
    Sausan M. Jaber, Evan A. Bordt, Niraj M. Bhatt, Daniel M. Lewis, Sharon Gerecht, Gary Fiskum, Brian M. Polster

    Biological sex is thought to influence mitochondrial bioenergetic function. Previous respiration measurements examining brain mitochondrial sex differences were made at atmospheric oxygen using isolated brain mitochondria. Oxygen is 160 mm Hg (21%) in the atmosphere, while the oxygen tension in the brain generally ranges from ∼5 to 45 mm Hg (∼1–6% O2). This study tested the hypothesis that sex and/or brain physiological oxygen tension influence the mitochondrial bioenergetic properties of primary rat cortical astrocytes and microglia. Oxygen consumption was measured with a Seahorse XF24 cell respirometer in an oxygen-controlled environmental chamber. Strikingly, male astrocytes had a higher maximal respiration than female astrocytes when cultured and assayed at 3% O2. Three percent O2 yielded a low physiological dissolved O2 level of ∼1.2% (9.1 mm Hg) at the cell monolayer during culture and 1.2–3.0% O2 during assays. No differences in bioenergetic parameters were observed between male and female astrocytes at 21% O2 (dissolved O2 of ∼19.7%, 150 mm Hg during culture) or between either of these cell populations and female astrocytes at 3% O2. In contrast to astrocytes, microglia showed no sex differences in mitochondrial bioenergetic parameters at either oxygen level, regardless of whether they were non-stimulated or activated to a proinflammatory state. There were also no O2- or sex-dependent differences in proinflammatory TNF-α or IL-1β cytokine secretion measured at 18 h activation. Overall, results reveal an intriguing sex variance in astrocytic maximal respiration that requires additional investigation. Findings also demonstrate that sex differences can be masked by conducting experiments at non-physiological O2.

  • Alterations in the E3 ligases Parkin and CHIP result in unique metabolic signaling defects and mitochondrial quality control issues
    Neurochem. Int. (IF 3.262) Pub Date : 2017-08-26
    Britney N. Lizama, Amy M. Palubinsky, BethAnn McLaughlin

    E3 ligases are essential scaffold proteins, facilitating the transfer of ubiquitin from E2 enzymes to lysine residues of client proteins via isopeptide bonds. The specificity of substrate binding and the expression and localization of E3 ligases can, however, endow these proteins with unique features with variable effects on mitochondrial, metabolic and CNS function. By comparing and contrasting two E3 ligases, Parkin and C-terminus of HSC70-Interacting protein (CHIP) we seek to highlight the biophysical properties that may promote mitochondrial dysfunction, acute stress signaling and critical developmental periods to cease in response to mutations in these genes. Encoded by over 600 human genes, RING-finger proteins are the largest class of E3 ligases. Parkin contains three RING finger domains, with R1 and R2 separated by an in-between region (IBR) domain. Loss-of-function mutations in Parkin were identified in patients with early onset Parkinson's disease. CHIP is a member of the Ubox family of E3 ligases. It contains an N-terminal TPR domain and forms unique asymmetric homodimers. While CHIP can substitute for mutated Parkin and enhance survival, CHIP also has unique functions. The differences between these proteins are underscored by the observation that unlike Parkin-deficient animals, CHIP-null animals age prematurely and have significantly impaired motor function. These properties make these E3 ligases appealing targets for clinical intervention. In this work, we discuss how biophysical and metabolic properties of these E3 ligases have driven rapid progress in identifying roles for E3 ligases in development, proteostasis, mitochondrial biology, and cell health, as well as new data about how these proteins alter the CNS proteome.

  • Analysis of lipid raft molecules in the living brain slices
    Neurochem. Int. (IF 3.262) Pub Date : 2017-08-24
    Norihiro Kotani, Takanari Nakano, Yui Ida, Rina Ito, Miki Hashizume, Arisa Yamaguchi, Makoto Seo, Tomoyuki Araki, Yasushi Hojo, Koichi Honke, Takayuki Murakoshi

    Neuronal plasma membrane has been thought to retain a lot of lipid raft components which play important roles in the neural function. Although the biochemical analyses of lipid raft using brain tissues have been extensively carried out in the past 20 years, many of their experimental conditions do not coincide with those of standard neuroscience researches such as neurophysiology and neuropharmacology. Hence, the physiological methods for lipid raft analysis that can be compatible with general neuroscience have been required. Herein, we developed a system to physiologically analyze ganglioside GM1-enriched lipid rafts in brain tissues using the “Enzyme-Mediated Activation of Radical Sources (EMARS)” method that we reported (Kotani N. et al. Proc. Natl. Acad. Sci. U S A 105, 7405–7409 (2008)). The EMARS method was applied to acute brain slices prepared from mouse brains in aCSF solution using the EMARS probe, HRP-conjugated cholera toxin subunit B, which recognizes ganglioside GM1. The membrane molecules present in the GM1-enriched lipid rafts were then labeled with fluorescein under the physiological condition. The fluorescein-tagged lipid raft molecules called “EMARS products” distributed differentially among various parts of the brain. On the other hand, appreciable differences were not detected among segments along the longitudinal axis of the hippocampus. We further developed a device to label the lipid raft molecules in acute hippocampal slices under two different physiological conditions to detect dynamics of the lipid raft molecules during neural excitation. Using this device, several cell membrane molecules including Thy1, known as a lipid raft resident molecule in neurons, were confirmed by the EMARS method in living hippocampal slices.

  • P2Y12 shRNA treatment relieved HIV gp120-induced neuropathic pain in rats
    Neurochem. Int. (IF 3.262) Pub Date : 2017-08-18
    Liran Shi, Bing Wu, Zhihua Yi, Shanhong Zhao, Lifang Zou, Lin Li, Huilong Yuan, Tianyu Jia, Shuangmei Liu, Hui Liu, Yun Gao, Guilin Li, Hong Xu, Chunping Zhang, Shangdong Liang

    Human immunodeficiency virus (HIV) envelope glycoprotein (glycoprotein 120, gp120) can induce chronic neuropathic pain by directly stimulating primary sensory afferent neurons. Activation of satellite glial cells (SGCs) in dorsal root ganglia (DRG) plays an important role in the transmission of neuropathic pain. The P2Y12 receptor is expressed in SGCs of DRG. In this study, we investigated the role of the P2Y12 receptor in HIV gp120-induced neuropathic pain. The results showed that peripheral nerve exposure to HIV gp120 increased mechanical and thermal hyperalgesia in gp120-treated model rats. The gp120 treatment increased the expression of P2Y12 mRNA and protein in DRG SGCs. Treatment with P2Y12 short hairpin RNA (shRNA) in DRG SGCs decreased the upregulated expression of P2Y12 mRNA and protein in DRG SGCs as well as relieved mechanical and thermal hyperalgesia in gp120-treated rats. Reduction of P2Y12 receptor decreased co-expression of P2Y12 and glial fibrillary acidic protein (GFAP), expression of GFAP, interleukin (IL)-1β, tumor necrosis factor (TNF)-receptor 1 (TNF-R1), and phosphorylation of Akt (p-Akt) proteins in DRG of gp120-treated rats. Upregulation of GFAP is a marker of SGC activation. Therefore, P2Y12 shRNA treatment decreased HIV gp120-induced mechanical and thermal hyperalgesia in gp120-treated rats.

  • Alzheimer's disease as oligomeropathy
    Neurochem. Int. (IF 3.262) Pub Date : 2017-08-16
    Kenjiro Ono

    Alzheimer's disease (AD) is the most common age-related neurodegenerative disorder and is characterized by pathological aggregates of amyloid β-protein (Aβ) and tau protein. On the basis of genetic evidence, biochemical data, and animal models, Aβ has been suggested to be responsible for the pathogenesis of AD (the amyloid hypothesis). Aβ molecules tend to aggregate to form oligomers, protofibrils, and mature fibrils. Although mature fibrils in the final stage have been thought to be the cause of AD pathogenesis, recent studies using synthetic Aβ peptides, a cell culture model, Aβ precursor protein transgenic mice models, and human samples, such as cerebrospinal fluids and postmortem brains of AD patients, suggest that pre-fibrillar forms (oligomers of Aβ) are more deleterious than are extracellular fibril forms. Based on this recent evidence showing that oligomers have a central role in the pathogenesis of AD, the term “oligomeropathy” could be used to define AD and other protein-misfolding diseases. In this review, I discuss recent developments in the “oligomer hypothesis” including our research findings regarding the pathogenesis of AD.

  • 4-Hydroperoxy-2-decenoic acid ethyl ester protects against 6-hydroxydopamine-induced cell death via activation of Nrf2-ARE and eIF2α-ATF4 pathways
    Neurochem. Int. (IF 3.262) Pub Date : 2017-08-16
    Yuki Inoue, Hirokazu Hara, Yukari Mitsugi, Eiji Yamaguchi, Tetsuro Kamiya, Akichika Itoh, Tetsuo Adachi

    Parkinson's disease (PD) is a neurodegenerative disorder characterized by progressive degeneration of dopaminergic neurons in the substantia nigra. Oxidative stress has been reported to be closely related to the pathogenesis and worsening of symptoms of PD. One therapeutic strategy is to alleviate neuronal injuries caused by oxidative stress. In this study, we investigated protective effects of royal jelly (RJ) fatty acids and their derivatives on oxidative stress-induced cell death using human neuroblastoma SH-SY5Y cells. 4-Hydroperoxy-2-decenoic acid ethyl ester (HPO-DAEE), a synthesized RJ fatty acid derivative, markedly induced antioxidant enzymes such as heme oxygenase-1 (HO-1). Pretreatment with HPO-DAEE protected against 6-hydroxydopamine (6-OHDA)-induced cell death. NF-E2-related factor 2 (Nrf2), a master regulator of antioxidative responses, plays a key role in the acquisition of resistance to oxidative stress. HPO-DAEE elicited nuclear accumulation of Nrf2 and activated antioxidant response element (ARE), a cis-activating regulatory element, indicating that HPO-DAEE induced expression of antioxidant genes through Nrf2-ARE signaling. Recently, the activating transcription factor-4 (ATF4) has been shown to cooperate with Nrf2 and modulate antioxidant gene expression. We also found that HPO-DAEE promoted phosphorylation of eukaryotic initiation factor 2α (eIF2α), which is an upstream effector of ATF4, and subsequent nuclear accumulation of ATF4. The eIF2α phosphatase inhibitor, salubrinal, augmented HPO-DAEE-induced HO-1 expression and protection against 6-OHDA-induced cell death. These results indicate that HPO-DAEE activates both the Nrf2-ARE and eIF2α-ATF4 pathways. Moreover, ROS generation occurred upon treatment of SH-SY5Y cells with HPO-DAEE, and the antioxidants N-acetylcysteine and glutathione suppressed HPO-DAEE-induced activation of the Nrf2-ARE and eIF2α-ATF4 pathways. Therefore, sublethal oxidative stress caused by HPO-DAEE is likely to activate both these pathways. Taken together, we conclude that HPO-DAEE elicits adaptive responses to oxidative stress through cooperative activation of the Nrf2-ARE and eIF2α-ATF4 pathways.

  • 1,25-Dihydroxyvitamin-D3 induces brain proteomic changes in cuprizone mice during remyelination involving calcium proteins
    Neurochem. Int. (IF 3.262) Pub Date : 2017-08-14
    Eystein Oveland, Agnes Nystad, Frode Berven, Kjell-Morten Myhr, Øivind Torkildsen, Stig Wergeland

    Dietary supplementation of vitamin D is commonly recommended to patients with multiple sclerosis. We recently found that high-dose of the hormonally active 1,25-dihydroxyvitamin-D3 (1,25D) promotes myelin repair in the cuprizone model for de- and remyelination. In the present study, we quantified 5062 proteins, of which 125 were differentially regulated in brain tissue from 1,25D treated mice during remyelination, compared to placebo. Proteins upregulated in the early remyelination phase were involved in calcium binding, e.g. calretinin (>1.3 fold, p < 0.005), S10A5 and secretagogin, and involved in mitochondrial function, e.g. NADH-ubiquinone oxidoreductase chain 3, and acyl-coenzyme A synthetase. Calretinin, S10A5 and secretagogin expression levels were characterized using immunohistochemistry. Calretinin immunoreactivity was significantly increased (>3 fold, p = 0.016) in the medial septal nuclei of 1,25D treated mice in the early remyelination phase. Our results indicate that vitamin D may influence remyelination by mechanisms involving an increase in calretinin expression and potentially other calcium binding proteins.

  • Glutathione monoethyl ester prevents TDP-43 pathology in motor neuronal NSC-34 cells
    Neurochem. Int. (IF 3.262) Pub Date : 2017-08-14
    Tong Chen, Bradley J. Turner, Philip M. Beart, Lucy Sheehan-Hennessy, Chinasom Elekwachi, Hakan Muyderman

    Oxidative stress is recognised as central in a range of neurological diseases including Amyotrophic lateral sclerosis (ALS), a disease characterised by fast progressing death of motor neurons in the brain and spinal cord. Cellular pathology includes cytosolic protein aggregates in motor neurons and glia of which potentially cytotoxic hyper-phosphorylated fragments of the Transactive response DNA Binding Protein 43 kDa (TDP-43) constitute a major component. This is closely associated with an additional loss of nuclear TDP-43 expression indicating a “loss of function” mechanism, accelerating motor neuron (MN) loss. Furthermore, mutations in TDP-43 cause familial ALS and ALS-like disease in animal models. In this study, we investigated the role of glutathione (GSH) in modulating oxidative stress responses in TDP-43 pathology in motor neuron NSC-34 cells. Results demonstrate that depletion of GSH produces pathology similar to that of mutant TDP-43, including occurrence of cytosolic aggregates, TDP-43 phosphorylation and nuclear clearing of endogenous TDP-43. We also demonstrate that introduction of mutant TDP-43A315T and silencing of endogenous TDP-43, but not overexpression of wild-type TDP-43, result in similar pathology, including depletion of intracellular GSH, possibly resulting from a decreased expression of a regulatory subunit of ɣ-glutamylcysteine ligase (GCLM), a rate limiting enzyme in GSH synthesis. Importantly, treatment of mutant cells with GSH monoethyl ester (GSHe) that directly increases intracellular GSH and bypasses the need for GSH synthesis, protected against mutant-induced TDP-43 pathology, including reducing aggregate formation, nuclear clearance, reactive oxygen species (ROS) production and cell death. Our data strongly suggest that oxidative stress is central to TDP-43 pathology and may result from a loss of function affecting GSH synthesis and that treatments directly aimed at restoring cellular GSH content may be beneficial in preventing cell death in TDP-43-mediated ALS.

  • Antecedent ADHD, dementia, and metabolic dysregulation: A U.S. based cohort analysis
    Neurochem. Int. (IF 3.262) Pub Date : 2017-08-12
    Keith Fluegge, Kyle Fluegge

    Introduction Epidemiological and genetic studies have reported a link between antecedent ADHD and dementia. The underpinning mechanisms of these associations are not known and have generated considerable speculation. Methods We have extracted hospitalization discharge data on dementia and ADHD (representing a severe phenotype) from the Healthcare Cost and Utilization Project (HCUPnet) and utilized a Poisson regression with two-ways fixed effects to investigate this association. Results An unadjusted ten-year lagged measure of a severe ADHD phenotype increases hospitalization risk for an all-listed Lewy Body Dementia (LBD) diagnosis (IRR: 1.21, 95% C.I. 1.08–1.35) and Alzheimer's disease (AD) discharge diagnosis (IRR: 1.15, 95% C.I.: 1.05–1.27). However, these relationships may be dependent upon the extent of metabolic dysregulation in a subtype-specific manner, as controlling for diabetes removes the significant association between antecedent ADHD and risk of AD but not LBD. Discussion These results indicate that the association between antecedent ADHD and dementia risk may be uniquely influenced by metabolic dysregulation, building upon prior discussion in this journal of a purported link between AD and diabetes. We tie the current findings to environmental risk factors that we have previously implicated in the etiology of ADHD to generate testable hypotheses on the underlying brain neurochemistry that may facilitate the link between metabolic dysregulation and dementia subtype risk.

Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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