Elsevier

Behavioural Brain Research

Volume 416, 7 January 2022, 113546
Behavioural Brain Research

Ayahuasca, a psychedelic beverage, modulates neuroplasticity induced by ethanol in mice

https://doi.org/10.1016/j.bbr.2021.113546Get rights and content

Highlights

  • Ayahuasca attenuated EIBS.

  • Ayahuasca reduced anxiogenic response to ethanol withdrawal.

  • Ayahuasca prevented the ethanol induced changes on 5HT1a receptor and prodynorphin levels in hippocampus.

  • Ayahuasca reduced ethanol effects in the dynorphin/prodynorphin ratio in the striatum.

  • Ayahuasca has a potential application to modulate neuroplastic changes induced by ethanol.

Abstract

Alcohol use disorder needs more effective treatments because relapse rates remain high. Psychedelics, such as ayahuasca, have been used to treat substance use disorders. Our study aimed to evaluate the effects of ayahuasca on ethanol-induced behavioral sensitization (EIBS). Swiss mice received 2.2 g/kg ethanol or saline IP injections every other day across nine days (D1, D3, D5, D7, and D9), and locomotor activity was evaluated 10 min after each injection. Then, animals were treated daily with ayahuasca (corresponding to 1.76 mg/kg of N,N-dimethyltryptamine, DMT) or water by oral gavage for eight consecutive days. On the seventh day, mice were evaluated in the elevated plus maze. Then, mice were challenged with a single dose of ethanol to measure their locomotor activity. Dopamine receptors, serotonin receptors, dynorphin, and prodynorphin levels were quantified in the striatum and hippocampus by blot analysis. Repeated ethanol administration resulted in EIBS. However, those animals treated with ayahuasca had an attenuated EIBS. Moreover, ayahuasca reduced the anxiogenic response to ethanol withdrawal and prevented the ethanol-induced changes on 5-HT1a receptor and prodynorphin levels in the hippocampus and reduced ethanol effects in the dynorphin/prodynorphin ratio levels in the striatum. These results suggest a potential application of ayahuasca to modulate the neuroplastic changes induced by ethanol.

Introduction

Although ethanol is a licit drug, it is associated with high morbidity and mortality. Ethanol abuse is responsible for about 3 million deaths per year worldwide, being associated with more than 200 diseases, such as cancer, cardiovascular and liver diseases, and traffic injuries, aggression, and homicides [1]. The prevalence of current drinkers differs among regions, reaching 54.1 % in the Americas and 59.9 % in Europe. Therefore, alcohol use disorder (AUD) is most prevalent in these regions (Americas – 4.1 %; Europe – 3.7 %) [1]. AUD is the uncontrolled use of ethanol despite the absence or reduction of pleasant effects and the awareness of the harm caused by its repeated administration [2]. Ethanol withdrawal may lead to symptoms of anxiety, depression, and irritability that act as a negative reinforcement for the continued use of the drug [3], whose mechanism involves “drinking-to-cope”, a process related to negative effect. Treatments available to AUD are based on psychosocial and pharmacological therapies. The psychosocial tools include individual, group and family therapies, and the pharmacological therapies include treatment of the alcohol withdrawal symptoms (anxiolytics and antidepressants) and specific therapies that cause aversion to ethanol (disulfiram) or craving reduction (naltrexone). Thus, treatments are scarce, and relapse occurs in more than half of the patients with AUD [4], being even higher for patients with co-occurring anxiety disorder [5].

In this context, psychedelic substances have been widely studied as possible therapeutic strategies for addiction treatment. Ayahuasca (AYA) is a psychoactive beverage originally from the Amazon Indians used in religious rituals such as Santo Daime and Barquinha [6]. AYA is prepared by the decoction of the leaves of Psychotria viridis, which contain the hallucinogenic substance N,N-dimethyltryptamine (DMT), and Banisteriopsis caapi vines, whose main constituents are β-carbolines alkaloids, such as harmine (HRM), harmaline (HRL), and tetrahydroharmine (THH). The synergistic effect of both plants is explained by the monoamine oxidase type A inhibition of the β-carbolines alkaloids, which allows DMT absorption by oral administration [7,8]. Clinical studies have shown the beneficial effects of AYA in the treatment of depression, anxiety, and addiction [[9], [10], [11], [12], [13], [14]]. Preclinical studies also showed that AYA compounds, such as harmine and others β-carbolines, induced anxiolytic and antidepressant-like effects; however, chronic exposure to AYA tea did not affect anxiety and memory in mice [[15], [16], [17]].

DMT has a similar chemical structure to serotonin and is a partial agonist at 5-HT1a, 5-HT1b, 5-HT2a, and 5-HT2c receptors [18], whereas THH blocks serotonin reuptake, increasing serotonin levels in the brain [19]. Ethanol interferes in the dopaminergic, serotonergic, and opioid systems [20,21] leading to high dopamine levels in the nucleus accumbens, mainly mediated by D1 receptor, and increasing serotonin receptor expression [[22], [23], [24]]. Dynorphin, whose precursor is prodynorphin, is a potent endogenous opioid that acts preferentially on κ-opioid receptors. Studies indicate that dynorphin and κ receptors are involved in several psychiatric disorders, including anxiety, depression and addiction [[25], [26], [27], [28]]. Both chronic and acute exposure to ethanol produce neuroplasticity in the opioid system that reflect changes in the levels, expression and activity of dynorphin and κ receptors [[29], [30], [31]].

The ethanol-induced behavioral sensitization (EIBS) is a phenomenon associated with neuroadaptation induced by ethanol [20]. It can be measured by the enhancement of locomotor activity following chronic or intermittent ethanol exposure and is divided in two phases: acquisition or development and expression. Acquisition phase is characterized by immediate molecular and cellular changes mainly in the prefrontal cortex and in the ventral tegmental area [32,33]. The expression phase is related to the long-lasting consequences of these effects and the main substrate is the nucleus accumbens In general, the sensitization expression is revealed after a period of drug withdrawal upon a challenge administration [32]. Thus, this study aimed to evaluate the effects of AYA on EIBS and in anxiety, one of the main symptoms of the ethanol withdrawal, and to investigate if AYA modulates dopamine (D1, D2) and serotonin (5-HT1a, 5-HT2a) receptors, and dynorphin and prodynorphin levels.

Section snippets

Animals

Seventy-two adult male Swiss mice (6–7 weeks-old) were housed in polypropylene cages (26 × 36 × 19 cm) with free access to food and water. They were housed in a room with constant temperature (22 ± 1 °C) on a 12:12 h light/dark cycle (lights on at 7:00 am). All experiments were performed during the light period and the behavioral experiments were conducted between 7:30 am and 12 pm. One animal died during the experiments (SAL/AYA/ET group). The experimental procedures were approved by the

Alkaloid levels in AYA

Table 1 shows values of HRL, HRM, THH, and DMT concentration in lyophilized AYA.

Effect of AYA on EIBS

Locomotor activity during habituation showed no significant differences among the groups (data not shown). ANOVA repeated measures revealed a significant time effect (F4,236 = 5.60, p < 0.001) and treatment × time interaction (F4,236 = 3.69; p < 0.001; Fig. 2A) during the acquisition phase. Animals from the ethanol group showed significantly increased locomotor activity when compared with saline group on all days

Discussion

A clinical study has indicated that AYA, in a religious context, has been effective as a treatment for drug addiction [46]. However, more preclinical studies are required for a better understanding of the effects of AYA. We found that oral administration of AYA during eight consecutive days at a dose of 1.76 mg DMT/kg was effective to attenuate the expression of ethanol-induced behavioral sensitization in mice. We also observed that AYA caused an anxiolytic effect during ethanol withdrawal,

CRediT authorship contribution statement

Carolina Aparecida Faria Almeida: Conceptualization, Methodology, Validation, Formal analysis, Data curation, Writing - original draft, Writing - review & editing, Investigation, Visualization. Antonio Alves Pereira-Junior: Investigation. Jéssica Gonçalves Rangel: Investigation. Bruna Pinheiro Pereira: Investigation. Karla Cristinne Mancini Costa: Investigation. Vitor Bruno: Investigation, Writing - review & editing. Gabriela Oliveira Silveira: Investigation, Writing - original draft, Writing -

Declaration of Competing Interest

None.

Acknowledgments

The authors gratefully acknowledge the technical support of Marcos Vinícios Salles Dias, Lidia Emmanuela Wiazowski Spelta, and Camila Martins Chaves. This study received funding by the Fundação de Amparo à Pesquisa do Estado de Minas Gerais, Brazil (FAPEMIG, grant number APQ-01145-16), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior- Brasil (CAPES, Finance Code 001); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, grant numbers 405353/2016-2 and 141878/2020-7);

References (71)

  • S. Lindholm et al.

    Repeated ethanol administration induces short- and long-term changes in enkephalin and dynorphin tissue concentrations in rat brain

    Alcohol

    (2000)
  • S. Pellow et al.

    Validation of open: closed arm entries in an elevated plus-maze as a measure of anxiety in the rat

    J. Neurosci. Methods

    (1985)
  • C. Kliethermes et al.

    Pharmacological and genetic influences on hole-board behaviors in mice

    Pharmacol. Biochem. Behav.

    (2006)
  • M. YONAMINE et al.

    Solid-phase micro-extraction–gas chromatography–mass spectrometry and headspace-gas chromatography of tetrahydrocannabinol, amphetamine, methamphetamine, cocaine and ethanol in saliva samples

    J. Chromatogr. B.

    (2003)
  • L.H. Torres et al.

    Exposure to tobacco smoke during the early postnatal period modifies receptors and enzymes of the endocannabinoid system in the brainstem and striatum in mice

    Toxicol. Lett.

    (2019)
  • R. Camarini et al.

    Social factors in ethanol sensitization

    Int. Rev. Neurobiol.

    (2018)
  • J.B. Santos-Rocha et al.

    Involvement of neuronal nitric oxide synthase in cross-sensitization between chronic unpredictable stress and ethanol in adolescent and adult mice

    Alcohol

    (2018)
  • A.J. Oliveira-Lima et al.

    Effects of ayahuasca on the development of ethanol-induced behavioral sensitization and on a post-sensitization treatment in mice

    Physiol. Behav.

    (2015)
  • A.N. Sharma et al.

    Chronic progesterone treatment augments while dehydroepiandrosterone sulphate prevents tolerance to ethanol anxiolysis and withdrawal anxiety in rats

    Eur. J. Pharmacol.

    (2007)
  • B. Przewłocka et al.

    Ethanol withdrawal enhances the prodynorphin system activity in the rat nucleus accumbens

    Neurosci. Lett.

    (1997)
  • A.C. Burton et al.

    From ventral-medial to dorsal-lateral striatum: neural correlates of reward-guided decision-making

    Neurobiol. Learn. Mem.

    (2015)
  • WHO

    Global Status Report on Alcohol and Health 2018

    (2018)
  • G.F. Koob et al.

    Neurocircuitry of addiction

    Neuropsychopharmacology

    (2010)
  • A.P.S. Pires et al.

    Ayahuasca: A review of pharmacological and toxicological aspects | Ayahuasca: Uma revisão dos aspectos farmacológicos e toxicológicos

    Rev. Ciencias Farm. Basica e Apl.

    (2010)
  • J.C. Callaway et al.

    Ayahuasca preparations and serotonin reuptake inhibitors: a potential combination for severe adverse interactions

    J. Psychoactive Drugs

    (1998)
  • J.C. Bouso et al.

    Personality, psychopathology, life attitudes and neuropsychological performance among ritual users of ayahuasca: a longitudinal study

    PLoS One

    (2012)
  • E. Argento et al.

    Exploring ayahuasca-assisted therapy for addiction: a qualitative analysis of preliminary findings among an Indigenous community in Canada

    Drug Alcohol Rev.

    (2019)
  • F. Palhano-Fontes et al.

    Rapid antidepressant effects of the psychedelic ayahuasca in treatment-resistant depression: a randomized placebo-controlled trial

    Psychol. Med.

    (2019)
  • N.L. Galvão-Coelho et al.

    Changes in inflammatory biomarkers are related to the antidepressant effects of Ayahuasca

    J. Psychopharmacol.

    (2020)
  • R.N. de Almeida et al.

    Modulation of serum brain-derived neurotrophic factor by a single dose of Ayahuasca: observation from a randomized controlled trial

    Front. Psychol.

    (2019)
  • N.F. Correa-Netto et al.

    Chronic intermittent exposure to ayahuasca during aging does not affect memory in mice

    Braz. J. Med. Biol. Res.

    (2017)
  • L.M. Lima et al.

    Ayahuasca central nervous system effects: behavioral study

    Arztezeitschrift Fur Naturheilverfahren Und Regul.

    (2006)
  • D.J. McKenna et al.

    The scientific investigation of ayahuasca: a review of past and current research

    Heffer Rev. Psychedelic Res.

    (1998)
  • A.M. Erdozain et al.

    Neurobiological alterations in alcohol addiction: a review

    Adicciones

    (2014)
  • S.L. Morzorati et al.

    Comparison of VTA dopamine neuron activity in lines of rats selectively bred to prefer or avoid alcohol

    Alcohol. Clin. Exp. Res.

    (2006)
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