Hyperammonemia associated with overt hepatic encephalopathy (OHE) causes excitotoxic neuronal death through activation of the cytochrome C (CytC)-mediated mitochondria-dependent apoptotic pathway. We tested the therapeutic effect of nortriptyline (NT), a mitochondrial permeability transition pore (mPTP) blocker that can possibly inhibit mitochondrial CytC efflux to the cytosol on in vivo and in vitro OHE models. After ensuring the generation of OHE rats, established by bile duct ligation (BDL), they were intraperitoneally administered either 20 mg/kg NT (i.e., BDL+NT) or another vehicle (i.e., BDL+VEH) for 14 days. Compared with the control, BDL+VEH showed an increment of motor deficits, cell death, synaptic loss, apoptosis, and mitochondria with aberrant morphology in substantia nigra compacta dopaminergic (DA-ergic) neurons. However, the extent was significantly reversed in BDL+NT. Subsequently, we studied the neuroprotective mechanism of NT using PC-12 cells, a DA-ergic cell line, which exposed glutamate used as an excitotoxin. Compared with the control, the cells exposed to 15 mM glutamate (i.e., GLU) showed incremental cell death, apoptosis, and demise in mitochondrial respiration. Importantly, efflux of CytC from mitochondria to cytosol and the dissipation of mitochondrial membrane potential (△Ψm), an indicator of mPTP opening, were prominent in GLU. However, compared with the GLU, the cells cotreated with 10 μM NT (i.e., GLU+NT) showed a significant reduction in the aforementioned phenomenon. Together, we concluded that NT can be used for OHE therapeutics, mitigating the excitotoxic death of substantia nigra compacta DA-ergic neurons via mPTP-associated mitochondrial dysfunction inhibition.

中文翻译：

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去甲替林通过减轻线粒体功能障碍对明显肝性脑病的神经保护作用。

与明显肝性脑病 (OHE) 相关的高氨血症通过激活细胞色素 C (CytC) 介导的线粒体依赖性细胞凋亡途径导致兴奋性毒性神经元死亡。我们测试了去甲替林 (NT) 的治疗效果，它是一种线粒体通透性转换孔 (mPTP) 阻断剂，可能在体内和体外 OHE 模型上抑制线粒体 CytC 流出到细胞质。在确保通过胆管结扎（BDL）建立OHE大鼠的产生后，对它们腹膜内施用20mg/kg NT（即BDL+NT）或另一种载体（即BDL+VEH）14天。与对照组相比，BDL+VEH 显示黑质致密多巴胺能 (DA 能) 神经元运动缺陷、细胞死亡、突触损失、细胞凋亡和线粒体形态异常增加。然而，BDL+NT 的程度却显着逆转。随后，我们使用 PC-12 细胞（一种 DA 能细胞系）研究了 NT 的神经保护机制，该细胞暴露了用作兴奋毒素的谷氨酸。与对照相比，暴露于 15 mM 谷氨酸（即 GLU）的细胞显示出细胞死亡、细胞凋亡和线粒体呼吸消亡的增加。重要的是，CytC 从线粒体到细胞质的流出和线粒体膜电位 (△Ψm) 的耗散（mPTP 打开的指标）在 GLU 中很突出。然而，与GLU相比，用10μM NT（即GLU+NT）共处理的细胞显示出上述现象显着减少。总之，我们得出结论，NT 可用于 OHE 治疗，通过 mPTP 相关的线粒体功能障碍抑制来减轻黑质致密 DA 能神经元的兴奋毒性死亡。