Oxidative stress on EAAC1 is involved in MPTP-induced glutathione depletion and motor dysfunction
Oxidative stress on EAAC1 is involved in MPTP-induced glutathione depletion and motor dysfunction
复制标题
DOI：
10.1111/j.1460-9568.2007.05979.x
复制
发表时间：
2008-01-01
影响因子：
3.4
通讯作者：
Nakaki, Toshio
中科院分区：
文献类型：
--
作者：
Aoyama, Koji;Matsumura, Nobuko;Nakaki, Toshio
兴奋性氨基酸载体1 （EAAC1）是一种在中枢神经系统成熟神经元上表达的谷氨酸转运蛋白，是摄取产生谷胱甘肽（GSH）所需的神经元半胱氨酸的主要途径。帕金森病（PD）是一种与氧化应激相关的神经退行性疾病，表现为黑质（SN）的谷胱甘肽耗竭。在此，我们报告了1-甲基-4-苯基-1,2,3,6-四氢吡啶（MPTP）处理的小鼠（PD的实验模型）表现出运动活性降低，GSH含量降低，EAAC1易位到膜上，硝化EAAC1水平升高。这些变化被预先服用n-乙酰半胱氨酸（NAC）逆转，NAC是一种膜渗透性半胱氨酸前体。7-硝基茚唑（一种特异性神经元一氧化氮合酶抑制剂）预处理也能抑制MPTP诱导的GSH消耗和硝基酪氨酸的形成。过氧化氢、l-天冬氨酸-羟肟酸或1-甲基-4-苯基吡啶预处理可减少中脑切片培养后半胱氨酸的增加。用二乙酸氯甲基荧光素（一种谷胱甘肽标志物）进行的研究表明，NAC处理后，SN中的多巴胺能神经元的谷胱甘肽水平升高。这些发现表明，MPTP诱导的氧化应激可能通过EAAC1功能障碍减少神经元半胱氨酸摄取，导致GSH合成受损，NAC可能通过维持多巴胺能神经元中GSH的水平，对MPTP神经毒性发挥保护作用。
Excitatory amino acid carrier 1 (EAAC1) is a glutamate transporter expressed on mature neurons in the CNS, and is the primary route for uptake of the neuronal cysteine needed to produce glutathione (GSH). Parkinson's disease (PD) is a neurodegenerative disorder pathogenically related to oxidative stress and shows GSH depletion in the substantia nigra (SN). Herein, we report that 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice, an experimental model of PD, showed reduced motor activity, reduced GSH contents, EAAC1 translocation to the membrane and increased levels of nitrated EAAC1. These changes were reversed by pre-administration of n-acetylcysteine (NAC), a membrane-permeable cysteine precursor. Pretreatment with 7-nitroindazole, a specific neuronal nitric oxide synthase inhibitor, also prevented both GSH depletion and nitrotyrosine formation induced by MPTP. Pretreatment with hydrogen peroxide, L-aspartic acid beta-hydroxamate or 1-methyl-4-phenylpyridinium reduced the subsequent cysteine increase in midbrain slice cultures. Studies with chloromethylfluorescein diacetate, a GSH marker, demonstrated dopaminergic neurons in the SN to have increased GSH levels after NAC treatment. These findings suggest that oxidative stress induced by MPTP may reduce neuronal cysteine uptake, via EAAC1 dysfunction, leading to impaired GSH synthesis, and that NAC would exert a protective effect against MPTP neurotoxicity by maintaining GSH levels in dopaminergic neurons.