Isolated Cerebral and Cerebellar Mitochondria Produce Free Radicals when Exposed to Elevated Ca2+ and Na+: Implications for Neurodegeneration
Isolated Cerebral and Cerebellar Mitochondria Produce Free Radicals when Exposed to Elevated Ca2+ and Na+: Implications for Neurodegeneration
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DOI：
10.1046/j.1471-4159.1994.63020584.x
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发表时间：
1994-08
影响因子：
4.7
通讯作者：
J. Dykens
中科院分区：
文献类型：
--
作者：
J. Dykens
摘要：证据是令人信服的，自由基，加上增加游离胞质Ca 2+和Na+，数字显着暴露于谷氨酸和二羧酸兴奋毒素，如NMDA和红藻氨酸后的神经元死亡。然而，无论是这些自由基的来源，也没有钙离子动员和自由基的生产之间的直接联系已被很好地定义。本文报告的电子顺磁共振研究表明，在常氧条件下，当暴露于2.5 µM Ca 2+、14 mM Na+和升高的ADP时，从成年大鼠大脑皮层和小脑分离的完整线粒体产生极具反应性的羟基（·OH）自由基，以及抗坏血酸和其他碳中心自由基，这些条件在兴奋性毒素诱导的神经变性期间在神经元的细胞质中普遍存在。在前馈循环中，分离的线粒体暴露于·OH显著增加随后以琥珀酸为底物的自由基产生5至16倍（平均值= 8.8 ± 1.6 SE，n = 6，p > 0.01），并且还选择性地损害NADH-CoQ脱氢酶活性（电子传递复合物1）的功能。这些影响也反映在呼吸速率降低48%与复合物1基板，但增加27%与复合物2基板，后·OH暴露。在从帕金森病患者的黑质、从亨廷顿病患者的血小板和从阿尔茨海默病患者的新皮层分离的线粒体中观察到相当的复合物1功能障碍。线粒体自由基的产生提供了一个可测试的模型，基于氧自由基毒性，氧化酶失活，和线粒体功能障碍，兴奋性毒性过程中的神经元坏死的最终共同途径，并在一个主机的神经退行性疾病。
Abstract: The evidence is compelling that free radicals, plus increases in free cytosolic Ca2+ and Na+, figure prominently in neuronal death after exposure to glutamate and dicarboxylic excitotoxins such as NMDA and kainate. However, neither the source of these radicals nor the direct connection between Ca2+ mobilization and radical production has been well defined. Electron paramagnetic resonance studies reported here indicate that intact mitochondria isolated from adult rat cerebral cortex and cerebellum generate extremely reactive hydroxyl (•OH) radicals, plus ascorbyl and other carbon‐centered radicals when exposed to 2.5 µM Ca2+, 14 mM Na+, plus elevated ADP under normoxic conditions, circumstances that prevail in the cytoplasm of neurons during excitotoxin‐induced neurodegeneration. In a feed‐forward cycle, exposure of isolated mitochondria to •OH significantly increases subsequent radical production five‐ to 16‐fold (average = 8.8 ± 1.6 SE, n = 6, p > 0.01) with succinate as substrate, and also selectively impairs function of NADH‐CoQ dehydrogenase activity (electron transport complex 1). These effects are also reflected by respiration rates that are reduced 48% with complex 1 substrates, but increased 27% with complex 2 substrate, after •OH exposure. Comparable complex 1 dysfunction is observed in mitochondria isolated from the substantia nigra of Parkinson's disease patients, from platelets of Huntington's disease patients, and from neocortex of Alzheimer's disease patients. Mitochondrial radical production provides a testable model, based on oxyradical toxicity, oxidative enzyme inactivation, and mitochondrial dysfunction, for the final common pathway of neuronal necrosis during excitotoxicity, and in a host of neurodegenerative disorders.