Visualization of the antioxidative effects of melatonin at the mitochondrial level during oxidative stress-induced apoptosis of rat brain astrocytes
Visualization of the antioxidative effects of melatonin at the mitochondrial level during oxidative stress-induced apoptosis of rat brain astrocytes
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DOI：
10.1111/j.1600-079x.2004.00140.x
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发表时间：
2004-08-01
影响因子：
10.3
通讯作者：
Wen, ST
中科院分区：
文献类型：
--
作者：
Jou, MJ;Peng, TI;Wen, ST
氧化应激诱导的线粒体功能障碍已被证明在多种疾病的发病机制中发挥着至关重要的作用。因此，保护线粒体功能对于细胞在这些疾病过程中生存至关重要。在这项研究中，我们证明松果体的主要分泌产物褪黑激素可以很容易地将线粒体从氧化应激引起的功能障碍中拯救出来，并有效防止大鼠脑星形胶质细胞（RBA-1）随后的凋亡事件和死亡。通过应用延时常规、共焦和多光子荧光成像显微镜以及非侵入性线粒体靶向荧光探针，研究了褪黑激素在完整活细胞线粒体中提供的早期保护。特别是，我们观察到褪黑激素在早期时间点（10 分钟内）有效地防止了外源性施加 H2O2 诱导的大鼠脑星形胶质细胞线粒体肿胀，并随后减少了细胞凋亡（150 分钟后）。其他早期凋亡事件，例如磷脂酰丝氨酸的质膜暴露和早期凋亡细胞核的阳性 YOPRO-1 染色，也可以被褪黑激素预防。一项与褪黑激素提供的早期保护相关的线粒体水平的机制研究表明，吲哚分子显着减少了 H2O2 应激诱导的线粒体活性氧 (ROS) 形成。褪黑素还可以防止由其他有机氢过氧化物（包括叔丁基过氧化氢和异丙苯过氧化氢）引起的线粒体活性氧生成。褪黑素的这种抗氧化作用比维生素 E 更有效。通过其减少线粒体 ROS 生成的能力，褪黑素可以防止 H2O2 诱导的线粒体钙超载、线粒体膜电位去极化以及线粒体通透性转变 (MPT) 孔的打开。结果，褪黑素阻断了 MPT 依赖性细胞色素 c 的释放、下游 caspase 3 的激活、细胞核的浓缩和核碎裂以及细胞核 DNA 的凋亡断裂。因此，褪黑激素提供的强大线粒体保护增强了其对抗各种氧化应激诱导的线粒体功能障碍以及各种疾病中线粒体介导的细胞凋亡的治疗潜力。
Oxidative stress-induced mitochondrial dysfunction has been shown to play a crucial role in the pathogenesis of a wide range of diseases. Protecting mitochondrial function, therefore, is vital for cells to survive during these disease processes. In this study, we demonstrate that melatonin, a chief secretory product of the pineal gland, readily rescued mitochondria from oxidative stress-induced dysfunction and effectively prevented subsequent apoptotic events and death in rat brain astrocytes (RBA-1). The early protection provided by melatonin in mitochondria of intact living cells was investigated by the application of time-lapse conventional, confocal, and multiphoton fluorescent imaging microscopy coupled with noninvasive mitochondria-targeted fluorescent probes. In particular, we observed that melatonin effectively prevented exogenously applied H2O2-induced mitochondrial swelling in rat brain astrocytes at an early time point (within 10 min) and subsequently reduced apoptotic cell death (150 min later). Other early apoptotic events such as plasma membrane exposure of phosphatidyl serine and the positive YOPRO-1 staining of the early apoptotic nucleus were also prevented by melatonin. A mechanistic study at the mitochondrial level related to the early protection provided by melatonin revealed that the indole molecule significantly reduced mitochondrial reactive oxygen species (ROS) formation induced by H2O2 stress. Melatonin also prevented mitochondrial ROS generation caused by other organic hydroperoxides including tert-butyl hydroperoxide and cumene hydroperoxide. This antioxidative effect of melatonin is more potent than that of vitamin E. Via its ability to reduce mitochondrial ROS generation, melatonin prevented H2O2-induced mitochondrial calcium overload, mitochondrial membrane potential depolarization, and the opening of the mitochondrial permeability transition (MPT) pore. As a result, melatonin blocked MPT-dependent cytochrome c release, the downstream activation of caspase 3, the condensation and karyorrhexis of the nucleus and apoptotic fragmentation of nuclear DNA. Thus, the powerful mitochondrial protection provided by melatonin reinforces its therapeutic potential to combat a variety of oxidative stress-induced mitochondrial dysfunctions as well as mitochondria-mediated apoptosis in various diseases.