Visualization of melatonin's multiple mitochondrial levels of protection against mitochondrial Ca2+-mediated permeability transition and beyond in rat brain astrocytes
Visualization of melatonin's multiple mitochondrial levels of protection against mitochondrial Ca2+-mediated permeability transition and beyond in rat brain astrocytes
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DOI：
10.1111/j.1600-079x.2009.00721.x
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发表时间：
2010-01-01
影响因子：
10.3
通讯作者：
Chen, Chun-Chia
中科院分区：
文献类型：
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作者：
Jou, Mei-Jie;Peng, Tsung-I;Chen, Chun-Chia
褪黑激素保护细胞免受各种类型的氧化应激诱导的细胞凋亡，主要是由于其能够有效地抑制病理和疾病状况增强的线粒体活性氧（mROS）的产生。一旦产生，mROS不加区别地损害线粒体组分，更重要的是，它们直接激活线粒体通透性转换（MPT），这是启动线粒体凋亡后信号传导的关键机制之一。然而，褪黑激素是否直接靶向MPT仍不确定，特别是在氧化应激期间。因此，这项研究，调查了这种可能性的“无氧化钙应激”的存在下，维生素E作为唯一的钙离子介导的MPT暴露后，以排除褪黑激素的主要抗氧化作用，以及钙离子介导的氧化应激。使用培养的大鼠脑星形胶质细胞RBA-1进行研究。随着激光扫描多重荧光成像显微镜的应用，我们可视化的第一次提供的褪黑激素在Ca2+胁迫的多重线粒体保护作用。首先，褪黑激素，由于其主要的抗氧化作用，完全防止mCa2+诱导的mROS形成在离子霉素曝光。其次，当褪黑素的抗氧化作用由于添加维生素E而被阻止时，褪黑素显著地阻止了mCa 2+介导的MPT和细胞凋亡，这表明其直接靶向MPT。令人惊讶的是，在环孢菌素A（MPT抑制剂）存在下，褪黑激素在离子霉素暴露期间进一步降低了mCa2+介导的细胞凋亡，这也表明其靶向作用超出了MPT。由于星形胶质细胞积极参与调节CNS中的突触传递和神经血管偶联，因此由褪黑激素提供的针对星形胶质细胞中的mCa 2 +-和/或mROS-介导的凋亡的这些多个线粒体层的保护对于将来治疗性预防和治疗CNS中的星形胶质细胞介导的神经变性疾病可能是至关重要的。
Melatonin protects cells against various types of oxidative stress-induced apoptosis due primarily to its ability to effectively scavenge pathological and disease condition-augmented generation of mitochondrial reactive oxygen species (mROS). Once produced, mROS indiscriminately damage mitochondrial components and more importantly they crucially activate directly the mitochondrial permeability transition (MPT), one of the critical mechanisms for initiating post mitochondrial apoptotic signaling. Whether or not melatonin targets directly the MPT, however, remains inconclusive, particularly during oxidative stress. This study, thus, investigated this possibility of an 'oxidation free Ca2+ stress' in the presence of vitamin E after ionomycin exposure as a sole Ca2+-mediated MPT in order to exclude melatonin's primary antioxidative effects as well as Ca2+-mediated oxidative stress. The studies were carried out using cultured rat brain astrocytes RBA-1. With the application of laser scanning multiple fluorescence imaging microscopy, we visualized for the first time multiple mitochondrial protective effects provided by melatonin during Ca2+ stress. First, melatonin, due to its primary antioxidative actions, completely prevented mCa2+-induced mROS formation during ionomycin exposure. Secondly, when melatonin's antioxidative effects were prevented due to the addition of vitamin E, melatonin significantly prevented mCa2+-mediated MPT and apoptosis suggesting its direct targeting of the MPT. Surprisingly, in the presence of cyclosporin A, a MPT inhibitor, melatonin reduced further mCa2+-mediated apoptosis during ionomycin exposure also suggesting its targeting beyond the MPT. As astrocytes are actively involve in regulating synaptic transmission and neurovascular coupling in the CNS, these multiple mitochondrial layers of protection provided by melatonin against mCa2+-and/or mROS-mediated apoptosis in astrocytes may be crucial for future therapeutic prevention and treatment of astrocyte-mediated neurodegenerative diseases in the CNS.