Mitochondrial Zn2+ in ischemic neurodegeneration: In vivo tests of principle studies in a rat cardiac arrest model

项目摘要/摘要 缺血性脑损伤的治疗很差，部分原因是我们的认识有限 导致神经元丧失的机制。而过量谷氨酸的贡献 最近的证据表明，钙离子的释放和神经元内钙的积累已经被大量研究。 暗示了另一种二价阳离子，锌离子的临界贡献。在缺血后或 持续的癫痫发作，游离锌离子在神经元中积累，并观察到锌离子 螯合是保护性的，在神经元死亡中起着一定的作用。文化研究揭示了 外源施加的锌离子可以进入神经元并在线粒体中积累， 有力地扰乱了它们的功能。然而，人们对损伤的机制知之甚少。 这是由于内源性锌离子在天然脑组织中的积累所致。 应用急性缺氧缺糖(OGD)大鼠海马脑片 模型缺血，我们最近首次同时测量了胞浆 锌离子和钙离子的变化，发现锌离子的积累是一个早期事件 海马锥体神经元，先于后继细胞并对其作出贡献 死亡。锌离子的这些急性有害效应似乎是由锌离子引起的。 通过线粒体钙离子单一转运体(MCU)进入线粒体。建议数 研究围绕着一个假设进行：锌离子参与了癌症的早期阶段 缺血性神经元损伤，部分是通过进入和诱导急性脑损伤 线粒体功能。这项研究的主要目标是及早对 这一假说在活体内，使用已建立的全脑缺血模型 是由窒息心脏骤停引起的。Aim I将使用心脏骤停模型 不同脑区锌离子和线粒体依赖性变化及神经元损伤的特征 脑区域，作为缺血持续时间和恢复持续时间的函数 在评估之前。AIM II将测试一些针对急性和非传染性疾病的干预措施 单独或联合应用钙、锌离子的亚急性效应 我们的海马片研究表明，我们预测将消除某些 个人干预的不足之处。它们将在之前交付 缺血，或仅在再灌注时评估延迟治疗的潜在益处 行政管理。这些研究将在令人信服的机械论 来自体外研究和努力打造更好的退行性疾病治疗方法的线索 在体内缺血后，我们希望它们将导致阐明新类型的 干预措施，在缺血急性期或 再灌流，这将扰乱病理级联反应，从而改善结果。

Project Summary/Abstract Therapy for ischemic brain injury is poor in part because of our limited understanding of mechanisms leading to neuronal loss. While contributions of excessive glutamate release and neuronal Ca2+ accumulation have been much studied, recent evidence implicates critical contributions of another divalent cation, Zn2+. After ischemia or prolonged seizures, free Zn2+ accumulates in neurons, and observations that Zn2+ chelation is protective implicates a role in neuronal death. Culture studies have revealed that exogenously applied Zn2+ can enter neurons and accumulate in mitochondria, powerfully disrupting their function. However, little is known about mechanisms of injury caused by the accumulation of endogenous Zn2+ in native brain tissues. Using acute hippocampal slices subjected to oxygen glucose deprivation (OGD) to model ischemia, we recently made the first simultaneous measurements of cytosolic Zn2+ and Ca2+ changes, and found that Zn2+ accumulation is an early event in hippocampal pyramidal neurons, that precedes and contributes to subsequent cell death. These acute deleterious effects of Zn2+ appear to result specifically from Zn2+ uptake into mitochondria via the mitochondrial Ca2+ uniporter (MCU). The proposed studies are organized around a Hypothesis: Zn2+ contributes to the early stages of ischemic neuronal injury, in part via entering and inducing acute disruption of mitochondrial function. The primary goal of this study is to make an early assessment of this hypothesis in vivo, using of an established model of global cerebral ischemia resulting from asphyxial cardiac arrest. Aim I will use the cardiac arrest model to characterize Zn2+ and mitochondrial dependent changes and neuronal injury in different brain regions, as a function of both the duration of ischemia and the duration of recovery prior to assessment. Aim II will test a number of interventions targeting acute and subacute effects of Ca2+ and Zn2+, administered either alone or in combinations as suggested by our hippocampal slice studies, that we predict will abrogate certain shortcomings of the individual interventions. They will be delivered either before ischemia, or only upon reperfusion to assess potential for benefit with delayed administration. These studies will provide a bridge between compelling mechanistic clues derived from in vitro studies and efforts to forge better therapies for degeneration after in vivo ischemia, and we hope that they will lead to the elucidation of new types of interventions, to be delivered either during the acute phase of ischemia or upon reperfusion, that will disrupt the pathological cascade, enabling improved outcomes.