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

项目概要/摘要 缺血性脑损伤的治疗效果不佳，部分原因是我们的了解有限 导致神经元损失的机制。虽然过量谷氨酸的贡献 释放和神经元 Ca2 积累已经进行了大量研究，最近的证据 暗示另一种二价阳离子 Zn2 的关键贡献。缺血后或 长时间的癫痫发作，游离 Zn2 在神经元中积累，并且观察到 Zn2 螯合作用具有保护作用，在神经元死亡中发挥作用。文化研究表明 外源施加的Zn2可以进入神经元并在线粒体中积累， 强烈扰乱它们的功能。然而，人们对损伤机制知之甚少 由内源性 Zn2 在天然脑组织中积累引起。 使用经过氧糖剥夺（OGD）的急性海马切片 为了模拟缺血模型，我们最近首次同时测量了细胞质 Zn2和Ca2变化，发现Zn2积累是早期事件 海马锥体神经元，先于后续细胞并对其做出贡献 死亡。 Zn2 的这些急性有害作用似乎是由 Zn2 造成的 通过线粒体 Ca2 单向转运蛋白 (MCU) 摄取到线粒体中。拟议的 研究围绕一个假设进行：Zn2 有助于早期阶段 缺血性神经元损伤，部分是通过进入并诱导急性破坏 线粒体功能。本研究的主要目标是进行早期评估 这一假设在体内，使用已建立的全脑缺血模型 由窒息导致的心脏骤停。目标 我将使用心脏骤停模型 描述不同细胞中 Zn2 和线粒体依赖性变化和神经元损伤的特征 大脑区域，作为缺血持续时间和恢复持续时间的函数 评估之前。目标 II 将测试一系列针对急性和慢性疾病的干预措施 Ca2 和 Zn2 的亚急性作用，单独或联合施用 根据我们的海马切片研究表明，我们预测将废除某些 个人干预的缺点。他们将在之前交付 缺血，或仅在再灌注时评估延迟获益的潜力 行政管理。这些研究将在令人信服的机制之间架起一座桥梁 来自体外研究和努力打造更好的退化疗法的线索 体内缺血后，我们希望它们能够阐明新型 干预措施可在缺血急性期或缺血后进行 再灌注，这将破坏病理级联，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.