Cerebellar malfunction and damage during ischemia

这项建议的主要目标是调查可能涉及小脑损伤的机制 和脑缺血时的功能障碍脑缺血，发生在心脏骤停、中风和 围产期窒息是死亡和长期残疾的主要原因。小脑是一个常见的目标 小脑浦肯野细胞是最易受缺血性损伤的脑细胞之一。 然而，关于浦肯野细胞如何对缺血作出反应以及如何被缺血损伤的知识相对较少。这 缺乏信息是一个问题，因为许多缺血机制在其他大脑中运作， 区域涉及分子过程，这些分子过程要么不表达，要么具有不寻常的构型， 浦肯野细胞。对于该提议，将使用脑切片模型来模拟体外脑缺血， 膜片钳记录、共聚焦荧光成像和药理学操作将用于 探讨小脑缺血性损伤机制。模拟缺血诱导严重的去极化 浦肯野细胞，这是通过激活非NMDA离子型谷氨酸受体介导的（和可能 其它谷氨酸受体/转运蛋白），但其发作被GABAA受体的激活延迟。这些 电生理反应与广泛的组织肿胀和随后的 坏死和凋亡性细胞死亡的发展与体内模型中观察到的非常相似。模拟 局部缺血还严重破坏通过小脑的电信号传导， 在局部缺血发作终止后持续很长一段时间。确定其机制 细胞损伤和中断的信号处理都应该为发展提供有用的信息 治疗方法。本提案的具体目标是：1）确定导致谷氨酸的机制 在浦肯野细胞周围的积累，阐明哪些受体介导浦肯野细胞反应， 确定它们对细胞损伤的贡献; 2）确定GABAA受体 激活延迟浦肯野细胞去极化的开始，并确定延迟是否有益或 破坏性的;和3）确定电信号在小脑电路中的位置以及通过什么机制 转导被破坏。

The primary goal of this proposal is to investigate mechanisms that may be involved in cerebellar damage and malfunction during brain ischemia. Brain ischemia, which occurs during cardiac arrest, stroke and perinatal asphyxia, is a leading cause of death and long term disability. The cerebellum is a frequent target of stroke, and cerebellar Purkinje cells are one of the most susceptible brain cells to ischemic damage. However, relatively little is known about how Purkinje cells respond to and are damaged by ischemia. This lack of information is problematic because many of the ischemic mechanisms operating in other brain regions involve molecular processes that are either not expressed or have an unusual configuration in Purkinje cells. For this proposal, a brain slice model will be used to simulate brain ischemia in vitro and patch-clamp recording, confocal fluorescence imaging and pharmacological manipulations will be used to investigate mechanisms of cerebellar ischemic damage. Simulated ischemia induces a severe depolarization of Purkinje cells which is mediated by activation of non-NMDA ionotropic glutamate receptors (and possibly other glutamate receptors/transporters) but its onset is delayed by activation of GABAA receptors. These electrophysiological responses are associated with extensive tissue swelling and the subsequent development of necrotic and apoptotic cell death very similar to that observed with in vivo models. Simulated ischemia also severely disrupts electrical signal transduction through the cerebellum and the disruption persists for long periods after the ischemic episode is terminated. Determining the mechanisms that underlie both cellular damage and disrupted signal processing should provide useful information for the development of therapies. The specific aims of this proposal are: 1) To determine the mechanisms that lead to glutamate accumulation around Purkinje cells, elucidate which receptors mediate the Purkinje cell response and determine their contribution to cell damage; 2) To determine the mechanisms by which GABAA receptor activation delays the onset of Purkinje cell depolarization and to determine if the delay is beneficial or damaging; and 3) To determine where in the cerebellar circuitry and by what mechanism electrical signal transduction is disrupted.