Cerebellar malfunction and damage during ischemia

这项建议的主要目标是研究可能与小脑损伤有关的机制。 以及脑缺血时的功能障碍。脑缺血，发生在心脏骤停、中风和 围产期窒息是导致死亡和长期残疾的主要原因。小脑是一个常见的靶子。 小脑浦肯野细胞是最容易受到缺血性损伤的脑细胞之一。 然而，对于浦肯野细胞如何对缺血做出反应并受到损伤，人们知之甚少。这 缺乏信息是有问题的，因为许多缺血机制在其他大脑中运作 区域涉及分子过程，这些过程要么没有表达，要么在 浦肯野细胞。对于这一建议，将使用脑片模型来模拟体外脑缺血和 膜片钳记录、共聚焦荧光成像和药物操作将用于 探讨小脑缺血性损伤的机制。模拟缺血引起严重的去极化 通过激活非NMDA型离子型谷氨酸受体(可能还有 其他谷氨酸受体/转运体)，但由于GABAA受体的激活而延迟起效。这些 电生理反应与广泛的组织肿胀和随后的 坏死性和凋亡性细胞死亡的发展与体内模型观察到的非常相似。模拟的 缺血还会严重干扰通过小脑的电信号转导，并破坏 在缺血发作终止后持续很长一段时间。确定构成基础的机制 细胞损伤和信号处理中断都应该为发展提供有用的信息 各种治疗方法。这项提议的具体目的是：1)确定导致谷氨酸的机制 在浦肯野细胞周围积聚，阐明哪些受体介导浦肯野细胞反应和 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 损害；以及3)确定小脑回路中的位置以及通过什么机制发出电信号 信号转导中断。

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.