Cerebellar malfunction and damage during ischemia

描述（由申请人提供）：“本提案的主要目标是研究脑缺血期间可能涉及小脑损伤和功能障碍的机制。在心脏骤停、中风和围产期窒息期间发生的脑缺血是导致死亡和长期残疾的主要原因。小脑是中风的常见目标，小脑浦肯野细胞是最易受缺血性损伤的脑细胞之一。然而，对于浦肯野细胞如何对缺血作出反应并受到损伤，我们所知相对较少。这种信息的缺乏是有问题的，因为在其他脑区运作的许多缺血机制涉及的分子过程要么不表达，要么在浦肯野细胞中具有不寻常的配置。本研究将利用脑切片模型模拟体外脑缺血，并利用膜片钳记录、共聚焦荧光成像和药物操作等方法研究小脑缺血损伤的机制。模拟缺血诱导浦肯野细胞严重去极化，这是由非nmda嗜离子性谷氨酸受体（可能还有其他谷氨酸受体/转运体）的激活介导的，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以及随后的坏死和凋亡细胞死亡的发展有关，这与在体内模型中观察到的非常相似。模拟缺血还会严重破坏小脑的电信号传导，这种破坏在缺血发作结束后仍会持续很长时间。确定细胞损伤和信号处理中断的机制将为治疗的发展提供有用的信息。本研究的具体目的是：1)确定浦肯野细胞周围谷氨酸积累的机制，阐明哪些受体介导浦肯野细胞反应并确定其对细胞损伤的贡献；2)确定GABAA受体激活延迟浦肯野细胞去极化发生的机制，并确定这种延迟是有益的还是有害的；3)确定在小脑回路中电信号转导被破坏的位置和机制。

DESCRIPTION (provided by applicant): ' 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.