Neuroprotection by Allopregnanolone through Modulation of GABAA Receptors

描述（由申请人提供）：在中风或心脏骤停期间经历的全局性脑缺血仍然是美国的主要杀手，那些在急性发作中幸存下来的人会经历许多神经功能障碍。目前，还没有治疗方法可以防止心脏骤停或中风造成的神经损伤。开发有效治疗方法的主要障碍之一是缺乏对神经元在缺氧时死亡的方式和原因的理解。兴奋性毒性，即CMS中谷氨酸的过度释放，是缺血时发生的一种病理生理事件，被认为是细胞死亡的主要原因。然而，使用谷氨酸受体拮抗剂来阻断兴奋性毒性的治疗在人类中会导致许多有害的副作用。或者，增加抑制性张力的水平可以防止兴奋性毒性。使用GABA受体激动剂阻断兴奋性毒性的研究产生了不一致的结果，导致对GABA激活化合物作为治疗剂的兴趣丧失。最近的研究揭示了对这些发现的一种可能的解释，这些研究表明GABAA受体蛋白在缺血后减少，可能降低了GABA增强药物的有效性。我们的实验室已经能够在培养的浦肯野细胞中重申这些发现，浦肯野细胞接受强大的兴奋和抑制驱动，特别容易缺血。利用电生理记录来评估GABAA受体的功能活性，结合分子生物学和组织学技术，我计划表征缺血后GABAA受体活性的功能下降，并确定神经类固醇异孕酮对神经保护的机制。

DESCRIPTION (provided by applicant): Global cerebral ischemia, as experienced during stroke or cardiac arrest, continues to be a major killer in the US and those who survive the acute attack experience many neurological deficits. Currently, there are no therapies to prevent neurological damage from cardiac arrest or stroke. One of the major obstacles for developing effective treatments is the lack of understanding how and why neurons die when deprived of oxygen. Excitotoxicity, excessive release of glutamate in the CMS, is a pathophysiological event that occurs during ischemia and is thought to be a major culprit in cell death. However, therapies using glutamate receptor antagonists to block excitotoxicity result in many detrimental side effects in humans. Alternatively, increasing the level of inhibitory tone may prevent excitotoxicity. Studies using GABA receptor agonists to block excitotoxicity have yielded inconsistent results, resulting in a loss of interest in GABA activating compounds as therapeutic agents. A possible explanation for these findings was unveiled in more recent studies which show that GABAA receptor protein is decreased following ischemia, possibly decreasing the effectiveness of GABA potentiating drugs. Our lab has been able to reaffirm these findings in Purkinje cells in culture, which receive robust excitatory and inhibitory drive and are particularly susceptible to ischemia. Using electrophysiological recordings to asses the functional activity of GABAA receptors, coupled with molecular biology and histology techniques, I plan to characterize the functional decline in GABAA receptor activity following ischemia and determine the mechanism of neuroprotection granted by the neurosteroid allopregnanolone.