Adenosine receptor activation in spreading depolarization and ischemic injury

描述（由申请人提供）： 本研究金提案的总体研究目标是评估腺苷受体在缺血性卒中所致脑损伤中的作用。缺血性卒中后自发发生重复性扩散性去极化（SD）事件，并促进损伤的扩大。SD是一种大规模的细胞去极化波，其扰乱离子稳态并消耗大脑中的能量。在健康组织中，SD之后是电活动减少和血流量增加的间隔，而在具有最小电活动的损伤组织中，SD之后是血流量减少和神经元细胞死亡。这些现象背后的机制还没有得到很好的理解。神经元和血管对SD的反应可能由腺苷受体激活来解释。腺苷是ATP的低能量代谢物，在代谢失衡期间积累。通过激活细胞表面的G蛋白偶联受体，腺苷可以促进神经元沉默（通过A1受体）和血管舒张（通过A2A受体）。腺苷A2A受体参与了中风动物模型的缺血后脑损伤，但其机制尚不清楚，可能与SD有关。在这个提议中，实验被设计来确定腺苷受体激活在正常组织和中风模型中从扩散去极化事件恢复中的作用。目的1将评估腺苷A1和A2A受体的激活后，SD在其他正常的脑组织从小鼠，使用在体外和体内的方法，解析出神经元和血管的影响。目的2将使用缺血性中风的体内小鼠模型来研究腺苷受体可能持续降低神经元活性的机制，并解释脆弱区域血流量的反常下降。主要方法包括脑切片电生理学、体内电生理学、内在光信号、激光散斑对比成像和缺血性病变的组织学评估。这些研究将有助于该研究员在神经系统疾病方面的博士前培训。拟议的实验结果将阐明中风后大脑恢复和损伤的机制，并可能提出新的治疗方法，以防止缺血性损伤的延迟扩展。

DESCRIPTION (provided by applicant): The overall research goal of this fellowship proposal is to evaluate the involvement of adenosine receptors in brain injury resulting from ischemic stroke. Repetitive spreading depolarization (SD) events occur spontaneously after ischemic stroke, and contribute to the expansion of injury. SD is a wave of massive cellular depolarization which disturbs ionic homeostasis and depletes energy in the brain. In healthy tissue, SD is followed by an interval of reduced electrical activity and increased blood flow, whereas in injured tissue with minimal electrical activity, SD is followed by decreased blood flow and neuronal cell death. Mechanisms underlying these phenomena are not well understood. Both neuronal and vascular reactions to SD might be explained by adenosine receptor activation. Adenosine, a low-energy metabolite of ATP, accumulates during periods of metabolic imbalance. By activating G-protein coupled receptors on the surface of cells, adenosine can contribute to neuronal silence (via the A1 receptor) and vasodilation (via the A2A receptor). Adenosine A2A receptors are implicated in post-ischemic brain damage in animal models of stroke, but the mechanism is yet unknown and might be related to SD. In this proposal, experiments are designed to determine the role of adenosine receptor activation in recovery from spreading depolarization events in normal tissue and in a stroke model. Aim 1 will evaluate the activation of adenosine A1 and A2A receptors after SD in otherwise normal brain tissue from mice, using in vitro and in vivo methods to parse out neuronal and vascular effects. Aim 2 will use an in vivo mouse model of ischemic stroke to examine mechanisms by which adenosine receptors may persistently reduce neuronal activity and explain the paradoxical drop in blood flow in vulnerable areas. Major methodologies to be utilized include brain slice electrophysiology, in vivo electrophysiology, intrinsic optical signals, laser speckle contrast imaging, and histological assessment of ischemic lesions. These studies will contribute to the fellow's predoctoral training in neurological disease. The results of the proposed experiments will elucidate mechanisms of recovery and injury in the brain after stroke, and may suggest novel treatments to prevent the delayed expansion of ischemic injury.