Cerebral Arteriole Function during Hyperglycemic Stroke

描述（由申请人提供）：缺血性中风是最常见的病理生理事件之一，每年在美国影响超过75万人。约20%的脑卒中患者存在先前存在的高血糖，与脑缺血后再灌注损伤增强相关，包括脑梗死和水肿形成的发生率和严重程度显着增加。虽然大多数研究都集中在高血糖卒中期间的代谢紊乱或神经元组织损伤，但我们的初步数据表明，葡萄糖对血管系统有直接影响，导致缺血和再灌注（I/R）期间灌注不良和血管损伤增加。我们的初步数据还表明，高血糖会上调血管壁内的信号分子，包括蛋白激酶C （PKC）和活性氧（ROS），我们假设它们会影响血管功能（张力、通透性），从而减少再灌注，增强I/R期间的血管源性水肿。此外，高血糖卒中期间产生的增强缺血导致再灌注损伤增强，进一步损害血管系统。该建议的重点是了解1)卒中前血糖升高如何以影响缺血后再灌注和卒中结局的方式影响脑血管功能，以及2)高血糖如何与I/R结合，增加血管损伤。在正常血糖和高血糖状态下，采用大鼠大脑中动脉闭塞模型诱导可控I/R，然后从脑组织中剥离穿透性脑内小动脉，在体外加压动脉造影系统中进行研究，该系统可以控制血管内压力，测量管腔直径，并用荧光和电子密度示踪剂灌注以测定通透性。本提案的目的1将研究葡萄糖诱导的PKC激活和ROS产生在卒中前介导小动脉功能变化中的作用，以及这些变化如何影响卒中预后。目的2将确定卒中期间高血糖如何影响血管完整性，包括血管平滑肌和内皮细胞损伤。这些研究首次专门研究了I/R和高血糖对穿透性脑小动脉的直接影响，这些小动脉与脑中的其他细胞类型密切相关，包括星形胶质细胞、周细胞和神经元，这些细胞已知与脉管系统有显著的相互作用，可以影响灌注、通透性和卒中结局。

DESCRIPTION (provided by applicant): Ischemic stroke is one of the most common pathophysiologic events affecting more than 750,000 people per year in the US. Preexisting hyperglycemia, present in ~20% of all stroke patients, is associated with enhanced reperfusion injury in the postischemic brain, including a significantly higher incidence and severity of cerebral infarction and edema formation. While most studies have focused on metabolic derangements or neuronal tissue damage during hyperglycemic stroke, our preliminary data demonstrate that there is a direct effect of glucose on the vasculature that leads to poor perfusion and increased vascular damage during ischemia and reperfusion (I/R). Our preliminary data also demonstrate that hyperglycemia upregulates signaling molecules within the vascular wall, including protein kinase C (PKC) and reactive oxygen species (ROS) that we have hypothesized has an effect on vascular function (tone, permeability) to decrease reperfusion and enhance vasogenic edema during I/R. In addition, augmented ischemia created during hyperglycemic stroke leads to enhanced reperfusion injury that further damages the vasculature. This proposal is focused on understanding 1) how elevated glucose prior to stroke affects cerebrovascular function in a way that influences postischemic reperfusion and stroke outcome, and 2) how hyperglycemia, in combination with I/R, augments vascular damage. The middle cerebral artery occlusion model in rats will be used under normoglycemic and hyperglycemic conditions to induce controlled I/R, after which penetrating brain parenchymal arterioles will be dissected from the brain tissue and studied in vitro in a pressurized arteriograph system that allows for control over intravascular pressure, measurement of lumen diameter, and perfusion with fluorescent and electron dense tracers for determination of permeability. Aim 1 of this proposal will investigate the role of glucose-induced PKC activation and ROS production in mediating changes in arteriole function prior to stroke and how those changes influence stroke outcome. Aim 2 will determine how hyperglycemia during stroke affects vascular integrity, including vascular smooth muscle and endothelial cell damage. The proposed studies are the first to specifically investigate the direct effect of I/R and hyperglycemia on small penetrating brain arterioles that are in close association with other cell types in the brain, including astrocytes, pericytes and neurons that are known to have significant interaction with the vasculature and can influence perfusion, permeability, and stroke outcome.