Endothelial Preconditioning and Ischemic Brain Injury

描述（由申请人提供）：缺血预处理（IPC）已被证明是减少中风动物模型缺血性脑损伤的最有效方法之一。 注意力集中在神经元可能受到这种预处理保护的机制上。 然而，我们已经发现IPC也保护形成血脑屏障的内皮免受缺血性损伤。 “缺血”预处理也保护体外脑内皮细胞免受氧葡萄糖剥夺诱导的损伤，表明可以对内皮进行直接预处理。 脑内皮损伤可能以多种方式增强缺血性脑损伤，并且考虑到内皮损伤（出血性转化）在限制使用组织纤溶酶原激活剂治疗缺血性卒中中的作用，确定减少内皮损伤的机制尤其相关。 我们将在体内（大鼠大脑中动脉闭塞）和体外（大鼠脑微血管内皮细胞的原代培养）研究脑内皮预处理的机制。 体外实验将有助于探索预处理的机制，同时确保预处理直接作用于内皮。 体内实验将确保体外阐明的机制也发生在整个动物中，并允许评估预处理对其他参数（如血流量、毛细血管形态和梗死）的影响。 总的来说，该提案有三个主要目标。 1)确定预处理的时间进程及其对内皮的影响程度（具体目标1）。 2)确定可触发内皮预处理的事件（具体目标2）。 3)确定触发什么机制来保护内皮（具体目标3）。 这些实验应提供以下信息：A）保护脑内皮免受缺血性损伤的内源性防御机制，可能是治疗靶点。 B）内皮预处理在IPC对脑的影响中的作用。 C）内皮损伤在缺血对脑的总体影响中的作用。

DESCRIPTION (provided by applicant): Ischemic preconditioning (IPC) has proved to be one of the most effective methods of reducing ischemic brain damage in animal models of stroke. Attention has focused on the mechanisms by which neurons may be protected by such preconditioning. However, we have found that IPC also protects the endothelium, which forms the blood-brain barrier, from ischemic damage. 'Ischemic' preconditioning also protects cerebral endothelial cells in vitro from oxygen glucose deprivation induced injury indicating that there can be direct preconditioning of the endothelium. Damage to the cerebral endothelium may potentiate ischemic brain injury in a number of ways and determining mechanisms to reduce endothelial damage is particularly pertinent at the moment considering the role of endothelial injury (hemorrhagic transformation) in limiting the use of tissue plasminogen activator for the treatment of ischemic stroke. We will examine the mechanisms involved in cerebral endothelial preconditioning both in vivo (rat middle cerebral artery occlusion) and in vitro (primary cultures of rat cerebral microvessel endothelial cells). The in vitro experiments will facilitate exploration of the mechanisms involved in preconditioning while assuring that the preconditioning acts directly on the endothelium. The in vivo experiments will ensure that the mechanisms elucidated in vitro also occur in the whole animal as well as allowing an assessment of the effects of preconditioning on other parameters (such as blood flow, capillary morphology and infarction). Overall the proposal has three main goals. 1) Determine the time course of preconditioning and the extent of its effects on the endothelium (Specific Aim 1). 2) Determine the events that can trigger endothelial preconditioning (Specific Aim 2). 3) Determine what mechanisms are triggered to protect the endothelium (Specific Aim 3). These experiments should provide information on: A) Endogenous defense mechanisms that protect the cerebral endothelium from ischemic injury and which may be therapeutic targets. B) The role of endothelial preconditioning in the effects of IPC on the brain. C) The role of endothelial injury in the overall effects of ischemia on the brain.