MOLECULAR MECHANISMS ISCHEMIA REPERFUSION BRAIN INJURY

这个正在进行的项目的总体目标是更全面地了解线粒体功能障碍和氧化分子改变在缺血/再灌注脑损伤中的作用。具体目的是为了扩大在过去几年中得出的最重要的结论，并通过结合临床相关的动物模型（短暂性全身缺血）、神经元和星形胶质细胞培养模型（缺氧和兴奋性毒性延迟细胞死亡）和线粒体应激亚细胞模型来检验以下假设。1. 脑线粒体释放凋亡因子细胞色素c，以响应升高的Ca2+，氧化应激和特定细胞死亡蛋白的存在，通过膜通透性过渡独立和依赖的机制，可以由独特的神经保护剂控制。2. 线粒体蛋白和脂质的氧化改变是细胞内Ca2+、活性氧和代谢紊乱在急性缺血和再灌注期间引起线粒体功能改变的共同途径。3. 丙酮酸脱氢酶的早期再灌注依赖性丧失是选择性神经元对氧化应激和延迟细胞死亡的敏感标志。4. 延迟、缺血后高压氧治疗通过增加线粒体和其他细胞区室中抗氧化防御机制的表达，减少选择性易损神经元的氧化损伤和死亡。这些研究的意义在于，它们将明确脑缺血再灌注时线粒体损伤的分子机制，它们将阐明线粒体功能障碍促进神经细胞死亡的模式，它们将有助于确定神经保护的新靶点，它们将进一步测试缺血前和缺血后高压氧治疗的神经保护潜力。

The overall goal of this ongoing project is to gain a more complete understanding of the roles that mitochondrial dysfunction and oxidative molecular alterations play in ischemia/reperfusion brain injury. The specific aims are designed to amplify the most important conclusions made during the last few years and to test the following hypotheses using a combination of a clinically relevant animal model of transient global ischemia, neuronal and astrocytic cell culture models of hypoxic and excitotoxic delayed cell death, and subcellular models of mitochondrial stress. 1. Brain mitochondria release the apoptosis factor cytochrome c in response to elevated Ca2+, oxidative stress, and the presence of specific cell death proteins by membrane permeability transition independent and dependent mechanisms that can be controlled by unique neuroprotective agents. 2. Oxidative alterations to mitochondrial proteins and lipids is a common pathway by which elevated intracellular Ca2+, reactive oxygen species and metabolic derangements cause mitochondrial functional alterations during both acute ischemia and during reperfusion. 3. Early reperfusion-dependent loss of pyruvate dehydrogenase is a sensitive marker of selective neuronal vulnerability to oxidative stress and delayed cell death. 4. Delayed, post-ischemic hyperbaric oxygen therapy reduces oxidative injury and death in selectively vulnerable neurons through increasing expression of antioxidant defense mechanisms present in mitochondria and in other cellular compartments. The significance of these studies is that they will define the molecular mechanisms by which mitochondria are injured during cerebral ischemia and reperfusion, they will explicate the modes by which mitochondrial dysfunction promotes neural cell death, they will help identify novel targets for neuroprotection, and they will further test the neuroprotective potential of both pre- and postischemic hyperbaric oxygen therapy.