糖尿病加重脑缺血损伤机制不明，且无有效治疗措施。前期实验结果显示线粒体是糖尿病加重脑缺血损伤的重要靶标。本研究旨在阐明线粒体膜通透转换孔（mitochondrial permeability transition pore，MPTP）在糖尿病加重脑缺血损伤中的作用以及新型MPTP阻滞剂NIM811对其损伤的保护及机制。本课题采用糖尿病脑缺血大鼠脑组织标本进行电镜、免疫组化染色、蛋白印迹、线粒体膜电位、钙承载能力和呼吸链酶复合物功能测定深入研究线粒体形态、功能及MPTP开放在糖尿病加重脑缺血损伤中的作用；通过与环孢素A和免疫抑制剂FK506的疗效对比，研究NIM811的保护效果，进一步阐明MPTP在介导糖尿病加重脑缺血损伤中的作用；采用细胞培养模拟体内高糖缺氧状态，通过测定Sirt3活性、亲环素D乙酰化，免疫共沉淀和siRNA技术研究NIM811作用的分子机制。本研究为防治脑卒中提供依据。

Hyperglycemia exacerbates brain damage induced by cerebral ischemia.The mechanisms responsible for such detrimental effects of hyperglycemia are fully understood.Mitochondria play a pivotal in mediating cell death after cerebral ischemic stroke.Under ischemic condi-tion,mitochondria form a permeability transition pore (MPTP) that allows releases of several pro-apoptotic proteins and activation of cell death pathways.Our preliminary study showed that hyperglycemia caused mitochondrial cytochrome c release in early reperfusion stage after a transient cerebral ischemia,suggesting hyperglycemia causes early damage to the mitochondria. In addition, MPTP inhibitor cyclo-sporine A (CsA) effectively protected brain from hyperglycemia-exacerbated ischemic damage.However,CsA inhibits both the MPT and neuroinflammation and it does not penetrate the blood-brain barrier.In the proposed study,we will induce transient cerebral ischemia in diabetic and nondiabetic rats, employ electron microscope, immunohistochemistry, western blotting, measurements of mitochondrial membrane potential, calcium loading capacity, respiratory function and activities of mitochondrial electron transport complexes to further study the role of mitochondria in ischemic brain damage;Use a specific MPTP blocker NIM811 to determine the role of MPTP in mediating hyperglycemia-enhanced ischemic brain damage; and Induce in vitro hypoxia model that mimics the in vivo hdiabetic ischemic conditions to delineate the acting mechanisms of NIM81.Cell viability, surtuin 3 activity, cyclophilin D acetylation,co-immunoprecipitation of cyclophilin D and adenine nucleotide tranlocase (ANT) will be studied for this purpose.The incidences of diabetes and cerebral stroke increased signifi-cantly in recent years among Chinese people. Delineating the role of mitochondria in hyperglycemia-enhanced ischemic brain damage will help us to understand the damage mechanisms and to develop new therapeutic drugs for clinical usage.