缺血后处理对糖尿病大鼠局灶性脑缺血再灌注损伤线粒体的影响

目的观察缺血后处理(I-Post)对糖尿病大鼠局灶性脑缺血再灌注损伤线粒体超微结构和功能的影响,探讨I-Post诱导的脑保护的可能机制。方法采用链脲佐菌(STZ)腹腔注射建立糖尿病大鼠模型,在此基础上通过线栓法建立大鼠大脑中动脉阻塞/再灌注模型。SD糖尿病大鼠随机分为4组(n=10),空白对照组、假手术组、缺血再灌注组(I/R组)、缺血后处理组(I-Post组)。于缺血90min再灌注6h后电镜下观察线粒体超微结构、测定缺血侧脑组织线粒体中超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)、丙二醛(MDA)、Na+/K+-ATPase和Ca2+-ATPase活性。结果缺血后处理能明显减轻I/R引起的线粒体超微结构的损伤,提高线粒体SOD、GSH-Px、Na+/K+-ATPase和Ca2+-ATPase的活性(P<0.05或0.0),降低MDA的含量(P<0.05)。结论线粒体可能在I-Post诱导的脑保护中起关键性作用,I-Post诱导的脑保护机制可能与SOD、Na+/K+-ATP酶、Ca2+-ATP酶和GSH-Px活性增加有关。

Role of mitochondria in ischemic postconditioning-induced attenuation of cerebral ischemia in diabetic rats

Objective To investigate the effect of ischemic postconditioning(I-Post) on mitochondria after focal cerebral ischemia-reperfusion in streptozotocin-induced diabetic rats.Methods The rats were made diabetic by a single intraperitoneal injection of streptozotocin.Focal ischemia was generated by transient middle cerebral artery occlusion(MCAO).Diabetic rats were randomly assigned to four groups(n=10):1) control group;2) Sham-operated group;3) I/R group;4) I-Post group:the brain was subjected to middle cerebral artery occlusion for 90 min,then treated for 15 sec,15 sec,15 sec by brief reperfusion consecutively,each was separated with occlusion for 15 sec,followed by a persistent reperfusion,which made the total reperfusion time the same as the other three groups.The ultrastructure of mitochondria was observed by electron microscope 6 h later.The level of malondialdehyde (MDA),Na+,K+-ATPase,Ca2+-ATPase,Superoxide dismutase (SOD) and glutathione peroxidase(GSH-Px) in mitochondria were measured 6 h later,according to the commercial kit manual.Results Plasma glucose in diabetic rats was routinely 24.6±3.5mmol/L.The changes ultrastructure of mitochondria in cortex were significantly decreased in I-post group compared with I/R group.The content of MDA in mitochondria was markedly decreased and the activities of Na+,K+-ATPase,Ca2+-ATPase,SOD and GSH-Px in mitochondria were increased in I-post group compared with the I/R group group ( P<0.05 or P<0.01).Conclusion Mitochondria may play a central role in I-Post cerebroprotection,increase of the activities of SOD、Na+/K+-ATPase、Ca2+-ATPase and GSH-Px plays a important role in the mechanism of protection on brain and mitochondria damage in diabetic rats by I-Post.