后适应对大鼠脑缺血-再灌注损伤线粒体结构和功能的影响

目的观察后适应对大鼠脑缺血-再灌注损伤线粒体结构和功能的影响。方法雄性SD大鼠随机分为假手术组、缺血-再灌注模型组(MCAO)、MCAO 预适应组、MCAO 后适应组和MCAO 尼莫地平组。大鼠脑缺血-再灌注24 h后,取脑进行TUNEL染色,免疫组织化学检察Bcl-2,Bax,Casepase-3和p53的蛋白表达,测定大鼠脑组织线粒体肿胀度、膜流动性、膜磷脂(PL)和丙二醛(MDA)含量、测定线粒体Na -K -ATP酶、Ca2 -ATP酶和超氧化物歧化酶(SOD)活性,并观察线粒体超微结构的改变。结果脑缺血-再灌注后半暗带线粒体的MDA含量明显增高,PL含量减少,膜脂流动性降低;ATP含量及Na -K -ATP酶、Ca2 -ATP酶、SOD活性明显降低。与MCAO组比较,后适应组大鼠凋亡细胞和Bax、Casepase-3、p53蛋白表达明显减少,ATP含量及Na -K -ATP酶、Ca2 -ATP酶、SOD活性明显升高。MCAO组大鼠脑线粒体肿胀,线粒体嵴断裂、溶解和消失,后适应明显减少缺血-再灌注引起的线粒体损伤程度。结论后适应对MCAO大鼠脑和线粒体的保护作用可能与其减少神经原凋亡,抑制p53、Bax、casepase-3表达,增加线粒体Na -K -ATPase、Ca2 -ATPase、SOD活性有关。

Effect of postconditioning on mitochondria structure and function in cerebral ischemia reperfusion rats

Objective To investigate the effect of postconditioning on the structure and function of mitochondria in local cerebral ischemia-reperfusion rats.Methods Male Sprague-Dawley rats were randomized into 5 groups(n=10):sham-operated group,MCAO group,Preconditioning MCAO group,postconditioning MCAO group and nimodipine MCAO group.At the 24 h after the reperfusion,the brains were obtained for TUNEL staining,and bcl-2,Bax,and Casepase-3 expression were detected by immunohistochemistry method.Cortex mitochondria were isolated and prepared for the measurement of membrane fluidity and swelling.The activities of mitochondrial Na -K -ATPase,Ca2 -ATPase,and superoxide dismutase(SOD),and contents of ATP,phospholipid,and malondial dehyde(MDA)were determined.Morphological changes of neuronal mitochondria were observed by electronic microscope.Results The content of mitochondria MDA was markedly increased,and the activities of Na -K -ATPase,Ca2 -ATPase and SOD in the mitochondria were decreased significantly in the MCAO group.In the postconditioning groups,the apoptotic cells and the protein expression of Bax and Casepase3 were significantly decreased(P<0.01),the activity of Na -K -ATPase,Ca2 -ATPase,and SOD in the mitochondria were enhanced,and the contents of MDA in the mitochondria was decreased.The mitochondria swelled,and the cristae was disrupted,dissolved or disappeared in the MCAO rats.Postconditioning reduced these changes induced by cerebral ischemia in rats.Conclusion The mechanism of brain protection and alleviation of mitochondria damage with postconditioning may be related to decreasing the apoptosis of neural cells,inhibiting the expression of Bax and casepase-3,and increasing the activities of Na -K -ATPase,Ca2 -ATPase,and SOD of mitochondria in the MCAO rats.