无创性延迟肢体缺血预适应促进mitoKATP开放减轻大鼠脑缺血/再灌注损伤

Noninvasive delayed limb ischemic preconditioning alleviates cerebral I/R injury in rats by promotingmitoKATP opening

目的:探讨无创性延迟肢体缺血预适应(noninvasive delayed limb ischemic preconditioning, NDLIP)促进线粒体ATP敏感性钾通道(mitoK_(ATP))开放,发挥脑缺血/再灌注(I/R)损伤神经保护作用的相关机制。方法:健康雄性Wistar大鼠随机分为Sham组、I/R组、NDLIP组和NDLIP+5-HD组,每组12只。缺血1 h/再灌注24 h后进行神经行为评分,TTC染色法测量脑梗死面积。提取缺血皮层线粒体,检测线粒体膜电位和呼吸链复合体Ⅰ、Ⅱ及Ⅳ的活性。Western blot法检测缺血大脑皮层中Bax、Bcl-2和Caspase 3蛋白的表达。结果:与I/R组相比,NDLIP组神经行为评分明显降低,脑梗死面积明显缩小,NDLIP可对抗脑缺血I/R损伤,发挥神经保护作用。NDLIP组缺血皮层线粒体膜电位的降低幅度较小,线粒体复合体活性明显提高,Bax/Bcl-2比值与Caspase 3蛋白的表达均显著降低,NDLIP可改善I/R后脑组织线粒体功能,抑制I/R后线粒体相关凋亡通路。mitoK_(ATP)抑制剂5-HD可减弱甚至抵消以上保护作用。结论:NDLIP可能通过促进mitoK_(ATP)开放而减轻大鼠脑I/R损伤。

OBJECTIVE To investigate whether noninvasive delayed limb ischemic preconditioning(NDLIP)exerts neuroprotective effects on cerebral ischemia/reperfusion(I/R)injury by promoting the opening of mitochondrial ATP-sensitive potassium channels(mitoK_(ATP)).METHODS Healthy male Wistar rats were randomly divided into Sham group, I/R group, NDLIP group and NDLIP+5-HD group, with 12 rats in each group.Neurobehavioral scoring was performed 24 hours after reperfusion, and the size of cerebral infarction was measured by TTC staining.Mitochondria were extracted from ischemic cortex to detect mitochondrial membrane potential and the activities of respiratory chain complexes Ⅰ,Ⅱ and Ⅳ.The expressions of Bax, Bcl-2 and Caspase 3 proteins in ischemic cerebral cortex were detected by Western blot.RESULTS Compared with the I/R group, the neurobehavioral score and the cerebral infarction area of the NDLIP group were significantly reduced.NDLIP could protect against cerebral ischemia I/R injury and exert neuroprotective effects.The reduction of mitochondrial membrane potential in the ischemic cortex of NDLIP group was smaller, the activity of mitochondrial complex was significantly increased, and the ratio of Bax/Bcl-2 and the expression of Caspase 3 protein were significantly decreased.NDLIP could improve the mitochondrial function of brain tissue after I/R,inhibit mitochondrial-related apoptosis pathway after I/R.The mitoK_(ATP) inhibitor 5-HD can attenuate or even offset the above protective effects.CONCLUSION NDLIP may attenuate cerebral ischemia-reperfusion injury in rats by promoting mitoK_(ATP) opening.