远隔缺血预适应对大鼠局灶性脑缺血后诱导型一氧化氮合酶的影响

Effect of remote ischemic preconditioning on inducible nitric oxide synthase expression following focal cerebral ischemia in rat

目的研究远隔缺血预适应(remote ischemic preconditioning,RIPC)对大鼠脑缺血再灌注后诱导型一氧化氮合酶(inducible nitric oxide synthase,iNOS)表达的影响,以探讨RIPC保护脑缺血损伤的相关机制。方法应用线栓法制作大脑中动脉栓塞(middle cerebral artery occlusion,MCAO)模型,将21只健康雄性SD大鼠采用数字表法随机分为3组:假手术组(sham,n=7),MCAO组(n=7),RIPC+MCAO组(n=7)。在MCAO手术前连续3 d,进行远隔肢体缺血预适应处理(双侧股动脉夹闭10 min/放开10 min,每天3次)。在缺血2 h-再灌注24 h后进行神经功能评分,TTC染色检测脑梗死体积,采用Western blotting方法检测梗死侧脑组织的iNOS蛋白表达水平。结果 1)在MCAO手术过程中,3组实验动物的生理指标均在正常范围内,且组间差异无统计学意义。与sham组相比,MCAO组大鼠再灌注24 h时神经功能缺损评分显著升高、脑梗死体积明显增大(P<0.05)。而RIPC+MCAO组大鼠神经功能较MCAO组大鼠得到明显改善、脑梗死体积显著减少(P<0.05)。2)再灌注24 h时,与sham组相比,MCAO组大鼠脑梗死侧iNOS蛋白表达显著增加(P<0.05)。与MCAO组相比,RIPC+MCAO组大鼠脑梗死侧iNOS蛋白表达显著降低(P<0.05)。结论 RIPC处理对大鼠脑缺血损伤具有保护作用,其机制与降低脑缺血大鼠脑内iNOS蛋白表达有关。

Objective The objective of this study is to investigate the effect of remote ischemic preconditioning（ RIPC） on the expression of inducible nitric oxide synthase（iNOS） in ischemia-reperfusion rats to explore the relative mechanisms of RIPC on cerebral ischemic injury. Methods Middle cerebral artery occlusion（MCAO） operation was performed using suture method. Twenty-one male Sprague Dawley rats were divided randomly into three groups： sham group（n=7）, MCAO group（n=7） and RIPC＋MCAO group（n=7）. Three cycles of RIPC induced by temporarily occluding the bilateral femoral arteries（10 minutes） prior to 10 minutes of reperfusion were given three times a day for 3 days before the animal received MCAO surgery. After 2 h ischemia and 24 h reperfusion, neurological deficits were evaluated and brain infarct volume was measured by 2, 3, 5-triphenyltetrazolium chloride（TTC） staining. The expression of iNOS in ipsilateral hemisphere was determined quantitatively by Western blotting analysis. Results ① The physiological parameters of the three groups of rats were in normal arrange showing no statistically significant difference. The neurological deficit score and brain infarct volume in MCAO group rats increased significantly compared with those of sham group at 24 h after reperfusion（P〈0. 05）, which were significantly decreased by RIPC＋MCAO treatment（P〈0. 05）. ② The expression of iNOS in ipsilateral hemispheres of MCAO group rats at 24 h after reperfusion increased significantly compared with that of sham group rats（P〈0. 05） while the expression of iNOS in RIPC＋MACAO group reduced remarkably compared with that of MCAO group（ P 〈 0. 05）. Conclusion RIPC treatment protects against cerebral ischemic injury in rats, which might be related to the decreased expression of iNOS in the ischemic brain.