预适应与后适应联合干预对脑缺血/再灌注损伤的保护作用

Combined intervention of preconditioning and postconditioning against cerebral ischemia/reperfusion injury

目的:探讨缺血预适应联合缺血后适应对大鼠脑缺血/再灌注(I/R)损伤的保护作用及可能的机制。方法:60只SD大鼠随机均分为假手术组,脑I/R组(模型组),脑I/R+预适应(预适应组),脑I/R+后适应组(后适应组),脑I/R+预适应与后适应联合干预组(联合干预组)。采用线栓法制作大鼠脑I/R损伤模型,预适应在造模24 h和1 h前采用3个循环的大脑中动脉阻闭15 s/再通30 s的方法诱导,后适应于再灌注前采用3个循环的再灌注30 s/缺血15 s的方法诱导。造模后48 h,分别检测大鼠脑梗死体积,脑组织氧化应激指标及p-Akt与p-ERK1/2蛋白的表达。结果:预适应组与后适应组间脑梗死灶体积比较差异无统计学意义(P>0.05),但均明显小于模型组,大于联合干预组(均P<0.01)。与假手术组比较,模型组出现脑组织氧化应激水平明显升高(SOD活性降低,MDA含量升高),且脑组织p-Akt和p-ERK1/2表达上调(均P<0.01)。与模型组比较,预适应组脑组织氧化应激指标无明显差异(均P>0.05),但p-Akt表达轻度上调、p-ERK1/2表达明显上调(P<0.05,P<0.01),后适应组脑组织氧化应激水平明显降低(均P<0.01),且p-Akt表达明显上调和p-ERK1/2表达轻度上调(P<0.01,P<0.05)。联合干预组脑组织氧化应激水平降低程度及p-Akt与p-ERK1/2表达上调程度均明显强于预适应组或后适应组(均P<0.01)。结论:预适应与后适应联合干预对脑缺I/R损伤的保护作用强于单独的预适应或后适应,可能与预适应与后适应的抗I/R损伤的机制不同且互补有关。

Objective:To investigate the protective effect of combined ischemic preconditioning and postconditioning against cerebral ischemia/reperfusion(I/R) injury and the potential mechanism.Methods:Sixty SD rats were randomized into a sham operation group,a brain I/R group(model group),a brain I/R plus preconditioning group(preconditioning group),a brain I/R plus postconditioning group(postconditioning group),and a brain I/R plus preconditioning and postconditioning group(combined intervention group).The rat brain I/R injury model was created by suture emboli method.Preconditioning was induced by 3 cycles of 15 s occlusion followed by 30 s recanalization of the middle cerebral artery twice respectively at 24 h and 1 h before model creation,and postconditioning was elicited by 3 cycles of 30 s reperfusion followed by 15 s ischemia before long time reperfusion.The rats were sacrificed at 48 h after the reperfusion.The cerebral infarct volume and oxidative stress parameters as well as p-Akt and p-ERK1/2 protein expressions in the brain tissues were determined.Results:The cerebral infarct volumes showed no significant difference between the preconditioning group and the postconditioning group(P>0.05),but both were smaller than that in the model group and larger than that in the combined intervention group(all P values<0.01).In the model group,the level of oxidative stress was markedly increased(SOD activity increased and MDA level decreased),and both p-Akt and p-ERK1/2 protein expressions in the brain tissues were upregulated compared with those in the sham group(all P<0.01).Compared with the model group,the oxidative stress parameters presented no evident difference in preconditioning group(P>0.05),but p-Akt expression was slightly upregulated and p-ERK1/2 was remarkably down-regulated(P<0.05 and P<0.01) In the postconditioning group,the level of oxidative stress was significantly decreased,and p-Akt expression was dramatically increased with a mild down-regulation of p-ERK1/2 expression(P<0.01 and P<0.05).In the combined intervention group,the oxidative stress decrease the p-Akt expression rise and p-ERK1/2 expression inhibition were significantly greater than those in either the preconditioning group or the postconditioning group(all P values<0.01).Conclusion:Combined treatment of preconditioning and postconditioning exerts stronger protective effect against cerebral I/R injury than either preconditioning or postconditioning alone.The mechanism is possibly due to the different but complementary protection of preconditioning and postconditioning against I/R injury.