亚低温对脑缺血再灌注损伤的保护作用机制

Protective mechanism of mild hypothermia on cerebral ischemia-reperfusion injury

目的探索亚低温对脑缺血再灌注(I/R)损伤的保护作用机制。方法将36只雄性SD大鼠随机分为假手术组、重组组织型纤溶酶原激活剂(rt-PA)组、模型组、I/R+亚低温组、I/R+rt-PA组、I/R+亚低温+rt-PA组,每组各6只。通过构建大鼠的缺血再灌注模型,进行神经功能半定量缺损评分;大鼠血脑屏障渗透实验,比较各组血脑屏障保护作用的差异;免疫组化检测大鼠脑组织中t-PA和组织型纤溶酶原激活物抑制剂(PAI-1)的表达;Western blot检测p-MEK1/2和p-ERK1/2的表达。结果两个亚低温处理大鼠模型组神经损伤情况均低于模型组(P<0.05);亚低温治疗可以降低血脑屏障的通透性;rt-PA组和I/R+rt-PA组大鼠脑组织中t-PA和PAI-1的表达量明显增加,其余各组表达量均较低;rt-PA组和I/R+rt-PA组的p-MEK1/2和p-ERK1/2表达量显著增加,而亚低温处理后可明显降低p-MEK1/2和p-ERK1/2表达量。结论亚低温对脑缺血再灌注损伤的保护作用与降低血脑屏障的通透性、降低大鼠脑组织缺血再灌注后t-PA和PAI-1的表达以及降低p-MEK1/2和p-ERK1/2含量有关。

Aim To study the protection mechanism of mild hypothermia on cerebral ischemia-reperfusion(I/R)injury.Methods 36 male SD rats were randomly divided into sham operation group,recombinant tissue plasminogen activator(rt-PA)group,model group,I/R+mild hypothermia group,I/R+rt-PA group,and I/R+mild hypothermia+rt-PA group,with 6 rats in each group.By building the rat model of ischemia reperfusion,the semi quantitative neurological deficit score was made.By the experiment of blood brain barrier penetration,the difference of blood-brain barrier protection was compared among every groups.Immunohistochemistry was used to detect the expressive level of t-PA and PAI-1 in the tissues of rats;Western blot was used to test the expressive level of p-MEK1/2 and p-ERK1/2.Results Neural injury was lower in two groups of mild hypothermic rats than that in experimental control group(P<0.05).Mild hypothermic treatment can reduce the permeability of the blood-brain barrier.The expression of t-PA and PAI-1 in rat brain tissue significantly increased in rt-PA group and I/R+rt-PA group,while the expression of other groups was lower.The p-MEK1/2 and p-ERK1/2 expressions were significantly increased in the rt-PA group and the I/R+rt-PA group,which were significantly reduced after mild hypothermic treatment.Conclusion The protective effect of mild hypothermia on cerebral ischemia reperfusion injury is related to reducing the permeability of blood-brain barrier,reducing the expression of t-PA and PAI-1 after ischemia reperfusion in rat brain tissue,and reducing the expression of p-MEK1/2 and p-ERK1/2.