缺血再灌注期实施亚低温与再建血运治疗时间窗的影响

Effect of sub-hypothermia during ischemia reperfusion on time window for restoration of blood flow in rats

目的观察缺血灌注期间实施亚低温对再建血运(再灌注)治疗时间窗的影响并探讨其机制。方法将120只雄性大鼠随机分为假手术组(n=10);大脑中动脉闭塞(middle cerebral artery occlusion,MCAO)24 h组(n=10);常温再灌注组:按缺血再灌注时间点分为MCAO 2、3、4、5、6 h,再灌注24 h,每个时相点10只;亚低温再灌注组:时相点同常温再灌注组,每个时相点10只。MCAO 24 h组大脑中动脉闭塞24 h后直接处死,其余组动物均于再灌注24 h后处死。用TTC染色观察梗死体积,对大鼠模型进行Longa评分,用干-湿质量法测定脑含水量,采用免疫组化法检测大鼠模型的AIF、Cyt C、HSP70、MMP-9、LN的表达。结果与脑梗死的近期结局MCAO 24 h组的梗死体积、Longa评分及AIF、Cyt C、HSP70、脑含水量及MMP-9、LN的表达比较:常温再灌注组MCAO 2～4 h再灌注24 h有统计学差异(P<0.01),MCAO 5～6 h再灌注24 h没有统计学差异(P>0.05);亚低温再灌注组MCAO 2～5 h再灌注24 h各组有统计学差异(P<0.01),MCAO 6 h再灌注24 h没有统计学差异(P>0.05)。亚低温再灌注组各时相点的梗死体积、Longa评分、脑含水量及MMP-9、AIF、Cyt C的表达均显著低于相应常温组,HSP70和LN的表达显著高于常温组(P<0.05,P<0.01)。结论再灌注期间实施亚低温可延长再建血运治疗时间窗,其机制可能与其能抑制半暗带细胞的凋亡和抑制MMP-9的表达从而减轻脑微循环破坏,使微循环承受再灌注能力上升有关。

Objective To observe the effect of sub-hypothermia during ischemia reperfusion on time window for restoration of blood flow and its mechanism.Methods One hundred and twenty male rats were randomly divided into sham-operation group（n=10）,24 h middle cerebral artery occlusion（MCAO） group（n=10）,normal temperature（NT） group（n=50）,and sub-hypothermia reperfusion group（n=50）.Twenty-four hours after reperfusion,the animals were killed.Cerebral infarction volume was observed with TTC staining.A Rat model was established and scored with the Longa scoring system.Water content in brain was measured with the dry-wet weight method.Expressions of AIF,Cyt C,HSP70,MMP-9,and LN were detected by immunohistochemistry.Results The cerebral infarction volume,Longa score,expression levels of AIF,Cyt C,HSP70,MMP-9,and LN,water content in brain were significantly different in 24 h MCAO group from those in 2-4 h MCAO group and in different sub-hypothermia reperfusion groups（P0.01）,but no significant difference was found between 5-6 h MCAO group and 24 h MCAO group,and in 6 h sub-hypothermia reperfusion group after 24 h reperfusion（P0.05）.The cerebral infarction volume,Longa score,and expression levels of MMP-9,AIF,and Cyt C were significantly lower while those of HSP70 and LN were significantly higher in sub-hypothermia reperfusion group than in normal temperature group（P0.05）.Conclusion Sub-hypothermia during reperfusion can prolong the time window for restoration of blood flow by inhibiting cellular apoptosis and MMP-9 expression,which can alleviate injury of microcirculation and increase the tolerance to reperfusion.