亚低温对大鼠全脑缺血再灌注损伤后海马CA1区c-Jun蛋白表达的影响

目的研究亚低温对大鼠全脑缺血再灌注损伤后海马CA1区神经元的保护作用,并探讨其可能的机制。方法采用四血管阻断法建立大鼠全脑缺血模型。SD大鼠,随机分为假手术组(SH组)、常温组(IR组)和亚低温组(HIR组)。各组在全脑缺血15min后分别再灌注6h、12h、1d、3d,采用苏木素-伊红(HE)染色观察各时间点海马CA1区细胞形态学变化和TUNEL法检测海马CA1区神经元凋亡,免疫印迹检测c-Jun蛋白表达。结果(1)HE染色结果 IR组和HIR组于全脑缺血再灌注后6h,HE染色未见明显改变,IR组缺血再灌注1d时CA1区出现严重改变,3d时损伤最严重,出现细胞数目减少,细胞胞体缩小、胞核固缩深染,损伤严重,排列紊乱,核膜不清,核仁消失。而HIR组海马存活的锥体细胞数较之IR组12h、1d、3d时间点均明显增加(P<0.05)。(2)TUNEL标记IR组于缺血再灌注后6h在海马CA1区阳性细胞开始增多,缺血再灌注1 d时阳性细胞数最多。而HIR组各时间点阳性细胞数均较IR组明显减少(P<0.01)。(3)免疫印迹结果全脑缺血再灌注后6h c-Jun蛋白在IR组海马CA1区表达开始增加,12h达高峰,持续到3d;HIR组在各时间点的表达均弱于IR组(P<0.01)。结论亚低温通过减少海马CA1区c-Jun的表达,抑制海马CA1区神经元的凋亡,可能是亚低温脑保护作用的机制之一。

Mild hypothermia affects c-Jun expression in hippocampal CA1 subfield following globle cerebral ischemia

Objective To investigate the neuroprotection of mild hypothermia on the hippocampal CA1 neurons following global cerebral ischemia/ reperfusion in SD rat models,and to explore the possible underlying mechanism.Methods Global cerebral ischemia/reperfusion model was produced by 4-VO method.Rats were randomly divided into 3 groups:sham(SH)group,normothermic ischemic reperfusion(IR)group and hypothermic ischemic reperfusion(HIR)group.15min after the cerebral ischemia,the reperfusion was performed for 6h,12h,1d and 3d.The changes of hippocampal neurons morphology in the CA1 subfield were observed by hematoxylin-eosin(HE)staining and the neuron apoptosis was detected by TUNEL method.The c-Jun expression was detected by immuno-blotting test at each time point.Results Neurons in hippocampal CA1 subfield of IR group were observed abnormal appearance by HE staining with pyknotic nucleus,shrunken shape and destroyed-former lines on 1d after ischemia/reperfusion,especially on 3d after ischemia/reperfusion.Compared with IR group,the number of normal cells increased in hippocampal CA1 subfield of HIR group at 12h,1d and 3d(P<0.05).Compared with SH group,markedly TUNEL positive cell increased in hippocampal CA1 subfield of IR group at 6h,especially on 1d(P<0.01).The number of apoptotic cells in hippocampal CA1 subfield of HIR group were less than that of IR group at corresponding time(P<0.01).In CA1 subfield of IR group after global cerebral ischemia/ reperfusion,c-Jun peaked at 12h and continued until 3d,and the espression of c-Jun significantly decreased in hippocampal CA1 subfield of HIR group at corresponding time(P<0.01).Conclusion Mild hypothermia decreases number of apoptotic cells in hippocampal CA1 subfield by inhibiting the overexpression of c-Jun and protect neurons.