亚低温对局灶性脑缺血再灌注大鼠脑皮质神经元凋亡及存活素、脑源性神经营养因子表达的影响

目的观察亚低温干预对局灶性脑缺血再灌注大鼠脑皮质神经元凋亡及存活累(Survivin)、脑源性神经营养因子(BDNF)表达的影响,探讨Survivin、BDNF在亚低温脑保护机制中的作用。方法采用线栓法制备成年雄性SD大鼠大脑中动脉闭塞(MCAO)局灶性脑缺血再灌注改良模型,将90只大鼠随机分为假手术组、常温缺血组和亚低温缺血组,缺血组分别于缺血3h再灌注3h、6h、12h、24h、48h、72h、7d处死,亚低温缺血组于缺血后10min实施全身亚低温持续3h。进行TUNEL染色及免疫组化染色,检测梗死灶周围皮质神经元凋亡数量和Sur-vivin、BDNF的表达水平。结果 (1)亚低温缺血组和常温缺血组于再灌注6h皮质区均出现TUNEL染色阳性细胞,72h达高峰,随后逐渐减少,两组内相邻时间点比较差异均有统计学意义(P<0.05);在相同时间点亚低温缺血组凋亡细胞数明显少于常温缺血组,两组间比较差异有统计学意义(P<0.05)。(2)亚低温缺血组于再灌注3hSurvivin、BDNF表达有所增加,BDNF于24h达高峰,Survivin于48h达高峰,随后表达逐渐降低,但7d时仍高于假手术组,常温缺血组表达趋势与之相似,两组各时间点Survivin、BDNF表达均高于假手术组,差异有统计学意义(P<0.05);除再灌注3h Survivin表达在亚低温缺血组与常温缺血组间无明显差异外,其余各时间点亚低温缺血组Sur-vivin、BDNF表达均高于常温缺血组,差异有统计学意义(P<0.05)。结论亚低温干预可抑制梗死灶周围脑皮质神经细胞凋亡,促进存活素及脑源性神经营养因子的表达,发挥脑保护作用。

Effect of mild hypothermia on neuron apoptosis and survivin and BDNF expression in rat focal cerebral ischemia-reperfusion

Objective To observe the effects of mind hypothermia on neuron apoptosis and the expression of survivin and BDNF after focal cerebral ischemia-reperfusion,and to study the effect of survivin and BDNF on the neuroprotective mechanisms in mild hypothermia.Methods The modified focal cerebral ischemia-reperfusion models of adult male SD rats were established by occlusion of middle cerebral artery.Then ninety model rats were randomly divided into three groups:sham-operated group,normothermia ischemic group and mild hypothermic ischemic group.Cerebral ischemia group was respectively executed at 3h,6h,12h,24h,48h,72h and 7d.Mild hypothermic ischemic group was implemented mild hypothermia of 3h after 10 minutes of cerebral ischemia.The amount of neuron apoptosis after focal ischemia was observed by TUNEL staining.The expressions of survivin and BDNF were measured with immunohistochemical staining.Results The mild hypothermic ischemic group and the normothermia ischemic group at 6h all appeared TUNEL dying positive cells in cortex,at 72h,reached peak and then gradually reduced.Two groups of adjacent time points in comparative differences were significant(P<0.05).At the same time point and the mild hypothermic ischemic group,the apoptotic cells were obviously less than the normothermia ischemic group,with statistically significant differences(P<0.05).The mild hypothermic ischemia reperfusion group at 3h,survivin and BDNF express increased,BDNF at 24h reached peak,survivin at 48h reached peak and then gradually reduced,but were still higher on 7d than sham-operated group,and the normothermia ischemic group showed similar express trend.Two groups of different time points,survivin and BDNF expression were higher on 7d than sham-operated group,and the difference was statistically significant(P<0.05).In addition to 3h reperfusion,survivin expression in the mild hypothermic ischemic group and the normothermia ischemic group showed no obvious difference between groups,and the rest of the different time points of the mild hypothermic ischemic group.Survivin and BDNF express was higher than in the mild hypothermic ischemic group,with statistically significant difference(P<0.05).Conclusion Intervention of mild hypothermia may promote the expression of survivin and BDNF in the cortex surrounding the ischemic focus and results in restraining the neuronal apoptosis.