亚低温对大鼠局灶性脑缺血神经元细胞凋亡及调控基因Bcl-2和Bax表达的影响(英文)

Effects of mild hypothermia on Bcl-2and Bax gene expression in ischemic brain of rats

目的研究不同时程的亚低温治疗对大鼠大脑中动脉闭塞(MCAO)模型的神经元细胞凋亡及Bcl-2,Bax基因表达的影响。方法健康雄性SD大鼠共40只,月龄两三个月。按抽签法随机分为5组,每组8只(n=8),分别为:假手术组(A)、对照组(B)、亚低温0.5h组(C)、亚低温1.0h组(D)、亚低温3.0h组(E)。采用Longa线栓法制作MCAO模型,缺血3.0h后再灌注。缺血后即刻分别进行不同时程(0.5,1.0,3.0h)的亚低温治疗,再灌注后24h断头取脑,连续切片作TUNEL染色及Bcl-2,Bax免疫组化染色。结果凋亡神经元细胞(TUNEL阳性细胞)主要见于梗死灶周围的纹状体及额顶部皮层。Bcl-2及Bax阳性细胞也主要见于梗死灶周围的纹状体及额顶部皮层,与该区凋亡细胞的集中分布相一致。与对照组的Bcl-2细胞阳性率相比,亚低温3.0h组增加犤(23.0±3.8)%,P<0.05)犦;与对照组的Bax细胞阳性率相比,亚低温1.0,3.0h组均降低犤分别为(45.9±4.1)%,(32.4±3.7)%,P<0.05,P<0.01犦;凋亡细胞阳性率与Bcl-2/Bax的比值呈负相关关系(r=-0.9759,P<0.01)。结论亚低温1.0h以上有抑制细胞凋亡作用;Bcl-2/Bax的比值能影响细胞凋亡的发生。

AIM:To in vestigate the effects of mild hypothermia of different durations on neuronal apo ptosis and expressions of Bcl-2and Bax genes in rat models of middle cerebral artery occlusion(MCAO).METHODS:Forty Sprague Dawley rats were divid ed rando mly into 5equal groups,namely sham-operation grou p(group A),normothermic ischemic controls(group B ),30-min mild hypothermia group(group C ),1 -hour mild hypothermia group(group D),and 3-hour mild hypothermia group(g roup E).MCAO models were established by Lon ga' s method,and reperfusion was allowed after 3-hour occlusion.Mild hypothermia for 0.5,1.0and 3.0h ou rs respectively were initiated at the s tart of occlusion,and at the 24th hou r of subsequent reperfusion,the rat bra in were removed and continuously s ectioned for TUNEL staining,Bcl-2and Bax immunohistochemical staining respect ively.RESULTS:Apoptotic neurons(TUNEL-positive)were identified primarily i n the cortex of the frontal and parie tal lobes and peri-infarct striatum,wher e Bcl-2-and Bax-positive cells were a lso spotted,in similar distributio n pattern to that of TUNEL positive cells.Comp ared with the control group,the p er-centage of Bcl-2-positive cells was significantly higher in group E (2 3.0±3.8,P<0.05),while the percentage of Bax-positi ve cells was lowered in both groups D and E (45.9±4.1,P<0.05;32.4±3.7 ,P<0.01,respectively).Inverse correlation was noted betw een the apopto tic rate and the Bcl-2to Bax protein ratio(r=-0.9759,P<0.01).