依托咪酯后处理对大鼠脑缺血再灌注时细胞凋亡的影响

目的 评价依托咪酯后处理对大鼠脑缺血再灌注时细胞凋亡的影响.方法 清洁级健康雄性SD大鼠32只,体重250～300 g,采用随机数字表法,将大鼠随机分为4组(n=8):假手术组(S组)、缺血再灌注组(I/R组)、脂肪乳组(L组)和依托咪酯后处理组(Ep组).采用栓塞右侧大脑中动脉2h恢复灌注的方法制备大鼠脑缺血再灌注模型.Ep组于再灌注即刻腹腔注射依托咪酯乳剂20 mg/kg(1 ml/100 g),I/R组和L组分别给予等容积生理盐水和脂肪乳.于再灌注24h时处死大鼠,取缺血侧脑组织,HE染色后光镜下观察病理学结果,采用TUNEL法检测凋亡细胞,计算凋亡指数,采用免疫组化染色法测定Bcl-2和Bax的表达,计算Bcl-2与Bax表达的比值(Bcl-2/Bax).结果 与S组比较,I/R组、L组和Ep组细胞凋亡指数升高,Bcl-2和Bax表达上调,Bcl-2/Bax升高(P＜0.05)；与I/R组和L组比较,Ep组细胞凋亡指数降低,Bcl-2表达上调,Bax表达下调,Bcl-2/Bax升高(P＜ 0.05);I/R组和L组上述指标差异无统计学意义(P＞0.05).Ep组脑组织病理学损伤较I/R组明显减轻.结论 依托咪酯后处理减轻大鼠脑缺血再灌注损伤的机制与调节Bcl-2和Bax的平衡表达,抑制细胞凋亡有关.

Effects of etomldate postconditlonlng on apoptotds In a rnt model of focal cerebral lschemia-reperhrslon In- jury

Objective To investigate the effects of etomidate postconditioning on apoptosis in a rat model of focal cerebral ischemia-reperfusion(I/R) injury.Methods Thirty-two pathogen-free male SD rats weighing 250-300 g were randomly divided into 4 groups ( n =8 each) using random number table:group sham operation ( group S); group focal cerebral I/R; group lipid emulsion (vehicle for etomidate) (group L) and group etomidate postconditioning (group Ep).Focal cerebral I/R was induced by inserting a nylon thread with rounded tip into right internal carotid artery.The thread was advanced cranially until resistance was met.Middle cerebral artery was occluded for 2 h in groups I/R,L and Ep.Normal saline,lipid emulsion and etomidate emulsion 20 mg/kg were injected peritoneally at the end of ischemia in groups I/R,L and Ep respectively.The animals were sacrificed at 24 h of reperfusion and their brains were removed for microscopic examination,assessment of apoptosis (by TUNEL) and detection of Bcl-2 and Bax expression ( by immuno-histochemistry).Apoptosis index ( AI =the number of apoptofic neurons/the total number of neurons examined × 100％ ) and Bcl-2/Bax ratio were calculated.Results I/R induced microscopic changes,significantly increased AI and Bcl-2 Bax ratio and up-regulated Bcl-2 and Bax expression in group I/R as compared with group S.Etomidate postconditioning significantly amefiorated brain damage,decreased AI,increased Bcl-2/Bax ratio,up-regulated Bcl-2 expression and down-regulated Bax expression in ischemic cerebral hemisphere in group Ep as compared with group I/R.There was no significant difference in brain damage,AI and Bcl-2 and Bax expression and Bcl-2/Bax ratio between groups I/R and L.Conclusion Etomidate postconditioning can attenuate focal cerebral ischemia-reperfusion injury in rats by inhibiting apoptosis and modulating Bcl-2 and Bax expression.