氯胺酮对大鼠脑缺血后解偶联蛋白2的影响

目的 探讨氧胺酮对大鼠前脑缺血-再灌注(I/R)后海马解偶联蛋白2(uncoupling proteins 2,UCP 2)表达的影响及在脑保护作用中的机制. 方法 45只体质量在250～300 g的雄性Wistar大鼠随机分为3组,每组15只.双侧颈总动脉夹闭加放血降压再回输法建立前脑缺血-再灌注模型,大鼠脑电图出现低幅持续性7 Hz、30～40μV的θ节律为脑缺血模型成功标志.对照组(C组):仅暴露双侧颈总动脉,未放血降压及夹闭双侧颈总动脉;缺血损伤组(1组):放血法使平均动脉压降到(40±5)mmHg时,夹闭双侧颈总动脉10 min,侧脑室内注射生理盐水(1.0 mg/kg);氯胺酮干预组(K组):放血降压、夹闭双侧颈总动脉与Ⅰ组相同,侧脑室内注射氯胺酮(1.0 mg/kg).于再灌注6 h后断头取脑组织,光镜下观察脑组织病理学改变;半定量逆转录.聚合酶链反应(RT-PCR)技术检测海马UCP 2mRNA表达(n=7);免疫组织化学(IH)法检测海马UCP2蛋白表达(n=8).RT-PCR、IH结果应用方差分析(ANOVA)进行统计学分析. 结果 与C组UCP2 mRNA(0,91±0.02)表达比较,Ⅰ组脑I/R后6h UCP2 mRNA(1.06±0.02)和K组脑I/R后6 h UCP2 mRNA(1.18±0.06)表达升高(P<0.05),K组脑I/R后6 h UCP 2 mRNA表达高于Ⅰ组(P<0.05);C组UCP2蛋白少量表达(17.91±5.49),Ⅰ组脑I/R后6 h UCP2蛋白(31.56±4.01)和K组脑I/R后6 h UCP2蛋白(44.61±4.96)表达升高(P<0.05).K组脑I/R后6 h UCP2蛋白表达高于Ⅰ组(P<0.05). 结论 氯胺酮促进大鼠前脑缺血-再灌注(I/R)后海马UCP 2 mRNA和蛋白的表达,可能是其对脑缺血-再灌注损伤保护作用的机制之一.

Effect of ketamine on UCP 2 expression after cerebral ischemia-reprfusion in rats

Objective To investigate the effect of ketamine on hippocampal uncoupling protein 2 (UCP 2) expression after forebrain ischemia-reperfusion (I/R) in rats and the mechanism of protective effect of ketamine on brain. Method Forty-five male Wistar rats weighing 250～300 g were randomly divided into 3 groups, with 15 animals in each group. Forebrain I/R was estabhshed by occlusion of bilaleral carotid artery combined with hy-potemion,EFG in a sustained low rate of 7 Hz, 30～40 μVθ rhythm was the success signs of forebrain I/R. Con-trol group (C) :sham operation was performed; I/R group (Ⅰ): bilateral common carotid arteries were clamped for lOmin combined with hypotension [MAP:(40±5) mmHg] induced by exsanguinations, then saline (1 mg/kg) was injected into the lateral cerebral ventricle using microsyringe; ketamine group (K):ketamine (1 mg/kg) was injected into the lateral cerebral ventricle using microsyringe after I/R. The animals were decapitated, the brain was immediately removed,and the hippocampal tissues were dissociated at 6 h after reperfusion. The cerebral I/R injury was observed with light microscope, the levels of UCP 2 mRNA expression in hippocampus were detected by using semi-quantitative RT-PCR technique (n=7), coronal sections including hippocampal tissue were obtained for detection of UCP 2 protein expression by immuno-histochemistry (IH) method (n=8). The RT-PCRR and IH data were expressed as the mean±SD, the statistical signiticance was determined by one-way ANOVA. Results The UCP 2 mRNA expression was (1.06±0.02) in group Ⅰ and (1.18±0.06)in group K increased significantly compared with that in group C(0.91±0.02) (P<0.05), there were more UCP2 mRNA expression in group K increased than that in group Ⅰ(P<0.05). The expression of UCP 2 protein was (31.56±4.01) in group Ⅰ and (44.61±4.96) in group K, increased significantly compared with that in group C (17.91±5.49) (P<0.05),there were more UCP 2 protein expression in group K than that in group Ⅰ (P<0.05). Conclusions Ketamine can attenuate the cerebral I/R injury in rats, the underlying mechanism may be related to the up-regulartion of the expression of hippocampal UCP 2 mRNA and UCP 2 protein.