瑞替加滨对大鼠局灶性缺血再灌注损伤的保护机制

摘要

目的 研究M型钾离子通道开放剂瑞替加滨(retigabine,RTG)对大鼠局灶性缺血再灌注损伤的影响.方法 选取SD大鼠110只,随机分为假手术组(10只,Sham组),模型对照组(20只,MCAO组),治疗组(80只,RTG组).按照给药时间再将RTG组分为0 h、1 h、3 h及6 h 4个亚组,每组20只.采用线栓-再通法建立大鼠模型,于脑缺血2 h后恢复灌注.RTG组经尾静脉注射瑞替加滨10.5 m g/kg,假手术组和缺血再灌注组给予等量生理盐水.比较脑梗死体积变化,并进行神经功能评分,检测各组大鼠缺血半影区星形胶质细胞的增殖和半胱氨酸蛋白酶-3(Caspase-3)的表达,观察梗死皮质区域神经元的存活数量.结果 Sham组未发现脑梗死病灶,无神经功能损伤,Caspase-3阳性细胞及星形胶质细胞少见,脑皮质含有大量神经元.MCAO组和RTG组均可见大脑中动脉供血区梗死灶及神经功能损伤,但RTG治疗组梗死体积及神经功能评分均较MCAO组明显减少(P<0.05),RTG6h组较其他给药组大鼠脑梗死体积及神经功能评分增加(P<0.05).MCAO组大鼠梗死周围区Caspase-3阳性细胞数、星形胶质细胞明显增多,梗死区神经元数量明显减少,但RTG各组大鼠梗死周围区Caspase-3阳性细胞数、星形胶质细胞均较MCAO组明显下降(P<0.05),梗死区神经元的存活数量明显增加(P<0.05),RTG0h组、RTG1h、RT G3h组最为明显.结论 瑞替加滨对缺血性脑卒中具有脑保护作用,其机制可能是降低神经细胞的兴奋性,减轻缺血半影区的炎症反应,从而抑制细胞凋亡.瑞替加滨的脑保护作用具有时间依赖性,即超过一定的时间窗,脑保护作用会减弱.%Objective To studies impacts of retigabin ,a M-type potassium channel opener ,on focal cerebral ischemia/reper-fusion induced neural injury .Methods Totally 110 SD rats were randomly divided six groups :sham group (n=10) ,MCAO group (n=20) and RTG-treatment group .RTG-treatment group was also divided into RTG0h group (n=20) ,RTG1h group (n=20) , RTG3h group (n=20) and RTG6h group (n=20) .The temporary middle cerebral artery occlusion reperfusion model was made by the suture method ,reperfusion 2 hours after cerebral ischemia .In RTG-treatment groups ,a single dose of 10.5 mg/kg RTG was injected at the designated varying time points (at 0 hour ,1 hour ,3 hours and 6 hours after the reperfusion) .The sham-opera-ted group and MCAO group received the same volume of saline .Infarct size was measured ;the neurological function was scored . The number of astrocytes and Caspase-3(+ ) cells in the ischemic penumbra ,and neurons in the infarct area were detected .Results In the sham group ,no infarction was observed ,hippocampal neurons had no obvious change ,astrocytes and caspase-3(+ ) cells were hardly to be found ,a large number of neurons can be found .MCAO group and RTG group showed cerebral artery infarction and the damage of neurological function ,but the infarction volume and neurological outcome scores of the RTG-treatment group were lower than those of the MCAO group (P<0.05) .Compared with RTG0h ,RTG1h and RTG3h group ,the cerebral infarction volume and neurological outcome scores of RTG6h group were significantly increased (P<0.05) .A lot of astrocytes and caspase-3(+ ) cells were found in the MCAO group ,however ,only very few neurons were found in the infarct zone .Compared with the MCAO group ,the expressions of astrocytes and caspase-3(+ ) cells decreased significantly and the number of surviving neurons was significantly increased in the RTG-treatment group (P<0.05) ,especially at 0 hour ,1 hour and 3 hours group ,when compared with RTG6h group .Conclusion RTG has protective time-dependent effect in cerebral ischemic reperfusion injury .