一氧化氮供体及前体对大鼠脑缺血再灌注损伤保护机制的探讨

Study on the Protection of NO Donator and Precursor in Cerebral Ischemia/Perfusion Model Rats

目的观察介入给药一氧化氮(NO)供体硝酸甘油(Nitroglycerine,NG)及前体L-精氨酸(L-Arginine,ARG)对大鼠脑缺血再灌注后海马区星形胶质细胞表达的胶质纤维酸性蛋白(GFAP)的影响,探讨NG及ARG的脑保护机制。方法采用大鼠大脑中动脉阻塞(MCAO)法建立局灶性脑缺血模型。将大鼠随机分为假手术组、MCAO组、NG组和ARG组。MCAO组、NG组和ARG组于缺血2h再灌注同时分别局部介入给予生理盐水、NG和ARG,于再灌注3h或24h时,荧光法检测血清NO含量。并在3h或24h时处死大鼠,病理分析脑梗死体积以及免疫组织化学法检测海马区GFAP表达情况。结果缺血再灌注后3h血清NO升高(P<0.01),治疗组较MCAO组明显(P<0.01),GFAP表达阳性细胞数增加,但治疗组较MCAO组减少(P<0.01),各组大鼠脑组织未出现肉眼可见梗死灶;缺血再灌注后24h,血清NO治疗组较3h降低,而MCAO组较3h升高(P<0.05),GFAP表达阳性细胞数较3h增加(P<0.01),治疗组较MCAO组减少(P<0.01),TTC染色显示脑梗死体积治疗组较MCAO组减小(P<0.05)。结论脑缺血再灌注后海马区脑组织GFAP表达增强,通过局部介入给予NG、ARG增加NO合成,抑制GFAP高表达,减小脑梗死体积。提示NG、ARG抗脑缺血性损伤的保护机制可能与抑制星形胶质细胞过度表达有关。

Objective To observe the effect of interventional injection nitric oxide(NO) donor/precursor(Nitroglycerine /L-Arginine,NG/ARG) on the expression of glial fibrillary acidic protein(GFAP) in rat's hippocampus with cerebral ischemia/reperfusion,so as to investigate their possible protective mechanism on cerebral ischemic injury.Methods We made the models of focal ischemic rat's brain through middle cerebral artery occlusion(MACO).All the mice were divided into sham-operated group,MCAO group,NG group and ARG group randomly.At 2h after ischemic reperfusion,normal saline,NG and ARG were administered respectively to the MCAO,NG and ARG groups by interventional injection.At 3h and 24h after reperfusion,we assessed the infarct volume by imagine analysis and detected the expression of GFAP by immunohistochemistry staining method,the level of NO in serum by fluorescence estimation.Results At 3h after reperfusion,the level of NO in serum increased significantly(P<0.01),which was more apparent in therapeutic group than in MCAO group(P<0.01).The quantity of positive cells which expressed GFAP in therapeutic group was less than that in MCAO group(P<0.01).There was no ischemic area in rat's brain of all the groups at 3h after reperfusion.At 24h after reperfusion,the level of NO in serum decreased in therapeutic group compared with 3h after reperfusion,but increased significantly in MCAO group(P<0.05).While,the quantity of positive cells which expressed GFAP was more than that at 3h after reperfusion(P<0.01),and the change in therapeutic group was less than in MCAO group(P<0.01).The infarct volume in therapeutic group was smaller than that in MCAO group at 24h after reperfusion(P<0.05).Conclusion Administration of NG and ARG by means of interventional injection in the early stage of ischemia can increase the synthesis of NO,and inhibit high expression of GFAP after ischemic reperfusion in hippocampus,and it can also decrease the infarct volume.The protection of NG and ARG against ischemic injury may be related to its inhibiting the activation of astrocytes.