葛根素预处理对脑缺血再灌注大脑皮质微血管和血脑屏障的预防性保护作用

Preventive protection exerted by puerarin pretreatment on microvessel and blood brain barrier in the cerebral cortex with ischemia reperfusion

目的:探讨葛根素(Pue)对缺血再灌注(IR)大鼠大脑皮质微血管和血脑屏障预防性保护作用.方法:SD大鼠随机分为假手术组(Sham组)、IR组、葛根素组和尼莫地平组(NIM组);葛根素组、NIM组分别于术前给予葛根素50 mg·kg-1·d-1、NIM 1mg· kg-1·d-1预处理,制备大脑中动脉阻塞脑缺血再灌注模型;单宁酸-氯化铁法(TA-Fe法)显示大脑皮质微血管,图像定量分析微血管密度(MVD)和微血管面积比(MVA);伊文思蓝(EB)和干湿重法检测脑组织含水量和血脑屏障(BBB)通透性,透射电镜观察大脑皮质BBB的超微结构变化.结果:与IR组相比,葛根素组脑组织含水量和微血管通透性明显降低,MVD、MVA显著增高,葛根素组与尼莫地平组差异无统计学意义.葛根素组、尼莫地平组的大脑皮质缺血区BBB超微结构变化接近,都表现为内皮细胞肿胀减轻,紧密连接趋于正常,基膜松散但连续,胶质膜排列较致密.结论:葛根素预处理可通过减轻微血管损伤、增加再通数量,降低血脑屏障的通透性,减轻脑水肿,预防性保护缺血再灌注损伤脑组织.

Objective:To investigate the preventive protection exerted by puerarin pretreatment on microvessel and blood brain barrier（BBB） in the cerebral cortex with ischemia reperfusion.Methods:SD rats were randomly divided into sham operation group（Sham group）,ischemia reperfusion group（IR group）,puerarin group（Pue group） and nimodipine group（NIM group）.Pue group and NIM group were administrated with puerarin intragastrically one week before in 50 mg·kg-1·d-1and 1 mg·kg-1·d-1 respectively.Then the focal ischemia reperfusion models were established by ligating middle cerebral artery.TA-Fe method was applied to observe the microvessels in the cerebral cortex.Quantitative analysis image system was used to analyze the microvessel density（MVD） and the microvessel area density（MVA） quantitatively in cerebral cortex;and the amount of Evans blue containing and water content in brain tissue were detected,then the ultrastructural changes of blood brain barrier were observed by transmission electron microscopy.Results:The amount of Evans blue and water content were significantly decreased compared to the IR group,while the MVD and MVA were significantly increased.There was no significant differences between Pue group and NIM group;the ultrastructural alterations of BBB were almost the same.These changes were manifested by alleviating the degree of endothelial swelling;the tight junction of the endothelial approached to normal state;the base membrane became loose but still remained uninterrupted,and the glial membrane was relatively closely arranged.Conclusion:Preventively avoiding reperfusion injuries of brain tissues can be achieved by puerarin pretreatment through inhibiting the microvessel injury,increasing the number of recanalization,reducing BBB permeability,and decreasing the cerebral edema.