电针影响大鼠脑缺血再灌注后水通道蛋白4 (AQP4)的表达及其在血管周边的分布

 目的 研究电针干预大鼠脑缺血再灌注损伤时脑内水通道蛋白4 (aquaporin 4,AQP4)的表达与分布改变。 方法 选用SD雄性大鼠406只,分为正常对照组(n=40),脑缺血组(n=138),脑缺血+电针组(电针处理组,n=138)和脑缺血+假电针组(n=90)。利用线栓法制作大鼠大脑中动脉阻塞(middle cerebral artery occlusion,MCAO)模型,缺血1 h后实施脑血流再灌注。电针处理组在脑缺血开始后立即给予电针刺激,穴位选择“水沟”(GV 26)与“百会”(GV 20)。利用Western blot检测AQP4的蛋白表达水平,胶体金免疫电镜观察AQP4免疫阳性颗粒在血管周边的分布,常规焦油紫染色计算脑缺血后的脑梗死体积以及脑肿胀程度。神经行为学评估通过Garcia量表进行评分。结果 (1)再灌注24 h内,电针可下调因脑缺血而诱导的AQP4表达升高,再灌注后6 h和12 h分别是缺血组的0.63倍和0.72倍(P < 0.05);(2)与正常对照组相比,血管周边AQP4的免疫阳性颗粒在再灌注后6 h增多,在再灌注后24 h减少,电针干预组中血管周边AQP4的免疫阳性颗粒密度发生改变,其变化与缺血组相反,差异有统计学意义(P < 0.05);(3)电针减轻脑缺血后的脑梗死及脑肿胀,促进神经行为功能的恢复。结论 电针下调因缺血而导致的AQP4蛋白的表达升高,并动态改变其在血管周边的分布。电针对AQP4的调控作用可能与电针的神经保护作用机制相关。

Electroacupuncture modulates the expression and perivascular distribution of aquaporin 4 (AQP4) in rats during cerebral ischemia/reperfusion

Objective To investigate whether the aquaporin4 (AQP4) protein expression and distribution is involved in the anti edema protective effect of electroacupuncture (EA).Methods A total of 406 adult male SD rats were divided into normal control (n=40),cerebral ischemia group (n=138),ischemia plus EA group (n=138) and ischemia plus sham EA group (n=90).One hour focal cerebral ischemia was induced by middle cerebral artery occlusion.EA was delivered to acupoints Baihui (GV 20) and Shuigou (GV 26) immediately after ischemia onset in ischemia puls EA group.AQP4 protein expression and polarized distribution were assessed by Western blot and pre embedding immunogold labeling,respectively.Cerebral infarction and edema were detected by cresyl violet staining.Neurological deficits were evaluated according to Garcia′s score index.Results (1) EA reduced ischemia induced upregulation in AQP4 protein expression in the early stage of ischemia/reperfusion injury.The expression levels decreased to 0.63 and 0.72 folds of those in ischemic groups at 6 and 12 hours post reperfusion,respectively.(2) Perivascular immuno labeling density of AQP4 (gold particles / μm) increased at 6 hours post reperfusion and declined at 24 hours after reperfusion.After EA treatment,the AQP4 density in perivascular astrocyte endfeet significantly decreased at 6 hours of reperfusion and rose at 24 hours of reperfusion.(3) EA reduced ischemic infarction and brain swelling,and improved neurological behavior after focal cerebral ischemia/reperfusion injury.Conclusions EA reduces ischemia induced upregulation of AQP4 protein and dynamically modulates the perivascular distribution of AQP4 in ischemic rat.These effects may be involved in the beneficial effects of EA in reducing ischemic edema and infarction,and thereafter,improving neurological outcome.