可乐定对慢性脑缺血大鼠学习记忆及ERK信号通路相关蛋白的影响

目的:研究可乐定(clonidine)对大鼠慢性脑缺血(ischemia)后认知功能的影响并初步探讨其神经保护作用机制。方法:将45只SD大鼠随机分为假手术(sham)组、脑缺血(ischemia)组和可乐定(clonidine)组,每组15只。通过大脑中动脉栓塞法建立慢性脑缺血大鼠模型。各组大鼠在术前1周连续灌胃给药,其中clonidine组每日以clonidine 100μg/kg灌胃,sham组和ischemia组以等体积蒸馏水灌胃。术后4周,用Morris水迷宫法检测各组大鼠的学习记忆能力,免疫组织化学法和Western blot法检测非磷酸化和磷酸化细胞外信号调节激酶1/2(ERK1/2)及环磷腺苷效应元件结合蛋白(CREB)的蛋白水平。结果:Morris水迷宫实验结果显示,与假手术组相比,脑缺血组大鼠学习和记忆能力减弱;与脑缺血组相比,可乐定组大鼠学习和记忆能力增强。免疫组织化学法和Western blot法检测结果表明,与假手术组比较,脑缺血组大鼠海马组织中p-ERK1/2和CREB的蛋白水平均增加(P0.01);与脑缺血组相比,可乐定组大鼠海马组织中p-ERK1/2和p-CREB的蛋白水平降低(P0.01)。结论:可乐定可能通过调节ERK信号通路相关蛋白ERK1/2和CREB的表达,从而改善脑缺血再灌注引起的学习记忆障碍。

Effects of clonidine on learning and memory and protein levels of ERK signal pathway-related proteins in rats with chronic cerebral ischemia

AIM:To investigate the regulatory effects and underlying molecule-mechanism of clonidine on learning and memory in rats with chronic cerebral ischemia. METHODS:Sprague-Dawley rats (n=45) were randomly divided into sham-operation group, cerebral ischemia model group and clonidine group, 15 rats in each group. The chronic cerebral ischemia rat model was established by right middle cerebral artery occlusion for 2 h and reperfusion for 30 d. Clonidine was administrated by i.g. for 7 days in clonidine group. The ability of spatial reference memory of the rats with cerebral ischemia was tested by Morris water maze. The protein levels of extracellular signal-regulated kinase 1/2 (ERK1/2), phosphorylated ERK1/2 (p-ERK1/2), cAMP-response element binding protein (CREB) and phosphorylated CREB (p-CREB) were determined by immunohistochemistry and Western blot. RESULTS:The results of Morris water maze test showed that compared with the sham-operation group, the ability of spatial reference memory was obviously impaired in the cerebral ischemia model group. Compared with the cerebral ischemia model group, the ability of spatial reference memory in the clonidine group were improved. Compared with the sham-operation group, the protein levels of p-ERK1/2 and p-CREB in hippocampus were increased in model group (P<0.01). Compared with the cerebral ischemia model group, the protein levels of p-ERK1/2 and p-CREB in hippocampus were decreased in the clonidine group (P<0.01). CONCLUSION:Clonidine improves the learning and memory abilities of the rats with cerebral ischemia, and ERK1/2 and CREB are involved in this process.