梓醇上调局灶脑缺血大鼠缺血灶周围大脑皮质BDNF和TrkB蛋白表达

摘要

目的 观察梓醇对局灶脑缺血大鼠缺血灶周围大脑皮质BDNF及其受体TrkB蛋白表达的影响,探讨梓醇促神经修复作用分子基础.方法 SD大鼠42只,随机分为假手术组、模型组、生理盐水组、梓醇低、中、高剂量治疗组(剂量分别为1、5、10 mg·kg-1)和胞磷胆碱(剂量为0.5 g·kg-1)对照组.开颅电凝右侧大脑中动脉制备局灶永久性脑缺血模型,造模后24 h,首次经腹腔注射梓醇或胞磷胆碱进行干预,每日1次,连续7 d.于造模后15 d断头取脑,制备脑片和脑组织匀浆,采用免疫荧光组织化学染色和Western blot检测缺血灶周围大脑皮质BDNF及其受体TrkB蛋白表达.结果 BDNF阳性细胞被Cy3标记,具有神经元的形态特征,胞质和突起呈现红色,细胞核未见红色荧光.缺血灶周围大脑皮质BDNF阳性细胞数模型组和生理盐水组均较假手术组明显增加(P＜0.05),梓醇1、5、10 mg·kg-1剂量组均较模型组明显增加(P＜0.05),且梓醇5、10 mg·kg-1剂量组明显高于胞磷胆碱组(P＜0.05).TrkB阳性细胞被FITC标记,具有神经元形态特征,胞质和突起呈现绿色,胞核未见绿色荧光.TrkB阳性细胞数模型组较假手术组有减少趋势,但差异无显著性(P＞0.05);梓醇5 mg·kg-1剂量组较模型组和胞磷胆碱组明显增加(P＜0.05).Western blot检测结果与免疫荧光原位检测结果一致.结论 梓醇上调局灶脑缺血大鼠缺血灶周围大脑皮质BDNF及其受体TrkB蛋白表达,有助于模型大鼠神经缺失功能恢复.%Aim To observe the effects of catalpol on the expression patterns of brain-derived neurotrophic factor ( BDNF ) and its tropomyosin-related kinase receptor B( TrkB )proteins within the peri-infarct cortex in rats with focal cerebral ischemia, so as to investigate the molecular basis on which catalpol promotes neuro-repairment after stroke. Methods 42 adult Sprague-Dawley rats were randomized into 7 groups, including sham operation group, model group, normal saline control group, low dose, middle dose and high dose catalpol treatment groups( 1 , 5 and 10 mg · kg-1 , respectively ) and citicoline treatment group ( 0. 5 g · kg-1 ). Rats were subjected to permanent occlusions of the right middle cerebral artery ( pMCAO ) and were intraperitoneally administered with either catalpol, citicoline or saline 24h after pMCAo daily for 7 days. BDNF and TrkB protein in the peri-infarct cortex were detected via immunohistochemical staining and Western blot analyses at the time point of 15th day after pM-CAO. Results BDNF positive cells were labeled with Cy3 , and the red immunofluorescence was localized to the cytoplasm and processes, while absent in the nuclei. BDNF positive cells with neuronal morphologic characteristics were observed in cortical areas examined. The number of BDNF positive cells in the pM-CAO model group was increased, compared with the sham operation group, there was a significant differ-ence( P 0. 05 ); compared with the normal saline group or the citicoline group, catalpol at the dose of 5 mg · kg-1 remarkably up-regulated TrkB positive cells, there was a significant difference( P < 0. 05 ). Similar results were determined by Western blot analyses. Conclusion Catalpol can up-regulate the protein expression of BDNF and TrkB within the peri-infarct cortex , which would contribute to the functional recovery of rats with ischemic stroke.