梓醇对大鼠梗死灶周围大脑皮质神经元树突生长及突触素表达的影响

目的观察梓醇对局灶脑缺血大鼠梗死灶周围大脑皮质(peri-infarction cortex,PIC)锥体神经元树突生长及突触素p38蛋白表达的影响,探讨其促脑卒中后神经修复作用及机制。方法 57只清洁级成年SD大鼠,随机分为假手术组,模型组,生理盐水组,梓醇低、中、高剂量(分别为1、5、10 mg·kg-1)组和胞磷胆碱(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。于造模后24 h开始腹腔注射不同剂量梓醇或胞磷胆碱,每日1次,连续7d。术后1、4、7和15 d采用角落实验评估神经缺失功能恢复状况;术后1 d和15 d磁共振成像测量脑梗死体积;术后15 d,断头取脑,Golgi-Cox染色显示PIC区锥体神经元树突变化,免疫荧光组织化学染色及Western blot检测PIC区突触素p38蛋白表达。结果梓醇各剂量组和胞磷胆碱组术后7 d和15 d神经功能恢复明显优于模型组和生理盐水组(P<0.05);术后1 d、15 d,各实验组脑梗死体积差异无显著性(P>0.05);梓醇中剂量组PIC区锥体神经元树突分支数和树突棘密度均比模型组、生理盐水组和胞磷胆碱组明显增加(P<0.05);梓醇各剂量组PIC区突触素p38表达均比模型组、生理盐水组和胞磷胆碱组明显上调(P<0.05)。结论梓醇可增强局灶脑缺血大鼠PIC区锥体神经元树突可塑性,上调突触素p38表达,促进神经缺失功能恢复。

Effects of catalpol on dendritic outgrowth and synaptophysin expression in the peri-infarct cortex of rats with permenant middle cerebral artery occlusion

Aim To investigate the possible mechanisms underlying the observed functional recovery and to observe the effects of catalpol on the dendritic outgrowth and the expression of synaptophysin in the peri-infarct cortex(PIC) in rats with focal permenant cerebral ischemia.Methods Sprague Dawley rats were randomly divided into 7 groups,including sham operation group,permenant middle cerebral artery occlusion(pMCAO) model group,normal saline group,low,middle and high doses of catalpol treatment groups(1,5 and 10mg·kg-1,respectively) and citicoline treatment group(0.5 g·kg-1).A permenant focal cerebral ischemia model was established by pMCAO with modified craniectomy electric-coagulation method,and then 24h after pMCAO treated with catalpol once a day for 7 days.The corner tests were performed to evaluate the sensorimotor integration functional status before operation(baseline) and at 1d,4d,7d and 15d after pMCAO by a blinded investigator.Lesion volume was measured with magnetic resonance imaging(MRI) at 1d(before treatment) and 15d after pMCAO.Rats were sacrificed 15days after pMCAO and brains were removed to detect the expression of synaptophysin by immunofluorescence staining and Western blot.In addition,brains were processed for Golgi-Cox staining procedure to show the changes of dendritic branches and spine density of pyramidal neurons in the peri-infarct cortex.Results The neurological functions in different doses of catalpol treated groups and citicoline group were better on 7 d and 15 d after pMCAO as compared with those in the pMCAO model group and the normal saline group(P<0.05).However,there was no significant difference in lesion volume among the control and different treatment groups.Animals treated with catalpol in dose of 5 mg·kg-1 showed an increase in the number of dendritic branches and spine density compared with either pMCAO model group,normal saline group or citicoline group(P<0.05).The expression of synaptophysin was significantly up-regulated in groups treated with different doses of catalpol in comparison with either model group,saline group or citicoline group(P<0.05),as revealed by both immunofluoresence staining and Western blot.Conclusion Catalpol can promote functional recovery after focal ischemic stroke in association with up-regulation of the synaptophysin protein expression and improve the neuronal dendritic plasticity in the peri-infarct cortex.