梓醇对局灶性脑缺血大鼠感觉运动皮质轴突再生限制性微环境的影响

目的观察梓醇对大鼠局灶性脑缺血后对侧感觉运动皮质轴突再生限制性微环境的影响。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。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进行干预,每天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检测对侧感觉运动皮质Nogo-A及其受体NgR蛋白表达。结果 Nogo-A阳性细胞被Cy3标记,胞质和突起呈红色,细胞核未见红色荧光。假手术组可见少量Nogo-A阳性细胞,模型组Nogo-A阳性细胞数较假手术组明显增加(P<0.05);梓醇中、高剂量组Nogo-A阳性细胞数较模型组和胞磷胆碱组明显减少(P<0.05)。NgR阳性细胞被FITC标记,具有神经元形态特征,胞质和突起呈绿色,细胞核未见绿色荧光。假手术组可见少量NgR阳性细胞,模型组NgR阳性细胞较假手术组稍增加(P>0.05);梓醇呈剂量依赖性下调NgR表达,中、高剂量组NgR阳性细胞数均比模型组和胞磷胆碱组明显减少(P<0.05)。Western blot分析与免疫荧光原位检测结果一致。结论梓醇下调脑缺血大鼠感觉运动皮质Nogo-A及其受体NgR蛋白表达,有助于改善轴突再生限制性微环境。

Effects of catalpol on the inhibitory microenvironment for axon regeneration in sensorimotor cortex in rats after focal cerebral ischemia

Aim To investigate the effects of catalpol on the inhibitory microenvironment for axon growth and regeneration in contralesional sensorimotor cortex in rats with focal cerebral ischemia.Methods 42 adult Sprague-Dawley rats were randomly divided into 7 groups: sham operation group,model group,normal saline control group,low,middle and high doses of catalpol treatment groups(1,5 and 10 mg.kg-1,respectively) and citicoline treatment(0.5 g.kg-1) group.Rats were subjected to permanent occlusions of the right middle cerebral artery(pMCAO) and were intraperitoneally administered with either catalpol,citicoline or saline 24th h after pMCAO and daily for 7 days.Nogo-A and NgR protein expression in contralesional sensorimotor cortex were detected by immunohistochemical staining and Western blot analyses at the 15 th day after pMCAO.Results Nogo-A labeled with Cy 3,was localized to the cytoplasm and processes,but absent in the nuclei.In sham operation group,Nogo-A positive cells were observed in cortical areas examined.And in pMCAO model group,the number of Nogo-A positive cells was obviously elevated above the level in sham operation group(P < 0.05).However,compared with the model group or citicoline group,the number of Nogo-A positive cells was reduced significantly at the dose of 5 or 10 mg.kg-1 catalpol group(P < 0.05).NgR labeled with FITC was also localized to the cytoplasm and processes,and absent in the nuclei of all positive cells.The number of NgR immunopositive cells was relatively low in sham operation group,but increased slightly in model group(P > 0.05).Compared with the model group or citicoline group,the number of NgR positive cells was reduced noticeably in catalpol treatment groups except low dose sub-group,which indicated that catalpol down-regulated the NgR expression in a dose-dependent manner(P < 0.05).Similar results above were determined by Western blot analyses.Conclusion Catalpol contributes to remodeling inhibitory microenvironment for axon regeneration through down-regulation of Nogo-A and NgR protein expression in contralesional sensorimotor cortex after pMCAO.