梓醇促进局灶脑缺血大鼠皮质脊髓束芽生和重塑

目的观察梓醇对局灶脑缺血大鼠病灶对侧皮质脊髓束(corticospinal tract,CST)轴突芽生和重塑的影响。方法30只SD大鼠随机分为假手术组、模型组、生理盐水组、梓醇治疗组和胞磷胆碱对照组。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(5 mg·kg-1)或胞磷胆碱(0.5 g·kg-1),每日1次,连续7d。采用黏贴物移除实验和足失误实验测试受累前肢(左前肢)功能状况;核磁共振(MRI)测量脑梗死体积;生物素化葡聚糖胺(biotinylated dextran amine,BDA)顺行示踪健侧CST,检测脊髓颈膨大区健侧CST越边至失神经支配侧的纤维数量,了解脊髓颈膨大区CST轴突重塑;免疫荧光双标脊髓颈膨大区BDA标记纤维与生长相关蛋白(growth-associatedprotein,GAP-43),检测BDA/GAP-43共定位信号,了解脊髓颈膨大区CST轴突芽生能力。结果造模后7、14、21和28d,梓醇组和胞磷胆碱组左前肢黏贴片移除时间均比模型组和生理盐水组明显缩短(P<0.05),左前肢失误率也较模型组和生理盐水组明显降低(P<0.05);其中,造模后28 d时,梓醇组左前肢感觉运动功能状况明显优于胞磷胆碱组(P<0.05)。造模后1和28 d,各组脑梗死体积差异无显著性(P>0.05)。造模后28 d,梓醇组脊髓颈膨大区健侧CST越边纤维占(8.5%±2.1%),较模型组(4.7%±1.3%)和胞磷胆碱组(5.5%±1.8%)明显增加(P<0.05);梓醇组脊髓颈膨大区BDA/GAP-43共定位信号明显强于模型组和胞磷胆碱组(P<0.05)。结论梓醇可增强缺血性脑卒中大鼠皮质脊髓束轴突芽生和重塑能力,有助于受累肢体感觉运动功能恢复。

Catalpol promotes corticospinal tract sprouting and remodeling after focal cerebral ischemic stroke in rats

Aim To investigate the therapeutic effects of catalpol on the contralesional corticospinal tract(CST)axonal sprouting and remodeling after focal cerebral ischemic stroke in adult rats.Methods Thirty adult Sprague-Dawley rats were randomized into 5 groups,including sham operation group,model group,saline group,catalpol treatment group and citicoline treatment group.Rats were subjected to permanent right middle cerebral artery occlusions(pMCAO) via electrocoagulation.Animals were treated intraperitoneally with either saline,catalpol(5 mg·kg-1) or citicoline(0.5 g·kg-1) 24h after pMCAO and daily for 7 days,respectively.An adhesive-removal test and a foot-fault test were performed to evaluate functional recovery.MRI was employed to measure the lesion volume.Biotinylated dextran amine(BDA) was injected into the left motor cortex to anterogradely label the corticospinal tract(CST) at 15 day after pMCAO.Animals were euthanized 2 weeks after injection.BDA labeling axons sprouting originating from the contralesional cortex into the denervated side of the cervical enlargement of spinal cord were detected using immunohistochemistry.And the colocalization of BDA labeling axons terminals and the growth-associated protein-43(GAP-43) within the cervical enlargement of spinal cord were further investigated by Immunofluorescence double labeling technology.Results Compared with model animals or saline treated animals,significant functional improvements were evident in rats treated with catalpol or citicoline at 7,14,21 and 28 days post-pMCAO(P<0.05).Especially,functional recovery status in catalpol treatment group was superior to the citicoline treatment group at day 28 after pMCAO(P<0.05).However,there was no significant difference in lesion volume among the different treatment groups at 1 day and 28 day after pMCAO(P>0.05).Furthermore,BDA anterogradely labeling exhibited that catalpol markedly enhanced the number of axon branches originating from the contralesional cortex into the denervated side of the enlargement of cervical spinal cord compared with either model group or citicoline treatment group(P<0.05).In addition,double Immunofluorescence staining with the anti-GAP-43 combined with BDA traced axon illustrated that catalpol enhanced CST axonal growth potential,as determined by a significant increase of the number of GAP-43/BDA double labeled sprouting axons in the catalpol treatment group compared with that in model group,saline group or citcoline group.Conclusion Catalpol treatment enhances corticospinal tract axonal sprouting and rewiring into the denervated spinal cord which may facilitate functional recovery after focal cerebral ischemia.