脑缺血再灌注后大鼠海马Wnt7b的表达

目的   研究成年大鼠脑缺血再灌注后海马齿状回颗粒细胞下层（SGZ）Wnt7b的表达。方法   将44只雄性Wistar大鼠随机分为正常对照组和脑缺血再灌注组，线栓法制备大鼠脑缺血再灌注损伤模型，缺血90min，术后检测神经功能缺失和脑梗死，在脑缺血再灌注后1、3、7、14d取大鼠海马组织。RT-PCR技术检测Wnt7b mRNA表达水平；免疫荧光技术检测海马Wnt7b蛋白及β-catenin蛋白表达水平。结果   脑缺血后，大鼠出现严重的脑梗死和神经功能障碍,随再灌注时间延长，大鼠神经功能得到修复。再灌注7d后，健侧脑组织海马Wnt7b mRNA表达上调（P＜0.05），缺血侧脑组织海马Wnt7b mRNA的表达明显上调（P＜0.01）。Wnt7b主要分布于SGZ附近，阳性细胞增多（P＜0.01），且该脑区的细胞内β-catenin阳性细胞数目增多（P＜0.01）。结论   缺血性脑损伤可刺激Wnt7b在成年海马SGZ的表达上调，Wnt7b可能通过经典Wnt通路参与调节脑缺血后成年海马SGZ的神经发生。

Expression and location of Wnt7b in rat subgranular zone of hippocampus dentate gyrus after cerebral ischemia-reperfusion

Objective   To investigate the involvement of Wnt in ischemia-induced adult nerve regeneration and explore the mechanism of the two members．Methods   44 normal male Wistar rats were randomly divided into 2 groups: the normal control group and the cerebral ischemia group. Cerebral ischemia-reperfusion rat models were established by inserting a proper thread in the right middle cerebral artery and removing the thread after 90min.Infarction and neurological deficit scores were evaluated after the operation. RT-PCR was used to investigate the expression of Wnt7b mRNA in hippocampus. Immunohistochemistry was used to investigate  expressions of Wnt7b and β-catenin proteins in the dentate gyrus of hippocampus. Results   Severe infarction appeared 1 day after ischemia-reperfusion, with  obvious neurological deficit. Neural function′s were  improved as time progressed. Expressions of Wnt7b mRNA in health side and  ischemic side were significantly upregulated, and  it  was more obvious in  ischemic side  （P＜0.01）than  in contralateral side（P＜0.05）. Consistent with the level of Wnt7b mRNA, the amount of Wnt7b positive cells dramatically increased in close proximity to the subgranular zone (SGZ) of the dentate gyrus in hippocampus（P＜0.01）, and the immunostaining of β-catenin, a primary element of classical Wnt signalling pathway, also significantly increased（P＜0.01）. Conclusion   Ischemia injury stimulated the expressions of Wnt7b and β-catenin in SGZ of hippocampus in adult rats. Wnt7b might be involved in the neurogenesis in SGZ of adult hippocampus after  cerebral ischemia by the classical Wnt signalling pathway.