NO-cGMP-PKG信号通路在天麻素促进脑缺血后海马神经发生中的作用

Gastrodin improves hippocampal neurogenesis by NO-cGMP-PKG signaling pathway in cerebral ischemic mice

研究天麻素(gastrodin,GAS)对脑缺血后海马神经发生的作用,并探讨其与NO相关可能机制。利用双侧颈总动脉夹闭法建立C57BL/6小鼠脑缺血模型,分别用HE染色和Morris水迷宫检测海马CA1区的病理形态及小鼠认知功能;免疫荧光染色检测Brd U/Neu N阳性细胞数;比色法、硝酸还原法分别检测NOS活力和NO含量;ELISA和Western blot法分别检测c GMP水平和PKG蛋白表达。术后8 d,小鼠海马CA1区锥体神经元结构不规则,出现明显核固缩,细胞排列松散,神经元数目明显减少;29 d空间学习和记忆能力下降。结果提示,小鼠出现了脑缺血损伤。同时,模型小鼠海马齿状回Brd U/Neu N阳性细胞数明显增加,提示脑缺血后海马出现神经发生。不同剂量GAS(50,100 mg·kg^-1)处理明显减轻小鼠CA1区的病理形态损伤,改善学习记忆能力,并促进海马神经发生。同时,模型组NOS-NO减少,但c GMP-PKG增加。GAS给药激活NOS,促进NO生成,增加c GMP水平,上调PKG表达。上述结果提示,GAS可促进脑缺血后海马神经发生,改善小鼠认知功能,该作用可能与NO-cGMP-PKG通路的激活有关。

This paper was aimed to investigate the effect of gastrodin(GAS)on hippocampal neurogenesis after cerebral was chemic and to explore its mechanism of action related to NO.The cerebral ischemia model of C57 BL/6 mice was established by bilateral common carotid artery occlusion.The pathological changes in hippocampal CA1 region and the cognitive function of mice were assessed by HE staining and Morris water maze test,respectively.The count of Brd U/Neu N positive cells in dentate gyrus was detected by immunofluorescence assay.The NOS activity and the NO content were determined by colorimetric and nitrate reduction methods,respectively.The level of c GMP was measured by ELISA kit,and the PKG protein expression was tested by Western blot.On postoperative day 8,the hippocampal CA1 pyramidal neurons of mice showed irregular structure,with obvious nuclear pyknosis,loose cell arrangement and obvious decrease in the number of neurons.On postoperative day 29,the spatial learning ability and memory were decreased.These results indicated cerebral ischemia in mice.Meanwhile,the Brd U/Neu N positive cells were increased significantly in ischemic mice,indicating that neurogenesis occurred in hippocampus after cerebral ischemia.Treatment with different doses of gastrodin(50 and 100 mg·kg^-1)significantly ameliorated the pathological damages in the CA1 region,improved the ability of learning and memory,and promoted hippocampal neurogenesis.At the same time,both the NOS activity and the NO concentration were decreased in model group,but the c GMP level was increased,and the PKG protein expression was up-regulated.Gastrodin administration activated the NOS activity,promoted NO production,further increased c GMP level and up-regulated PKG protein expression.These results suggested that gastrodin can promote hippocampal neurogenesis after cerebral ischemia and improve cognitive function in mice,which may be related to the activation of NO-cGMP-PKG signaling pathway.