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目的 研究肝X受体激活对全脑缺血/再灌注(ischemia/reperfusion,I/R)小鼠的海马神经干细胞增殖及认知功能的影响,及其作用机制.方法 将75只C57BL/6小鼠随机分为3组,即假手术组(Sham)、全脑缺血/再灌注组(I/R)、全脑缺血/再灌注+肝X受体激动剂TO901317干预组(L/R+TO90),每组25只.采用双侧颈总动脉夹闭方法建立全脑I/R小鼠模型;肝X受体激动剂TO901317 (30 mg·kg-1)在缺血后24 h腹腔注射(i.p,1次/天,连续14 d).Morris水迷宫实验测定小鼠学习与记忆等认知功能的改变;HE染色观察小鼠海马CA1区病理形态学的改变;免疫组化观察小鼠海马齿状回区DCX阳性细胞的表达;免疫荧光观察海马齿状回区BrdU阳性细胞的表达;Western blot检测海马LXRα、LXRβ、ABCA1、p-ERKl/2、t-ERK1/2、p-CREB、t-CREB、BDNF等蛋白的表达情况.结果 LXR激动剂TO901317处理后,I/R小鼠的海马齿状回DCX与BrdU阳性细胞的表达数目均增加(P＜0.01),认知功能得到了改善(P＜0.01),同时,海马ABCA1、p-ERK1/2、p-CREB、BDNF等蛋白表达水平也上调(P＜0.01).结论 肝X受体的激活促进了I/R小鼠海马齿状回颗粒下层神经干细胞的增殖和认知功能的改善,其机制可能与激活ERK1/2-CREB-BDNF信号通路,促进I/R小鼠海马DG区内源性神经发生有关.“,”Aim To investigate the effect of liver X receptor (LXR) activation on the proliferation of hippocampal neural stem cells in global cerebral ischemia/reperfusion (I/R) mice,and its mechanisms.Methods A total of 75 C57BL/6 mice were randomly divided into three groups,namely the sham operation group,the cerebral I/R group and the cerebral I/R with TO901317 treatment (I/R + TO90) group.The I/R mouse model was induced via the bilateral common carotid artery occlusion.HE staining was used to detect the pathological changes in hippocampal CA1 region.Immunohistochemistry was executed to detect hippocampus DCX + cells.Immunofluorescence of BrdU was implemented to detect the proliferation neural stem cell.Morris water maze test was used to assess spatial learning and memory in mice.Western blot was used to detect the expression of hippocampus LXRα,LXRβ,ABCA1,p-ERK1/2,t-ERK1/2,p-CREB,t-CREB,BDNF.Results LXR activation improved cognitive recovery(P ＜0.01),and induced the proliferation of neural stem cells (P ＜ 0.01) in I/R mice.The expressions of hippocampal ABCA1,p-ERK1/2,p-CREB,BDNF in I/R + TO90 group mice also increased (P ＜ 0.01).Conclusions LXR activation can induce the proliferation of hippocampal neural stem cells and facilitate cognitive recovery following global cerebral I/R in mice,which may be related to the activation of hippocampal ERK1/2-CREB-BDNF pathway and then promoting endogenous neurogenesis in the hippocampus DG region of I/R mice.