成年大鼠脑缺血再灌注损伤后海马齿状回神经发生的实验研究

Dentate granule cell neurogenesis after global ischemia-reperfusion in the adult rat brain

目的 观察成年大鼠全脑缺血再灌注损伤对海马齿状回神经的影响 ,并探讨缺血性脑损伤后神经发生的相关机制。方法 采用 4支血管闭塞法建立大鼠全脑缺血模型 ,应用 5 溴脱氧尿核苷 (5 bromodeoxyuridine ,BrdU)标记分裂细胞、观察全脑缺血 再灌注损伤后 3、7、14、2 1d时大鼠海马齿状回神经前体细胞的增殖速度。并应用免疫荧光双标记法结合激光共聚焦显微镜观察确定新生细胞的分化特点。结果 全脑缺血 再灌注损伤后齿状回神经前体细胞增殖速度在 7～ 14d时明显增加 ,BrdU免疫阳性细胞数目与相应对照组比较 ,差异有显著性意义 (P <0 .0 1)。 2 1d时恢复正常水平。新生细胞大多迁移入颗粒细胞层 ,并分化为神经元。结论 缺血性脑损伤可增强海马齿状回神经发生 ,其机制可能与缺血引起的激素水平、神经递质。

Objectives To investigate the effects of global ischemia reperfusion on dentate granule cell neurogenesis in the adult rat brain,and to explore the possible mechanisms related to neurogenesis after cerebral ischemia.Methods Male mature Sprague Dawley rats were used to establish 4 vessel occlusion (4 VO) model.Using systemic bromodeoxyuridine(BrdU) to label dividing cells,the proliferation rate of neural precursor cells in the dentate gyrus at various time points after cerebral ischemia was observed.The double label immuno fluorescence with confocal microscopy was used to determine the newborn cells phenotype.Results Quantitative analysis of BrdU labeling revealed a significant increase in the proliferation rate of neural precursor cells in the dentate gyrus 7 days to 14 days after cerebral ischemia as compared with controls (P<0.01).The number of BrdU labeled cells in the dentate gyrus returned to baseline level by d 21.Most of the newborn cells migrated to the granule cell layer from the subgranular zone(SGZ),displayed the neuronal phenotype and developed morphological characteristics of differentiated dentate granule cells.Conclusions Neurogenesis in the dentate gyrus can be enhanced after global ischemia reperfusion.Its mechanisms may be related to the changes of hormones,neurotransmitters,neurotrophic factors and the micro circumstances of the dentate gyrus after ischemia.