短暂缺氧对新生鼠脑细胞凋亡和神经再生的影响

Effects of transient hypoxia on apoptosis and neurogenesis in the newborn rat brain

目的探讨短暂缺氧对新生鼠脑神经源性分化因子(NeuroD)表达以及细胞凋亡和神经再生的影响。方法新生10～24h的SD大鼠短暂置于100%氮气环境中,建立出生窒息模型。96只新生大鼠随机分为对照组、缺氧20min组,其中1个亚组分3个时间点(13、20、27d)取材,采用免疫荧光法检测NeuroD、免疫组织化学法检测5-溴脱氧尿嘧啶核苷(BrdU)表达的变化。另一亚组分2个时间点(6、20d)取材,原位缺口末端标记法(TUNEL)检测细胞凋亡。结果免疫荧光/免疫组织化学结果显示,缺氧20min组13、27d NeuroD和BrdU在海马CA1区/室下区的表达量均高于对照组(P<0.05),且在20d表达量最高(P<0.01)。TUNEL法检测出缺氧20min后6d在海马CA1区凋亡细胞阳性率明显高于对照组(P<0.01),而20d凋亡细胞阳性率与对照组比较差异无统计学意义。结论缺氧引起迟发性细胞凋亡,导致神经元缺失,可能诱导细胞增殖、分化,触发神经发生,对受损的脑组织进行代偿性修复和神经功能重建。

Objective To investigate effects of transient hypoxia on the expression level of neurogenic differentiation factor （NeuroD） , apoptosis and neurogenesis in the rat brain. Methods The model was established as previously described by Grojean, newborn rats were transiently exposed to 100% N2. Ninety-six animals were randomly divided into normal control group and 20min hypoxia-treated group. Rats were sacrificed at day 13, 20 and 27 post-hypoxia, and the expression levels of NeuroD and BrdU in the brain were analyzed by immunofluorescence staining and immunohistochemistry. Alternatively, the rats were sacrificed at day 6 and 20 post-hypoxia, and apoptosis in the brain was analysed with TUNEL staining. Results Immunofluorescence/immunohistochemisty analysis showed that the expression of NeuroD and BrdU significantly increased at day 13 and 27 in the 20min hypoxia-treaded group compared to that in the control group （ P 〈 0.05 ） , with the highest expression level at day 20 （P 〈 0. 01 ）. TUNEL positive cells also significantly increased at day 6 in the 20min hypoxiatreaded group, while no difference was seen between the hypoxia-treated and the control group at day 20. Conclusion The transient neuronal loss induced by birth hypoxia may lead to cell proliferation, neuron differentiation and also may trigger neurogenesis, which may in turn participate in brain repair and functional restoration.