Abstract: 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 (P0.05), with the highest expression level at day 20 (P0.01). TUNEL positive cells also significantly increased at day 6 in the 20min hypoxia-treaded 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 repai

Key words: Hypoxia, Neurogenic differentiation factor, Neurogenesis, Immunofluorescence, TUNEL, Immunohistochemistry, Rat