Study on the proliferation of endogenous neural stem cells in hippocampus of newborn SD rats with hypoxic-ischemic brain damage and the regulation by estrogen

Objective To investigate the expression levels of endogenous neural stem cells(NSCs) marker-nestin in SD rat HIBD model and the control groups.To study the influence of 17βestradiol(17β-E2)on the proliferation of endogenous NSCs in hippocampus.Methods 7-day-old SD newborn rats were randomly divided into HIBD and the control groups(n=8).The rats were sacrificed at different given time points at 12h、1、3、7、14d after HIBD respectively.The expression levels of nestin were determined by using immunofluorescence.For estrogen interventional experiment,3d after HIBD model was chosen as the observing point.17β-estradiol(E2) with different concentrations(10μg/(kg·d)、100μg/(kg·d)、1000μg/(kg·d)were daily injected into the rat's neck subcutaneously for a total of 3 days.Bromode-oxyuridine(Brdu,50mg/kg,twice a day)was intraperitoneally administered to all the rats for 3 days.Cell proliferation(Brdu-positive nuclei)was observed by immunofluorescence staining.Results Nestin expression increased at HIBD 1d,reached a peak at HIBD 3d,decreased gradually at HIBD 7d compared with the control group(P0.05) in hippocampus.Brdu-positive cells increased accordingly with the increase of estrogen's concentration.Brdu-positive cells reached a peak in high E2 group(H3).Brdu-positive cells were significantly different among each group(P0.05).Conclusion HIBD can activate NSCs,nestin expression in hippocampus reached a peak at HIBD 3d and decreased gradually then.17β-E2 has some protective effects on HIBD of neonatal rats.Estrogen could increase the number of Brdupositive cells in hippocampus.