Age related cell proliferation and differentiation after cerebral hypoxia ischemia

Aim:To investigate the effect of the hypoxia-ischemia brain injury on the cytogenesis with the different age.Methods:C57/BL6 mice at postnatal day 9 and 21 were induced hypoxia ischemia(HI) by ligation of left carotid artery and inhalation of 7.7% oxygen for 35 min(for P9)/30 min(for P21).Bromodeoxyuridine(BrdU) was injected into the brains in different development periods once a day for 7 d.The brains were retrieved 4 weeks after the last BrdU injection.The mice with corresponding age were choosen for contnol group.Immunohistochemical and immunofluorescent studies were carried out for detecting cell proliferation(BrdU) and cell differentiation,respectively.Results:The cell proliferation decreased significantly with brain development.HI insult increased BrdU positive cells significantly in the ipsilateral cortex and striatum of the immature brain(P9).In the juvenile(P21),large amount of new born cells was only seen in the ipsilateral striatum.A small portion of BrdU and NeuN double labeled cells could be detected in the cortex and striatum of P9 and only in striatum of P21.The majority of BrdU labeled cells were neuroglia.HI insult stimulated to produce a large number of neuroglia cells in the ipsilateral cortex and stritum of P9 group.In the juvenile striatum,Iba1 and S100β positive cells increased 50 and 8 folds after HI,but the number of APC positive cells was no significant change.Conclusion:Moderate HI induced cell proliferation and survive,cell proliferation and differentiation were brain regions and age related.