Expression of Brain-Derived Erythropoietin in Hippocampal CA1 Region after Hypoxic-Ischemic Brain Damage in Neonatal Rat

Objective To observe the expression of brain-derived erythropoietin (EPO) in hippocampus after hypoxic-ischemic brain damage(HIBD)in neonatal rats,and to explore the mechanism of endogenous neuro-protective factors on enhanced neurogenesis in hippocampus after HIBD.Methods SD rats,7 days of age,were randomly divided into 4 groups:control (C) group,hypoxia (H) group,ischemia(I) group and hypoxic-ischemic(HI) group.Histological assessment of each group was performed 1 h,6 h,16 h,1 d,3 d,and 7 d after HIBD.EPO-immunoreactivity at the cornu ammonis subfield 1 area (CA1) was determined with immunohistochemical staining at each time point.Results There were no differences in the expression of brain-derived EPO at each time point in the C group(F=1.185 P0.1),and there were significant differences in the other groups[F(H)=33.57,F(I)=133.6,F(HI)=69.75 Pa0.001,respectively].The expression of brain-derived EPO was detected 1 h after HIBD,reaching a peak 16 h after HIBD,and decreased thereafter,and the statistical difference was significant(t=13.08 P0.001).There were significant differences between H,I,HI and C groups(q=32.06,23.84,47.12 Pa0.001).Conclusions The production of endogenous neuro-protective EPO increases after HIBD in neonates.The overexpression of brain-derived EPO occurs within 16 h after HIBD,just preceding peak neurogenesis.Hypoxia-induced overexpression of EPO is one of the endogenous factors that is involved in neurogenesis in the neonatal hippocampus after HIBD.