Recombinant Human Erythropoietin Augments Neovascularization Responses In A Neonatal Model Of Premature Brain Damage By PI3K/Akt Pathway

Objective:1. To investigate that whether rh-EPO can activate PI3K/Akt pathway to promote the expression of CD34 and the number of CD34+cells in the surface of cells and then to augument neovascularization response in injured brain areas of a neonatal model of premature brain damage.2. To evaluate that whether rh-EPO can influence the expression of VEGFR2, levels of VEGF and Ang-1 genes through activating the PI3K/Akt pathway in the injured brain area of a neonatal model of premature brain damage.Methods:The postnatal day 5(PD5) rats were randomized into 5 groups as follows:(1) control group (?); (2) HI group (?); (3) HI+LY294002 group(?); (4) HI+rh-EPO group(IV); (5) HI+rh-EPO +LY294002 group(V).The content of phosphor-Akt in the right white matter of premature brains was tested 15,30,90 mins after the whole operation by western blot assays. The CD34 and VEGFR2 proteins were tested two days after the whole operation. At the same time, we count the numbers of CD34+cells by immunofluresence experiments in the two groups. The VEGF and Ang-1 mRNA levels were assessed by qRT-PCR two days after the whole operation.Results:1. The contents of p-Akt in the right white matter of premature brains tested 15 mins after the whole operation by western blot assays in group ?, ?, ?and ? were higher than in group I (P<0.05). P-Akt in group IV and V are higher than groupl, ?and ? (P<0.05).30 and 90 mins after the whole operation, the contents of p-Akt in group IV was significantly higher than the other four groups (P<0.05). GroupII was a little higher than group I(P<0.05). P-Akt in group IV in 15 min was higher than which in 30 min (P<0.05).2.2 days after the operation, the trends of CD34, VEGFR2, VEGF and Ang-1 which were tested by western blot assay, immunofluresence experiments and qRT-PCR were constant with p-Akt.Conclusions:1. Rh-EPO increased the p-Akt in injuried brain gradually in 30 minutes after brain injury.2. Hypoxic-ischemic damage can slightly increase the expressions of VEGFR2, CD34, number of CD34+cells, VEGF and Ang-1 gene levels through activating the PI3K/Akt pathway in the injured brain area of a neonatal rat model of premature brain damage.3. Rh-EPO can increase the expressions of VEGFR2, CD34, number of CD34+cells, VEGF and Ang-1 gene levels through activating the PI3K/Akt pathway in the injured brain area of a neonatal rat model of premature brain damage and then to promote the neovascularization in the damaged areas of premature brains. The functions of rh-EPO were stronger than hypoxic-ischemic damage.