Time-dependent Expression of PEDF and VEGF in Blood Serum and Retina of Rats with Oxygen-induced Retinopathy

The effects of the balance changes of pigment epithelium growth factor(PEDF) and vascular endothelial growth factor(VEGF) in whole-body and retinal tissue on rats with oxygen-induced retinopathy were investigated. Forty-eight neonatal SD rats at the age of 7 days were randomly divided into 4 groups. The neonatal rats in experimental groups were exposed to 75% to 80% oxygen for 5 days and then to normal air, and those in control groups were kept feeding in normal air. At the age of 17 and 22 days, all the neonatal rats received retina angiography with FITC-dextran and the pathological changes of retinal vessels and perfusion were observed. HE staining of the tissue section and the number counting of endothelial cells extending beyond the inner limiting membrane were performed to evaluate the endothelial proliferation. Immunohistochemistry was applied to detect the expression of PEDF and VEGF in retinal tissue, and ELISA to detect their expression in serum. A hypoxic-ischemic proliferation of retina and more endothelial cells extending beyond the inner limiting membrane were found in the neonatal rats in both experimental groups of 17-day old and 22-day old as compared with those in control group with the difference being statistically significant(P<0.01). VEGF staining of the rats in the 17-day old experimental group was significantly stronger, with an increasing positive rate, than that of the rats in the 17-day old control group(P<0.01). PEDF staining of the rats of 22 days old was weaker than that of the rats of 17 days old in the experimental groups(P<0.01). There was no significant difference in serum VEGF concentration among all groups(P>0.05). The serum PEDF concentration in the rats of 17 days old in experimental group was decreased significantly as compared with that in the rats of 17 days old in control group(P<0.01), and in experimental groups, the serum PEDF concentration of the rats of 22 days old was increased as compared with that of the rats of 17 days old(P<0.01). In conclusion, the obviously decreased serum PEDF concentration and the abnormal enhanced expression of VEGF density in local retinal tissue broke down the balance of PEDF/VEGF in whole-body or local tissues, which might play an important role in retinal vascular proliferation.