Effect of Ethylene Diurea on Oxygen-induced Ischemic Retinopathy in the Neonatal Rat

This study investigated the effect of N-[2- (2-oxo-1-imidazolidinyl) ethyl]-N-phenylurea (ethylene diurea, EDU) on oxygen-induced ischemic retinopathy (OIR) in a neonatal rat model. OIR was induced by maintaining daily cycles of 80% oxygen (20.5h), ambient air (0.5h), and a progressive return to 80% oxygen (3h) for 12 days (postnatal day: P12). The rats were treated intraperitoneally with EDU (30mg/kg body weight) or distilled water (DW) from P6 to P17. At P18, the percentage of avascular areas in the total retinal area (%AVA) was measured, and retinal neovascularization (NV) was scored in ADPase-stained retinas. Retinal superoxide dismutase (SOD) activity in the retina was also determined by a chemiluminescence method. The mean %AVA in the EDU-treated group (9.3 ± 1.7%, n = 16) was lower than in the DW group (18.2 ± 4.7%, n = 17). EDU did not significantly affect NV, but significantly increased SOD activity (1.36 ± 0.13 units/mg protein, n = 4) compared to DW treatment (1.04 ± 0.01 units/mg protein, n = 4, P = 0.032) at P18. These results suggest that EDU treatment decreased the %AVA, accompanied by an increase in normal retinal vascular growth and/or a decrease in vessel proliferation. The increased SOD activity observed in the present study is likely to involve the EDU-mediated effects.