Abstract:

BACKGROUND: Oxygen plays an important role in premature retinal neovascularization, but its scope of oxygen and the specific mechanism of retinopathy are not clear.
OBJECTIVE: To study the effects of different concentrations of oxygen on neovascularization in oxygen-induced retinopathy of newborn rats.
METHODS: Forty newly born rats were divided into four groups: air group (10 rats) was raised in air room. Fluctuation group 1, 2, 3 (10 rats) was exposed to cycles of 50%-20%, 40%-10%, 50%-10% for 14 days, respectively. Retinas were dissected and stained by adenosine-diphosphatase (ADPase) histochemistry for assessment of intraretinal vascular development and preretinal angiogenic vessel growth. Expressions of vascular endothelial growth factor (VEGF) were studied by Western-blot.
RESULTS AND CONCLUSION: Retina flat-mounts presented increasing neovascular tufts, severity of retinal neovascularization and the number of vascular nuclei extending from the internal limiting membrane into the vitreous, as well as VEGF-expression in fluctuation group 2 and fluctuation group 3. There were no obviously neovascularization in the air and fluctuation 1 groups. This study suggested that a small change in blood oxygen profile could trigger a disproportionate increase in subsequent neovascularization, accompanied by changes of retinal VEGF level. VEGF promote retinal neovascularization. The over-expression of VEGF plays a synergistic role during the formation of neovascularization. Partial pressure of inspiratory oxygen was positively correlated with the retinopathy. Hypoxia may be more important for retinal neovascularization on the occurrence of retinopathy than hyperoxia.