Inhibition of Oxygen-induced Retinal Neovascularization in the Neonatal Rat by Green Tea Extract

Abstract

To investigate the effect of green tea extract (GTE) on oxygen-induced neovascularization (NV) in neonatal rat model, NV was induced by maintaining neonatal rats in 80% oxygen on a cycle of 23.5h oxygen/0.5h room air until postnatal day 12 (P12), when the rats were placed in room air. The control rats were maintained in room air. From P6 to P17, rats were treated once daily by oral administration of saline (50μl/10g body weight) that contained 25% GTE, 12.5% GTE, or nothing. On P18, the rats were sacrificed and the retinal samples were collected. Retinal NV was scored and avascular areas (AVAs) were measured in ADPase stained retinas. The retinal vascular endothelial cell growth factor (VEGF) contents were measured with immunoassay kit, and matrix metalloproteinase-2 (MMP-2) activity was determined by gelatin zymography. GTE (25%) treatment suppressed NV and slightly increased AVAs in oxygen-induced NV model compared with the control. VEGF contents in retina significantly increased on P13 and P15, but GTE treatment did not prevent the increase of VEGF contents. Oxygen-induced increases in MMP-2 activity on P13 and P15 were suppressed by GTE treatment. These results suggest that GTE suppressed oxygen-induced NV in the neonatal rat, possibly through inhibition of MMP-2 activity. It also suggests that orally administered green tea has the potential to inhibit neovascular disease.