Effects of green tea fractions on oxygen-induced retinal neovascularization in the neonatal rat

Abstract

This study aimed to investigate the preventive effects of green tea fractions (GTFs) on rat model of oxygen-induced retinopathy (OIR). Neonatal Sprague-Dawley rats were exposed to daily cycles of 80% oxygen (20.5 h), ambient air (0.5 h), and progressive return to 80% oxygen (3 h) until postnatal day 12 (P12), then the rats were placed in ambient air until P18. The green tea was fractionated by DM-A50, DM-W, M-B, and M-W. The rats were treated once daily from P6 to P17 by gastric gavage of GTFs (0.05 or 0.01 g/ml) or distilled water (DW) at 50 microl/10 g body weight. On P18, the rats were sacrificed and the retinal samples were collected. The retinal neovascularization (NV) was scored and avascular areas (AVAs) were measured as a % of total retinal area (%AVAs) in ADPase stained retinas. The NV scores in 0.01 g/ml M-W were significantly lower than those in DW. The %AVAs in 0.05 g/ml DM-A50 and in 0.05 g/ml and 0.01 g/ml M-W were significantly lower than those in DW. There were less catechins, and less caffeine in M-W fraction compared with other GTFs, suggesting components of green tea except for catechins and caffeine might suppress the neovascularization in rat model of OIR.

Keywords: green tea; neovascularization; oxygen-induced retinopathy; retinopathy of prematurity.

Fig. 1

Extraction and fractionation of green tea

Fig. 2

Body weight of the oxygen-exposed rats on P18. Data represents mean ± SE. The body weights on P18 of DM-A50, M-B and M-W in 0.05 g/ml-treated group and DM-A50 in 0.01 g/ml-treated group were significantly lower than these of DW (*p<0.05, n = 5–31).

Fig. 3

The typical samples of flatmounted ADPase stained retinas in OIR. (A) 0.05 g/ml DM-A50 treated group. NV score is 6 %AVAs is 10.62%. (B) 0.05 g/ml DM-W treated group. NV score is 3 %AVAs is 16.39%. (C) 0.05 g/ml M-B treated group. NV score is 7 %AVAs is 26.18%. (D) 0.05 g/ml M-W treated group. NV score is 5 %AVAs is 23.28%. (E) DW group. NV score is 13 %AVAs is 32.05%.

Fig. 4

NV score in the oxygen-exposed rat retinas. In 0.01 g/ml M-W treated group, NV score is significantly lower than DW. The data represent mean ± SE (*p<0.05, n = 5–31).

Fig. 5

%AVAs in the oxygen-exposed rat retinas. In 0.05 g/ml DM-A50 and 0.05 g/ml and 0.01 g/ml M-W treated groups the %AVAs are significantly lower than those in DW. The data represent mean ± SE (p<0.05, n = 5–31).