Experimental Study On EGCG In Association With VitC In Hibition Of Hydrogen Peroxide Induced Cataract Formation Of Rabbit's Lens

Objective: To observe the inhibitory effect of EGCG on hydrogen peroxide inducing the apoptosis of rabbits'lenses. To explore the validity of EGCG in association with VitC on the treatment of hydrogen peroxide induced cataract formation.Methods: Cultured normal rabbits'lenses in vitro were randomly divided into 6 groups: the control group (A),the group treated by hydrogen peroxide(B) ,the group treated by hydrogen peroxide and EGCG(10mmol/L,20mmol/L)(C1,C2), the group treated by hydrogen peroxide and EGCG(10mmol/L,20mmol/L)in association with VitC(D1,D2). The transparence and apoptosis ratio of lenses on the time points of 24,48,72h hours were determined image analysis and flow cytometry. At the end of the incubation period, the lenses were examined for biochemical parameters such as total antioxidiation ability(T-AOC),malondialdehyde (MDA) and superoxide dismutase (SOD) by spectrophoto metrically. At the same time,the histological changes of all lenses were examined by electron microsopies and verified the occurrence of programmed cell death and the expression of bcl--2 was detected by the immunohistochemical ,as well as by terminal deoxyribonucleotide transferase-mediate dUTP nick end labeling(TUNEL)detection,we examined the effect of EGCG on the number of H202-induced rabbit'lenses epithelial cell apoptosis and the related comparisons and statistic analysis were carried out.Result: The transparence of the group treated by hydrogen peroxide and EGCG and the group treated by hydrogen peroxide and EGCG in association with VitC are higher than that of the group treated by hydrogen peroxide and lower than that of the control group.The differences among groups were statistically significant (P<0.05). 2,The level of MDA was increased and levels of T-AOC and T-SOD were decreased significantly in High Glucose group compared with those of them in control group (P<0.05).The level of MDA was significantlydecreased but the levels of other indexes were increased in EGCG groups compared with those of them in hydrogen peroxide group.3,The opacity of the lenses in every group was evaluated. The longer incubated with hydrogen treatment, the more the taper peroxide active expression of Bcl-2 in lens epithelial cells were found, the latter was positively correlate with opaque degree of lens and to a certain extent EGCG had a dose-dependent action in enhancement the active expression of Bcl-2 in rabbits'lens epithelial cells and relieve opacity of lens. 4,The TUNEL method revealed that the apoptosis rate for LECs in H2O2 group was apparently higher than that for the control group(p<0.05);There was a significant difference between the EGCG in association with tocopherol group and the H2O2 group(p< 0.05).Conclusion: These experiments confirmed that:the antioxidant-EGCG can evidently inhibit LEC apoptosis which may be the cellular and molecular mechanisms of EGCG preventing and delaying the development of the cataract .