ObjectiveTo investigate the effects of leptin on the oxidative damage in human retinal pigment epithelial (RPE) cells. MethodsHuman RPE cells (ARPE-19) were cultured in vitro, and randomly divided into control group and insulin resistance group. RPE cells were treated with 0, 10, 100 ng/mL leptin for 24, 48, 72 hours respectively. Then the levels of reactive oxygen species (ROS) expression in RPE cells were detected by 2', 7'-dichlorofluorescin-diacetate (DCFH-DA), and the levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG) expression in RPE cells were observed by immunocytochemistry (ICC), and the levels of human 8-oxoguanine DNA glycosylase l (hOGG1) expression in lysate were measured by Western blot. ResultsAfter 24, 48, 72 hours, the level of ROS (Control group:F=37.136, 37.178, 49.634; P < 0.05. Insulin resistance group:F=9.822, 28.881, 71.150;P < 0.05), 8-OHdG (Control group:F=88.643, 390.920, 1039.276;P < 0.05.Insulin resistance group:F=273.311, 299.155, 82.237;P < 0.05) and hOGGl (Control group:F=470.062, 1073.113, 295.456;P < 0.05. Insulin resistance group:F=240.032, 592.389, 527.760;P < 0.05) expression increased significantly with the increase of leptin concentration in control group and insulin resistance group. Under the same leptin concentration, the level of 8-OHdG has a trend that it was higher in the insulin resistance group than the control group. After 24 hours, the difference of hOGGl expression between control group and insulin resistance group was not significant (F=23.392, P > 0.05). After 72 hours, the level of hOGGl expression was significantly higher in the insulin resistance group than the control group (F=129.394, P < 0.05). The level of hOGGl expression was significantly higher at 48 hours than that at 24 hours and 72 hours (P < 0.05). ConclusionLeptin could induce the oxidative damage of RPE cells in normal and insulin resistance status. With the increase of leptin concentration and time extended, the degree of oxidative damage and its repair were both increased. The degree of oxidative repair increased with the increase of leptin concentration, but decreased with time extended.