Estrogen as an antioxdant in the lens

Summary Female gender is a known risk factor for age‐related cataract, although the explanation for this is still largely unknown. We have demonstrated that physiologic concentrations of 17b‐estradiol (E2) protect cultured human lens epithelial cells (HLECs) from oxidative stress induced by H2O2, as evident by decreased production of reactive oxygen species (ROS) and a stabilization of the mitochondrial membrane potential. Total superoxide dismutase (SOD) activity was increased by these concentrations of E2 but no change in gene or protein expression of SOD was seen. In cataract patients and controls, a significant correlation between higher age and decreasing serum levels of E2 was found but no correlation between serum levels of E2 and SOD was demonstrated. Men exhibited higher E2 levels compared to postmenopausal women. To conclude, estrogen seems to exert antioxidative effects on human lens cells, possibly by affecting SOD activity, which may explain the difference in risk of cataract between genders. The finding that men have higher levels of E2 than postmenopausal women further supports the hypothesis that it is the decline in estrogen at menopause that causes the higher risk of cataract in women.