Serum lipid peroxide levels and erythrocyte glutathione peroxidase and superoxide dismutase activity in premenopausal and postmenopausal women.

Free radical reactions are involved in processes connected with aging. Estradiol acts as antioxidant and free radical scavenger, but the mechanism of this action remains unknown. Estradiol has a hydroxyphenolic structure and may donate hydrogen atoms to lipid peroxyradicals to terminate chain reactions. There are a few reports concerning the influence of estradiol on natural antioxidant enzyme activity, such as superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT). The aim of this study was to estimate the relationship between the levels of estradiol and lipid peroxide (LPO), a marker of membrane lipid peroxidation, and the correlation between estradiol and erythrocyte SOD and GSH-Px activity. The study included 13 premenopausal and 13 postmenopausal healthy women. Serum levels of estradiol, follicle-stimulating hormone (FSH) and LPO, and erythrocyte SOD and GSH-Px activity were estimated in all subjects. Premenopausal women revealed significantly higher estradiol levels and lower LPO concentrations, as well as significantly higher GSH-Px activity than the postmenopausal group. SOD activity did not differ between the two groups. There was a negative correlation between serum estradiol and LPO levels as well as a positive correlation between estradiol and GSH-Px activity. These results support the hypothesis that estradiol exerts its antioxidant action not only through its chemical structure but probably also through its influence on natural cellular antioxidant enzyme activity.