Changes in the erythrocyte antioxidant enzyme system during transdermal estradiol therapy for secondary amenorrhea

Twenty-two hypothalamic amenorrheic patients, who were non-smokers and of normal weight, received replacement therapy for 1 month with transdermal patches containing 8 mg estradiol. No other drugs were prescribed or taken during the study. Before treatment (time 0) and 1 month after its start, blood samples were taken for assay of plasma estradiol levels, the erythrocyte antioxidant enzyme activities of superoxide dismutase, catalase, glutathione peroxidase (GSH-Px), and an age-dependent erythrocyte enzyme activity, pyruvate kinase. Plasma malondialdehyde levels, as an index of lipoperoxidation products, were also detected. The results showed no significant variations in superoxide dismutase, catalase, pyruvate kinase erythrocyte enzyme activities or plasma malondialdehyde levels. A significant increase in plasma estradiol levels (time 0, 17.33 +/- 4.12 pg/ml; 1 month, 81.25 +/- 10.45 pg/ml; means +/- SD; p < 0.0001) and in GSH-Px erythrocyte activity (time 0, 11.97 +/- 2.31 IU/g hemoglobin; 1 month, 16.88 +/- 4.38 IU/g hemoglobin; p < 0.004) was found. Plasma estradiol levels correlated significantly with GSH-Px erythrocyte activity 1 month after therapy was begun (r = 0.776, p < 0.003). We suggest that estrogens restored to physiological plasma levels, stimulate erythrocyte antioxidant GSH-Px activity, improving the antioxidant power of amenorrheic patients.