Influence of hormone replacement therapy on blood antioxidant enzymes in menopausal women

Background: Natural loss of estrogen occurring in menopausal process may contribute to various health problems many of them possibly related to oxidative stress. Hormone replacement therapy (HRT) is the most common treatment to attenuate menopausal disturbances. This study was aimed at evaluating the influence of HRT on the activity of antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; and glutathione peroxidase, GPx) and lipid peroxidation (thiobarbituric acid reactive substances, TBARS) in menopausal women. Methods: Blood antioxidant enzyme activities were determined in premenopausal (n = 18) and in postmenopausal healthy women without (n =21) or with (n = 19) HRT (mean ages: 47, 59, and 57 years, respectively). Results: TBARS, CAT, and GPx activity were not significantly different among the groups of study. However, SOD activity was significantly lower in postmenopausal women without HRT (0.68 +/- 0.04 U/mg Hb) when compared both to premenopausal women (0.91 +/- 0.04 U/mg Hb) and to postmenopausal women with HRT (0.89 +/- 0.07 U/mg Hb). SOD activity was positively correlated to the duration of HRT in the postmenopausal groups (r = 0.33, p < 0.05). Conclusions: HRT antagonizes the decrease of SOD activity that occurs after menopause, suggesting that HRT may play a beneficial role in the protection against oxidative stress. (c) 2006 Elsevier B.V. All rights reserved.