BACKGROUND

Vigorous physical activity and subsequent depressed ovarian hormone secretion resulting in anovulatory menstrual cycles can affect erythrocyte antioxidant system in premenopausal women and contribute to attenuated protection against oxidative stress.

METHODS

A total of 17 regularly menstruating women participated in the study. Prospective subjects monitored their basal body temperature (BBT) for 3 months prior to the study. Plasma progesterone concentration was assayed between the 7th and 9th day and again between the 22nd and 25th day of the menstrual cycle and made possible the classification of participants as either ovulating or non-ovulating. Plasma 17-beta-estradiol concentration was determined on the same menstrual cycle days as progesterone. Plasma thiobarbituric acid-reacting substances (TBARS) served as an index of plasma lipid peroxidation. Whole blood-reduced glutathione (GSH) concentration and glutathione peroxidase (GSH-PX) activity and erythrocyte catalase (CAT), superoxide dismutase and glutathione reductase (GSH-RX) represented red cells antioxidants.

RESULTS

In non-ovulating women, the lack of progesterone peak between the 22nd and 25th day of the menstrual cycle was demonstrated. In addition, markedly lower (P<0.008) plasma 17-beta-estradiol concentrations in non-ovulating females than in ovulating ones in the follicular phase was noted. In the luteal phase, plasma 17-beta-estradiol levels in non-ovulating subjects tended to be lower (P<0.06) than in ovulating counterparts. Mean concentrations of plasma thiobarbituric-reacting substances and blood-reduced glutathione and mean activities of glutathione reductase, glutathione peroxidase and catalase did not differ significantly in ovulating and non-ovulating women. In non-ovulating women, both between the 7th and 9th day and the 22nd and 25th day of the menstrual cycle, erythrocyte superoxide dismutase (SOD) activity was higher (P<0.02) than in their ovulating counterparts. In ovulating subjects, significant and inverse correlation was demonstrated between circulating estradiol and SOD activity in collected data from both follicular and luteal phases.

CONCLUSIONS

Current results indicate that persistent ovarian hormone disturbances in regularly menstruating women, and resultant anovulation did not affect plasma lipid peroxidation and GSH-dependent erythrocyte antioxidant defense. However, lower plasma estradiol concentrations resulted in attenuated erythrocyte SOD inhibition and elevated enzyme activity. The mechanism of inhibitory estradiol action on erythrocyte SOD activity as well as the importance of this effect for antioxidant protection merits further studies.