Effects of a training program on resting plasma 2-hydroxycatecholestrogen levels in eumenorrheic women

Abstract

De Crée, Carl, Peter Ball, Bärbel Seidlitz, Gerrit Van Kranenburg, Peter Geurten, and Hans A. Keizer.Effects of a training program on resting plasma 2-hydroxycatecholestrogen levels in eumenorrheic women. J. Appl. Physiol. 83(5): 1551–1556, 1997.—Catecholestrogens (CE) represent a major metabolic pathway in estrogen metabolism. Previous information on CE and training is limited to two cross-sectional studies that did not involve standardized training. Our purpose, by means of a prospective design, was to evaluate the effects of a brief, exhaustive training program on resting plasma concentrations of 2-hydroxy CE. The experimental design spanned two menstrual cycles: a control cycle and a training cycle. The subjects were nine previously untrained, eumenorrheic women [body fat: 24.8 ± 1.0 (SE) %]. Data were collected during the follicular (FPh) and the luteal phases (LPh). Posttraining FPh and LPh tests were held the day after the last day of a 5-day period of training on a cycle ergometer. Total 2-hydroxyestrogens (2-OHE) averaged 200 ± 29 pg/ml during the FPh and 420 ± 54 pg/ml during the LPh ( P < 0.05). Levels of total 2-methoxyestrogens (2-MeOE) were 237 ± 32 pg/ml during the FPh and 339 ± 26 pg/ml during the LPh ( P< 0.05). After training, although the plasma levels of 2-OHE significantly decreased (−21%; P < 0.05) during the LPh, the actual CE formation (as estimated from the 2-OHE-to-total estrogens ratio) increased (+29%; P < 0.05). CE activity, as expressed by the 2-MeOE-to-2-OHE ratio, showed significantly higher values in both phases (FPh, +14%; LPh, +13%; P < 0.05). At the same time, resting levels of norepinephrine (NE) were increased by 42% ( P < 0.05). CE strongly inhibit biological decomposition of NE by catechol- O-methyltransferase (COMT). Results of the present study suggest that, in response to training, CE are increasingly competing with the enzyme COMT, thus preventing premature NE deactivation.