RESPONSES OF CATECHOLESTROGEN METABOLISM TO ACUTE GRADED-EXERCISE IN NORMAL MENSTRUATING WOMEN BEFORE AND AFTER TRAINING

It has been hypothesized that exercise-related hypo-estrogenemia occur s as a consequence of increased competition of catecholestrogens (CE) for catechol-O-methyltransferase (COMT). This may result in higher nor epinephrine (NE) concentrations, which could interfere with normal gon adotropin pulsatility. The present study investigates the effects of t raining on CE responses to acute exercise stress. Nine untrained eumen orrheic women (mean percentage of body fat +/-SD: 24.8 +/- 3.1%) volun teered for an intensive 5-day training program. Resting, submaximal, a nd maximal (t(max)) exercise plasma CE, estrogen, and catecholamine re sponses were determined pre-and post training in both the follicular ( FPh) and luteal phase (LPh). Acute exercise stress increased total pri macy estrogens (E) but had little effect on total 2-hydroxyestrogens ( 2-OHE) and 2-hydroxyestrogen-monomethylethers (2-MeOE) (= O-methylated CE after competition for catechol-O-methyltransferase). This pattern was not significantly changed by training. However, posttraining LPh m ean (+/- SE) plasma E, 2-OHE, and 2-MeOE concentrations were sig nific antly lower (P < 0.05) at each exercise intensity (for 2-OHE: 332 +/- 47 vs. 422 +/- 57 pg/mL at t(max); for 2-MeOE: 317 +/- 26 vs. 354 +/- 34 pg/mL at t(max)). Training produced opposite effects on 2-OHE:E rat ios (an estimation of CE formation) during acute exercise in the FPh ( reduction) and LPh (increase). The 2-MeOE:2-OHE ratio (an estimation o f CE activity) showed significantly higher values at t(max) in both me nstrual phases after training (FPh: + 11%; LPh: +23%; P < 0.05). After training, NE values were significantly higher (P < 0.05). The major f indings of this study were that: training lowers absolute concentratio ns of plasma estrogens and CE; the acute exercise challenge altered pl asma estrogens but had little effect on CE; estimation of the formatio n and activity of CE suggests that formation and O-methylation of CE p roportionately increases. These findings may be of importance for NE-m ediated effects on gonadotropin release.