Alterations in the Hypothalamic-Pituitary-Ovarian and the Hypothalamic-Pituitary-Adrenal Axes in Athletic Women*

Publisher Website
Google Scholar
Abstract
The functional integrity of the hypothalamic-pituitary-ovarian and hypothalamic-pituitary-adrenal axes was assessed by determining pulsatile LH, ACTH, and cortisol secretion during the early follicular phase in athletic women with regular menstrual cycles (CA; n = 9), athletic women with amenorrhea (AA; n = 9), and regularly cyclic sedentary women (CS; n = 8). The CA and AA women were not significantly different in body composition, exercise training, psychometric tests, or dietary consumption. The CA women had shorter luteal phases (P < 0.05) and lower urinary excretion of pregnanediol glucuronide than the CS women. In the AA women, urinary estrone glucuronide, pregnanediol glucuronide, and LH excretion were low throughout a 30-day period. The CA women had a 24-h pattern of pulsatile LH secretion characterized by reduced frequency (P < 0.05) and increased amplitude (P < 0.05), yielding an overall increased 24-h mean level (P < 0.05), but interpulse intervals similar to those in the CS women. During sleep, LH pulse frequency slowed in the CS and CA women, while pulse amplitude increased and the mean serum LH level decreased in both groups. The AA women had even fewer pulses (P < 0.05) of normal amplitude occurring at much more variable (P < 0.01) interpulse intervals. Sleep-associated changes in LH pulsatility were absent. Responses to a 10-.mu.g bolus GnRH dose revealed blunted (P < 0.05) FSH release in CA and augmented (P < 0.05) LH release in AA women. The groups did not differ in any 24-h ACTH pulse pattern parameter or in cortisol pulse frequencies. Yet, early morning (0200-0800 h) serum cortisol levels were higher (P < 0.05) in both groups of athletes, and this elevation was extended through the day (0800-2000 h; P < 0.001) and evening (2000-0200 h; P < 0.05) in the AA women. The plasma ACTH and serum cortisol responses to bolus human CRH administration were blunted in the CA and AA women [change from baseline (.DELTA. in ACTH, P < 0.05 and P < 0.01; .DELTA. cortisol, P < 0.01 and P < 0.01, respectively], but adrenal sensitivity (.DELTA. cortisol/.DELTA. ACTH ratio) was increased (P < 0.05). The plasma ACTH and serum cortisol repsonses to meals also were blunted in the athletic groups (P < 0.05). These results indicate that the degree to which the hypothalamic-pituitary-adrenal axis is disturbed in cyclic and amenorrheic athletes is associated, perhaps causally, with their hypothalamic-pituitary-ovarian axis abnormalities.