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

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 less than 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 less than 0.05) and increased amplitude (P less than 0.05), yielding an overall increased 24-h mean level (P less than 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 less than 0.05) of normal amplitude occurring at much more variable (P less than 0.01) interpulse intervals. Sleep-associated changes in LH pulsatility were absent. Responses to a 10-microgram bolus GnRH dose revealed blunted (P less than 0.05) FSH release in CA and augmented (P less than 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 less than 0.05) in both groups of athletes, and this elevation was extended through the day (0800-2000 h; P less than 0.001) and evening (2000-0200 h; P less than 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 less than 0.05 and P less than 0.01; delta cortisol, P less than 0.01 and P less than 0.01, respectively], but adrenal sensitivity (delta cortisol/delta ACTH ratio) was increased (P less than 0.05). The plasma ACTH and serum cortisol responses to meals also were blunted in the athletic groups (P less than 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)