CIRCADIAN VARIATIONS IN PLASMA ACTH, CORTISOL AND BETA-ENDORPHIN LEVELS IN NORMAL-WEIGHT BULIMIC WOMEN

In order to establish possible alterations in the secretory patterns o f adrenocorticotropic hormone (ACTH), cortisol and/or beta-endorphin i n bulimia nervosa, the circadian fluctuations of these hormones were e valuated in blood samples taken at 1-hour intervals over 24 h. Eleven bulimic women with normal body weight and 8 weight- and age-matched no rmal controls were tested during the follicular phase (days 6-8) of no rmal menstrual cycles. All women were hospitalized for bulimia or for checkup examinations and were tested 3 days after hospital admission. Both normal and bulimic women showed maximal ACTH, cortisol and beta-e ndorphin levels at 08.00 h, with minimal ACTH and beta-endorphin level s at midnight and cortisol levels at 02.00 h. The general temporal str ucture of all hormonal secretions coincided in the two groups. However , whereas all measured ACTH/cortisol levels were quantitatively simila r in the two groups, plasma beta-endorphin concentrations were signifi cantly higher in bulimic than in control subjects at all examined time points. The enhancement in the overall 24-hour beta-endorphin secreti on suggests the presence of an increased opioid tonus in bulimic women , which might play a role in the pathophysiology of the eating disorde r.