Are disturbances in opioid and adrenergic systems involved in the hormonal dysfunction of anorexia nervosa?

Opioid peptides and catecholamines play an important role in the control of appetite, behaviour and hormonal secretion. To evaluate the role of the opioid and adrenergic systems in the hormonal dysfunction of anorexia nervosa (AN), we investigated the effects of naloxone and clonidine on serum GH, LH, FSH, beta-endorphin, TSH, prolactin and cortisol concentrations in 35 women with AN. Basal plasma beta-endorphin concentrations were significantly lower than those in healthy controls. The response of beta-endorphin to clonidine in the AN patients was increased, whereas the response of beta-endorphin to naloxone was decreased. Basal serum cortisol concentrations were significantly higher in the AN patients than that in the controls. There was a significant increase in the cortisol response to naloxone in the controls but a lack of cortisol response to naloxone in the patients with AN. Naloxone produced a significant increase in LH release in the controls during the luteal phase of the menstrual cycle, as well as in the majority of AN patients. Clonidine caused a diminution of LH in the controls and did not alter LH in the patients. After clonidine injection, a significant increase in GH release was observed in both groups of subjects. If these disturbances persist after normalization of body weight, it might suggest that altered opioid and adrenergic activity is an aetiological factor in the pathogenesis of anorexia nervosa.