The role of neuropeptides in the disturbed control of appetite and hormone secretion in eating disorders.

OBJECTIVE: It has been reported that neuropeptides may play a role in the control of appetite and in the mechanism of hormone release. Neuropeptides such as beta-endorphin, neuropeptide Y (NPY), galanin and leptin may affect hormones release, on the other hand the hormonal status may modulate neuropeptide activity.

METHODS: The material consisted of 90 obese women, 30 women with Anorexia Nervosa, and 30 healthy, lean women of control group. Plasma beta-endorphin, NPY, leptin, somatostatin and serum pituitary and gonadal hormones concentrations were measured with RIA methods.

RESULTS: We observed the highest plasma NPY levels in obese hypertensive and diabetic patients. After carbohydrate administration (OGTT) a marked increase of insulin, beta-endorphin and NPY was found. The blunted response of GH to GH-RH may be connected with increased somatostatin activity and hyperinsulinemia. The abnormal response of LH to opioid blockade may be a result of disturbed opioid and NPY activities in obese patients. However in patients with anorexia nervosa, plasma leptin and NPY concentrations were low. The disturbances in beta-endorphin release are also observed.

CONCLUSIONS: The neuroendocrine disturbances in obesity and in anorexia nervosa are opposite. The feedback mechanism between leptin and NPY is disturbed in both in obesity and in anorexia nervosa. An abnormal activity of neuropeptides may lead to disturbed control of appetite and hormonal dysregulation in eating disorders.