Does the impairment of the hypothalamic-pituitary-gonadal axis in anorexia nervosa depend on increased sensitivity to endogenous melatonin?

The authors hypothesize that the impairment of hypothalamic-pituitary-gonadal axis in patients suffering from anorexia nervosa depends (at least in part) on the increased sensitivity to endogenous melatonin. The hypothesis is based mainly on the following facts: (1) melatonin is well known to exert an inhibitory effect on gonadotropin secretion; (2) melatonin binding is increased in brains of fasted rats; (3) undernutrition dramatically increases the inhibitory effect of exogenous melatonin on gonadotropin-releasing hormone-induced gonadotropin secretion in female rats; (4) the administration of propranolol in girls suffering from anorexia nervosa diminishes the nocturnal peak of melatonin and, in parallel, restores the gonadotropin response to gonadotropin-releasing hormone.