Background. Several recent studies have pointed to a dysfunction of serotonin transmission in patients with eating disorders. Notwithstanding, it is not known whether serotonergic abnormalities are related primarily to eating and/or purging behaviour, nutritional status or general psychopathological dimensions. Therefore, by using a validated neuroendocrine strategy, we investigated central serotonergic function in patients with anorexia nervosa, bulimia nervosa or binge-eating disorder who differ on the above parameters.

Methods. Plasma prolactin response to D-fenfluramine (30 mg p.o.) or placebo was measured in 58 drug-free female volunteers, comprising 15 underweight anorexic women, 18 bulimic women, 10 women with binge-eating disorder and 15 female healthy controls. Behavioural assessment included ratings of eating disorder symptoms, depression, aggression and food-related obsessions and compulsions.

Results. A significantly decreased prolactin response to D-fenfluramine was found in underweight anorexic women and in bulimics with high frequency bingeing ([ges ]2 binge episodes/day), but not in patients with binge-eating disorder or in bulimics with low frequency bingeing ([les ]1 binge episode/day). In the whole bulimic group, a negative correlation emerged between frequency of bingeing and prolactin response. No significant correlation was found between physical or psychopathological measures and the hormonal response in any group.

Conclusions. These results confirm our previous findings of an impaired serotonergic transmission in underweight anorexics and in bulimics with high frequency bingeing, but not in patients with less severe bulimia nervosa. Moreover, they show, for the first time, that the hypothalamic serotonergic system is not altered in women with binge-eating disorder.