Histidyl proline diketopiperazine (Cyclo [His-Pro]) in eating disorders.

The authors explored the role of Cyclo [His-Pro] (CHP) in 50 adolescents who fulfilled DSM III diagnostic criteria for anorexia nervosa and bulimia. CHP, a relatively new neuro modulator which has a role in inducing satiety, was assayed in serum during routine blood work. CHP levels correlated significantly with weight in restrictor (AN-R) (R = -0.449, P less than 0.05) and bulimic anorexics (AN-B) (R = +0.489, P less than 0.01). There was no significant correlation in normal-weight bulimics (NWB) (R = +0.556, P less than 0.01). It did not correlate with weight in a depressed control group. Longitudinal data on six patients showed a similar relationship between weight, purging and CHP binge/purge activity and/or weight changes of around 2 kilograms correlated with average CHP changes of 42%. Clinical material suggests changes in satiety during CHP changes consistent with a satiety disturbance model of these disorders.