TESTMEAL RESPONSES FOLLOWING M-CHLOROPHENYLPIPERAZINE AND L-TRYPTOPHAN IN BULIMICS AND CONTROLS

A wealth of data support a role for serotonin (5-HT) function in the m ediation of satiety responses, that are impaired in patients with buli mia nervosa. Testmeal results are presented in which 26 bulimic patien ts and 17 normal controls were given in randomized, double-blind-fashi on, placebo, and the 5-HT agents m-chlorophenylpiperazine (m-CPP, 0.5 mg/kg p.o.) and L-tryptophan (L-TRP, 100 mg/kg I. V.). Three and one-h alf hours after drug administration, subjects were allowed to eat and lib from a standardized testmeal of 3,500 calories, after which postpr andial vomiting was not allowed. M-CPP, but not L-TRP, significantly d ecreased meal size in the combined group, the controls, and to a lesse r extent, the bulimics (p less than or equal to .06). Maximum m-CPP co ncentrations were inversely correlated to the number of calories consu med in the fetal group. Following m-CPP, there were significant decrea ses in carbohydrate, protein, and fat intake in the total group of sub jects. There were also trends for decreased carbohydrate and protein i ntake in the bulimics following m-CPP. There were trends for both m-CP P and L-TRP to reduce fat intake in the controls. Differences in the e ffects between m-CPP and L-TRP are likely due to differential involvem ent of 5-HT receptor subtypes at presynaptic and postsynaptic sites. T hese studies in humans confirm reports in animals that m-CPP decreases food intake, including carbohydrates, protein, and fat in a mixed tes tmeal.