Submitted to: American Journal of Physiology, Regulatory Integrative Comp. Physiology Address of correspondence

Glucagon-like peptide-1 (GLP-1) and cholecystokinin (CCK33) were intravenously infused alone or in combination into normal-weight men for 60 min before they were served a lunch of ham sandwiches, chocolate mousse and orange juice. Infusion of GLP-1 (dose: 0.9 pmol/kg/min) or CCK33 (dose: 0.2 pmol/kg/min) each reduced calorie intake of the test meal. However, simultaneous infusion of these peptide doses reduced calorie intake less than the sum of the peptides ' individual effects. Infusions of the same doses of GLP-1 plus CCK33 had neither individual nor interactive effects on meal size or calorie consumption. The combination of GLP-1 plus CCK33 induced, however, a significant reduction in hunger feelings in the pre-meal period (p=0.036 vs all other treatments). In summary, intravenous infusion of near physiological doses of CCK33 and GLP-1 produced specific inhibitions of feeling in men; the simultaneous infusion resulted in an infra-additive reduction in calorie consumption rejecting thereby the hypothesis that the two peptides exert a positive synergistic effect on food intake compared to the effects observed with infusion of individual peptides. In conclusion, CCK and GLP-1 are meal-related satiety signals that are released from the gastrointestinal tract during food intake. Revised Version