CHOLECYSTOKININ IS A SATIETY HORMONE IN HUMANS AT PHYSIOLOGICAL POSTPRANDIAL PLASMA-CONCENTRATIONS

1. Intravenous infusions of the brain/gut hormone, cholecystokinin, have been shown to reduce food intake in a subsequent test meal. However, in previous studies the doses administered were large and likely to have produced plasma concentrations far in excess of the normal post-prandial range, 2, In this study cholecystokinin-8 was infused intravenously to six healthy subjects in doses that reproduced physiological post-prandial concentrations, Plasma concentrations of cholecystokinin were measured using a novel sensitive and specific radioimmunoassay, The effect of cholecystokinin-8 infusion on subsequent food intake in a standard test meal was compared with the effect of saline infusion in the same subjects, 3. Food intake (mean+/-SEM) was significantly less during cholecystokinin (5092+/-665kJ) than during saline infusion (6418+/-723kJ, P=0,03), During cholecystokinin infusion, plasma concentrations increased from 0.45+/-0.06 pmol/l to 7.28+/-2.43 pmol/l immediately before the meal, With saline infusion there was no premeal increase in plasma cholecystokinin concentration, 4, This paper describes a novel radioimmunoassay for measurement of plasma concentrations of cholecystokinin, Using this assay we have demonstrated that cholecystokinin is important in control of satiety in humans.