Satiety effects of cholecystokinin and caerulein in rabbits

Six adult rabbits were maintained on an 18 h fast, 6 h feeding schedule. At the end of the fast either 0.5-40 Ivy dog units (IDU)/kg cholecystokinin (CCK) or 0.9% NaCl were injected intravenously. Feed intake was then measured for 15 min. Significant depression of intake was found at 1 IDU/kg, a 50% depression of intake after 5.5 IDU/kg, and no intake after 40 IDU/kg. Caerulein in similar experiments gave significant depression of intake at 0.125 microgram/kg, a 50% depression after 0.28 microgram/kg, and no intake after 5.0 microgram/kg. In three of these rabbits subdiaphragmatic vagotomy did not abolish the satiety effects of CCK and caerulein. The synthetic octapeptide of CCK was less potent in causing satiety. After CCK or caerulein the rabbits showed typical postprandial behavior. Taste aversion tests failed to demonstrate a strong aversion to flavors associated with the compounds used. These results indicate that exogenous CCK can act as a satiety agent at levels of the same order as the physiological range.