Tested the effects of cholecystokinin (CCK) on a total of 120 adult male Sprague-Dawley rats. Partially purified CCK was injected intraperitoneally into fasted Ss prior to food presentation. The hormone produced a large dose-related suppression of intake of solid and liquid diets. Identical doses of the synthetic terminal octapeptide of cholecystokinin produced identical results. An effective dose of CCK did not suppress drinking after water deprivation. Treated Ss did not appear ill and were not hyperthermic; neither CCK nor the octapeptide produced learning of a taste aversion in bait-shyness tests. The effect of CCK is not a property of all gut hormones, since injections of secretin did not affect feeding. These studies raise the possibility that CCK plays an inhibitory role in the short-term control of feeding behavior. (25 ref.) (PsycINFO Database Record (c) 2006 APA, all rights reserved)