Type-A CCK receptors mediate the inhibition of food intake and activity by CCK-8 in 9- to 12-day-old rat pups

To determine the type of cholecystokinin (CCK) receptor that mediates the inhibitory effects of peripherally administered CCK-8 on food intake and activity in 9- to 12-day-old rat pups, we gave injections of a type-A CCK receptor antagonist, MK-329, or of the type-B CCK receptor antagonist, L-365,260, prior to CCK-8 (IP). MK-329 reversed the inhibitory effects of CCK-8, but L-365,260 did not. This demonstrates that the inhibitory effects of CCK-8 (IP) are mediated by type-A, but not type-B, CCK receptors in pups of this age.