Central effects of CCK ligands in pigs making operant responses for food

The effects, on operant feeding, of intracerebroventricular (ICV) injections of the CCKA receptor agonist A71623, the CCKB receptor agonist A63387, and the CCKA receptor antagonist A70104 were investigated in prepubertal pigs. In overnight starved animals, feeding was inhibited by 20, 5, and 1 micrograms doses of A71623 and by 20, but not 5 or 1 micrograms doses of A63387. In a second experiment, although pigs pretreated centrally with A70104 (20 micrograms) showed a tendency to eat more, the effect was not statistically significant. Furthermore, this dose of A70104 did not prevent the inhibition of feeding induced by a subsequent ICV injection of CCK (1 microgram). These findings support the view that exogenous CCK reduces food intake in pigs by acting, primarily, on CCKA receptors.