Brain cholecystokinin as a satiety peptide.

Injection of 0.08 microgram/kg of CCK-8 into the anterior cerebral ventricles of the rat produced a significant depression in the rat's motivation for food for at least one-half hour, as measured by running speed to food rewards in a runway and by food intake in a test-meal in the rat's home cage. Doses of 0.04 microgram/kg were ineffective and doses of 0.06 microgram/kg intermediate. There was no effect of 0.08 microgram/kg on running speed to water rewards. Intraperitoneal doses of 8.0 micrograms/kg also suppressed running speed and eating.