Involvement of dopamine in inhibition of food intake by cholecystokinin octapeptide in male rats.

Deprivation of food reduced the level of dopamine in the cerebrospinal fluid of male rats and subsequent ingestion of food or intraperitoneal injection of cholecystokinin octapeptide restored the level. Injection of a dopamine receptor agonist (apomorphine) or cholecystokinin octapeptide inhibited food intake and these effects were reversed by pretreatment with a dopamine receptor antagonist (cis-flupentixol). Blockade of cholecystokinin-A receptors, by treatment with L-364,718, but not cholecystokinin-B receptors, by treatment with L-365,260, blocked the inhibitory effect of cholecystokinin octapeptide on food intake but did not affect the inhibitory effect of apomorphine. It is suggested that cholecystokinin interacts with dopamine in the control of food intake.