Interaction of CCK and 8-OH-DPAT in the satiation of alcohol intake

Administration of the neuropeptide cholecystokinin (CCK) is known to reduce food and alcohol intake and preference. The food satiation effect of CCK is reportedly dependent on serotonergic neurotransmission. Administration of 8-OH-DPAT, a serotonin1A autoreceptor agonist, reduces the ability of CCK to inhibit feeding. We determined if CCK's alcohol satiation effect also depends on activity of serotonergic neurons by administering 8-OH-DPAT (120-240 microg/kg) to 23-h water-deprived female and male rats, followed 1 h later by i.p. injection of CCK (4 microg/kg) and 30-min access to 5% w/v ethanol. 8-OH-DPAT significantly (p < 0.05) interacted with CCK, and reduced CCK's ethanol satiation effect when given i.p. but increased CCK's effect when given s.c. Female rats showed this interaction of 8-OH-DPAT with CCK at a higher dose than males when given i.p., but females were more sensitive to s.c. 8-OH-DPAT's ability to reduce ethanol intake. Results are consistent with previous findings of dose-, sex-, and route-dependent biphasic effects of 8-OH-DPAT on feeding and ethanol intake. A partial dependence of CCK's alcohol satiation effect on serotonergic neurotransmission is revealed in this design.