Intracerebroventricular morphine enhances alcohol consumption by rats.

Previous experiments have shown that systemically administered low doses of opioid agonists increase subsequent alcohol consumption by rats. In this experiment, 10 micrograms of morphine were infused intracerebroventricularly (ICV) in free-feeding rats, daily for 6 days, 30 min prior to one-hour access to a 12% alcohol solution. Alcohol consumption was significantly increased in the morphine-treated group compared to that of a saline-treated control group, confirming that the locus of the effect is within the central nervous system.