Opioids, benzodiazepines and intake of ethanol.

Deprived rats were given the opportunity to take water or a sweetened ethanol solution for one hour/day. Across days, intake of the ethanol solution increased. Doses of morphine prior to an opportunity to drink increased avidity for the ethanol solutions, while doses of chlordiazepoxide did not. The opioid antagonist naloxone decreased intake, whereas, the benzodiazepine antagonist Ro 15-1788 failed to do so. These findings confirm that certain opioids can increase ethanol intake, and further specify that, under the same testing regimen, benzodiazepines do not reliably modify rats' propensity to drink a solution containing ethanol