Alcohol-preferring rats in colonies show withdrawal, inactivity, and lowered dominance.

Rats with free access to water and 10% alcohol were raised in enriched, social colonies for prolonged periods of time. Then those animals which had developed extreme alcohol or water preferences were identified for further study. These selected animals were marked and returned to the colony. Both high and low alcohol consumers showed increased alcohol consumption just prior to feeding, but only the high consumers had a peak of alcohol consumption during the early morning hours. Compared to low consumers, high alcohol consumers ate less food, ran less in the activity wheel, spent more time in the burrows, and ranked low on several dominance measures. When access to alcohol was removed in the colony, these high alcohol consumers became more active but remained low in dominance. When tested in photocell cages, they showed a pattern of hyperactivity suggesting withdrawal effects. This sub-population of animals from rat colonies who voluntarily prefer alcohol to water represent a novel and social animal model of chronic alcohol consumption.