Social structure and ethanol consumption in the laboratory rat.

When mixed-sex groups of rats in established colonies were given free access to 4% and then 8% ethanol solutions, relative ethanol consumption for individual subjects was consistent over the two solutions, with some subordinate males consuming much more ethanol than any of the dominant males. Overall, subordinate male consumption was significantly higher than that of dominants, suggesting that the social stress of subordination may be a factor in ethanol consumption. Offensive attack was reduced under 8% consumption conditions, compared to the pre-ethanol level. The significant negative correlation between initial offense level and the level of offense seen under 8% ethanol consumption agrees with previous work suggesting that more offensive males show a differential decline in offense with ethanol. Female colony members consumed significantly more ethanol than males, with some suggestion of increased drinking in response to social stresses. This pattern of results suggests that the colony situation may provide an important model for investigation of the relationship between social stress and ethanol consumption.