Rationale and objective: Group-housed male rats form social hierarchies, and under these conditions, it has been reported that subordinate (SUB) rats consume more alcohol than dominant (DOM) rats. We tested the hypothesis that a history of drinking alcohol would cause SUB rats to consume even greater amounts of alcohol. Methods: Male Long-Evans rats were trained to drink 10% alcohol or a sucrose/quinine solution equal in calories for 1 h/day using a sucrose-fading procedure. Subsequently, rats were housed in colonies (four males, two females) in a visible burrow system (VBS) for 14 days. Individual control male rats were housed in a tub cage with one female. Rats were removed from the VBS (or control environment) daily and given 1 h to drink alcohol or sucrose/quinine. Results: Colonies given daily access to sucrose/quinine formed clear DOM/SUB relationships in all measured parameters. Alcohol-drinking colonies failed to establish a dominance hierarchy and displayed little aggression, with an average of 14.6 ± 6.1 offensive attacks compared with 58.5 ± 12.3 attacks carried out by DOM sucrose/quinine rats. During VBS housing, alcohol and sucrose/quinine intake decreased independent of housing environment or social status. Conclusions: Contrary to prior reports of the effect of alcohol on aggressive behavior, moderate daily alcohol intake before and during VBS housing reduced aggression and precluded the formation of a dominance hierarchy in rats.
- Social stress
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