Heightened aggressive behavior by animals interacting with alcohol-treated conspecifics: studies with mice, rats and squirrel monkeys.

Drug-free mice, rats and squirrel monkeys showed more aggression toward alcohol-treated conspecifics than under control conditions. Quantitative ethological analysis was used to assess the dose-dependent effects of ethyl alcohol on a range of aggressive, submissive, defensive, escape responses as well as on non-agonistic behavior such as associative responses, grooming, and locomotor activities. Two experimental situations were studied: resident-intruder confrontations in mice and rats, and interactions between members of established groups of squirrel monkeys. After PO administration of ethyl alcohol to intruder mice and rats, the non-drugged resident mice and rats attacked, threatened, and pursued intruders at higher frequencies during 5-min encounters. Similarly, subordinate squirrel monkeys who were members of three established groups, when given alcohol, were grasped, displaced, and displayed to more frequently by non-drugged group members than after water control injections during the first 40 min after injection. This change in aggressive behavior by non-drugged animals was related to the alcohol dose given to the intruder or subordinate animal; near-ataxic alcohol doses (3.0 g/kg in mice, 1.7 g/kg in rats, 1.0 g/kg in squirrel monkeys) altered the behavior of animals whose prevalent pattern is defensive and submissive so that they were the subject of most frequent and intense aggression.