Alcohol, aggression and the stress of subordination

In individual resident-intruder or novel arena confrontations alcohol enhancement of aggression appears less robust than when groups of animals receive the drug. Patterns of effects in the latter situations, such as enhanced attack on familiar animals, particularly familiar females, suggest that group living engenders attack inhibitions, perhaps based on enhanced anxiety/defensiveness, that may be overcome by alcohol. Male rats living in natural, mixed-sex groups in seminatural situations develop strong dominance-subordination relationships that appear to strongly stress subordinates. Subordinate males show strongly and chronically increased defensive behaviors, increased corticosterone and reduced testosterone levels and, often, early mortality. When allowed access to both alcohol and water, they increase voluntary alcohol consumption, in comparison to dominants. Analyses of relationships between voluntary consumption and defensive behaviors support a view that the voluntary consumption increases of subordinate rats are mediated by the anxiolytic effect of alcohol in highly stressed animals.