Untreated rats develop “pathological” aggression when paired with a mescaline-treated rat in a shock-elicited aggression situation

Abstract

The species-typical aggressive repertoire of a pair of rats in a shock-elicited aggression situation consists of both rats assuming upright “boxing” postures and striking each other with their forepaws when electric shock is delivered. Aggressive behavior whose severity significantly exceeds this repertoire can be operationally defined as “pathological.” When mescaline hydrochloride is administered to a pair of rats in this situation, their aggressive behavior appears to qualify as pathological, since they will engage in vicious biting attacks that often result in death. In the present study the drug was given to only one member of the pair prior to placing both in a shock-elicited aggression situation. This was sufficient to cause the untreated member of the pair to bite viciously its mescaline-treated opponent, even though the latter generally remained passive or adopted submissive postures toward the untreated rat. The severity of viciousness was found to be significantly greater when both rats received the drug, indicating that the mescaline produces pathological aggression in rats in a shock-elicited aggression situation by altering the behavior of both the victim and attacker. It is hypothesized that pathological aggression in rats is due to mescaline's disruption of social signals that regulate the severity of aggressive behavior.