Behavioral effects of hashish in mice. III. Social interactions between two residents and an intruder male.

The acute and subchronic effects of hashish extract (20 mg delta 9-THC/kg) on the social interactions between two drug-treated residents and an untreated intruder male were investigated. In this analysis 28 different behavioral elements were recorded. A single drug application suppressed all categories of behavior, except submissive behavior and flight, in dominant and subordinate residents. Treated animals were less active than controls and immobility was very frequent. An elevated total activity, due to an increase in non-social activities, was observed in the untreated intruder males of this group. Social investigation as well as submissive behavior and flight were reduced in these animals. On introduction of an untreated male after the fourth drug treatment of the residents, the drugged males showed tolerance to the sedative and most of the other behavioral effects of the drug, and intruder males behaved quite normally. The formation of a dominant-subordinate relation within the group was influenced neither by a single nor by repeated drug treatment. The acute and subchronic effects of hashish extract on social, especially aggressive behavior of males are compared to those described in previous papers and the variation in the results of the different studies is discussed.