Effects of delta-9-tetrahydrocannabinol on social behaviour in the laboratory mouse and rat

The behavioural effects of delta-9-tetrahydrocannabinol in mice and rats have been studied by an ethological analysis of encounters between animals injected with the drug and partners injected with the solvent (Tween-saline). In both species, Immobility was increased and Non-Social Activity reduced after injections of 5 mg/kg of delta-9-tetrahydrocannabinol. Flight was increased in treated mice but not in treated rats. Aggression was not significantly altered in either species. Thus, in the mouse, the qualitative behavioural effects of delta-9-tetrahydrocannabinol were similar to those previously reported for crude cannabis resin. Comparison of the dose-response data indicated that some other constituents of cannabis may reduce the Flight reaction from delta-9-tetrahydrocannabinol although not interfering with Immobility.