Further studies of the aggressive behavior induced by delta9-tetrahydrocannabinol in REM sleep-deprived rats.

The aggressive behavior induced by delta9-tetrahydrocannabinol in pairs of REM sleep-deprived rats was studied in five experiments by measuring dominant and submissive behavioral patterns. When 2 REM-deprived rats received delta9-THC, one of the animals displayed very aggressive postures, while its partner assumed incomplete defensive postures. The intensity of these behavioral postures was dose-dependent. In pairs composed of one REM-deprived rat injected with delta9-THC and one normal or one REM-deprived partner injected with control solution the deprived/drugged rat showed an aggressive posture and catatonia, or a strikingly bizarre behavior, while the control partner displayed typical defensive postures. The behavioral alterations induced in REM-deprived rats by amphetamine, LSD-25, and pentobarbital failed to provoke defense postures in the normal rats paired with them; however, apomorphine partially mimicked the delta9-THC-effects. It is concluded that in REM-deprived rats delta9-THC not only provokes aggressive behavior but also impairs the defensive-submissive behavioral patterns.