The course of aggressive behavior induced by a single injection of delta 9-tetrahydrocannabinol and its characteristics

Female, Wistar King A rats subjected to one day of isolated housing, during which all food was withheld for 22 hr and supplied for only 2 hr, and then given a single dose of Δ⁹-tetrahydrocannabinol (THC) markedly exhibited muricide and rod-attack behavior. This continued for 100 days after treatment as far as the animals remained in isolation. They displayed rat pup-killing behavior as well, although normal virgin female rats did not show such behavior. When the rats were transferred from isolated housing to group housing 60 days after THC treatment, rod-attack behavior disappeared completely in all rats and muricide disappeared in 13 of the 28 rats which exhibited muricide. However, when these rats were returned to isolation after a 15 day period of group housing, rod-attack behavior and muricide identical to that observed previously reappeared. It is concluded that housing condition plays a crucial role in the occurrence and maintenance of THC-induced aggression including muricide.