Behavioural changes in laboratory mice during cannabis feeding and withdrawal.

The effects of feeding cannabis at a level of 0.4% in the diet has been studied by an ethological analysis of encounters between male mice. Administration of cannabis to dominant males resulted in a reduction of non-social activity and an increase in flight and in social and sexual investigation when compared with untreated controls, but the behaviour of subordinate males was not significantly altered by cannabis. One week after withdrawal of cannabis, the behaviour of diminant males showed a rebound effect with increase in aggression. Nevertheless, by a preference feeding test it was demonstrated that the treated mice were not dependent on the cannabis-containing diet but consumed the control diet in preference.