Effects of morphine and haloperidol on agonistic behavior in male mice.

Morphine as well as haloperidol are considered potent antiaggressive drugs. There is a great deal of evidence that the dopaminergic system mediates many opiate effects, especially its rewarding actions. In this study, we compare the antiaggessive action of low doses of haloperidol (0.1 mg/kg) and morphine (1.25 and 2.5 mg/kg), using isolation induced-aggression, as a first step in the interaction research. Results pointed out that animals treated with haloperidol showed a significative decrease in time spent in attack behaviors and a significative increase in immobility behaviors with respect to control group. No differences in any behaviour were found in morphine treated groups. In these doses studied, both drugs have different actions on aggressive behaviors and locomotion