Effects of morphine and cocaine in mice with stable high aggressive and nonaggressive behavioral strategy.

The social group experience of mice with opposite aggressive and nonaggressive behavioral strategies was examined to modulate reinforcing effects of morphine and cocaine. Highly aggressive and nonaggressive male mice cohoused for long period in three-member groups were tested to self-administrate the drugs and to develop conditioned place preferring by them. Mouse triads formed by principle of descending aggression were used as a model of linear hierarchical group.