MONOAMINE-OXIDASE ACTIVITY IN THE BRAINS OF MALE LABORATORY MICE DIFFERING IN SOCIAL-DOMINANCE CAPABILITY

The activity of type A and B monoamine oxidases (MAO-A and MAO-B) was studied in the brain stem and cerebral hemispheres of male mice from t he PT and CBA inbred laboratory lines with opposite dominance capabili ties and in their direct and reciprocal F-1 hybrids. MAO-B activity wa s shown to be lower in the hemispheres of intact PT males and F-1 hybr id males, which are genetically predisposed to social domination, than in CBA males. One-hour social stress imposed by grouping mice into a micropopulation resulted in a decrease in MAO-A and MAO-B activity in the hemispheres of dominant PT and F-1 hybrid males and an increase in MAO-B activity in the brain stem of subordinant CBA and dominant F-1 males.