[Monoamine oxidase activity in the brain of male laboratory mice differing in the capacity for social dominance].

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 the PT and CBA inbred laboratory lines with opposite dominance capabilities and in their direct and reciprocal F1 hybrids. MAO-B activity was shown to be lower in the hemispheres of intact PT males and F1 hybrid 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 F1 hybrid males and an increase in MAO-B activity in the brain stem of subordinant CBA and dominant F1 males.