Effect of MAO A deficiency on different kinds of aggression and social investigation in mice.

Monoamine oxidase A (MAO A) degrades serotonin, dopamine and noradrenaline, factors critically involved in the regulation of aggression. Different kinds of aggression were investigated in Tg8, a transgenic mouse strain lacking a functional MAO A gene. MAO A-deficient mice differ from wild-type C3H/HeJ (C3H) in terms of showing higher territorial, predatory and isolation-induced aggression.