[Brain monoamine oxidase and the predisposition for catalepsy in tame and aggressive Norway rats]

Aggressive Norway rats predisposed to catalepsy were characterized by an increased MAO B and dopamine-deaminating activities in the brainstem as compared to non-predisposed ones, MAO A activity being unchanged. Catalepsy-susceptible grey rats from a substrain of the tamed animals had lowered MAO A, MAO B, and dopamine-deaminating activities in the brainstem in comparison with the nonsusceptible ones. Among catalepsy-non-susceptible rats from both aggressive and tame populations, the brainstem MAO A and MAO B activities were considerably higher in tame animals than in aggressive ones.