[Brain monoamine oxidase in mink selected for their reaction to man]

Monoamineoxidase activity was studied in minks of three behavioural groups--those bred for absence of aggression towards man, those bred for high aggression to man, and those of non-selected population. Breeding for the absence of aggression was accompanied by a decrease of MAO-B activity with unchanged MAO-A activity. The minks bred for aggressive behaviour towards man, as compared to those bred for the absence of aggression, were characterised by increased MAO-A and MAO-B activities in the brain stem. The effect of emotional stress on MAO-A and MAO-B was similar in aggressive, non-aggressive and unselected minks and was expressed in a decrease of both MAO-A and MAO-B activity. The MAO activity of cerebral hemispheres remained unaffected both by selection for behaviour and by the emotional stress.