Aggressiveness by isolation and brain serotonin turnover changes in different strains of mice.

In the framework of aggressive behavior a great amount of studies deal with altered brain monoamine levels or turnover. The involvement of brain serotonergic mechanisms in aggression has been demonstrated in the majority of the studies. In the present work, the biochemical and behavioral changes induced by prolonged socioenvironmental isolation in seven strains of mice were studied. Brain serotonin turnover varies significantly only in those strains which react to isolation with a constant degree of aggressiveness and there appears to exist an inverse correlation between these two parameters. Nevertheless a certain degree of aggression may develop even in the absence of alterations of brain serotonin turnover. Still the intensity of serotonin turnover decrease seems to represent a good indicator of the magnitude of the aggressive reaction.