Veterinary/zoology session

Children raised in aversive social environment are at risk to develop serious psychopathologies in adulthood, including antisocial behaviour and an inclination towards violence. Similar phenomena were noticed in various animal species as well: socially deprived animals showed an increase in aggressive behaviour in a number of studies. However, qualitative changes in social communication and aggressive behaviour have not yet been investigated in socially deprived animals.

The aim of the present experiments was to investigate qualitative and quantitative changes in aggressive behaviour of adult rats socially deprived from weaning. We used the resident-intruder paradigm to investigate aggression. In addition, we studied the autonomic response (using a biotelemetry setup) and plasma corticosterone levels of socially deprived rats during aggressive interaction. We also measured neuronal activation patterns in brain regions relevant to aggression by means of c-Fos immunohistochemistry.

Our data indicate that social deprivation leads to the emergence of violent forms of aggression, i.e. to attacks that are not signaled, are more frequent, stronger, and are aimed at vulnerable body parts (head, belly) of the opponent. Interestingly, increased violence was accompanied by enhanced defensive behaviour. Baseline corticosterone levels and corticosterone reactivity during aggressive interaction did not differ in socially deprived and control rats. However, similarly to antisocial people, they showed a marked autonomic hypoarousal during aggressive interaction as indicated by the reduced increase in heart rates compared to controls. Social deprivation induced an increased neuronal activation in the hypothalamic attack area which was not accompanied by changes in amygdalar nuclei.

Altered patterns of aggressive behaviour in socially deprived rats is a suitable model of some aspects of human psychopathologies resulting from social disturbances in childhood, e. g. antisocial personality disorder.