Central vasopressin and oxytocin release: regulation of complex social behaviours.

The neuropeptides arginine vasopressin (AVP) and oxytocin (OXT) are acknowledged as important modulators of diverse social behaviours. Here we discuss recent studies using intracerebral microdialysis to investigate the dynamics of AVP and OXT release patterns within distinct brain regions during the display of social behaviours in rats. Manipulation of local receptor-mediated actions of AVP and OXT via retrodialysis of either agonists or antagonists revealed the behavioural significance of changes in local neuropeptide release. Alterations in local AVP and OXT within, e.g. the medio-lateral septum, the central amygdala or the hypothalamic paraventricular nucleus (PVN) were associated with intermale and maternal aggression, respectively. Moreover, increased OXT release within the PVN was associated with male sexual behaviour and successful mating. Using retrodialysis, we found that AVP released within the lateral septum during the resident-intruder test was associated with anxiety-related behaviour and with non-aggressive social behaviour rather than intermale aggressive behaviour. In contrast, OXT release within the PVN and the central amygdala correlated positively with the level of maternal aggression. Interestingly, OXT released within the PVN during sexual activity in male rats was found to be associated with a robust decrease in anxiety-related behaviour up to 4h after mating. These data illustrate distinct modes of behavioural actions of AVP and OXT, reaching from acute regulation of the respective social behaviour to the long-term modulation of related behaviours including anxiety and social cognition. In conclusion, measuring the in vivo release patterns of AVP and OXT within distinct brain regions during the display of diverse social behaviours and manipulation of local AVP and OXT activity has yielded new insights into the specific roles of these neuropeptides in the regulation of complex social behaviours.