Vasopressin modulates male squirrel monkeys' behavior during social separation.

The central administration of arginine-vasopressin (AVP) in rodents has been associated with the modulation of a number of categories of behavior including social recognition and learning, aggression, grooming, and feeding. Concentrations of AVP in brain have also been functionally related to gonadal steroid hormone manipulations. In the current experiments we investigated the behavioral effects of centrally administered AVP on the behavior of pair-housed male squirrel monkeys during brief social separations. Prior to treatment, pairs of male squirrel monkeys established reliable and persistent dominance relationships measured as different patterns of social behavior and plasma levels of testosterone. Central administration of AVP increased scent-marking and grooming behaviors during the social separation test, however these effects were not influenced by the social status of the treated monkey. The effects of AVP on these measures were not mimicked by doses of oxytocin (OT). Both AVP and OT decreased the frequency of vigilance-checking and 'isolation-peep' calls. The data are consistent with a facilitatory role for AVP in the stress response and also suggest that these particular effects are not influenced by differences in testosterone associated with social dominance.