Facilitation of affiliation and pair-bond formation by vasopressin receptor gene transfer into the ventral forebrain of a monogamous vole

Behaviors associated with monogamy, including pair-bond formation, are faci litated by the neuropeptide vasopressin and are prevented by a vasopressin receptor [V1a receptor (V1aR)] antagonist in the male prairie vole. The neu roanatomical distribution of V1aR dramatically differs between monogamous a nd nonmonogamous species. V1aR binding is denser in the ventral pallidal re gion of several unrelated monogamous species compared with nonmonogamous sp ecies. Because the ventral pallidum is involved In reinforcement and addict ion, we hypothesize that V1aR activation In this region promotes pair-bond formation via a mechanism similar to conditioning. Using an adeno-associate d viral vector to deliver the V1aR gene, we increased the density of V1aR b inding in the ventral pallial region of male prairie voles. These males exh ibited increased levels of both anxiety and affiliative behavior compared w ith control males. In addition, males overexpressing the V1aR in the ventra l pallidal region, but not control males, formed strong partner preferences after an overnight cohabitation, without mating, with a female. These data demonstrate a role for ventral pallidal V1aR in affiliation and social att achment and provide a potential molecular mechanism for species differences in social organization.