A ROLE FOR CENTRAL VASOPRESSIN IN PAIR BONDING IN MONOGAMOUS PRAIRIE VOLES

MONOGAMOUS social organization is characterized by selective affiliati on with a partner, high levels of paternal behaviour and, in many spec ies, intense aggression towards strangers for defence of territory, ne st and mate1,2. Although much has been written about the evolutionary causes of monogamy, little is known about the proximate mechanisms for pair bonding in monogamous mammals2,3. The prairie vole, Microtus och rogaster, is a monogamous, biparental rodent which exhibits long-term pair bonds characterized by selective affiliation (partner preference) and aggression4,5. Here we describe the rapid development of both sel ective aggression and partner preferences following mating in the male of this species. We hypothesized that either arginine-vasopressin (AV P) or oxytocin (OT), two nine-amino-acid neuropeptides with diverse fo rebrain projections, could mediate the development of selective aggres sion and affiliation. This hypothesis was based on the following obser vations: (1) monogamous and polygamous voles differ specifically in th e distribution of forebrain AVP and OT receptors6,7; (2) AVP innervati on in the prairie vole brain is sexually dimorphic and important for p aternal behaviour8; (3) central AVP pathways have been previously impl icated in territorial displays and social memory9,10; and (4) central OT pathways have been previously implicated in affiliative behaviours1 1. We now demonstrate that central AVP is both necessary and sufficien t for selective aggression and partner preference formation, two criti cal features of pair bonding in the monogamous prairie vole.