Social reward plays different roles in mate and peer relationships in prairie voles

Abstract of poster PS2.0050 presented July 2018 at International Congress of Neuroendocrinology. Toronto, Canada. Prairie voles (Microtus ochrogaster) are widely studied for their reproductive pair-bonds, but individuals also demonstrate selective preferences for familiar same-sex peers. The mechanisms underlying pair-bonds in this species may differ from those underlying peer relationships, as reproductive partnerships and parental behaviors are highly motivated. We examined the role of reward and motivation in prairie vole peer relationships compared to prairie vole mate relationships through pharmacological manipulations of dopamine signaling as well as operant conditioning. Blockade of dopamine receptors with haloperidol did not alter selective preferences for familiar same-sex partners, suggesting that dopamine neurotransmission is not necessary for the formation of prairie vole peer relationships, unlike mate relationships. Voles were trained to press a lever to gain access to different types of social stimuli. Female voles pressed at higher rates to gain access to a mate than to a familiar same-sex peer. Once in the social chamber, females huddled significantly more with familiar mates or peers than with opposite- or same-sex strangers. These data support distinct roles of dopamine and motivation in peer relationships relative to pair-bonds: Although they are necessary to form and maintain pair-bonds, they are not necessary for peer relationships. The fact that a reproductive bond is mediated differently from a non-reproductive one suggests that peer relationships need to be further investigated in addition to pair-bonds to fully elucidate mechanisms of social behavior.