Oxytocin facilitates fidelity in well-established marmoset pairs by reducing sociosexual behavior toward opposite-sex strangers

Abstract

Summary Behavioral strategies that facilitate the maintenance of social bonds are critical for the preservation of high-quality social relationships. Central oxytocin (OT) activity modulates the behavioral features of socially monogamous relationships in a number of mammalian species (including marmoset monkeys), and plays a vital role in the behavioral maintenance of long-term social relationships. Two distinct variants of OT have been identified in some New World primates (including marmosets; Lee et al., 2011). The marmoset variant of the oxytocin ligand (Pro8-OT) is structurally distinct from the consensus mammalian variant of the oxytocin ligand (Leu8-OT), due to a proline substitution at the 8th amino-acid position. The goal of the present study was to determine if treating marmosets with Pro8-OT, relative to treatments with Leu8-OT, control saline, or an OT antagonist, had modulatory effects on the behavioral maintenance of long-term social relationships in marmosets. Treatment with the Pro8 variant, but not the Leu8 variant, of OT facilitated fidelity with a long-term partner by reducing time spent in close proximity with an opposite-sex stranger. However, this facilitative effect of Pro8-OT on proximity behavior manifested itself differently in male and female marmosets, such that females preferred to interact socially with their partner rather than a stranger when treated with Pro8-OT, while males spent less time in close proximity with both their partner and a stranger when treated with Pro8-OT. Furthermore, treatment with Pro8-OT, but not Leu8-OT, significantly delayed the expression of sexual solicitation behavior toward an opposite-sex stranger in both male and female marmosets, but had no effect on sociosexual behavior directed toward a long-term partner. These results suggest that the OT system is highly involved in reducing fidelity-threatening behaviors in well-established marmoset pairs, and that the effects were only produced by species-specific OT ligands.

Conditioned same-sex partner preference in male rats is facilitated by oxytocin and dopamine: Effect on sexually dimorphic brain nuclei

“…Acute administration of DA and OT agonists can produce drug-dependent effects on the preference for a partner and on sexual arousal, and general activity. Both facilitate erections [80], and OT may facilitates fidelity in some species [81]. However, conditioned same-sex partner preference in male rats (as observed in the present study) is not the result of pharmacological effects of QNP or OT, since the preference tests occurred four days after the last injection of the drugs, and exclusively in males that underwent cohabitation.…”

Evolutionary pattern in the OXT-OXTR system in primates: Coevolution and positive selection footprints

“…Thus, Cebidae OXT-8Pro and OXT-3Val-8Pro forms can be also connected with female behaviors. Recently, Cavanaugh and colleagues (40) showed that treatment with OXT-8Pro in C. jacchus facilitated fidelity in females, but not in males, but they unfortunately did not test other behaviors, including parental care.…”

Neurobiological mechanisms of social attachment and pair bonding

“…The OTR homolog mediates pair bonding behavior in monogamous zebra finches[20,21 • ,22]. OT and AVP regulate pair bonding behavior in marmosets and coppery titi monkeys, respectively[23–25]. Humans display a range of pair bonding behavior, and OXTR and AVPR1A gene variants are associated with relationship status [26,27]; plasma OT levels predict future success rates in romantic relationships [28]; and in romantically attached men, intranasal OT increases NAcc activity while viewing a partner’s face and increases preferred interpersonal distance from unfamiliar females[29 •• ,30].…”