antagonist inhibits, pair-bond formation in female individuals of this species (11). Moreover, there are notable differences in OTR distribution patterns among prairie voles and the non-monogamous montane voles (Microtus montanus), mainly in the brain region nucleus accumbens (12), and an OTR antagonist applied directly to this region blocks mating-induced partner preference formation (13). Furthermore, overexpression of the OTR in nucleus accumbens accelerates partner preference formation in female prairie voles (14). The molecular mechanism behind the differences in OTR expression has not yet been described, although differences in potential regulatory elements in the oxytocin receptor gene (OXTR), which could reflect variation in gene expression, have been found between prairie and montane voles (15). Similar to what has been shown in voles, a recent study has found that manipulations of OT activity alter partner-directed social behavior during pair interactions in the pair-bonding primate Black-tufted Marmoset (Callithrix penicillata) (16).
