Male, but not female, oxytocin receptor knockout prairie voles (Microtus ochrogaster) show impaired consolation behavior.

Prosocial behaviors, including empathetic consoling toward others, contribute to maintaining social groups and social connections between individuals in many mammalian species, including monogamous prairie voles (Microtus ochrogaster). Prairie voles display consolation toward distressed partners by increasing allogrooming behavior toward the partner. A previous pharmacological study showed that oxytocin signaling contributes to consolation in male prairie voles, although possible sex differences in the regulation of consoling have not been explored. Here, we demonstrate that male, but not female, oxytocin receptor knockout (Oxtr-/-) prairie voles display disrupted consoling behavior toward distressed opposite sex partners who spend 24 h with their partners to form a pair bond. Notably, both male and female Oxtr-/- prairie voles showed normal partner preference following 24 h of cohabitation. Autoradiography for the vasopressin 1a receptor (AVPR1A) reveals no differences between genotypes in AVPR1A levels in the lateral septum, ventral pallidum, laterodorsal thalamic nucleus, and central amygdala, suggesting that the lack of OXTR does not lead to compensation via AVPR1A system at the receptor expression level in these selected brain regions. These findings demonstrate that OXTR modulates consolation in a sex-specific manner in prairie voles, while the lack of OXTR does not influence pair bonding.