Localization of oxytocin receptors in the prairie vole (Microtus ochrogaster) neocortex.

Early experience and social context interact to alter the phenotype of complex social behaviors. These early experiences can also result in alterations to cortical organization and connections. Given the ability of the neuropeptide oxytocin (OT) to modulate social and reproductive behavior, OT is likely involved in these cortical processes. However, little is known about the distribution of OT and OT receptors (OTR) within the neocortex. Using autoradiographic and neuroanatomical techniques, we characterized the cortical distribution of OT receptors (OTR) in prairie voles, a socially monogamous rodent species. We found that OTR density was low in the primary sensory areas (including primary somatosensory and auditory regions) but was quite high in association regions (including temporal and parietal association areas, and prelimbic regions). In the primary motor area as well as the temporal and parietal association areas, we observed differences in OTR density across cortical layers. Specifically, cortical layers 2/3 and 5 exhibited greater OTR density than layer 4. Our results point to a role for OT in integrating sensory and motor in the prairie vole brain, providing a complementary mechanism for the modulation of social interactions. Given the ability of early social experience and developmental manipulations of OT to affect the brain and behavior, these results suggest a novel mechanism for how OT may influence cortical organization.