Fig. 2.

Effects of inhibiting oxytocin receptor (OTR) activation in the caudal ventral tegmental area (VTA) with a highly selective OTR antagonist (Ant.) on the rewarding properties of social interaction in the conditioned place preference test. Males and females experienced same-sex social interaction in their initially non-preferred chamber and received injections of either saline or a highly selective OTR antagonist (90 μM) into the caudal VTA 5 min prior to social conditioning sessions. a The inverted U hypothesis predicts that antagonism of OTR activation reduces social reward in both males and females. b Male and female controls injected with saline in the VTA but not paired with other hamsters (i.e., No Social Saline) displayed no change in the time spent in the chambers during the post-test. In both males and females injected with saline prior to social interactions (Social Saline) there was an increase in the time spent in the social interaction paired chambers during the post-test. In both males and females, injection of the OTR antagonist into the VTA (Social OTR Antagonist) decreased the time spent in the social interaction paired chambers compared to saline injected controls during the post-test. c Male and female controls (i.e., No Social Saline) displayed no change in the social chamber preference score. In both males and females injected with saline prior to social interactions (Social Saline) there was an increase in the social chamber preference score. In both males and females, injections of the OTR antagonist into the VTA (Social OTR Antagonist) decreased the social chamber preference score compared to saline injected controls. (*indicates significant difference between groups, p < 0.05)