Hippocampus Oxytocin Signaling Promotes Prosocial Eating in Rats.

BACKGROUND: Oxytocin (OT) is a hypothalamic neuropeptide involved in diverse physiological and behavioral functions, including social-based behavior and food intake control. The extent to which OT's role in regulating these 2 fundamental behaviors is interconnected is unknown, which is a critical gap in knowledge given that social factors have a strong influence on eating behavior in mammals. Here, we focus on OT signaling in the dorsal hippocampus (HPCd), a brain region recently linked to eating and social memory, as a candidate system where these functions overlap. METHODS: HPCd OT signaling gain- and loss-of-function strategies were used in male Sprague Dawley rats that were trained in a novel social eating procedure to consume their first nocturnal meal under conditions that varied with regard to conspecific presence and familiarity. The endogenous role of HPCd OT signaling was also evaluated for olfactory-based social transmission of food preference learning, sociality, and social recognition memory. RESULTS: HPCd OT administration had no effect on food intake under isolated conditions but significantly increased consumption in the presence of a familiar but not an unfamiliar conspecific. Supporting these results, chronic knockdown of HPCd OT receptor expression eliminated the food intake-promoting effects of a familiar conspecific. HPCd OT receptor knockdown also blocked social transmission of food preference learning and impaired social recognition memory without affecting sociality. CONCLUSIONS: Collectively, the results of the current study identify endogenous HPCd OT signaling as a novel substrate in which OT synergistically influences eating and social behaviors, including the social facilitation of eating and the social transmission of food preference.