Single-housed, but not pair-housed, male and female rats demonstrate social conditioned place preference.

Understanding the factors that modulate social reward has important implications for conditions characterized by social dysfunction, including autism spectrum disorder and social anxiety disorder. Social isolation is particularly relevant, given rising rates of subjective loneliness and social disconnection in the United States. The present study investigated the impacts of isolation on social reward by testing the effects of single- versus pair-housing on social conditioned place preference (sCPP) in adult male and female Sprague-Dawley rats. Across a ten-day paradigm with eight conditioning days, rats were trained in a two-chamber apparatus in which one chamber was repeatedly paired with a same-sex, weight-matched littermate, while the other chamber served as an unpaired control. Pair-housed rats were co-housed with their conditioning partner for the duration of the study. Single-housed, but not pair-housed, rats of both sexes developed a significant preference for the social-paired chamber. These findings indicate that housing condition modulated sCPP expression in adult male and female rats.