Enhanced social motivation in briefly isolated male rats

Loneliness and anxiety are associated with psychiatric disorders in humans. Although brief social isolation in adult rats and mice has been proposed as a rodent model of loneliness, its socioemotional characteristics are not well known. In this study, we evaluated the social and emotional behaviors of adult male rats subjected to brief social isolation. Isolated rats frequently showed sniffing behavior toward empty cylinders where conspecifics had previously existed, as well as conspecifics themselves. Furthermore, social motivation correlated with anxiety levels, as indicated by the elevated plus-maze test performance in isolated but not in non-isolated rats. These results suggest that high social motivation is associated with anxiety in briefly isolated rats.