Acute partner loss enhances social motivation and nucleus accumbens dopamine release in prairie voles
The loss of close social relationships leads to profound mental and physical health consequences across social species. We utilized the socially selective prairie vole (Microtus ochrogaster) to investigate how 5-day separation from a bonded mate or peer partner shapes social motivation and dopamine release kinetics in males and females. Prior to partner loss, baseline social motivation to access a partner or a novel object differed by sex and relationship type (mate vs. peer). Across all groups, however, separation induced heightened partner-seeking. Partner loss also enhanced dopamine signaling in the nucleus accumbens, increasing evoked dopamine release, the number of putative dopamine release sites, and tyrosine hydroxylase abundance, regardless of sex or relationship type. These findings suggest that mesolimbic reward circuitry adapts rapidly to the loss of a bonded partner, potentially signaling a critical social deficit across relationship types. Further, by leveraging high-resolution synthetic nanosensors, this study provides subcellular insights into presynaptic dopaminergic plasticity following partner loss, linking relationship loss to heightened social motivation and shifts in reward signaling.