Effects of social dominance on perineuronal nets in medial prefrontal cortex and basolateral amygdala

The medial prefrontal cortex contributes to many aspects of social behavior including the establishment and maintenance of dominance relationships. The development of dominance relationships also generates experience-dependent plasticity in cortical circuits controlling future social behavior and responses to stress. Perineuronal nets (PNN) are specialized extracellular structures that surround cortical neurons and contribute to experience-dependent neuroplasticity. Using a Syrian hamster model, we investigated whether the development of dominance relationships alters the expression of PNNs in the infralimbic (IL) and prelimbic (PL) regions of the ventral medial prefrontal cortex (vmPFC), as well as the basolateral amygdala (BLA). In addition, we tested whether status-dependent changes in PNN expression predicted changes in agonistic behavior. Female and male hamsters were paired with a weight-matched conspecific and exposed to daily dominance interactions for two weeks. Brains were collected after the final dominance interaction and PNN expression was measured throughout the rostral-caudal extent of the IL, PL, and BLA. While pairs of hamsters readily formed stable dominance relationships, pairs differed in their expression of PNNs, particularly within the medial prefrontal cortex. Furthermore, PNN expression correlated with both early and late phase agonistic behavior, elucidating the role of PNNs in both establishing and maintaining dominance status.