Distinct roles for prefrontal dopamine D1 and D2 neurons in social hierarchy.

Neuronal activity in the prefrontal cortex (PFC) controls dominance hierarchies in groups of animals. Dopamine (DA) strongly modulates PFC activity mainly through D1 receptors (D1Rs) and D2 receptors (D2Rs). Still, it is unclear how these two subpopulations of DA receptor-expressing neurons in the PFC regulate social dominance hierarchy. Here, we demonstrate distinct roles for prefrontal D1R- and D2R-expressing neurons in establishing social hierarchy, with D1R+ neurons determining dominance whereas D2R+ neurons for the subordinate. Ex vivo whole-cell recordings revealed that the dominant status of male mice correlates with rectifying AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor transmission and stronger excitatory synaptic strength onto D1R+ neurons in PFC pyramidal neurons. In contrast, the submissive status is associated with higher neuronal excitability in D2R+ neurons. Moreover, simultaneous manipulations of synaptic efficacy of D1R+ neurons in dominant male mice and neuronal excitability of D2R+ neurons of their male subordinates switch their dominant-subordinate relationship. These results reveal that prefrontal D1R+ and D2R+ neurons have distinct but synergistic functions in the dominance hierarchy, and DA-mediated regulation of synaptic strengths acts as a powerful behavioral determinant of intermale social rank.Significance StatementDominance hierarchy exists widely among animals who confront social conflict. Studies have indicated that social status largely relies on the neuronal activity in the prefrontal cortex, but how dopamine influences social hierarchy via subpopulation of prefrontal neurons is still elusive. Here, we explore the cell-type-specific role of dopamine receptor-expressing prefrontal neurons in the dominance-subordinate relationship. We found that the synaptic strength of D1 receptor-expressing neurons determines the dominant status, while hyperactive D2-expressing neurons are associated with the subordinate status. These findings highlight how social conflicts recruit distinct cortical microcircuits to drive different behaviors and reveal how D1- and D2-receptor enriched neurocircuits in the prefrontal cortex establish a social hierarchy.