GABAergic neurons in the dorsal raphe nucleus regulate social hierarchy in mice

Social hierarchy serves as a fundamental organizational mechanism within most animal societies, however, the neural mechanisms governing dominance hierarchies remain inadequately understood. Considering that GABAergic neurons in the dorsal raphe nucleus (DRN) exert substantial inhibitory control over brain activity, we hypothesized that these neurons play a pivotal role in regulating social hierarchy. To test this, we employed a combination of optogenetics, chemogenetics, fiber photometry, and behavioral assays in mice to elucidate the functional contributions of these neurons. Our results revealed a biphasic activity pattern of DRN GABAergic neurons, characterized by increased firing during retreats and decreased firing during the initiation of effortful behaviors in the tube test. Furthermore, activation of these neurons led to an increase in the number of retreats and a reduction in social rank, while inhibition of these neurons produced the opposite effects. These findings elucidate the bidirectional regulatory role of DRN GABAergic neurons in social hierarchy.