Serotonergic Modulation of Social Dominance via the Dorsal Raphe–Central Amygdala Circuit in Male Mice

Social hierarchy is a fundamental aspect of social behavior in animals, influencing individual health and well‐being. This study investigated the role of serotonin (5‐HT) neurons in the dorsal raphe (DR) nucleus and their projections to the central amygdala (CeA) in regulating social dominance in male mice. We first observed elevated c‐Fos expression in 5‐HT neurons of subordinate mice, indicating heightened neuronal activity during social competition. Using chemogenetic approaches, we found that activation of DR 5‐HT neurons and DR 5‐HT ‐CeA projections significantly reduced the social rank of dominant individuals, while inhibition had negligible effects on the subordinates. Additionally, activation of the DR 5‐HT ‐CeA circuit induced anxiety‐like behaviors in dominant mice, as evidenced by reduced exploration in the open‐field test. Pharmacological blockade of 5‐HT1A receptors in the CeA reversed the effects of chemogenetic activation, highlighting the involvement of 5‐HT1A receptors in this process. These findings underscore the critical role of the DR 5‐HT ‐CeA circuit in modulating social dominance and suggest that 5‐HT1A receptors in the CeA play a pivotal regulatory role. Overall, the current study provides new insights into the neural mechanisms underlying social hierarchy, which is closely related to our health and welfare.