A functional cellular framework for sex and estrous cycle-dependent gene expression and behavior

Sex hormones exert a profound influence on gendered behaviors. How individual sex hormone-responsive neuronal populations regulate diverse sex-typical behaviors is unclear. We performed orthogonal, genetically targeted sequencing of four estrogen receptor 1-expressing (Esr1⁺) populations and identified 1,415 genes expressed differentially between sexes or estrous states. Unique subsets of these genes were distributed across all 137 transcriptomically defined Esr1⁺ cell types, including estrous stage-specific ones, that comprise the four populations. We used differentially expressed genes labeling single Esr1⁺ cell types as entry points to functionally characterize two such cell types, BNSTpr^Tac1/Esr1 and VMHvl^Cckar/Esr1. We observed that these two cell types, but not the other Esr1⁺ cell types in these populations, are essential for sex recognition in males and mating in females, respectively. Furthermore, VMHvl^Cckar/Esr1 cell type projections are distinct from those of other VMHvl^Esr1 cell types. Together, projection and functional specialization of dimorphic cell types enables sex hormone-responsive populations to regulate diverse social behaviors.