Social Regulation of Sex: How the Brain Controls Reproductive Circuits

Abstract

Social status regulates sexual behavior primarily via males that form and maintain dominance hierarchies. Status is typically established via physical conflict but sustained by social signals between individuals. High social status in males produces a suite of key hormones and behaviors culminating in the release of gonadotropin-releasing hormone (GnRH1) from the brain that signals the pituitary and, in turn, the gonads. In the highly social fish, Astatotilapia ( Haplochromis ) burtoni , dominance status is tightly coupled to fertility, and we have exploited this link to understand the regulatory systems from circulating hormones to gene expression that are controlled by social dominance. In reproductively active males, electrical synapses connect GnRH neurons, likely producing the necessary synchronous delivery of GnRH. Social opportunities produce rapid changes in gene expression in key brain nuclei, and both social success and failure produce changes in neuronal cell size and connectivity in reproductive centers of the brain. But how do animals perceive and use social information to modify their reproductive system and where is this information processed in the brain?