Serotonin coordinates reproductive functions in Caenorhabditis elegans

Reproduction alters animal behavior and physiology, but neuronal circuits that coordinate these changes remain largely unknown. Insights into mechanisms that regulate and possibly coordinate reproduction-related traits could be gleaned from the study of sex pheromones that manipulate potential mating partners to improve reproductive success. In C. elegans , the prominent male pheromone, ascr#10, modifies reproductive behavior and several aspects of reproductive physiology in hermaphrodite recipients, including improving oocyte quality. Here we show that a circuit that contains serotonin-producing and serotonin-uptaking neurons plays a key role in mediating these beneficial effects of ascr#10. We also demonstrate that increased serotonergic signaling promotes proliferation of germline progenitors in adult hermaphrodites. Our results establish a role for serotonin in maintaining germline quality and highlight a simple neuronal circuit that acts as a linchpin that couples food intake, mating behavior, reproductive output, and germline renewal and provisioning.