ASI regulates satiety quiescence in C. elegans

Abstract

In Caenorhabditis elegans, satiety quiescence mimics behavioral aspects of satiety and postprandial sleep in mammals.Onthe basis of calciumimaging, genetics, and behavioral studies, here we report that a pair of amphid neurons, ASI, is activated by nutrition and regulates worms' behavioralstatesspecificallypromotingsatietyquiescence;ASIinhibitstheswitchfromquiescencetodwelling(abrowsingstate)andaccelerates the switch from dwelling to quiescence. The canonical TGFβ pathway, whose ligand is released from ASI, regulates satiety quiescence. The mutants of a ligand, a receptor and SMADs in the TGFβ pathway all eat more and show less quiescence than wild-type. The TGFβ receptor in downstream neurons RIM and RIC is sufficient for worms to exhibit satiety quiescence, suggesting neuronal connection from ASI to RIM and RICis essential for feeding regulationthroughtheTGFβ pathway.ASIalso regulates satiety quiescence partlythroughcGMPsignaling; restoring cGMP signaling in ASI rescues the satiety quiescence defect of cGMP signaling mutants. From these results, we propose that TGFβ and cGMP pathways in ASI connect nutritional status to promotion of satiety quiescence, a sleep-like behavioral state. © 2013 the authors.