A Caenorhabditis elegans allatostatin/galanin-like receptor NPR-9 inhibits local search behavior in response to feeding cues.

ABSTRACT

Movement in Caenorhabditis elegans is the result of sensory cues creating stimulatory and inhibitory output from sensory neurons. Four interneurons (AIA, AIB, AIY, and AIZ) are the primary recipients of this information that is further processed en route to motor neurons and muscle contraction. C. elegans has >1,000 G protein-coupled receptors (GPCRs), and their contribution to sensory-based movement is largely undefined. We show that an allatostatin/galanin-like GPCR (NPR-9) is found exclusively in the paired AIB interneuron. AIB interneurons are associated with local search/pivoting behavior. npr-9 mutants display an increased local search/pivoting that impairs their ability to roam and travel long distances on food. With impaired roaming behavior on food npr-9 mutants accumulate more intestinal fat as compared with wild type. Overexpression of NPR-9 resulted in a gain-of-function phenotype that exhibits enhanced forward movement with lost pivoting behavior off food. As such the animal travels a great distance off food, creating arcs to return to food. These findings indicate that NPR-9 has inhibitory effects on the AIB interneuron to regulate foraging behavior, which, in turn, may affect metabolic rate and lipid storage.