title: An opioid-like system regulating feeding behavior in C. elegans.
abstract: Neuropeptides are essential for the regulation of appetite. Here we show that neuropeptides could regulate feeding in mutants that lack neurotransmission from the motor neurons that stimulate feeding muscles. We identified nlp-24 by an RNAi screen of 115 neuropeptide genes, testing whether they affected growth. NLP-24 peptides have a conserved YGGXX sequence, similar to mammalian opioid neuropeptides. In addition, morphine and naloxone respectively stimulated and inhibited feeding in starved worms, but not in worms lacking NPR-17, which encodes a protein with sequence similarity to opioid receptors. Opioid agonists activated heterologously expressed NPR-17, as did at least one NLP-24 peptide. Worms lacking the ASI neurons, which express npr-17, did not response to naloxone. Thus, we suggest that Caenorhabditis elegans has an endogenous opioid system that acts through NPR-17, and that opioids regulate feeding via ASI neurons. Together, these results suggest C. elegans may be the first genetically tractable invertebrate opioid model.
authors.affiliation: Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, United States.
authors.forename: Mi Cheong
authors.initials: MC
authors.lastname: Cheong
authors.affiliation: Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, United States.
authors.forename: Alexander B
authors.initials: AB
authors.lastname: Artyukhin
authors.affiliation: Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, United States.
authors.forename: Young-Jai
authors.initials: YJ
authors.lastname: You
authors.affiliation: Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, United States.
authors.forename: Leon
authors.initials: L
authors.lastname: Avery
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism; D017124:Conserved Sequence; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology*; D005786:Gene Expression Regulation; D008969:Molecular Sequence Data; D009020:Morphine / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism*; D011957:Receptors, Opioid / Q000172:deficiency / Q000235:genetics*; D015398:Signal Transduction; D013217:Starvation / Q000378:metabolism
chemical_list: D029742:Caenorhabditis elegans Proteins; D009479:Neuropeptides; D011957:Receptors, Opioid; D009270:Naloxone; D009020:Morphine
keywords: C. elegans; feeding regulation; neuropeptide; neuroscience; opioid