An opioid-like system regulating feeding behavior in C. elegans

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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 C. 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.

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Mi Cheong Cheong

Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, United States

For correspondence
mccheong81@gmail.com

Competing interests
The authors declare that no competing interests exist.
Alexander B Artyukhin

Boyce Thompson Institute, Cornell University, Ithaca, United States

Competing interests
The authors declare that no competing interests exist.
Young-Jai You

Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, United States

Competing interests
The authors declare that no competing interests exist.
Leon Avery

Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, United States

Competing interests
The authors declare that no competing interests exist.

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