AgRP and POMC neurons are hypophysiotropic and coordinately regulate multiple endocrine axes in a larval teleost

Cell Metab. 2012 Feb 8;15(2):256-64. doi: 10.1016/j.cmet.2011.12.014. Epub 2012 Jan 12.

Abstract

Plasticity in growth and reproductive behavior is found in many vertebrate species, but is common in male teleost fish. Typically, "bourgeois" males are considerably larger and defend breeding territories while "parasitic" variants are small and use opportunistic breeding strategies. The P locus mediates this phenotypic variation in Xiphophorus and encodes variant alleles of the melanocortin-4 receptor (MC4R). However, deletion of the MC4R has modest effects on somatic growth and reproduction in mammals, suggesting a fundamental difference in the neuroendocrine function of central melanocortin signaling in teleosts. Here we show in a teleost that the hypothalamic pro-opiomelanocortin and AgRP neurons are hypophysiotropic, projecting to the pituitary to coordinately regulate multiple pituitary hormones. Indeed, AgRP-mediated suppression of MC4R appears essential for early larval growth. This identifies the mechanism by which the central melanocortin system coordinately regulates growth and reproduction in teleosts and suggests it is an important anatomical substrate for evolutionary adaptation.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Agouti-Related Protein / metabolism*
  • Analysis of Variance
  • Animals
  • Body Weights and Measures
  • Hypothalamus / cytology*
  • Immunohistochemistry
  • In Situ Hybridization
  • Larva / growth & development
  • Larva / metabolism
  • Male
  • Neurons / cytology
  • Neurons / metabolism*
  • Oligonucleotides / genetics
  • Pituitary Hormones / metabolism*
  • Pro-Opiomelanocortin / metabolism*
  • Real-Time Polymerase Chain Reaction
  • Receptor, Melanocortin, Type 4 / metabolism
  • Signal Transduction / genetics
  • Signal Transduction / physiology*
  • Zebrafish / growth & development*

Substances

  • Agouti-Related Protein
  • Oligonucleotides
  • Pituitary Hormones
  • Receptor, Melanocortin, Type 4
  • Pro-Opiomelanocortin