Hypothalamic mapping of orexigenic action and Fos-like immunoreactivity following relaxin-3 administration in male Wistar rats

B. M. McGowan, S. A. Stanley, N. E. White, A. Spangeus, M. Patterson, E. L. Thompson, K. L. Smith, J. Donovan, J. V. Gardiner, M. A. Ghatei, S. R. Bloom

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59 Scopus citations

Abstract

The insulin superfamily, characterized by common disulphide bonds, includes not only insulin but also insulin-like peptides such as relaxin-1 and relaxin-3. The actions of relaxin-3 are largely unknown, but recent work suggests a role in regulation of food intake. Relaxin-3 mRNA is highly expressed in the nucleus incertus, which has extensive projections to the hypothalamus, and relaxin immunoreactivity is present in several hypothalamic nuclei. In the rat, relaxin-3 binds and activates both relaxin family peptide receptor 1, which also binds relaxin-1, and a previously orphaned G protein-coupled receptor, RXFP3. These receptors are extensively expressed in the hypothalamus. The aims of these studies were twofold: 1) map the hypothalamic site(s) of the orexigenic action of relaxin-3 and 2) examine the site(s) of neuronal activation following central relaxin-3 administration. After microinjection into hypothalamic sites, human relaxin-3 (H3; 180 pmol) significantly stimulated 0- to 1-h food intake in the supraoptic nucleus (SON), arcuate nucleus (ARC), and the anterior preoptic area (APOA) [SON 0.4 ± 0.2 (vehicle) vs. 2.9 ± 0.5 g (H3), P < 0.001; ARC 0.7 ± 0.3 (vehicle) vs. 2.7 ± 0.2 g (H3), P < 0.05; and APOA 0.8 ± 0.1 (vehicle) vs. 2.2 ± 0.2 g (H3), P < 0.05]. Cumulative food intake was significantly increased ≤8 h following administration into the SON and 4 h into the APOA. A significant increase in Fos-like immunoreactivity was seen in the SON following central relaxin-3 administration. Relaxin-3 stimulates feeding in several hypothalamic nuclei, and these studies provide additional support for relaxin-3 as an important peptide in appetite regulation.

Original languageEnglish
Pages (from-to)E913-E919
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume292
Issue number3
DOIs
StatePublished - Mar 2007
Externally publishedYes

Keywords

  • Appetite
  • Arcuate nucleus
  • Relaxin family peptide receptor 3
  • Supraoptic nucleus

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