Corticotropin-releasing hormone mediates alpha-melanocyte-stimulating hormone-induced anorexigenic action in goldfish.
alpha-Melanocyte-stimulating hormone (alpha-MSH) and corticotropin-releasing hormone (CRH) both suppress food intake, and the alpha-MSH- or CRH-signaling pathway has possible potency to mediate anorexigenic actions induced by most other neuropeptides in goldfish. Therefore, using specific receptor antagonists, we examined whether the anorexigenic actions of alpha-MSH and CRH mutually interact. The inhibitory effect of ICV injection of the alpha-MSH agonist, melanotan II (MT II), on food intake was abolished by treatment with a CRH 1/2 receptor antagonist, alpha-helical CRH((9-41)), whereas the anorexigenic action of ICV-injected CRH was not affected by treatment with a melanocortin 4 receptor antagonist, HS024. This led us to investigate whether alpha-MSH-containing neurons in the goldfish brain have direct inputs to CRH-containing neurons, using confocal laser scanning microscopy. alpha-MSH- and CRH-like immunoreactivities were distributed throughout the brain, especially in the diencephalon. alpha-MSH-containing nerve fibers or endings lay in close apposition to CRH-containing neurons in a region of the hypothalamus, the nucleus posterioris periventricularis (NPPv). These results indicate that, in goldfish, alpha-MSH-induced anorexigenic action is mediated by the CRH-signaling pathway, and that CRH plays a crucial role in the regulation of feeding behavior as an integrated anorexigenic neuropeptide in this species.
Matsuda
Kouhei
K
Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, 3190-Gofuku, Toyama 930-8555, Japan. kmatsuda@sci.u-toyama.ac.jp
Kojima
Kenji
K
Shimakura
Sei-Ichi
S
Wada
Kohei
K
Maruyama
Keisuke
K
Uchiyama
Minoru
M
Kikuyama
Sakae
S
Shioda
Seiji
S
D000818:Animals; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology*; D004435:Eating / Q000187:drug effects*; D005260:Female; D005455:Fluorescent Antibody Technique; D006054:Goldfish; D007031:Hypothalamus / Q000737:chemistry; D007276:Injections, Intraventricular; D008297:Male; D009074:Melanocyte-Stimulating Hormones / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D010456:Peptides, Cyclic / Q000494:pharmacology; D000521:alpha-MSH / Q000031:analogs & derivatives / Q000494:pharmacology
C116098:HS 024; D010446:Peptide Fragments; D010456:Peptides, Cyclic; D000521:alpha-MSH; C027756:MSH, 4-Nle-7-Phe-alpha-; D009074:Melanocyte-Stimulating Hormones; D003346:Corticotropin-Releasing Hormone; C045089:corticotropin releasing hormone (9-41)