Neuronal relationship between orexin-A- and neuropeptide Y-induced orexigenic actions in goldfish

Neuropeptides. 2009 Apr;43(2):63-71. doi: 10.1016/j.npep.2009.01.004. Epub 2009 Mar 3.

Abstract

Orexin-induced orexigenic action is mediated by neuropeptide Y (NPY) in goldfish and rodents. A previous study indicated that NPY-induced orexigenic action may also be mediated by orexin-A in goldfish. However, there is little information about the mutual actions of orexin-A and NPY in the goldfish. Therefore, using their specific receptor antagonists, we examined whether the orexigenic actions of orexin-A and NPY mutually interact in the goldfish. The stimulatory effect of intracerebroventricular injection of NPY at 1 pmol/g body weight (BW) on food intake was abolished by treatment with the orexin receptor-1 antagonist, SB334867, at 10 pmol/g BW whereas the NPY Y1-receptor antagonist, BIBP3226, at 100 pmol/g BW attenuated orexin-A (at 2.8 pmol/g BW)-stimulated feeding. This led us, using a double-immunostaining method and confocal laser scanning microscopy, to investigate whether orexin-A- and NPY-containing neurons in the goldfish brain have direct mutual inputs. Orexin-A- and NPY-like immunoreactivities were distributed throughout the brain, especially in the diencephalon. Orexin-A- and NPY-containing neurons were located in a region of the hypothalamus, the nucleus posterioris periventricularis (NPPv), in close proximity to each other: NPY-containing nerve fibers or endings lay in close apposition to orexin-A-containing neurons in the NPPv, and orexin-A-containing nerve fibers or endings also lay in close apposition to NPY-containing neurons in the same region. These results indicate that, in goldfish, orexin-A- and NPY-induced orexigenic actions are mediated by mutual signaling pathways.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain / cytology
  • Diencephalon / chemistry
  • Eating / drug effects*
  • Goldfish
  • Hypothalamus / chemistry
  • Intracellular Signaling Peptides and Proteins / analysis*
  • Neurons / chemistry*
  • Neuropeptide Y / analysis*
  • Neuropeptide Y / pharmacology*
  • Neuropeptides / analysis*
  • Orexins
  • Signal Transduction
  • Sympathomimetics / analysis

Substances

  • Intracellular Signaling Peptides and Proteins
  • Neuropeptide Y
  • Neuropeptides
  • Orexins
  • Sympathomimetics