Neuronal relationship between orexin-A- and neuropeptide Y-induced orexigenic actions in goldfish.
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.
Kojima
Kenji
K
Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, 3190-Gofuku, Toyama 930-8555, Japan.
Kamijo
Motoki
M
Kageyama
Haruaki
H
Uchiyama
Minoru
M
Shioda
Seiji
S
Matsuda
Kouhei
K
D000818:Animals; D001921:Brain / Q000166:cytology; D004027:Diencephalon / Q000737:chemistry; D004435:Eating / Q000187:drug effects*; D006054:Goldfish; D007031:Hypothalamus / Q000737:chemistry; D047908:Intracellular Signaling Peptides and Proteins / Q000032:analysis*; D009474:Neurons / Q000737:chemistry*; D009478:Neuropeptide Y / Q000032:analysis* / Q000494:pharmacology*; D009479:Neuropeptides / Q000032:analysis*; D000068797:Orexins; D015398:Signal Transduction; D013566:Sympathomimetics / Q000032:analysis
D047908:Intracellular Signaling Peptides and Proteins; D009478:Neuropeptide Y; D009479:Neuropeptides; D000068797:Orexins; D013566:Sympathomimetics