Effects of single and chronic intracerebroventricular administration of the orexins on feeding in the rat

• Published in: Peptides (New York, N.Y. : 1980) Vol. 20; no. 9; pp. 1099 - 1105
• Main Authors: Haynes, Andrea C, Jackson, Brian, Overend, Phil, Buckingham, Robin E, Wilson, Shelagh, Tadayyon, Mohammad, Arch, Jonathan R.S
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-09-1999
• Subjects: Animals; Carrier Proteins - administration & dosage; Carrier Proteins - pharmacology; Feeding; Feeding Behavior - drug effects; i.c.v. administration; Injections, Intravenous; Injections, Intraventricular; Intracellular Signaling Peptides and Proteins; Light-dark cycle; Male; Neuropeptides - administration & dosage; Neuropeptides - pharmacology; Orexins; Photoperiod; Rats; Rats, Sprague-Dawley; Rats, Wistar; Light-dark cycle; Orexins; i.c.v. administration; Feeding
• ISSN: 0196-9781; 1873-5169
• DOI: 10.1016/S0196-9781(99)00105-9

Two novel hypothalamic neuropeptides, orexin-A and -B, are suggested to regulate feeding. A single intracerebroventricular injection of orexin-A (23.4 nmol), administered 3 h into the light phase, increased feeding in satiated rats and prolonged feeding in fasted rats; it also increased feeding when given 6 h into, but not at the start of, the dark phase. An 8-day intracerebroventricular infusion with orexin-A (18 nmol/day) increased daytime feeding on days 2 and 8, but nocturnal feeding was reduced and there was no change in 24 h intake. Orexin-B had no effects. These results demonstrate a circadian variation in feeding responses to orexin-A.