Neuropeptide Y, but not agouti-related peptide or melanin-concentrating hormone, is a target peptide for orexin-A feeding actions in the rat hypothalamus.
We examined the effects of orexin A on the mRNA levels of neuropeptide Y, agouti-related peptide, melanin-concentrating hormone, prepro-orexin and orexin receptors in the rat hypothalamus. Adult male rats were treated centrally (i.c.v.) with a single dose of orexin A (3 nmol). After 2, 6 and 12 h, neuropeptide Y, agouti-related peptide, melanin-concentrating hormone, and prepro-orexin mRNA levels were measured by semiquantitative RT-PCR and in situ hybridization; orexin receptors mRNA content was quantified by semiquantitative RT-PCR. We found that orexin A increased neuropeptide Y expression in the arcuate nucleus of the rat hypothalamus. This stimulatory effect was transient, being observed 2 h after the treatment, and disappearing after longer periods (6 and 12 h). In contrast, no change was demonstrated in hypothalamic agouti-related peptide, melanin-concentrating hormone, prepro-orexin or orexin receptors mRNA levels at any time evaluated. Our results suggest that neuropeptide Y synthesized in the arcuate nucleus of the hypothalamus, but not agouti-related peptide and melanin-concentrating hormone pathways, is likely involved in orexin-induced feeding behavior, and raise the possibility that this functional linkage may also be involved in other actions mediated by orexins such as locomotor activity and sympathetic function.
López
Miguel
M
Department of Physiology, Faculty of Medicine, University of Santiago de Compostela, Santiago de Compostela, Spain.
Seoane
Luisa María
LM
García
María del Carmen
Mdel C
Diéguez
Carlos
C
Señarís
Rosa
R
D054369:Agouti-Related Protein; D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000502:physiology*; D002352:Carrier Proteins / Q000494:pharmacology*; D005247:Feeding Behavior / Q000502:physiology; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D007026:Hypothalamic Area, Lateral / Q000502:physiology; D007028:Hypothalamic Hormones / Q000235:genetics*; D036341:Intercellular Signaling Peptides and Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008543:Melanins / Q000235:genetics*; D009478:Neuropeptide Y / Q000235:genetics*; D009479:Neuropeptides / Q000235:genetics / Q000494:pharmacology*; D064446:Orexin Receptors; D000068797:Orexins; D010907:Pituitary Hormones / Q000235:genetics*; D011498:Protein Precursors / Q000235:genetics; D011506:Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide / Q000235:genetics
D054369:Agouti-Related Protein; D002352:Carrier Proteins; D007028:Hypothalamic Hormones; D036341:Intercellular Signaling Peptides and Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008543:Melanins; D009478:Neuropeptide Y; D009479:Neuropeptides; D064446:Orexin Receptors; D000068797:Orexins; D010907:Pituitary Hormones; D011498:Protein Precursors; D011506:Proteins; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide; C019463:melanin-concentrating hormone