Inhibition of neuropeptide Y (NPY)-induced feeding and c-Fos response in magnocellular paraventricular nucleus by a NPY receptor antagonist: a site of NPY action.
Neuropeptide Y (NPY) is one of the important endogenous orexigenic peptides. In these studies we employed c-Fos immunostaining and a selective NPY Y1 receptor antagonist to identify the site of action of NPY in the hypothalamus. The results showed that intracerebroventricular administration of NPY stimulated feeding and increased immunostaining of c-Fos, a product of the immediate early gene c-fos, in several hypothalamic sites, including the dorsomedial nucleus, the supraoptic nucleus, and the two subdivisions of the paraventricular nucleus (PVN), the parvocellular PVN, and magnocellular PVN (mPVN). Intracerebroventricular administration of 1229U91, a selective NPY Y1 receptor antagonist, affected neither food intake nor c-Fos-like immunoreactivity (FLI) in these hypothalamic sites. Co-administration of NPY and NPY Y1 receptor antagonist inhibited NPY-induced food intake by 48%, but failed to affect NPY-induced FLI in the supraoptic nucleus, dorsomedial nucleus, and parvocellular PVN. However, this combined treatment decreased FLI by 46% in the mPVN (P < 0.05). These results showed that whereas NPY can stimulate FLI in several hypothalamic sites, the selective NPY Y1 antagonist suppressed NPY-induced FLI only in the mPVN. Thus, these findings lend credence to the view that a subpopulation of Y1 receptor-containing neurons in the mPVN in part mediate stimulation of feeding by NPY.
Yokosuka
M
M
Department of Physiology, University of Florida Brain Institute, University of Florida College of Medicine, Gainesville 32610-0244, USA.
Kalra
P S
PS
Kalra
S P
SP
D000818:Animals; D004435:Eating / Q000187:drug effects / Q000502:physiology*; D007150:Immunohistochemistry; D008297:Male; D009478:Neuropeptide Y / Q000037:antagonists & inhibitors / Q000494:pharmacology / Q000502:physiology*; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000502:physiology*; D010456:Peptides, Cyclic / Q000494:pharmacology; D016760:Proto-Oncogene Proteins c-fos / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017476:Receptors, Neuropeptide Y / Q000037:antagonists & inhibitors / Q000502:physiology*
C097287:1229U91; D009478:Neuropeptide Y; D010456:Peptides, Cyclic; D016760:Proto-Oncogene Proteins c-fos; D017476:Receptors, Neuropeptide Y