title: Effects of an intravenous injection of NPY on leptin and NPY-Y1 receptor mRNA expression in ovine adipose tissue.
abstract: Neuropeptide Y (NPY) is highly expressed in hypothalami of undernourished and genetically obese animals, and is a potent regulator of food intake and reproduction. Leptin, a protein expressed by adipocytes, has been reported to reduce hypothalamic NPY expression. We recently detected (by ribonuclease protection assay [RPA]) expression of the NPY receptor subtype Y1 (but not Y2) mRNA in adipose tissue. Based on these observations we hypothesized that NPY-Y1 receptors in adipose may represent a peripheral mechanism by which NPY can regulate leptin expression in a direct and rapid manner. To test this hypothesis, adipose samples were biopsied from the tailhead region of 48 +/- 3 kg wether lambs immediately before and 30 min after a single intravenous injection of 50 micrograms porcine NPY ("treated" animals, n = 5), or vehicle ("control" animals, n = 4). Injection of NPY resulted in an increase in expression (P = 0.013; as measured by RPA) of both leptin and NPY-Y1 mRNA. In treated animals, negative correlations were found between response in leptin expression and body weight (r = -0.82, P = 0.092), and between leptin response and initial leptin mRNA levels (r = -0.81, P = 0.097). These data provide evidence of a peripheral mechanism by which NPY may regulate adipocyte expression of both leptin and NPY-Y1 receptor mRNA.
authors.affiliation: Department of Animal Science, University of Missouri, Columbia 65211, USA.
authors.forename: C J
authors.initials: CJ
authors.lastname: Dyer
authors.forename: J M
authors.initials: JM
authors.lastname: Simmons
authors.forename: R L
authors.initials: RL
authors.lastname: Matteri
authors.forename: D H
authors.initials: DH
authors.lastname: Keisler
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism*; D000818:Animals; D015870:Gene Expression / Q000187:drug effects*; D007275:Injections, Intravenous; D007328:Insulin / Q000097:blood; D020738:Leptin; D008297:Male; D009478:Neuropeptide Y / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D011506:Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D017476:Receptors, Neuropeptide Y / Q000235:genetics*; D012044:Regression Analysis; D012756:Sheep / Q000378:metabolism*
chemical_list: D007328:Insulin; D020738:Leptin; D009478:Neuropeptide Y; D011506:Proteins; D012333:RNA, Messenger; D017476:Receptors, Neuropeptide Y; C097212:neuropeptide Y-Y1 receptor