title: Effects of weaning and syndyphalin-33 on expression of melanocortinergic appetite-regulating genes in swine.
abstract: Syndyphalin-33 (SD-33) increases feed intake in sheep and recently weaned pigs. To assess the effects of SD-33 on hypothalamic gene expression, hypothalami were collected from unweaned pigs (n=19; 21±3 d of age) on day 0. Remaining pigs received an intramuscular injection of 0.5 μmole/kg SD-33 (SD) or saline (VEH) and weaned into individual pens. On days 1, 4, and 7 after weaning, hypothalami were collected from subsets of pigs (n=8 or 9) within each treatment group. Expression of μ-opioid receptor (MOR) was less in SD pigs than in VEH pigs on day 1 and day 4, suggesting down-regulation of the receptor by SD-33. Expression of hypothalamic melanocortin 4 receptor (MC4R) at 1 d after weaning was increased in VEH pigs (but not SD pigs) relative to levels before weaning. Expression of AGRP was not significantly altered by weaning or treatment at 1 d after weaning. At 4 d after weaning, expression of AGRP was greater in SD pigs than in VEH pigs, but at day 7 expression was less in SD pigs than in VEH pigs. A strong positive correlation was noted between expression levels of MOR and MC4R across treatment and time. Treatment with SD-33 appeared to partially abrogate the effects of weaning on expression of two key appetite-regulating genes within 24 h. Effects of SD-33 appear to be mediated at least in part by the μ-opioid receptor and include actions on the melanocortinergic pathway.
authors.affiliation: Department of Animal Science, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: T A
authors.initials: TA
authors.lastname: Cooper
authors.forename: S J
authors.initials: SJ
authors.lastname: Jenkins
authors.forename: L
authors.initials: L
authors.lastname: Wojakiewicz
authors.forename: H G
authors.initials: HG
authors.lastname: Kattesh
authors.forename: C J
authors.initials: CJ
authors.lastname: Kojima
mesh_terms: D054369:Agouti-Related Protein / Q000235:genetics / Q000502:physiology; D000818:Animals; D000833:Animals, Suckling; D004435:Eating / Q000502:physiology; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D007031:Hypothalamus / Q000502:physiology*; D008297:Male; D009842:Oligopeptides / Q000494:pharmacology*; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics; D044105:Receptor, Melanocortin, Type 4 / Q000235:genetics / Q000502:physiology; D017450:Receptors, Opioid, mu / Q000235:genetics / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D013552:Swine / Q000502:physiology*; D014886:Weaning
chemical_list: D054369:Agouti-Related Protein; D009842:Oligopeptides; D012333:RNA, Messenger; D044105:Receptor, Melanocortin, Type 4; D017450:Receptors, Opioid, mu; C030776:syndyphalin