title: Voluntary exercise prevents the obese and diabetic metabolic syndrome of the melanocortin-4 receptor knockout mouse.
abstract: Exercise is a mechanism for maintenance of body weight in humans. Morbidly obese human patients have been shown to possess single nucleotide polymorphisms in the melanocortin-4 receptor (MC4R). MC4R knockout mice have been well characterized as a genetic model that possesses phenotypic metabolic disorders, including obesity, hyperphagia, hyperinsulinemia, and hyperleptinemia, similar to those observed in humans possessing dysfunctional hMC4Rs. Using this model, we examined the effect of voluntary exercise of MC4R knockout mice that were allowed access to a running wheel for a duration of 8 wk. Physiological parameters that were measured included body weight, body composition of fat and lean mass, food consumption, body length, and blood levels of cholesterol and nonfasted glucose, insulin, and leptin. At the termination of the experiment, hypothalamic mRNA expression levels of neuropeptide Y (NPY), agouti-related protein (AGRP), proopiomelanocortin (POMC), cocaine- and amphetamine-regulated transcript (CART), orexin, brain-derived neurotropic factor (BDNF), phosphatase with tensin homology (Pten), melanocortin-3 receptor (MC3R), and NPY-Y1R were determined. In addition, islet cell distribution and function in the pancreas were examined. In the exercising MC4R knockout mice, the pancreatic islet cell morphology and other physiological parameters resembled those observed in the wild-type littermate controls. Gene expression profiles identified exercise as having a significant effect on hypothalamic POMC, orexin, and MC3R levels. Genotype had a significant effect on AGRP, POMC, CART, and NPY-Y1R, with an exercise and genotype interaction effect on NPY gene expression. These data support the hypothesis that voluntary exercise can prevent the genetic predisposition of melanocortin-4 receptor-associated obesity and diabetes.
authors.affiliation: Department of Pharmacodynamics, University of Florida, PO Box 100487, Gainesville, FL 32610, USA. carrie@cop.ufl.edu
authors.forename: Carrie
authors.initials: C
authors.lastname: Haskell-Luevano
authors.forename: Jay W
authors.initials: JW
authors.lastname: Schaub
authors.forename: Amy
authors.initials: A
authors.lastname: Andreasen
authors.forename: Kim R
authors.initials: KR
authors.lastname: Haskell
authors.forename: Marcus C
authors.initials: MC
authors.lastname: Moore
authors.forename: Lorraine M
authors.initials: LM
authors.lastname: Koerper
authors.forename: Francois
authors.initials: F
authors.lastname: Rouzaud
authors.forename: Henry V
authors.initials: HV
authors.lastname: Baker
authors.forename: William J
authors.initials: WJ
authors.lastname: Millard
authors.forename: Glenn
authors.initials: G
authors.lastname: Walter
authors.forename: S A
authors.initials: SA
authors.lastname: Litherland
authors.forename: Zhimin
authors.initials: Z
authors.lastname: Xiang
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight; D002784:Cholesterol / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics / Q000378:metabolism* / Q000517:prevention & control*; D005786:Gene Expression Regulation; D007328:Insulin / Q000097:blood; D020738:Leptin / Q000097:blood; D008099:Liver / Q000033:anatomy & histology / Q000378:metabolism; D008279:Magnetic Resonance Imaging; D051379:Mice; D018345:Mice, Knockout; D009765:Obesity / Q000235:genetics / Q000378:metabolism* / Q000517:prevention & control*; D009929:Organ Size; D010179:Pancreas / Q000033:anatomy & histology / Q000378:metabolism; D010641:Phenotype; D010805:Physical Conditioning, Animal / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D044105:Receptor, Melanocortin, Type 4 / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D001786:Blood Glucose; D007328:Insulin; D020738:Leptin; D012333:RNA, Messenger; D044105:Receptor, Melanocortin, Type 4; D002784:Cholesterol