title: Physical inactivity affects skeletal muscle insulin signaling in a birth weight-dependent manner.
abstract: OBJECTIVE
  We investigated whether physical inactivity could unmask defects in insulin and AMPK signaling in low birth weight (LBW) subjects.
  
  
  METHODS
  Twenty LBW and 20 normal birth weight (NBW) subjects were investigated using the euglycemic-hyperinsulinemic clamp with excision of skeletal muscle biopsies pre and post 9days of bed rest. Employing Western blotting, we investigated skeletal muscle Akt, AS160, GLUT4, and AMPK signaling.
  
  
  RESULTS
  Peripheral insulin action was similar in the two groups and was decreased to the same extent post bed rest. Insulin and AMPK signaling was unaffected by bed rest in NBW individuals. LBW subjects showed decreased insulin-stimulated Akt phosphorylation and increased AMPK α1 and γ3 protein expression post bed rest. Insulin response of AS160 phosphorylation was lower in LBW subjects both pre and post bed rest.
  
  
  CONCLUSIONS
  Bed rest-induced insulin resistance is not explained by impaired muscle insulin or AMPK signaling in subjects with or without LBW. Lower muscle insulin signaling in LBW subjects post bed rest despite similar degree of insulin resistance as seen in controls may to some extent support the idea that LBW subjects are at higher risk of developing type 2 diabetes when being physically inactive.
authors.affiliation: Steno Diabetes Center, Gentofte, Denmark; Molecular Physiology Group, The August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen. Electronic address: brym@steno.dk.
authors.forename: Brynjulf
authors.initials: B
authors.lastname: Mortensen
authors.affiliation: Steno Diabetes Center, Gentofte, Denmark; Molecular Physiology Group, The August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen.
authors.forename: Martin
authors.initials: M
authors.lastname: Friedrichsen
authors.affiliation: Molecular Physiology Group, The August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen.
authors.forename: Nicoline R
authors.initials: NR
authors.lastname: Andersen
authors.affiliation: Steno Diabetes Center, Gentofte, Denmark.
authors.forename: Amra C
authors.initials: AC
authors.lastname: Alibegovic
authors.affiliation: Department of Biomedical Sciences, University of Copenhagen; Center for Healthy Ageing, University of Copenhagen.
authors.forename: Lise
authors.initials: L
authors.lastname: Højbjerre
authors.affiliation: Department of Biomedical Sciences, University of Copenhagen; Center for Healthy Ageing, University of Copenhagen.
authors.forename: Mette P
authors.initials: MP
authors.lastname: Sonne
authors.affiliation: Department of Biomedical Sciences, University of Copenhagen.
authors.forename: Bente
authors.initials: B
authors.lastname: Stallknecht
authors.affiliation: Department of Biomedical Sciences, University of Copenhagen; Center for Healthy Ageing, University of Copenhagen.
authors.forename: Flemming
authors.initials: F
authors.lastname: Dela
authors.affiliation: Molecular Physiology Group, The August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen.
authors.forename: Jørgen F P
authors.initials: JF
authors.lastname: Wojtaszewski
authors.affiliation: Steno Diabetes Center, Gentofte, Denmark; Rigshospitalet, Department of Endocrinology, Denmark.
authors.forename: Allan
authors.initials: A
authors.lastname: Vaag
mesh_terms: D000328:Adult; D001724:Birth Weight / Q000502:physiology*; D016022:Case-Control Studies; D006801:Humans; D007231:Infant, Newborn; D007328:Insulin / Q000378:metabolism*; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism*; D012042:Registries; D057185:Sedentary Behavior; D015398:Signal Transduction; D055815:Young Adult
chemical_list: D007328:Insulin
keywords: AMPK; Fetal programming; Muscle signaling; Physical inactivity