title: Adiponectin concentration is associated with muscle insulin sensitivity, AMPK phosphorylation, and ceramide content in skeletal muscles of men but not women.
abstract: Adiponectin is an adipokine that regulates metabolism and increases insulin sensitivity. Mechanisms behind this insulin-sensitizing effect have been investigated in rodents, but little is known in humans, especially in skeletal muscle. Women have higher serum concentrations of adiponectin than men and are generally more insulin sensitive in skeletal muscle than men. We show here that large differences exist between men and women with regard to apparent adiponectin regulation of insulin-stimulated glucose uptake in skeletal muscle. Serum adiponectin was significantly associated with leg glucose uptake in healthy, young, lean men, but the association was absent in women. In addition, serum adiponectin was significantly associated with AMP-activated protein kinase (AMPK) phosphorylation in skeletal muscles of men but not in women. Serum adiponectin was also significantly, negatively associated with skeletal muscle ceramide content in men only, and interestingly, ceramide content was negatively associated with adiponectin receptor 1 (AdipoR1) expression in skeletal muscles of men. Women had lower AdipoR1 expression in skeletal muscle and a lower percentage of glycolytic adiponectin-sensitive type 2 muscle fibers than men. These associations suggest that the insulin-sensitizing effect of adiponectin on human male skeletal muscles may be mediated via AdipoR1 to activation of AMPK, leading to lowering of ceramide content. The lower skeletal muscle AdipoR1 protein expression and lower expression of adiponectin-sensitive type 2 muscle fibers in women than in men may explain the apparent lesser sensitivity to adiponectin in women.
authors.affiliation: The August Krogh Centre, Molecular Physiology Group, Section of Human Physiology, Department of Exercise and Sport Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark.
authors.forename: Louise D
authors.initials: LD
authors.lastname: Høeg
authors.forename: Kim A
authors.initials: KA
authors.lastname: Sjøberg
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Lundsgaard
authors.forename: Andreas B
authors.initials: AB
authors.lastname: Jordy
authors.forename: Natalie
authors.initials: N
authors.lastname: Hiscock
authors.forename: Jørgen F P
authors.initials: JF
authors.lastname: Wojtaszewski
authors.forename: Erik A
authors.initials: EA
authors.lastname: Richter
authors.forename: Bente
authors.initials: B
authors.lastname: Kiens
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D052242:Adiponectin / Q000097:blood* / Q000378:metabolism; D000328:Adult; D002518:Ceramides / Q000378:metabolism*; D016207:Cytokines / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance / Q000502:physiology*; D050356:Lipid Metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D010766:Phosphorylation; D054419:Receptors, Adiponectin / Q000378:metabolism; D012039:Regional Blood Flow; D012737:Sex Factors; D055815:Young Adult
chemical_list: C475418:ADIPOR1 protein, human; D052242:Adiponectin; D002518:Ceramides; D016207:Cytokines; D007328:Insulin; D054419:Receptors, Adiponectin; D055372:AMP-Activated Protein Kinases; D005947:Glucose