title: Adiponectin resistance precedes the accumulation of skeletal muscle lipids and insulin resistance in high-fat-fed rats.
abstract: High-fat (HF) diets can induce insulin resistance (IR) by altering skeletal muscle lipid metabolism. An imbalance between fatty acid (FA) uptake and oxidation results in intramuscular lipid accumulation, which can impair the insulin-signaling cascade. Adiponectin (Ad) is an insulin-sensitizing adipokine known to stimulate skeletal muscle FA oxidation and reduce lipid accumulation. Evidence of Ad resistance has been shown in obesity and following chronic HF feeding and may contribute to lipid accumulation observed in these conditions. Whether Ad resistance precedes and is associated with the development of IR is unknown. We conducted a time course HF feeding trial for 3 days, 2 wk, or 4 wk to determine the onset of Ad resistance and identify the ensuing changes in lipid metabolism and insulin signaling leading to IR in skeletal muscle. Ad stimulated FA oxidation (+28%, P < or = 0.05) and acetyl-CoA carboxylase phosphorylation (+34%, P < or = 0.05) in control animals but failed to do so in any HF-fed group (i.e., as early as 3 days). By 2 wk, plasma membrane FA transporters and intramuscular diacylglycerol (DAG) and ceramide were increased, and insulin-stimulated phosphorylation of both protein kinase B and protein kinase B substrate 160 was blunted compared with control animals. After 4 wk of HF feeding, maximal insulin-stimulated glucose transport was impaired compared with control. Taken together, our results demonstrate that an early loss of Ad's stimulatory effect on FA oxidation precedes an increase in plasmalemmal FA transporters and the accumulation of intramuscular DAG and ceramide, blunted insulin signaling, and ultimately impaired maximal insulin-stimulated glucose transport in skeletal muscle induced by HF diets.
authors.affiliation: Department of Human Health and Nutritional Sciences, University of Guelph, Ontario, Canada, N1G 2W1.
authors.forename: Kerry L
authors.initials: KL
authors.lastname: Mullen
authors.forename: Janet
authors.initials: J
authors.lastname: Pritchard
authors.forename: Ian
authors.initials: I
authors.lastname: Ritchie
authors.forename: Laelie A
authors.initials: LA
authors.lastname: Snook
authors.forename: Adrian
authors.initials: A
authors.lastname: Chabowski
authors.forename: Arend
authors.initials: A
authors.lastname: Bonen
authors.forename: David
authors.initials: D
authors.lastname: Wright
authors.forename: David J
authors.initials: DJ
authors.lastname: Dyck
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D000103:Acetyl-CoA Carboxylase / Q000378:metabolism; D052242:Adiponectin / Q000378:metabolism; D000818:Animals; D018955:CD36 Antigens / Q000097:blood; D002518:Ceramides / Q000378:metabolism; D004041:Dietary Fats / Q000008:administration & dosage / Q000378:metabolism*; D004075:Diglycerides / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000378:metabolism*; D007333:Insulin Resistance; D050356:Lipid Metabolism; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism*; D010084:Oxidation-Reduction; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D013997:Time Factors
chemical_list: D052242:Adiponectin; C499920:Adipoq protein, rat; D018955:CD36 Antigens; D002518:Ceramides; D004041:Dietary Fats; D004075:Diglycerides; D005227:Fatty Acids; D051057:Proto-Oncogene Proteins c-akt; D055372:AMP-Activated Protein Kinases; D000103:Acetyl-CoA Carboxylase; D005947:Glucose