title: Glucosamine and glucose induce insulin resistance by different mechanisms in rat skeletal muscle.
abstract: It has been hypothesized that glucose-induced insulin resistance is mediated by accumulation of UDP-N-acetylhexosamines (UDP-HexNAcs). In a previous study on rat epitrochlearis muscles incubated with high concentrations of glucose and insulin (Kawanaka K, D-H Han, J Gao, LA Nolte, and JO Holloszy. J Biol Chem 276: 20101-20107, 2001), we found that insulin resistance developed even when the increase in UDP-Hex-NAcs was prevented. Furthermore, actinomycin D completely prevented glucose-induced insulin resistance despite a greater accumulation of UDP-HexNAcs. In the present study, we used the same epitrochlearis muscle preparation, as well as the rat hemidiaphragm, to determine whether, like glucose, glucosamine causes insulin resistance by an actinomycin D-inhibitable process. Incubation of diaphragm muscles with 10 mM glucosamine for 3 h resulted in an approximately fivefold increase in UDP-HexNAcs, an approximately 50% reduction in insulin responsiveness of glucose transport, and a 58% reduction in ATP concentration. These effects of glucosamine were not prevented by actinomycin D. Incubation of epitrochlearis muscles with 20 mM glucosamine for 3 h or with 10 mM glucosamine for 5 h also caused large decreases in insulin responsiveness of glucose transport but with no reduction in ATP concentration. Actinomycin D did not prevent the glucosamine-induced insulin resistance. The insulin-induced increases in tyrosine phosphorylation of insulin receptor substrate (IRS)-1 and the binding of PI 3-kinase to IRS-1 were decreased approximately 60% in epitrochlearis muscles exposed to glucosamine. This is in contrast to glucose-induced insulin resistance, which was not associated with impaired insulin signaling. These results provide evidence that glucosamine and glucose induce insulin resistance by different mechanisms.
authors.affiliation: Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
authors.forename: Dong-Ho
authors.initials: DH
authors.lastname: Han
authors.forename: May M
authors.initials: MM
authors.lastname: Chen
authors.forename: John O
authors.initials: JO
authors.lastname: Holloszy
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D046508:Culture Techniques; D003609:Dactinomycin / Q000378:metabolism; D003964:Diaphragm / Q000378:metabolism; D005552:Forelimb / Q000378:metabolism; D005944:Glucosamine / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D006595:Hexosamines / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000502:physiology; D014530:Uridine Diphosphate / Q000031:analogs & derivatives* / Q000378:metabolism*
chemical_list: C112928:5-azido-UDP-acetylhexosamine; D006595:Hexosamines; D007328:Insulin; D003609:Dactinomycin; D014530:Uridine Diphosphate; D000255:Adenosine Triphosphate; D005947:Glucose; D005944:Glucosamine