title: Why does insulin resistance develop during maturation?
abstract: We compared skeletal muscle glucose uptake between young and mature rats. Hindlimb perfusions at insulin concentrations of 0, 100, 250, or 10,000 microU/mL were performed on male Sprague-Dawley rats at 5 weeks or 4 months of age. Basal glucose uptake, and glucose uptake at all insulin concentrations were significantly lower in the 4-month-old mature rats (p < .05). This difference was most pronounced at maximally stimulating insulin concentrations. Skeletal muscle insulin receptor binding, autophosphorylation, and tyrosine kinase activity did not differ between young and mature rats. Surprisingly, GLUT-4 glucose transporter content was significantly higher in several muscles of the mature rats (p < .05). Therefore, the decline in insulin-stimulated glucose uptake in hindlimbs of mature rats cannot be explained by decreased activity of these steps in the glucose transport system.
authors.affiliation: Department of Medicine, Stanford University School of Medicine, California.
authors.forename: M J
authors.initials: MJ
authors.lastname: Reed
authors.forename: G M
authors.initials: GM
authors.lastname: Reaven
authors.forename: C E
authors.initials: CE
authors.lastname: Mondon
authors.forename: S
authors.initials: S
authors.lastname: Azhar
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D005947:Glucose / Q000378:metabolism; D051275:Glucose Transporter Type 4; D006614:Hindlimb; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology; D007333:Insulin Resistance; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000378:metabolism; D009124:Muscle Proteins; D009132:Muscles / Q000378:metabolism; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011972:Receptor, Insulin / Q000378:metabolism
chemical_list: D051275:Glucose Transporter Type 4; D007328:Insulin; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495694:Slc2a4 protein, rat; D011505:Protein-Tyrosine Kinases; D011972:Receptor, Insulin; D005947:Glucose