Exercise training eliminates age-related differences in skeletal muscle insulin receptor and IRS-1 abundance in rats.
Insulin resistance is common in old age, and exercise training can improve insulin sensitivity. The purpose of this study was to determine the influence of age (6 vs 26 months) and exercise training (10 weeks of treadmill running) on insulin signaling protein abundance in skeletal muscle from male Fisher 344 rats. Muscle levels of insulin receptor (IR), insulin receptor substrate-1 (IRS-1), phosphatidylinositol 3-kinase (PI3K), and Akt1, a serine-threonine kinase, were determined. IRS-1 was reduced with aging, IR and PI3K abundance was greater in old rats, and Akt1 was unchanged. IRS-1 was increased by training in old but not young rats, and IR was increased by training in young but not old rats. PI3K tended to increase and Akt1 did not change with training, regardless of age. Aging does not uniformly affect insulin signaling protein abundance, and exercise differentially alters IR and IRS-1 in young and old rats, thereby eliminating age-related differences in these proteins.
Arias
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Biodynamics Laboratory and Department of Kinesiology, University of Wisconsin-Madison, WI 53706, USA.
Gosselin
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Cartee
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D000375:Aging / Q000378:metabolism*; D000704:Analysis of Variance; D000818:Animals; D015151:Immunoblotting; D055504:Insulin Receptor Substrate Proteins; D008297:Male; D023421:Models, Animal; D018482:Muscle, Skeletal / Q000201:enzymology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010750:Phosphoproteins / Q000032:analysis* / Q000378:metabolism*; D010805:Physical Conditioning, Animal; D011336:Probability; D011897:Random Allocation; D051381:Rats; D011916:Rats, Inbred F344; D011972:Receptor, Insulin / Q000032:analysis / Q000378:metabolism*; D012016:Reference Values; D012680:Sensitivity and Specificity
D055504:Insulin Receptor Substrate Proteins; C526296:Irs1 protein, rat; D010750:Phosphoproteins; D019869:Phosphatidylinositol 3-Kinases; D011972:Receptor, Insulin