title: Calorie restriction enhances insulin-stimulated glucose uptake and Akt phosphorylation in both fast-twitch and slow-twitch skeletal muscle of 24-month-old rats.
abstract: Calorie restriction (CR) induces enhanced insulin-stimulated glucose uptake in fast-twitch (type II) muscle from old rats, but the effect of CR on slow-twitch (type I) muscle from old rats is unknown. The purpose of this study was to assess insulin-stimulated glucose uptake and phosphorylation of key insulin signaling proteins in isolated epitrochlearis (fast-twitch) and soleus (slow-twitch) muscles from 24-month-old ad libitum fed and CR (consuming 65% of ad libitum, intake) rats. Muscles were incubated with and without 1.2 nM insulin. CR versus ad libitum rats had greater insulin-stimulated glucose uptake and Akt phosphorylation (pAkt) on T308 and S473 for both muscles incubated with insulin. GLUT4 protein abundance and phosphorylation of the insulin receptor (Y1162/1163) and AS160 (T642) were unaltered by CR in both muscles. These results implicate enhanced pAkt as a potential mechanism for the CR-induced increase in insulin-stimulated glucose uptake by the fast-twitch epitrochlearis and slow-twitch soleus of old rats.
authors.affiliation: University of Michigan, School of Kinesiology, Room 4745F, 401 Washtenaw Avenue, Ann Arbor, MI 48109-2214, USA. gcartee@umich.edu
authors.forename: Donel A
authors.initials: DA
authors.lastname: Sequea
authors.forename: Naveen
authors.initials: N
authors.lastname: Sharma
authors.forename: Edward B
authors.initials: EB
authors.lastname: Arias
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Cartee
mesh_terms: D000375:Aging / Q000378:metabolism; D000818:Animals; D031204:Caloric Restriction; D020690:GTPase-Activating Proteins / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4 / Q000378:metabolism; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007150:Immunohistochemistry; D007328:Insulin / Q000494:pharmacology; D055504:Insulin Receptor Substrate Proteins / Q000378:metabolism; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D018656:Muscle Fibers, Fast-Twitch / Q000502:physiology*; D018657:Muscle Fibers, Slow-Twitch / Q000502:physiology*; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011972:Receptor, Insulin / Q000378:metabolism
chemical_list: D020690:GTPase-Activating Proteins; D051275:Glucose Transporter Type 4; D007004:Hypoglycemic Agents; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; C533101:TBC1D4 protein, rat; D011972:Receptor, Insulin; D051057:Proto-Oncogene Proteins c-akt; D005947:Glucose