title: Postexercise improvement in insulin-stimulated glucose uptake occurs concomitant with greater AS160 phosphorylation in muscle from normal and insulin-resistant rats.
abstract: Earlier research on rats with normal insulin sensitivity demonstrated that acute exercise increased insulin-stimulated glucose uptake (GU) concomitant with greater phosphorylation of Akt substrate of 160 kDa (pAS160). Because mechanisms for exercise effects on GU in insulin-resistant muscle are unknown, our primary objective was to assess insulin-stimulated GU, proximal insulin signaling (insulin receptor [IR] tyrosine phosphorylation, IR substrate 1-phosphatidylinositol-3-kinase, and Akt phosphorylation and activity), and pAS160 in muscles from acutely exercised (one session) and sedentary rats fed either chow (low-fat diet [LFD]; normal insulin sensitivity) or a high-fat diet (HFD; for 2 weeks, insulin-resistant). At 3 h postexercise (3hPEX), isolated epitrochlearis muscles were used for insulin-stimulated GU and insulin signaling measurements. Although exercise did not enhance proximal signaling in either group, insulin-stimulated GU at 3hPEX exceeded respective sedentary control subjects (Sedentary) in both diet groups. Furthermore, insulin-stimulated GU for LFD-3hPEX was greater than HFD-3hPEX values. For HFD-3hPEX muscles, pAS160 exceeded HFD-Sedentary, but in muscle from LFD-3hPEX rats, pAS160 was greater still than HFD-3hPEX values. These results implicated pAS160 as a potential determinant of the exercise-induced elevation in insulin-stimulated GU for each diet group and also revealed pAS160 as a possible mediator of greater postexercise GU of insulin-stimulated muscles from the insulin-sensitive versus insulin-resistant group.
authors.affiliation: Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MI.
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Castorena
authors.affiliation: Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MI.
authors.forename: Edward B
authors.initials: EB
authors.lastname: Arias
authors.affiliation: Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MISchool of Health Sciences, Central Michigan University, Mount Pleasant, MI.
authors.forename: Naveen
authors.initials: N
authors.lastname: Sharma
authors.affiliation: Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MIDepartment of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MIInstitute of Gerontology, University of Michigan, Ann Arbor, MI gcartee@umich.edu.
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Cartee
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D006003:Glycogen / Q000378:metabolism; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology*; D007333:Insulin Resistance; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D020690:GTPase-Activating Proteins; D007328:Insulin; C533101:TBC1D4 protein, rat; D006003:Glycogen; D005947:Glucose