title: Effects of aerobic exercise training on the protein kinase B (PKB)/mammalian target of rapamycin (mTOR) signaling pathway in aged skeletal muscle.
abstract: The protein kinase B (PKB)/mammalian target of rapamycin (mTOR) signaling pathway is thought to play a critical role in the regulation of protein synthesis and skeletal muscle mass. The purpose of the present study was to determine the effects of voluntary wheel running on the PKB/mTOR signaling pathway in muscles from aged mice (20-22 months). The total levels of mTOR were 65% higher in gastrocnemius muscles from aged mice subjected to wheel running compared to aged sedentary mice (p-0.002) PKB phosphorlation on Ser473 was 45% higher in gastrocnemius muscles from aged mice subjected to wheel running compared to aged sedentary mice (p=0.01) The total abundance of PKB was 50% higher in gastrocnemius muscles from wheel running mice compared to aged controls (p=0.005). Three months of wheel running did not alter the total amount of p70 S6K in gastrocnemius muscle. Protein synthesis, as assessed by [(14)C]phenylalanine incorporation into protein was significantly higher in soleus muscles from aged mice subjected to wheel running compared to aged sedentary mice (p-0.001) These findings indicate the aerobic exercise training may attenuate the age-related decline in protein synthesis, a process that appears to be due, in part, to increases in mTOR and PKB.
authors.affiliation: Department of Internal Medicine, Division of Geriatric Medicine, University of Michigan and the GRECC, Ann Arbor Veterans Affairs Healthcare System, Ann Arbor, MI, USA. treynolds@ithaca.edu
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Reynolds
authors.forename: Pamela
authors.initials: P
authors.lastname: Reid
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Larkin
authors.forename: Donald R
authors.initials: DR
authors.lastname: Dengel
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009119:Muscle Contraction / Q000502:physiology; D009124:Muscle Proteins / Q000096:biosynthesis; D018482:Muscle, Skeletal / Q000378:metabolism*; D010805:Physical Conditioning, Animal; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction / Q000502:physiology*; D020123:Sirolimus / Q000378:metabolism*; D013047:Specific Pathogen-Free Organisms
chemical_list: D009124:Muscle Proteins; D011518:Proto-Oncogene Proteins; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D020123:Sirolimus