Effects of aerobic exercise training on the protein kinase B (PKB)/mammalian target of rapamycin (mTOR) signaling pathway in aged skeletal muscle

• Published in: Experimental gerontology Vol. 39; no. 3; pp. 379 - 385
• Main Authors: Reynolds, Thomas H, Reid, Pamela, Larkin, Lisa M, Dengel, Donald R
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 01.03.2004
• Subjects: Aging - physiology; Animals; Contractile activity; Male; Mice; Mice, Inbred Strains; mRNA translation; Muscle Contraction - physiology; Muscle Proteins - biosynthesis; Muscle, Skeletal - metabolism; Physical Conditioning, Animal; Protein synthesis; Protein-Serine-Threonine Kinases - metabolism; Proto-Oncogene Proteins - metabolism; Proto-Oncogene Proteins c-akt; Signal Transduction - physiology; Sirolimus - metabolism; Specific Pathogen-Free Organisms; Voluntary wheel running; mRNA translation; Protein synthesis; Voluntary wheel running; Contractile activity
• ISSN: 0531-5565; 1873-6815
• DOI: 10.1016/j.exger.2003.12.005

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=0.02). 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=0.05). Three months of wheel running did not alter the total amount of p70 S6K in gastrocnemius muscle. Protein synthesis, as assessed by [ 14C]phenylalanine incorporation into protein was significantly higher in soleus muscles from aged mice subjected to wheel running compared to aged sedentary mice ( p=0.01). 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.