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.
Bibliographical noteFunding Information:
THR was supported by an Institutional National Research Service Award (T32-AG00114, ‘Multidisciplinary Research Training in Aging’) and a Time Release Grant from Ithaca College. DRD was supported by a Department of Veteran Affairs VA Merit Award and LML was supported by KO1-AG00710 from the National Institutes of Health. This work was also supported by the University of Michigan Geriatrics Center and University of Michigan Claude D. Pepper Older American Independence Center. The authors are indebted to the support of Dr John C. Lawrence Jr., Departments of Pharmacology and Medicine, University of Virginia, Charlottesville, VA.
- Contractile activity
- Protein synthesis
- Voluntary wheel running
- mRNA translation