Effects of chronic overload on muscle hypertrophy and mTOR signaling in young adult and aged rats.
We examined the effect of 28 days of overload on mammalian target of rapamycin (mTOR) and extracellular signal-regulated kinase (ERK) signaling in young adult (Y; 6-month old) and aged (O; 30-month old) Fischer 344 x Brown Norway rats subjected to bilateral synergist ablation (SA) of two thirds of the gastrocnemius muscle or sham surgery (CON). Although plantaris (PLA) muscle hypertrophy was attenuated by aging, mTOR phosphorylation was 44% and 35% greater in Y SA and O SA compared with CON (p = .038). Ribosomal protein S6 phosphorylation was 114% and 24% higher in Y SA and O SA compared with CON (p = .009). Eukaryotic initiation factor 2Bepsilon phosphorylation was 33% and 9% higher in Y SA and O SA compared with CON (p = .04). Translational signaling in young adult and aged plantaris muscle is equally responsive to chronic overload.
Chalé-Rush
Angela
A
Nutrition, Exercise Physiology and Sarcopenia Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, 711 Washington Street, Boston, MA 02111, USA.
Morris
Evan P
EP
Kendall
Tracee L
TL
Brooks
Naomi E
NE
Fielding
Roger A
RA
D000367:Age Factors; D000375:Aging / Q000378:metabolism / Q000502:physiology; D000704:Analysis of Variance; D000818:Animals; D002908:Chronic Disease; D004195:Disease Models, Animal; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism*; D006984:Hypertrophy / Q000378:metabolism; D015151:Immunoblotting; D016014:Linear Models; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology*; D009929:Organ Size; D010766:Phosphorylation / Q000502:physiology; D011336:Probability; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D011897:Random Allocation; D051381:Rats; D011914:Rats, Inbred BN; D011916:Rats, Inbred F344; D015398:Signal Transduction; D020123:Sirolimus / Q000494:pharmacology*; D058570:TOR Serine-Threonine Kinases
D011494:Protein Kinases; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D020928:Mitogen-Activated Protein Kinases; D020123:Sirolimus