Differential effects of leucine supplementation in young and aged mice at the onset of skeletal muscle regeneration.
Aging decreases the ability of skeletal muscle to respond to injury. Leucine has been demonstrated to target protein synthetic pathways in skeletal muscle thereby enhancing this response. However, the effect of aging on leucine-induced alterations in protein synthesis at the onset of skeletal muscle regeneration has not been fully elucidated. The purpose of this study was to determine if aging alters skeletal muscle regeneration and leucine-induced alterations in markers of protein synthesis. The tibialis anterior of young (3 months) and aged (24 months) female C57BL/6J mice were injected with either bupivacaine or PBS, and the mice were given ad libitum access to leucine-supplemented or normal drinking water. Protein and gene expression of markers of protein synthesis and degradation, respectively, were analyzed at three days post-injection. Following injury in young mice, leucine supplementation was observed to elevate only p-p70S6K. In aged mice, leucine was shown to elicit higher p-mTOR content with and without injury, and p-4EBP-1 content post-injury. Additionally in aged mice, leucine was shown to elicit higher content of relative p70S6K post-injury. Our study shows that leucine supplementation affects markers of protein synthesis at the onset of skeletal muscle regeneration differentially in young and aged mice.
Exercise Muscle Biology Laboratory, Department of Health, Human Performance and Recreation, University of Arkansas, Fayetteville, AR 72701, United States.
Richard A
RA
Perry
Exercise Muscle Biology Laboratory, Department of Health, Human Performance and Recreation, University of Arkansas, Fayetteville, AR 72701, United States.
Lemuel A
LA
Brown
Integrative Muscle Metabolism Laboratory, Human Performance Laboratory, Department of Health, Human Performance and Recreation, University of Arkansas, Fayetteville, AR 72701, United States.
David E
DE
Lee
Integrative Muscle Metabolism Laboratory, Human Performance Laboratory, Department of Health, Human Performance and Recreation, University of Arkansas, Fayetteville, AR 72701, United States.
Jacob L
JL
Brown
Department of Food Science, University of Arkansas, Fayetteville AR 72701, United States.
Jamie I
JI
Baum
Integrative Muscle Metabolism Laboratory, Human Performance Laboratory, Department of Health, Human Performance and Recreation, University of Arkansas, Fayetteville, AR 72701, United States.
Nicholas P
NP
Greene
Exercise Muscle Biology Laboratory, Department of Health, Human Performance and Recreation, University of Arkansas, Fayetteville, AR 72701, United States. Electronic address: tawashin@uark.edu.
Tyrone A
TA
Washington
D000375:Aging / Q000187:drug effects*; D000818:Animals; D002045:Bupivacaine / Q000494:pharmacology; D007930:Leucine / Q000494:pharmacology*; D051379:Mice; D018482:Muscle, Skeletal / Q000293:injuries / Q000502:physiology*; D012038:Regeneration / Q000187:drug effects*
D007930:Leucine; D002045:Bupivacaine
Aging; BCAAs; Injury; Protein synthesis; mTOR