title: Hypertrophy-Promoting Effects of Leucine Supplementation and Moderate Intensity Aerobic Exercise in Pre-Senescent Mice.
abstract: Several studies have indicated a positive influence of leucine supplementation and aerobic training on the aging skeletal muscle signaling pathways that control muscle protein balance and muscle remodeling. However, the effect of a combined intervention requires further clarification. Thirteen month old CD-1(®) mice were subjected to moderate aerobic exercise (45 min swimming per day with 3% body weight workload) and fed a chow diet with 5% leucine or 3.4% alanine for 8 weeks. Serum and plasma were prepared for glucose, urea nitrogen, insulin and amino acid profile analysis. The white gastrocnemius muscles were used for determination of muscle size and signaling proteins involved in protein synthesis and degradation. The results show that both 8 weeks of leucine supplementation and aerobic training elevated the activity of mTOR (mammalian target of rapamycin) and its downstream target p70S6K and 4E-BP1, inhibited the ubiquitin-proteasome system, and increased fiber cross-sectional area (CSA) in white gastrocnemius muscle. Moreover, leucine supplementation in combination with exercise demonstrated more significant effects, such as greater CSA, protein content and altered phosphorylation (suggestive of increased activity) of protein synthesis signaling proteins, in addition to lower expression of proteins involved in protein degradation compared to leucine or exercise alone. The current study shows moderate aerobic training combined with 5% leucine supplementation has the potential to increase muscle size in fast-twitch skeletal muscle during aging, potentially through increased protein synthesis and decreased protein breakdown.
authors.affiliation: Exercise Physiology and Biochemistry Laboratory, College of Physical Education, Jinggangshan University, Ji'an 343009, China. zhixia.ep@hotmail.com.|Exercise Intervention and Health Promotion Hubei Province Synergy Innovation Center, Wuhan Sports University, Wuhan 430079, China. zhixia.ep@hotmail.com.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Xia
authors.affiliation: Department of Kinesiology, Coastal Carolina University, Conway, SC 29528-6054, USA. jcholewa@coastal.edu.
authors.forename: Jason
authors.initials: J
authors.lastname: Cholewa
authors.affiliation: Exercise Physiology and Biochemistry Laboratory, College of Physical Education, Jinggangshan University, Ji'an 343009, China. baihu0098@163.com.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Exercise Intervention and Health Promotion Hubei Province Synergy Innovation Center, Wuhan Sports University, Wuhan 430079, China. yangyueqin226@163.com.
authors.forename: Yue-Qin
authors.initials: YQ
authors.lastname: Yang
authors.affiliation: Exercise Physiology Laboratory, Department of Exercise Physiology, Beijing Sport University, Beijing 100084, China. santanasan@163.com.
authors.forename: Hua-Yu
authors.initials: HY
authors.lastname: Shang
authors.affiliation: Muscle Physiology and Human Performance Research Group, Center of Physical Education and Sports, Federal University of Espirito Santo, Vitória/ES 29075-810, Brazil. lgtrainer@yahoo.com.br.
authors.forename: Lucas
authors.initials: L
authors.lastname: Guimarães-Ferreira
authors.affiliation: Division of Exercise Physiology, West Virginia University School of Medicine, Morgantown, WV 26506-9227, USA. man03e@my.fsu.edu.
authors.forename: Marshall Alan
authors.initials: MA
authors.lastname: Naimo
authors.affiliation: Department of Sports Medicine, Chengdu Sport University, Chengdu 610041, China. sqs111@126.com.
authors.forename: Quan-Sheng
authors.initials: QS
authors.lastname: Su
authors.affiliation: Department of Physical Education, Federal University of Maranhão (UFMA), São Luís-MA 65020-070, Brazil. neloz@ig.com.br.|Laboratory of Cellular and Molecular Biology of Skeletal Muscle (LABCEMME), São Luís-MA 65020-070, Brazil. neloz@ig.com.br.
authors.forename: Nelo Eidy
authors.initials: NE
authors.lastname: Zanchi
mesh_terms: D000375:Aging / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D004032:Diet; D019587:Dietary Supplements; D007930:Leucine / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D051379:Mice; D018482:Muscle, Skeletal / Q000187:drug effects / Q000502:physiology*; D010805:Physical Conditioning, Animal / Q000502:physiology*
chemical_list: D007930:Leucine
keywords: aerobic exercise; aging; leucine-rich diet; protein metabolism