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George A, Holderread BM, Lambert BS, Harris JD, McCulloch PC. Post-operative protein supplementation following orthopaedic surgery: A systematic review. SPORTS MEDICINE AND HEALTH SCIENCE 2024; 6:16-24. [PMID: 38463662 PMCID: PMC10918348 DOI: 10.1016/j.smhs.2023.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 08/30/2023] [Accepted: 08/31/2023] [Indexed: 03/12/2024] Open
Abstract
Decreased mechanical loading after orthopaedic surgery predisposes patients to develop muscle atrophy. The purpose of this review was to assess whether the evidence supports oral protein supplementation can help decrease postoperative muscle atrophy and/or improve patient outcomes following orthopaedic surgery. A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). PubMed (MEDLINE), Embase, Scopus, and Web of Science were searched for randomized controlled trials that assessed protein or amino acid supplementation in patients undergoing orthopaedic surgery. Two investigators independently conducted the search using relevant Boolean operations. Primary outcomes included functional or physiologic measures of muscle atrophy or strength. Fourteen studies including 611 patients (224 males, 387 females) were analyzed. Three studies evaluated protein supplementation after ACL reconstruction (ACLR), 3 after total hip arthroplasty (THA), 5 after total knee arthroplasty (TKA), and 3 after surgical treatment of hip fracture. Protein supplementation showed beneficial effects across all types of surgery. The primary benefit was a decrease in muscle atrophy compared to placebo as measured by muscle cross sectional area. Multiple authors also demonstrated improved functional measures and quicker achievement of rehabilitation benchmarks. Protein supplementation has beneficial effects on mitigating muscle atrophy in the postoperative period following ACLR, THA, TKA, and surgical treatment of hip fracture. These effects often correlate with improved functional measures and quicker achievement of rehabilitation benchmarks. Further research is needed to evaluate long-term effects of protein supplementation and to establish standardized population-specific regimens that maximize treatment efficacy in the postoperative period.
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Affiliation(s)
- Andrew George
- Houston Methodist Orthopedics and Sports Medicine, 6445 Main Street Suite 2300, Houston, TX, 77030, USA
| | - Brendan M. Holderread
- Houston Methodist Orthopedics and Sports Medicine, 6445 Main Street Suite 2300, Houston, TX, 77030, USA
| | - Bradley S. Lambert
- Houston Methodist Orthopedics and Sports Medicine, 6445 Main Street Suite 2300, Houston, TX, 77030, USA
- Houston Methodist Orthopedic Biomechanics Research Laboratory, 6670 Bertner Ave, Houston, TX, 77030, USA
| | - Joshua D. Harris
- Houston Methodist Orthopedics and Sports Medicine, 6445 Main Street Suite 2300, Houston, TX, 77030, USA
| | - Patrick C. McCulloch
- Houston Methodist Orthopedics and Sports Medicine, 6445 Main Street Suite 2300, Houston, TX, 77030, USA
- Houston Methodist Orthopedic Biomechanics Research Laboratory, 6670 Bertner Ave, Houston, TX, 77030, USA
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Hinkle JS, Rivera CN, Vaughan RA. Branched-Chain Amino Acids and Mitochondrial Biogenesis: An Overview and Mechanistic Summary. Mol Nutr Food Res 2022; 66:e2200109. [PMID: 36047448 PMCID: PMC9786258 DOI: 10.1002/mnfr.202200109] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 06/17/2022] [Indexed: 12/30/2022]
Abstract
Branched-chain amino acids (BCAA) are essential in the diet and promote several vital cell responses which may have benefits for health and athletic performance, as well as disease prevention. While BCAA are well-known for their ability to stimulate muscle protein synthesis, their effects on cell energetics are also becoming well-documented, but these receive less attention. In this review, much of the current evidence demonstrating BCAA ability (as individual amino acids or as part of dietary mixtures) to alter regulators of cellular energetics with an emphasis on mitochondrial biogenesis and related signaling is highlighted. Several studies have shown, both in vitro and in vivo, that BCAA (either individual or as a mixture) may promote signaling associated with increased mitochondrial biogenesis including the upregulation of master regulator of mitochondrial biogenesis peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), as well as numerous downstream targets and related function. However, sparse data in humans and the difficulty of controlling variables associated with feeding studies leave the physiological relevance of these findings unclear. Future well-controlled diet studies will be needed to assess if BCAA consumption is associated with increased mitochondrial biogenesis and improved metabolic outcomes in healthy and/or diseased human populations.
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Affiliation(s)
- Jason S. Hinkle
- Department of Exercise ScienceHigh Point UniversityHigh PointNC27262‐3598USA
| | - Caroline N. Rivera
- Department of Exercise ScienceHigh Point UniversityHigh PointNC27262‐3598USA
| | - Roger A. Vaughan
- Department of Exercise ScienceHigh Point UniversityHigh PointNC27262‐3598USA
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NISHIKAWA A, NISHIKAWA A, KAMAJIRI N, OKADA K, IMAGITA H. The Effects of Branched-Chain Amino Acids on the Akt/mTOR Pathway and Nebulin Protein in Joint Fixation-Induced Muscle Atrophy. J Nutr Sci Vitaminol (Tokyo) 2022; 68:112-119. [DOI: 10.3177/jnsv.68.112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Protein Supplementation Enhances the Effects of Intermittent Loading on Skeletal Muscles by Activating the mTORC1 Signaling Pathway in a Rat Model of Disuse Atrophy. Nutrients 2020; 12:nu12092729. [PMID: 32906669 PMCID: PMC7551819 DOI: 10.3390/nu12092729] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/26/2020] [Accepted: 09/04/2020] [Indexed: 01/07/2023] Open
Abstract
Inactivity leads to skeletal muscle atrophy, whereas intermittent loading (IL) during hind limb unloading (HU) attenuates muscle atrophy. However, the combined effects of IL and protein supplementation on disuse muscle atrophy are unclear. Therefore, we investigated the effects of IL and a high-protein oral nutritional supplement (HP) during HU on skeletal muscle mass and protein synthesis/breakdown. Male F344 rats were assigned to the control (CON), 14-day HU (HU), IL during HU (HU + IL), and IL during HU followed by HP administration (2.6 g protein/kg/day; HU + IL + HP) groups. Soleus and gastrocnemius muscles were sampled 30 min after the last IL and HP supplementation. HU decreased relative soleus and gastrocnemius muscle masses. Relative muscle masses and p70 ribosomal protein S6 kinase/ribosomal protein S6 phosphorylation in soleus and gastrocnemius muscles were higher in the HU + IL group than the HU group and further higher in the HU + IL + HP group than the HU + IL group in gastrocnemius muscle. Therefore, protein administration plus IL effectively prevented skeletal muscle atrophy induced by disuse, potentially via enhanced activation of targets downstream of mammalian target of rapamycin complex 1 (mTORC1) signaling pathway.
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Regulation of Skeletal Muscle Function by Amino Acids. Nutrients 2020; 12:nu12010261. [PMID: 31963899 PMCID: PMC7019684 DOI: 10.3390/nu12010261] [Citation(s) in RCA: 96] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 01/09/2020] [Accepted: 01/16/2020] [Indexed: 12/30/2022] Open
Abstract
Amino acids are components of proteins that also exist free-form in the body; their functions can be divided into (1) nutritional, (2) sensory, and (3) biological regulatory roles. The skeletal muscle, which is the largest organ in the human body, representing ~40% of the total body weight, plays important roles in exercise, energy expenditure, and glucose/amino acid usage—processes that are modulated by various amino acids and their metabolites. In this review, we address the metabolism and function of amino acids in the skeletal muscle. The expression of PGC1α, a transcriptional coactivator, is increased in the skeletal muscle during exercise. PGC1α activates branched-chain amino acid (BCAA) metabolism and is used for energy in the tricarboxylic acid (TCA) cycle. Leucine, a BCAA, and its metabolite, β-hydroxy-β-methylbutyrate (HMB), both activate mammalian target of rapamycin complex 1 (mTORC1) and increase protein synthesis, but the mechanisms of activation appear to be different. The metabolite of valine (another BCAA), β-aminoisobutyric acid (BAIBA), is increased by exercise, is secreted by the skeletal muscle, and acts on other tissues, such as white adipose tissue, to increase energy expenditure. In addition, several amino acid-related molecules reportedly activate skeletal muscle function. Oral 5-aminolevulinic acid (ALA) supplementation can protect against mild hyperglycemia and help prevent type 2 diabetes. β-alanine levels are decreased in the skeletal muscles of aged mice. β-alanine supplementation increased the physical performance and improved the executive function induced by endurance exercise in middle-aged individuals. Further studies focusing on the effects of amino acids and their metabolites on skeletal muscle function will provide data essential for the production of food supplements for older adults, athletes, and individuals with metabolic diseases.
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mTORC1 and PKB/Akt control the muscle response to denervation by regulating autophagy and HDAC4. Nat Commun 2019; 10:3187. [PMID: 31320633 PMCID: PMC6639401 DOI: 10.1038/s41467-019-11227-4] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 07/02/2019] [Indexed: 12/13/2022] Open
Abstract
Loss of innervation of skeletal muscle is a determinant event in several muscle diseases. Although several effectors have been identified, the pathways controlling the integrated muscle response to denervation remain largely unknown. Here, we demonstrate that PKB/Akt and mTORC1 play important roles in regulating muscle homeostasis and maintaining neuromuscular endplates after nerve injury. To allow dynamic changes in autophagy, mTORC1 activation must be tightly balanced following denervation. Acutely activating or inhibiting mTORC1 impairs autophagy regulation and alters homeostasis in denervated muscle. Importantly, PKB/Akt inhibition, conferred by sustained mTORC1 activation, abrogates denervation-induced synaptic remodeling and causes neuromuscular endplate degeneration. We establish that PKB/Akt activation promotes the nuclear import of HDAC4 and is thereby required for epigenetic changes and synaptic gene up-regulation upon denervation. Hence, our study unveils yet-unknown functions of PKB/Akt-mTORC1 signaling in the muscle response to nerve injury, with important implications for neuromuscular integrity in various pathological conditions. Denervation leads to muscle atrophy and neuromuscular endplate remodeling. Here, the authors show that a balanced activation of mTORC1 contributes to the dynamic regulation of autophagic flux in denervated muscle and that activation of PKB/Akt promotes the nuclear import of HDAC4, which is essential for endplate maintenance upon nerve injury
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GCN2 deficiency protects mice from denervation-induced skeletal muscle atrophy via inhibiting FoxO3a nuclear translocation. Protein Cell 2019; 9:966-970. [PMID: 29349768 PMCID: PMC6208481 DOI: 10.1007/s13238-018-0504-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
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Leucine promotes differentiation of porcine myoblasts through the protein kinase B (Akt)/Forkhead box O1 signalling pathway. Br J Nutr 2019; 119:727-733. [PMID: 29569540 DOI: 10.1017/s0007114518000181] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Leucine, one of the branched-chain amino acids, is the only amino acid to regulate protein turnover in skeletal muscle. Leucine not only increases muscle protein synthesis, but also decreases muscle protein degradation. It is well documented that leucine plays a positive role in differentiation of murine muscle cells. However, the role of leucine on porcine myoblast differentiation and its mechanism remains unclear. In this study, porcine myoblasts were induced to differentiate with differentiation medium containing different concentrations of leucine, and wortmannin was used to interdict the activity of protein kinase B (Akt). We found that leucine increased the number of myosin heavy chain-positive cells and creatine kinase activity. Moreover, leucine increased the mRNA and protein levels of myogenin and myogenic determining factor (MyoD). In addition, leucine increased the levels of phosphorylated Akt/Akt and phosphorylated Forkhead box O1 (P-FoxO1)/FoxO1, as well as decreased the protein level of FoxO1. However, wortmannin, a specific repressor of PI3K/Akt signalling pathway, attenuated the positive role of leucine on porcine myoblast differentiation. Our results suggest that leucine promotes porcine myoblast differentiation through the Akt/FoxO1 signalling pathway.
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The Role of AMPK in the Regulation of Skeletal Muscle Size, Hypertrophy, and Regeneration. Int J Mol Sci 2018; 19:ijms19103125. [PMID: 30314396 PMCID: PMC6212977 DOI: 10.3390/ijms19103125] [Citation(s) in RCA: 127] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 10/08/2018] [Accepted: 10/09/2018] [Indexed: 12/22/2022] Open
Abstract
AMPK (5’-adenosine monophosphate-activated protein kinase) is heavily involved in skeletal muscle metabolic control through its regulation of many downstream targets. Because of their effects on anabolic and catabolic cellular processes, AMPK plays an important role in the control of skeletal muscle development and growth. In this review, the effects of AMPK signaling, and those of its upstream activator, liver kinase B1 (LKB1), on skeletal muscle growth and atrophy are reviewed. The effect of AMPK activity on satellite cell-mediated muscle growth and regeneration after injury is also reviewed. Together, the current data indicate that AMPK does play an important role in regulating muscle mass and regeneration, with AMPKα1 playing a prominent role in stimulating anabolism and in regulating satellite cell dynamics during regeneration, and AMPKα2 playing a potentially more important role in regulating muscle degradation during atrophy.
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Friedrich O, Diermeier S, Larsson L. Weak by the machines: muscle motor protein dysfunction - a side effect of intensive care unit treatment. Acta Physiol (Oxf) 2018; 222. [PMID: 28387014 DOI: 10.1111/apha.12885] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 03/12/2017] [Accepted: 04/04/2017] [Indexed: 12/25/2022]
Abstract
Intensive care interventions involve periods of mechanical ventilation, sedation and complete mechanical silencing of patients. Critical illness myopathy (CIM) is an ICU-acquired myopathy that is associated with limb muscle weakness, muscle atrophy, electrical silencing of muscle and motor proteinopathy. The hallmark of CIM is a preferential muscle myosin loss due to increased catabolic and reduced anabolic activity. The ubiquitin proteasome pathway plays an important role, apart from recently identified novel mechanisms affecting non-lysosomal protein degradation or autophagy. CIM is not reproduced by pure disuse atrophy, denervation atrophy, steroid-induced atrophy or septic myopathy, although combinations of high-dose steroids and denervation can mimic CIM. New animal models of critical illness and ICU treatment (i.e. mechanical ventilation and complete immobilization) provide novel insights regarding the time course of protein synthesis and degradation alterations, and the role of protective chaperone activities in the process of myosin loss. Altered mechano-signalling seems involved in triggering a major part of myosin loss in experimental CIM models, and passive loading of muscle potently ameliorates the CIM phenotype. We provide a systematic overview of similarities and distinct differences in the signalling pathways involved in triggering muscle atrophy in CIM and isolated trigger factors. As preferential myosin loss is mostly determined from biochemistry analyses providing no spatial resolution of myosin loss processes within myofibres, we also provide first results monitoring myosin signal intensities during experimental ICU intervention using multi-photon Second Harmonic Generation microscopy. Our results confirm that myosin loss is an evenly distributed process within myofibres rather than being confined to hot spots.
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Affiliation(s)
- O. Friedrich
- Institute of Medical Biotechnology; Friedrich-Alexander-University Erlangen-Nürnberg; Erlangen Germany
- Erlangen Graduate School in Advanced Optical Technologie (SAOT); Friedrich-Alexander-University Erlangen-Nürnberg; Erlangen Germany
| | - S. Diermeier
- Institute of Medical Biotechnology; Friedrich-Alexander-University Erlangen-Nürnberg; Erlangen Germany
- Erlangen Graduate School in Advanced Optical Technologie (SAOT); Friedrich-Alexander-University Erlangen-Nürnberg; Erlangen Germany
| | - L. Larsson
- Department of Physiology & Pharmacology; Karolinska Institutet; Stockholm Sweden
- Section of Clinical Neurophysiology; Department of Clinical Neuroscience; Karolinska Institutet; Stockholm Sweden
- Department of Biobehavioral Health; The Pennsylvania State University; University Park PA USA
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Mitchell CJ, D'Souza RF, Mitchell SM, Figueiredo VC, Miller BF, Hamilton KL, Peelor FF, Coronet M, Pileggi CA, Durainayagam B, Fanning AC, Poppitt SD, Cameron-Smith D. Impact of dairy protein during limb immobilization and recovery on muscle size and protein synthesis; a randomized controlled trial. J Appl Physiol (1985) 2017; 124:717-728. [PMID: 29122965 DOI: 10.1152/japplphysiol.00803.2017] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Muscle disuse results in the loss of muscular strength and size, due to an imbalance between protein synthesis (MPS) and breakdown (MPB). Protein ingestion stimulates MPS, although it is not established if protein is able to attenuate muscle loss with immobilization (IM) or influence the recovery consisting of ambulatory movement followed by resistance training (RT). Thirty men (49.9 ± 0.6 yr) underwent 14 days of unilateral leg IM, 14 days of ambulatory recovery (AR), and a further six RT sessions over 14 days. Participants were randomized to consume an additional 20 g of dairy protein or placebo with a meal during the intervention. Isometric knee extension strength was reduced following IM (-24.7 ± 2.7%), partially recovered with AR (-8.6 ± 2.6%), and fully recovered after RT (-0.6 ± 3.4%), with no effect of supplementation. Thigh muscle cross-sectional area decreased with IM (-4.1 ± 0.5%), partially recovered with AR (-2.1 ± 0.5%), and increased above baseline with RT (+2.2 ± 0.5%), with no treatment effect. Myofibrillar MPS, measured using deuterated water, was unaltered by IM, with no effect of protein. During AR, MPS was increased only with protein supplementation. Protein supplementation did not attenuate the loss of muscle size and function with disuse or potentiate recovery but enhanced myofibrillar MPS during AR. NEW & NOTEWORTHY Twenty grams of daily protein supplementation does not attenuate the loss of muscle size and function induced by 2 wk of muscle disuse or potentiate recovery in middle-age men. Average mitochondrial but not myofibrillar muscle protein synthesis was attenuated during immobilization with no effect of supplementation. Protein supplementation increased myofibrillar protein synthesis during a 2-wk period of ambulatory recovery following disuse but without group differences in phenotype recovery.
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Affiliation(s)
| | - Randall F D'Souza
- Liggins Institute, The University of Auckland , Auckland , New Zealand
| | - Sarah M Mitchell
- Liggins Institute, The University of Auckland , Auckland , New Zealand
| | | | - Benjamin F Miller
- Department of Health and Exercise Science, Colorado State University , Fort Collins, Colorado
| | - Karyn L Hamilton
- Department of Health and Exercise Science, Colorado State University , Fort Collins, Colorado
| | - Fredrick F Peelor
- Department of Health and Exercise Science, Colorado State University , Fort Collins, Colorado
| | - Marcelli Coronet
- Liggins Institute, The University of Auckland , Auckland , New Zealand
| | - Chantal A Pileggi
- Liggins Institute, The University of Auckland , Auckland , New Zealand
| | | | - Aaron C Fanning
- Fonterra Research and Development Centre , Palmerston North , New Zealand
| | - Sally D Poppitt
- School of Biological Sciences, The University of Auckland , Auckland , New Zealand
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Leucine stimulates PPARβ/δ-dependent mitochondrial biogenesis and oxidative metabolism with enhanced GLUT4 content and glucose uptake in myotubes. Biochimie 2016; 128-129:1-7. [PMID: 27345255 DOI: 10.1016/j.biochi.2016.06.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 06/15/2016] [Indexed: 02/08/2023]
Abstract
Leucine stimulates anabolic and catabolic processes in skeletal muscle, however little is known about the effects of leucine on peroxisome proliferator-activated receptor (PPAR) activity. This work characterized the effects of 24-h leucine treatment on metabolic parameters and protein expression in cultured myotubes. Leucine significantly increased PPARβ/δ expression as well as markers of mitochondrial biogenesis, leading to significantly increased mitochondrial content and oxidative metabolism in a PPARβ/δ-dependent manner. However, leucine-treated cells did not display significant alterations in uncoupling protein expression or oxygen consumed per relative mitochondrial content suggesting leucine-mediated increases in oxidative metabolism are a function of increased mitochondrial content and not altered mitochondrial efficiency. Leucine treatment also increased GLUT4 content and glucose uptake as well as PPARγ and FAS expression leading to increased total lipid content. Leucine appears to activate PPAR activity leading to increased mitochondrial biogenesis and elevated substrate oxidation, while simultaneously promoting substrate/lipid storage and protein synthesis.
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13
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Leucine-induced anabolic-catabolism: two sides of the same coin. Amino Acids 2015; 48:321-36. [DOI: 10.1007/s00726-015-2109-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 09/28/2015] [Indexed: 10/22/2022]
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Sato T, Ito Y, Nagasawa T. Dietary L-Lysine Suppresses Autophagic Proteolysis and Stimulates Akt/mTOR Signaling in the Skeletal Muscle of Rats Fed a Low-Protein Diet. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2015; 63:8192-8198. [PMID: 26366928 DOI: 10.1021/acs.jafc.5b03811] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Amino acids, especially L-leucine, regulate protein turnover in skeletal muscle and have attracted attention as a means of increasing muscle mass in people suffering from malnutrition, aging (sarcopenia), or a bedridden state. We previously showed that oral administration of L-lysine (Lys) by gavage suppressed proteolysis in skeletal muscles of fasted rats. However, the intake of Lys in the absence of other dietary components is unlikely in a non-experimental setting, and other dietary components may interfere with the suppressive effect of Lys on proteolysis. We supplemented Lys to a 10% casein diet and investigated the effect of Lys on proteolysis and autophagy, a major proteolytic system, in the skeletal muscle of rats. The rate of proteolysis was evaluated from 3-methylhisitidine (MeHis) released from isolated muscles, in plasma, and excreted in urine. Supplementing lysine with the 10% casein diet decreased the rate of proteolysis induced by intake of a low-protein diet. The upregulated autophagy activity [light chain 3 (LC3)-II/total LC3] caused by a low-protein diet was reduced, and the Akt/mTOR signaling pathway was activated by Lys. Importantly, continuous feeding of a Lys-rich 10% casein diet for 15 days increased the masses of the soleus and gastrocnemius muscles. Taken together, supplementation of Lys to a low-protein diet suppresses autophagic proteolysis through the Akt/mTOR signaling pathway, and continuous feeding of a Lys-rich diet may increase skeletal muscle mass.
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Affiliation(s)
- Tomonori Sato
- Department of Bioresources Science, The United Graduate School of Agricultural Sciences, and ‡Department of Biological Chemistry and Food Science, Graduate School of Agriculture, Iwate University , Morioka, Iwate 020-8550, Japan
| | - Yoshiaki Ito
- Department of Bioresources Science, The United Graduate School of Agricultural Sciences, and ‡Department of Biological Chemistry and Food Science, Graduate School of Agriculture, Iwate University , Morioka, Iwate 020-8550, Japan
| | - Takashi Nagasawa
- Department of Bioresources Science, The United Graduate School of Agricultural Sciences, and ‡Department of Biological Chemistry and Food Science, Graduate School of Agriculture, Iwate University , Morioka, Iwate 020-8550, Japan
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Jang J, Yun HY, Park J, Lim K. Protective effect of branched chain amino acids on hindlimb suspension-induced muscle atrophy in growing rats. J Exerc Nutrition Biochem 2015; 19:183-9. [PMID: 26527098 PMCID: PMC4624119 DOI: 10.5717/jenb.2015.15062704] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 06/08/2015] [Accepted: 06/27/2015] [Indexed: 11/04/2022] Open
Abstract
PURPOSE The effect of BCAA (branched chain amino acid) administration on muscle atrophy during growth phases is not well known. We investigated whether BCAA administration can prevent the muscle atrophy induced by hindlimb suspension in growing male rats. METHODS Male Wistar rats were assigned to 1 of 2 groups (n = 7/group): hindlimb suspension and hindlimb suspension with oral BCAA administration (600 mg·kg(-1)·day(-1), valine 1: leucine 2: isoleucine 1). After 14 days of hindlimb suspension, the weight and mRNA levels of the soleus muscle were measured. RESULTS BCAA administration prevented a decrease in soleus muscle weight. BCAA administration attenuated atrogin-1 and MuRF1 mRNA expression, which has been reported to play a pivotal role in muscle atrophy. CONCLUSION BCAA could serve as an effective supplement for the prevention or treatment of muscle atrophy, especially atrophy caused by weightlessness.
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Affiliation(s)
- Jiwoong Jang
- Laboratory of Exercise Nutrition, Department of Physical Education, Konkuk University, Seoul, Republic of Korea
| | - Hea-Yeon Yun
- Physical Activity and Performance Institute (PAPI), Konkuk University, Seoul, Republic of Korea
| | - Jonghoon Park
- Laboratory of Exercise Nutrition, Department of Physical Education, Konkuk University, Seoul, Republic of Korea ; Physical Activity and Performance Institute (PAPI), Konkuk University, Seoul, Republic of Korea
| | - Kiwon Lim
- Laboratory of Exercise Nutrition, Department of Physical Education, Konkuk University, Seoul, Republic of Korea ; Physical Activity and Performance Institute (PAPI), Konkuk University, Seoul, Republic of Korea
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