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Salvador AF, McKenna CF, Paulussen KJM, Keeble AR, Askow AT, Fang HY, Li Z, Ulanov AV, Paluska SA, Moore DR, Burd NA. Early resistance training-mediated stimulation of daily muscle protein synthetic responses to higher habitual protein intake in middle-aged adults. J Physiol 2021; 599:4287-4307. [PMID: 34320223 DOI: 10.1113/jp281907] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 07/26/2021] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The ingestion of protein potentiates the stimulation of myofibrillar protein synthesis rates after an acute bout of resistance exercise. Protein supplementation (eating above the protein Recommended Dietary Allowance) during resistance training has been shown to maximize lean mass and strength gains in healthy young and older adults. Here, contractile, oxidative, and structural protein synthesis were assessed in skeletal muscle in response to a moderate or higher protein diet during the early adaptive phase of resistance training in middle-aged adults. The stimulation of myofibrillar, mitochondrial or collagen protein synthesis rates during 0-3 weeks of resistance training is not further enhanced by a higher protein diet. These results show that moderate protein diets are sufficient to support the skeletal muscle adaptive response during the early phase of a resistance training programme. ABSTRACT Protein ingestion augments muscle protein synthesis (MPS) rates acutely after resistance exercise and can offset age-related loss in muscle mass. Skeletal muscle contains a variety of protein pools, such as myofibrillar (contractile), mitochondrial (substrate oxidation), and collagen (structural support) proteins, and the sensitivity to nutrition and exercise seems to be dependent on the major protein fraction studied. However, it is unknown how free-living conditions with high dietary protein density and habitual resistance exercise mediates muscle protein subfraction synthesis. Therefore, we investigated the effect of moderate (MOD: 1.06 ± 0.22 g kg-1 day-1 ) or high (HIGH: 1.55 ± 0.25 g kg-1 day-1 ) protein intake on daily MPS rates within the myofibrillar (MyoPS), mitochondrial (MitoPS) and collagen (CPS) protein fractions in middle-aged men and women (n = 20, 47 ± 1 years, BMI 28 ± 1 kg m-2 ) during the early phase (0-3 weeks) of a dietary counselling-controlled resistance training programme. Participants were loaded with deuterated water, followed by daily maintenance doses throughout the intervention. Muscle biopsies were collected at baseline and after weeks 1, 2 and 3. MyoPS in the HIGH condition remained constant (P = 1.000), but MOD decreased over time (P = 0.023). MitoPS decreased after 0-3 weeks when compared to 0-1 week (P = 0.010) with no effects of protein intake (P = 0.827). A similar decline with no difference between groups (P = 0.323) was also observed for CPS (P = 0.007). Our results demonstrated that additional protein intake above moderate amounts does not potentiate the stimulation of longer-term MPS responses during the early stage of resistance training adaptations in middle-aged adults.
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Affiliation(s)
- Amadeo F Salvador
- Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Colleen F McKenna
- Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Kevin J M Paulussen
- Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Alexander R Keeble
- Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Andrew T Askow
- Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Hsin-Yu Fang
- Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Zhong Li
- Roy J. Carver Biotechnology Center, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Alexander V Ulanov
- Roy J. Carver Biotechnology Center, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Scott A Paluska
- Department of Family Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Daniel R Moore
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada
| | - Nicholas A Burd
- Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, IL, USA.,Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, USA
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52
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The effects of glucagon and the target of rapamycin (TOR) on skeletal muscle protein synthesis and age-dependent sarcopenia in humans. Clin Nutr ESPEN 2021; 44:15-25. [PMID: 34330459 DOI: 10.1016/j.clnesp.2021.06.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 06/21/2021] [Indexed: 01/07/2023]
Abstract
BACKGROUND AND AIMS Human target of rapamycin (TOR) is a kinase that stimulates protein synthesis in the skeletal muscle in response to amino acids and physical activity. METHODS A comprehensive literature search was conducted on the PubMed database from its inception up to May 2021 to retrieve information on the effects of TOR and glucagon on muscle function. Articles written in English regarding human subjects were included. RESULTS l-leucine activates TOR to initiate protein synthesis in the skeletal muscle. Glucagon has a crucial role suppressing skeletal muscle protein synthesis by increasing l-leucine oxidation and the irreversible loss of this amino acid. Glucagon-induced l-leucine oxidation suppresses TOR and attenuates the ability of skeletal muscle to synthesize proteins. Conditions associated with increased glucagon secretion typically feature reduced ability to synthesize proteins in the skeletal muscle that may evolve into sarcopenia. Animal protein ingestion, unlike vegetable protein, stimulates glucagon secretion. High intake of animal protein increases l-leucine oxidation and promotes the use of amino acids as fuel. Sarcopenia and arterial stiffness characteristically occur together in conditions featuring insulin resistance, such as aging. Insulin resistance mediates the relationship between aging and sarcopenia and arterial stiffness. The loss of skeletal muscle fibers that characterizes sarcopenia is followed by collagen and lipid accumulation. Likewise, insulin resistance is associated with arterial stiffness and intima-media thickening due to adaptive accretion of collagen and lipids in the arterial wall. CONCLUSIONS Human TOR participates in the pathogenesis of sarcopenia and arterial stiffness, although its effects remain to be fully elucidated.
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Gustafsson T, Ulfhake B. Sarcopenia: What Is the Origin of This Aging-Induced Disorder? Front Genet 2021; 12:688526. [PMID: 34276788 PMCID: PMC8285098 DOI: 10.3389/fgene.2021.688526] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 05/10/2021] [Indexed: 01/03/2023] Open
Abstract
We here review the loss of muscle function and mass (sarcopenia) in the framework of human healthspan and lifespan, and mechanisms involved in aging. The rapidly changing composition of the human population will impact the incidence and the prevalence of aging-induced disorders such as sarcopenia and, henceforth, efforts to narrow the gap between healthspan and lifespan should have top priority. There are substantial knowledge gaps in our understanding of aging. Heritability is estimated to account for only 25% of lifespan length. However, as we push the expected lifespan at birth toward those that we consider long-lived, the genetics of aging may become increasingly important. Linkage studies of genetic polymorphisms to both the susceptibility and aggressiveness of sarcopenia are still missing. Such information is needed to shed light on the large variability in clinical outcomes between individuals and why some respond to interventions while others do not. We here make a case for the concept that sarcopenia has a neurogenic origin and that in manifest sarcopenia, nerve and myofibers enter into a vicious cycle that will escalate the disease progression. We point to gaps in knowledge, for example the crosstalk between the motor axon, terminal Schwann cell, and myofiber in the denervation processes that leads to a loss of motor units and muscle weakness. Further, we argue that the operational definition of sarcopenia should be complemented with dynamic metrics that, along with validated biomarkers, may facilitate early preclinical diagnosis of individuals vulnerable to develop advanced sarcopenia. We argue that preventive measures are likely to be more effective to counter act aging-induced disorders than efforts to treat manifest clinical conditions. To achieve compliance with a prescription of preventive measures that may be life-long, we need to identify reliable predictors to design rational and convincing interventions.
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Affiliation(s)
- Thomas Gustafsson
- Division of Clinical Physiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Brun Ulfhake
- Division of Clinical Physiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
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McKendry J, Stokes T, Mcleod JC, Phillips SM. Resistance Exercise, Aging, Disuse, and Muscle Protein Metabolism. Compr Physiol 2021; 11:2249-2278. [PMID: 34190341 DOI: 10.1002/cphy.c200029] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Skeletal muscle is the organ of locomotion, its optimal function is critical for athletic performance, and is also important for health due to its contribution to resting metabolic rate and as a site for glucose uptake and storage. Numerous endogenous and exogenous factors influence muscle mass. Much of what is currently known regarding muscle protein turnover is owed to the development and use of stable isotope tracers. Skeletal muscle mass is determined by the meal- and contraction-induced alterations of muscle protein synthesis and muscle protein breakdown. Increased loading as resistance training is the most potent nonpharmacological strategy by which skeletal muscle mass can be increased. Conversely, aging (sarcopenia) and muscle disuse lead to the development of anabolic resistance and contribute to the loss of skeletal muscle mass. Nascent omics-based technologies have significantly improved our understanding surrounding the regulation of skeletal muscle mass at the gene, transcript, and protein levels. Despite significant advances surrounding the mechanistic intricacies that underpin changes in skeletal muscle mass, these processes are complex, and more work is certainly needed. In this article, we provide an overview of the importance of skeletal muscle, describe the influence that resistance training, aging, and disuse exert on muscle protein turnover and the molecular regulatory processes that contribute to changes in muscle protein abundance. © 2021 American Physiological Society. Compr Physiol 11:2249-2278, 2021.
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Affiliation(s)
- James McKendry
- Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Tanner Stokes
- Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Jonathan C Mcleod
- Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Stuart M Phillips
- Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
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Tao K, Duan Y, Wang H, Zeng D, Fang Z, Yan H, Lu Y. De novo Explorations of Sarcopenia via a Dynamic Model. Front Physiol 2021; 12:670381. [PMID: 34122142 PMCID: PMC8194405 DOI: 10.3389/fphys.2021.670381] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 05/07/2021] [Indexed: 12/17/2022] Open
Abstract
Background: The cause of sarcopenia has been observed over decades by clinical trials, which, however, are still insufficient to systematically unravel the enigma of how resistance exercise mediates skeletal muscle mass. Materials and Methods: Here, we proposed a minimal regulatory network and developed a dynamic model to rigorously investigate the mechanism of sarcopenia. Our model is consisted of eight ordinary differential equations and incorporates linear and Hill-function terms to describe positive and negative feedbacks between protein species, respectively. Results: A total of 720 samples with 10 scaled intensities were included in simulations, which revealed the expression level of AKT (maximum around 3.9-fold) and mTOR (maximum around 5.5-fold) at 3, 6, and 24 h at high intensity, and non-monotonic relation (ranging from 1.2-fold to 1.7-fold) between the graded intensities and skeletal muscle mass. Furthermore, continuous dynamics (within 24 h) of AKT, mTOR, and other proteins were obtained accordingly, and we also predicted the delaying effect with the median of maximized muscle mass shifting from 1.8-fold to 4.6-fold during a 4-fold increase of delay coefficient. Conclusion: The de novo modeling framework sheds light on the interdisciplinary methodology integrating computational approaches with experimental results, which facilitates the deeper understandings of exercise training and sarcopenia.
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Affiliation(s)
- Kuan Tao
- School of Sports Engineering, Beijing Sport University, Beijing, China
| | - Yushuang Duan
- School of Sport Medicine and Physical Therapy, Beijing Sport University, Beijing, China
| | - Huohuo Wang
- School of Sport Medicine and Physical Therapy, Beijing Sport University, Beijing, China
| | - Dan Zeng
- School of Sport Medicine and Physical Therapy, Beijing Sport University, Beijing, China
| | - Zilong Fang
- School of Sport Medicine and Physical Therapy, Beijing Sport University, Beijing, China
| | - Huiping Yan
- School of Sport Medicine and Physical Therapy, Beijing Sport University, Beijing, China
| | - Yifan Lu
- School of Sport Medicine and Physical Therapy, Beijing Sport University, Beijing, China.,Key Laboratory of Sports and Physical Fitness of the Ministry of Education, Beijing Sport University, Beijing, China
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56
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Sadria M, Layton AT. Interactions among mTORC, AMPK and SIRT: a computational model for cell energy balance and metabolism. Cell Commun Signal 2021; 19:57. [PMID: 34016143 PMCID: PMC8135154 DOI: 10.1186/s12964-021-00706-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 01/11/2021] [Indexed: 12/26/2022] Open
Abstract
Background Cells adapt their metabolism and activities in response to signals from their surroundings, and this ability is essential for their survival in the face of perturbations. In tissues a deficit of these mechanisms is commonly associated with cellular aging and diseases, such as cardiovascular disease, cancer, immune system decline, and neurological pathologies. Several proteins have been identified as being able to respond directly to energy, nutrient, and growth factor levels and stress stimuli in order to mediate adaptations in the cell. In particular, mTOR, AMPK, and sirtuins are known to play an essential role in the management of metabolic stress and energy balance in mammals. Methods To understand the complex interactions of these signalling pathways and environmental signals, and how those interactions may impact lifespan and health-span, we have developed a computational model of metabolic signalling pathways. Specifically, the model includes (i) the insulin/IGF-1 pathway, which couples energy and nutrient abundance to the execution of cell growth and division, (ii) mTORC1 and the amino acid sensors such as sestrin, (iii) the Preiss-Handler and salvage pathways, which regulate the metabolism of NAD+ and the NAD+ -consuming factor SIRT1, (iv) the energy sensor AMPK, and (v) transcription factors FOXO and PGC-1α. Results The model simulates the interactions among key regulators such as AKT, mTORC1, AMPK, NAD+ , and SIRT, and predicts their dynamics. Key findings include the clinically important role of PRAS40 and diet in mTORC1 inhibition, and a potential link between SIRT1-activating compounds and premature autophagy. Moreover, the model captures the exquisite interactions of leucine, sestrin2, and arginine, and the resulting signal to the mTORC1 pathway. These results can be leveraged in the development of novel treatment of cancers and other diseases. Conclusions This study presents a state-of-the-art computational model for investigating the interactions among signaling pathways and environmental stimuli in growth, ageing, metabolism, and diseases. The model can be used as an essential component to simulate gene manipulation, therapies (e.g., rapamycin and wortmannin), calorie restrictions, and chronic stress, and assess their functional implications on longevity and ageing‐related diseases. Video Abstract
Supplementary Information The online version contains supplementary material available at 10.1186/s12964-021-00706-1.
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Affiliation(s)
- Mehrshad Sadria
- Department of Applied Mathematics, University of Waterloo, Waterloo, ON, Canada.
| | - Anita T Layton
- Department of Applied Mathematics, University of Waterloo, Waterloo, ON, Canada.,Department of Biology, Cheriton School of Computer Science, and School of Pharmacy, University of Waterloo, Waterloo, ON, Canada
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57
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Paulussen KJM, McKenna CF, Beals JW, Wilund KR, Salvador AF, Burd NA. Anabolic Resistance of Muscle Protein Turnover Comes in Various Shapes and Sizes. Front Nutr 2021; 8:615849. [PMID: 34026802 PMCID: PMC8131552 DOI: 10.3389/fnut.2021.615849] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Accepted: 03/01/2021] [Indexed: 12/18/2022] Open
Abstract
Anabolic resistance is defined by a blunted stimulation of muscle protein synthesis rates (MPS) to common anabolic stimuli in skeletal muscle tissue such as dietary protein and exercise. Generally, MPS is the target of most exercise and feeding interventions as muscle protein breakdown rates seem to be less responsive to these stimuli. Ultimately, the blunted responsiveness of MPS to dietary protein and exercise underpins the loss of the amount and quality of skeletal muscle mass leading to decrements in physical performance in these populations. The increase of both habitual physical activity (including structured exercise that targets general fitness characteristics) and protein dense food ingestion are frontline strategies utilized to support muscle mass, performance, and health. In this paper, we discuss anabolic resistance as a common denominator underpinning muscle mass loss with aging, obesity, and other disease states. Namely, we discuss the fact that anabolic resistance exists as a dimmer switch, capable of varying from higher to lower levels of resistance, to the main anabolic stimuli of feeding and exercise depending on the population. Moreover, we review the evidence on whether increased physical activity and targeted exercise can be leveraged to restore the sensitivity of skeletal muscle tissue to dietary amino acids regardless of the population.
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Affiliation(s)
- Kevin J. M. Paulussen
- Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Colleen F. McKenna
- Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Joseph W. Beals
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO, United States
| | - Kenneth R. Wilund
- Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Amadeo F. Salvador
- Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Nicholas A. Burd
- Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States
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58
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Lee EJ, Neppl RL. Influence of Age on Skeletal Muscle Hypertrophy and Atrophy Signaling: Established Paradigms and Unexpected Links. Genes (Basel) 2021; 12:genes12050688. [PMID: 34063658 PMCID: PMC8147613 DOI: 10.3390/genes12050688] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 04/26/2021] [Accepted: 04/27/2021] [Indexed: 12/16/2022] Open
Abstract
Skeletal muscle atrophy in an inevitable occurrence with advancing age, and a consequence of disease including cancer. Muscle atrophy in the elderly is managed by a regimen of resistance exercise and increased protein intake. Understanding the signaling that regulates muscle mass may identify potential therapeutic targets for the prevention and reversal of muscle atrophy in metabolic and neuromuscular diseases. This review covers the major anabolic and catabolic pathways that regulate skeletal muscle mass, with a focus on recent progress and potential new players.
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59
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Van Pelt DW, Lawrence MM, Miller BF, Butterfield TA, Dupont-Versteegden EE. Massage as a Mechanotherapy for Skeletal Muscle. Exerc Sport Sci Rev 2021; 49:107-114. [PMID: 33720912 PMCID: PMC8320327 DOI: 10.1249/jes.0000000000000244] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Massage is anecdotally associated with many health benefits, but physiological and clinically relevant mechanisms recently have begun to be investigated in a controlled manner. Herein, we describe research supporting our hypothesis that massage can be used as a mechanotherapy imparting biologically relevant adaptations in skeletal muscle and improving muscle properties.
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Affiliation(s)
- Douglas W Van Pelt
- Department of Physical Therapy and Center for Muscle Biology, University of Kentucky, Lexington, KY
| | - Marcus M Lawrence
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK
| | - Benjamin F Miller
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK
| | - Timothy A Butterfield
- Department of Athletic Training and Clinical Nutrition and Center for Muscle Biology, University of Kentucky, Lexington, KY
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60
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Garg K, Mahmassani ZS, Dvoretskiy S, Valero MC, Huntsman HD, Lapp S, Wu YF, Hauschka SD, Burkin DJ, Boppart MD. Laminin-111 Improves the Anabolic Response to Mechanical Load in Aged Skeletal Muscle. J Gerontol A Biol Sci Med Sci 2021; 76:586-590. [PMID: 33284954 DOI: 10.1093/gerona/glaa308] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Indexed: 12/12/2022] Open
Abstract
Anabolic resistance to a mechanical stimulus may contribute to the loss of skeletal muscle mass observed with age. In this study, young and aged mice were injected with saline or human LM-111 (1 mg/kg). One week later, the myotendinous junction of the gastrocnemius muscle was removed via myotenectomy (MTE), thus placing a chronic mechanical stimulus on the remaining plantaris muscle for 2 weeks. LM-111 increased α7B integrin protein expression and clustering of the α7B integrin near DAPI+ nuclei in aged muscle in response to MTE. LM-111 reduced CD11b+ immune cells, enhanced repair, and improved the growth response to loading in aged plantaris muscle. These results suggest that LM-111 may represent a novel therapeutic approach to prevent and/or treat sarcopenia.
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Affiliation(s)
- Koyal Garg
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign
| | - Ziad S Mahmassani
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign.,Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign
| | - Svyatoslav Dvoretskiy
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign.,Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign
| | - M Carmen Valero
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign.,Institute for Genomic Biology, University of Illinois at Urbana-Champaign
| | - Heather D Huntsman
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign.,Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign
| | - Samuel Lapp
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign.,Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign
| | - Yu-Fu Wu
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign.,Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign
| | | | - Dean J Burkin
- Department of Pharmacology, University of Nevada School of Medicine, Reno
| | - Marni D Boppart
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign.,Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign.,Institute for Genomic Biology, University of Illinois at Urbana-Champaign
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61
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Watanabe K, Holobar A, Uchida K, Mita Y. Fish Protein Ingestion Induces Neural, but Not Muscular Adaptations, Following Resistance Training in Young Adults. Front Nutr 2021; 8:645747. [PMID: 33777994 PMCID: PMC7993090 DOI: 10.3389/fnut.2021.645747] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 02/18/2021] [Indexed: 11/13/2022] Open
Abstract
Purpose: Nutritional supplementation in conjunction with exercise is of interest for the prevention or improvement of declines in motor performances in older adults. An understanding of the effects on both young and older adults contributes to its effective application. We investigated the effect of fish protein ingestion with resistance training on neural and muscular adaptations in young adults using interventions and assessments that have already been tested in older adults. Methods: Eighteen young adults underwent 8 weeks of isometric knee extension training. During the intervention, nine participants ingested 5 g of fish protein (n = 9, Alaska pollack protein, APP), and the other nine participants ingested casein as a control (n = 9, CAS) in addition to daily meals. Before, during, and after the intervention, the isometric knee extension force, lower extremity muscle mass, and motor unit firing pattern of knee extensor muscles were measured. Results: Maximum voluntary contraction (MVC) was significantly increased in both APP and CAS groups from 0 weeks to 4, 6, and 8 weeks of intervention (p < 0.001), but there were no significant differences between the groups (p = 0.546–0.931). Muscle mass was not significantly changed during the intervention in either group (p = 0.250–0.698). Significant changes in motor unit firing rates (p = 0.02 and 0.029 for motor units recruited at 20–40% of MVC and at 40–60%) were observed following the intervention in the APP but not CAS (p = 0.120–0.751) group. Conclusions: These results suggest that dietary fish protein ingestion changes motor unit adaptations following resistance training in young adults.
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Affiliation(s)
- Kohei Watanabe
- Laboratory of Neuromuscular Biomechanics, Faculty of Liberal Arts and Sciences and School of International Liberal Studies, Chukyo University, Nagoya, Japan
| | - Aleš Holobar
- Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor, Slovenia
| | | | - Yukiko Mita
- Department of Human Nutrition, School of Life Studies, Sugiyama Jogakuen University, Nagoya, Japan
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62
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Dunlap KR, Steiner JL, Rossetti ML, Kimball SR, Gordon BS. A clinically relevant decrease in contractile force differentially regulates control of glucocorticoid receptor translocation in mouse skeletal muscle. J Appl Physiol (1985) 2021; 130:1052-1063. [PMID: 33600283 DOI: 10.1152/japplphysiol.01064.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Muscle atrophy decreases physical function and overall health. Increased glucocorticoid production and/or use of prescription glucocorticoids can significantly induce muscle atrophy by activating the glucocorticoid receptor, thereby transcribing genes that shift protein balance in favor of net protein degradation. Although mechanical overload can blunt glucocorticoid-induced atrophy in young muscle, those affected by glucocorticoids generally have impaired force generation. It is unknown whether contractile force alters the ability of resistance exercise to mitigate glucocorticoid receptor translocation and induce a desirable shift in protein balance when glucocorticoids are elevated. In the present study, mice were subjected to a single bout of unilateral, electrically induced muscle contractions by stimulating the sciatic nerve at 100 Hz or 50 Hz frequencies to elicit high or moderate force contractions of the tibialis anterior, respectively. Dexamethasone was used to activate the glucocorticoid receptor. Dexamethasone increased glucocorticoid signaling, including nuclear translocation of the receptor, but this was mitigated only by high force contractions. The ability of high force contractions to mitigate glucocorticoid receptor translocation coincided with a contraction-mediated increase in muscle protein synthesis, which did not occur in the dexamethasone-treated mice subjected to moderate force contractions. Though moderate force contractions failed to increase protein synthesis following dexamethasone treatment, both high and moderate force contractions blunted the glucocorticoid-mediated increase in LC3 II:I marker of autophagy. Thus, these data show that force generation is important for the ability of resistance exercise to mitigate glucocorticoid receptor translocation and promote a desirable shift in protein balance when glucocorticoids are elevated.NEW & NOTEWORTHY Glucocorticoids induce significant skeletal muscle atrophy by activating the glucocorticoid receptor. Our work shows that muscle contractile force dictates glucocorticoid receptor nuclear translocation. We also show that blunting nuclear translocation by high force contractions coincides with the ability of muscle to mount an anabolic response characterized by increased muscle protein synthesis. This work further defines the therapeutic parameters of skeletal muscle contractions to blunt glucocorticoid-induced atrophy.
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Affiliation(s)
- Kirsten R Dunlap
- Department of Nutrition, Food and Exercise Science, Florida State University, Tallahassee, Florida
| | - Jennifer L Steiner
- Department of Nutrition, Food and Exercise Science, Florida State University, Tallahassee, Florida.,Institute of Sports Sciences and Medicine, Florida State University, Tallahassee, Florida
| | - Michael L Rossetti
- Department of Nutrition, Food and Exercise Science, Florida State University, Tallahassee, Florida
| | - Scot R Kimball
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Bradley S Gordon
- Department of Nutrition, Food and Exercise Science, Florida State University, Tallahassee, Florida.,Institute of Sports Sciences and Medicine, Florida State University, Tallahassee, Florida
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Lawrence MM, Van Pelt DW, Confides AL, Hettinger ZR, Hunt ER, Reid JJ, Laurin JL, Peelor FF, Butterfield TA, Miller BF, Dupont-Versteegden EE. Muscle from aged rats is resistant to mechanotherapy during atrophy and reloading. GeroScience 2021; 43:65-83. [PMID: 32588343 PMCID: PMC8050124 DOI: 10.1007/s11357-020-00215-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 06/09/2020] [Indexed: 12/22/2022] Open
Abstract
Massage is a viable mechanotherapy to improve protein turnover during disuse atrophy and improve muscle regrowth during recovery from disuse atrophy in adult muscle. Therefore, we investigated whether massage can cause beneficial adaptations in skeletal muscle from aged rats during normal weight-bearing (WB) conditions, hindlimb suspension (HS), or reloading (RE) following HS. Aged (30 months) male Fischer 344/Brown Norway rats were divided into two experiments: (1) WB for 7 days (WB, n = 8), WB with massage (WBM, n = 8), HS for 7 days (HS7, n = 8), or HS with massage (HSM, n = 8), and (2) WB for 14 days (WB14, n = 8), HS for 14 days (HS14, n = 8), reloading (RE, n = 10), or reloading with massage (REM, n = 10) for 7 days following HS. Deuterium oxide (D2O) labeling was used to assess dynamic protein and ribosome turnover in each group and anabolic signaling pathways were assessed. Massage did have an anabolic benefit during RE or WB. In contrast, massage during HS enhanced myofibrillar protein turnover in both the massaged limb and contralateral non-massaged limb compared with HS, but this did not prevent muscle loss. Overall, the data demonstrate that massage is not an effective mechanotherapy for prevention of atrophy during muscle disuse or recovery of muscle mass during reloading in aged rats.
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Affiliation(s)
- Marcus M Lawrence
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, 73104, USA
| | - Douglas W Van Pelt
- Department of Physical Therapy, University of Kentucky, Lexington, KY, 40536, USA
- Center for Muscle Biology, University of Kentucky, Lexington, KY, 40536, USA
| | - Amy L Confides
- Department of Physical Therapy, University of Kentucky, Lexington, KY, 40536, USA
- Center for Muscle Biology, University of Kentucky, Lexington, KY, 40536, USA
| | - Zachary R Hettinger
- Department of Physical Therapy, University of Kentucky, Lexington, KY, 40536, USA
- Center for Muscle Biology, University of Kentucky, Lexington, KY, 40536, USA
| | - Emily R Hunt
- Department of Physical Therapy, University of Kentucky, Lexington, KY, 40536, USA
- Center for Muscle Biology, University of Kentucky, Lexington, KY, 40536, USA
| | - Justin J Reid
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, 73104, USA
| | - Jaime L Laurin
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, 73104, USA
| | - Frederick F Peelor
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, 73104, USA
| | - Timothy A Butterfield
- Center for Muscle Biology, University of Kentucky, Lexington, KY, 40536, USA
- Department of Athletic Training and Clinical Nutrition, University of Kentucky, Lexington, KY, 40536, USA
| | - Benjamin F Miller
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, 73104, USA
| | - Esther E Dupont-Versteegden
- Department of Physical Therapy, University of Kentucky, Lexington, KY, 40536, USA.
- Center for Muscle Biology, University of Kentucky, Lexington, KY, 40536, USA.
- College of Health Sciences, University of Kentucky, 900 S. Limestone CTW210E, Lexington, KY, 40536-0200, USA.
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64
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Lawrence MM, Zwetsloot KA, Arthur ST, Sherman CA, Huot JR, Badmaev V, Grace M, Lila MA, Nieman DC, Shanely RA. Phytoecdysteroids Do Not Have Anabolic Effects in Skeletal Muscle in Sedentary Aging Mice. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18020370. [PMID: 33418916 PMCID: PMC7825148 DOI: 10.3390/ijerph18020370] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 12/28/2020] [Accepted: 12/30/2020] [Indexed: 01/07/2023]
Abstract
Skeletal muscle mass and strength are lost with aging. Phytoecdysteroids, in particular 20-hydroxyecdysone (20E), increase protein synthesis in C2C12 skeletal muscle cells and muscle strength in young rats. The objective of this study was to determine whether an extract from Ajuga turkestanica (ATE), enriched in phytoecdysteroids, and 20E affect skeletal muscle mass and fiber size, fiber type, activation of the PI3K–Akt signaling pathway, and the mRNA levels of MAFbx, MuRF-1, and myostatin in sedentary aging mice. Aging male C57BL/6 mice (20 months old) received ATE, 20E, or vehicle (CT) once per day for 28 days or a single acute dose. Treatment did not alter body, muscle, or organ mass; fiber cross-sectional area; or fiber type in the triceps brachii or plantaris muscles. Likewise, protein synthesis signaling markers (i.e., phosphorylation of AktSer473 and p70S6kThr389) measured after either 28 days or acutely were unchanged. Neither ATE nor 20E treatment for 28 days affected the mRNA levels of MAFbx, MuRF-1, and myostatin. In conclusion, these data indicate that phytoecdysteroid treatment does not alter muscle mass or fiber type, nor does it activate protein synthesis signaling in the skeletal muscle of sedentary aging mice.
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Affiliation(s)
- Marcus M. Lawrence
- Department of Health and Exercise Science, Appalachian State University, Boone, NC 28608, USA; (M.M.L.); (K.A.Z.); (C.A.S.)
- Human Performance Laboratory, North Carolina Research Campus, Kannapolis, NC 28081, USA;
- Integrated Muscle Physiology Laboratory, Boone, NC 28607, USA
- Department of Kinesiology and Outdoor Recreation, Southern Utah University, Cedar City, UT 84720, USA
- Laboratory of Systems Physiology, Department of Kinesiology, University of North Carolina Charlotte, Charlotte, NC 28223, USA; (S.T.A.); (J.R.H.)
| | - Kevin A. Zwetsloot
- Department of Health and Exercise Science, Appalachian State University, Boone, NC 28608, USA; (M.M.L.); (K.A.Z.); (C.A.S.)
- Integrated Muscle Physiology Laboratory, Boone, NC 28607, USA
- Department of Biology, Appalachian State University, Boone, NC 20608, USA
| | - Susan T. Arthur
- Laboratory of Systems Physiology, Department of Kinesiology, University of North Carolina Charlotte, Charlotte, NC 28223, USA; (S.T.A.); (J.R.H.)
| | - Chase A. Sherman
- Department of Health and Exercise Science, Appalachian State University, Boone, NC 28608, USA; (M.M.L.); (K.A.Z.); (C.A.S.)
- Integrated Muscle Physiology Laboratory, Boone, NC 28607, USA
| | - Joshua R. Huot
- Laboratory of Systems Physiology, Department of Kinesiology, University of North Carolina Charlotte, Charlotte, NC 28223, USA; (S.T.A.); (J.R.H.)
| | | | - Mary Grace
- Plants for Human Health Institute, North Carolina Research Campus, North Carolina State University, Kannapolis, NC 28081, USA; (M.G.); (M.A.L.)
| | - Mary Ann Lila
- Plants for Human Health Institute, North Carolina Research Campus, North Carolina State University, Kannapolis, NC 28081, USA; (M.G.); (M.A.L.)
| | - David C. Nieman
- Human Performance Laboratory, North Carolina Research Campus, Kannapolis, NC 28081, USA;
- Department of Biology, Appalachian State University, Boone, NC 20608, USA
| | - R. Andrew Shanely
- Department of Health and Exercise Science, Appalachian State University, Boone, NC 28608, USA; (M.M.L.); (K.A.Z.); (C.A.S.)
- Human Performance Laboratory, North Carolina Research Campus, Kannapolis, NC 28081, USA;
- Integrated Muscle Physiology Laboratory, Boone, NC 28607, USA
- Correspondence: ; Tel.: +1-828-262-6319
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65
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Li Z, Liu C, Li S, Li T, Li Y, Wang N, Bao X, Xue P, Liu S. BMSC-Derived Exosomes Inhibit Dexamethasone-Induced Muscle Atrophy via the miR-486-5p/FoxO1 Axis. Front Endocrinol (Lausanne) 2021; 12:681267. [PMID: 34659106 PMCID: PMC8517407 DOI: 10.3389/fendo.2021.681267] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 09/14/2021] [Indexed: 01/08/2023] Open
Abstract
Sarcopenia, characterized by reduced muscle function as well as muscle mass, has been a public health problem with increasing prevalence. It might result from aging, injury, hormone imbalance and other catabolic conditions. Recently, exosomes were considered to regulate muscle regeneration and protein synthesis. In order to confirm the effect of BMSC-derived exosomes (BMSC-Exos) on muscle, dexamethasone-induced muscle atrophy was built both in vitro and in vivo. In the present research, BMSC-Exos attenuated the decrease of myotube diameter induced by dexamethasone, indicating that BMSC-Exos played a protective role in skeletal muscle atrophy. Further mechanism analysis exhibited that the content of miR-486-5p in C2C12 myotubes was up-regulated after treated with BMSC-Exos. Meanwhile, BMSC-Exos markedly downregulated the nuclear translocation of FoxO1, which plays an important role in muscle differentiation and atrophy. Importantly, the miR-486-5p inhibitor reversed the decreased expression of FoxO1 induced by BMSC-Exos. In animal experiments, BMSC-Exos inhibited dexamethasone-induced muscle atrophy, and miR-486-5p inhibitor reversed the protective effect of BMSC-Exos. These results indicating that BMSC-derived exosomes inhibit dexamethasone-induced muscle atrophy via miR486-5p/Foxo1 Axis.
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Affiliation(s)
- Ziyi Li
- Department of Endocrinology, The Third Hospital of Hebei Medical University, Shijiazhuang, China
- Key Orthopaedic Biomechanics Laboratory of Hebei Province, Orthopedic Research Institution of Hebei Province, Shijiazhuang, China
| | - Chang Liu
- Department of Endocrinology, The Third Hospital of Hebei Medical University, Shijiazhuang, China
- Key Orthopaedic Biomechanics Laboratory of Hebei Province, Orthopedic Research Institution of Hebei Province, Shijiazhuang, China
| | - Shilun Li
- Department of Joint Surgery, The Third Hospital of Hebei Medical University, Shijiazhuang, China
| | - Ting Li
- Institute of Biomedical Engineering, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China
| | - Yukun Li
- Department of Endocrinology, The Third Hospital of Hebei Medical University, Shijiazhuang, China
- Key Orthopaedic Biomechanics Laboratory of Hebei Province, Orthopedic Research Institution of Hebei Province, Shijiazhuang, China
| | - Na Wang
- Department of Endocrinology, The Third Hospital of Hebei Medical University, Shijiazhuang, China
- Key Orthopaedic Biomechanics Laboratory of Hebei Province, Orthopedic Research Institution of Hebei Province, Shijiazhuang, China
| | - Xiaoxue Bao
- Department of Endocrinology, The Third Hospital of Hebei Medical University, Shijiazhuang, China
- Key Orthopaedic Biomechanics Laboratory of Hebei Province, Orthopedic Research Institution of Hebei Province, Shijiazhuang, China
| | - Peng Xue
- Department of Endocrinology, The Third Hospital of Hebei Medical University, Shijiazhuang, China
- Key Orthopaedic Biomechanics Laboratory of Hebei Province, Orthopedic Research Institution of Hebei Province, Shijiazhuang, China
- *Correspondence: Peng Xue, ; Sijing Liu,
| | - Sijing Liu
- Editorial Department of Hebei Medical University, Hebei Medical University, Shijiazhuang, China
- *Correspondence: Peng Xue, ; Sijing Liu,
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66
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Mirzoev TM. Skeletal Muscle Recovery from Disuse Atrophy: Protein Turnover Signaling and Strategies for Accelerating Muscle Regrowth. Int J Mol Sci 2020; 21:ijms21217940. [PMID: 33114683 PMCID: PMC7663166 DOI: 10.3390/ijms21217940] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 10/08/2020] [Accepted: 10/23/2020] [Indexed: 12/15/2022] Open
Abstract
Skeletal muscle fibers have a unique capacity to adjust their metabolism and phenotype in response to alternations in mechanical loading. Indeed, chronic mechanical loading leads to an increase in skeletal muscle mass, while prolonged mechanical unloading results in a significant decrease in muscle mass (muscle atrophy). The maintenance of skeletal muscle mass is dependent on the balance between rates of muscle protein synthesis and breakdown. While molecular mechanisms regulating protein synthesis during mechanical unloading have been relatively well studied, signaling events implicated in protein turnover during skeletal muscle recovery from unloading are poorly defined. A better understanding of the molecular events that underpin muscle mass recovery following disuse-induced atrophy is of significant importance for both clinical and space medicine. This review focuses on the molecular mechanisms that may be involved in the activation of protein synthesis and subsequent restoration of muscle mass after a period of mechanical unloading. In addition, the efficiency of strategies proposed to improve muscle protein gain during recovery is also discussed.
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Affiliation(s)
- Timur M Mirzoev
- Myology Laboratory, Institute of Biomedical Problems RAS, Moscow 123007, Russia
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67
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Seo DY, Hwang BG. Effects of exercise training on the biochemical pathways associated with sarcopenia. Phys Act Nutr 2020; 24:32-38. [PMID: 33108716 PMCID: PMC7669465 DOI: 10.20463/pan.2020.0019] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 09/23/2020] [Indexed: 12/14/2022] Open
Abstract
[Purpose] Sarcopenia is considered one of the major causes of disability in the elderly population and is highly associated with aging. Exercise is an essential strategy for improving muscle health while aging and involves multiple metabolic and transcriptional adaptations. Although the beneficial effects of exercise modalities on skeletal muscle structure and function in aging are well recognized, the exact cellular and molecular mechanisms underlying the influence of exercise have not been fully elucidated. [Methods] We summarize the biochemical pathways involved in the progression and pathogenesis of sarcopenia and describe the beneficial effects of exercise training on the relevant signaling pathways associated with sarcopenia. [Results] This study briefly introduces current knowledge on the signaling pathways involved in the development of sarcopenia, effects of aerobic exercise on mitochondria-related parameters and mitochondrial function, and role of resistance exercise in the regulation of muscle protein synthesis against sarcopenia. [Conclusion] This review suggested that the beneficial effects of exercise are still under-explored, and accelerated research will help develop better modalities for the prevention, management, and treatment of sarcopenia.
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Affiliation(s)
- Dae Yun Seo
- Cardiovascular and Metabolic Disease Center, Inje University, Busan, Republic of Korea
| | - Boo Geun Hwang
- Department of Sport Rehabilitation, Tong Myong University, Busan, Republic of Korea
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68
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Ogasawara R, Knudsen JR, Li J, Ato S, Jensen TE. Rapamycin and mTORC2 inhibition synergistically reduce contraction-stimulated muscle protein synthesis. J Physiol 2020; 598:5453-5466. [PMID: 32893874 DOI: 10.1113/jp280528] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 08/24/2020] [Indexed: 12/15/2022] Open
Abstract
KEY POINTS Muscle contractions increase protein synthesis in a mechanistic target of rapamycin (mTOR)-dependent manner, yet it is unclear which/how mTOR complexes regulate muscle protein synthesis. We investigated the requirement of mTOR Complex 2 (mTORC2) in contraction-stimulated muscle protein synthesis. mTORC2 inhibition by muscle-specific Rictor knockout (Rictor mKO) did not prevent contraction-induced muscle protein synthesis. Rapamycin prevented contraction-induced muscle protein synthesis in Rictor mKO but not wild-type mice. ABSTRACT Protein synthesis increases following muscle contractions. Previous studies have shown that inhibition of the mechanistic target of rapamycin complex 1 (mTORC1) suppresses the early but not late muscle protein synthesis response, while inhibition of both mTORC1 and mTORC2 abolishes the two effects. Therefore, we hypothesized that mTORC2 regulates muscle protein synthesis following muscle contractions. To test this, we investigated the effect of mTORC2 inhibition by mouse muscle-specific Rictor knockout (Rictor mKO) on muscle protein synthesis 3 h after contraction. The right gastrocnemius muscles of Rictor mKO and wild-type (WT) mice were isometrically contracted using percutaneous electrical stimulation, while the left gastrocnemius muscles served as controls. Vehicle or the mTORC1 inhibitor rapamycin (1.5 mg/kg) was injected intraperitoneally 1 h before contraction. Treatment of WT mice with rapamycin and Rictor mKO lowered protein synthesis in general, but the response to contractions was intact 3 h after contractions in both conditions. Rapamycin treatment in Rictor mKO mice prevented contraction-stimulated muscle protein synthesis. Notably, signalling traditionally associated with mTORC1 was increased by muscle contractions despite rapamycin treatment. In rapamycin-treated Rictor mKO mice, the same mTORC1 signalling was blocked following contractions. Our results indicate that although neither rapamycin-sensitive mTOR/mTORC1 nor mTORC2 is necessary for contraction-induced muscle protein synthesis, combined inhibition of rapamycin-sensitive mTOR/mTORC1 and mTORC2 synergistically inhibits contraction-induced muscle protein synthesis.
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Affiliation(s)
- Riki Ogasawara
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan.,Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark
| | - Jonas R Knudsen
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark.,Laboratory of Microsystems 2, École Polytecgnique Fédérale de Lausanne, Switzerland
| | - Jingwen Li
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark
| | - Satoru Ato
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Thomas E Jensen
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark
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69
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Castets P, Ham DJ, Rüegg MA. The TOR Pathway at the Neuromuscular Junction: More Than a Metabolic Player? Front Mol Neurosci 2020; 13:162. [PMID: 32982690 PMCID: PMC7485269 DOI: 10.3389/fnmol.2020.00162] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 08/05/2020] [Indexed: 12/18/2022] Open
Abstract
The neuromuscular junction (NMJ) is the chemical synapse connecting motor neurons and skeletal muscle fibers. NMJs allow all voluntary movements, and ensure vital functions like breathing. Changes in the structure and function of NMJs are hallmarks of numerous pathological conditions that affect muscle function including sarcopenia, the age-related loss of muscle mass and function. However, the molecular mechanisms leading to the morphological and functional perturbations in the pre- and post-synaptic compartments of the NMJ remain poorly understood. Here, we discuss the role of the metabolic pathway associated to the kinase TOR (Target of Rapamycin) in the development, maintenance and alterations of the NMJ. This is of particular interest as the TOR pathway has been implicated in aging, but its role at the NMJ is still ill-defined. We highlight the respective functions of the two TOR-associated complexes, TORC1 and TORC2, and discuss the role of localized protein synthesis and autophagy regulation in motor neuron terminals and sub-synaptic regions of muscle fibers and their possible effects on NMJ maintenance.
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Affiliation(s)
- Perrine Castets
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
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70
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Nilsson MI, Mikhail A, Lan L, Di Carlo A, Hamilton B, Barnard K, Hettinga BP, Hatcher E, Tarnopolsky MG, Nederveen JP, Bujak AL, May L, Tarnopolsky MA. A Five-Ingredient Nutritional Supplement and Home-Based Resistance Exercise Improve Lean Mass and Strength in Free-Living Elderly. Nutrients 2020; 12:nu12082391. [PMID: 32785021 PMCID: PMC7468764 DOI: 10.3390/nu12082391] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 08/01/2020] [Accepted: 08/03/2020] [Indexed: 12/22/2022] Open
Abstract
Old age is associated with lower physical activity levels, suboptimal protein intake, and desensitization to anabolic stimuli, predisposing for age-related muscle loss (sarcopenia). Although resistance exercise (RE) and protein supplementation partially protect against sarcopenia under controlled conditions, the efficacy of home-based, unsupervised RE (HBRE) and multi-ingredient supplementation (MIS) is largely unknown. In this randomized, placebo-controlled and double-blind trial, we examined the effects of HBRE/MIS on muscle mass, strength, and function in free-living, older men. Thirty-two sedentary men underwent twelve weeks of home-based resistance band training (3 d/week), in combination with daily intake of a novel five-nutrient supplement (‘Muscle5’; M5, n = 16, 77.4 ± 2.8 y) containing whey, micellar casein, creatine, vitamin D, and omega-3 fatty acids, or an isocaloric/isonitrogenous placebo (PLA; n = 16, 74.4 ± 1.3 y), containing collagen and sunflower oil. Appendicular and total lean mass (ASM; +3%, TLM; +2%), lean mass to fat ratios (ASM/% body fat; +6%, TLM/% body fat; +5%), maximal strength (grip; +8%, leg press; +17%), and function (5-Times Sit-to-Stand time; −9%) were significantly improved in the M5 group following HBRE/MIS therapy (pre vs. post tests; p < 0.05). Fast-twitch muscle fiber cross-sectional areas of the quadriceps muscle were also significantly increased in the M5 group post intervention (Type IIa; +30.9%, Type IIx, +28.5%, p < 0.05). Sub-group analysis indicated even greater gains in total lean mass in sarcopenic individuals following HBRE/MIS therapy (TLM; +1.65 kg/+3.4%, p < 0.05). We conclude that the Muscle5 supplement is a safe, well-tolerated, and effective complement to low-intensity, home-based resistance exercise and improves lean mass, strength, and overall muscle quality in old age.
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Affiliation(s)
- Mats I. Nilsson
- Department of Pediatrics, McMaster University Medical Center, Hamilton, ON L8N 3Z5, Canada; (M.I.N.); (A.M.); (L.L.); (A.D.C.); (B.H.); (K.B.); (E.H.); (M.G.T.); (J.P.N.); (L.M.)
- Exerkine Corporation, McMaster University Medical Center, Hamilton, ON L8N 3Z5, Canada; (B.P.H.); (A.L.B.)
| | - Andrew Mikhail
- Department of Pediatrics, McMaster University Medical Center, Hamilton, ON L8N 3Z5, Canada; (M.I.N.); (A.M.); (L.L.); (A.D.C.); (B.H.); (K.B.); (E.H.); (M.G.T.); (J.P.N.); (L.M.)
- Department of Kinesiology, McMaster University, Hamilton, ON L8N 3Z5, Canada
| | - Lucy Lan
- Department of Pediatrics, McMaster University Medical Center, Hamilton, ON L8N 3Z5, Canada; (M.I.N.); (A.M.); (L.L.); (A.D.C.); (B.H.); (K.B.); (E.H.); (M.G.T.); (J.P.N.); (L.M.)
| | - Alessia Di Carlo
- Department of Pediatrics, McMaster University Medical Center, Hamilton, ON L8N 3Z5, Canada; (M.I.N.); (A.M.); (L.L.); (A.D.C.); (B.H.); (K.B.); (E.H.); (M.G.T.); (J.P.N.); (L.M.)
| | - Bethanie Hamilton
- Department of Pediatrics, McMaster University Medical Center, Hamilton, ON L8N 3Z5, Canada; (M.I.N.); (A.M.); (L.L.); (A.D.C.); (B.H.); (K.B.); (E.H.); (M.G.T.); (J.P.N.); (L.M.)
| | - Kristin Barnard
- Department of Pediatrics, McMaster University Medical Center, Hamilton, ON L8N 3Z5, Canada; (M.I.N.); (A.M.); (L.L.); (A.D.C.); (B.H.); (K.B.); (E.H.); (M.G.T.); (J.P.N.); (L.M.)
| | - Bart P. Hettinga
- Exerkine Corporation, McMaster University Medical Center, Hamilton, ON L8N 3Z5, Canada; (B.P.H.); (A.L.B.)
| | - Erin Hatcher
- Department of Pediatrics, McMaster University Medical Center, Hamilton, ON L8N 3Z5, Canada; (M.I.N.); (A.M.); (L.L.); (A.D.C.); (B.H.); (K.B.); (E.H.); (M.G.T.); (J.P.N.); (L.M.)
| | - Milla G. Tarnopolsky
- Department of Pediatrics, McMaster University Medical Center, Hamilton, ON L8N 3Z5, Canada; (M.I.N.); (A.M.); (L.L.); (A.D.C.); (B.H.); (K.B.); (E.H.); (M.G.T.); (J.P.N.); (L.M.)
| | - Joshua P. Nederveen
- Department of Pediatrics, McMaster University Medical Center, Hamilton, ON L8N 3Z5, Canada; (M.I.N.); (A.M.); (L.L.); (A.D.C.); (B.H.); (K.B.); (E.H.); (M.G.T.); (J.P.N.); (L.M.)
| | - Adam L. Bujak
- Exerkine Corporation, McMaster University Medical Center, Hamilton, ON L8N 3Z5, Canada; (B.P.H.); (A.L.B.)
| | - Linda May
- Department of Pediatrics, McMaster University Medical Center, Hamilton, ON L8N 3Z5, Canada; (M.I.N.); (A.M.); (L.L.); (A.D.C.); (B.H.); (K.B.); (E.H.); (M.G.T.); (J.P.N.); (L.M.)
| | - Mark A. Tarnopolsky
- Department of Pediatrics, McMaster University Medical Center, Hamilton, ON L8N 3Z5, Canada; (M.I.N.); (A.M.); (L.L.); (A.D.C.); (B.H.); (K.B.); (E.H.); (M.G.T.); (J.P.N.); (L.M.)
- Exerkine Corporation, McMaster University Medical Center, Hamilton, ON L8N 3Z5, Canada; (B.P.H.); (A.L.B.)
- Correspondence: ; Tel.: +905-521-2100 (ext. 76593); Fax: +905-577-8380
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Scheuren AC, D'Hulst G, Kuhn GA, Masschelein E, Wehrle E, De Bock K, Müller R. Hallmarks of frailty and osteosarcopenia in prematurely aged PolgA (D257A/D257A) mice. J Cachexia Sarcopenia Muscle 2020; 11:1121-1140. [PMID: 32596975 PMCID: PMC7432580 DOI: 10.1002/jcsm.12588] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 02/14/2020] [Accepted: 02/24/2020] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Frailty is a geriatric syndrome characterized by increased susceptibility to adverse health outcomes. One major determinant thereof is the gradual weakening of the musculoskeletal system and the associated osteosarcopenia. To improve our understanding of the underlying pathophysiology and, more importantly, to test potential interventions aimed at counteracting frailty, suitable animal models are needed. METHODS To evaluate the relevance of prematurely aged PolgA(D257A/D257A) mice as a model for frailty and osteosarcopenia, we quantified the clinical mouse frailty index in PolgA(D257A/D257A) and wild-type littermates (PolgA(+/+) , WT) with age and concertedly assessed the quantity and quality of bone and muscle tissue. Lastly, the anabolic responsiveness of skeletal muscle, muscle progenitors, and bone was assessed. RESULTS PolgA(D257A/D257A) accumulated health deficits at a higher rate compared with WT, resulting in a higher frailty index at 40 and 46 weeks of age (+166%, +278%, P < 0.0001), respectively, with no differences between genotypes at 34 weeks. Concomitantly, PolgA(D257A/D257A) displayed progressive musculoskeletal deterioration such as reduced bone and muscle mass as well as impaired functionality thereof. In addition to lower muscle weights (-14%, P < 0.05, -23%, P < 0.0001) and fibre area (-20%, P < 0.05, -22%, P < 0.0001) at 40 and 46 weeks, respectively, PolgA(D257A/D257A) showed impairments in grip strength and concentric muscle forces (P < 0.05). PolgA(D257A/D257A) mutation altered the acute response to various anabolic stimuli in skeletal muscle and muscle progenitors. While PolgA(D257A/D257A) muscles were hypersensitive to eccentric contractions as well as leucine administration, shown by larger downstream signalling response of the mechanistic target of rapamycin complex 1, myogenic progenitors cultured in vitro showed severe anabolic resistance to leucine and robust impairments in cell proliferation. Longitudinal micro-computed tomography analysis of the sixth caudal vertebrae showed that PolgA(D257A/D257A) had lower bone morphometric parameters (e.g. bone volume fraction, trabecular, and cortical thickness, P < 0.05) as well as reduced remodelling activities (e.g. bone formation and resorption rate, P < 0.05) compared with WT. When subjected to 4 weeks of cyclic loading, young but not aged PolgA(D257A/D257A) caudal vertebrae showed load-induced bone adaptation, suggesting reduced mechanosensitivity with age. CONCLUSIONS PolgA(D257A/D257A) mutation leads to hallmarks of age-related frailty and osteosarcopenia and provides a powerful model to better understand the relationship between frailty and the aging musculoskeletal system.
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Affiliation(s)
| | - Gommaar D'Hulst
- Laboratory of Exercise and HealthETH ZurichZurichSwitzerland
| | | | - Evi Masschelein
- Laboratory of Exercise and HealthETH ZurichZurichSwitzerland
| | - Esther Wehrle
- Institute for BiomechanicsETH ZurichZurichSwitzerland
| | - Katrien De Bock
- Laboratory of Exercise and HealthETH ZurichZurichSwitzerland
| | - Ralph Müller
- Institute for BiomechanicsETH ZurichZurichSwitzerland
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72
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Brunetti D, Bottani E, Segala A, Marchet S, Rossi F, Orlando F, Malavolta M, Carruba MO, Lamperti C, Provinciali M, Nisoli E, Valerio A. Targeting Multiple Mitochondrial Processes by a Metabolic Modulator Prevents Sarcopenia and Cognitive Decline in SAMP8 Mice. Front Pharmacol 2020; 11:1171. [PMID: 32848778 PMCID: PMC7411305 DOI: 10.3389/fphar.2020.01171] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 07/17/2020] [Indexed: 12/31/2022] Open
Abstract
The age-dependent declines of skeletal muscle and cognitive functions often coexist in elderly subjects. The underlying pathophysiological mechanisms share common features of mitochondrial dysfunction, which plays a central role in the development of overt sarcopenia and/or dementia. Dietary supplementation with formulations of essential and branched-chain amino acids (EAA-BCAA) is a promising preventive strategy because it can preserve mitochondrial biogenesis and function. The senescence-accelerated mouse prone 8 (SAMP8) is considered an accurate model of age-related muscular and cognitive alterations. Hence, we aimed to investigate the progression of mitochondrial dysfunctions during muscular and cognitive aging of SAMP8 mice and to study the effects of a novel EAA-BCAA-based metabolic modulator on these changes. We evaluated body condition, motor endurance, and working memory of SAMP8 mice at 5, 9, 12, and 15 months of age. Parallel changes in protein levels of mitochondrial respiratory chain subunits, regulators of mitochondrial biogenesis and dynamics, and the antioxidant response, as well as respiratory complex activities, were measured in the quadriceps femoris and the hippocampus. The same variables were assessed in 12-month-old SAMP8 mice that had received dietary supplementation with the novel EAA-BCAA formulation, containing tricarboxylic acid cycle intermediates and co-factors (PD-0E7, 1.5 mg/kg/body weight/day in drinking water) for 3 months. Contrary to untreated mice, which had a significant molecular and phenotypic impairment, PD-0E7-treated mice showed preserved healthy body condition, muscle weight to body weight ratio, motor endurance, and working memory at 12 months of age. The PD-0E7 mixture increased the protein levels and the enzymatic activities of mitochondrial complex I, II, and IV and the expression of proliferator-activated receptor γ coactivator-1α, optic atrophy protein 1, and nuclear factor, erythroid 2 like 2 in muscles and hippocampi. The mitochondrial amyloid-β-degrading pitrilysin metallopeptidase 1 was upregulated, while amyloid precursor protein was reduced in the hippocampi of PD-0E7 treated mice. In conclusion, we show that a dietary supplement tailored to boost mitochondrial respiration preserves skeletal muscle and hippocampal mitochondrial quality control and health. When administered at the early onset of age-related physical and cognitive decline, this novel metabolic inducer counteracts the deleterious effects of precocious aging in both domains.
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Affiliation(s)
- Dario Brunetti
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy.,Medical Genetics and Neurogenetics Unit, Fondazione IRCCS Istituto Neurologico C. Besta, Milan, Italy
| | - Emanuela Bottani
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy.,Department of Diagnostics and Public Health, University of Verona, Verona, Italy
| | - Agnese Segala
- Medical Genetics and Neurogenetics Unit, Fondazione IRCCS Istituto Neurologico C. Besta, Milan, Italy
| | - Silvia Marchet
- Medical Genetics and Neurogenetics Unit, Fondazione IRCCS Istituto Neurologico C. Besta, Milan, Italy
| | - Fabio Rossi
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Fiorenza Orlando
- Advanced Technology Center for Aging Research, Scientific Technological Area, IRCCS INRCA, Ancona, Italy
| | - Marco Malavolta
- Advanced Technology Center for Aging Research, Scientific Technological Area, IRCCS INRCA, Ancona, Italy
| | - Michele O Carruba
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy.,Center for Study and Research on Obesity, University of Milan, Milan, Italy
| | - Costanza Lamperti
- Medical Genetics and Neurogenetics Unit, Fondazione IRCCS Istituto Neurologico C. Besta, Milan, Italy
| | - Mauro Provinciali
- Advanced Technology Center for Aging Research, Scientific Technological Area, IRCCS INRCA, Ancona, Italy
| | - Enzo Nisoli
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy.,Center for Study and Research on Obesity, University of Milan, Milan, Italy
| | - Alessandra Valerio
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
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73
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Lynch GM, Murphy CH, Castro EDM, Roche HM. Inflammation and metabolism: the role of adiposity in sarcopenic obesity. Proc Nutr Soc 2020; 79:1-13. [PMID: 32669148 DOI: 10.1017/s0029665120007119] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Sarcopenic obesity is characterised by the double burden of diminished skeletal muscle mass and the presence of excess adiposity. From a mechanistic perspective, both obesity and sarcopenia are associated with sub-acute, chronic pro-inflammatory states that impede metabolic processes, disrupting adipose and skeletal functionality, which may potentiate disease. Recent evidence suggests that there is an important cross-talk between metabolism and inflammation, which has shifted focus upon metabolic-inflammation as a key emerging biological interaction. Dietary intake, physical activity and nutritional status are important environmental factors that may modulate metabolic-inflammation. This paradigm will be discussed within the context of sarcopenic obesity risk. There is a paucity of data in relation to the nature and the extent to which nutritional status affects metabolic-inflammation in sarcopenic obesity. Research suggests that there may be scope for the modulation of sarcopenic obesity with alterations in diet. The potential impact of increasing protein consumption and reconfiguration of dietary fat composition in human dietary interventions are evaluated. This review will explore emerging data with respect to if and how different dietary components may modulate metabolic-inflammation, particularly with respect to adiposity, within the context of sarcopenic obesity.
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Affiliation(s)
- G M Lynch
- Nutrigenomics Research Group, School of Public Health, Physiotherapy and Sports Science, UCD Institute of Food and Health, Diabetes Complications Research Centre, University College Dublin, Dublin, Ireland
| | - C H Murphy
- Nutrigenomics Research Group, School of Public Health, Physiotherapy and Sports Science, UCD Institute of Food and Health, Diabetes Complications Research Centre, University College Dublin, Dublin, Ireland
| | - E de Marco Castro
- Nutrigenomics Research Group, School of Public Health, Physiotherapy and Sports Science, UCD Institute of Food and Health, Diabetes Complications Research Centre, University College Dublin, Dublin, Ireland
| | - H M Roche
- Nutrigenomics Research Group, School of Public Health, Physiotherapy and Sports Science, UCD Institute of Food and Health, Diabetes Complications Research Centre, University College Dublin, Dublin, Ireland
- Institute for Global Food Security, Queen's University Belfast, Belfast, UK
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74
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Novel Essential Amino Acid Supplements Following Resistance Exercise Induce Aminoacidemia and Enhance Anabolic Signaling Irrespective of Age: A Proof-of-Concept Trial. Nutrients 2020; 12:nu12072067. [PMID: 32664648 PMCID: PMC7400893 DOI: 10.3390/nu12072067] [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: 06/04/2020] [Revised: 07/09/2020] [Accepted: 07/10/2020] [Indexed: 12/13/2022] Open
Abstract
We investigated the effects of ingesting a leucine-enriched essential amino acid (EAA) gel alone or combined with resistance exercise (RE) versus RE alone (control) on plasma aminoacidemia and intramyocellular anabolic signaling in healthy younger (28 ± 4 years) and older (71 ± 3 years) adults. Blood samples were obtained throughout the three trials, while muscle biopsies were collected in the postabsorptive state and 2 h following RE, following the consumption of two 50 mL EAA gels (40% leucine, 15 g total EAA), and following RE with EAA (combination (COM)). Protein content and the phosphorylation status of key anabolic signaling proteins were determined via immunoblotting. Irrespective of age, during EAA and COM peak leucinemia (younger: 454 ± 32 µM and 537 ± 111 µM; older: 417 ± 99 µM and 553 ± 136 µM) occurred ~60–120 min post-ingestion (younger: 66 ± 6 min and 120 ± 60 min; older: 90 ± 13 min and 78 ± 12 min). In the pooled sample, the area under the curve for plasma leucine and the sum of branched-chain amino acids was significantly greater in EAA and COM compared with RE. For intramyocellular signaling, significant main effects were found for condition (mTOR (Ser2481), rpS6 (Ser235/236)) and age (S6K1 (Thr421/Ser424), 4E-BP1 (Thr37/46)) in age group analyses. The phosphorylation of rpS6 was of similar magnitude (~8-fold) in pooled and age group data 2 h following COM. Our findings suggest that a gel-based, leucine-enriched EAA supplement is associated with aminoacidemia and a muscle anabolic signaling response, thus representing an effective means of stimulating muscle protein anabolism in younger and older adults following EAA and COM.
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75
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Smith HJ, Sharma A, Mair WB. Metabolic Communication and Healthy Aging: Where Should We Focus Our Energy? Dev Cell 2020; 54:196-211. [PMID: 32619405 DOI: 10.1016/j.devcel.2020.06.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 06/01/2020] [Accepted: 06/07/2020] [Indexed: 02/09/2023]
Abstract
Aging is associated with a loss of metabolic homeostasis and plasticity, which is causally linked to multiple age-onset pathologies. The majority of the interventions-genetic, dietary, and pharmacological-that have been found to slow aging and protect against age-related disease in various organisms do so by targeting central metabolic pathways. However, targeting metabolic pathways chronically and ubiquitously makes it difficult to define the downstream effects responsible for lifespan extension and often results in negative effects on growth and health, limiting therapeutic potential. Insight into how metabolic signals are relayed between tissues, cells, and organelles opens up new avenues to target metabolic regulators locally rather than globally for healthy aging. In this review, we discuss the pro-longevity effects of targeting metabolic pathways in specific tissues and how these interventions communicate with distal cells to modulate aging. These studies may be crucial in designing interventions that promote longevity without negative health consequences.
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Affiliation(s)
- Hannah J Smith
- Harvard T.H. Chan School of Public Health, Department of Molecular Metabolism, Boston, MA, USA
| | - Arpit Sharma
- Harvard T.H. Chan School of Public Health, Department of Molecular Metabolism, Boston, MA, USA
| | - William B Mair
- Harvard T.H. Chan School of Public Health, Department of Molecular Metabolism, Boston, MA, USA.
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76
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Zacharewicz E, Kalanon M, Murphy RM, Russell AP, Lamon S. MicroRNA-99b-5p downregulates protein synthesis in human primary myotubes. Am J Physiol Cell Physiol 2020; 319:C432-C440. [PMID: 32608991 DOI: 10.1152/ajpcell.00172.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
microRNAs (miRNAs) are important regulators of cellular homeostasis and exert their effect by directly controlling protein expression. We have previously reported an age-dependent negative association between microRNA-99b (miR-99b-5p) expression and muscle protein synthesis in human muscle in vivo. Here we investigated the role of miR-99b-5p as a potential negative regulator of protein synthesis via inhibition of mammalian target for rapamycin (MTOR) signaling in human primary myocytes. Overexpressing miR-99b-5p in human primary myotubes from young and old subjects significantly decreased protein synthesis with no effect of donor age. A binding interaction between miR-99b-5p and its putative binding site within the MTOR 3'-untranslated region (UTR) was confirmed in C2C12 myoblasts. The observed decline in protein synthesis was, however, not associated with a suppression of the MTOR protein but of its regulatory associated protein of mTOR complex 1 (RPTOR). These results demonstrate that modulating the expression levels of a miRNA can regulate protein synthesis in human muscle cells and provide a potential mechanism for muscle wasting in vivo.
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Affiliation(s)
- Evelyn Zacharewicz
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Ming Kalanon
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Robyn M Murphy
- Department of Physiology, Anatomy and Microbiology, School of Life Sciences, La Trobe University, Melbourne, Victoria, Australia
| | - Aaron P Russell
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Séverine Lamon
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
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77
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Markofski MM, Jennings K, Timmerman KL, Dickinson JM, Fry CS, Borack MS, Reidy PT, Deer RR, Randolph A, Rasmussen BB, Volpi E. Effect of Aerobic Exercise Training and Essential Amino Acid Supplementation for 24 Weeks on Physical Function, Body Composition, and Muscle Metabolism in Healthy, Independent Older Adults: A Randomized Clinical Trial. J Gerontol A Biol Sci Med Sci 2020; 74:1598-1604. [PMID: 29750251 DOI: 10.1093/gerona/gly109] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Essential amino acids (EAA) and aerobic exercise (AE) acutely and independently stimulate skeletal muscle protein anabolism in older adults. OBJECTIVE In this Phase 1, double-blind, placebo-controlled, randomized clinical trial, we determined if chronic EAA supplementation, AE training, or a combination of the two interventions could improve muscle mass and function by stimulating muscle protein synthesis. METHODS We phone-screened 971, enrolled 109, and randomized 50 independent, low-active, nonfrail, and nondiabetic older adults (age 72 ± 1 years). We used a 2 × 2 factorial design. The interventions were: daily nutritional supplementation (15 g EAA or placebo) and physical activity (supervised AE training 3 days/week or monitored habitual activity) for 24 weeks. Muscle strength, physical function, body composition, and muscle protein synthesis were measured before and after the 24-week intervention. RESULTS Forty-five subjects completed the 24-week intervention. VO2peak and walking speed increased (p < .05) in both AE groups, irrespective of supplementation type, but muscle strength increased only in the EAA + AE group (p < .05). EAA supplementation acutely increased (p < .05) muscle protein synthesis from basal both before and after the intervention, with a larger increase in the EAA + AE group after the intervention. Total and regional lean body mass did not change significantly with any intervention. CONCLUSIONS In nonfrail, independent, healthy older adults AE training increased walking speed and aerobic fitness, and, when combined with EAA supplementation, it also increased muscle strength and EAA-stimulated muscle protein synthesis. These increases occurred without improvements in muscle mass.
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Affiliation(s)
| | - Kristofer Jennings
- Department of Preventive Medicine and Community Health, University of Texas Medical Branch, Galveston
| | - Kyle L Timmerman
- Sealy Center on Aging, University of Texas Medical Branch, Galveston.,Division of Rehabilitation Sciences, University of Texas Medical Branch, Galveston
| | - Jared M Dickinson
- Department of Nutrition and Metabolism, University of Texas Medical Branch, Galveston
| | - Christopher S Fry
- Sealy Center on Aging, University of Texas Medical Branch, Galveston.,Division of Rehabilitation Sciences, University of Texas Medical Branch, Galveston.,Department of Nutrition and Metabolism, University of Texas Medical Branch, Galveston
| | - Michael S Borack
- Division of Rehabilitation Sciences, University of Texas Medical Branch, Galveston
| | - Paul T Reidy
- Division of Rehabilitation Sciences, University of Texas Medical Branch, Galveston
| | - Rachel R Deer
- Sealy Center on Aging, University of Texas Medical Branch, Galveston.,Division of Rehabilitation Sciences, University of Texas Medical Branch, Galveston
| | - Amanda Randolph
- Sealy Center on Aging, University of Texas Medical Branch, Galveston
| | - Blake B Rasmussen
- Sealy Center on Aging, University of Texas Medical Branch, Galveston.,Department of Nutrition and Metabolism, University of Texas Medical Branch, Galveston
| | - Elena Volpi
- Sealy Center on Aging, University of Texas Medical Branch, Galveston.,Department of Internal Medicine, University of Texas Medical Branch, Galveston
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78
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Deane CS, Ames RM, Phillips BE, Weedon MN, Willis CRG, Boereboom C, Abdulla H, Bukhari SSI, Lund JN, Williams JP, Wilkinson DJ, Smith K, Gallagher IJ, Kadi F, Szewczyk NJ, Atherton PJ, Etheridge T. The acute transcriptional response to resistance exercise: impact of age and contraction mode. Aging (Albany NY) 2020; 11:2111-2126. [PMID: 30996129 PMCID: PMC6503873 DOI: 10.18632/aging.101904] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 03/31/2019] [Indexed: 01/02/2023]
Abstract
Optimization of resistance exercise (RE) remains a hotbed of research for muscle building and maintenance. However, the interactions between the contractile components of RE (i.e. concentric (CON) and eccentric (ECC)) and age, are poorly defined. We used transcriptomics to compare age-related molecular responses to acute CON and ECC exercise. Eight young (21±1 y) and eight older (70±1 y) exercise-naïve male volunteers had vastus lateralis biopsies collected at baseline and 5 h post unilateral CON and contralateral ECC exercise. RNA was subjected to next-generation sequencing and differentially expressed (DE) genes tested for pathway enrichment using Gene Ontology (GO). The young transcriptional response to CON and ECC was highly similar and older adults displayed moderate contraction-specific profiles, with no GO enrichment. Age-specific responses to ECC revealed 104 DE genes unique to young, and 170 DE genes in older muscle, with no GO enrichment. Following CON, 15 DE genes were young muscle-specific, whereas older muscle uniquely expressed 147 up-regulated genes enriched for cell adhesion and blood vessel development, and 28 down-regulated genes involved in mitochondrial respiration, amino acid and lipid metabolism. Thus, older age is associated with contraction-specific regulation often without clear functional relevance, perhaps reflecting a degree of stochastic age-related dysregulation.
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Affiliation(s)
- Colleen S Deane
- Department of Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX1 2LU, UK
| | - Ryan M Ames
- Living Systems Institute, University of Exeter, Exeter EX4 4QD, UK
| | - Bethan E Phillips
- MRC-ARUK Centre of Research Excellence and National Institute of Health Research, Biomedical Research Centre, Postgraduate Entry Medical School, Royal Derby Hospital Centre, School of Medicine, University of Nottingham, Derby DE22 3DT, UK
| | - Michael N Weedon
- Genetics of Complex Traits, University of Exeter Medical School, University of Exeter, Exeter EX1 2LU, UK
| | - Craig R G Willis
- Department of Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX1 2LU, UK
| | - Catherine Boereboom
- MRC-ARUK Centre of Research Excellence and National Institute of Health Research, Biomedical Research Centre, Postgraduate Entry Medical School, Royal Derby Hospital Centre, School of Medicine, University of Nottingham, Derby DE22 3DT, UK
| | - Haitham Abdulla
- MRC-ARUK Centre of Research Excellence and National Institute of Health Research, Biomedical Research Centre, Postgraduate Entry Medical School, Royal Derby Hospital Centre, School of Medicine, University of Nottingham, Derby DE22 3DT, UK
| | - Syed S I Bukhari
- MRC-ARUK Centre of Research Excellence and National Institute of Health Research, Biomedical Research Centre, Postgraduate Entry Medical School, Royal Derby Hospital Centre, School of Medicine, University of Nottingham, Derby DE22 3DT, UK
| | - Jonathan N Lund
- Department of Surgery, Postgraduate Entry Medical School, Royal Derby Hospital Centre, School of Medicine, University of Nottingham, Derby DE22 3DT, UK
| | - John P Williams
- MRC-ARUK Centre of Research Excellence and National Institute of Health Research, Biomedical Research Centre, Postgraduate Entry Medical School, Royal Derby Hospital Centre, School of Medicine, University of Nottingham, Derby DE22 3DT, UK
| | - Daniel J Wilkinson
- MRC-ARUK Centre of Research Excellence and National Institute of Health Research, Biomedical Research Centre, Postgraduate Entry Medical School, Royal Derby Hospital Centre, School of Medicine, University of Nottingham, Derby DE22 3DT, UK
| | - Kenneth Smith
- MRC-ARUK Centre of Research Excellence and National Institute of Health Research, Biomedical Research Centre, Postgraduate Entry Medical School, Royal Derby Hospital Centre, School of Medicine, University of Nottingham, Derby DE22 3DT, UK
| | - Iain J Gallagher
- Faculty of Health Sciences and Sport, University of Stirling, Stirling FK9 4LA, UK
| | - Fawzi Kadi
- School of Health Sciences, Örebro University, Örebro 70182, Sweden
| | - Nathaniel J Szewczyk
- MRC-ARUK Centre of Research Excellence and National Institute of Health Research, Biomedical Research Centre, Postgraduate Entry Medical School, Royal Derby Hospital Centre, School of Medicine, University of Nottingham, Derby DE22 3DT, UK
| | - Philip J Atherton
- MRC-ARUK Centre of Research Excellence and National Institute of Health Research, Biomedical Research Centre, Postgraduate Entry Medical School, Royal Derby Hospital Centre, School of Medicine, University of Nottingham, Derby DE22 3DT, UK
| | - Timothy Etheridge
- Department of Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX1 2LU, UK
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79
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Enhanced skeletal muscle insulin sensitivity after acute resistance-type exercise is upregulated by rapamycin-sensitive mTOR complex 1 inhibition. Sci Rep 2020; 10:8509. [PMID: 32444657 PMCID: PMC7244536 DOI: 10.1038/s41598-020-65397-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 04/13/2020] [Indexed: 01/07/2023] Open
Abstract
Acute aerobic exercise (AE) increases skeletal muscle insulin sensitivity for several hours, caused by acute activation of AMP-activated protein kinase (AMPK). Acute resistance exercise (RE) also activates AMPK, possibly improving insulin-stimulated glucose uptake. However, RE-induced rapamycin-sensitive mechanistic target of rapamycin complex 1 (mTORC1) activation is higher and has a longer duration than after AE. In molecular studies, mTORC1 was shown to be upstream of insulin receptor substrate 1 (IRS-1) Ser phosphorylation residue, inducing insulin resistance. Therefore, we hypothesised that although RE increases insulin sensitivity through AMPK activation, prolonged mTORC1 activation after RE reduces RE-induced insulin sensitising effect. In this study, we used an electrical stimulation-induced RE model in rats, with rapamycin as an inhibitor of mTORC1 activation. Our results showed that RE increased insulin-stimulated glucose uptake following AMPK signal activation. However, mTORC1 activation and IRS-1 Ser632/635 and Ser612 phosphorylation were elevated 6 h after RE, with concomitant impairment of insulin-stimulated Akt signal activation. By contrast, rapamycin inhibited these prior exercise responses. Furthermore, increases in insulin-stimulated skeletal muscle glucose uptake 6 h after RE were higher in rats with rapamycin treatment than with placebo treatment. Our data suggest that mTORC1/IRS-1 signaling inhibition enhances skeletal muscle insulin-sensitising effect of RE.
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80
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Maruyama Y, Ikeda C, Wakabayashi K, Ato S, Ogasawara R. High-intensity muscle contraction-mediated increases in Akt1 and Akt2 phosphorylation do not contribute to mTORC1 activation and muscle protein synthesis. J Appl Physiol (1985) 2020; 128:830-837. [DOI: 10.1152/japplphysiol.00578.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
High-intensity muscle contraction (HiMC) is known to induce muscle protein synthesis, a process in which mechanistic target of rapamycin (mTOR) is reported to play a critical role. However, the mechanistic details have not been completely elucidated. Here, we investigated whether Akt plays a role in regulating HiMC-induced mTORC1 activation and muscle protein synthesis using a rodent model of resistance exercise and MK2206 (an Akt kinase inhibitor). The right gastrocnemius muscle of male C57BL/6J mice aged 10 wk was isometrically contracted via percutaneous electrical stimulation (100 Hz, 5 sets of 10 3-s contractions, 7-s rest between contractions, and 3-min rest between sets), while the left gastrocnemius muscle served as a control. Vehicle or MK2206 was injected intraperitoneally 6 h before contraction. MK2206 inhibited both resting and HiMC-induced phosphorylation of Akt1 Ser-473 and Akt2 Ser-474. MK2206 also inhibited the resting phosphorylation of p70S6K and 4E-BP1, which are downstream targets of mTORC1; however, it did not inhibit the HiMC-induced increase in phosphorylation of these targets. Similarly, MK2206 inhibited the resting muscle protein synthesis, but not the resistance exercise-induced muscle protein synthesis. On the basis of these observations, we conclude that although Akt2 regulates resting mTORC1 activity and muscle protein synthesis, HiMC-induced increases in mTORC1 activity and muscle protein synthesis are Akt-independent processes. NEW & NOTEWORTHY Akt is well known to be an upstream regulator of mechanistic target of rapamycin (mTOR) and has three isoforms in mammals, namely, Akt1, Akt2, and Akt3. We found that high-intensity muscle contraction (HiMC) increases Akt1 and Akt2 phosphorylation; however, HiMC-induced increases in mTORC1 activity and muscle protein synthesis are Akt-independent processes.
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Affiliation(s)
- Yuki Maruyama
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Chisaki Ikeda
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Koki Wakabayashi
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Satoru Ato
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Riki Ogasawara
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
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81
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Tan KT, Ang STJ, Tsai SY. Sarcopenia: Tilting the Balance of Protein Homeostasis. Proteomics 2019; 20:e1800411. [PMID: 31722440 DOI: 10.1002/pmic.201800411] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 11/04/2019] [Indexed: 12/14/2022]
Abstract
Sarcopenia, defined as age-associated decline of muscle mass and function, is a risk factor for mortality and disability, and comorbid with several chronic diseases such as type II diabetes and cardiovascular diseases. Clinical trials showed that nutritional supplements had positive effects on muscle mass, but not on muscle function and strength, demonstrating our limited understanding of the molecular events involved in the ageing muscle. Protein homeostasis, the equilibrium between protein synthesis and degradation, is proposed as the major mechanism underlying the development of sarcopenia. As the key central regulator of protein homeostasis, the mammalian target of rapamycin (mTOR) is proposed to be essential for muscle hypertrophy. Paradoxically, sustained activation of mTOR complex 1 (mTORC1) is associated with a loss of sensitivity to extracellular signaling in the elderly. It is not understood why sustained mTORC1 activity, which should induce muscle hypertrophy, instead results in muscle atrophy. Here, recent findings on the implications of disrupting protein homeostasis on muscle physiology and sarcopenia development in the context of mTOR/protein kinase B (AKT) signaling are reviewed. Understanding the role of these molecular mechanisms during the ageing process will contribute towards the development of targeted therapies that will improve protein metabolism and reduce sarcopenia.
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Affiliation(s)
- Kuan Ting Tan
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 2 Medical Drive, MD9 Admin Office, Singapore, 117597, Singapore
| | - Seok-Ting Jamie Ang
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 2 Medical Drive, MD9 Admin Office, Singapore, 117597, Singapore
| | - Shih-Yin Tsai
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 2 Medical Drive, MD9 Admin Office, Singapore, 117597, Singapore
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82
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Van Pelt DW, Confides AL, Abshire SM, Hunt ER, Dupont-Versteegden EE, Butterfield TA. Age-related responses to a bout of mechanotherapy in skeletal muscle of rats. J Appl Physiol (1985) 2019; 127:1782-1791. [PMID: 31670600 PMCID: PMC6962605 DOI: 10.1152/japplphysiol.00641.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 10/14/2019] [Accepted: 10/24/2019] [Indexed: 12/25/2022] Open
Abstract
Cyclic compressive loading (CCL) is a massage mimetic that improves muscle regrowth from atrophy in adult rats. Therefore, we tested if a single bout of CCL increases anabolic signaling and protein synthesis in muscle during normal, weight-bearing conditions in gastrocnemius muscle from adult and aged rats. Male Brown Norway/F344 rats at 10 (adult) and 30 (aged) months of age were assigned control or CCL (receiving a single bout of CCL). Twenty-four hours following a single bout of CCL there was no change in protein synthesis, Akt, or GSK3β signaling at either age, despite adult rats having higher abundance and activation of mechanosensitive pathways (integrins and integrin-linked kinase). Murf1 was elevated in response to CCL in both age groups, potentially indicating muscle remodeling. Muscle from aged rats exhibited an increase in heat shock protein (HSP) 25 and HSP70 and in the cold shock protein RNA-binding motif 3 (RBM3), demonstrating a unique stress response to CCL in aged muscle only. Finally, muscle from aged rats exhibited higher basal protein synthesis that was corroborated by elevated eIF2Bε and rpS6 signaling, without an additional effect of CCL. In summary, a single bout of CCL does not have anabolic effects on skeletal muscle during normal, weight-bearing conditions, even though it has previously been shown to improve regrowth from atrophy. These data demonstrate that interventions that may help recover from atrophy do not necessarily induce muscle hypertrophy in unperturbed conditions.NEW & NOTEWORTHY Massage has been demonstrated to be an effective mechanotherapy to improve recovery from atrophy in adult skeletal muscle; however, this study shows that a single bout of massage fails to increase protein synthesis or anabolic signaling in adult or aged skeletal muscle during normal, weight-bearing conditions. Altogether, our data suggest massage is a useful mechanotherapy for preserving skeletal muscle when combined with other interventions but is not an anabolic stimulus on its own.
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Affiliation(s)
- Douglas W Van Pelt
- Department of Physical Therapy, University of Kentucky, Lexington, Kentucky
- Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
| | - Amy L Confides
- Department of Physical Therapy, University of Kentucky, Lexington, Kentucky
- Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
| | - Sarah M Abshire
- Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
- Department of Athletic Training and Clinical Nutrition, University of Kentucky, Lexington, Kentucky
| | - Emily R Hunt
- Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
- Rehabilitation Sciences PhD Program, University of Kentucky, Lexington, Kentucky
| | - Esther E Dupont-Versteegden
- Department of Physical Therapy, University of Kentucky, Lexington, Kentucky
- Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
| | - Timothy A Butterfield
- Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
- Department of Athletic Training and Clinical Nutrition, University of Kentucky, Lexington, Kentucky
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83
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Nutritional and Pharmacological Interventions to Expedite Recovery Following Muscle-Damaging Exercise in Older Adults: A Narrative Review of the Literature. J Aging Phys Act 2019; 27:914-928. [PMID: 30859892 DOI: 10.1123/japa.2018-0351] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Exercise-induced muscle damage (EIMD) manifests as muscle soreness, inflammation, and reductions in force generating capacity that can last for several days after exercise. The ability to recover and repair damaged tissues following EIMD is impaired with age, with older adults (≥50 years old) experiencing a slower rate of recovery than their younger counterparts do for the equivalent exercise bout. This narrative review discusses the literature examining the effect of nutritional or pharmacological supplements taken to counter the potentially debilitating effects of EIMD in older adults. Studies have assessed the effects of nonsteroidal anti-inflammatory drugs, vitamin C and/or E, or higher protein diets on recovery in older adults. Each intervention showed some promise for attenuating EIMD, but, overall, there is a paucity of available data in this population, and more studies are required to determine the influence of nutrition or pharmacological interventions on EIMD in older adults.
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84
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Aversa Z, Zhang X, Fielding RA, Lanza I, LeBrasseur NK. The clinical impact and biological mechanisms of skeletal muscle aging. Bone 2019; 127:26-36. [PMID: 31128290 PMCID: PMC6708726 DOI: 10.1016/j.bone.2019.05.021] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 05/15/2019] [Accepted: 05/15/2019] [Indexed: 12/25/2022]
Abstract
Skeletal muscle is a highly plastic tissue that remarkably adapts to diverse stimuli including exercise, injury, disuse, and, as discussed here, aging. Humans achieve peak skeletal muscle mass and strength in mid-life and then experience a progressive decline of up to 50% by the ninth decade. The loss of muscle mass and function with aging is a phenomenon termed sarcopenia. It is evidenced by the loss and atrophy of muscle fibers and the concomitant accretion of fat and fibrous tissue. Sarcopenia has been recognized as a key driver of limitations in physical function and mobility, but is perhaps less appreciated for its role in age-related metabolic dysfunction and loss of organismal resilience. Similar to other tissues, muscle is prone to multiple forms of age-related molecular and cellular damage, including disrupted protein turnover, impaired regenerative capacity, cellular senescence, and mitochondrial dysfunction. The objective of this review is to highlight the clinical consequences of skeletal muscle aging, and provide insights into potential biological mechanisms. In light of population aging, strategies to improve muscle health in older adults promise to have a profound public health impact.
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Affiliation(s)
- Zaira Aversa
- Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, MN, United States of America; Robert and Arlene Kogod Center on Aging, Mayo Clinic, Rochester, MN, United States of America
| | - Xu Zhang
- Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, MN, United States of America; Robert and Arlene Kogod Center on Aging, Mayo Clinic, Rochester, MN, United States of America
| | - Roger A Fielding
- Nutrition, Exercise Physiology, and Sarcopenia Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, United States of America
| | - Ian Lanza
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic, Rochester, MN, United States of America
| | - Nathan K LeBrasseur
- Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, MN, United States of America; Robert and Arlene Kogod Center on Aging, Mayo Clinic, Rochester, MN, United States of America.
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85
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Barclay RD, Burd NA, Tyler C, Tillin NA, Mackenzie RW. The Role of the IGF-1 Signaling Cascade in Muscle Protein Synthesis and Anabolic Resistance in Aging Skeletal Muscle. Front Nutr 2019; 6:146. [PMID: 31552262 PMCID: PMC6746962 DOI: 10.3389/fnut.2019.00146] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 08/23/2019] [Indexed: 12/14/2022] Open
Abstract
Sarcopenia is defined as the combined loss of skeletal muscle strength, function, and/or mass with aging. This degenerative loss of muscle mass is associated with poor quality of life and early mortality humans. The loss of muscle mass occurs due to acute changes in daily muscle net protein balance (NPB). It is generally believed a poor NPB occurs due to reduced muscle protein synthetic responses to exercise, dietary amino acid availability, or an insensitivity of insulin to suppress breakdown. Hence, aging muscles appear to be resistant to the anabolic action of exercise and protein (amino acids or hormonal) when compared to their younger counterparts. The mechanisms that underpin anabolic resistance to anabolic stimuli (protein and resistance exercise) are multifactorial and may be partly driven by poor lifestyle choices (increased sedentary time and reduced dietary protein intake) as well as an inherent dysregulated mechanism in old muscles irrespective of the environmental stimuli. The insulin like growth factor 1 (IGF-1), Akt /Protein Kinase B and mechanistic target of rapamycin (mTOR) pathway is the primary driver between mechanical contraction and protein synthesis and may be a site of dysregulation between old and younger people. Therefore, our review aims to describe and summarize the differences seen in older muscle in this pathway in response to resistance exercise (RE) and describe approaches that researchers have sought out to maximize the response in muscle. Furthermore, this review will present the hypothesis that inositol hexakisphosphate kinase 1 (IP6K1) may be implicated in IGF-1 signaling and thus sarcopenia, based on recent evidence that IGF-1 and insulin share some intracellular bound signaling events and that IP6K1 has been implicated in skeletal muscle insulin resistance.
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Affiliation(s)
- Richie D Barclay
- Department of Life Sciences, University of Roehampton, London, United Kingdom
| | - Nicholas A Burd
- Division of Nutritional Sciences, Department of Kinesiology and Community Health, University of Illinois, Urbana, IL, United States
| | - Christopher Tyler
- Department of Life Sciences, University of Roehampton, London, United Kingdom
| | - Neale A Tillin
- Department of Life Sciences, University of Roehampton, London, United Kingdom
| | - Richard W Mackenzie
- Department of Life Sciences, University of Roehampton, London, United Kingdom
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86
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Hodson N, West DWD, Philp A, Burd NA, Moore DR. Molecular regulation of human skeletal muscle protein synthesis in response to exercise and nutrients: a compass for overcoming age-related anabolic resistance. Am J Physiol Cell Physiol 2019; 317:C1061-C1078. [PMID: 31461340 DOI: 10.1152/ajpcell.00209.2019] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Skeletal muscle mass, a strong predictor of longevity and health in humans, is determined by the balance of two cellular processes, muscle protein synthesis (MPS) and muscle protein breakdown. MPS seems to be particularly sensitive to changes in mechanical load and/or nutritional status; therefore, much research has focused on understanding the molecular mechanisms that underpin this cellular process. Furthermore, older individuals display an attenuated MPS response to anabolic stimuli, termed anabolic resistance, which has a negative impact on muscle mass and function, as well as quality of life. Therefore, an understanding of which, if any, molecular mechanisms contribute to anabolic resistance of MPS is of vital importance in formulation of therapeutic interventions for such populations. This review summarizes the current knowledge of the mechanisms that underpin MPS, which are broadly divided into mechanistic target of rapamycin complex 1 (mTORC1)-dependent, mTORC1-independent, and ribosomal biogenesis-related, and describes the evidence that shows how they are regulated by anabolic stimuli (exercise and/or nutrition) in healthy human skeletal muscle. This review also summarizes evidence regarding which of these mechanisms may be implicated in age-related skeletal muscle anabolic resistance and provides recommendations for future avenues of research that can expand our knowledge of this area.
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Affiliation(s)
- Nathan Hodson
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada
| | - Daniel W D West
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada
| | - Andrew Philp
- Garvan Institute of Medical Research, Darlinghurst, Sydney, New South Wales, Australia
| | - Nicholas A Burd
- Department of Kinesiology and Community Health, University of Illinois, Urbana, Illinois
| | - Daniel R Moore
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada
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87
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Kirby TJ. Mechanosensitive pathways controlling translation regulatory processes in skeletal muscle and implications for adaptation. J Appl Physiol (1985) 2019; 127:608-618. [PMID: 31295035 DOI: 10.1152/japplphysiol.01031.2018] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The ability of myofibers to sense and respond appropriately to mechanical signals is one of the primary determinants of the skeletal muscle phenotype. In response to a change in mechanical load, muscle cells alter their protein metabolism, primarily through the regulation of protein synthesis rate. Protein synthesis rates are determined by both translation efficiency and translational capacity within the muscle. Translational capacity is strongly determined by the ribosome content of the muscle; thus the regulation of ribosomal biogenesis by mechanical inputs has been an area of recent interest. Despite the clear association between mechanical signals and changes in protein metabolism, the molecular pathways that link these events are still not fully elucidated. This review focuses on recent studies looking at how mechanosignaling impacts translational events. The role of impaired mechanotransduction in aging is discussed, as is the connection between age-dependent signaling defects and compromised ribosomal biogenesis during mechanical overload. Finally, emerging evidence suggests that the nucleus can act as a mechanosensitive element and that this mode of mechanotransduction may have an important role in skeletal muscle physiology and adaptation.
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Affiliation(s)
- Tyler J Kirby
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York.,Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York
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88
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Sato S, Nomura M, Yamana I, Uchiyama A, Furuichi Y, Manabe Y, Fujii NL. A new in vitro muscle contraction model and its application for analysis of mTORC1 signaling in combination with contraction and beta-hydroxy-beta-methylbutyrate administration. Biosci Biotechnol Biochem 2019; 83:1851-1857. [PMID: 31159662 DOI: 10.1080/09168451.2019.1625261] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Several food constituents augment exercise-induced muscle strength improvement; however, the detailed mechanism underlying these combined effects is unknown because of the lack of a cultured cell model for evaluating the contraction-induced muscle protein synthesis level. Here, we aimed to establish a new in vitro muscle contraction model for analyzing the activation of mammalian target of rapamycin complex 1 (mTORC1) signaling. We adopted the tetanic electric stimulation of 50 V at 100 Hz for 10 min in L6.C11 myotubes. Akt, ERK1/2, and p70S6K phosphorylation increased significantly after electrical pulse stimulation (EPS), compared to untreated cells. Next, we used this model to analyze mTORC1 signaling in combination with exercise and beta-hydroxy-beta-methylbutyrate (HMB), an l-leucine metabolite. p70S6K phosphorylation increased significantly in the EPS+HMB group compared to that in the EPS-alone group. These findings show that our model could be used to analyze mTORC1 signaling and that HMB enhances muscle contraction-activated mTORC1 signaling.
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Affiliation(s)
- Satoko Sato
- Research and Development Headquarters, Lion Corporation , Odawara , Japan
| | - Mitsuru Nomura
- Research and Development Headquarters, Lion Corporation , Odawara , Japan
| | - Ikko Yamana
- Research and Development Headquarters, Lion Corporation , Odawara , Japan
| | - Akira Uchiyama
- Research and Development Headquarters, Lion Corporation , Odawara , Japan
| | - Yasuro Furuichi
- Department of Health Promotion Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University , Hachioji , Japan
| | - Yasuko Manabe
- Department of Health Promotion Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University , Hachioji , Japan
| | - Nobuharu L Fujii
- Department of Health Promotion Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University , Hachioji , Japan
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89
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Nabuco HC, Tomeleri CM, Junior PS, Fernandes RR, Cavalcante EF, Nunes JP, Cunha PF, Dos Santos L, Cyrino ES. Effects of higher habitual protein intake on resistance-training-induced changes in body composition and muscular strength in untrained older women: A clinical trial study. Nutr Health 2019; 25:103-112. [PMID: 30909813 DOI: 10.1177/0260106019838365] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
BACKGROUND Aging is accompanied by progressive and accentuated decline in muscular strength and skeletal muscle mass, affecting health and functional autonomy. Both resistance training (RT) and diet are strategies that may contribute to improvement in the health of the elderly. AIM The purpose of this study was to evaluate the effects of higher habitual protein intake on RT-induced changes in body composition and strength in untrained postmenopausal women. METHODS Seventy older women were submitted to an RT program. Body composition, muscular strength, and dietary intake (24 h dietary recall) were performed pre- and post-intervention. To verify different intervention effects according to protein intake of the participants, the sample was separated into tertiles according to protein intake: low, moderate, and high protein intake. RESULTS A time vs. group interaction ( p < 0.05) was observed, with high protein intake presenting greater increases compared with low protein intake, for skeletal muscle mass (5.3% vs. 1.3%), lower limb lean soft tissue (4.9% vs. 1.4%), upper lean soft tissue (4.9% vs. 1.2%), preacher curl (24% vs. 15.2%), and total strength (16.4% vs. 11.7%). A time vs. group interaction ( p < 0.05) was observed, with high protein intake presenting greater increases compared with moderate protein intake, for skeletal muscle mass (5.3% vs. 3.2%). In all groups, a main effect of time ( p < 0.05) was observed for knee extension and chest press. CONCLUSIONS We conclude that intake of >1.0 g/kg/day of protein promotes gains in skeletal muscle mass and muscular strength after RT in untrained older women.
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Affiliation(s)
- Hellen Cg Nabuco
- 1 Federal Institute of Science and Technology of Mato Grosso, Cuiabá, Mato Grosso, Brazil
- 2 Physical Education and Sport Center, Londrina State University, Londrina, PR, Brazil
| | - Crisieli M Tomeleri
- 2 Physical Education and Sport Center, Londrina State University, Londrina, PR, Brazil
- 3 Faculty of Physical Education, University of Campinas - Unicamp, Brazil
| | - Paulo Sugihara Junior
- 2 Physical Education and Sport Center, Londrina State University, Londrina, PR, Brazil
| | - Rodrigo R Fernandes
- 2 Physical Education and Sport Center, Londrina State University, Londrina, PR, Brazil
| | - Edilaine F Cavalcante
- 2 Physical Education and Sport Center, Londrina State University, Londrina, PR, Brazil
| | - João Pedro Nunes
- 2 Physical Education and Sport Center, Londrina State University, Londrina, PR, Brazil
| | - Paolo F Cunha
- 2 Physical Education and Sport Center, Londrina State University, Londrina, PR, Brazil
| | - Leandro Dos Santos
- 2 Physical Education and Sport Center, Londrina State University, Londrina, PR, Brazil
| | - Edilson S Cyrino
- 2 Physical Education and Sport Center, Londrina State University, Londrina, PR, Brazil
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90
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Jacob KJ, Chevalier S, Lamarche M, Morais JA. Leucine Supplementation Does Not Alter Insulin Sensitivity in Prefrail and Frail Older Women following a Resistance Training Protocol. J Nutr 2019; 149:959-967. [PMID: 31149709 DOI: 10.1093/jn/nxz038] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 11/12/2018] [Accepted: 02/20/2019] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Frailty is a clinical condition associated with loss of muscle mass and strength (sarcopenia). Although sarcopenia has multifactorial causes, it might be partly attributed to a blunted response to anabolic stimuli. Leucine acutely increases muscle protein synthesis, and resistance training (RT) is the strongest stimuli to counteract sarcopenia and was recently shown to improve insulin sensitivity (IS) in frail older women. Discrepancies exist regarding whether chronic supplementation of leucine in conjunction with RT can improve muscle mass and IS. OBJECTIVE The aim of this double-blinded placebo-controlled study was to determine the effects of leucine supplementation and RT on IS in prefrail and frail older women. METHODS Using the Fried criteria, 19 nondiabetic prefrail (1-2 criteria) and frail (≥3 criteria) older women (77.5 ± 1.3 y; body mass index (kg/m2): 25.1 ± 0.9) underwent a 3-mo intervention of RT 3 times/wk with protein-optimized diet of 1.2 g·kg-1·d-1 and 7.5 g·d-1 of l-leucine supplementation compared with placebo l-alanine. Pre-/postintervention primary outcomes were fasting plasma glucose, serum insulin, and 4-h responses to a standard meal of complete liquid formula. Secondary outcomes of resting energy expenditure using indirect calorimetry and body composition using dual-energy X-ray absorptiometry were obtained. Paired t tests analyzed pooled data, and 2-factor repeated-measures ANOVA determined supplementation, training, and interaction effects. RESULTS No significant time, group, or interaction effects were observed for postprandial areas under the curve of serum insulin or plasma glucose or for resting energy expenditure in l-leucine compared with l-alanine. Total lean body mass increased and percentage body fat decreased significantly for both groups postintervention (0.76 ± 0.13 and -0.92 ± 0.33 kg, respectively; time effect: P < 0.01). CONCLUSIONS IS was not affected by RT and leucine supplementation in nondiabetic prefrail and frail older women. Therefore, leucine supplementation does not appear to influence IS under these conditions. This trial was registered at clinicaltrials.gov as NCT01922167.
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Affiliation(s)
- Kathryn J Jacob
- Research Institute of the McGill University Health Centre, Montreal, Canada
| | - Stéphanie Chevalier
- Research Institute of the McGill University Health Centre, Montreal, Canada.,Division of Geriatric Medicine, McGill University, MUHC-Montreal General Hospital, Montreal, Canada.,School of Human Nutrition, McGill University, Sainte-Anne-de-Bellevue, Canada
| | - Marie Lamarche
- Research Institute of the McGill University Health Centre, Montreal, Canada
| | - José A Morais
- Research Institute of the McGill University Health Centre, Montreal, Canada.,Division of Geriatric Medicine, McGill University, MUHC-Montreal General Hospital, Montreal, Canada.,School of Human Nutrition, McGill University, Sainte-Anne-de-Bellevue, Canada
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91
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Sgrò P, Sansone M, Sansone A, Sabatini S, Borrione P, Romanelli F, Di Luigi L. Physical exercise, nutrition and hormones: three pillars to fight sarcopenia. Aging Male 2019; 22:75-88. [PMID: 29451419 DOI: 10.1080/13685538.2018.1439004] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Sarcopenia is a pathophysiological condition diffused in elderly people; it represents a social issue due to the longer life expectancy and the growing aging population. It affects negatively quality of life and it represents a risk factor for other pathologies, such as diabetes, cardiovascular disease, and obesity. No silver bullet exists to hinder sarcopenia, but it may be counteracted by physical exercise, nutrition, and a proper endocrine milieu. Indeed, we aim to analyze the scientific literature to give to clinician effective advices to counteract sarcopenia. Main text: Physical exercise, proper nutrition, optimized hormonal homeostasis represent the three pillars to fight sarcopenia. Physical exercise represents the most effective remedy to face sarcopenia, in particular if it is combined with a proper diet and with an adequate endocrine milieu. Consistency in training, adequate daily protein intake and eugonadism seems to be the keys to fight sarcopenia. The combination of these three pillars might act synergistically. CONCLUSIONS Optimization of these factors may increase their efficiency; however, scientific data may be sometimes confusing so far. Therefore, we aim to give practical advices to clinician to identify and to highlight the most important aspects in each of these three factors that should be addressed.
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Affiliation(s)
- Paolo Sgrò
- a Department of Movement, Human and Health Sciences, Unit of Endocrinology , Università degli Studi di Roma "Foro Italico" , Rome , Italy
| | - Massimiliano Sansone
- b Department of Experimental Medicine, Section of Medical Pathophysiology, Food Science and Endocrinology , Sapienza - Università di Roma , Rome , Italy
| | - Andrea Sansone
- b Department of Experimental Medicine, Section of Medical Pathophysiology, Food Science and Endocrinology , Sapienza - Università di Roma , Rome , Italy
| | - Stefania Sabatini
- c Department of Movement, Human and Health Sciences, Unit of Biology, Genetics and Biochemistry , Università degli Studi di Roma "Foro Italico" , Rome , Italy
| | - Paolo Borrione
- d Department of Movement, Human and Health Sciences, Unit of Internal Medicine , Università degli Studi di Roma "Foro Italico" , Rome , Italy
| | - Francesco Romanelli
- b Department of Experimental Medicine, Section of Medical Pathophysiology, Food Science and Endocrinology , Sapienza - Università di Roma , Rome , Italy
| | - Luigi Di Luigi
- a Department of Movement, Human and Health Sciences, Unit of Endocrinology , Università degli Studi di Roma "Foro Italico" , Rome , Italy
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92
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Li Q, Luo Z. Transcriptional Regulatory Network Analysis to Reveal the Key Genes Involved in Skeletal Muscle Injury. J Comput Biol 2019; 26:1090-1099. [PMID: 31120305 DOI: 10.1089/cmb.2019.0025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Skeletal muscle is among the three major muscle types, and skeletal muscle injury (SMI) can elevate the risk of dependency and falls. This study is designed to explore the key genes involved in SMI and skeletal muscle regeneration. Microarray data set GSE81096, which included 11 injured skeletal muscle stem cell samples and 12 noninjured skeletal muscle stem cell samples, was from Gene Expression Omnibus. The differentially expressed genes (DEGs) between injured and noninjured samples were screened by R package limma, and then were performed with enrichment analysis based on the Database for Annotation, Visualization, and Integrated Discovery. Followed by protein-protein interaction (PPI), transcriptional regulatory analyses were conducted using Cytoscape software. A total of 1018 DEGs were screened from the injured samples, among which four upregulated genes and nine downregulated genes were predicted as transcription factors. Besides, four modules were identified from the PPI network. In the transcriptional regulatory network, E2F1, E2F4, JUNB, FOS, and MEF2C had higher degrees. Moreover, E2F4 and FOS might function in SMI separately through targeting E2F1 and JUNB. E2F1, E2F4, JUNB, FOS, and MEF2C might be involved in SMI and skeletal muscle regeneration.
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Affiliation(s)
- Qi Li
- 32nd Ward, Emergency Surgery, Fujian Provincial Hospital, Fuzhou, China
| | - Zhengqiang Luo
- Department of Orthopedics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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93
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Abstract
The loss of skeletal muscle, called sarcopenia, is an inevitable event during the aging process, and significantly impacts quality of life. Autophagy is known to reduce muscle atrophy caused by dysfunctional organelles, even though the molecular mechanism remains unclear. Here, we have discuss the current understanding of exercise-induced autophagy activation in skeletal muscle regeneration and remodeling, leading to sarcopenia intervention. With aging, dysregulation of autophagy flux inhibits lysosomal storage processes involved in muscle biogenesis. AMPK-ULK1 and the FoxO/PGC-1α signaling pathways play a critical role in the induction of autophagy machinery in skeletal muscle, thus these pathways could be targets for therapeutics development. Autophagy has been also shown to be a critical regulator of stem cell fate, which determines satellite cell differentiation into muscle fiber, thereby increasing muscle mass. This review aims to provide a comprehensive understanding of the physiological role of autophagy in skeletal muscle aging and sarcopenia.
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Affiliation(s)
- Sung Sup Park
- Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141; Department of Life Science, University of Science and Technology (UST), Daejeon 34113, Korea
| | - Young-Kyo Seo
- Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Korea
| | - Ki-Sun Kwon
- Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141; Department of Life Science, University of Science and Technology (UST), Daejeon 34113, Korea
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94
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Jęśko H, Stępień A, Lukiw WJ, Strosznajder RP. The Cross-Talk Between Sphingolipids and Insulin-Like Growth Factor Signaling: Significance for Aging and Neurodegeneration. Mol Neurobiol 2019; 56:3501-3521. [PMID: 30140974 PMCID: PMC6476865 DOI: 10.1007/s12035-018-1286-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 07/25/2018] [Indexed: 12/20/2022]
Abstract
Bioactive sphingolipids: sphingosine, sphingosine-1-phosphate (S1P), ceramide, and ceramide-1-phosphate (C1P) are increasingly implicated in cell survival, proliferation, differentiation, and in multiple aspects of stress response in the nervous system. The opposite roles of closely related sphingolipid species in cell survival/death signaling is reflected in the concept of tightly controlled sphingolipid rheostat. Aging has a complex influence on sphingolipid metabolism, disturbing signaling pathways and the properties of lipid membranes. A metabolic signature of stress resistance-associated sphingolipids correlates with longevity in humans. Moreover, accumulating evidence suggests extensive links between sphingolipid signaling and the insulin-like growth factor I (IGF-I)-Akt-mTOR pathway (IIS), which is involved in the modulation of aging process and longevity. IIS integrates a wide array of metabolic signals, cross-talks with p53, nuclear factor κB (NF-κB), or reactive oxygen species (ROS) and influences gene expression to shape the cellular metabolic profile and stress resistance. The multiple connections between sphingolipids and IIS signaling suggest possible engagement of these compounds in the aging process itself, which creates a vulnerable background for the majority of neurodegenerative disorders.
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Affiliation(s)
- Henryk Jęśko
- Department of Cellular Signalling, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Pawińskiego, 5, 02-106, Poland
| | - Adam Stępień
- Central Clinical Hospital of the Ministry of National Defense, Department of Neurology, Military Institute of Medicine, Warsaw, Szaserów, 128, 04-141, Poland
| | - Walter J Lukiw
- LSU Neuroscience Center and Departments of Neurology and Ophthalmology, Louisiana State University School of Medicine, New Orleans, USA
| | - Robert P Strosznajder
- Laboratory of Preclinical Research and Environmental Agents, Department of Neurosurgery, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Pawińskiego, 5, 02-106, Poland.
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95
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Nunes PR, Barcelos LC, Oliveira AA, Furlanetto R, Martins FM, Resende EA, Orsatti FL. Muscular Strength Adaptations and Hormonal Responses After Two Different Multiple-Set Protocols of Resistance Training in Postmenopausal Women. J Strength Cond Res 2019; 33:1276-1285. [DOI: 10.1519/jsc.0000000000001788] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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96
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Graber TG, Fandrey KR, Thompson LV. Novel individualized power training protocol preserves physical function in adult and older mice. GeroScience 2019; 41:165-183. [PMID: 31076998 PMCID: PMC6544743 DOI: 10.1007/s11357-019-00069-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 04/16/2019] [Indexed: 11/27/2022] Open
Abstract
Sarcopenia, the age-related loss of muscle mass and strength, contributes to frailty, functional decline, and reduced quality of life in older adults. Exercise is a recognized therapy for sarcopenia and muscle dysfunction, though not a cure. Muscle power declines at an increased rate compared to force, and force output declines earlier than mass. Thus, there is a need for research of exercise focusing on improving power output and functionality in older adults. Our primary purpose was proof-of-concept that a novel individualized power exercise modality would induce positive adaptations in adult mice, before the exercise program was applied to an aged cohort. We hypothesized that after following our protocol, both adult and older mice would show improved function, though there would be evidence of anabolic resistance in the older mice. Male C57BL/6 mice (12 months of age at study conclusion) were randomized into control (n = 9) and exercise (n = 6) groups. The trained group used progressive resistance (with a weighted harness) and intensity (~ 4-10 rpm) on a custom motorized running wheel. The mice trained similarly to a human workout regimen (4-5 sets/session, 3 sessions/week, for 12 weeks). We determined significant (p < 0.05) positive adaptations post-intervention, including: neuromuscular function (rotarod), strength/endurance (inverted cling grip test), training physiology (force/power output per session), muscle size (soleus mass), and power/velocity of contraction (in vitro physiology). Secondly, we trained a cohort of older male mice (28 months old at conclusion): control (n = 12) and exercised (n = 8). While the older exercised mice did preserve function and gain benefits, they also demonstrated evidence of anabolic resistance.
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Affiliation(s)
- Ted G. Graber
- Department of Nutrition and Metabolism, Division of Rehabilitation Science, University of Texas Medical Branch, Galveston, TX USA
| | - Katie R. Fandrey
- Program in Physical Therapy, University of Minnesota-Twin Cities, Minneapolis, MN USA
| | - LaDora V. Thompson
- Department of Physical Therapy & Athletic Training, Boston University, Boston, MA USA
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97
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Brightwell CR, Markofski MM, Moro T, Fry CS, Porter C, Volpi E, Rasmussen BB. Moderate-intensity aerobic exercise improves skeletal muscle quality in older adults. TRANSLATIONAL SPORTS MEDICINE 2019; 2:109-119. [PMID: 31123725 PMCID: PMC6518946 DOI: 10.1002/tsm2.70] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 01/16/2019] [Accepted: 01/22/2019] [Indexed: 12/12/2022]
Abstract
Sarcopenia, age-associated involuntary loss of muscle and strength, can progress to clinically relevant functional decline. Resistance exercise attenuates muscle and strength loss but may not be feasible for some older adults. Aerobic exercise training (AET) improves cardiopulmonary health; however, effects on protein turnover, muscle mass, and strength are less clear. We aimed to determine whether AET improves basal myofibrillar protein synthesis (MPS) and capillarization, promoting hypertrophy and strength. We hypothesized that AET improves strength with increased MPS and capillarization. Older adults were randomized to non-exercise (NON; n = 11, 71.4 ± 4.18 years) or exercise (EX; n = 12, 73.7 ± 4.05 years). EX completed 24 weeks of AET (walking 3×/week, 45 minutes, 70% heart rate reserve); NON remained sedentary. A stable isotope tracer was infused. MPS and capillarization were analyzed from vastus lateralis muscle biopsies. Strength was measured via isokinetic dynamometry. Lean mass was determined with dual-energy X-ray absorptiometry. Basal MPS increased in EX (+50.7%, P = 0.01) along with capillary density (+66.4%, P = 0.03), peak oxygen consumption (+15.8%, P = 0.01), quadriceps strength (+15.1%, P = 0.01), and muscle quality (peak torque divided by leg lean mass, +15.5%, P = 0.01). Lean mass did not change (P > 0.05). AET increases muscle protein turnover and capillarization in older adults, improving muscle quality.
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Affiliation(s)
- Camille R. Brightwell
- Department of Nutrition and MetabolismUniversity of Texas Medical BranchGalvestonTexas
- Division of Neuroscience, Cell Biology and AnatomyUniversity of Texas Medical BranchGalvestonTexas
| | | | - Tatiana Moro
- Department of Nutrition and MetabolismUniversity of Texas Medical BranchGalvestonTexas
- Sealy Center on AgingUniversity of Texas Medical BranchGalvestonTexas
- Center for RecoveryPhysical Activity, and NutritionUniversity of Texas Medical BranchGalvestonTexas
| | - Christopher S. Fry
- Department of Nutrition and MetabolismUniversity of Texas Medical BranchGalvestonTexas
- Center for RecoveryPhysical Activity, and NutritionUniversity of Texas Medical BranchGalvestonTexas
| | - Craig Porter
- Center for RecoveryPhysical Activity, and NutritionUniversity of Texas Medical BranchGalvestonTexas
- Metabolism UnitShriners Hospitals for ChildrenGalvestonTexas
| | - Elena Volpi
- Sealy Center on AgingUniversity of Texas Medical BranchGalvestonTexas
- Center for RecoveryPhysical Activity, and NutritionUniversity of Texas Medical BranchGalvestonTexas
| | - Blake B. Rasmussen
- Department of Nutrition and MetabolismUniversity of Texas Medical BranchGalvestonTexas
- Sealy Center on AgingUniversity of Texas Medical BranchGalvestonTexas
- Center for RecoveryPhysical Activity, and NutritionUniversity of Texas Medical BranchGalvestonTexas
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98
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Horstman AMH, Kouw IWK, van Dijk JW, Hamer HM, Groen BBL, van Kranenburg J, Gorissen SHM, van Loon LJC. The Muscle Protein Synthetic Response to Whey Protein Ingestion Is Greater in Middle-Aged Women Compared With Men. J Clin Endocrinol Metab 2019; 104:994-1004. [PMID: 30423113 DOI: 10.1210/jc.2018-01734] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 11/07/2018] [Indexed: 02/05/2023]
Abstract
RATIONALE Muscle mass maintenance is largely regulated by the postprandial rise in muscle protein synthesis rates. It remains unclear whether postprandial protein handling differs between women and men. METHODS Healthy men (43 ± 3 years; body mass index, 23.4 ± 0.4 kg/m2; n = 12) and women (46 ± 2 years; body mass index, 21.3 ± 0.5 kg/m2; n = 12) received primed continuous infusions of l-[ring-2H5]-phenylalanine and l-[ring-3,5-2H2]-tyrosine and ingested 25 g intrinsically l-[1-13C]-phenylalanine-labeled whey protein. Blood samples and muscle biopsies were collected to assess dietary protein digestion and amino acid absorption kinetics as well as basal and postprandial myofibrillar protein synthesis rates. RESULTS Plasma phenylalanine and leucine concentrations rapidly increased after protein ingestion (both P < 0.001), with no differences between middle-aged women and men (Time × Sex, P = 0.307 and 0.529, respectively). The fraction of dietary protein-derived phenylalanine that appeared in the circulation over the 5-hour postprandial period averaged 56 ± 1% and 53 ± 1% in women and men, respectively (P = 0.145). Myofibrillar protein synthesis rates increased (Time, P = 0.010) from 0.035 ± 0.004%/h and 0.030 ± 0.002%/h in the postabsorptive state (t test, P = 0.319) to 0.045 ± 0.002%/h and 0.034 ± 0.002%/h in the 5-hour postprandial phase in middle-aged women and men, respectively, with higher postprandial myofibrillar protein synthesis rates in women compared with men (t test, P = 0.005). Middle-aged women showed a greater increase in myofibrillar protein synthesis rates during the early (0 to 2 hours) postprandial period compared with men (Time × Sex, P = 0.001). CONCLUSIONS There are no differences in postabsorptive myofibrillar protein synthesis rates between middle-aged women and men. The myofibrillar protein synthetic response to the ingestion of 25 g whey protein is greater in women than in men.
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Affiliation(s)
- Astrid M H Horstman
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, Netherlands
- TIFN Top Institute Food and Nutrition, Wageningen, Netherlands
| | - Imre W K Kouw
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, Netherlands
- TIFN Top Institute Food and Nutrition, Wageningen, Netherlands
| | - Jan-Willem van Dijk
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, Netherlands
- TIFN Top Institute Food and Nutrition, Wageningen, Netherlands
| | - Henrike M Hamer
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, Netherlands
- TIFN Top Institute Food and Nutrition, Wageningen, Netherlands
| | - Bart B L Groen
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, Netherlands
- TIFN Top Institute Food and Nutrition, Wageningen, Netherlands
| | - Janneau van Kranenburg
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, Netherlands
- TIFN Top Institute Food and Nutrition, Wageningen, Netherlands
| | - Stefan H M Gorissen
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, Netherlands
- TIFN Top Institute Food and Nutrition, Wageningen, Netherlands
| | - Luc J C van Loon
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, Netherlands
- TIFN Top Institute Food and Nutrition, Wageningen, Netherlands
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99
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Lavin KM, Roberts BM, Fry CS, Moro T, Rasmussen BB, Bamman MM. The Importance of Resistance Exercise Training to Combat Neuromuscular Aging. Physiology (Bethesda) 2019; 34:112-122. [PMID: 30724133 PMCID: PMC6586834 DOI: 10.1152/physiol.00044.2018] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 11/05/2018] [Accepted: 11/05/2018] [Indexed: 12/15/2022] Open
Abstract
Older adults undergoing age-related decrements in muscle health can benefit substantially from resistance exercise training, a potent stimulus for whole muscle and myofiber hypertrophy, neuromuscular performance gains, and improved functional mobility. With the use of advancing technologies, research continues to elucidate the mechanisms of and heterogeneity in adaptations to resistance exercise training beyond differences in exercise prescription. This review highlights the current knowledge in these areas and emphasizes knowledge gaps that require future attention of the field.
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Affiliation(s)
- Kaleen M Lavin
- UAB Center for Exercise Medicine, University of Alabama at Birmingham , Birmingham, Alabama
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham , Birmingham, Alabama
| | - Brandon M Roberts
- UAB Center for Exercise Medicine, University of Alabama at Birmingham , Birmingham, Alabama
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham , Birmingham, Alabama
| | - Christopher S Fry
- Department of Nutrition and Metabolism, University of Texas Medical Branch , Galveston, Texas ; and
- Sealy Center on Aging, University of Texas Medical Branch , Galveston, Texas
| | - Tatiana Moro
- Department of Nutrition and Metabolism, University of Texas Medical Branch , Galveston, Texas ; and
- Sealy Center on Aging, University of Texas Medical Branch , Galveston, Texas
| | - Blake B Rasmussen
- Department of Nutrition and Metabolism, University of Texas Medical Branch , Galveston, Texas ; and
- Sealy Center on Aging, University of Texas Medical Branch , Galveston, Texas
| | - Marcas M Bamman
- UAB Center for Exercise Medicine, University of Alabama at Birmingham , Birmingham, Alabama
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham , Birmingham, Alabama
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100
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West DWD, Marcotte GR, Chason CM, Juo N, Baehr LM, Bodine SC, Baar K. Normal Ribosomal Biogenesis but Shortened Protein Synthetic Response to Acute Eccentric Resistance Exercise in Old Skeletal Muscle. Front Physiol 2019; 9:1915. [PMID: 30692935 PMCID: PMC6339931 DOI: 10.3389/fphys.2018.01915] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 12/18/2018] [Indexed: 01/06/2023] Open
Abstract
Anabolic resistance to feeding in aged muscle is well-characterized; however, whether old skeletal muscle is intrinsically resistant to acute mechanical loading is less clear. The aim of this study was to determine the impact of aging on muscle protein synthesis (MPS), ribosome biogenesis, and protein breakdown in skeletal muscle following a single bout of resistance exercise. Adult male F344/BN rats aged 10 (Adult) and 30 (Old) months underwent unilateral maximal eccentric contractions of the hindlimb. Precursor rRNA increased early post-exercise (6-18 h), preceding elevations in ribosomal mass at 48 h in Adult and Old; there were no age-related differences in these responses. MPS increased early post-exercise in both Adult and Old; however, at 48 h of recovery, MPS returned to baseline in Old but not Adult. This abbreviated protein synthesis response in Old was associated with decreased levels of IRS1 protein and increased BiP, CHOP and eIF2α levels. Other than these responses, anabolic signaling was similar in Adult and Old muscle in the acute recovery phase. Basal proteasome activity was lower in Old, and resistance exercise did not increase the activity of either the ATP-dependent or independent proteasome, or autophagy (Cathepsin L activity) in either Adult or Old muscle. We conclude that MPS and ribosome biogenesis in response to maximal resistance exercise in old skeletal muscle are initially intact; however, the MPS response is abbreviated in Old, which may be the result of ER stress and/or blunted exercise-induced potentiation of the MPS response to feeding.
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Affiliation(s)
- Daniel W D West
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
| | - George R Marcotte
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, CA, United States
| | - Courtney M Chason
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, CA, United States
| | - Natalie Juo
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, CA, United States
| | - Leslie M Baehr
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
| | - Sue C Bodine
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States.,Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, CA, United States.,VA Northern California Health Care System, Mather, CA, United States
| | - Keith Baar
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States.,Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, CA, United States.,VA Northern California Health Care System, Mather, CA, United States
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