1
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Fuertes-Alvarez S, Izeta A. Terminal Schwann Cell Aging: Implications for Age-Associated Neuromuscular Dysfunction. Aging Dis 2021; 12:494-514. [PMID: 33815879 PMCID: PMC7990373 DOI: 10.14336/ad.2020.0708] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 07/08/2020] [Indexed: 12/11/2022] Open
Abstract
Action potential is transmitted to muscle fibers through specialized synaptic interfaces called neuromuscular junctions (NMJs). These structures are capped by terminal Schwann cells (tSCs), which play essential roles during formation and maintenance of the NMJ. tSCs are implicated in the correct communication between nerves and muscles, and in reinnervation upon injury. During aging, loss of muscle mass and strength (sarcopenia and dynapenia) are due, at least in part, to the progressive loss of contacts between muscle fibers and nerves. Despite the important role of tSCs in NMJ function, very little is known on their implication in the NMJ-aging process and in age-associated denervation. This review summarizes the current knowledge about the implication of tSCs in the age-associated degeneration of NMJs. We also speculate on the possible mechanisms underlying the observed phenotypes.
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Affiliation(s)
- Sandra Fuertes-Alvarez
- 1Biodonostia, Tissue Engineering Group, Paseo Dr. Begiristain, s/n, San Sebastian 20014, Spain
| | - Ander Izeta
- 1Biodonostia, Tissue Engineering Group, Paseo Dr. Begiristain, s/n, San Sebastian 20014, Spain.,2Tecnun-University of Navarra, School of Engineering, Department of Biomedical Engineering and Science, Paseo Mikeletegi, 48, San Sebastian 20009, Spain
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2
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Anton SD, Cruz-Almeida Y, Singh A, Alpert J, Bensadon B, Cabrera M, Clark DJ, Ebner NC, Esser KA, Fillingim RB, Goicolea SM, Han SM, Kallas H, Johnson A, Leeuwenburgh C, Liu AC, Manini TM, Marsiske M, Moore F, Qiu P, Mankowski RT, Mardini M, McLaren C, Ranka S, Rashidi P, Saini S, Sibille KT, Someya S, Wohlgemuth S, Tucker C, Xiao R, Pahor M. Innovations in Geroscience to enhance mobility in older adults. Exp Gerontol 2020; 142:111123. [PMID: 33191210 PMCID: PMC7581361 DOI: 10.1016/j.exger.2020.111123] [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] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 10/15/2020] [Accepted: 10/16/2020] [Indexed: 02/07/2023]
Abstract
Aging is the primary risk factor for functional decline; thus, understanding and preventing disability among older adults has emerged as an important public health challenge of the 21st century. The science of gerontology - or geroscience - has the practical purpose of "adding life to the years." The overall goal of geroscience is to increase healthspan, which refers to extending the portion of the lifespan in which the individual experiences enjoyment, satisfaction, and wellness. An important facet of this goal is preserving mobility, defined as the ability to move independently. Despite this clear purpose, this has proven to be a challenging endeavor as mobility and function in later life are influenced by a complex interaction of factors across multiple domains. Moreover, findings over the past decade have highlighted the complexity of walking and how targeting multiple systems, including the brain and sensory organs, as well as the environment in which a person lives, can have a dramatic effect on an older person's mobility and function. For these reasons, behavioral interventions that incorporate complex walking tasks and other activities of daily living appear to be especially helpful for improving mobility function. Other pharmaceutical interventions, such as oxytocin, and complementary and alternative interventions, such as massage therapy, may enhance physical function both through direct effects on biological mechanisms related to mobility, as well as indirectly through modulation of cognitive and socioemotional processes. Thus, the purpose of the present review is to describe evolving interventional approaches to enhance mobility and maintain healthspan in the growing population of older adults in the United States and countries throughout the world. Such interventions are likely to be greatly assisted by technological advances and the widespread adoption of virtual communications during and after the COVID-19 era.
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Affiliation(s)
- Stephen D Anton
- University of Florida, Department of Aging and Geriatric Research, 2004 Mowry Road, Gainesville, FL 32611, United States.
| | - Yenisel Cruz-Almeida
- University of Florida, Department of Community Dentistry and Behavioral Science, 1329 SW Archer Road, Gainesville, FL 32610, United States.
| | - Arashdeep Singh
- University of Florida, Department of Pharmacodynamics, College of Pharmacy, 1345 Center Drive, Gainesville, FL 32610, United States.
| | - Jordan Alpert
- University of Florida, College of Journalism and Communications, Gainesville, FL 32610, United States.
| | - Benjamin Bensadon
- University of Florida, Department of Aging and Geriatric Research, 2004 Mowry Road, Gainesville, FL 32611, United States.
| | - Melanie Cabrera
- University of Florida, Department of Aging and Geriatric Research, 2004 Mowry Road, Gainesville, FL 32611, United States.
| | - David J Clark
- University of Florida, Department of Aging and Geriatric Research, 2004 Mowry Road, Gainesville, FL 32611, United States.
| | - Natalie C Ebner
- University of Florida, Department of Psychology, 945 Center Drive, Gainesville, FL 32611, United States.
| | - Karyn A Esser
- University of Florida, Department of Physiology and Functional Genomics, 1345 Center Drive, Gainesville, FL, United States.
| | - Roger B Fillingim
- University of Florida, Department of Community Dentistry and Behavioral Science, 1329 SW Archer Road, Gainesville, FL 32610, United States.
| | - Soamy Montesino Goicolea
- University of Florida, Department of Community Dentistry and Behavioral Science, 1329 SW Archer Road, Gainesville, FL 32610, United States.
| | - Sung Min Han
- University of Florida, Department of Aging and Geriatric Research, 2004 Mowry Road, Gainesville, FL 32611, United States.
| | - Henrique Kallas
- University of Florida, Department of Aging and Geriatric Research, 2004 Mowry Road, Gainesville, FL 32611, United States.
| | - Alisa Johnson
- University of Florida, Department of Aging and Geriatric Research, 2004 Mowry Road, Gainesville, FL 32611, United States.
| | - Christiaan Leeuwenburgh
- University of Florida, Department of Aging and Geriatric Research, 2004 Mowry Road, Gainesville, FL 32611, United States.
| | - Andrew C Liu
- University of Florida, Department of Physiology and Functional Genomics, 1345 Center Drive, Gainesville, FL, United States.
| | - Todd M Manini
- University of Florida, Department of Aging and Geriatric Research, 2004 Mowry Road, Gainesville, FL 32611, United States.
| | - Michael Marsiske
- University of Florida, Department of Clinical & Health Psychology, 1225 Center Drive, Gainesville, FL 32610, United States.
| | - Frederick Moore
- University of Florida, Department of Surgery, Gainesville, FL 32610, United States.
| | - Peihua Qiu
- University of Florida, Department of Biostatistics, Gainesville, FL 32611, United States.
| | - Robert T Mankowski
- University of Florida, Department of Aging and Geriatric Research, 2004 Mowry Road, Gainesville, FL 32611, United States.
| | - Mamoun Mardini
- University of Florida, Department of Aging and Geriatric Research, 2004 Mowry Road, Gainesville, FL 32611, United States.
| | - Christian McLaren
- University of Florida, Department of Aging and Geriatric Research, 2004 Mowry Road, Gainesville, FL 32611, United States.
| | - Sanjay Ranka
- University of Florida, Department of Computer & Information Science & Engineering, Gainesville, FL 32611, United States.
| | - Parisa Rashidi
- University of Florida, Department of Biomedical Engineering. P.O. Box 116131. Gainesville, FL 32610, United States.
| | - Sunil Saini
- University of Florida, Department of Aging and Geriatric Research, 2004 Mowry Road, Gainesville, FL 32611, United States.
| | - Kimberly T Sibille
- University of Florida, Department of Aging and Geriatric Research, 2004 Mowry Road, Gainesville, FL 32611, United States.
| | - Shinichi Someya
- University of Florida, Department of Aging and Geriatric Research, 2004 Mowry Road, Gainesville, FL 32611, United States.
| | - Stephanie Wohlgemuth
- University of Florida, Department of Aging and Geriatric Research, 2004 Mowry Road, Gainesville, FL 32611, United States.
| | - Carolyn Tucker
- University of Florida, Department of Psychology, 945 Center Drive, Gainesville, FL 32611, United States.
| | - Rui Xiao
- University of Florida, Department of Aging and Geriatric Research, 2004 Mowry Road, Gainesville, FL 32611, United States.
| | - Marco Pahor
- University of Florida, Department of Aging and Geriatric Research, 2004 Mowry Road, Gainesville, FL 32611, United States.
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3
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Badawi Y, Nishimune H. Impairment Mechanisms and Intervention Approaches for Aged Human Neuromuscular Junctions. Front Mol Neurosci 2020; 13:568426. [PMID: 33328881 PMCID: PMC7717980 DOI: 10.3389/fnmol.2020.568426] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 10/16/2020] [Indexed: 12/19/2022] Open
Abstract
The neuromuscular junction (NMJ) is a chemical synapse formed between a presynaptic motor neuron and a postsynaptic muscle cell. NMJs in most vertebrate species share many essential features; however, some differences distinguish human NMJs from others. This review will describe the pre- and postsynaptic structures of human NMJs and compare them to NMJs of laboratory animals. We will focus on age-dependent declines in function and changes in the structure of human NMJs. Furthermore, we will describe insights into the aging process revealed from mouse models of accelerated aging. In addition, we will compare aging phenotypes to other human pathologies that cause impairments of pre- and postsynaptic structures at NMJs. Finally, we will discuss potential intervention approaches for attenuating age-related NMJ dysfunction and sarcopenia in humans.
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Affiliation(s)
- Yomna Badawi
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, KS, United States
| | - Hiroshi Nishimune
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, KS, United States.,Neurobiology of Aging, Tokyo Metropolitan Institute of Gerontology, Itabashi, Japan
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Comment on: "Mitochondrial Mechanisms of Neuromuscular Junction Degeneration with Aging. Cells 2020, 9, 197". Cells 2020; 9:cells9081796. [PMID: 32751058 PMCID: PMC7464736 DOI: 10.3390/cells9081796] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 07/28/2020] [Indexed: 12/28/2022] Open
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5
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Anagnostou ME, Hepple RT. Mitochondrial Mechanisms of Neuromuscular Junction Degeneration with Aging. Cells 2020; 9:cells9010197. [PMID: 31941062 PMCID: PMC7016881 DOI: 10.3390/cells9010197] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 01/07/2020] [Accepted: 01/08/2020] [Indexed: 12/11/2022] Open
Abstract
Skeletal muscle deteriorates with aging, contributing to physical frailty, poor health outcomes, and increased risk of mortality. Denervation is a major driver of changes in aging muscle. This occurs through transient denervation-reinnervation events throughout the aging process that remodel the spatial domain of motor units and alter fiber type. In advanced age, reinnervation wanes, leading to persistent denervation that accelerates muscle atrophy and impaired muscle contractility. Alterations in the muscle fibers and motoneurons are both likely involved in driving denervation through destabilization of the neuromuscular junction. In this respect, mitochondria are implicated in aging and age-related neurodegenerative disorders, and are also likely key to aging muscle changes through their direct effects in muscle fibers and through secondary effects mediated by mitochondrial impairments in motoneurons. Indeed, the large abundance of mitochondria in muscle fibers and motoneurons, that are further concentrated on both sides of the neuromuscular junction, likely renders the neuromuscular junction especially vulnerable to age-related mitochondrial dysfunction. Manifestations of mitochondrial dysfunction with aging include impaired respiratory function, elevated reactive oxygen species production, and increased susceptibility to permeability transition, contributing to reduced ATP generating capacity, oxidative damage, and apoptotic signaling, respectively. Using this framework, in this review we summarize our current knowledge, and relevant gaps, concerning the potential impact of mitochondrial impairment on the aging neuromuscular junction, and the mechanisms involved.
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Sonjak V, Jacob KJ, Spendiff S, Vuda M, Perez A, Miguez K, Minozzo FC, Spake C, Morais JA, Hepple RT. Reduced Mitochondrial Content, Elevated Reactive Oxygen Species, and Modulation by Denervation in Skeletal Muscle of Prefrail or Frail Elderly Women. J Gerontol A Biol Sci Med Sci 2019; 74:1887-1895. [DOI: 10.1093/gerona/glz066] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Indexed: 12/12/2022] Open
Abstract
Abstract
Denervation and mitochondrial impairment are implicated in age-related skeletal muscle atrophy and may play a role in physical frailty. We recently showed that denervation modulates muscle mitochondrial function in octogenarian men, but this has not been examined in elderly women. On this basis, we tested the hypothesis that denervation plays a modulating role in mitochondrial impairment in skeletal muscle from prefrail or frail elderly (FE) women. Mitochondrial respiratory capacity and reactive oxygen species emission were examined in permeabilized myofibers obtained from vastus lateralis muscle biopsies from FE and young inactive women. Muscle respiratory capacity was reduced in proportion to a reduction in a mitochondrial marker protein in FE, and mitochondrial reactive oxygen species emission was elevated in FE versus young inactive group. Consistent with a significant accumulation of neural cell adhesion molecule-positive muscle fibers in FE (indicative of denervation), a 50% reduction in reactive oxygen species production after pharmacologically inhibiting the denervation-mediated reactive oxygen species response in FE women suggests a significant modulation of mitochondrial function by denervation. In conclusion, our data support the hypothesis that denervation plays a modulating role in skeletal muscle mitochondrial function in FE women, suggesting therapeutic strategies in advanced age should focus on the causes and treatment of denervation.
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Affiliation(s)
- Vita Sonjak
- Department of Kinesiology and Physical Education, McGill University, Montréal, Québec
- Research Institute of the McGill University Health Centre, McGill University, Montréal, Québec
| | - Kathryn J Jacob
- Research Institute of the McGill University Health Centre, McGill University, Montréal, Québec
| | - Sally Spendiff
- Children’s Hospital of Eastern Ontario Research Institute, University of Ottawa, Canada
| | - Madhusudanarao Vuda
- Department of Cardiovascular Medicine, Medical School, University of Minnesota, Minneapolis
| | - Anna Perez
- Research Institute of the McGill University Health Centre, McGill University, Montréal, Québec
| | - Kayla Miguez
- McGill University, Grande Prairie Regional College, Canada
| | - Fabio C Minozzo
- Department of Kinesiology and Physical Education, Grande Prairie Regional College, Canada
| | - Carole Spake
- Medical School, Brown University, Providence, Rhode Island
| | - José A Morais
- Research Institute of the McGill University Health Centre, McGill University, Montréal, Québec
- Division of Geriatric Medicine, Department of Medicine, McGill University, Montréal, Québec, Canada
| | - Russell T Hepple
- Department of Medicine, McGill University, Montréal, Québec, Canada
- Department of Physical Therapy, College of Public Health and Health Professionals, University of Florida, Gainesville
- Department of Physiology and Functional Genomics, College of Medicine, University of Florida, Gainesville
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7
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Affiliation(s)
- Russell T. Hepple
- Department of Physical TherapyDepartment of Physiology & Functional Genomics, Institute of Aging, and Myology InstituteUniversity of FloridaGainesvilleFLUSA
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8
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St-Jean-Pelletier F, Pion CH, Leduc-Gaudet JP, Sgarioto N, Zovilé I, Barbat-Artigas S, Reynaud O, Alkaterji F, Lemieux FC, Grenon A, Gaudreau P, Hepple RT, Chevalier S, Belanger M, Morais JA, Aubertin-Leheudre M, Gouspillou G. The impact of ageing, physical activity, and pre-frailty on skeletal muscle phenotype, mitochondrial content, and intramyocellular lipids in men. J Cachexia Sarcopenia Muscle 2017; 8:213-228. [PMID: 27897402 PMCID: PMC5377417 DOI: 10.1002/jcsm.12139] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 06/20/2016] [Accepted: 07/12/2016] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND The exact impact of ageing on skeletal muscle phenotype and mitochondrial and lipid content remains controversial, probably because physical activity, which greatly influences muscle physiology, is rarely accounted for. The present study was therefore designed to investigate the effects of ageing, physical activity, and pre-frailty on skeletal muscle phenotype, and mitochondrial and intramyocellular lipid content in men. METHODS Recreationally active young adult (20-30 yo; YA); active (ACT) and sedentary (SED) middle-age (50-65 yo; MA-ACT and MA-SED); and older (65 + yo; 65 + ACT and 65 + SED) and pre-frail older (65 + PF) men were recruited. Muscle biopsies from the vastus lateralis were collected to assess, on muscle cross sections, muscle phenotype (using myosin heavy chain isoforms immunolabelling), the fibre type-specific content of mitochondria (by quantifying the succinate dehydrogenase stain intensity), and the fibre type-specific lipid content (by quantifying the Oil Red O stain intensity). RESULTS Only 65 + SED and 65 + PF displayed significantly lower overall and type IIa fibre sizes vs. YA. 65 + SED displayed a lower type IIa fibre proportion vs. YA. MA-SED and 65 + SED displayed a higher hybrid type IIa/IIx fibre proportion vs. YA. Sedentary and pre-frail, but not active, men displayed lower mitochondrial content irrespective of fibre type vs. YA. 65 + SED, but not 65 + ACT, displayed a higher lipid content in type I fibres vs. YA. Finally, mitochondrial content, but not lipid content, was positively correlated with indices of muscle function, functional capacity, and insulin sensitivity across all subjects. CONCLUSIONS Taken altogether, our results indicate that ageing in sedentary men is associated with (i) complex changes in muscle phenotype preferentially affecting type IIa fibres; (ii) a decline in mitochondrial content affecting all fibre types; and (iii) an increase in lipid content in type I fibres. They also indicate that physical activity partially protects from the effects of ageing on muscle phenotype, mitochondrial content, and lipid accumulation. No skeletal specific muscle phenotype of pre-frailty was observed.
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Affiliation(s)
- Félix St-Jean-Pelletier
- Département de Sciences de l'activité Physique, Faculté des Sciences, UQAM, Quebec, Canada.,Groupe de Recherche en Activité Physique Adaptée, Québec, Canada
| | - Charlotte H Pion
- Groupe de Recherche en Activité Physique Adaptée, Québec, Canada.,Département de Biologie, Faculté des Sciences, UQAM, Quebec, Canada
| | - Jean-Philippe Leduc-Gaudet
- Département de Sciences de l'activité Physique, Faculté des Sciences, UQAM, Quebec, Canada.,Groupe de Recherche en Activité Physique Adaptée, Québec, Canada
| | - Nicolas Sgarioto
- Département de Sciences de l'activité Physique, Faculté des Sciences, UQAM, Quebec, Canada
| | - Igor Zovilé
- Département de Sciences de l'activité Physique, Faculté des Sciences, UQAM, Quebec, Canada
| | - Sébastien Barbat-Artigas
- Groupe de Recherche en Activité Physique Adaptée, Québec, Canada.,Département de Biologie, Faculté des Sciences, UQAM, Quebec, Canada.,Département de Neurosciences, Faculté de Médecine, Université de Montréal, Québec, Canada
| | - Olivier Reynaud
- Département de Sciences de l'activité Physique, Faculté des Sciences, UQAM, Quebec, Canada
| | - Feras Alkaterji
- Département de Sciences de l'activité Physique, Faculté des Sciences, UQAM, Quebec, Canada
| | - François C Lemieux
- Département de Sciences de l'activité Physique, Faculté des Sciences, UQAM, Quebec, Canada.,Groupe de Recherche en Activité Physique Adaptée, Québec, Canada
| | - Alexis Grenon
- Département de Sciences de l'activité Physique, Faculté des Sciences, UQAM, Quebec, Canada
| | - Pierrette Gaudreau
- Département de Médecine, UdeM, et Centre de Recherche du Centre Hospitalier de l'UdeM, Quebec, Canada
| | - Russell T Hepple
- Department of Kinesiology and Division of Critical Care Medicine, McGill University, Quebec, Canada.,McGill University Health Centre-Research Institute, Quebec, Canada
| | - Stéphanie Chevalier
- McGill University Health Centre-Research Institute, Quebec, Canada.,Division of Geriatric Medicine, McGill University, Quebec, Canada
| | - Marc Belanger
- Département de Sciences de l'activité Physique, Faculté des Sciences, UQAM, Quebec, Canada.,Groupe de Recherche en Activité Physique Adaptée, Québec, Canada
| | - José A Morais
- McGill University Health Centre-Research Institute, Quebec, Canada.,Division of Geriatric Medicine, McGill University, Quebec, Canada
| | - Mylène Aubertin-Leheudre
- Département de Sciences de l'activité Physique, Faculté des Sciences, UQAM, Quebec, Canada.,Groupe de Recherche en Activité Physique Adaptée, Québec, Canada.,Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Quebec, Canada
| | - Gilles Gouspillou
- Département de Sciences de l'activité Physique, Faculté des Sciences, UQAM, Quebec, Canada.,Groupe de Recherche en Activité Physique Adaptée, Québec, Canada.,Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Quebec, Canada
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Spendiff S, Vuda M, Gouspillou G, Aare S, Perez A, Morais JA, Jagoe RT, Filion ME, Glicksman R, Kapchinsky S, MacMillan NJ, Pion CH, Aubertin-Leheudre M, Hettwer S, Correa JA, Taivassalo T, Hepple RT. Denervation drives mitochondrial dysfunction in skeletal muscle of octogenarians. J Physiol 2016; 594:7361-7379. [PMID: 27619626 DOI: 10.1113/jp272487] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 08/31/2016] [Indexed: 01/26/2023] Open
Abstract
KEY POINTS Mitochondria are frequently implicated in the ageing of skeletal muscle, although the role of denervation in modulating mitochondrial function in ageing muscle is unknown. We show that increased sensitivity to apoptosis initiation occurs prior to evidence of persistent denervation and is thus a primary mitochondrial defect in ageing muscle worthy of therapeutic targeting. However, at more advanced age, mitochondrial function changes are markedly impacted by persistent sporadic myofibre denervation, suggesting the mitochondrion may be a less viable therapeutic target. ABSTRACT Experimental denervation modulates mitochondrial function, where changes in both reactive oxygen species (ROS) and sensitivity to permeability transition are implicated in the resultant muscle atrophy. Notably, although denervation occurs sporadically in ageing muscle, its impact on ageing muscle mitochondria is unknown. Because this information has important therapeutic implications concerning targeting the mitochondrion in ageing muscle, we examined mitochondrial function in skeletal muscle from four groups of humans, comprising two active (mean ± SD age: 23.7 ± 2.7 years and 71.2 ± 4.9 years) and two inactive groups (64.8 ± 3.1 years and 82.5 ± 4.8 years), and compared this with a murine model of sporadic denervation. We tested the hypothesis that, although some alterations of mitochondrial function in aged muscle are attributable to a primary organelle defect, mitochondrial dysfunction would be impacted by persistent denervation in advanced age. Both ageing in humans and sporadic denervation in mice increased mitochondrial sensitivity to permeability transition (humans, P = 0.004; mice, P = 0.01). To determine the contribution of sporadic denervation to mitochondrial function, we pharmacologically inhibited the denervation-induced ROS response. This reduced ROS emission by 60% (P = 0.02) in sporadically denervated mouse muscle, which is similar to that seen in humans older than 75 years (-66%, P = 0.02) but not those younger than 75 years. We conclude that an increased sensitivity to permeability transition is a primary mitochondrial defect in ageing muscle. However, at more advanced age, when muscle atrophy becomes more clinically severe, mitochondrial function changes are markedly impacted by persistent sporadic denervation, making the mitochondrion a less viable therapeutic target.
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Affiliation(s)
- Sally Spendiff
- Research Institute of the McGill University Health Centre, Montreal, Canada.,McGill Research Centre for Physical Activity & Health, McGill University, Montreal, Canada
| | - Madhusudanarao Vuda
- Research Institute of the McGill University Health Centre, Montreal, Canada.,McGill Research Centre for Physical Activity & Health, McGill University, Montreal, Canada
| | - Gilles Gouspillou
- Research Institute of the McGill University Health Centre, Montreal, Canada.,Present address: Department of Kinanthropologie, Universite du Quebec a Montreal, Montreal, Canada
| | - Sudhakar Aare
- Research Institute of the McGill University Health Centre, Montreal, Canada.,McGill Research Centre for Physical Activity & Health, McGill University, Montreal, Canada
| | - Anna Perez
- Research Institute of the McGill University Health Centre, Montreal, Canada
| | - José A Morais
- Division of Geriatric Medicine, McGill University, Montreal, Canada
| | - Robert T Jagoe
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Canada
| | - Marie-Eve Filion
- Department of Kinesiology & Physical Education, McGill University, Montreal, Canada
| | - Robin Glicksman
- Department of Kinesiology & Physical Education, McGill University, Montreal, Canada
| | - Sophia Kapchinsky
- Department of Kinesiology & Physical Education, McGill University, Montreal, Canada
| | - Norah J MacMillan
- Department of Kinesiology & Physical Education, McGill University, Montreal, Canada
| | - Charlotte H Pion
- Present address: Department of Kinanthropologie, Universite du Quebec a Montreal, Montreal, Canada
| | - Mylène Aubertin-Leheudre
- Present address: Department of Kinanthropologie, Universite du Quebec a Montreal, Montreal, Canada
| | | | - José A Correa
- Department of Mathematics and Statistics, McGill University, Montreal, Canada
| | - Tanja Taivassalo
- McGill Research Centre for Physical Activity & Health, McGill University, Montreal, Canada.,Department of Kinesiology & Physical Education, McGill University, Montreal, Canada
| | - Russell T Hepple
- Research Institute of the McGill University Health Centre, Montreal, Canada.,McGill Research Centre for Physical Activity & Health, McGill University, Montreal, Canada.,Department of Kinesiology & Physical Education, McGill University, Montreal, Canada
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10
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Aare S, Spendiff S, Vuda M, Elkrief D, Perez A, Wu Q, Mayaki D, Hussain SNA, Hettwer S, Hepple RT. Failed reinnervation in aging skeletal muscle. Skelet Muscle 2016; 6:29. [PMID: 27588166 PMCID: PMC5007704 DOI: 10.1186/s13395-016-0101-y] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 08/05/2016] [Indexed: 12/08/2023] Open
Abstract
BACKGROUND Skeletal muscle displays a marked accumulation of denervated myofibers at advanced age, which coincides with an acceleration of muscle atrophy. METHODS In this study, we evaluated the hypothesis that the accumulation of denervated myofibers in advanced age is due to failed reinnervation by examining muscle from young adult (YA) and very old (VO) rats and from a murine model of sporadic denervation secondary to neurotrypsin over-expression (Sarco mouse). RESULTS Both aging rat muscle and Sarco mouse muscle exhibited marked fiber-type grouping, consistent with repeating cycles of denervation and reinnervation, yet in VO muscle, rapsyn at the endplate increased and was associated with only a 10 % decline in acetylcholine receptor (AChR) intensity, whereas in Sarco mice, there was a decline in rapsyn and a 25 % decrease in AChR intensity. Transcripts of muscle-specific kinase (21-fold), acetylcholine receptor subunits α (68-fold), ε (threefold) and γ (47-fold), neural cell adhesion molecule (66-fold), and runt-related transcription factor 1 (33-fold) were upregulated in VO muscle of the rat, consistent with the marked persistent denervation evidenced by a large proportion of very small fibers (>20 %). In the Sarco mice, there were much smaller increases in denervation transcripts (0-3.5-fold) and accumulation of very small fibers (2-6 %) compared to the VO rat, suggesting a reduced capacity for reinnervation in aging muscle. Despite the marked persistent denervation in the VO rat muscle, transcripts of neurotrophins involved in promoting axonal sprouting following denervation exhibited no increase, and several miRNAs predicted to suppress neurotrophins were elevated in VO rat. CONCLUSIONS Our results support the hypothesis that the accumulation of denervated fibers with aging is due to failed reinnervation and that this may be affected by a limited neurotrophin response that mediates axonal sprouting following denervation.
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Affiliation(s)
- Sudhakar Aare
- Research Institute of the McGill University Health Centre, EM2.2232, RI MUHC, 1001 Decarie Blvd, Montreal, QC Canada H4A 3J1 ; McGill Research Centre for Physical Activity and Health, McGill University, Montreal, QC Canada
| | - Sally Spendiff
- Research Institute of the McGill University Health Centre, EM2.2232, RI MUHC, 1001 Decarie Blvd, Montreal, QC Canada H4A 3J1 ; McGill Research Centre for Physical Activity and Health, McGill University, Montreal, QC Canada
| | - Madhusudanarao Vuda
- Research Institute of the McGill University Health Centre, EM2.2232, RI MUHC, 1001 Decarie Blvd, Montreal, QC Canada H4A 3J1 ; McGill Research Centre for Physical Activity and Health, McGill University, Montreal, QC Canada
| | - Daren Elkrief
- Research Institute of the McGill University Health Centre, EM2.2232, RI MUHC, 1001 Decarie Blvd, Montreal, QC Canada H4A 3J1 ; McGill Research Centre for Physical Activity and Health, McGill University, Montreal, QC Canada ; Department of Kinesiology and Physical Education, McGill University, Montreal, QC Canada
| | - Anna Perez
- Research Institute of the McGill University Health Centre, EM2.2232, RI MUHC, 1001 Decarie Blvd, Montreal, QC Canada H4A 3J1
| | - Qinghua Wu
- Research Institute of the McGill University Health Centre, EM2.2232, RI MUHC, 1001 Decarie Blvd, Montreal, QC Canada H4A 3J1 ; McGill Research Centre for Physical Activity and Health, McGill University, Montreal, QC Canada
| | - Dominique Mayaki
- Research Institute of the McGill University Health Centre, EM2.2232, RI MUHC, 1001 Decarie Blvd, Montreal, QC Canada H4A 3J1
| | - Sabah N A Hussain
- Research Institute of the McGill University Health Centre, EM2.2232, RI MUHC, 1001 Decarie Blvd, Montreal, QC Canada H4A 3J1
| | | | - Russell T Hepple
- Research Institute of the McGill University Health Centre, EM2.2232, RI MUHC, 1001 Decarie Blvd, Montreal, QC Canada H4A 3J1 ; McGill Research Centre for Physical Activity and Health, McGill University, Montreal, QC Canada ; Department of Kinesiology and Physical Education, McGill University, Montreal, QC Canada
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11
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Kang HG, Dingwell JB. Differential Changes with Age in Multiscale Entropy of Electromyography Signals from Leg Muscles during Treadmill Walking. PLoS One 2016; 11:e0162034. [PMID: 27570974 PMCID: PMC5003391 DOI: 10.1371/journal.pone.0162034] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2015] [Accepted: 07/13/2016] [Indexed: 11/26/2022] Open
Abstract
Age-related gait changes may be due to the loss of complexity in the neuromuscular system. This theory is disputed due to inconsistent results from single-scale analyses. Also, behavioral adaptations may confound these changes. We examined whether EMG dynamics during gait is less complex in older adults over a range of timescales using the multiscale entropy method, and whether slower walking attenuates this effect. Surface EMG was measured from the left vastus lateralis (VL), biceps femoris (BF), gastrocnemius (GA), and tibialis anterior (TA) in 17 young and 18 older adults as they walked on a treadmill for 5 minutes at 0.8x-1.2x of preferred speed. Sample entropy (SE) and the complexity index (CI) of the EMG signals were calculated after successive coarse-graining to extract dynamics at timescales of 27 to 270 Hz, with m = 2 and r = 0.15 SD. SE and CI were lower across the timescales in older adults in VL and BF, but higher in GA (all p<0.001); these results held for VL and GA even after accounting for longer EMG burst durations in older adults. CI was higher during slower walking speed in VL and BF (p<0.001). Results were mostly similar for m = 3 and r = 0.01-0.35. Smaller r was more sensitive to age-related differences. The decrease in complexity with aging in the timescales studied was limited to proximal muscles, particularly VL. The increase in GA may be driven by other factors. Walking slower may reflect a behavioral adaptation that allows the nervous system to function with greater complexity.
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Affiliation(s)
- Hyun Gu Kang
- Kinesiology, California State University San Marcos, San Marcos, California, United States of America
| | - Jonathan B. Dingwell
- Kinesiology and Health Education, University of Texas at Austin, Austin, Texas, United States of America
- Biomedical Engineering, University of Texas at Austin, Austin, Texas, United States of America
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12
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Hepple RT, Rice CL. Innervation and neuromuscular control in ageing skeletal muscle. J Physiol 2015; 594:1965-78. [PMID: 26437581 DOI: 10.1113/jp270561] [Citation(s) in RCA: 209] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 09/28/2015] [Indexed: 12/28/2022] Open
Abstract
Changes in the neuromuscular system affecting the ageing motor unit manifest structurally as a reduction in motor unit number secondary to motor neuron loss; fibre type grouping due to repeating cycles of denervation-reinnervation; and instability of the neuromuscular junction that may be due to either or both of a gradual perturbation in postsynaptic signalling mechanisms necessary for maintenance of the endplate acetylcholine receptor clusters or a sudden process involving motor neuron death or traumatic injury to the muscle fibre. Functionally, these changes manifest as a reduction in strength and coordination that precedes a loss in muscle mass and contributes to impairments in fatigue. Regular muscle activation in postural muscles or through habitual physical activity can attenuate some of these structural and functional changes up to a point along the ageing continuum. On the other hand, regular muscle activation in advanced age (>75 years) loses its efficacy, and at least in rodents may exacerbate age-related motor neuron death. Transgenic mouse studies aimed at identifying potential mechanisms of motor unit disruptions in ageing muscle are not conclusive due to many different mechanisms converging on similar motor unit alterations, many of which phenocopy ageing muscle. Longitudinal studies of ageing models and humans will help clarify the cause and effect relationships and thus, identify relevant therapeutic targets to better preserve muscle function across the lifespan.
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Affiliation(s)
- Russell T Hepple
- Department of Kinesiology & Physical Education, McGill University, Montreal, Québec, Canada.,McGill Research Centre for Physical Activity and Health, Montreal, Québec, Canada.,Centre for Translational Biology, Research Institute of the McGill University Health Centre, Montreal, Québec, Canada
| | - Charles L Rice
- School of Kinesiology, University of Western Ontario, London, Ontario, Canada.,Canadian Centre for Activity and Aging, London, Ontario, Canada.,Department of Anatomy & Cell Biology, University of Western Ontario, London, Ontario, Canada
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13
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Hepple RT. Mitochondrial involvement and impact in aging skeletal muscle. Front Aging Neurosci 2014; 6:211. [PMID: 25309422 PMCID: PMC4159998 DOI: 10.3389/fnagi.2014.00211] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 07/30/2014] [Indexed: 01/07/2023] Open
Abstract
Atrophy is a defining feature of aging skeletal muscle that contributes to progressive weakness and an increased risk of mobility impairment, falls, and physical frailty in very advanced age. Amongst the most frequently implicated mechanisms of aging muscle atrophy is mitochondrial dysfunction. Recent studies employing methods that are well-suited to interrogating intrinsic mitochondrial function find that mitochondrial respiration and reactive oxygen species emission changes are inconsistent between aging rat muscles undergoing atrophy and appear normal in human skeletal muscle from septuagenarian physically active subjects. On the other hand, a sensitization to permeability transition seems to be a general property of atrophying muscle with aging and this effect is even seen in atrophying muscle from physically active septuagenarian subjects. In addition to this intrinsic alteration in mitochondrial function, factors extrinsic to the mitochondria may also modulate mitochondrial function in aging muscle. In particular, recent evidence implicates oxidative stress in the aging milieu as a factor that depresses respiratory function in vivo (an effect that is not present ex vivo). Furthermore, in very advanced age, not only does muscle atrophy become more severe and clinically relevant in terms of its impact, but also there is evidence that this is driven by an accumulation of severely atrophied denervated myofibers. As denervation can itself modulate mitochondrial function and recruit mitochondrial-mediated atrophy pathways, future investigations need to address the degree to which skeletal muscle mitochondrial alterations in very advanced age are a consequence of denervation, rather than a primary organelle defect, to refine our understanding of the relevance of mitochondria as a therapeutic target at this more advanced age.
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Affiliation(s)
- Russell T Hepple
- Department of Kinesiology, McGill University Health Center, McGill University , Montreal, QC , Canada
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14
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Rudolf R, Khan MM, Labeit S, Deschenes MR. Degeneration of neuromuscular junction in age and dystrophy. Front Aging Neurosci 2014; 6:99. [PMID: 24904412 PMCID: PMC4033055 DOI: 10.3389/fnagi.2014.00099] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 05/08/2014] [Indexed: 12/27/2022] Open
Abstract
Functional denervation is a hallmark of aging sarcopenia as well as of muscular dystrophy. It is thought to be a major factor reducing skeletal muscle mass, particularly in the case of sarcopenia. Neuromuscular junctions (NMJs) serve as the interface between the nervous and skeletal muscular systems, and thus they may receive pathophysiological input of both pre- and post-synaptic origin. Consequently, NMJs are good indicators of motor health on a systemic level. Indeed, upon sarcopenia and dystrophy, NMJs morphologically deteriorate and exhibit altered characteristics of primary signaling molecules, such as nicotinic acetylcholine receptor and agrin. Since a remarkable reversibility of these changes can be observed by exercise, there is significant interest in understanding the molecular mechanisms underlying synaptic deterioration upon aging and dystrophy and how synapses are reset by the aforementioned treatments. Here, we review the literature that describes the phenomena observed at the NMJ in sarcopenic and dystrophic muscle as well as to how these alterations can be reversed and to what extent. In a second part, the current information about molecular machineries underlying these processes is reported.
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Affiliation(s)
- Rüdiger Rudolf
- Institute of Molecular and Cell Biology, University of Applied Sciences Mannheim , Mannheim , Germany ; Institute of Medical Technology, University of Heidelberg and University of Applied Sciences Mannheim , Mannheim , Germany ; Institute of Toxicology and Genetics, Karlsruhe Institute of Technology , Eggenstein-Leopoldshafen , Germany
| | - Muzamil Majid Khan
- Institute of Molecular and Cell Biology, University of Applied Sciences Mannheim , Mannheim , Germany ; Institute of Toxicology and Genetics, Karlsruhe Institute of Technology , Eggenstein-Leopoldshafen , Germany
| | - Siegfried Labeit
- Institute of Integrative Pathophysiology, University Medical Centre Mannheim , Mannheim , Germany
| | - Michael R Deschenes
- Department of Kinesiology and Health Sciences, The College of William and Mary , Williamsburg, VA , USA
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15
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Sierra E, Fernández A, de los Monteros AE, Arbelo M, de Quirós YB, Herráez P. Muscular senescence in cetaceans: adaptation towards a slow muscle fibre phenotype. Sci Rep 2014; 3:1795. [PMID: 23648412 PMCID: PMC3646281 DOI: 10.1038/srep01795] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 04/17/2013] [Indexed: 12/25/2022] Open
Abstract
Sarcopenia, or senile muscle atrophy, is the slow and progressive loss of muscle mass with advancing age that constitutes the most prevalent form of muscle atrophy. The effects of ageing on skeletal muscle have been extensively studied in humans and laboratory animals (mice), while the few reports on wild animals are based on short-lived mammals. The present study describes the age-related changes in cetacean muscles regarding the three factors that determine muscle mass: fibre size, fibre number, and fibre type. We show that the skeletal muscle fibres in cetaceans change with advancing age, evolving towards a slower muscle phenotype. We suggest that this physiological evolution constitutes an adaptation that allows these marine mammals to perform prolonged, deep dives.
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Affiliation(s)
- Eva Sierra
- Department of Veterinary Pathology, Institute of Animal Health, Veterinary School, Universidad de Las Palmas de Gran Canaria, Trasmontaña S/N, 35416 Arucas, Las Palmas, Spain.
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16
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Hindi SM, Mishra V, Bhatnagar S, Tajrishi MM, Ogura Y, Yan Z, Burkly LC, Zheng TS, Kumar A. Regulatory circuitry of TWEAK-Fn14 system and PGC-1α in skeletal muscle atrophy program. FASEB J 2013; 28:1398-411. [PMID: 24327607 DOI: 10.1096/fj.13-242123] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Skeletal muscle wasting attributed to inactivity has significant adverse functional consequences. Accumulating evidence suggests that peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) and TNF-like weak inducer of apoptosis (TWEAK)-Fn14 system are key regulators of skeletal muscle mass in various catabolic states. While the activation of TWEAK-Fn14 signaling causes muscle wasting, PGC-1α preserves muscle mass in several conditions, including functional denervation and aging. However, it remains unknown whether there is any regulatory interaction between PGC-1α and TWEAK-Fn14 system during muscle atrophy. Here we demonstrate that TWEAK significantly reduces the levels of PGC-1α and mitochondrial content (∼50%) in skeletal muscle. Levels of PGC-1α are significantly increased in skeletal muscle of TWEAK-knockout (KO) and Fn14-KO mice compared to wild-type mice on denervation. Transgenic (Tg) overexpression of PGC-1α inhibited progressive muscle wasting in TWEAK-Tg mice. PGC-1α inhibited the TWEAK-induced activation of NF-κB (∼50%) and dramatically reduced (∼90%) the expression of atrogenes such as MAFbx and MuRF1. Intriguingly, muscle-specific overexpression of PGC-1α also prevented the inducible expression of Fn14 in denervated skeletal muscle. Collectively, our study demonstrates that TWEAK induces muscle atrophy through repressing the levels of PGC-1α. Overexpression of PGC-1α not only blocks the TWEAK-induced atrophy program but also diminishes the expression of Fn14 in denervated skeletal muscle.
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Affiliation(s)
- Sajedah M Hindi
- 2Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, 500 South Preston St., Louisville, KY 40202, USA.
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17
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Gouspillou G, Picard M, Godin R, Burelle Y, Hepple RT. Role of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) in denervation-induced atrophy in aged muscle: facts and hypotheses. LONGEVITY & HEALTHSPAN 2013; 2:13. [PMID: 24472348 PMCID: PMC3922934 DOI: 10.1186/2046-2395-2-13] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 06/19/2013] [Indexed: 12/25/2022]
Abstract
Aging-related loss of muscle mass, a biological process named sarcopenia, contributes to mobility impairment, falls, and physical frailty, resulting in an impaired quality of life in older people. In view of the aging of our society, understanding the underlying mechanisms of sarcopenia is a major health-care imperative. Evidence obtained from human and rodent studies demonstrates that skeletal muscle denervation/reinnervation cycles occur with aging, and that progressive failure of myofiber reinnervation is a major cause of the accelerating phase of sarcopenia in advanced age. However, the mechanisms responsible for the loss of myofiber innervation with aging remain unknown. The two major strategies that counteract sarcopenia, that is, caloric restriction and endurance training, are well known to protect neuromuscular junction (NMJ) integrity, albeit through undefined mechanisms. Interestingly, both of these interventions better preserve PGC-1α expression with aging, a transcriptional coactivator which has recently been shown to regulate key proteins involved in maintaining NMJ integrity. We therefore propose that the aging-related decline in PGC-1α may be a central mechanism promoting instability of the NMJ and consequently, aging-related alterations of myofiber innervation in sarcopenia. Similarly, the promotion of PGC-1α expression by both caloric restriction and exercise training may be fundamental to their protective benefits for aging muscle by better preserving NMJ integrity.
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Affiliation(s)
| | | | | | | | - Russell T Hepple
- Department of Critical Care, McGill University Health Centre, 687 Pine Ave West, Montreal, QC H3A 1A1, Canada.
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18
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Kim JH, Thompson LV. Inactivity, age, and exercise: single-muscle fiber power generation. J Appl Physiol (1985) 2012; 114:90-8. [PMID: 23104693 DOI: 10.1152/japplphysiol.00525.2012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
We examined the effects of mild therapeutic exercise during a period of inactivity on size and contractile functions of myosin heavy chain (MHC) type I (n = 204) and type II (n = 419) single fibers from the medial gastrocnemius in three age groups. Young adult (5-12 mo), middle-aged (24-31 mo), and old (32-37 mo) F344BNF1 rats were assigned to one of three groups: weight-bearing control, non-weight bearing (NWB), and NWB plus exercise (NWBX). Fourteen days of hindlimb suspension were applied in NWB rats. The NWBX rats exercised on the treadmill for 15 min, four times a day, during the period of NWB. The NWBX did not improve peak power, but increased normalized power of MHC type I fibers in young adult rats. In MHC type II fibers, NWBX did not change peak power, isometric maximal force, V(max), and fiber size from young adult and middle-aged rats. NWBX did not improve peak power and isometric maximal force and showed a dramatic decline in V(max) and normalized power in the old rats. Collectively, mild treadmill exercise during a period of inactivity does not improve peak power of MHC type I or type II fiber from the gastrocnemius in young, middle-aged, and old rats. However, NWBX is beneficial in enhancing normalized power of MHC type I fibers in young adult rats, most likely due to the stimulus intensity and the ability of the individual fibers to adapt to the stimulus. In contrast, several factors, such as impaired adaptation potential, inappropriate exercise intensity, or increased susceptibility to muscle damage, may contribute to the lack of improvement in the older rats.
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Affiliation(s)
- Jong-Hee Kim
- Department of Physical Medicine and Rehabilitation, Medical School, University of Minnesota, Minneapolis, Minnesota 55455, USA
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19
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Dardevet D, Savary-Auzeloux I, Remond D, Mosoni L, Marzetti E, Buford TW, Bernabei R, Dionne IJ, Buford TW, Marzetti E, Manini TM, Buehring B, Kirchner E, Calabrese L, Manini TM, Clark BC, Fonseca HM, Delbono O, Taylor JR, Aubertin-Leheudre M, Barbat-Artigas S, Pion CH, Thornell LE, Gustafsson T, Cederholm T, Ulfhake B. Commentaries on Viewpoint: Muscle atrophy is not always sarcopenia. J Appl Physiol (1985) 2012; 113:680-4. [PMID: 22896680 PMCID: PMC4459919 DOI: 10.1152/japplphysiol.00667.2012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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20
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Kim JH, Thompson LV. Differential effects of mild therapeutic exercise during a period of inactivity on power generation in soleus type I single fibers with age. J Appl Physiol (1985) 2012; 112:1752-61. [PMID: 22422796 DOI: 10.1152/japplphysiol.01077.2011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The purpose of this study was to investigate the effects of mild therapeutic exercise (treadmill) in preventing the inactivity-induced alterations in contractile properties (e.g., power, force, and velocity) of type I soleus single fibers in three different age groups. Young adult (5- to 12-mo-old), middle-aged (24- to 31-mo-old), and old (32- to 40-mo-old) F344BNF1 rats were randomly assigned to three experimental groups: weight-bearing control (CON), non-weight bearing (NWB), and NWB with exercise (NWBX). NWB rats were hindlimb suspended for 2 wk, representing inactivity. The NWBX rats were hindlimb suspended for 2 wk and received therapeutic exercise on a treadmill four times a day for 15 min each. Peak power and isometric maximal force were reduced following hindlimb suspension (HS) in all three age groups. HS decreased fiber diameter in young adult and old rats (-21 and -12%, respectively). Specific tension (isometric maximal force/cross-sectional area) was significantly reduced in both the middle-aged (-36%) and old (-23%) rats. The effects of the mild therapeutic exercise program on fiber diameter and contractile properties were age specific. Mild treadmill therapeutic exercise attenuated the HS-induced reduction in fiber diameter (+17%, 93% level of CON group) and peak power (μN·fiber length·s(-1)) (+46%, 63% level of CON group) in young adult rats. In the middle-aged animals, this exercise protocol improved peak power (+60%, 100% level of CON group) and normalized power (kN·m(-2)·fiber length·s(-1)) (+45%, 108% level of CON group). Interestingly, treadmill exercise resulted in a further reduction in shortening velocity (-42%, 67% level of CON group) and specific tension (-29%, 55% level of CON group) in the old animals. These results suggest that mild treadmill exercise is beneficial in attenuating and preventing inactivity-induced decline in peak power of type I soleus single fibers in young adult and middle-aged animals, respectively. However, this exercise program does not prevent the HS-induced decline in muscle function in the old animals.
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Affiliation(s)
- Jong-Hee Kim
- Department of Physical Medicine and Rehabilitation, Medical School, University of Minnesota, Minneapolis, Minnesota 55455, USA
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21
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Denervation causes fiber atrophy and myosin heavy chain co-expression in senescent skeletal muscle. PLoS One 2012; 7:e29082. [PMID: 22235261 PMCID: PMC3250397 DOI: 10.1371/journal.pone.0029082] [Citation(s) in RCA: 171] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 11/21/2011] [Indexed: 01/06/2023] Open
Abstract
Although denervation has long been implicated in aging muscle, the degree to which it is causes the fiber atrophy seen in aging muscle is unknown. To address this question, we quantified motoneuron soma counts in the lumbar spinal cord using choline acetyl transferase immunhistochemistry and quantified the size of denervated versus innervated muscle fibers in the gastrocnemius muscle using the in situ expression of the denervation-specific sodium channel, Nav1.5, in young adult (YA) and senescent (SEN) rats. To gain insights into the mechanisms driving myofiber atrophy, we also examined the myofiber expression of the two primary ubiquitin ligases necessary for muscle atrophy (MAFbx, MuRF1). MN soma number in lumbar spinal cord declined 27% between YA (638±34 MNs×mm−1) and SEN (469±13 MNs×mm−1). Nav1.5 positive fibers (1548±70 μm2) were 35% smaller than Nav1.5 negative fibers (2367±78 μm2; P<0.05) in SEN muscle, whereas Nav1.5 negative fibers in SEN were only 7% smaller than fibers in YA (2553±33 μm2; P<0.05) where no Nav1.5 labeling was seen, suggesting denervation is the primary cause of aging myofiber atrophy. Nav1.5 positive fibers had higher levels of MAFbx and MuRF1 (P<0.05), consistent with involvement of the proteasome proteolytic pathway in the atrophy of denervated muscle fibers in aging muscle. In summary, our study provides the first quantitative assessment of the contribution of denervation to myofiber atrophy in aging muscle, suggesting it explains the majority of the atrophy we observed. This striking result suggests a renewed focus should be placed on denervation in seeking understanding of the causes of and treatments for aging muscle atrophy.
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22
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Xu J, Hwang JCY, Lees HA, Wohlgemuth SE, Knutson MD, Judge AR, Dupont-Versteegden EE, Marzetti E, Leeuwenburgh C. Long-term perturbation of muscle iron homeostasis following hindlimb suspension in old rats is associated with high levels of oxidative stress and impaired recovery from atrophy. Exp Gerontol 2011; 47:100-8. [PMID: 22085543 DOI: 10.1016/j.exger.2011.10.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Revised: 10/06/2011] [Accepted: 10/28/2011] [Indexed: 11/26/2022]
Abstract
In the present study, we investigated the effects of 7 and 14 days of re-loading following 14-day muscle unweighting (hindlimb suspension, HS) on iron transport, non-heme iron levels and oxidative damage in the gastrocnemius muscle of young (6 months) and old (32 months) male Fischer 344×Brown Norway rats. Our results demonstrated that old rats had lower muscle mass, higher levels of total non-heme iron and oxidative damage in skeletal muscle in comparison with young rats. Non-heme iron concentrations and total non-heme iron amounts were 3.4- and 2.3-fold higher in aged rats as compared with their young counterparts, respectively. Seven and 14 days of re-loading was associated with higher muscle weights in young animals as compared with age-matched HS rats, but there was no difference in muscle weights among aged HS, 7 and 14 days of re-loading rats, indicating that aged rats may have a lower adaptability to muscle disuse and a lower capacity to recover from muscle atrophy. Protein levels of cellular iron transporters, such as divalent metal transport-1 (DMT1), transferrin receptor-1 (TfR1), Zip14, and ferroportin (FPN), and their mRNA abundance were determined. TfR1 protein and mRNA levels were significantly lower in aged muscle. Seven and 14 days of re-loading were associated with higher TfR1 mRNA and protein levels in young animals in comparison with their age-matched HS counterparts, but there was no difference between cohorts in aged animals, suggesting adaptive responses in the old to cope with iron deregulation. The extremely low expression of FPN in skeletal muscle might lead to inefficient iron export in the presence of iron overload and play a critical role in age-related iron accumulation in skeletal muscle. Moreover, oxidative stress was much greater in the muscles of the older animals measured as 4-hydroxy-2-nonhenal (HNE)-modified proteins and 8-oxo-7,8-dihydroguanosine levels. These markers remained fairly constant with either HS or re-loading in young rats. In old rats, HNE-modified proteins and 8-oxo-7,8-dihydroguanosine levels were markedly higher in HS and were lower after 7 days of recovery. However, no difference was observed following 14 days of recovery between control and re-loading animals. In conclusion, advanced age is associated with disruption of muscle iron metabolism which is further perturbed by disuse and persists over a longer time period.
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Affiliation(s)
- Jinze Xu
- Department of Aging and Geriatric Research, Division of Biology of Aging, Genomics and Biomarkers Core of The Institute on Aging, University of Florida, Gainesville, Florida 32611, USA.
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