Maintaining motor units into old age: running the final common pathway

Power, Geoffrey A.; Dalton, Brian H.; Gilmore, Kevin J.; Allen, Matti D.; Doherty, Timothy J.; Rice, Charles L.

doi:10.4081/ejtm.2017.6597

Cited by 28 publications

(12 citation statements)

References 17 publications

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“…In contrast, MA tended to have a lower abundance of NCAM positive fibres and did not have an elevated abundance of pyknotic nuclei compared to YI, suggesting a milder impact of persistent denervation with ageing in these highly functioning individuals. This is consistent with our previous analysis, showing that world class octogenarian MA men and women (the same women studied here in the MA group) exhibit a greater retention of motor unit number estimates in their tibialis anterior muscle than healthy non-athlete octogenarian controls (Power et al 2016(Power et al , 2017.…”

Section: Denervation and Fibre Type Groupingsupporting

confidence: 93%

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Fidelity of muscle fibre reinnervation modulates ageing muscle impact in elderly women

Sonjak

Jacob

Morais

et al. 2019

The Journal of Physiology

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Key points Susceptibility to age‐related muscle atrophy relates to the degree of muscle denervation and the capacity of successful reinnervation. However, the specific role of denervation as a determinant of the severity of muscle aging between populations with low versus high physical function has not been addressed. We show that prefrail/frail elderly women exhibited marked features of muscle denervation, whereas world class octogenarian female master athletes showed attenuated indices of denervation and greater reinnervation capacity. These findings suggest that the difference in age‐related muscle impact between low‐ and high‐functioning elderly women is the robustness of the response to denervation of myofibers. Abstract Ageing muscle degeneration is a key contributor to physical frailty; however, the factors responsible for exacerbated vs. muted ageing muscle impact are largely unknown. Based upon evidence that susceptibility to neurogenic impact is an important determinant of the severity of ageing muscle degeneration, we aimed to determine the presence and extent of denervation in pre‐frail/frail elderly (FE, 77.9 ± 6.2 years) women compared to young physically inactive (YI, 24.0 ± 3.5 years) females, and contrast these findings to high‐functioning world class octogenarian female masters athletes (MA, 80.9 ± 6.6 years). Muscle biopsies from vastus lateralis muscle were obtained from all three groups to assess denervation‐related morphological and transcriptional markers. The FE group displayed marked grouping of slow fibres, accumulation of very small myofibres, a severe reduction in type IIa/I size ratio, highly variable inter‐subject accumulation of neural cell adhesion molecule (NCAM)‐positive myofibres, and an accumulation of pyknotic nuclei, indicative of recurring cycles of denervation/reinnervation and persistent denervation. The MA group exhibited a smaller decline in type IIa/I size ratio and fewer pyknotic nuclei, accompanied by a higher degree of type I fibre grouping and larger fibre group size, suggesting a greater reinnervation of denervated fibres. Consistent with this interpretation, MA had higher mRNA levels of the reinnervation‐promoting cytokine fibroblast growth factor binding protein 1 (FGFBP1) than FE. Our results indicate that the muscle of FE women has significant neurogenic atrophy, whereas MA muscle exhibit superior reinnervation capacity, suggesting that the difference in age‐related muscle impact between low‐ and high‐functioning elderly women is the robustness of the response to denervation of myofibres.

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Section: Denervation and Fibre Type Groupingsupporting

confidence: 93%

“…This is consistent with our previous analysis, showing that world class octogenarian MA men and women (the same women studied here in the MA group) exhibit a greater retention of motor unit number estimates in their tibialis anterior muscle than healthy non‐athlete octogenarian controls (Power et al . , ).…”

Section: Discussionmentioning

confidence: 99%

Fidelity of muscle fibre reinnervation modulates ageing muscle impact in elderly women

Sonjak

Jacob

Morais

et al. 2019

The Journal of Physiology

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“…By necessity, much of what is known about human spinal MN adaptations to physical activity comes from indirect measures made using surface or intramuscular electromyography. These indirect measures are made to infer changes in number of MUs (Power et al 2010a(Power et al , 2012(Power et al , 2017, MU structure (e.g., neuromuscular junction) (Nishimune et al 2014), intrinsic MN properties such as PIC and AHP (Gorassini et al 2002a), and MU output characteristics such as firing rates and nonlinear firing behaviour (e.g., force-frequency relationship) (Heckman and Enoka 2012), and recruitment thresholds (Gorassini et al 2002b). Activity-induced plasticity is elicited using cross-sectional study designs (e.g., physically active or trained vs. sedentary controls) as well as exercise and disuse interventions.…”

Section: Approaches Used To Study Activity-induced Mn Adaptations In mentioning

confidence: 99%

Understanding exercise-dependent plasticity of motoneurons using intracellular and intramuscular approaches

Button

Kalmar

2019

Appl. Physiol. Nutr. Metab.

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Spinal motoneurons (MN) exhibit exercise-dependent adaptations to increased activity, such as exercise and locomotion, as well as decreased activity associated with disuse, spinal cord injury, and aging. The development of several experimental approaches, in both human and animal models, has contributed significantly to our understanding of this plasticity. The purpose of this review is to summarize how intracellular recordings in an animal model and motor unit recordings in a human model have, together, contributed to our current understanding of exercise-dependent MN plasticity. These approaches and techniques will allow neuroscientists to continue to advance our understanding of MN physiology and the plasticity of the "final common path" of the motor system, and to design experiments to answer the critical questions that are emerging in this field.Résumé : Les motoneurones spinaux (MN) présentent des adaptations liées à l'augmentation de l'activité telle qu'à l'exercice physique et à la locomotion et d'autres adaptations à diminution de l'activité associée à la désuétude, aux lésions médullaires et au vieillissement. Le développement de plusieurs approches expérimentales à la fois chez l'homme et chez l'animal a grandement contribué à notre compréhension de cette plasticité. Le but de cette analyse documentaire est de présenter de façon sommaire comment les enregistrements intracellulaires dans un modèle animal et les enregistrements d'unités motrices dans un modèle humain ont ensemble favoriser notre compréhension actuelle de la plasticité du MN liée à l'exercice. Ces approches et techniques permettront aux neuroscientifiques de continuer à approfondir la compréhension de la physiologie du MN et de la plasticité de la « voie commune terminale » du système moteur ainsi que de concevoir des expérimentations pour répondre aux questions critiques qui se posent dans ce domaine. [Traduit par la Rédaction] Mots-clés : unité motrice, désuétude, locomotion, animal, humain. Experimental approaches used to study MN properties and MU functionSince the development of intracellular MN recordings by Sir John Eccles during the 1950s (Brock et al. 1952(Brock et al. , 1953Coombs et al.

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“…This has become a very important research topic during the subsequent years [10]. So given this history, it will not be a surprise to find that the Collection of Abstracts of the 2017 Spring PaduaMuscleDays covers a new discovery on the mechanisms of Ca 2+ handling at ultrastructural level and spans to cover work on take-home rehabilitation strategies to rejuvenate older old humans [11][12][13][14][15][16][17][18][19][20][21][22][23]. Additional information is in the 2017SpPMD PROMO at: https://www.youtube.com/watch?v=NdbbeQFi9z8&t=4s and in the new Youtube Channel: https://www.youtube.com/channel/ UCshXMdDxpuOKa7eCWMBRqLg/videos?sort=dd&view=0&shelf_ id=0 The conference is, indeed, expanding beyond the boundaries of time and walls to include the internet and social media.…”

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confidence: 99%

From BAM to BEM, a personal journey through EJTM and PaduaMuscleDays

Carraro¹

2017

Biol Eng Med

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As a young researcher I had the only option to work on molecular myology at the University of Padova, Italy. This took me to develop special expertise in muscle proteins analyses at molecular levels. Introduced to the study of muscle denervation/reinnervation I started a research project on long term denervated muscle, whose management continues to be my primary interest. On the way, I started a series of rehabilitation conferences in Terme Euganee, Padua, Italy and founded a dedicated journal to basic research and eventual application of muscle studies, i.e., "Basic and Applied Myology" (BAM). From 2010 the journal changed name to "European Journal of Translational Myology" (EJTM), whose contents are limited to Myology, though their implications are of foremost importance in several neurological disorders, in aging and in oncology. Thus, I was attracted by, and I am proud to contribute to "Biology, Engineering and Medicine" (BEM) that extends its contents to the full range of medical problems and eventual solutions by means of interactions of biology and technology to manage medical problems.

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Maintaining motor units into old age: running the final common pathway

Cited by 28 publications

References 17 publications

Fidelity of muscle fibre reinnervation modulates ageing muscle impact in elderly women

Fidelity of muscle fibre reinnervation modulates ageing muscle impact in elderly women

Understanding exercise-dependent plasticity of motoneurons using intracellular and intramuscular approaches

From BAM to BEM, a personal journey through EJTM and PaduaMuscleDays

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