Myonuclear number and myosin heavy chain expression in rat soleus single muscle fibers after spaceflight

Allen, David L.; Yasui, Wataru; Tanaka, Takato; Ohira, Yoshinobu; Nagaoka, Shunji; Sekiguchi, Chiharu; Hinds, William E.; Roy, Roland R.; Edgerton, V. Reggie

doi:10.1152/jappl.1996.81.1.145

Cited by 172 publications

(203 citation statements)

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“…5) [76]. The results indicated that the percent distribution of fibers which expressed only slow MHC apparently decreased, and some of the slow fibers began to co-express some fast MHC as well.…”

Section: Fiber Phenotypementioning

confidence: 93%

Neuromuscular Adaptation to Microgravity Environment.

Ohira

2000

JJP

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The pattern of muscle activity influences the morphological, metabolic, and contractile properties of skeletal muscles. For example, the metabolic capacity of muscles is affected specifically by the type of exercise training [1][2][3]. Increased activity or over-loading by removing the synergists causes a compensatory hypertrophy [4][5][6][7][8][9][10][11]. Hypertrophy is also induced by the stretching of matured muscles in vivo [12,13] and cultured myotubes and fibroblasts [14][15][16][17]. Exercise-induced metabolic adaptation of muscles is lost when exercise training is stopped [18]. Further, muscle atrophy is induced by denervation [10,19], spinal cord transection [20], joint immobilization [21][22][23], tenotomy [24,25], spaceflight [26][27][28][29], and/or hindlimb suspension [29][30][31][32]. Most of these models are generally presumed to be models of reduced neuromuscular activity. But the level of use may not be the only factor involved in the atrophic process.There is a close association in the physiological, biochemical, and morphological properties between a motoneuron and the muscle fibers it innervates [1]. Studies to support this view are those in which chronic electrical stimulation at low frequency (1-10 Hz) changes the properties of fast-twitch muscles toward those of slow-twitch muscles [33][34][35][36][37][38].Some of the characteristics of muscle fibers are also altered following cross-innervation [39][40][41][42]. Buller et al. [40] suggested that the neural influence on muscle could be due to neurotrophic effect as well as via nerve impulses. Muscular Responses to Gravitational Unloading Morphological propertiesGravitational unloading by exposure to weightlessness [26][27][28][29][43][44][45][46][47] and/or its simulation model, hindlimb suspension [29][30][31][32][48][49][50][51][52][53][54][55][56], causes rapid atrophy in muscles, such as soleus and adductor longus, that are composed predominantly of slow fibers. The cross-sectional areas (CSAs) of both slow-and fasttwitch fibers of rats were less after 14 d of spaceflight and hindlimb suspension than those in the agematched controls [29]. But the degree of atrophy was greater in slow-than fast-twitch fibers [28,29]. Therefore, muscles composed of predominantly slow fibers are more susceptible to atrophy [26,28, 47]. The weights of fast-twitch ankle dorsi-flexors, such as the tibialis anterior (TA) and extensor digitorum longus (EDL), are also generally less after unloading than those of age-matched controls [31, 57]. But these were Japanese Journal of Physiology, 50, 303-314, 2000 Key words: atrophy, fiber-type transformation, contractile properties, neural responses, microgravity.Abstract: Morphological and/or functional characteristics of skeletal muscles have a greater adaptability in response to changes in environmental stimuli. For example, an atrophy associated with a shift of fiber characteristics toward fast-twitch type is a common adaptation of antigravity muscle to a microgravity environment. Neuromuscular responses and ...

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Section: Fiber Phenotypementioning

confidence: 93%

Neuromuscular Adaptation to Microgravity Environment.

Ohira

2000

JJP

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“…It is generally accepted that muscle hypertrophy is related to an increased myonuclear number through activation of satellite cells (Kadi et al, 2005;Mackey et al, 2007), while muscular atrophy is related to an apoptotic decrease in myonuclear number (Allen et al, 1997a,b;Alway & Siu, 2008). However, there are several reports demonstrating a less stringent relationship between myonuclear number and fibre size, i.e., there are reports of muscle fibre hypertrophy without satellite cell activation (McCarthy & Esser, 2007) as well as atrophy accompanied by either an increased, decreased or unaltered number of myonuclei (Allen et al, 1995(Allen et al, , 1996(Allen et al, , 1997aKasper & Xun, 1996;Gundersen & Bruusgaard, 2008).…”

Section: Introductionmentioning

confidence: 99%

Effects of aging and gender on the spatial organization of nuclei in single human skeletal muscle cells

et al. 2010

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SummaryThe skeletal muscle fibre is a syncitium where each myonucleus regulates the gene products in a finite volume of the cytoplasm, i.e., the myonuclear domain (MND). We analysed aging-and gender-related effects on myonuclei organization and the MND size in single muscle fibres from six young (21-31 years) and nine old men (72-96 years), and from six young (24-32 years) and nine old women (65-96 years), using a novel image analysis algorithm applied to confocal images. Muscle fibres were classified according to myosin heavy chain (MyHC) isoform expression. Our image analysis algorithm was effective in determining the spatial organization of myonuclei and the distribution of individual MNDs along the single fibre segments. Significant linear relations were observed between MND size and fibre size, irrespective age, gender and MyHC isoform expression. The spatial organization of individual myonuclei, calculated as the distribution of nearest neighbour distances in 3D, and MND size were affected in old age, but changes were dependent on MyHC isoform expression. In type I muscle fibres, average NN-values were lower and showed an increased variability in old age, reflecting an aggregation of myonuclei in old age. Average MND size did not change in old age, but there was an increased MND size variability. In type IIa fibres, average NN-values and MND sizes were lower in old age, reflecting the smaller size of these muscle fibres in old age. It is suggested that these changes have a significant impact on protein synthesis and degradation during the aging process.

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“…The muscle fiber type is known to change during atrophy according to the causes that trigger the atrophy. For example, disuse muscular atrophy that arises according to the fixed-joint or dangling hind-leg model exhibits a decrease in type I fibers and an increase in type II fibers 34,35) . MyoD and HMGCoA-reductase inhibition have been suggested to participate in myosin 36,37) .…”

Section: Changes In Muscle Type During Atrophymentioning

confidence: 99%

Clinical definition and diagnostic criteria for sarcopenia

Udaka

Fukuda

Yamauchi

et al. 2014

JPFSM

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The occurrence of sarcopenia and muscular dystrophy with aging has attracted attention. Many factors are reported as causes of sarcopenia, such as the functional decline of a digestive organ occurring with aging and malnutrition due to a decrease in food intake. Also, a decrease in growth hormone and an increase in cytokines are also considered to be causes of sarcopenia. Meanwhile, the differentiation between sarcopenia and disuse muscle atrophy is not clear. It will be important in future studies to clearly define the differences between sarcopenia and disuse muscle atrophy. Recently, the diagnostic criteria of sarcopenia have been defined according to a large-scale investigation. In the future, an easier sarcopenia diagnostic method should be developed. It is necessary to design specific treatment strategies more closely correlated to the clinical condition of individual patients, because the causes of sarcopenia vary widely. In this review, we summarize the characteristics of the clinical condition, diagnosis, and treatment of sarcopenia.

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Myonuclear number and myosin heavy chain expression in rat soleus single muscle fibers after spaceflight

Cited by 172 publications

References 0 publications

Neuromuscular Adaptation to Microgravity Environment.

Neuromuscular Adaptation to Microgravity Environment.

Effects of aging and gender on the spatial organization of nuclei in single human skeletal muscle cells

Clinical definition and diagnostic criteria for sarcopenia

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