Exercise‐induced muscle growth is muscle‐specific and age‐dependent

Leiter, Jeff; Peeler, Jason; Anderson, Judy E.

doi:10.1002/mus.21965

Cited by 39 publications

(37 citation statements)

References 57 publications

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“…Half the mice had access to a voluntary running wheel for voluntary exercise (Ex) for the first 3 wk of the treatment period, as reported (5). A previous study showed quadriceps from 18-mo mice were refractory to hypertrophy following 3 wk of voluntary exercise, whereas younger 8-mo mice were responsive (44); this experiment tested whether NO-donor treatment could change the responsiveness to exercise and induce muscle growth in the 18-mo group. Groups were control (C, oil only, n ϭ 6), Ex (n ϭ 8), I (n ϭ 4), and I ϩ Ex (n ϭ 3).…”

Section: Methodsmentioning

confidence: 95%

“…Muscle wasting results from atrophy of individual fibers, loss and expansion of motor units (24, 37, 79) that becomes increasingly severe from late-middle age to senescence in both fast-and slow-twitch muscles (63) and ultimately weakness limits function and quality of life. Current treatments, such as exercise and growth-promoting drugs, are not completely effective, in part as we do not fully understand the many facets of age-related atrophy.Progressive refractoriness of satellite cells (SC) to stimuli that promote growth in young mice, such as stretch (43) and exercise (36,44,45), is a major contributor to age-related atrophy. Muscle SC are required to maintain mass and repair muscle and are involved in growth via proliferation (4).…”

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confidence: 99%

“…Progressive refractoriness of satellite cells (SC) to stimuli that promote growth in young mice, such as stretch (43) and exercise (36,44,45), is a major contributor to age-related atrophy. Muscle SC are required to maintain mass and repair muscle and are involved in growth via proliferation (4).…”

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confidence: 99%

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Nitric oxide and voluntary exercise together promote quadriceps hypertrophy and increase vascular density in female 18-mo-old mice

Leiter

Upadhaya²,

Anderson

2012

American Journal of Physiology-Cell Physiology

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Age-related sarcopenia reduces the size, strength, and function of muscle, and the diameter of muscle fibers. It also disrupts the dystrophin-glycoprotein complex, dislocating nitric oxide synthase 1 (NOS-1) and reducing sarcolemmal integrity. This study of quadriceps muscle in 18-mo-old mice showed that NO-donor treatment with isosorbide dinitrate (I) for 6 wk, in combination with voluntary exercise for 3 wk, increased muscle mass by 25% and stimulated cell proliferation. The resulting fiber hypertrophy was accompanied by a lower ratio of protein:DNA, consistent with myogenic-cell hyperplasia. Treatment enhanced the ratio of NOS-1:β-dystroglycan in correlation with fiber diameter, improved sarcolemmal integrity, and increased vascular density after an increase in vascular endothelial growth factor protein at 3 wk. Results demonstrate that age-related muscle refractoriness to exercise can be overcome with NO-donor treatment. Since activation of muscle stem cells and vascular perfusion are limiting factors in the maintenance, regeneration, and growth of aged muscle, results suggest the feasibility of using NO-donor drugs to combat atrophy and muscle ischemia. Improved function and quality of life from the NO-amplified effects of exercise may be useful in aging and other conditions such as disuse, insulin resistance, or microgravity.

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Section: Methodsmentioning

confidence: 95%

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confidence: 99%

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Nitric oxide and voluntary exercise together promote quadriceps hypertrophy and increase vascular density in female 18-mo-old mice

Leiter

Upadhaya²,

Anderson

2012

American Journal of Physiology-Cell Physiology

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“…We and others have previously observed a blunted hypertrophic response in older females following long-term RT (Bamman et al, 2003;Ivey et al, 2000;Kosek et al, 2006). Although the underlying mechanism has not been well-defined, the divergent extent of hypertrophy in old females may occur in part from reduced myogenic aptitude (Gallegly et al, 2004;Leiter et al, 2011), which could conceivably impair the regenerative processes activated in response to mechanical loading.…”

Section: Introductionmentioning

confidence: 91%

β-Hydroxy-β-Methylbutyrate Did Not Enhance High Intensity Resistance Training-Induced Improvements in Myofiber Dimensions and Myogenic Capacity in Aged Female Rats

Kim

Park

Lee

et al. 2012

Molecules and Cells

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Older women exhibit blunted skeletal muscle hypertrophy following resistance training (RT) compared to other age and gender cohorts that is partially due to an impaired regenerative capacity. In the present study, we examined whether β-hydroxy-β-methylbutyrate (HMB) provision to aged female rodents would enhance regenerative mechanisms and facilitate RT-induced myofiber growth. Nineteen-month old female Sprague-Dawley rats were randomly divided into three groups: HMB (0.48 g/kg/d; n = 6), non-HMB (n = 6), and control (n = 4). HMB and non-HMB groups underwent RT every third day for 10 weeks using a ladder climbing apparatus. Whole body strength, grip strength, and body composition was evaluated before and after RT. The gastrocnemius and soleus muscles were analyzed using magnetic resonance diffusion tensor imaging, RT-PCR, and immunohistochemistry to determine myofiber dimensions, transcript expression, and satellite cells/myonuclei, respectively. ANOVAs were used with significance set at p < 0.05. There were significant time effects (pre vs. post) for whole body strength (+262%), grip strength (+17%), lean mass (+20%), and fat mass (-19%). Both RT groups exhibited significant increases in the mean myofiber cross-sectional area (CSA) in the gastrocnemius and soleus (+8-22%) compared to control. Moreover, both groups demonstrated significant increases in the numbers of satellite cells (+100-108%) and myonuclei (+32%) in the soleus but not the gastrocnemius. A significant IGF-I mRNA elevation was only observed in soleus of the HMB group (+33%) whereas MGF and myogenin increased significantly in both groups (+32-40%). Our findings suggest that HMB did not further enhance intense RT-mediated myogenic mechanisms and myofiber CSA in aged female rats.

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“…Muscle mass is strictly regulated by various factors and can adapt to physical exertion by increasing the amount and size of contractile proteins (Leiter et al 2011). One of the most powerful negative regulators of muscle growth is myostatin (McPherron and Lee 1997).…”

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confidence: 99%

A single nucleotide polymorphism in exon 3 of the myostatin gene in different breeds of domestic pigeon (Columba livia var. domestica) 32

Dybus¹,

Proskura²,

Sadkowski³

et al. 2013

Vet. Med. - Czech

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ABSTRACT:Myostatin is considered to be one of the most powerful negative regulators of muscle growth. The lack of a functional myostatin (MSTN) or its mutation can result in uncommon musculature like "double-muscling" in Belgian Blue cattle. Recent studies on MSTN variability indicate its relationship with racing performance in dogs and racehorses. Considering the high homology of MSTN among the vertebrates, there are grounds to suppose that the same correlation will occur in pigeons. The aim of this study was to analyse MSTN variability in several pigeon breeds raised for different purposes. The PCR-RFLP method was used for genotyping the C → T silent substitution in exon 3 of the MSTN gene. A total of 376 domestic pigeons (Columba livia var. domestica) were genotyped. The differences in genotype frequencies (P < 0.01) and allele frequencies (P < 0.01), between the studied groups were observed. Minor allele (MSTN T ) frequency was the highest in the group of utility pigeons (0.291), which are characterised by abundant muscle mass and higher body mass-to-muscle mass ratio. Further studies should be performed in order to determine the impact of the SNP analysed in the present paper on the amount of functional myostatin in muscles.

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Exercise‐induced muscle growth is muscle‐specific and age‐dependent

Abstract: Exercise-induced activation of SCs and regulation of gene expression are muscle-specific and age-dependent. Perturbed sensitivity to exercise in older mice provides insight into sarcopenia and potential treatments.

Cited by 39 publications

References 57 publications

Nitric oxide and voluntary exercise together promote quadriceps hypertrophy and increase vascular density in female 18-mo-old mice

Nitric oxide and voluntary exercise together promote quadriceps hypertrophy and increase vascular density in female 18-mo-old mice

β-Hydroxy-β-Methylbutyrate Did Not Enhance High Intensity Resistance Training-Induced Improvements in Myofiber Dimensions and Myogenic Capacity in Aged Female Rats

A single nucleotide polymorphism in exon 3 of the myostatin gene in different breeds of domestic pigeon (Columba livia var. domestica) 32

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