Contractile efficiency of dystrophic mdx mouse muscle: in vivo and ex vivo assessment of adaptation to exercise of functional end points

2017 ◽  
Vol 122 (4) ◽  
pp. 828-843 ◽  
Author(s):  
Roberta Francesca Capogrosso ◽  
Paola Mantuano ◽  
Anna Cozzoli ◽  
Francesca Sanarica ◽  
Ada Maria Massari ◽  
...  
Keyword(s):  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Muscle Damage ◽  
Functional Adaptation ◽  
Mdx Mouse ◽  
Mdx Mice ◽  
Chronic Exercise ◽  
Exercise Protocol ◽  
Dystrophic Muscle

Progressive weakness is a typical feature of Duchenne muscular dystrophy (DMD) patients and is exacerbated in the benign mdx mouse model by in vivo treadmill exercise. We hypothesized a different threshold for functional adaptation of mdx muscles in response to the duration of the exercise protocol. In vivo weakness was confirmed by grip strength after 4, 8, and 12 wk of exercise in mdx mice. Torque measurements revealed that exercise-related weakness in mdx mice correlated with the duration of the protocol, while wild-type (WT) mice were stronger. Twitch and tetanic forces of isolated diaphragm and extensor digitorum longus (EDL) muscles were lower in mdx compared with WT mice. In mdx, both muscle types exhibited greater weakness after a single exercise bout, but only in EDL after a long exercise protocol. As opposite to WT muscles, mdx EDL ones did not show any exercise-induced adaptations against eccentric contraction force drop. qRT-PCR analysis confirmed the maladaptation of genes involved in metabolic and structural remodeling, while damage-related genes remained significantly upregulated and angiogenesis impaired. Phosphorylated AMP kinase level increased only in exercised WT muscle. The severe histopathology and the high levels of muscular TGF-β1 and of plasma matrix metalloproteinase-9 confirmed the persistence of muscle damage in mdx mice. Therefore, dystrophic muscles showed a partial degree of functional adaptation to chronic exercise, although not sufficient to overcome weakness nor signs of damage. The improved understanding of the complex mechanisms underlying maladaptation of dystrophic muscle paves the way to a better managment of DMD patients. NEW & NOTEWORTHY We focused on the adaptation/maladaptation of dystrophic mdx mouse muscles to a standard protocol of exercise to provide guidance in the development of more effective drug and physical therapies in Duchenne muscular dystrophy. The mdx muscles showed a modest functional adaptation to chronic exercise, but it was not sufficient to overcome the progressive in vivo weakness, nor to counter signs of muscle damage. Therefore, a complex involvement of multiple systems underlies the maladaptive response of dystrophic muscle.

scholarly journals Mitochondrial content is preserved throughout disease progression in the mdx mouse model of Duchenne muscular dystrophy, regardless of taurine supplementation

2018 ◽  
Vol 314 (4) ◽  
pp. C483-C491 ◽  
Author(s):  
Robert G. Barker ◽  
Victoria L. Wyckelsma ◽  
Hongyang Xu ◽  
Robyn M. Murphy
Keyword(s):  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Muscle Damage ◽  
Disease Severity ◽  
Mitochondrial Dynamics ◽  
Mdx Mouse ◽  
Mdx Mice ◽  
Protein Abundance ◽  
Mitochondrial Content ◽  
Edl Muscle

Mitochondrial dysfunction is a pathological feature of Duchenne muscular dystrophy (DMD), a debilitating and fatal neuromuscular disorder characterized by progressive muscle wasting and weakness. Mitochondria are a source of cellular ATP involved in Ca2+ regulation and apoptotic signaling. Ameliorating aberrant mitochondrial function has therapeutic potential for reducing DMD disease severity. The dystrophic mdx mouse exhibits peak muscle damage at 21–28 days, which stabilizes after 8 wk. The amino acid taurine is implicated in mitochondrial health and function, with endogenous concentrations low when measured during the cycle of peak muscle damage in mdx mice. Using whole soleus and extensor digitorum longus (EDL) muscle homogenates from 28- and 70-day mdx mice, we found that there was no change in native state mitochondrial complexes using blue native-PAGE. NADH:ubiquinone oxidotreductase subunit-A9 (NDUFA9) protein abundance was lower in soleus muscle of 28- and 70-day mdx mice and EDL muscle of 70-day mdx mice compared with same muscles in WT (C57/BL10ScSn) animals. There were age-dependent increases in both NDUFA9 protein abundance and citrate synthase activity in soleus muscles of mdx and wild-type mice. There was no change in abundances of mitochondrial dynamics proteins mitofusin 2 (Mfn2) and mitochondrial dynamics protein 49 (MiD49). Taurine administration essentially did not affect any measurements of mitochondria. Collectively, these findings suggest mitochondrial content and dynamics are not reduced in the mdx mouse regardless of disease severity. We also elucidate that taurine affords no significant benefit to mitochondrial content or dynamics in the mdx mouse at either 28 or 70 days.

Myofiber / pro-inflammatory macrophage interplay controls muscle damage in mdx mice

2020 ◽  
Author(s):  
Marielle Saclier ◽  
Sabrina Ben Larbi ◽  
Eugénie Moulin ◽  
Rémi Mounier ◽  
Bénédicte Chazaud ◽  
...  
Keyword(s):  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Muscle Disease ◽  
Mdx Mouse ◽  
Mdx Mice ◽  
Dystrophic Muscle ◽  
Cellular Events ◽  
Inflammatory Status ◽  
Inflammatory Phenotype ◽  
Inflammatory Macrophages

SummaryDuchenne Muscular Dystrophy is a genetic muscle disease characterized by chronic inflammation and fibrosis, which is mediated by a pro-fibrotic macrophage population expressing pro-inflammatory markers. The aim of this study was to characterize cellular events leading to the alteration of macrophage properties, and to modulate macrophage inflammatory status using the gaseous mediator H2S. We first analyzed the relationship between myofibers and macrophages in the mdx mouse model of Duchenne Muscular Dystrophy using coculture experiments. We showed that normal myofibers derived from mdx mice strongly skewed the polarization of resting macrophages towards a pro-inflammatory phenotype. Treatment of mdx mice with NaHS, an H2S donor, reduced the number of pro-inflammatory macrophages in skeletal muscle, which was associated with a decrease in the number of nuclei per fiber, a reduction of myofiber branching and a reduced fibrosis. These results identify an interplay between myofibers and macrophages where dystrophic myofibers contribute to the maintenance of a highly inflammatory environment that skews the macrophage status, which in turn favors myofiber damage, myofiber branching and fibrosis establishment. They also identify H2S donors as a potential therapeutic strategy to improve dystrophic muscle phenotype by modulating macrophage inflammatory status.

scholarly journals Metabolomic Analyses Reveal Extensive Progenitor Cell Deficiencies in a Mouse Model of Duchenne Muscular Dystrophy

Metabolites ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 61 ◽  
Author(s):  
Josiane Joseph ◽  
Dong Cho ◽  
Jason Doles
Keyword(s):  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Mouse Model ◽  
Progenitor Cell ◽  
Treatment Options ◽  
Cell Types ◽  
Mdx Mouse ◽  
Mdx Mice ◽  
Metabolic Alterations ◽  
Potential Contributor

Duchenne muscular dystrophy (DMD) is a musculoskeletal disorder that causes severe morbidity and reduced lifespan. Individuals with DMD have an X-linked mutation that impairs their ability to produce functional dystrophin protein in muscle. No cure exists for this disease and the few therapies that are available do not dramatically delay disease progression. Thus, there is a need to better understand the mechanisms underlying DMD which may ultimately lead to improved treatment options. The muscular dystrophy (MDX) mouse model is frequently used to explore DMD disease traits. Though some studies of metabolism in dystrophic mice exist, few have characterized metabolic profiles of supporting cells in the diseased environment. Using nontargeted metabolomics we characterized metabolic alterations in muscle satellite cells (SCs) and serum of MDX mice. Additionally, live-cell imaging revealed MDX-derived adipose progenitor cell (APC) defects. Finally, metabolomic studies revealed a striking elevation of acylcarnitines in MDX APCs, which we show can inhibit APC proliferation. Together, these studies highlight widespread metabolic alterations in multiple progenitor cell types and serum from MDX mice and implicate dystrophy-associated metabolite imbalances in APCs as a potential contributor to adipose tissue disequilibrium in DMD.

Talin, vinculin and DRP (utrophin) concentrations are increased at mdx myotendinous junctions following onset of necrosis

1994 ◽  
Vol 107 (6) ◽  
pp. 1477-1483 ◽  
Author(s):  
D.J. Law ◽  
D.L. Allen ◽  
J.G. Tidball
Keyword(s):  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Cytoskeletal Proteins ◽  
Mdx Mouse ◽  
Mdx Mice ◽  
Myotendinous Junction ◽  
Glycoprotein Complex ◽  
Transmembrane Glycoprotein ◽  
Muscle Necrosis ◽  
Myotendinous Junctions

Duchenne muscular dystrophy (DMD) and the myopathy seen in the mdx mouse both result from absence of the protein dystrophin. Structural similarities between dystrophin and other cytoskeletal proteins, its enrichment at myotendinous junctions, and its indirect association with laminin mediated by a transmembrane glycoprotein complex suggest that one of dystrophin's functions in normal muscle is to form one of the links between the actin cytoskeleton and the extracellular matrix. Unlike Duchenne muscular dystrophy patients, mdx mice suffer only transient muscle necrosis, and are able to regenerate damaged muscle tissue. The present study tests the hypothesis that mdx mice partially compensate for dystrophin's absence by upregulating one or more dystrophin-independent mechanisms of cytoskeleton-membrane association. Quantitative analysis of immunoblots of adult mdx muscle samples showed an increase of approximately 200% for vinculin and talin, cytoskeletal proteins that mediate thin filament-membrane interactions at myotendinous junctions. Blots also showed an increase (143%) in the dystrophin-related protein called utrophin, another myotendinous junction constituent, which may be able to substitute for dystrophin directly. Muscle samples from 2-week-old animals, a period immediately preceding the onset of muscle necrosis, showed no significant differences in protein concentration between mdx and controls. Quantitative analyses of confocal images of myotendinous junctions from mdx and control muscles show significantly higher concentrations of talin and vinculin at the myotendinous junctions of mdx muscle. These findings indicate that mdx mice may compensate in part for the absence of dystrophin by increased expression of other molecules that subsume dystrophin's mechanical function.

EPA protects against muscle damage in the mdx mouse model of Duchenne muscular dystrophy by promoting a shift from the M1 to M2 macrophage phenotype

2013 ◽  
Vol 264 (1-2) ◽  
pp. 41-47 ◽  
Author(s):  
Samara Camaçari de Carvalho ◽  
Leticia Montanholi Apolinário ◽  
Selma Maria Michelin Matheus ◽  
Humberto Santo Neto ◽  
Maria Julia Marques
Keyword(s):  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Mouse Model ◽  
Muscle Damage ◽  
Mdx Mouse ◽  
M2 Macrophage ◽  
Macrophage Phenotype

scholarly journals Soluble guanylate cyclase stimulation mitigates skeletal and cardiac muscle dysfunction in a mdx model of Duchenne muscular dystrophy

2021 ◽  
Author(s):  
Ling Zhang ◽  
Yuanyuan Xu ◽  
Keyvan Yousefi ◽  
Camila I. Irion ◽  
Roger A. Alvarez ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Guanylate Cyclase ◽  
Soluble Guanylate Cyclase ◽  
Signal Propagation ◽  
Guanosine Monophosphate ◽  
Muscle Pathology ◽  
Mdx Mice

AbstractThe impairment of neuronal nitric oxide synthase (nNOS) signaling contributes to disease pathology in the muscle wasting disorder Duchenne muscular dystrophy (DMD). nNOS signal propagation occurs through nitric oxide sensitive soluble guanylate cyclase (sGC), a critical source of cyclic guanosine monophosphate (cGMP) in muscle. Although both nNOS and sGC activity are impaired in DMD patients, little is known about sGC as a therapeutic target. In this study, we tested the hypothesis that stimulating sGC activity with the allosteric agonist BAY41-8543 mitigates striated muscle pathology in the mdx4cv mouse model of DMD. In contrast to DMD patients, mdx mice exhibited greater basal sGC activity than wild type controls with preservation of cGMP levels due partly to upregulation of sGC in some muscles. Stimulating sGC activity in mdx mice with BAY41-8543 substantially reduced skeletal muscle damage, macrophage densities and inflammation and significantly increased resistance to contraction-induced fatigue. BAY41-8543 also enhanced in vivo diaphragm function while reducing breathing irregularities suggesting improved respiratory function. BAY41-8543 attenuated cardiac hypertrophic remodeling, fibrosis and diastolic dysfunction including left atrium enlargement in aged mdx mice. Overall, sGC stimulation significantly mitigated skeletal and cardio-respiratory dysfunction in mdx4cv mice. Importantly, this study provides compelling pre-clinical evidence supporting sGC as a novel target in DMD and the repurposing of FDA-approved sGC stimulators, such as riociguat and veraciguat, as a novel therapeutic approach for DMD.

scholarly journals Ultrasonography validation for early alteration of diaphragm echodensity and function in the mdx mouse model of Duchenne muscular dystrophy

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245397
Author(s):  
Antonietta Mele ◽  
Paola Mantuano ◽  
Adriano Fonzino ◽  
Francesco Rana ◽  
Roberta Francesca Capogrosso ◽  
...  
Keyword(s):  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Mouse Model ◽  
Ex Vivo ◽  
Eccentric Contraction ◽  
Invasive Technique ◽  
Mdx Mouse ◽  
Early Stages ◽  
Over Time

The mdx mouse model of Duchenne muscular dystrophy is characterized by functional and structural alterations of the diaphragm since early stages of pathology, closely resembling patients’ condition. In recent years, ultrasonography has been proposed as a useful longitudinal non-invasive technique to assess mdx diaphragm dysfunction and evaluate drug efficacy over time. To date, only a few preclinical studies have been conducted. Therefore, an independent validation of this method by different laboratories is needed to increase results reliability and reduce biases. Here, we performed diaphragm ultrasonography in 3- and 6-month-old mdx mice, the preferred age-window for pharmacology studies. The alteration of diaphragm function over time was measured as diaphragm ultrasound movement amplitude. At the same time points, a first-time assessment of diaphragm echodensity was performed, as an experimental index of progressive loss of contractile tissue. A parallel evaluation of other in vivo and ex vivo dystrophy-relevant readouts was carried out. Both 3- and 6-month-old mdx mice showed a significant decrease in diaphragm amplitude compared to wild type (wt) mice. This index was well-correlated either with in vivo running performance or ex vivo isometric tetanic force of isolated diaphragm. In addition, diaphragms from 6-month-old dystrophic mice were also highly susceptible to eccentric contraction ex vivo. Importantly, we disclosed an age-dependent increase in echodensity in mdx mice not observed in wt animals, which was independent from abdominal wall thickness. This was accompanied by a notable increase of pro-fibrotic TGF-β1 levels in the mdx diaphragm and of non-muscle tissue amount in diaphragm sections stained by hematoxylin & eosin. Our findings corroborate the usefulness of diaphragm ultrasonography in preclinical drug studies as a powerful tool to monitor mdx pathology progression since early stages.

scholarly journals BETs inhibition attenuates oxidative stress and preserves muscle integrity in Duchenne muscular dystrophy

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Marco Segatto ◽  
Roberta Szokoll ◽  
Raffaella Fittipaldi ◽  
Cinzia Bottino ◽  
Lorenzo Nevi ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Skeletal Muscle ◽  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Mdx Mouse ◽  
Early Event ◽  
Dystrophic Muscle ◽  
Protein Levels ◽  
Bet Inhibitors ◽  
Ros Metabolism

AbstractDuchenne muscular dystrophy (DMD) affects 1 in 3500 live male births. To date, there is no effective cure for DMD, and the identification of novel molecular targets involved in disease progression is important to design more effective treatments and therapies to alleviate DMD symptoms. Here, we show that protein levels of the Bromodomain and extra-terminal domain (BET) protein BRD4 are significantly increased in the muscle of the mouse model of DMD, the mdx mouse, and that pharmacological inhibition of the BET proteins has a beneficial outcome, tempering oxidative stress and muscle damage. Alterations in reactive oxygen species (ROS) metabolism are an early event in DMD onset and they are tightly linked to inflammation, fibrosis, and necrosis in skeletal muscle. By restoring ROS metabolism, BET inhibition ameliorates these hallmarks of the dystrophic muscle, translating to a beneficial effect on muscle function. BRD4 direct association to chromatin regulatory regions of the NADPH oxidase subunits increases in the mdx muscle and JQ1 administration reduces BRD4 and BRD2 recruitment at these regions. JQ1 treatment reduces NADPH subunit transcript levels in mdx muscles, isolated myofibers and DMD immortalized myoblasts. Our data highlight novel functions of the BET proteins in dystrophic skeletal muscle and suggest that BET inhibitors may ameliorate the pathophysiology of DMD.

MDX mouse myopathy I: Presence or absence of sarcolemmal lesions in tibialis anterior muscles from mice of different ages

1989 ◽  
Vol 47 ◽  
pp. 1070-1071
Author(s):  
H.D. Geissinger ◽  
L.D. Rhodes
Keyword(s):  
Animal Model ◽  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Tibialis Anterior ◽  
Extensor Digitorum Longus ◽  
Morphological Analysis ◽  
Control Mouse ◽  
Mdx Mouse ◽  
Mdx Mice ◽  
Recent Interest

Since the ‘mdx’ mouse appears to have the same basic defect as sufferers of human Duchenne Muscular Dystrophy (DMD), much recent interest in this possible animal model for the human disease has been generated. Perforations in the sarcolemma have been reported recently in the necrotic tibialis anterior (TA) of 35-days-old and the extensor digitorum longus muscles of 39-days-old ‘mdx’ mice. It is the purpose of this communication to find out if these lesions occur not only in necrotic, but also in unaffected, or in centronucleated fibers of the TA of mice which are younger than 35, or older than 39 days.METHODS: TA from 22-, 25-, 41-, 61- and 99-days-old C57BL/10ScSn/MDX and C57BL/lOScSn control mice were pinned on corkboard in a relaxed state, prefixed for 30 minutes in 2.5% glutaraldehyde followed by routine processing for TEM. Appropriate micrographs were evaluated for a more detailed morphological analysis of the sarcolemma (SL) and the basal lamina (BL).RESULTS: It should be stated beforehand that in all muscles examined the BL appeared to be intact. In the muscles of a 25-days-old control mouse the SL appeared quite intact (FIG. 1). In contrast to this small perforations or large tears in the SL could be seen in otherwise unaffected muscles of 22- (FIG. 2), 25- and 41-days-old ‘mdx’ mice, as well as in necrotic and regenerating fibers of mice from these ages.

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