Effects of PDE5 inhibition on dystrophic muscle following an acute bout of downhill running and endurance training

Lack of sarcolemma-localized neuronal nitric oxide synthase mu (nNOSμ) contributes to muscle damage and fatigue in dystrophic muscle. In this study, we examined the effects of compensating for lack of nNOSμ with a phosphodiesterase type 5 (PDE5) inhibitor in mdx mice following downhill running and endurance training. Dystrophic mice ( mdx) were treated with sildenafil citrate and compared with untreated mdx and wild-type mice after an acute bout of downhill running and during a progressive low-intensity treadmill running program (5 days/wk, 4 wk). Magnetic resonance imaging (MRI) and spectroscopy (MRS) transverse relaxation time constant (T2) of hindlimb and forelimb muscles were measured as a marker of muscle damage after downhill running and throughout training. The MRI blood oxygenation level dependence (BOLD) response and 31phosphorus MRS (31P-MRS) data were acquired after stimulated muscle contractions. After downhill running, the increase in T2 was attenuated ( P < 0.05) in treated mdx and wild-type mice compared with untreated mdx. During training, resting T2 values did not change in wild-type and mdx mice from baseline values; however, the running distance completed during training was greater ( P < 0.05) in treated mdx (>90% of target distance) and wild-type (100%) than untreated mdx (60%). The post-contractile BOLD response was greater ( P < 0.05) in treated mdx that trained than untreated mdx, with no differences in muscle oxidative capacity, as measured by 31P-MRS. Our findings indicate that PDE5 inhibition reduces muscle damage after a single bout of downhill running and improves performance during endurance training in dystrophic mice, possibly because of enhanced microvascular function. NEW & NOTEWORTHY This study examined the combined effects of PDE5 inhibition and exercise in dystrophic muscle using high-resolution magnetic resonance imaging and spectroscopy. Our findings demonstrated that sildenafil citrate reduces muscle damage after a single bout of downhill running, improves endurance-training performance, and enhances microvascular function in dystrophic muscle. Collectively, the results support the combination of exercise and PDE5 inhibition as a therapeutic approach in muscular dystrophies lacking nNOSμ.

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SERCA1 overexpression minimizes skeletal muscle damage in dystrophic mouse models

AJP Cell Physiology ◽

10.1152/ajpcell.00341.2014 ◽

2015 ◽

Vol 308 (9) ◽

pp. C699-C709 ◽

Cited By ~ 23

Author(s):

Davi A. G. Mázala ◽

Stephen J. P. Pratt ◽

Dapeng Chen ◽

Jeffery D. Molkentin ◽

Richard M. Lovering ◽

...

Keyword(s):

Mouse Model ◽

Muscle Damage ◽

Muscle Wasting ◽

Mdx Mice ◽

Functional Impairments ◽

Wild Type ◽

Skeletal Muscle Damage ◽

Threefold Increase ◽

Intracellular Ca ◽

Cellular Markers

Duchenne muscular dystrophy (DMD) is characterized by progressive muscle wasting secondary to repeated muscle damage and inadequate repair. Elevations in intracellular free Ca2+ have been implicated in disease progression, and sarcoplasmic/endoplasmic reticulum Ca2+-ATPase 1 (SERCA1) overexpression has been shown to ameliorate the dystrophic phenotype in mdx mice. The purpose of this study was to assess the effects of SERCA1 overexpression in the more severe mdx/Utr−/− mouse model of DMD. Mice overexpressing SERCA1 were crossed with mdx/Utr+/− mice to generate mdx/Utr−/−/+SERCA1 mice and compared with wild-type (WT), WT/+SERCA1, mdx/+SERCA1, and genotype controls. Mice were assessed at ∼12 wk of age for changes in Ca2+ handling, muscle mass, quadriceps torque, markers of muscle damage, and response to repeated eccentric contractions. SERCA1-overexpressing mice had a two- to threefold increase in maximal sarcoplasmic reticulum Ca2+-ATPase activity compared with WT which was associated with normalization in body mass for both mdx/+SERCA1 and mdx/Utr−/−/+SERCA1. Torque deficit in the quadriceps after eccentric injury was 2.7-fold greater in mdx/Utr−/− vs. WT mice, but only 1.5-fold greater in mdx/Utr−/−/+SERCA1 vs. WT mice, an attenuation of 44%. Markers of muscle damage (% centrally nucleated fibers, necrotic area, and serum creatine kinase levels) were higher in both mdx and mdx/Utr−/− vs. WT, and all were attenuated by overexpression of SERCA1. These data indicate that SERCA1 overexpression ameliorates functional impairments and cellular markers of damage in a more severe mouse model of DMD. These findings support targeting intracellular Ca2+ control as a therapeutic approach for DMD.

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

Journal of Applied Physiology ◽

10.1152/japplphysiol.00776.2015 ◽

2017 ◽

Vol 122 (4) ◽

pp. 828-843 ◽

Cited By ~ 18

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.

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Pharmacological activation of SERCA ameliorates dystrophic phenotypes in dystrophin-deficient mdx mice

Human Molecular Genetics ◽

10.1093/hmg/ddab100 ◽

2021 ◽

Author(s):

Ken’ichiro Nogami ◽

Yusuke Maruyama ◽

Fusako Sakai-Takemura ◽

Norio Motohashi ◽

Ahmed Elhussieny ◽

...

Keyword(s):

Muscular Strength ◽

Therapeutic Strategy ◽

Genetic Disorder ◽

Mdx Mice ◽

Proof Of Concept ◽

Wild Type ◽

Dystrophic Muscle ◽

Muscular Dysfunction ◽

Exercise Induced ◽

Muscular Damage

Abstract Duchenne muscular dystrophy (DMD) is an X-linked genetic disorder characterized by progressive muscular weakness due to the loss of dystrophin. Extracellular Ca2+ flows into the cytoplasm through membrane tears in dystrophin-deficient myofibers, which leads to muscle contracture and necrosis. Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) takes up cytosolic Ca2+ into the sarcoplasmic reticulum (SR), but its activity is decreased in dystrophic muscle. Here, we show that an allosteric SERCA activator, CDN1163, ameliorates dystrophic phenotypes in dystrophin-deficient mdx mice. Administration of CDN1163 prevented exercise-induced muscular damage and restored mitochondrial function. In addition, treatment with CDN1163 for seven weeks enhanced muscular strength and reduced muscular degeneration and fibrosis in mdx mice. Our findings provide preclinical proof-of-concept evidence that pharmacological activation of SERCA could be a promising therapeutic strategy for DMD. Moreover, CDN1163 improved muscular strength surprisingly in wild-type mice, which may pave the new way for the treatment of muscular dysfunction.

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North American ginseng protects against muscle damage and reduces neutrophil infiltration after an acute bout of downhill running in rats

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2014-0331 ◽

2015 ◽

Vol 40 (2) ◽

pp. 116-121 ◽

Cited By ~ 4

Author(s):

Mehrbod Estaki ◽

Earl G. Noble

Keyword(s):

Muscle Damage ◽

Eccentric Exercise ◽

North American ◽

Neutrophil Infiltration ◽

American Ginseng ◽

Functional Deficits ◽

Downhill Running ◽

Single Bout ◽

Male Wistar Rats ◽

Exercise Induced

Eccentric muscle contractions such as those experienced during downhill running are associated with inflammation, delayed-onset of muscle soreness, myofiber damage, and various functional deficits. North American ginseng (Panax quinquefolius L.) has been reported to possess anti-inflammatory properties and thus may offset some of this exercise-induced damage. Hence, we tested the hypothesis that intervention with North American ginseng would reduce eccentric exercise-induced muscle damage and inflammation. Male Wistar rats were fed (300 mg/(kg·day)–1) of either an alcohol (AL) or aqueous (AQ) extract of North American ginseng for 14 days before a single bout of downhill running and were compared with matching nonexercised (C) groups. Plasma creatine kinase levels were significantly reduced in both ginseng treated groups compared with the C group that received a water placebo (p < 0.002). Further, the AQ but not AL group also showed attenuated morphological signs of damage (hemotoxylin and eosin) as well as reduced levels of infiltrating neutrophils (HIS48) in the soleus muscle (p < 0.001). In summary, supplementation with an AQ but not AL extract of North American ginseng was able to reduce eccentric exercise-induced muscle damage and inflammation.

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Age-Dependent Dysregulation of Muscle Vasculature and Blood Flow Recovery after Hindlimb Ischemia in the mdx Model of Duchenne Muscular Dystrophy

Biomedicines ◽

10.3390/biomedicines9050481 ◽

2021 ◽

Vol 9 (5) ◽

pp. 481

Author(s):

Paulina Podkalicka ◽

Olga Mucha ◽

Katarzyna Kaziród ◽

Iwona Bronisz-Budzyńska ◽

Sophie Ostrowska-Paton ◽

...

Keyword(s):

Blood Flow ◽

Duchenne Muscular Dystrophy ◽

Muscular Dystrophy ◽

Blood Vessels ◽

Mdx Mice ◽

Hindlimb Ischemia ◽

Double Positive ◽

Functional Studies ◽

Age Dependent ◽

Dystrophic Mice

Duchenne muscular dystrophy (DMD), caused by a lack of functional dystrophin, is characterized by progressive muscle degeneration. Interestingly, dystrophin is also expressed in endothelial cells (ECs), and insufficient angiogenesis has already been hypothesized to contribute to DMD pathology, however, its status in mdx mice, a model of DMD, is still not fully clear. Our study aimed to reveal angiogenesis-related alterations in skeletal muscles of mdx mice compared to wild-type (WT) counterparts. By investigating 6- and 12-week-old mice, we sought to verify if those changes are age-dependent. We utilized a broad spectrum of methods ranging from gene expression analysis, flow cytometry, and immunofluorescence imaging to determine the level of angiogenic markers and to assess muscle blood vessel abundance. Finally, we implemented the hindlimb ischemia (HLI) model, more biologically relevant in the context of functional studies evaluating angiogenesis/arteriogenesis processes. We demonstrated that both 6- and 12-week-old dystrophic mice exhibited dysregulation of several angiogenic factors, including decreased vascular endothelial growth factor A (VEGF) in different muscle types. Nonetheless, in younger, 6-week-old mdx animals, neither the abundance of CD31+α-SMA+ double-positive blood vessels nor basal blood flow and its restoration after HLI was affected. In 12-week-old mdx mice, although a higher number of CD31+α-SMA+ double-positive blood vessels and an increased percentage of skeletal muscle ECs were found, the abundance of pericytes was diminished, and blood flow was reduced. Moreover, impeded perfusion recovery after HLI associated with a blunted inflammatory and regenerative response was evident in 12-week-old dystrophic mice. Hence, our results reinforce the hypothesis of age-dependent angiogenic dysfunction in dystrophic mice. In conclusion, we suggest that older mdx mice constitute an appropriate model for preclinical studies evaluating the effectiveness of vascular-based therapies aimed at the restoration of functional angiogenesis to mitigate DMD severity.

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Twenty-one days of low-intensity eccentric training improve morphological characteristics and function of soleus muscles of mdx mice

Scientific Reports ◽

10.1038/s41598-020-79168-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Paulo S. Pedrazzani ◽

Tatiana O. P. Araújo ◽

Emilly Sigoli ◽

Isabella R. da Silva ◽

Daiane Leite da Roza ◽

...

Keyword(s):

Soleus Muscle ◽

Morphological Characteristics ◽

Training Group ◽

Mdx Mice ◽

Eccentric Training ◽

Active Force ◽

Wild Type ◽

Low Intensity ◽

Sedentary Group ◽

Group 3

AbstractDuchene muscular dystrophy (DMD) is caused by the absence of the protein dystrophin, which leads to muscle weakness, progressive degeneration, and eventually death due to respiratory failure. Low-intensity eccentric training (LIET) has been used as a rehabilitation method in skeletal muscles after disuse. Recently, LIET has also been used for rehabilitating dystrophic muscles, but its effects are still unclear. The purpose of this study was to investigate the effects of 21 days of LIET in dystrophic soleus muscle. Thirty-six male mdx mice were randomized into six groups (n = 6/each): mdx sedentary group; mdx training group-3 days; mdx training group-21 days; wild-type sedentary group; wild-type training group-3 days and wild-type training group-21 days. After the training sessions, animals were euthanized, and fragments of soleus muscles were removed for immunofluorescence and histological analyses, and measurements of active force and Ca2+ sensitivity of the contractile apparatus. Muscles of the mdx training group-21 days showed an improvement in morphological characteristics and an increase of active force when compared to the sedentary mdx group. The results show that LIET can improve the functionality of dystrophic soleus muscle in mice.

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The effects of a single bout of downhill running and ensuing delayed onset of muscle soreness on running economy performed 48 h later

European Journal of Applied Physiology ◽

10.1007/s00421-003-0857-8 ◽

2003 ◽

Vol 90 (1-2) ◽

pp. 29-34 ◽

Cited By ~ 92

Author(s):

William A. Braun ◽

Darren J. Dutto

Keyword(s):

Muscle Soreness ◽

Running Economy ◽

Delayed Onset ◽

Downhill Running ◽

Single Bout

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Treatment with rGDF11 does not improve the dystrophic muscle pathology of mdx mice

Skeletal Muscle ◽

10.1186/s13395-016-0092-8 ◽

2016 ◽

Vol 6 (1) ◽

Cited By ~ 11

Author(s):

Fabrizio Rinaldi ◽

Yu Zhang ◽

Ricardo Mondragon-Gonzalez ◽

Jeffrey Harvey ◽

Rita C. R. Perlingeiro

Keyword(s):

Muscle Pathology ◽

Mdx Mice ◽

Dystrophic Muscle

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Early metabolic changes measured by 1H MRS in healthy and dystrophic muscle after injury

Journal of Applied Physiology ◽

10.1152/japplphysiol.00530.2012 ◽

2012 ◽

Vol 113 (5) ◽

pp. 808-816 ◽

Cited By ~ 14

Author(s):

Su Xu ◽

Stephen J. P. Pratt ◽

Espen E. Spangenburg ◽

Richard M. Lovering

Keyword(s):

Skeletal Muscle ◽

Muscle Injury ◽

Tibialis Anterior Muscle ◽

Metabolic Changes ◽

Mdx Mice ◽

Resonance Spectroscopy ◽

Dystrophic Muscle ◽

1H Mrs ◽

Skeletal Muscle Injury

Skeletal muscle injury is often assessed by clinical findings (history, pain, tenderness, strength loss), by imaging, or by invasive techniques. The purpose of this work was to determine if in vivo proton magnetic resonance spectroscopy (1H MRS) could reveal metabolic changes in murine skeletal muscle after contraction-induced injury. We compared findings in the tibialis anterior muscle from both healthy wild-type (WT) muscles (C57BL/10 mice) and dystrophic ( mdx mice) muscles (an animal model for human Duchenne muscular dystrophy) before and after contraction-induced injury. A mild in vivo eccentric injury protocol was used due to the high susceptibility of mdx muscles to injury. As expected, mdx mice sustained a greater loss of force (81%) after injury compared with WT (42%). In the uninjured muscles, choline (Cho) levels were 47% lower in the mdx muscles compared with WT muscles. In mdx mice, taurine levels decreased 17%, and Cho levels increased 25% in injured muscles compared with uninjured mdx muscles. Intramyocellular lipids and total muscle lipid levels increased significantly after injury but only in WT. The increase in lipid was confirmed using a permeable lipophilic fluorescence dye. In summary, loss of torque after injury was associated with alterations in muscle metabolite levels that may contribute to the overall injury response in mdx mice. These results show that it is possible to obtain meaningful in vivo 1H MRS regarding skeletal muscle injury.

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