Nutraceutical and pharmaceutical cocktails did not preserve diaphragm muscle function or reduce muscle damage in D2‐mdx mice

Abstract

Duchenne muscular dystrophy is characterized by the absence of dystrophin protein and causes muscle weakness and muscle injury, culminating in respiratory failure and cardiomyopathy.Quercetin transiently improved respiratory function but failed to maintain long-term therapeutic benefits in mdx mice. In this study, we combined quercetin with nicotinamide riboside (NR), lisinopril and prednisolone to assess the efficacy of quercetin-based cocktails. We hypothesized that quercetin, NR and lisinopril independently would improve respiratory function and decrease diaphragmatic injury and when combined would have additive effects. To address this hypothesis, in vivo respiratory function, in vitro diaphragmatic function and histological injury were assessed in DBA (healthy), D2-mdx (dystrophic) and D2-mdx mice treated with combinations of quercetin, NR and lisinopril from 4 to 11 months of age. Respiratory function, assessed using whole-body plethysmography, was largely similar between healthy and dystrophin-deficient mice. Diaphragm specific tension was decreased by ∼50% in dystrophic mice compared with healthy mice (P < 0.05), but fatigue resistance was similar between groups. Contractile area was decreased by ∼10% (P < 0.05) and fibrotic area increased from 3.5% in healthy diaphragms to 27% (P < 0.05) in dystrophic diaphragms. Contrary to expectations, these functional and histological parameters of disease were not offset by any intervention. These data suggest that quercetin, NR and lisinopril, independently and in combination, did not prevent diaphragmatic injury or preserve respiratory function. K E Y W O R D SACE inhibitor, duchenne muscular dystrophy, glucocorticoid, prednisolone, quercetin 1 Experimental Physiology. 2020;105:989-999.wileyonlinelibrary.com/journal/eph 989

Indices of Defective Autophagy in Whole Muscle and Lysosome Enriched Fractions From Aged D2-mdx Mice

“…Specifically, we discovered that in 11 months old D2-mdx mice fibrosis was increased by approximately 5-fold compared to healthy controls. Further, we also discovered specific tension was decreased by approximately 50% compared to healthy controls (Spaulding et al, 2020b). Similarly, in limb muscles from these D2-mdx, tetanic force and specific tension in soleus were both decreased by 30% and in EDL were decreased by 50 and 20%, respectively, compared to DBA.…”

“…In the diaphragm, increased LC3A/B II along with increased p62 is consistent with impaired degradation of autophagosomes, while in the gastrocnemius similar LC3A/B II and decreased p62 is supportive of increased degradation of autophagosomes (Ichimura and Komatsu, 2010). Maintenance of autophagosome degradation in limb muscle is associated with attenuated functional decline in limb muscles (soleus and EDL) compared to diaphragms all from these animals (Spaulding et al, 2019b(Spaulding et al, , 2020b. The mechanism underlying this fundamental difference is beyond the scope of this investigation, though speculatively may be influenced by the different activation patterns of these muscles, exposure to different forces, their differing fiber types, and/or differing metabolic profiles (Silverman and Atwood, 1980;Parry and Parslow, 1981;Petrof et al, 1993a;Zardini and Parry, 1994;Augusto et al, 2004), compounded by different rates of disease progression (Hammers et al, 2020).…”

“…Animals were fed ad libitum. Functional and histological data from the diaphragm and limb muscles from these mice has been previously published (Spaulding et al, 2019b(Spaulding et al, , 2020b. Briefly, 11 month old male D2.B10-Dmdmdx/J (D2-mdx; dystrophin-deficient) and male DBA-2J (DBA; healthy control) mice were sedated to a surgical level of anesthesia, the gastrocnemius muscles and diaphragms removed, and mice were euthanized via exsanguination.…”

GSK3 inhibition improves skeletal muscle function and whole-body metabolism in the severe DBA/2Jmdxmouse model

“…In 2016, Coley and colleagues 16 reported a worsened dystrophic phenotype in mdx mice that were backcrossed onto a DBA/2J (D2) strain compared with the C57 strain. With early onset muscle pathology and weakness [16][17][18] , the D2 mdx mouse has emerged as a viable preclinical model for DMD [17][18][19][20][21][22] . In this study, we first compared GSK3β content and activation status (Ser9 phosphorylation) in muscles from age-matched C57 and D2 mdx mice.…”

Análise histológica e molecular do músculo diafragma após tratamento com diferentes glicocorticoides e sob a associação do ácido graxo ômega 3 e dexametasona em ratos

“…Embora escassas, as primeiras pesquisas sobre a ação de glicocorticoides no músculo diafragma datam de 1950 e vêm aumentando com o passar dos anos (Leupin, 1950;Wool, 1960;Veldsema-Currie et al, 1976;Drakontides, 1982;Wilcox et al, 1989;Viires et al, 1990;Petrof et al, 1995;Jiang et al, 1996;Nava et al, 1996;Fletcher et al, 2000;Eason et al, 2003;Mahzabin et al, 2017;Mauricio et al, 2017;Spaulding et al, 2020), porém, não compatível com sua importância clínica, uma vez que muitos pacientes em terapia com glicocorticoides são portadores de doenças neuromusculares degenerativas, indo a óbito, principalmente por falência do sistema respiratório (Engel AG, 1994). Figura 5.…”