Polygonatum sibiricum polysaccharide ameliorates skeletal muscle aging via mitochondria-associated membrane-mediated calcium homeostasis regulation.

BACKGROUND: Sarcopenia, an age-related disease, is characterized by a gradual loss of muscle mass, strength, and function. It has been linked to abnormal organelle function in myotubes, including the mitochondria and endoplasmic reticulum (ER). Recent studies revealed that mitochondria-associated membranes (MAM), the sites connecting mitochondria and the ER, may be implicated in skeletal muscle aging. In this arena, the potential of Polygonatum sibiricum polysaccharide (PSP) emerges as a beacon of hope. PSP, with its remarkable antioxidant and anti-senescence properties, is on the cusp of a therapeutic revolution, offering a promising strategy to mitigate the impacts of sarcopenia. PURPOSE: The objective of this research is to explore the effects of PSP on age-related muscle dysfunction and the underlying mechanisms involved both in vivo and in vitro. METHODS: In this investigation, we used in vitro experiments using D-galactose (D-gal)-induced aging in C2C12 myotubes and in vivo experiments on aged mice. Key indices were assessed, including reactive oxygen species (ROS) levels, mitochondrial function, the expression of aging-related markers, and the key proteins of mitochondria and MAM fraction. Differentially expressed genes (DEGs) related to mitochondria and ER were identified, and bioinformatic analyses were performed to explore underlying mechanisms. Muscle mass and function were determined to evaluate the quantity and quality of skeletal muscle in vivo. RESULTS: PSP treatment effectively mitigated oxidative stress and mitochondrial malfunction caused by D-gal in C2C12 myotubes, preserving mitochondrial fitness and reducing MAM formation. Besides, PSP attenuated D-gal-induced increases in Ca2+ concentrations intracellularly by modulating the calcium-related proteins, which were also confirmed by gene ontology (GO) analysis of DEGs. In aged mice, PSP increased muscle mass and improved grip strength, hanging time, and other parameters while reducing ROS levels and increasing antioxidant enzyme activities in skeletal muscle tissue. CONCLUSION: PSP offers protection against age-associated muscle impairments. The proposed mechanism suggests that modulation of calcium homeostasis via regulation of the MAM results in a favorable functional outcome during skeletal muscle aging. The results of this study highlight the prospect of PSP as a curative intervention for sarcopenia and affiliated pathological conditions, warranting further investigation.

Lactobacillus gasseri BNR17 Ameliorates Dexamethasone-Induced Muscle Loss in BALB/c Mice and C2C12 Myotubes.

This study aimed to investigate the effects and mechanism of Lactobacillus gasseri BNR17, a probiotic strain isolated from human breast milk, on dexamethasone-induced muscle loss in mice and cultured myotubes. BALB/c mice were intraperitoneally injected with dexamethasone, and orally administered L. gasseri BNR17 for 21 days. L. gasseri BNR17 treatment ameliorated dexamethasone-induced decline in muscle function, as evidenced by an increase in forelimb grip strength, treadmill running time, and rotarod retention time in both female and male mice. In addition, L. gasseri BNR17 treatment significantly increased the mass of the gastrocnemius and quadriceps muscles. Dual-energy X-ray absorptiometry showed a significant increase in lean body mass and a decrease in fat mass in both whole body and hind limb after treatment with L. gasseri BNR17. It was found that L. gasseri BNR17 treatment downregulated serum myostatin level and the protein degradation pathway composed of muscle-specific ubiquitin E3 ligases, MuRF1 and MAFbx, and their transcription factor FoxO3. In contrast, L. gasseri BNR17 treatment upregulated serum insulin-like growth factor-1 level and Akt-mTOR-p70S6K signaling pathway involved in protein synthesis in muscle. As a result, L. gasseri BNR17 treatment significantly increased the levels of major muscular proteins such as myosin heavy chain and myoblast determination protein 1. Consistent with in vivo results, L. gasseri BNR17 culture supernatant significantly ameliorated dexamethasone-induced C2C12 myotube atrophy in vitro. In conclusion, L. gasseri BNR17 ameliorates muscle loss by downregulating the protein degradation pathway and upregulating the protein synthesis pathway.

The Lipophilic Extract from Ginkgo biloba L. Leaves Promotes Glucose Uptake and Alleviates Palmitate-Induced Insulin Resistance in C2C12 Myotubes.

Ginkgo biloba L. (ginkgo) is a widely used medicinal plant around the world. Its leaves, which have been used as a traditional Chinese medicine, are rich in various bioactive components. However, most of the research and applications of ginkgo leaves have focused on terpene trilactones and flavonol glycosides, thereby overlooking the other active components. In this study, a lipophilic extract (GL) was isolated from ginkgo leaves. This extract is abundant in lipids and lipid-like molecules. Then, its effect and potential mechanism on glucose uptake and insulin resistance in C2C12 myotubes were investigated. The results showed that GL significantly enhanced the translocation of GLUT4 to the plasma membrane, which subsequently promoted glucose uptake. Meanwhile, it increased the phosphorylation of AMP-activated protein kinase (AMPK) and its downstream targets. Both knockdown of AMPK with siRNA and inhibition with AMPK inhibitor compound C reversed these effects. Additionally, GL ameliorated palmitate-induced insulin resistance by enhancing insulin-stimulated glucose uptake, increasing the phosphorylation of protein kinase B (PKB/AKT), and restoring the translocation of GLUT4 from the cytoplasm to the membrane. However, pretreatment with compound C abolished these beneficial effects of GL. In conclusion, GL enhances basal glucose uptake in C2C12 myotubes and improves insulin sensitivity in palmitate-induced insulin resistant myotubes through the AMPK pathway.

Identification of Peucedanum japonicum Thunb. extract components and their protective effects against dexamethasone-induced muscle atrophy.

BACKGROUND: Peucedanum japonicum Thunb. (PJ) is a vegetable widely consumed in East Asia and is known to have anticancer and anti-inflammatory effects. However, the effect of PJ on muscle atrophy remains elusive. PURPOSE: This study aimed to investigate the effect of PJ and its active compound on dexamethasone (DEX)-induced muscle atrophy. METHODS: We performed qualitative and quantitative analysis of PJ using ultra-performance liquid chromatography-mass spectrometry tandem mass spectrometry (UPLC-MS/MS) and high-performance liquid chromatography (HPLC), respectively. The efficacy of PJ and its main compound 4-caffeoylquinic acid (CQA) on muscle atrophy was evaluated in DEX-induced myotube atrophy and DEX-induced muscle atrophy in mouse myoblasts (C2C12) and C57BL/6 mice, in vitro and in vivo, respectively. RESULTS: The UPLC-MS/MS and HPLC data showed that the concentration of 4-CQA in PJ was 18.845 mg/g. PJ and 4-CQA treatments significantly inhibited DEX-induced myotube atrophy by decreasing protein synthesis and glucocorticoid translocation to the nucleus in C2C12 myotubes. In addition, PJ enhanced myogenesis by upregulating myogenin and myogenic differentiation 1 in C2C12 cells. PJ supplementation effectively increased muscle function and mass, downregulated atrogenes, and decreased proteasome activity in C57BL/6 mice. Additionally, PJ effectively decreased the nuclear translocation of forkhead transcription factor 3 alpha by inhibiting glucocorticoid receptor. CONCLUSION: Overall, PJ and its active compound 4-CQA alleviated skeletal muscle atrophy by inhibiting protein degradation. Hence, our findings present PJ as a potential novel pharmaceutical candidate for the treatment of muscle atrophy.

Characterization of Skeletal Muscle Regeneration Revealed a Novel Growth Network Induced by Molecular Acupuncture-like Transfection.

The low efficiency of in vivo transfection of a few fibres revealed a novel tissue network that temporally amplified growth stimulation in the entire regenerating rat soleus muscle. This acupuncture-like effect was demonstrated when the fibres began to grow after complete fibre degradation, synchronous inflammation, myoblast and myotube formation. Neonatal sarcoplasmic/endoplasmic reticulum ATPase (SERCA1b) was first detected in this system. The neonatal, fast and slow SERCA isoforms displayed consequent changes with innervation and differentiation, recapitulating events in muscle development. In vivo transfection of myotubes with plasmids expressing dominant negative Ras or a calcineurin inhibitor peptide (Cain/cabin) proved that expression of the slow myosin heavy chain and the slow muscle type SERCA2a are differentially regulated. In vivo transfection of a few nuclei of myotubes with dnRas or SERCA1b shRNA stimulated fibre size growth in the whole regenerating muscle but only until the full size had been reached. Growth stimulation by Ras and SERCA1b antisense was abolished by co-transfection of Cain or with perimuscular injection of IL4 antibody. This revealed a novel signalling network resembling scale-free networks which, starting from transfected fibre myonuclei as "hubs", can amplify growth stimulation uniformly in the entire regenerating muscle.

Cannabidiol protects C2C12 myotubes against cisplatin-induced atrophy by regulating oxidative stress.

Cancer and chemotherapy induce a severe loss of muscle mass (known as cachexia), which negatively impact cancer treatment and patient survival. The aim of the present study was to investigate whether cannabidiol (CBD) administration may potentially antagonize the effects of cisplatin in inducing muscle atrophy, using a model of myotubes in culture. Cisplatin treatment resulted in a reduction of myotube diameter (15.7 ± 0.3 vs. 22.2 ± 0.5 µm, P < 0.01) that was restored to control level with 5 µM CBD (20.1 ± 0.4 µM, P < 0.01). Protein homeostasis was severely altered with a ≈70% reduction in protein synthesis (P < 0.01) and a twofold increase in proteolysis (P < 0.05) in response to cisplatin. Both parameters were dose dependently restored by CBD cotreatment. Cisplatin treatment was associated with increased thiobarbituric acid reactive substances (TBARS) content (0.21 ± 0.03 to 0.48 ± 0.03 nmol/mg prot, P < 0.05), catalase activity (0.24 ± 0.01 vs. 0.13 ± 0.02 nmol/min/µg prot, P < 0.01), whereas CBD cotreatment normalized TBARS content to control values (0.22 ± 0.01 nmol/mg prot, P < 0.01) and reduced catalase activity (0.17 ± 0.01 nmol/min/µg prot, P < 0.05). These changes were associated with increased mRNA expression of GPX1, SOD1, SOD2, and CAT mRNA expression in response to cisplatin (P < 0.01), which was corrected by CBD cotreatment (P < 0.05). Finally, cisplatin treatment increased the mitochondrial protein content of NDUFB8, UQCRC2, COX4, and VDAC1 (involved in mitochondrial respiration and apoptosis), and CBD cotreatment restored their expression to control values. Altogether, our results demonstrated that CBD antagonize the cisplatin-induced C2C12 myotube atrophy and could be used as an adjuvant in the treatment of cancer cachexia to help maintain muscle mass and improve patient quality of life.NEW & NOTEWORTHY In an in vitro model, cisplatin treatment led to myotube atrophy associated with dysregulation of protein homeostasis and increased oxidative stress, resulting in increased apoptosis. Cotreatment with cannabidiol was able to prevent this phenotype by promoting protein homeostasis and reducing oxidative stress.

Camellia oil exhibits anti-fatigue property by modulating antioxidant capacity, muscle fiber, and gut microbial composition in mice.

Camellia seed oil (CO) has high nutritional value and multiple bioactivities. However, the specific anti-fatigue characteristics and the implied mechanism of CO have not yet been fully elucidated. Throughout this investigation, male C57BL/6J mice, aged 8 weeks, underwent exhaustive exercise with or without CO pretreatment (2, 4, and 6 mL/kg BW) for 28 days. CO could extend the rota-rod and running time, reduce blood urea nitrogen levels and serum lactic acid, and increase muscle and hepatic glycogen, adenosine triphosphate, and anti-oxidative indicators. Additionally, CO could upregulate the mRNA and Nrf2 protein expression levels, as well as enhance the levels of its downstream antioxidant enzymes and induce the myofiber-type transformation from fast to slow and attenuate the gut mechanical barrier. Moreover, CO could ameliorate gut dysbiosis by reducing Firmicutes to Bacteroidetes ratio at the phylum level, increasing the percentage of Alistipes, Alloprevotella, Lactobacillus, and Muribaculaceae, and decreasing the proportion of Dubosiella at the genus level. In addition, specific bacterial taxa, which were altered by CO, showed a significant correlation with partial fatigue-related parameters. These findings suggest that CO may alleviate fatigue by regulating antioxidant capacity, muscle fiber transformation, gut mechanical barrier, and gut microbial composition in mice. PRACTICAL APPLICATION: Our study revealed that camellia seed oil (CO) could ameliorate exercise-induced fatigue in mice by modulating antioxidant capacity, muscle fiber, and gut microbial composition in mice. Our results promote the application of CO as an anti-fatigue functional food that targets oxidative stress, myofiber-type transformation, and microbial community.

Ursolic acid alleviates cancer cachexia by inhibiting STAT3 signaling pathways in C2C12 myotube and CT26 tumor-bearing mouse model.

Cancer cachexia, a multi-organ disorder resulting from tumor and immune system interactions, prominently features muscle wasting and affects the survival of patients with cancer. Ursolic acid (UA) is known for its antioxidant, anti-inflammatory, and anticancer properties. However, its impact on cancer cachexia remains unexplored. This study aimed to assess the efficacy of UA in addressing muscle atrophy and organ dysfunction in cancer cachexia and reveal the mechanisms involved. UA dose-dependently ameliorated C2C12 myotube atrophy. Mechanistically, it inhibited the expression of muscle-specific RING finger containing protein 1 (MURF1) and the phosphorylation of signal transducer and activator of transcription 3 (STAT3), and upregulated the mRNA or protein levels of myogenic differentiation antigen and myogenin in cultured C2C12 myotubes treated with conditioned medium. In vivo, UA protected CT26 tumor-bearing mice against loss of body weight, as well as increased skeletal muscle and epididymal fat without affecting tumor growth. Additionally, UA increased food intake in CT26 tumor-bearing mice. The mRNA expression of tumor necrosis-α and interleukin 6 was significantly downregulated in the intestine, gastrocnemius, and heart tissues following 38 d UA administration. UA treatment reversed the levels of myocardial function indicators, including creatine kinase, creatine kinase-MB, lactate dehydrogenase, car-dial troponin T, and glutathione. Finally, UA treatment significantly inhibited the expression of MURF1, the phosphorylation of nuclear factor kappa-B p65, and STAT3 in the gastrocnemius muscle and heart tissues of cachexic mice. Our findings suggest that UA is a promising natural compound for developing dietary supplements for cancer cachexia therapy owing to its anti-catabolic effects.

Therapeutic Effect of an Ursolic Acid-Based Nutraceutical on Neuronal Regeneration after Sciatic Nerve Injury.

Peripheral nerve injuries lead to severe functional impairments and long recovery times, with limited effectiveness and accessibility of current treatments. This has increased interest in natural bioactive compounds, such as ursolic acid (UA). Our study evaluated the effect of an oleolyte rich in UA from white grape pomace (WGPO) on neuronal regeneration in mice with induced sciatic nerve resection, administered concurrently with the induced damage (the WGPO group) and 10 days prior (the PRE-WGPO group). The experiment was monitored at two-time points (4 and 10 days) after injury. After 10 days, the WGPO group demonstrated a reduction in muscle atrophy, evidenced by an increased number and diameter of muscle fibers and a decreased Atrogin-1 and Murf-1 expression relative to the denervated control. It was also observed that 85.7% of neuromuscular junctions (NMJs) were fully innervated, as indicated by the colocalization of α-bungarotoxin and synaptophysin, along with the significant modulation of Oct-6 and S-100. The PRE-WGPO group showed a more beneficial effect on nerve fiber reformation, with a significant increase in myelin protein zero and 95.2% fully innervated NMJs, and a pro-hypertrophic effect in resting non-denervated muscles. Our findings suggest WGPO as a potential treatment for various conditions that require the repair of nerve and muscle injuries.

Dietary short-term supplementation of grape seed proanthocyanidin extract improves pork quality and promotes skeletal muscle fiber type conversion in finishing pigs.

Plant extracts are commonly used as feed additives to improve pork quality. However, due to their high cost, shortening the duration of supplement use can help reduce production costs. In this study, we aimed to investigate the effects of grape seed proanthocyanidin extract (GSPE) on meat quality and muscle fiber characteristics of finishing pigs during the late stage of fattening, which was 30 days in our experimental design. The results indicated that short-term dietary supplementation of GSPE significantly reduced backfat thickness, but increased loin eye area and improved meat color and tenderness. Moreover, GSPE increased slow myosin heavy chain (MyHC) expression and malate dehydrogenase (MDH) activity, while decreasing fast MyHC expression and lactate dehydrogenase (LDH) activity in the Longissimus thoracis (LT) muscle. Additionally, GSPE increased the expression of Sirt1 and PGC-1α proteins in the LT muscle of finishing pigs and upregulated AMP-activated protein kinase α 1 (AMPKα1), AMPKα2, nuclear respiratory factor 1 (NRF1), and calcium/calmodulin-dependent protein kinase kinase ß (CaMKKß) mRNA expression levels. These findings suggest that even during the late stage of fattening, GSPE treatment can regulate skeletal muscle fiber type transformation through the AMPK signaling pathway, thereby affecting the muscle quality of finishing pigs. Therefore, by incorporating GSPE into the diet of pigs during the late stage of fattening, producers can enhance pork quality while reducing production costs.

Steamed Ginseng Berry Powder Ameliorates Skeletal Muscle Atrophy via Myogenic Effects.

Sarcopenia is an age-related loss of muscle mass and function for which there is no approved pharmacological treatment. We tested direct efficacy by evaluating grip strength improvement in a sarcopenia mouse model rather than drug screening, which inhibits specific molecular mechanisms. Various physiological functions of ginseng berries are beneficial to the human body. The present study aimed to evaluate the efficacy and safety of steamed ginseng berry powder (SGBP). SGBP administration increased myotube diameter and suppressed the mRNA expression of sarcopenia-inducing molecules. SGBP also reduced the levels of inflammatory transcription factors and cytokines that are known to induce sarcopenia. Oral administration of SGBP improved muscle mass and physical performance in a mouse model of sarcopenia. In summary, our data suggest that SGBP is a novel therapeutic candidate for the amelioration of muscle weakness, including sarcopenia.

Free radical scavenging polyphenols isolated from Phyllanthus niruri L. ameliorates hyperglycemia via SIRT1 induction and GLUT4 translocation in in vitro and in vivo models.

Type 2 diabetes milletus (T2DM) is a complex multifaceted disorder characterized by insulin resistance in skeletal muscle. Phyllanthus niruri L. is well reported sub-tropical therapeutically beneficial ayurvedic medicinal plant from Euphorbiaceae family used in various body ailments such as metabolic disorder including diabetes. The present study emphasizes on the therapeutic potential of Phyllanthus niruri L. and its phytochemical(s) against insulin resistance conditions and impaired antioxidant activity thereby aiding as an anti-hyperglycemic agent in targeting T2DM. Three compounds were isolated from the most active ethyl acetate fraction namely compound 1 as 1-O-galloyl-6-O-luteoyl-ß-D-glucoside, compound 2 as brevifolincarboxylic acid and compound 3 as ricinoleic acid. Compounds 1 and 2, the two polyphenols enhanced the uptake of glucose and inhibited ROS levels in palmitate induced C2C12 myotubes. PNEAF showed the potent enhancement of glucose uptake in palmitate-induced insulin resistance condition in C2C12 myotubes and significant ROS inhibition was observed in skeletal muscle cell line. PNEAF treated IR C2C12 myotubes and STZ induced Wistar rats elevated SIRT1, PGC1-α signaling cascade through phosphorylation of AMPK and GLUT4 translocation resulting in insulin sensitization. Our study revealed an insight into the efficacy of marker compounds isolated from P. niruri and its enriched ethyl acetate fraction as ROS scavenging agent and helps in attenuating insulin resistance condition in C2C12 myotubes as well as in STZ induced Wistar rat by restoring glucose metabolism. Overall, this study can provide prospects for the marker-assisted development of P. niruri as a phytopharmaceutical drug for the insulin resistance related diabetic complications.

Licochalcone A and B enhance muscle proliferation and differentiation by regulating Myostatin.

BACKGROUND: Myostatin (MSTN) inhibition has demonstrated promise for the treatment of diseases associated with muscle loss. In a previous study, we discovered that Glycyrrhiza uralensis (G. uralensis) crude water extract (CWE) inhibits MSTN expression while promoting myogenesis. Furthermore, three specific compounds of G. uralensis, namely liquiritigenin, tetrahydroxymethoxychalcone, and Licochalcone B (Lic B), were found to promote myoblast proliferation and differentiation, as well as accelerate the regeneration of injured muscle tissue. PURPOSE: The purpose of this study was to build on our previous findings on G. uralensis and demonstrate the potential of its two components, Licochalcone A (Lic A) and Lic B, in muscle mass regulation (by inhibiting MSTN), aging and muscle formation. METHODS: G. uralensis, Lic A, and Lic B were evaluated thoroughly using in silico, in vitro and in vivo approaches. In silico analyses included molecular docking, and dynamics simulations of these compounds with MSTN. Protein-protein docking was carried out for MSTN, as well as for the docked complex of MSTN-Lic with its receptor, activin type IIB receptor (ACVRIIB). Subsequent in vitro studies used C2C12 cell lines and primary mouse muscle stem cells to acess the cell proliferation and differentiation of normal and aged cells, levels of MSTN, Atrogin 1, and MuRF1, and plasma MSTN concentrations, employing techniques such as western blotting, immunohistochemistry, immunocytochemistry, cell proliferation and differentiation assays, and real-time RT-PCR. Furthermore, in vivo experiments using mouse models focused on measuring muscle fiber diameters. RESULTS: CWE of G. uralensis and two of its components, namely Lic A and B, promote myoblast proliferation and differentiation by inhibiting MSTN and reducing Atrogin1 and MuRF1 expressions and MSTN protein concentration in serum. In silico interaction analysis revealed that Lic A (binding energy -6.9 Kcal/mol) and B (binding energy -5.9 Kcal/mol) bind to MSTN and reduce binding between it and ACVRIIB, thereby inhibiting downstream signaling. The experimental analysis, which involved both in vitro and in vivo studies, demonstrated that the levels of MSTN, Atrogin 1, and MuRF1 were decreased when G. uralensis CWE, Lic A, or Lic B were administered into mice or treated in the mouse primary muscle satellite cells (MSCs) and C2C12 myoblasts. The diameters of muscle fibers increased in orally treated mice, and the differentiation and proliferation of C2C12 cells were enhanced. G. uralensis CWE, Lic A, and Lic B also promoted cell proliferation in aged cells, suggesting that they may have anti-muslce aging properties. They also reduced the expression and phosphorylation of SMAD2 and SMAD3 (MSTN downstream effectors), adding to the evidence that MSTN is inhibited. CONCLUSION: These findings suggest that CWE and its active constituents Lic A and Lic B have anti-mauscle aging potential. They also have the potential to be used as natural inhibitors of MSTN and as therapeutic options for disorders associated with muscle atrophy.

Dietary oleic acid intake increases the proportion of type 1 and 2X muscle fibers in mice.

Skeletal muscle is one of the largest metabolic tissues in mammals and is composed of four different types of muscle fibers (types 1, 2A, 2X, and 2B); however, type 2B is absent in humans. Given that slow-twitch fibers are superior to fast-twitch fibers in terms of oxidative metabolism and are rich in mitochondria, shift of muscle fiber types in direction towards slower fiber types improves metabolic disorders and endurance capacity. We previously had reported that oleic acid supplementation increases type 1 fiber formation in C2C12 myotubes; however, its function still remains unclear. This study aimed to determine the effect of oleic acid on the muscle fiber types and endurance capacity. An in vivo mouse model was used, and mice were fed a 10% oleic acid diet for 4 weeks. Two different skeletal muscles, slow soleus muscle with the predominance of slow-twitch fibers and fast extensor digitorum longus (EDL) muscle with the predominance of fast-twitch fibers, were used. We found that dietary oleic acid intake improved running endurance and altered fiber type composition of muscles, the proportion of type 1 and 2X fibers increased in the soleus muscle and type 2X increased in the EDL muscle. The fiber type shift in the EDL muscle was accompanied by an increased muscle TAG content. In addition, blood triacylglycerol (TAG) and non-esterified fatty acid levels decreased during exercise. These changes suggested that lipid utilization as an energy substrate was enhanced by oleic acid. Increased proliferator-activated receptor γ coactivator-1ß protein levels were observed in the EDL muscle, which potentially enhanced the fiber type transitions towards type 2X and muscle TAG content. In conclusion, dietary oleic acid intake improved running endurance with the changes of muscle fiber type shares in mice. This study elucidated a novel functionality of oleic acid in skeletal muscle fiber types. Further studies are required to elucidate the underlying mechanisms. Our findings have the potential to contribute to the field of health and sports science through nutritional approaches, such as the development of supplements aimed at improving muscle function.

Protective Effect of Whole Wheat on Muscle Atrophy in C2C12 Cells via Akt/FoxO1 Signaling Pathways.

Skeletal muscles are important for body movement, postural maintenance, and energy metabolism. Muscle atrophy is caused by various factors, including lack of exercise, age, genetics, and malnutrition, leading to the loss of muscle mass. The Akt/FoxO signaling pathway plays a key role in the regulation of muscle protein synthesis and degradation. Whole wheat contains functional ingredients that may indirectly contribute to muscle health and function and can help prevent or slow the progression of muscle atrophy. In this study, the protective effects of three wheat cultivars (Seodun, Ol, and Shinmichal 1) against hydrogen peroxide-induced muscle atrophy in C2C12 cells were investigated. We found that whole-wheat treatment reduced reactive oxygen species production, prevented glutathione depletion, and increased myotube diameter, thereby reducing muscle atrophy by activating myoblast differentiation. Generally, "Shinmichal 1" exhibited the highest activation of the Akt/FoxO signaling pathway. In contrast, "Seodun" showed similar or slightly higher activities than those of the H2O2-treated only group. In conclusion, whole wheat exerts a protective effect against muscle atrophy by activating the Akt/FoxO signaling pathway. This study indicates that whole wheat may help prevent muscle atrophy.

Advantage of ostarine over raloxifene and their combined treatments for muscle of estrogen-deficient rats.

PURPOSE: Selective androgen (ostarine, OST) and estrogen (raloxifene, RAL) receptor modulators with improved tissue selectivity have been developed as alternatives to hormone replacement therapy. We investigated the combined effects of OST and RAL on muscle tissue in an estrogen-deficient rat model of postmenopausal conditions. METHODS: Three-month-old Sprague Dawley rats were divided into groups: (1) untreated non-ovariectomized rats (Non-OVX), (2) untreated ovariectomized rats (OVX), (3) OVX rats treated with OST, (4) OVX rats treated with RAL, (5) OVX rats treated with OST and RAL. Both compounds were administered in the diet. The average dose received was 0.6 ± 0.1 mg for OST and 11.1 ± 1.2 mg for RAL per kg body weight/day. After thirteen weeks, rat activity, muscle weight, structure, gene expression, and serum markers were analyzed. RESULTS: OST increased muscle weight, capillary ratio, insulin-like growth factor 1 (Igf-1) expression, serum phosphorus, uterine weight. RAL decreased muscle weight, capillary ratio, food intake, serum calcium and increased Igf-1 and Myostatin expression, serum follicle stimulating hormone (FSH). OST + RAL increased muscle nucleus ratio, uterine weight, serum phosphorus, FSH and luteinizing hormone and decreased body and muscle weight, serum calcium. Neither treatment changed muscle fiber size. OVX increased body and muscle weight, decreased uterine weight, serum calcium and magnesium. CONCLUSION: OST had beneficial effects on muscle in OVX rats. Side effects of OST on the uterus and serum electrolytes should be considered before using it for therapeutic purposes. RAL and RAL + OST had less effect on muscle and showed endocrinological side effects on pituitary-gonadal axis.

Jakyak-gamcho-tang, a decoction of Paeoniae Radix and Glycyrrhizae Radix et Rhizoma, ameliorates dexamethasone-induced muscle atrophy and muscle dysfunction.

BACKGROUND: Although chronic treatment with glucocorticoids, such as dexamethasone, is frequently associated with muscle atrophy, effective and safe therapeutics for treating muscle atrophy remain elusive. Jakyak-gamcho-tang (JGT), a decoction of Paeoniae Radix and Glycyrrhizae Radix et Rhizoma, has long been used to relieve muscle tension and control muscle cramp-related pain. However, the effects of JGT on glucocorticoid-induced muscle atrophy are yet to be comprehensively clarified. PURPOSE: The objective of the current study was to validate the protective effect of JGT in dexamethasone-induced muscle atrophy models and elucidate its underlying mechanism through integrated in silico - in vitro - in vivo studies. STUDY DESIGN AND METHODS: Differential gene expression was preliminarily analyzed using the RNA-seq data to determine the effects of JGT on C2C12 myotubes. The protective effects of JGT were further validated in dexamethasone-treated C2C12 myotubes by assessing cell viability, myotube integrity, and mitochondrial function or in C57BL/6 N male mice with dexamethasone-induced muscle atrophy by evaluating muscle mass and physical performance. Transcriptomic pathway analysis was also performed to elucidate the underlying mechanism. RESULTS: Based on preliminary gene set enrichment analysis using the RNA-seq data, JGT regulated various pathways related to muscle differentiation and regeneration. Dexamethasone-treated C2C12 myotubes and muscle tissues of atrophic mice displayed substantial muscle protein degradation and muscle loss, respectively, which was efficiently alleviated by JGT treatment. Importantly, JGT-mediated protective effects were associated with observations such as preservation of mitochondrial function, upregulation of myogenic signaling pathways, including protein kinase B/mammalian target of rapamycin/forkhead box O3, inhibition of ubiquitin-mediated muscle protein breakdown, and downregulation of inflammatory and apoptotic pathways induced by dexamethasone. CONCLUSION: To the best of our knowledge, this is the first report to demonstrate that JGT could be a potential pharmaceutical candidate to prevent muscle atrophy induced by chronic glucocorticoid treatment, highlighting its known effects for relieving muscle spasms and pain. Moreover, transcriptomic pathway analysis can be employed as an efficient in silico tool to predict novel pharmacological candidates and elucidate molecular mechanisms underlying the effects of herbal medications comprising diverse biologically active ingredients.

Effect of ST36 electroacupuncture on the switch of skeletal muscle fibres in mice with sciatic nerve dissociation.

Skeletal muscle is striated muscle that moves autonomously and is innervated by peripheral nerves. Peripheral nerve injury is very common in clinical treatment. However, the commonly used treatment methods often focus on the regeneration of the injured nerve but overlook the pathological changes in the injured skeletal muscle. Acupuncture, as the main treatment for denervated skeletal muscle atrophy, is used extensively in clinical practice. In the present study, a mouse model of lower limb sciatic nerve detachment was constructed and treated with electroacupuncture Stomach 36 to observe the atrophy of lower limb skeletal muscle and changes in skeletal muscle fibre types before and after electroacupuncture Stomach 36 treatment. Mice with skeletal muscle denervation showed a decrease in the proportion of IIa muscle fibres and an increase in the proportion of IIb muscle fibres, after electroacupuncture Stomach 36. The changes were reversed by specific activators of p38 MAPK, which increased IIa myofibre ratio. The results suggest that electroacupuncture Stomach 36 can reverse the change of muscle fibre type from IIb to IIa after denervation of skeletal muscle by inhibiting p38 MAPK. The results provide an important theoretical basis for the treatment of clinical peripheral nerve injury diseases with electroacupuncture, in addition to novel insights that could facilitate the study of pathological changes of denervated skeletal muscle.

Dietary Taurine Supplementation Improves the Meat Quality, Muscle Fiber Type, and Mitochondrial Function of Finishing Pigs.

This study investigated the effects of dietary supplementation with taurine (TAU) on the meat quality, muscle fiber type, and mitochondrial function of finishing pigs. The results demonstrated that TAU significantly increased the a* value while decreasing b*45 min, L*24 h, and drip loss24 h and drip loss48 h in the longissimus dorsi (LD) muscle. Dietary supplemented with TAU reduced the content of lactate and the glycolytic potential (GP) in the LD muscle. Dietary supplemented with TAU enhanced the oxidative fiber-related gene expression as well as increased succinic dehydrogenase and malate dehydrogenase activities while reducing lactate dehydrogenase activity. Furthermore, dietary supplementation with TAU increased the contents of mtDNA and ATP and mitochondrial function-related gene expression. Moreover, TAU enhanced the mRNA expressions of calcineurin (CaN) and nuclear factor of activated T cells c1 (NFATc1) and protein expressions of CNA and NFATc1. The results indicate that dietary TAU supplementation improves meat quality and mitochondrial biogenesis and function and promotes muscle fiber-type conversion from the glycolytic fiber to the oxidative fiber via the CaN/NFATc1 pathway.

Interleukin-1ß triggers muscle-derived extracellular superoxide dismutase expression and protects muscles from doxorubicin-induced atrophy.

Doxorubicin, a conventional chemotherapeutic agent prescribed for cancer, causes skeletal muscle atrophy and adversely affects mobility and strength. Given that doxorubicin-induced muscle atrophy is attributable primarily to oxidative stress, its effects could be mitigated by antioxidant-focused therapies; however, these protective therapeutic targets remain ambiguous. The aim of this study was to demonstrate that doxorubicin triggers severe muscle atrophy via upregulation of oxidative stress (4-hydroxynonenal and malondialdehyde) and atrogenes (atrogin-1/MAFbx and muscle RING finger-1) in association with decreased expression of the antioxidant enzyme extracellular superoxide dismutase (EcSOD), in cultured C2C12 myotubes and mouse skeletal muscle. Supplementation with EcSOD recombinant protein elevated EcSOD levels on the cellular membrane of cultured myotubes, consequently inhibiting doxorubicin-induced oxidative stress and myotube atrophy. Furthermore, doxorubicin treatment reduced interleukin-1ß (IL-1ß) mRNA expression in cultured myotubes and skeletal muscle, whereas transient IL-1ß treatment increased EcSOD protein expression on the myotube membrane. Notably, transient IL-1ß treatment of cultured myotubes and local administration in mouse skeletal muscle attenuated doxorubicin-induced muscle atrophy, which was associated with increased EcSOD expression. Collectively, these findings reveal that the regulation of skeletal muscle EcSOD via maintenance of IL-1ß signalling is a potential therapeutic approach to counteract the muscle atrophy mediated by doxorubicin and oxidative stress. KEY POINTS: Doxorubicin, a commonly prescribed chemotherapeutic agent for patients with cancer, induces severe muscle atrophy owing to increased expression of oxidative stress; however, protective therapeutic targets are poorly understood. Doxorubicin induced muscle atrophy owing to increased expression of oxidative stress and atrogenes in association with decreased protein expression of extracellular superoxide dismutase (EcSOD) in cultured C2C12 myotubes and mouse skeletal muscle. Supplementation with EcSOD recombinant protein increased EcSOD levels on the cellular membrane of cultured myotubes, resulting in inhibition of doxorubicin-induced oxidative stress and myotube atrophy. Doxorubicin treatment decreased interleukin-1ß (IL-1ß) expression in cultured myotubes and skeletal muscle, whereas transient IL-1ß treatment in vivo and in vitro increased EcSOD protein expression and attenuated doxorubicin-induced muscle atrophy. These findings reveal that regulation of skeletal muscle EcSOD via maintenance of IL-1ß signalling is a possible therapeutic approach for muscle atrophy mediated by doxorubicin and oxidative stress.