Search Results (513)

Sarcopenia is characterized by a reduction in muscle function and skeletal muscle mass relative to that of healthy individuals. In older adults and those who are less resistant to sarcopenia, glucocorticoid secretion or accumulation during treatment exacerbates muscle protein degradation, potentially causing sarcopenia. This study assessed the preventive effects and mechanisms of heat-killed Lactobacillus plantarum postbiotic beLP-K (beLP-K) against dexamethasone (DEX)-induced sarcopenia in C2C12 myotubes and Sprague-Dawley rats. The administration of beLP-K did not induce cytotoxicity and mitigated cell damage caused by DEX. Furthermore, beLP-K significantly reduced the expression of forkhead box O3 α (FoxO3α), muscle atrophy f-box (MAFbx)/atrogin-1, and muscle RING-finger protein-1 (MuRF1), which are associated with muscle protein degradation. DEX induced weight loss in rats; however, in the beLP-K group, weight gain was observed. Micro-computed tomography analysis revealed that beLP-K increased muscle mass, correlating with weight and grip strength. beLP-K alleviated the DEX-induced reduction in grip strength and increased the mass of hind leg muscles. The correlation between beLP-K administration and increased muscle mass was associated with decreased expression levels of muscle degradation-related proteins such as MAFbx/atrogin-1 and MuRF1. Therefore, beLP-K may serve as a treatment for sarcopenia or as functional food material. Full article

The postmortem interval (PMI), defined as the time elapsed between death and the discovery or examination of the body, is a crucial parameter in forensic science for estimating the time of death. There are many ways to measure the PMI, such as Henssge’s nomogram, which uses rectal temperature measurement; livor mortis; rigor mortis; and forensic entomology. However, these methods are usually affected by various conditions in the surrounding environment. The purpose of the present study was to compare molecular genetics and histological changes in the brain and skeletal muscle tissues of SD rats over increasing periods of time after death. For the PMIs, we considered 0 h, 6 h, 12 h, 24 h, 36 h, 48 h, 4 days, 6 days, 8 days, 10 days, 14 days, and 21 days and compared them at 4 °C and 26 °C. Hematoxylin and Eosin (H&E) staining was performed to observe tissue changes. Morphological tissue changes were observed in cells for up to 21 days at 4 °C, and cell destruction was visually confirmed after 14 days at 26 °C. Total RNA (tRNA) was isolated from each tissue sample, and complementary DNA (cDNA) was synthesized. A reverse transcription quantitative PCR (RT-qPCR) SYBR Green assay targeting three types of housekeeping genes, including Gapdh, Sort1, B2m, and 5S rRNA, was performed. The results showed that Gapdh and 5S rRNA were highly stable and could be better RNA targets for estimating the PMI in brain and skeletal muscle tissues. Conversely, Sort1 and B2m showed poor stability and low expression levels. In conclusion, these molecular biomarkers could be used as auxiliary indicators of the PMI in human, depending on the stability of the marker. Full article

The decline in differentiation capacity during skeletal muscle (SkM) aging contributes to the deterioration of skeletal muscle function and impairs regenerative ability. Epicatechin gallate (ECG), a major functional component of catechins found in tea, has an unclear role in aging-related sarcopenia. In vivo experiments in 54-week-old C57BL/6J mice showed that ECG treatment improved exercise performance, muscle mass, and fiber morphology and downregulated the expression of the testosterone metabolic enzyme gene UGT2A3 in aged mice. In vitro experiments with Leydig cells (TM3) demonstrated that ECG upregulated the mRNA and protein expression levels of testosterone synthase genes, including StAR, P450scc, 3β-HSD, CYP17a1, and 17β-HSD. Network pharmacology analysis further suggested that ECG can influence testosterone secretion through the regulation of cytokines, thereby promoting skeletal muscle differentiation. These findings indicate that ECG enhances the differentiation of skeletal muscle cells by modulating testosterone levels, which helps alleviate age-related muscle function decline. Full article

Sarcopenia, the age-related loss of skeletal muscle mass and function, is associated with inflammation, mitochondrial dysfunction, and gut barrier impairment. This study investigates the postbiotic effects of heat-killed Lactiplantibacillus plantarum HY7715 (HY7715) and its extracellular vesicles (EVs) on muscle health and intestinal integrity. In C2C12 myotubes, both treatments enhanced myogenic differentiation by upregulating Myf5 and MYOG, and improved mitochondrial activity and biogenesis via increased PGC1α and mTOR expression. Under TNFα-induced muscle atrophy, they suppressed expression of atrophy-related markers (Fbox32, MuRF1, and myostatin). EVs showed stronger anti-inflammatory effects by reducing IL6 expression in muscle cells. In intestinal Caco-2 cells, HY7715-derived EVs improved barrier function by upregulating tight junction proteins (ZO-1, occludin, and claudins), and effectively reduced LPS-induced inflammation. These findings suggest that heat-killed HY7715 and its EVs may alleviate sarcopenia by enhancing muscle regeneration and maintaining intestinal homeostasis, highlighting their potential as safe, gut–muscle axis-targeting postbiotic interventions for healthy aging. Full article

Disused muscle atrophy (DMA) is characterized by skeletal muscle loss and functional decline due to prolonged inactivity. Though evidence remains limited, recent studies suggest that ferroptosis, an iron-dependent, lipid peroxidation-driven form of cell death, may contribute to DMA. Taurine, a natural amino acid enriched in energy drinks, can improve the proliferation and myogenic differentiation potential of myoblasts. This study aimed to investigate whether taurine supplementation could protect against DMA and explore its potential role in modulating ferroptosis. Using a hindlimb suspension-induced DMA model in male C57BL/6J mice (6–8 weeks old), we assessed muscle mass, function, ferroptosis-related markers, histopathological changes, and metabolic alterations. The results showed that taurine supplementation improved muscle strength and morphology while attenuating markers of ferroptosis, including iron accumulation, lipid peroxidation, and glutathione and related protein (NRF2, GPX4, and xCT) depletion. Metabolomic analysis suggested that taurine modulates disorders in glutathione and lipid metabolism, potentially associated with the regulation of the xCT-GSH-GPX4 and AMPK-ACC-ACSL4 pathways. While these findings support a protective role for taurine and a possible link between ferroptosis and DMA, further functional studies are needed to confirm causality and assess the compound’s translational potential. This study provides initial in vivo evidence implicating ferroptosis in DMA and highlights taurine as a promising candidate for future therapeutic exploration. Full article

Skeletal muscle is the largest heterogeneous organ in the body, and multiple factors in intrinsic genetic and epigenetic regulation influence its growth. The N⁶-methyladenosine ed(m⁶A) modification is a conserved and most prevalent RNA modification, whose function is dependent on m⁶A writers, erasers, and m⁶A readers, such as the YTH protein family. YTHDC1 is the only member of the YTH protein family member that exists in the cell nucleus, which plays an important role in mRNA alternative polyadenylation and alternative splicing processes. However, the function of YTHDC1 in regulating myoblast proliferation, differentiation, and in vivo skeletal muscle development remains unclear. Therefore, in this study, we studied the function of YTHDC1 in C2C12 cell line and mouse. Our results showed that YTHDC1 significantly promoted myogenic differentiation while inhibiting myoblast proliferation in C2C12 cells, and the results of our in vivo experiment showed that interfering with YTHDC1 led to a significant enhancement of muscle growth in mice. Furthermore, the transcriptome sequencing analysis revealed that YTHDC1 might modulate skeletal muscle development by regulating alternative splicing of genes, including Akap13, Smarca2, Tnnt3, and Neb. Our study shed light on understanding the function and molecular mechanisms of YTHDC1 in regulating skeletal muscle development, highlighting the critical contribution of m⁶A-mediated RNA splicing in muscle growth. These results indicated that YTHDC1 could be a potential breeding target gene to enhance meat quality in livestock. Full article

Background/Objectives: Medium-chain fatty acids (MCFAs), abundant in coconut oil, have attracted considerable attention in recent years owing to their potential impact on muscle atrophy. However, the mechanisms underlying their effects remain inadequately understood. This study aimed to examine the impact of coconut-oil-derived MCFAs on skeletal muscle in a mouse model administered a high-fat diet. Methods: C57BL/6J mice were assigned to a normal diet, lard diet, or coconut oil diet and maintained for a duration of 12 weeks. A glucose tolerance test was conducted, and biochemical parameters, muscle histological analysis, and gene expression in muscle tissue were assessed. MCFA concentrations in serum and muscle were quantified utilizing gas chromatography–mass spectrometry. An in vitro experiment was conducted by treating mouse C2C12 myotube cells with lauric acid and palmitic acid, followed by a gene expression evaluation. Results: Mice fed a coconut-oil-based diet exhibited reduced body weight gain and lower blood glucose and total cholesterol levels compared to those fed a lard-based diet. The coconut-oil-fed group showed increased concentrations of MCFAs in both serum and muscle tissue, along with an improvement in relative grip strength. The expression levels of proteins and genes associated with muscle atrophy were reduced in muscle tissue. These findings were corroborated in vitro using C2C12 myotube cells. Conclusions: Coconut oil may preserve muscle strength by increasing MCFA concentrations in serum and muscle tissue, while suppressing the expression of muscle-atrophy-related proteins and genes. These findings suggest that coconut oil may be beneficial in preventing muscle atrophy induced by long-chain fatty acids. Full article

Muscle loss unresponsive to nutritional supplementation affects up to 80% of cancer patients and severely reduces survival and treatment response. Exercise may help preserve muscle mass and function, yet the translatability of preclinical methods remains questionable. This study aimed to assess how voluntary wheel running, a clinically relevant physical activity, protects skeletal and cardiac muscle against cancer-mediated dysfunction and identify underlying molecular mechanisms. Methods: BALB/c mice were assigned to sedentary nontumor-bearing (SED+NT), sedentary tumor-bearing (SED+T), wheel run nontumor-bearing (WR+NT), and wheel run tumor-bearing (WR+T). Tumor-bearing groups received 5 × 10⁵ C26 cells; WR mice had wheel access for 4 weeks. Muscle function and tissue were analyzed for protective mechanisms. Results: SED+T mice exhibited significant fat and lean mass loss, indicating cachexia, which was prevented in WR+T mice. SED+T also showed 15% reduced grip strength and cardiac dysfunction, while WR+T preserved function. WR+T mice had lower expression of muscle wasting markers (Atrogin1, MuRF1, GDF15, GDF8/11). Physical activity also reduced tumor mass by 57% and volume by 37%. Conclusion: Voluntary wheel running confers tumor-suppressive, myoprotective, and cardioprotective effects. These findings support physical activity as a non-pharmacological strategy to combat cancer-related muscle wasting and dysfunction. Full article

Skeletal muscle diseases often exhibit fiber-type-specific characteristics and pose substantial clinical challenges, necessitating innovative therapies. The extracellular matrix (ECM) plays a pivotal role in muscle physiology and regeneration, influencing cell differentiation. However, its specific role and mechanisms influencing muscle fiber type specification remain insufficiently understood. In this study, C2C12^GFP myoblasts were differentiated into myofibers on plates coated with fibronectin, Collagen I, and Geltrex™. Differentiation occurred successfully across all ECM substrates, resulting in myofiber formation. Quantitative polymerase chain reaction (qPCR) analysis confirmed myogenic marker expression patterns, indicating decreased Pax7 and increased Myog levels by day 7. Protein analysis through Western blot and immunofluorescence assays along with transcriptomic profiling through RNA sequencing consistently indicated that Collagen I promoted slow-type fibers development, as evidenced by increased slow myofiber protein expression and the upregulation of slow fiber-associated genes, potentially mediated by pathways involving calcineurin/NFAT, MEF2, MYOD, AMPK, PI3K/AKT, and ERK1. In contrast, fibronectin and Geltrex™ led to fast-type fiber development, with elevated fast-type fiber protein levels and upregulation of fast fiber-associated genes, possibly through activation of HIF1A, FOXO1, NFKB, and ERK2. These findings elucidate ECM-mediated muscle fiber type differentiation mechanisms, informing future targeted therapies for muscle regeneration. Full article

Skeletal muscle satellite cells are muscle stem cells that play an important role in the growth, development, and repair of skeletal muscle as well as in the locomotor performance of the animal body. Lysine is the first limiting amino acid and is involved in multiple metabolic pathways in the organism to maintain overall physiological requirements. In this study, Mongolian horse satellite cells were cultured using lysine culture solution at different concentrations, and the proliferative capacity of satellite cells was detected by the cck-8 assay, and the optimal culture concentration was selected. Then, whole transcriptome sequencing technology was used to determine the differential gene expression and regulatory pathways during the proliferation of lysine-cultured satellite cells after 48 h of culture. Our findings revealed that 0.5 mmol/L lysine is the optimal concentration to increase satellite cell activity in equine muscle. The differential genes involved in satellite cell proliferation were mainly enriched in the cAMPsignaling pathway, calcium signaling pathway, and PPAR signaling pathway. Furthermore, upregulation of PLIN5, ACADL, and FADS2 and downregulation of LOC100052888 regulated the expression of the PPAR signaling pathway. 0.5 mmol/L lysine was the optimal concentration to increase satellite cell activity. Lysine can regulate mitochondrial function and lipid metabolism through the PPAR signaling pathway, and promote the proliferation of equine myosatellite cells. Full article

In fibrotic skeletal muscles, excessive extracellular matrix (ECM) deposition is a result of increased activation and decreased apoptosis of myofibroblasts. The aim of this study is to investigate whether treatment with quercetin, kaempferol or capsaicin can reduce the transforming growth factor-beta 1 (TGF-β1)-induced myofibroblast differentiation and fibrotic ECM expression in differentiated C2C12 cells. Two-day-differentiated C2C12 cells were treated with TGF-β1 for 48 h to induce myofibroblast differentiation. Twenty-four hours before (pre-treatment) and for forty-eight hours with (co-treatment) TGF-β1 treatment, cells were exposed to quercetin (25, 50 µM), kaempferol (10, 25, 50 µM) or capsaicin (25, 50 µM). The immunofluorescence intensity of alpha smooth muscle actin (αSMA) and collagen type I/III gene expression were assessed as myofibroblast markers. MyoD immunofluorescence intensity was measured as a myogenic marker. Co-treatment of TGF-β1 with the phytochemicals was most effective, resulting in a decreased number of αSMA-positive cells (all three compounds), decreased collagen type I (kaempferol, capsaicin) and type III (kaempferol) gene expression, and increased MyoD (kaempferol, capsaicin) protein expression compared to TGF-β1 treatment. This study demonstrates that treatment with quercetin, kaempferol or capsaicin can reduce myofibroblast markers. This suggests a possible anti-fibrotic effect of the phytochemicals in skeletal muscle. Full article

Fish red blood cells (RBCs) are nucleated, transcriptionally active, and key players in both gas transport and immune responses. They are the primary targets of Orthoreovirus piscis (PRV), the etiological agent of heart and skeletal muscle inflammation (HSMI), which includes three genotypes (PRV-1, PRV-2, and PRV-3), linked to circulatory disorders in farmed salmon. In Chile, PRV-3 affects the coho salmon (Oncorhynchus kisutch), but host–pathogen interactions remain poorly characterized. This study compared the interactions of PRV-3 in coho salmon and PRV-1 in Atlantic salmon (Salmo salar) using RBC infection models. RBCs were isolated from healthy juvenile salmon (n = 3) inoculated with either PRV-1 (Ct = 18.87) or PRV-3 (Ct = 21.86). Poly I:C (50 µg/mL) was used as a positive control for the antiviral response. Cells were monitored for up to 14 days post-infection (dpi). PRV-3 infection in coho salmon RBCs caused significant metabolic disruption, apoptosis from 7 dpi, and correlated with increasing viral loads. In contrast, PRV-1 infection in Atlantic salmon RBCs showed limited apoptosis and maintained cell viability. Coho salmon RBCs upregulated rig-i, mx, and pkr transcripts, indicating activation of the type I interferon pathway, whereas Atlantic salmon RBCs exhibited a more attenuated response. PRV-3 induced notable morphological changes in coho salmon RBCs, although neither PRV-3 nor PRV-1 caused hemolysis. These findings highlight species-specific differences in RBC responses to PRV infection and provide new insights into the pathogenesis of PRV-3 and PRV-1. Full article

Type 1 Diabetes Mellitus (T1D) is a disease characterized by the destruction of pancreatic beta cells. The subsequent loss of insulin production results in hyperglycemia, muscle wasting, and vascular dysfunction. Due to an inability to appropriately maintain glucose homeostasis, patients afflicted with T1D suffer from increased morbidity and early mortality. Skeletal muscle is the body’s largest metabolic reservoir, absorbing significant amounts of glucose from the bloodstream and physical exercise is known to improve and prevent the progression of pathological outcomes, but many T1D patients are unable to exercise at a level that conveys benefit. Thus, directly targeting muscle mass and function may prove beneficial for improving T1D patient outcomes, independent of exercise. A potent negative regulator of skeletal muscle has been identified as being upregulated in T1D patients, namely the myokine myostatin. Our hypothesis is that targeting myostatin (via genetic deletion) will prevent glucose dysfunction in a T1D model, preserve skeletal muscle function, and protect against vascular and renal dysfunction. Our methods utilized adult male mice with (WT) and without myostatin (Myo KO), in combination with the chemical induction of T1D (streptozotocin). Experimental outcomes included the assessment of glucose homeostasis (plasma glucose, HbA1c, IGTT), metabolism, muscle function (in vivo plantarflexion), and skeletal muscle vascular function (ex vivo pressure myography). Our results described systemic benefits from myostatin deletion in the T1D model, independent of insulin, including the following: inhibition of T1D-induced increases in plasma glucose, prevention of functional deficits in muscle performance, and preservation of fluid dynamics. Further, endothelial function was preserved with myostatin deletion. Taken together, these data inform upon the use of myostatin inhibition as a therapeutic target for effective treatment and management of the cardiometabolic and skeletal muscle dysfunction that occurs with T1D. Full article

Background: Survivors of hematopoietic stem cell transplantation (HSCT) during childhood face significant late effects. This study aimed to map the dietary micronutrient intake of long-term survivors of pediatric HSCT and explore its associations with transplant outcomes, body composition, and physical capacity. Methods: We included 85 long-term survivors of HSCT (median age 30 years) The median time since HSCT was 19.9 years, reflecting a long-term survivor population. Dietary intake was assessed using a 3-day food record. Body composition was measured by DXA, and physical capacity was evaluated through cardiorespiratory fitness and physical performance tests. Results: We observed an inadequate intake of several vitamins and minerals including vitamins A, C, D, E, selenium, and potassium, with a median intake below recommendations. While dietary intake of vitamin D was reduced in patients with chronic graft versus host disease (cGvHD), the occurrence of cGvHD was not associated with overall micronutrient intake. Twelve percent of the participants had reduced skeletal muscle mass and 16% displayed a low bone mass density during DXA scans. These conditions were not related to the micronutrient intake. Likewise, reduced cardiorespiratory fitness and physical performance were unrelated to micronutrient intake. Total energy intake was found to significantly influence micronutrient intake (p = 0.001), explaining 66% of the variation. Conclusions: Long-term survivors of pediatric HSCT demonstrated inadequate intake of multiple micronutrients. These findings suggest that inclusion of comprehensive micronutrient assessment and nutritional guidance should be considered for inclusion in follow-up care protocols. Full article

Background: Muscle loss during sarcopenia and atrophy is also commonly associated with age-related insulin resistance. Interestingly, branched-chain amino acids (BCAA) which are known for stimulating muscle protein synthesis are commonly elevated during insulin resistance and sarcopenic obesity. Objectives: This study investigated the effects of the interplay between atrophy and insulin resistance on insulin sensitivity, mitochondrial metabolism, and BCAA catabolic capacity in a myotube model of skeletal muscle insulin resistance. Methods: C2C12 myotubes were treated with dexamethasone to induce atrophy. Insulin resistance was induced via hyperinsulinemia. Gene and expression were measured using qRT-PCR and Western blot, while mitochondrial and lipid content were assessed using fluorescent staining. Cell metabolism was analyzed via Seahorse metabolic assays. Results: Both dexamethasone-induced atrophy and insulin resistance independently reduced insulin-stimulated pAkt levels, as well as mitochondrial function and content. However, neither treatment affected gene or protein expression associated with mitochondrial biogenesis or content. Although dexamethasone independently reduced insulin sensitivity in otherwise previously insulin-sensitive cells, dexamethasone had no significant effect on extracellular BCAA content. Conclusions: Our findings indicate the metabolic interplay between atrophy and insulin resistance and demonstrate that both can reduce mitochondrial function, though only limited effects were observed on indicators of BCAA catabolism and utilization. This emphasizes the need for future studies to investigate the mechanisms that underlie atrophy and other metabolic disorders to develop new interventions. Full article