EPA and DHA Inhibit Myogenesis and Downregulate the Expression of Muscle-related Genes in C2C12 Myoblasts

Cordycepin inhibits myogenesis via activating the ERK1/2 MAPK signalling pathway in C2C12 cells

Cordycepin (with a molecular formula of C10H13N5O3), a natural adenosine isolated from Cordyceps militaris, has an important regulatory effect on skeletal muscle remodelling and quality maintenance. The aim of this study was to investigate the effect of cordycepin on myoblast differentiation and explore the underlying molecular mechanisms of this effect. Our results showed that cordycepin inhibited myogenesis by downregulating myogenic differentiation (MyoD) and myogenin (MyoG), preserved undifferentiated reserve cell pools by upregulating myogenic factor 5 (Myf5) and retinoblastoma-like protein p130 (p130), and enhanced energy reserves by decreasing intracellular reactive oxygen species (ROS) and enhancing mitochondrial membrane potential, mitochondrial mass, and ATP content. The effect of cordycepin on myogenesis was associated with increased phosphorylation of extracellular signal-regulated kinase 1/2 (p-ERK1/2). PD98059 (a specific inhibitor of p-ERK1/2) attenuated the inhibitory effect of cordycepin on C2C12 differentiation. The present study reveals that cordycepin inhibits myogenesis through ERK1/2 MAPK signalling activation accompanied by an increase in skeletal muscle energy reserves and improving skeletal muscle oxidative stress, which may have implications for its further application for the prevention and treatment of degenerative muscle diseases caused by the depletion of depleted muscle stem cells.

Linoleic acid-induced ANGPTL4 inhibits C2C12 skeletal muscle differentiation by suppressing Wnt/β-catenin

Skeletal muscle differentiation is an essential process in embryonic development as well as regeneration and repair throughout the lifespan. It is well-known that dietary fat intake impacts biological and physiological function in skeletal muscle, however, understanding of the contribution of nutritional factors in skeletal muscle differentiation is limited. Therefore, the objective of the current study was to evaluate the effects of free fatty acids (FFAs) on skeletal muscle differentiation in vitro. We used C2C12 murine myoblasts and treated them with various FFAs, which revealed a unique response of angiopoietin-like protein-4 (ANGPTL4) with linoleic acid (LA) treatment that was associated with reduced differentiation. LA significantly inhibited myotube formation and lowered the protein expression of myogenic regulatory factors, including MyoD and MyoG and increased Pax7 during cell differentiation. Next, recombinant ANGPTL4 protein or siRNA knockdown of ANGPTL4 was employed to examine its role in skeletal muscle differentiation, and we confirmed that ANGPTL4 knockdown at day 2 and -6 of differentiation restored myotube formation in the presence of LA. RNA-sequencing analysis revealed that ANGPTL4-mediated inhibition of skeletal muscle differentiation at day 2 as well as LA at day 2 or -6 led to a reduction in Wnt/β-catenin signaling pathways. We confirmed that LA reduced Wnt11 and Axin2 while increasing expression of the Wnt inhibitor, Dkk2. ANGPTL4 knockdown increased β-catenin protein in the nucleus in response to LA and increased Axin2 and Wnt11 expression. Taken together, these results demonstrate that LA induced ANGPTL4 inhibits C2C12 differentiation by suppressing Wnt/β-catenin signaling.

The Role of Omega-3 Polyunsaturated Fatty Acids and Their Lipid Mediators on Skeletal Muscle Regeneration: A Narrative Review

Skeletal muscle is the largest tissue in the human body, comprising approximately 40% of body mass. After damage or injury, a healthy skeletal muscle is often fully regenerated; however, with aging and chronic diseases, the regeneration process is usually incomplete, resulting in the formation of fibrotic tissue, infiltration of intermuscular adipose tissue, and loss of muscle mass and strength, leading to a reduction in functional performance and quality of life. Accumulating evidence has shown that omega-3 (n-3) polyunsaturated fatty acids (PUFAs) and their lipid mediators (i.e., oxylipins and endocannabinoids) have the potential to enhance muscle regeneration by positively modulating the local and systemic inflammatory response to muscle injury. This review explores the process of muscle regeneration and how it is affected by acute and chronic inflammatory conditions, focusing on the potential role of n-3 PUFAs and their derivatives as positive modulators of skeletal muscle healing and regeneration.

Effects of Late Gestation Supplements Differing in Fatty Acid Amount and Profile to Beef Cows on Cow Performance, Steer Progeny Growth Performance through Weaning, and Relative mRNA Expression of Genes Associated with Muscle and Adipose Tissue Development

Strategic supplementation during late gestation has the potential to alter progeny performance. Mature fall-calving Simmental × Angus cows were used to evaluate the effects of late gestation supplementation of fatty acids to beef cows on cow performance, steer progeny growth performance during pre-weaning and backgrounding periods, and relative mRNA expression of genes associated with myogenesis and adipogenesis. Cows (n = 190; 4 pasture groups of cows/treatment) grazed endophyte-infected tall fescue and were supplemented during late gestation with calcium salts of either saturated fatty acid/monounsaturated fatty acid (SFA/MUFA), polyunsaturated fatty acid (PUFA), or an isocaloric and isonitrogenous control (CON). There were no differences (p ≥ 0.11) in cow body weight (BW) or body condition scores from pre-supplementation to weaning or steer BW at birth, weaning, or at the end of the backgrounding period. Concentrations of C18:2n-6 in plasma were greater (p = 0.01) in SFA/MUFA and PUFA cows compared to CON cows during supplementation. For mRNA expression in the longissimus muscle of steer progeny from birth to weaning: PAX7 decreased to a greater (p < 0.01) extent for SFA/MUFA and PUFA steers; AGPAT1 and CPT1 increased to a greater (p ≤ 0.02) extent for CON steers. The expression of MYH7 mRNA during the pre-weaning period was greater (p = 0.01) in PUFA. In conclusion, late gestation fatty acid supplementation modified plasma relative concentrations of fatty acids for dams and progeny and modified mRNA expression of genes related to myogenesis and adipogenesis but had limited effects on progeny growth performance during pre-weaning and backgrounding periods.

The Effects of Maternal Intake of EPA and DHA Enriched Diet During Pregnancy and Lactation on Offspring's Muscle Development and Energy Homeostasis

EPA and DHA are n-3 long-chain polyunsaturated fatty acids with a diversity of health benefits on offspring. The objective of this study was to test the in vivo effect of maternal ingestion of EPA and DHA on fetal and offspring muscle development and energy balance. Two groups of female C57BL/6 mice were fed EPA and DHA enriched diet (FA) and diet devoid of EPA and DHA (CON) respectively throughout the entire period of gestation and lactation. Embryos at E13 and offspring at age of D1 and D21 were selected for sample collection and processing. No change in birth number and body weight were observed between groups at D1 and D21. Transient increase in the expression levels of myogenesis regulating genes was detected at D1 (p < 0.05) in FA group. Most of the expression of muscle protein synthesis regulating genes were comparable (p > 0.05) between FA and CON groups at D1 and D21. The significant increase in MHC4, and IGF-1 was not linked to increased muscle mass. A persistent increase in ISR expression (p < 0.05) but not in GLUT-4 (p > 0.05) was detected in offspring. Up-regulation of adipogenesis regulating genes was accompanied by increasing intramuscular fat accumulation in the offspring of FA group. Considerable increase in transcripts of genes regulating lipid catabolism and thermogenesis in liver (p < 0.05) was noticed in FA group at D21; whereas, only the levels of carnitine palmitoyl transferase 1A (Cpt1α) and Enoyl-CoA Hydratase And 3-Hydroxyacyl CoA Dehydrogenase (Ehhadh) increased at D1. Similarly, genes regulating lipolysis were highly expressed at D21 in FA group. EPA and DHA treatment promoted BAT development and activity by increasing the expression of BAT signature genes (p < 0.05). Also, maternal intake of EPA and DHA enriched diet enhanced browning of sWAT. Taken together, maternal ingestion of EPA/DHA may be suggested as a therapeutic option to improve body composition and counteract childhood obesity- related metabolic disorders and confer lifelong positive metabolic impact on offspring.

Low n-6/n-3 Gestation and Lactation Diets Influence Early Performance, Muscle and Adipose Polyunsaturated Fatty Acid Content and Deposition, and Relative Abundance of Proteins in Suckling Piglets

Elevated omega-6 (n-6) and omega-3 (n-3) polyunsaturated fatty acids (PUFAs) ratios in swine diets can potentially impose a higher risk of inflammatory and metabolic diseases in swine. A low ratio between the two omega PUFAs has beneficial effects on sows' and piglets' production performance and immunity status. At present, there are few studies on how sow nutrition directly affects the protein and fat deposition in suckling piglets. Two groups of sows were fed diets with high or low n-6/n-3 polyunsaturated ratios of 13:1 (SOY) and 4:1 (LIN), respectively, during gestation and lactation. Longissimus dorsi muscle and adipose tissue from newborn piglets, nourished only with sow's milk, were subjected to fatty acid profiling by gas chromatography-mass spectrometry (GC-MS) and to proteomics assays based on nano-liquid chromatography coupled to high-resolution tandem mass spectrometry (nLC-HRMS). Fatty acid profiles on both muscle and adipose tissues resembled the magnitude of the differences between fatty acid across diets. Proteomic analysis revealed overabundance of 4 muscle and 11 adipose tissue proteins in SOY compared to LIN in both piglet tissues. The detected overabundance of haptoglobin, an acute-phase protein, and the stimulation of protein-coding genes and proteins related to the innate immune response and acute inflammatory response could be associated with the pro-inflammatory role of n-6 PUFAs.

Silibinin Alleviates Muscle Atrophy Caused by Oxidative Stress Induced by Cisplatin through ERK/FoxO and JNK/FoxO Pathways

Cisplatin (DDP), a widely used chemotherapeutic drug in cancer treatment, causes oxidative stress, resulting in cancer cachexia and skeletal muscle atrophy. This study investigated the effects and activity of silibinin (SLI) in reducing DDP-induced oxidative stress and skeletal muscle atrophy in vivo and in vitro. SLI alleviated weight loss, food intake, muscle wasting, adipose tissue depletion, and organ weight reduction induced by DDP and improved the reduction of grip force caused by DDP. SLI can attenuated the increase in reactive oxygen species (ROS) levels, the decrease in Nrf2 expression, the decrease in the fiber cross-sectional area, and changes in fiber type induced by DDP. SLI regulated the ERK/FoxO and JNK/FoxO pathways by downregulating the abnormal increase in ROS and Nrf2 expression in DDP-treated skeletal muscle and C2C12 myotube cells. Further, SLI inhibited the upregulation of MAFbx and Mstn, the downregulation of MyHC and MyoG, the increase in protein degradation, and the decrease of protein synthesis. The protective effects of SLI were reversed by cotreatment with JNK agonists and ERK inhibitors. These results suggest that SLI can reduce DDP-induced skeletal muscle atrophy by reducing oxidative stress and regulating ERK/FoxO and JNK/FoxO pathways.

Effects of omega-7 palmitoleic acids on skeletal muscle differentiation in a hyperglycemic condition

Maternal obesity and diabetes are known to be involved in fetal myogenesis, but the later stages of myogenesis are not well understood. In this study, we investigated the influence of a hyperglycemic environment on L6 skeletal myoblast differentiation and the function of omega-7 palmitoleic acids. Exposure to a high concentration of glucose (25 mM) in high-glucose culture medium (HG) increased the expression of myogenic genes (MyoD, Myogenin, MRF4, Myhc2x, and Myhc2a) and the synthesis of myosin. HG also activated the PI3K/AKT pathway revealed muscle cell differentiation. Furthermore, the levels of reactive oxygen species (ROS) and an inflammatory cytokine (Tnfaip3; tumor necrosis factor alpha-induced protein 3), which are crucial for the growth and differentiation of skeletal muscle, were increased by HG. Palmitoleic acids suppressed the expression levels of myogenic regulatory genes and increased the expression level of a cell proliferation-related gene (Pax3). Trans-palmitoleic acid and eicosapentaenoic acid (TPA and EPA) increased the phosphorylation level of MAPK/ERK1/2 and downregulated ROS generation and Tnfaip3 expression. In contrast, cis-palmitoleic acid inactivated MAPK/ERK1/2, leading to increased ROS generation. In conclusion, a hyperglycemic environment mediated by HG induced excessive muscle differentiation. Palmitoleic acids inhibited myoblast differentiation by downregulating muscle-specific genes. Moreover, trans-palmitoleic acids may have beneficial antioxidant and/or anti-inflammatory effects in cells.

Effects of supplements differing in fatty acid profile to late gestational beef cows on cow performance, calf growth performance, and mRNA expression of genes associated with myogenesis and adipogenesis

Background

Maternal nutrition during gestation affects fetal development, which has long-term programming effects on offspring postnatal growth performance. With a critical role in protein and lipid metabolism, essential fatty acids can influence the development of muscle and adipose tissue. The experiment investigated the effects of late gestation supplements (77 d prepartum), either rich in saturated and monounsaturated fatty acids (CON; 155 g/cow/d EnerGII) or polyunsaturated fatty acids (PUFA; 80 g/cow/d Strata and 80 g/cow/d Prequel), on cow performance and subsequent calf growth performance as well as mRNA expression in longissimus muscle (LM) and subcutaneous adipose tissue at birth and weaning.

Results

There was no difference (P ≥ 0.34) in cow body weight (BW) or body condition score from pre-supplementation through weaning. Relative concentrations of C18:3n-3 and C20:4n-6 decreased (P ≤ 0.05) to a greater extent from mid-supplementation to calving for PUFA compared with CON cows. Cow plasma C20:0, C20:5n-3, and C22:6n-3 were increased (P ≤ 0.01) in PUFA during supplementation period. At birth, PUFA steers had greater (P = 0.01) plasma C20:5n-3. No differences (P ≥ 0.33) were detected in steer birth BW or dam milk production, however, CON steers tended (P = 0.06) to have greater pre-weaning average daily gain and had greater (P = 0.05) weaning BW compared with PUFA. For mRNA expression in steers: MYH7 and C/EBPβ in LM increased (P ≤ 0.04) to a greater extent from birth to weaning for PUFA compared with CON; MYF5 in LM and C/EBPβ in adipose tissue tended (P ≤ 0.08) to decrease more from birth to weaning for CON compared with PUFA; SCD in PUFA adipose tissue tended (P = 0.08) to decrease to a greater extent from birth to weaning than CON. In addition, maternal PUFA supplementation tended (P = 0.08) to decrease MYOG mRNA expression in LM and decreased (P = 0.02) ZFP423 in adipose tissue during the pre-weaning stage.

Conclusions

Late gestation PUFA supplementation decreased pre-weaning growth performance of the subsequent steer progeny compared with CON supplementation, which could have been a result of downregulated mRNA expression of myogenic genes during pre-weaning period.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-021-00588-w.

Regulation of Skeletal Muscle Satellite Cell Differentiation by Omega-3 Polyunsaturated Fatty Acids: A Critical Review

Skeletal muscle is composed of multinuclear cells called myofibres, which are formed by the fusion of myoblasts during development. The size of the muscle fiber and mass of skeletal muscle are altered in response to several pathological and physiological conditions. Skeletal muscle regeneration is primarily mediated by muscle stem cells called satellite cells (SCs). In response to injury, these SCs replenish myogenic progenitor cells to form new myofibers to repair damaged muscle. During myogenesis, activated SCs proliferate and differentiate to myoblast and then fuse with one another to form muscle fibers. A reduced number of SCs and an inability to undergo myogenesis may contribute to skeletal muscle disorders such as atrophy, cachexia, and sarcopenia. Myogenic regulatory factors (MRF) are transcription factors that regulate myogenesis and determines whether SCs will be in the quiescent, activated, committed, or differentiated state. Mitochondria oxidative phosphorylation and oxidative stress play a role in the determination of the fate of SCs. The potential activation and function of SCs are also affected by inflammation during skeletal muscle regeneration. Omega-3 polyunsaturated fatty acids (PUFAs) show promise to reduce inflammation, maintain muscle mass during aging, and increase the functional capacity of the muscle. The aim of this critical review is to highlight the role of omega-3 PUFAs on the myogenic differentiation of SCs and pathways affected during the differentiation process, including mitochondrial function and inflammation from the current body of literature.

PUFA Treatment Affects C2C12 Myocyte Differentiation, Myogenesis Related Genes and Energy Metabolism

Polyunsaturated fatty acids (PUFAs) are the main components of cell membrane affecting its fluidity, signaling processes and play a vital role in muscle cell development. The effects of docosahexaenoic acid (DHA) on myogenesis are well known, while the effects of arachidonic acid (AA) are largely unclear. The purpose of this study is to evaluate the effect of two PUFAs (DHA and AA) on cell fate during myogenic processes, Wnt signaling and energy metabolism by using the C2C12 cells. The cells were treated with different concentrations of AA or DHA for 48 h during the differentiation period. PUFA treatment increased mRNA level of myogenic factor 5 (Myf5), which is involved in early stage of myoblast proliferation. Additionally, PUFA treatment prevented myoblast differentiation, indicated by decreased myotube fusion index and differentiation index in parallel with reduced mRNA levels of myogenin (MyoG). After PUFA withdrawal, some changes in cell morphology and myosin heavy chain mRNA levels were still observed. Expression of genes associated with Wnt signaling pathway, and energy metabolism changed in PUFA treatment in a dose and time dependent manner. Our data suggests that PUFAs affect the transition of C2C12 cells from proliferation to differentiation phase by prolonging proliferation and preventing differentiation.

The regulatory role of dietary factors in skeletal muscle development, regeneration and function

Skeletal muscle plays a crucial role in motor function, respiration, and whole-body energy homeostasis. How to regulate the development and function of skeletal muscle has become a hot research topic for improving lifestyle and extending life span. Numerous transcription factors and nutritional factors have been clarified are closely associated with the regulation of skeletal muscle development, regeneration and function. In this article, the roles of different dietary factors including green tea, quercetin, curcumin (CUR), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and resveratrol (RES) in regulating skeletal muscle development, muscle mass, muscle function, and muscle recovery have been summarized and discussed. We also reviewed the potential regulatory molecular mechanism of these factors. Based on the current findings, dietary factors may be used as a potential therapeutic agent to treat skeletal muscle dysfunction as well as its related diseases.

Transcriptomic Profile of Primary Culture of Skeletal Muscle Cells Isolated from Semitendinosus Muscle of Beef and Dairy Bulls

The aim of the study was to identify differences in the transcriptomic profiles of primary muscle cell cultures derived from the semitendinosus muscle of bulls of beef breeds (Limousin (LIM) and Hereford (HER)) and a dairy breed (Holstein-Friesian (HF)) (n = 4 for each breed). Finding a common expression pattern for proliferating cells may point to such an early orientation of the cattle beef phenotype at the transcriptome level of unfused myogenic cells. To check this hypothesis, microarray analyses were performed. The analysis revealed 825 upregulated and 1300 downregulated transcripts similar in both beef breeds (LIM and HER) and significantly different when compared with the dairy breed (HF) used as a reference. Ontological analyses showed that the largest group of genes were involved in muscle organ development. Muscle cells of beef breeds showed higher expression of genes involved in myogenesis (including erbb-3, myf5, myog, des, igf-1, tgfb2) and those encoding proteins comprising the contractile apparatus (acta1, actc1, myh3, myh11, myl1, myl2, myl4, tpm1, tnnt2, tnnc1). The obtained results confirmed our hypothesis that the expression profile of several groups of genes is common in beef breeds at the level of proliferating satellite cells but differs from that observed in typical dairy breeds.

Omega-3 Polyunsaturated Fatty Acids Mitigate Palmitate-Induced Impairments in Skeletal Muscle Cell Viability and Differentiation

Accumulation of excess saturated free fatty acids such as palmitate (PAL) in skeletal muscle leads to reductions in mitochondrial integrity, cell viability and differentiation. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) counteract PAL-induced lipid accumulation. EPA and DHA, as well as the n-3 PUFA docosapentaenoic acid (DPA), may therefore mitigate PAL-induced lipotoxicity to promote skeletal muscle cell survival and differentiation. C2C12 myoblasts were treated with 50 μM EPA, DPA, or DHA in the absence or presence of 500 μM PAL for 16 h either prior to myoblast analysis or induction of differentiation. Myoblast viability and markers of apoptosis, endoplasmic reticulum (ER) stress and myotube differentiation capacity were investigated using fluorescence microscopy and immunoblotting. High-resolution respirometry was used to assess mitochondrial function and membrane integrity. PAL induced cell death via apoptosis and increased protein content of ER stress markers BiP and CHOP. EPA, DPA, and DHA co-treatment maintained cell viability, prevented PAL-induced apoptosis and attenuated PAL-induced increases in BiP, whereas only DPA prevented increases in CHOP. PAL subsequently reduced protein content of the differentiation marker myogenin and inhibited myotube formation, and all n-3 PUFAs promoted myotube formation in the presence of PAL. Furthermore, DPA prevented PAL-induced release of cytochrome c and maintained mitochondrial integrity. These findings demonstrate the n-3 PUFAs EPA, DPA and DHA elicit similar protective effects against PAL-induced impairments in muscle cell viability and differentiation. Mechanistically, the protective effects of DPA against PAL lipotoxicity are attributable in part to its ability to maintain mitochondrial respiratory capacity via mitigating PAL-induced loss of mitochondrial membrane integrity.

Comparative Transcriptome Analysis Provides Insights into the Polyunsaturated Fatty Acid Synthesis Regulation of Fat-1 Transgenic Sheep

Transgenic technology has huge application potential in agriculture and medical fields, such as producing new livestock varieties with new valuable features and xenotransplantation. However, how an exogenous gene affects the host animal’s gene regulation networks and their health status is still poorly understood. In the current study, Fat-1 transgenic sheep were generated, and the tissues from 100-day abnormal (DAF_1) and normal (DAF_2) fetuses, postnatal lambs (DAF_4), transgenic-silencing (DAFG5), and -expressing (DAFG6) skin cells were collected and subjected to transcriptome sequencing, and their gene expression profiles were compared in multiple dimensions. The results were as follows. For DAF_1, its abnormal development was caused by pathogen invasion but not the introduction of the Fat-1 gene. Fat-1 expression down-regulated the genes related to the cell cycle; the NF-κB signaling pathway and the PI3K/Akt signaling pathway were down-regulated, and the PUFAs (polyunsaturated fatty acids) biosynthesis pathway was shifted toward the biosynthesis of high-level n-3 LC-PUFAs (long-chain PUFAs). Four key node genes, FADS2, PPARA, PRKACA, and ACACA, were found to be responsible for the gene expression profile shift from the Fat-1 transgenic 100-day fetus to postnatal lamb, and FADS2 may play a key role in the accumulation of n-3 LC-PUFAs in Fat-1 transgenic sheep muscle. Our study provides new insights into the FUFAs synthesis regulation in Fat-1 transgenic animals.

Divergent Regulation of Myotube Formation and Gene Expression by E2 and EPA during In-Vitro Differentiation of C2C12 Myoblasts

Estrogen (E2) and polyunsaturated fatty acids (n-3PUFA) supplements independently support general wellbeing and enhance muscle regeneration in-vivo and myotube formation in-vitro. However, the combined effect of E2 and n-3PUFA on myoblast differentiation is not known. The purpose of the study was to identify whether E2 and n-3PUFA possess a synergistic effect on in-vitro myogenesis. Mouse C2C12 myoblasts, a reliable model to reiterate myogenic events in-vitro, were treated with 10nM E2 and 50μM eicosapentaenoic acid (EPA) independently or combined, for 0-24 h or 0-120 h during differentiation. Immunofluorescence, targeted qPCR and next generation sequencing (NGS) were used to characterize morphological changes and differential expression of key genes involved in the regulation of myogenesis and muscle function pathways. E2 increased estrogen receptor α (Erα) and the expression of the mitogen-activated protein kinase 11 (Mapk11) within 1 h of treatment and improved myoblast differentiation and myotube formation. A significant reduction (p < 0.001) in myotube formation and in the expression of myogenic regulatory factors Mrfs (MyoD, Myog and Myh1) and the myoblast fusion related gene, Tmem8c, was observed in the presence of EPA and the combined E2/EPA treatment. Additionally, EPA treatment at 48 h of differentiation inhibited the majority of genes associated with the myogenic and striated muscle contraction pathways. In conclusion, EPA and E2 had no synergistic effect on myotube formation in-vitro. Independently, EPA inhibited myoblast differentiation and overrides the stimulatory effect of E2 when used in combination with E2.

Effect of dietary fish oil intake on ubiquitin ligase expression during muscle atrophy induced by sciatic nerve denervation in mice

Dietary fish oil intake improves muscle atrophy in several atrophy models however the effect on denervation-induced muscle atrophy is not clear. Thus, the aim of this study was to investigate the effects of dietary fish oil intake on muscle atrophy and the expression of muscle atrophy markers induced by sciatic nerve denervation in mice. We performed histological and quantitative mRNA expression analysis of muscle atrophy markers in mice fed with fish oil with sciatic nerve denervation. Histological analysis indicated that dietary fish oil intake slightly prevented the decrease of muscle fiber diameter induced by denervation treatment. In addition, dietary fish oil intake suppressed the MuRF1 (tripartite motif-containing 63) expression up-regulated by denervation treatment, and this was due to decreased tumor necrosis factor-alpha (TNF-α) production in skeletal muscle. We concluded that dietary fish oil intake suppressed MuRF1 expression by decreasing TNF-α production during muscle atrophy induced by sciatic nerve denervation in mice.