Intramuscular Lipid Research Articles

Serum Levels of Myonectin Are Lower in Adults with Metabolic Syndrome and Are Negatively Correlated with Android Fat Mass.

Myonectin has shown beneficial effects on lipid regulation in murine models; therefore, it may have implications in the pathophysiology of metabolic syndrome (MS). We evaluated the relationship between serum myonectin and serum lipids, global and regional fat mass, intramuscular lipid content, and insulin resistance (IR) in adults with metabolic risk factors. This was a cross-sectional study in sedentary adults who were diagnosed with MS or without MS (NMS). Serum myonectin was quantified by enzyme-linked immunosorbent assay, lipid profile by conventional techniques, and free fatty acids (FFA) by gas chromatography. Body composition was assessed by dual-energy X-ray absorptiometry and intramuscular lipid content through proton nuclear magnetic resonance spectroscopy in the right vastus lateralis muscle. IR was estimated with the homeostatic model assessment (HOMA-IR). The MS (n = 61) and NMS (n = 29) groups were comparable in age (median (interquartile range): 51.0 (46.0-56.0) vs. 53.0 (45.5-57.5) years, p > 0.05) and sex (70.5% men vs. 72.4% women). MS subjects had lower serum levels of myonectin than NMS subjects (1.08 (0.87-1.35) vs. 1.09 (0.93-4.05) ng·mL-1, p < 0.05). Multiple linear regression models adjusted for age, sex, fat mass index and lean mass index showed that serum myonectin was negatively correlated with the android/gynoid fat mass ratio (R2 = 0.48, p < 0.01), but not with the lipid profile, FFA, intramuscular lipid content or HOMA-IR. In conclusion, serum myonectin is lower in subjects with MS. Myonectin negatively correlates with a component relevant to the pathophysiology of MS, such as the android/gynoid fat mass ratio, but not with other components such as FFA, intramuscular fat or IR.

Cannabidiol improves muscular lipid profile by affecting the expression of fatty acid transporters and inhibiting de novo lipogenesis

Obesity is one of the principal public health concerns leading to disturbances in glucose and lipid metabolism, which is a risk factor for several chronic diseases, including insulin resistance, type 2 diabetes mellitus, and cardiovascular diseases. In recent years, it turned out that cannabidiol (CBD) is a potential therapeutic agent in the treatment of obesity and its complications. Therefore, in the present study, we used CBD therapy (intraperitoneal injections in a dose of 10 mg/kg of body mass for 14 days) in a rat model of obesity induced by a high-fat diet (HFD). Gas–liquid chromatography and Western blotting were applied in order to determine the intramuscular lipid content and total expression of selected proteins in the white and red gastrocnemius muscle, respectively. Based on fatty acid composition, we calculated de novo lipogenesis ratio (16:0/18:2n-6), desaturation ratio (18:1n-9/18:0), and elongation ratios (18:0/16:0, 20:0/18:0, 22:0/20:0 and 24:0/22:0), in the selected lipid fractions. Two-week CBD administration significantly reduced the intramuscular fatty acids (FAs) accumulation and inhibited de novo lipogenesis in different lipid pools (in the free fatty acid, diacylglycerol, and triacylglycerol fractions) in both muscle types, which coincided with a decrease in the expression of membrane fatty acid transporters (fatty acid translocase, membrane-associated fatty acid binding protein, and fatty acid transport proteins 1 and 4). Moreover, CBD application profoundly improved the elongation and desaturation ratios, which was in line with downregulated expression of enzymes from the family of elongases and desaturases regardless of the metabolism presented by the muscle type. To our knowledge, this study is the first that outlines the novel effects of CBD action on skeletal muscle with different types of metabolism (oxidative vs. glycolytic).

Transcriptome profile of skeletal muscle using different sources of dietary fatty acids in male pigs.

Pork is of great importance in world trade and represents the largest source of fatty acids in the human diet. Lipid sources such as soybean oil (SOY), canola (CO), and fish oil (FO) are used in pig diets and influence blood parameters and the ratio of deposited fatty acids. In this study, the main objective was to evaluate changes in gene expression in porcine skeletal muscle tissue resulting from the dietary oil sources and to identify metabolic pathways and biological process networks through RNA-Seq. The addition of FO in the diet of pigs led to intramuscular lipid with a higher FA profile composition of C20:5 n-3, C22:6 n-3, and SFA (C16:0 and C18:0). Blood parameters for the FO group showed lower cholesterol and HDL content compared with CO and SOY groups. Skeletal muscle transcriptome analyses revealed 65 differentially expressed genes (DEG, FDR 10%) between CO vs SOY, and 32 DEG for CO vs FO, and 531 DEG for SOY vs FO comparison. Several genes, including AZGP1, PDE3B, APOE, PLIN1, and LIPS, were found to be down-regulated in the diet of the SOY group compared to the FO group. The enrichment analysis revealed DEG involved in lipid metabolism, metabolic diseases, and inflammation between the oil groups, with specific gene functions in each group and altered blood parameters. The results provide mechanisms to help us understand the behavior of genes according to fatty acids.

Effect of FASN, SCD, and GH Genes on Carcass Fatness and Fatty Acid Composition of Intramuscular Lipids in F1 Holstein × Beef Breeds

To improve beef quality, a selection of specific breeds for crossbreeding, genotyping, and selection of specific candidate genes in breeding animals can be some of the solutions. The objective of this study was to determine the effects of FASN, SCD, and GH genes on carcass fatness and fatty acid (FA) composition of intramuscular lipids of crossbred Holstein × beef breeds (Simmental, Belgian Blue, Limousin, and Piemontese). The allelic and genotypic distribution of polymorphisms in the FASN, SCD, and GH genes was studied in 80 crossbreed animals. Genomic DNA was isolated from musculus longissimus dorsi, whose chemical composition was determined by near infrared transmittance spectrophotometry, while the fatty acid composition was determined by gas chromatography. DNA polymorphism was analyzed by restriction fragment length polymorphism analysis. The FASN (g. 17924A&gt;G) polymorphism was significantly associated with C19:1 n-9 and C24:1 n-9, whereas GH (g.2141C&gt;G) was significantly associated with C16:0 and C20:1 n-9. The SCD (g.8586C&gt;T) polymorphism was significantly associated with C16:0, C18:0, C20:0, C14:1 n-5, C16:1, C18:1, C18:2 n-6, C18:3 n-3, C20:2 n-6, and C20:4 n-6, and analyzed the sum and ratios of fatty acids. Sex had significant effect on carcass fatness and fatty acid composition. This study provided useful results for the above candidate genes and their association with some FA, supporting their influence as genes associated with fats and fatty acid composition in beef meat.

Intramuscular lipid utilization during exercise: a systematic review, meta-analysis, and meta-regression.

Intramuscular lipid (IMCL) utilization during exercise was controversial as numerous studies did not observe a decline in IMCL content post-exercise when assessed in muscle biopsies using biochemical techniques. Contemporary techniques including immunofluorescence microscopy and 1H-magnetic resonance spectroscopy (1H-MRS) offer advantages over biochemical techniques. The primary aim of this systematic review, meta-analysis, and meta-regression was to examine the net degradation of IMCL in response to an acute bout of cycling exercise in humans, as assessed with different analytical approaches. A secondary aim was to explore the factors influencing IMCL degradation including feeding status, exercise variables, and participant characteristics. A total of 44 studies met the inclusion criteria using biochemical, immunofluorescence, and 1H-MRS techniques. A meta-analysis was completed using a random effects model and percentage change in IMCL content calculated from the standardized mean difference. Cycling exercise resulted in a net degradation of IMCL regardless of technique (total effect -23.7%, 95% CI = -28.7 to -18.7%) and there was no difference when comparing fasted versus fed-state exercise (P > 0.05). IMCL degradation using immunofluorescence techniques detected larger effects in type I fibers compared with whole muscle using biochemical techniques (P = 0.003) and in type I fibers compared with type II fibers (P < 0.001). Although IMCL degradation was associated with exercise duration, V̇o2max, and BMI, none of these factors independently related to the change in IMCL content. These findings provide strong evidence that the analytical approach can influence the assessment of IMCL degradation in human skeletal muscle in response to exercise.

Identification and analysis of lncRNA, miRNA and mRNA related to subcutaneous and intramuscular fat in Laiwu pigs.

Long non-coding RNAs (lncRNAs) regulate adipocyte differentiation and metabolism, However, their function on subcutaneous and intramuscular adipose tissues in pigs is unclear. Intramuscular fat (IMF) is an important indicator for evaluating meat quality. Breeds with high IMF content are often accompanied by high subcutaneous fat (SCF), which severely affects the meat rate of pigs. It is of great significance for porcine breeding to study the mechanism of lncRNA related to adipogenesis and lipid metabolism. We identified differentially expressed lncRNAs, miRNAs and mRNAs in subcutaneous and intramuscular adipose tissues in three female Laiwu pigs by deep RNA-sequencing(|log2foldchange|≥1, P_value ≤ 0.05). The gene expression profiles of IMF and SCF in Laiwu pigs were comparatively analyzed by Bioinformatics methods to identify key lncRNAs, miRNAs, and mRNAs associated with lipid metabolism and adipogenesis. A total of 1209 lncRNAs (DElncRNAs), 286 miRNAs (DEmiRNAs), and 1597 mRNAs (DEgenes) were differentially expressed between two types of adipose. Among them, 17 DElncRNAs and 103 target genes play a role in the co-expression network, as well as 59 DElncRNAs, 44 DEmiRNAs, and 88 DEgenes involved in ceRNA network. In GO(Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis of DElncRNAs their target genes involved in many adipogenesis and lipid metabolism biological processes and signaling pathways, such as PPAR signaling pathway, Wnt signaling pathway, MAPK signaling pathway. By constructing co-expression and ceRNAs network we found that Wnt signaling pathway play a critical regulatory role in intramuscular adipogenesis and lipid accumulation in Laiwu pigs. TCONS_00006525, TCONS_00046551 and TCONS_00000528 may target WNT5A, WNT10B and FDZ3 in co-expression network, TCONS_00026517 and other lncRNAs regulate the expression of PPARG, RXRG and SCD in ceRNA network, and were involved in Wnt signaling pathway. This study provides a theoretical basis for further understanding the post-transcriptional regulation mechanism of meat quality formation, predicting and treating diseases caused by ectopic fat.

Intramuscular mitochondrial and lipid metabolic changes of rats after regular high-intensity interval training (HIIT) of different training periods.

High-intensity Interval Training (HIIT) is a time-efficient form of exercise and has gained popularity in recent years. However, at molecular level, the understanding about the effects of HIIT is not comprehensive, and even less is elucidated about HIIT of different training duration cycles, although different durations always lead to different post-training consequences. In this study, by training SD rats using HIIT protocols lasting for different training duration cycles, we investigated the adaptive response of intramuscular triglyceride abundance as well as mitochondrial and lipid metabolic changes after HIIT training (2, 4, 6, 8, and 10weeks). We selected 72h after the last session of training as the time point of sacrifice. The suppressed activation of the cAMP-PKA pathway indicates that skeletal muscle was in the recovery phase at this time point. Intramuscular triglyceride abundance was significantly elevated after 2, 4, and 10weeks of HIIT. However, the lipid metabolism-related proteins inconsistently changed in a chaotic trend (see Table 1). The expression levels of PGC1-α and COX IV decreased after 2 and 4weeks of training and raised after 6 and 8weeks of training. The expression level of citrate synthase (CS) decreased after 2, 4, 8, and 10weeks of training, and showed an upward trend after 6weeks of training. While the activity of CS decreased after 2 and 8weeks of training and showed an upward trend after 6weeks of HIIT. Given the abovementioned changing trends, we propose two speculations: (A) the damaged mitochondria oxidation capacity might be one of the causes of IMTG accumulation observed after 2 and 4weeks of HIIT. This phase might be similar to the condition of type 2 diabetes. (B) after 6-week HIIT, mitochondria function and biogenesis might be improved and the IMTG contents declined to baseline. This might be explained as: mitochondrial enhancement increased the capacity of lipid oxidation and then offset the increase in IMTG achieved during the first 4weeks. For HIIT Rat Modelling, if the aim is to observe HIIT-induced positive effects, caution should be exercised when considering 2 and 4weeks of training under our HIIT frame. Also, implementing six-week training is at least effective for mitochondrial enhancement when using similar HIIT frame of this study.

MiR-130b duplex (miR-130b-3p/miR-130b-5p) negatively regulates goat intramuscular preadipocyte lipid droplets accumulation by inhibiting Krüppel-like factor 3 expression.

Intramuscular lipid deposition is important for meat quality improvement. microRNAs and their target mRNAs provide a new approach for studying the mechanism of fat deposition. The present study aimed to investigate the effect of miR-130b duplex (miR-130b-5p, miR-130b-3p) and its target gene KLF3 in regulating goat intramuscular adipocyte differentiation. Goat intramuscular preadipocytes were isolated from 7-d-old male Jianzhou big-ear goats and identified by Oil red O staining after differentiation induction. miR-130b-5p and miR-130b-3p mimics or inhibitors and their corresponding controls were transfected into goat intramuscular preadipocytes, respectively, and differentiation was induced by 50μM oleic acid for 48 h. Oil red O and Bodipy staining indicated that both miR-130b-5p and miR-130b-3p can reduce lipid droplets accumulation and triglyceride (TG) content (P < 0.01). Differentiation markers C/EBPα, C/EBPβ, PPARγ, pref1, fatty acids synthesis markers ACC, FASN, DGAT1, DGAT2, AGPAT6, TIP47, GPAM, ADRP, AP2, SREBP1, and TG markers LPL, ATGL, HSL were assessed by qPCR. All the markers measured were downregulated by miR-130b-5p and miR-130b-3p analog (P < 0.01), suggesting that miR-130b inhibits goat intramuscular adipocyte adipogenic differentiation, fatty acids synthesis, and lipid lipolysis. To examine the mechanism of miR-130b duplex inhibition of lipid deposition, TargetScan, miRDB, and starBase were used to predict the potential targets, KLF3 was found to be the only one intersection. Furthermore, the 3'UTR of KLF3 was cloned, qPCR analysis and dual luciferase activity assay showed that both miR-130b-5p and miR-130b-3p could directly regulate KLF3 expression (P < 0.01). In addition, overexpression and interference of KLF3 were conducted, it was found that KLF3 positively regulated lipid droplets accumulation by Oil red O, Bodipy staining, and TG content detection (P < 0.01). Quantitative PCR result indicated that KLF3 overexpression promoted lipid droplets accumulation relative genes C/EBPβ, PPARγ, pref1, ACC, FASN, DGAT1, DGAT2, AGPAT6, TIP47, GPAM, ADRP, SREBP1, LPL, and ATGL expression (P < 0.01). Downregulation of KLF3 inhibited the expression of genes such as C/EBPα, C/EBPβ, PPARγ, pref1, TIP47, GPAM, ADRP, AP2, LPL, and ATGL expression (P < 0.01). Taken together, these results indicate that miR-130b duplex could directly inhibit KLF3 expression, then attenuated adipogenic and TG synthesis genes expression, thus leading to its anti-adipogenic effect.

Characteristics, lipogenic enzyme activity, and fatty acid composition of muscles in the Iberian pig: Effects of protein restriction and free-range feeding

In Iberian pigs, protein restriction during the final fattening period does not affect productive parameters and carcase fatness but increases the intramuscular lipid content. The aim of this study was to investigate the effects of a low-crude protein diet on the muscle characteristics, metabolism, lipogenic enzyme activity, and fatty acid composition of Iberian pigs fed under confinement and free-range conditions. Twenty-four castrated male Iberian pigs with an average initial body weight (BW) of 116.0 kg were divided into three groups (n = 8); the first and second groups were fed isoenergetic (4100 kcal ME/kg dry matter) concentrated diets with standard protein (12.8%) (SP) and low protein (6.6%) (LP) contents, respectively, under outdoor confinement; the third group was fed on natural resources (acorn and grass) under free-range conditions (FR). The pigs were slaughtered at an average BW of 174.2 kg. Compared with pigs fed the SP diet, LP and FR pigs showed significantly high intramuscular fat (IMF) contents and low muscle and fiber areas. In the muscle, the activities of glucose-6-phosphate dehydrogenase (G6PDH) and malic enzyme (ME) were not affected by diet, but a slight increase in ME activity was observed in SP pigs compared to that in LP and FR pigs when the results were expressed as per g lipid. Plasma concentrations of glucose, creatinine and protein were not affected by the experimental diets, but plasma urea concentration was significantly lower in FR than in SP pigs, with intermediate values in LP. The effect of protein reduction in diets was more marked on neutral than on polar lipid contents, and higher saturated fatty acid and lower polyunsaturated fatty acid proportions were observed in LP pigs than in SP and FR pigs. So, a reduction in protein levels in the diets of Iberian pigs during the fattening period affected muscle lipid composition, despite the slight effect observed on lipogenic enzyme activity. Furthermore, the longissimus lumborum and serratus ventralis muscles showed similar responses to diets with different protein levels but differed in their chemical compositions and metabolic activities, which suggested that serratus ventralis, with a lower commercial value, could be adequate as the muscle of choice for analysis of meat composition and quality in the Iberian pig.

The effects of feeding benzoic acid and/or active dry yeast (Saccharomyces cerevisiae) on fatty acid composition, sensory attributes, and retail shelf-life of beef longissimus thoracis.

Fifty-nine Angus-cross steers (492 ± SD 36 kg) were arranged in a randomized complete block design and assigned to the following dietary treatments for the final 106 days of the finishing phase: no supplementation (CON), 0.5% benzoic acid (ACD), 3 g/steer/d active dry Saccharomyces cerevisiae (YST), or both [0.5% benzoic acid and 3 g/steer/d S. cerevisiae (AY)]. Steers were slaughtered at a commercial facility where longissimus thoracis (IMPS #107 Beef Rib) samples were retrieved and evaluated for fatty acid composition, sensory attributes, and shelf-life during a simulated retail display period. Data (N = 57) were analyzed using dietary treatment as a fixed effect, blocking weight at the beginning of the study as a random effect, and steer as the experimental unit. Muscle pH and proximate composition (moisture and intramuscular lipid) for longissimus samples were not different (P ≥ 0.39) among dietary treatments. Most fatty acid profile values and calculations were not different among dietary treatments (P ≥ 0.10); however, the n-6:n-3 ratio differed (P = 0.01), with ACD samples having lower n-6:n-3 compared with CON and YST samples while AY samples were intermediate and not different from other dietary treatments. The trained sensory panel did not detect differences among dietary treatments (P ≥ 0.23) for juiciness, beef flavor intensity, or off-flavor intensity; however, they did score AY samples as chewier than ACD samples with CON and YST samples intermediate and not different from other dietary treatments. Yet, tenderness was not different when scored by trained panelists (P = 0.10) or measured instrumentally (P = 0.21). Total color change tended to differ (P = 0.09) during the 12-d simulated retail display period with AY samples experiencing less color change compared with YST samples, while CON and ACD samples were intermediate and not different from other dietary treatments. Lipid oxidation (as measured with TBARS) tended to differ (P = 0.08) following the 12-d simulated retail display period with ACD and AY samples experiencing lower levels of oxidation compared with CON, while YST samples were intermediate and not different from other dietary treatments. Overall, these results suggest there were no negative impacts on meat quality when finishing steers were supplemented with either benzoic acid or S. cerevisiae, and there may even be advantages for fatty acid composition and oxidative stability when steers were supplemented with benzoic acid.

Altered intramuscular network of lipid droplets and mitochondria in type 2 diabetes.

Excessive storage of lipid droplets (LDs) in skeletal muscles is a hallmark of type 2 diabetes. However, LD morphology displays a high degree of subcellular heterogeneity and varies between single muscle fibers, which impedes the current understanding of lipid-induced insulin resistance. Using quantitative transmission electron microscopy (TEM), we conducted a comprehensive single-fiber morphological analysis to investigate the intramuscular network of LDs and mitochondria, and the effects of 8 wk of high-intensity interval training (HIIT) targeting major muscle groups, in patients with type 2 diabetes and nondiabetic obese and lean controls. We found that excessive storage of intramuscular lipids in patients with type 2 diabetes was exclusively explained by extremely large LDs situated in distinct muscle fibers with a location-specific deficiency in subsarcolemmal mitochondria. After HIIT, this intramuscular deficiency was improved by a remodeling of LD size and subcellular distribution and mitochondrial content. Analysis of LD morphology further revealed that individual organelles were better described as ellipsoids than spheres. Moreover, physical contact between LD and mitochondrial membranes indicated a dysfunctional interplay between organelles in the diabetic state. Taken together, type 2 diabetes should be recognized as a metabolic disease with high cellular heterogeneity in intramuscular lipid storage, underlining the relevance of single-cell technologies in clinical research. Furthermore, HIIT changed intramuscular LD storage toward nondiabetic characteristics.

Assessment of the chemical characteristics and nutritional quality of meat from broiler chicken fed black soldier fly (Hermetia illucens) larvae meal

In this study, we aim to evaluate the chemical characteristics, and nutritional quality of raw meat from broiler chicken fed a black soldier fly larvae meal. Three hundred twenty female broiler chicks were divided into four dietary treatments (8 replicates/treatments). Birds were fed maggot meal at 0%, 4%, 8%, and 12%. At 42 days of age, 16 birds/treatment were randomly selected and slaughtered. The chemical characteristics and nutritional quality of the meat were assessed. Abdominal fat, intramuscular lipid levels, and cholesterol levels increased (p < 0.05) in chicken-fed larvae meal. The latter had a higher level of mono-unsaturated and polyunsaturated fatty acids but a lower level of omega 3 (ω3) compared to the control. The atherogenicity index (AI) and the thrombogenicity index (TI) decreased with maggot meal incorporation. The unsaturation index was better at 4% and 8% maggot meal. Chickens fed with 8% maggot meal would present less risk for cardiovascular health.

Exercise training attenuates skeletal muscle fat infiltration and improves insulin pathway of patients with immune-mediated necrotizing myopathies and dermatomyositis.

This study aims to evaluate the effects of exercise training on intramuscular lipid content and genes related to insulin pathway in patients with systemic autoimmune myopathies (SAMs). Between January 2016 and May 2019, a total of seven patients with dermatomyositis (DM; 3 males, 4 females; mean age: 49.8±2.3 years; range, 43 to 54 years), six with immune mediated necrotizing myopathy (IMNM; 3 males, 3 females; mean age: 58.5±10.6 years; range, 46 to 74 years), and 10 control individuals (CTRL group; 4 males, 6 females; mean age: 48.7±3.9 years; range, 41 to 56 years) were included. The muscle biopsy before and after the intervention was performed to evaluate the intramuscular lipid content. Patients underwent a combined exercise training program for 12 weeks. Skeletal muscle gene expression was analyzed and the DM versus CTRL group, DM pre- and post-, and IMNM pre- and post-intervention were compared. The DM group had a higher intramuscular lipid content in type II muscle fibers compared to the CTRL group. After the intervention, there was a reduction of lipid content in type I and II fibers in DM and IMNM group. The CTRL group showed a significantly higher expression of genes related to insulin and lipid oxidation pathways (AMPKβ2, AS160, INSR, PGC1-α, PI3K, and RAB14) compared to the DM group. After exercise training, there was an increase gene expression related to insulin pathway and lipid oxidation in DM group (AMPKβ2, AS160, INSR, PGC1-α, PI3K, and RAB14) and in IMNM group (AKT2, AMPKβ2, RAB10, RAB14, and PGC1-α). Exercise training attenuated the amount of fat in type I and II muscle fibers in patients with DM and IMNM and increased gene expression related to insulin pathways and lipid oxidation in DM and IMNM. These results suggest that exercise training can improve the quality and metabolic functions of skeletal muscle in these diseases.

Effect of Lipids in Yak Muscle under Different Feeding Systems on Meat Quality Based on Untargeted Lipidomics.

Simple SummaryWith the development of living standards, consumers are paying more and more attention to meat quality and flavor. When consumers choose meat, they directly pay attention to meat quality and flavor, so the meat quality and flavor directly decide meat price and sales volume. Better meat quality and flavor are the crucial factors that increase the additional value of meat. Because of its special nutritional value and taste, yak meat is popular with consumers. The intramuscular lipids can greatly affect the meat quality and flavor, but there is no report on the effect of lipids in yak muscle on the meat quality and flavor. In this study, we studied the characterization of lipids in yak muscle under different feeding systems and further explored the key lipids affecting yak meat quality and flavor. This study can provide new insight into the improvement of yak meat quality and flavor.The effect of lipids on yak meat quality and volatile flavor compounds in yak meat under graze feeding (GF) and stall feeding (SF) was explored using untargeted lipidomics based on liquid chromatography–mass spectrometry (LC-MS) in this study. First, the volatile flavor compounds in longissimus dorsi (LD) of SF and GF yaks were detected by gas chromatography–mass spectrometry (GC-MS). In total 49 and 39 volatile flavor substances were detected in the LD of GF and SF yaks, respectively. The contents of pelargonic aldehyde, 3-hydroxy-2-butanone and 1-octen-3-ol in the LD of both GF and SF yaks were the highest among all detected volatile flavor compounds, and the leading volatile flavor substances in yak LD were aldehydes, alcohols and ketones. In total, 596 lipids were simultaneously identified in the LD of SF and GF yaks, and the leading lipids in the LD of both GF and SF yaks were sphingolipids (SPs), glycerolipids (GLs) and glycerophospholipids (GPs). Seventy-five significantly different lipids (SDLs) between GF and SF yaks were identified in the LD. The high content of TG(16:1/18:1/18:1), TG(16:0/17:1/18:1) and TG(16:0/16:1/18:1), PE(18:0/22:4) and PC(18:2/18:0) can improve the a* (redness) and tenderness of yak muscle. The changes in volatile flavor compounds in yak muscle were mainly caused by TG(18:1/18:1/18:2), TG(18:0/18:1/18:1), TG(16:0/17:1/18:1), TG(16:0/16:1/18:1), PC(18:2/18:0), TG(16:1/18:1/18:1), PI(18:0/20:4), TG(16:1/16:1-/18:1) and TG(17:0/18:1/18:1). The above results provide a theoretical basis for improving yak meat quality from the perspective of intramuscular lipids.

Empagliflozin Preserves Skeletal Muscle Function in a HFpEF Rat Model.

Besides structural alterations in the myocardium, heart failure with preserved ejection fraction (HFpEF) is also associated with molecular and physiological alterations of the peripheral skeletal muscles (SKM) contributing to exercise intolerance often seen in HFpEF patients. Recently, the use of Sodium-Glucose-Transporter 2 inhibitors (SGLT2i) in clinical studies provided evidence for a significant reduction in the combined risk of cardiovascular death or hospitalization for HFpEF. The present study aimed to further elucidate the impact of Empagliflozin (Empa) on: (1) SKM function and metabolism and (2) mitochondrial function in an established HFpEF rat model. At the age of 24 weeks, obese ZSF1 rats were randomized either receiving standard care or Empa in the drinking water. ZSF1 lean animals served as healthy controls. After 8 weeks of treatment, echocardiography and SKM contractility were performed. Mitochondrial function was assessed in saponin skinned fibers and SKM tissue was snap frozen for molecular analyses. HFpEF was evident in the obese animals when compared to lean—increased E/é and preserved left ventricular ejection fraction. Empa treatment significantly improved E/é and resulted in improved SKM contractility with reduced intramuscular lipid content. Better mitochondrial function (mainly in complex IV) with only minor modulation of atrophy-related proteins was seen after Empa treatment. The results clearly documented a beneficial effect of Empa on SKM function in the present HFpEF model. These effects were accompanied by positive effects on mitochondrial function possibly modulating SKM function.

Effect Of Electromyostimulation Training On Intramuscular Fat Accumulation And Blood Lipids In Older Adults

PURPOSE: Aging induces muscle atrophy, decline of muscular metabolism, and excessive intramuscular fat accumulation. Aerobic and anerobic training enhance glycolytic or oxidative enzymes, and improve muscle size in older adults. However, these trainings are assumed difficult for older adult with disfunction of lower leg. Electromyostimulation (EMS) is commonly used in clinical settings to improve the muscular functions in older adults. The purpose of this study was to examine the effects of EMS training on intramuscular fat content and blood lipids of quadriceps femoris muscles in older adults. METHODS: Nineteen physically active, non-obese older men and women (mean age 71.5 ± 5.4 years) were performed EMS training of the quadriceps femoris muscle for 12 weeks (3 times/week). Single EMS session consisted of 7 s contraction/relaxation cycle for 30 min. Intramuscular fat content was estimated by echo intensity of vastus lateralis using ultrasonography. Free fatty acids (FFA) were measured from blood samples. Echo intensity and FFA were measured before and after EMS training. To determine acute effect of single EMS session, FFA was measured before and after the EMS session. RESULTS: EMS training did not significant change echo intensity (pre 63.7 ± 11.1 a.u.; post 62.4 ± 9.0 a.u.) and FFA (pre 523.3 ± 187.0 μEq/L; post 503.5 ± 223.0 μEq/L). Regarding acute effect on blood lipid, single EMS session increased FFA (pre 523.3 ± 187.0 μEq/L; post 606.9 ± 185.2μEq/L, p < 0.01). CONCLUSIONS: Acute effect of EMS session on blood lipids was obtained, but EMS training intervention for 12 weeks did not improve intramuscular fat content of quadriceps femoris muscle and blood lipids. Supported by a Grant in Aid (KAKENHI 18 K17764).

Effect of Intradialytic Oral Nutritional Supplementation with or without Exercise Improves Muscle Mass Quality and Physical Function in Hemodialysis Patients: A Pilot Study.

Background: Oral nutritional supplementation (ONS) with or without exercise (EX) could improve muscle mass (MM) in chronic kidney disease. Methods: Patients were randomized into two groups: (1) ONS and (2) ONS + EX. Thigh muscle area (cm2) and intramuscular lipid content via attenuation were evaluated at baseline and 6 months with computed tomography (CT) to measure MM quantity and quality. Physical function was measured by six-minute walk test (6 MWT), gait speed, handgrip strength (HGS), and Time Up and Go test (TUG) at baseline and 3 and 6 months. Results: The ONS group (n= 14) showed statistically significant improvement in gait speed and HGS; ONS + EX group (n = 10) showed differences in gait speed, in 6 MWT, and HGS. In the ANOVA (3 times × 2 groups), no differences were observed between groups. Greater effect sizes in favor to ONS + EX group were observed in the 6 MWT (d = 1.02) and TUG test (d = 0.63). Muscle quality at six months revealed a significant trend in favor of the EX-group (p = 0.054). Conclusions: Both groups had improved physical function, and greater effect sizes were seen in the ONS + EX group for the 6 MWT and TUG test. Neither MM quantity or quality was improved in either group.

An Investigation on the Influence of Various Biochemical Tenderness Factors on Eight Different Bovine Muscles

This study’s objective was to understand the relationships between biochemical tenderness components andobjective/sensory measure of tenderness of 8 muscles from beef carcasses. Longissimus thoracis (LT), pectoralis profundus (PP), supraspinatus, triceps brachii (TB), gluteus medius (GM), rectus abdominus (RA), rectus femoris, and semitendinosus (ST) were collected from 10 USDA upper 2/3 Choice beef carcasses and assigned to a 2- or 21-d aging period (n=160). Troponin-T degradation, desmin degradation, sarcomere length, collagen content, mature collagen crosslink density, intramuscular lipid content, pH, Warner-Bratzler Shear Force (WBSF), and trained sensory panel analyses were measured. A Pearson correlation analysis was conducted to determine the relationship between each tenderness contributor measured in this study with WBSF or the overall tenderness evaluated by the trained panelist for each of the 8 muscles.In addition, multivariate regression models were constructed to confirm this relationship. The results showed that muscle anatomical locations and physiological functions driven by muscle fiber types may explain some of the biochemical/tenderness differences found in this study. The correlation analysis showed that each muscle had a specific tenderness factor(s)that contributed to the overall tenderness. For instance, tenderness for LT, TB, GM, RA, and ST may be influenced more by proteolytic degradation, while the collagen characteristics may primarily influence tenderness for PP. Also, lipid content has a significant influence on GM tenderness. Finally, the multivariate regression model showed that almost all of the biochemical measurements conducted in this study contributed to overall tenderness to some degree across muscles.Increasing the knowledge base on the various tenderness components’ level of contribution will allow end-users to develop specific tenderness management strategies to ensure consistent tenderness in beef products.

Dietary Valine/Isoleucine Ratio Impact Carcass Characteristics, Meat Edible Quality and Nutritional Values in Finishing Crossbred Duroc × Landrace × Yorkshire Pigs With Different Slaughter Weights.

The aim of this study was to investigate effects of dietary ratio of valine to isoleucine [R(V/I)] on carcass characteristics and meat quality of finishing pigs and whether slaughter weight influence the effect. We carried out a 2 × 3 factorial trial with two slaughter weight (105 vs. 130 kg) and three R(V/I) (0.58, 1.23, and 2.60 at 75–100 kg body weight, and 0.70, 1.24, and 2.39 at 100–135 kg body weight for L-, N- and H-R (V/I), respectively). Data show that increasing slaughter weight significantly increased meat color (a*45 min and b*45 min), drip loss and shear force (P < 0.05). Meanwhile, increasing slaughter weight reduced sarcomere length, the proportion of protein-bound water, and most kinds of muscular total amino acid contents except for tryptophan and arginine, while increased contents of muscular free lysine, tryptophan, leucine, isoleucine, valine, alanine, and arginine in the M. longissimus thoracis (P < 0.05). Health lipid indices based on fatty acid composition of intramuscular lipid were improved as the slaughter weight increased (P < 0.05). Notably, pigs received N-R (V/I) diet improved carcass traits in terms of thinner backfat thickness and higher fat-free lean index, as well as increased meat flavor-contributing amino acids at the cost of reduced intramuscular fat content and increased shear force of cooked meat compared with the pigs fed L-R (V/I) and H-R(V/I) diets (P < 0.05). H-R (V/I) diet decreased ultimate pH value and sarcomere length of the skeletal muscle but increased the proportion of free water (T23), consequently, increased drip loss and cooking loss of fresh meat in pigs (P < 0.05). In conclusion, both slaughter weight and dietary ratio of valine to isoleucine exerted significant impacts on carcass characteristics, meat quality and nutrition values. In particular, carcass traits and meat color of lighter pigs were more susceptible to the influence of dietary R (V/I) relative to heavier pigs.

Integration analyses of structural variations and differential gene expression associated with beef fatty acid profile in Nellore cattle.

This study aimed to integrate analyses of structural variations and differentially expressed genes (DEGs) associated with the beef fatty acid (FA) profile in Nellore cattle. Copy numbers variation (CNV) detection was performed using the penncnv algorithm and CNVRuler software in 3794 genotyped animals through the High-Density Bovine BeadChip. In order to perform the genomic wide association study (GWAS), a total of 963 genotyped animals were selected to obtain the intramuscular lipid concentration and quantify the beef FA profile. A total of 48 animals belonging to the same farm and management lot were extracted from the 963 genotyped and phenotyped animals to carry out the transcriptomic and differentially expressed gene analyses. The GWAS with extreme groups of FA profiles was performed using a logistic model. A total of 43, 42, 66 and 35 significant CNV regions (p < 0.05) for saturated, monounsaturated, polyunsaturated and omega 3 and 6 fatty acids were identified respectively. The paired-end sequencing of 48 samples was performed using the Illumina HiSeq2500 platform. Real-time quantitative PCR was used to validate the DEGs identified by RNA-seq analysis. The results showed several DEGs associated with the FA profile of Longissimus thoracis, such as BSCL2 and SAMD8. Enriched terms as the cellular response to corticosteroid (GO:0071384) and glucocorticoid stimulus (GO:0071385) could be highlighted. The identification of structural variations harboring candidate genes for beef FA must contribute to the elucidation of the genetic basis that determines the beef FA composition of intramuscular fat in Nellore cattle. Our results will contribute to the identification of potential biomarkers for complex phenotypes, such as the FA profile, to improve the reliability of the genomic predictions including pre-selected variants using differentiated weighting in the genomic models.