Effects of lycopene on skeletal muscle-fiber type and high-fat diet-induced oxidative stress

Luteolin alleviates muscle atrophy, mitochondrial dysfunction and abnormal FNDC5 expression in high fat diet-induced obese rats and palmitic acid-treated C2C12 myotubes

Obesity is associated with a series of skeletal muscle impairments and dysfunctions, which are characterized by metabolic disturbances and muscle atrophy. Luteolin is a phenolic phytochemical with broad pharmacological activities. The present study aimed to evaluate the protective effects of Luteolin on muscle function and explore the potential mechanisms in high-fat diet (HFD)-induced obese rats and palmitic acid (PA)-treated C2C12 myotubes. Male Sprague-Dawley (SD) rats were fed with a control diet or HFD and orally administrated 0.5% sodium carboxymethyl cellulose (vehicle) or Luteolin (25, 50 and 100 mg/kg, respectively) for 12 weeks. The results showed that Luteolin ameliorated HFD-induced body weight gain, glucose intolerance and hyperlipidemia. Luteolin also alleviated muscle atrophy, decreased ectopic lipid deposition and prompted muscle-fiber-type conversion in the skeletal muscle. Meanwhile, we observed an evident improvement in mitochondrial quality control and respiratory capacity, accompanied by reduced oxidative stress. Mechanistic studies indicated that AMPK/SIRT1/PGC-1α signaling pathway plays a key role in the protective effects of Luteolin on skeletal muscle in the obese states, which was further verified by using specific inhibitors of AMPK and SIRT1. Moreover, the mRNA expression levels of markers in brown adipocyte formation were significantly up-regulated post Luteolin supplementation in different adipose depots. Taken together, these results revealed that Luteolin supplementation might be a promising strategy to prevent obesity-induced loss of mass and biological dysfunctions of skeletal muscle.

Effects of lycopene on the growth performance, meat quality, cecal metagenome, and hepatic untargeted metabolome in heat stressed broilers

The occurrence of heat stress in poultry houses is inevitable and leads to oxidative stress in the birds. Lycopene, a natural hydrocarbon carotenoid, possesses potent antioxidant properties. This study aimed to investigate the impact of lycopene on growth performance, meat quality, cecal microflora, and liver metabolome in broilers subjected to heat stress. A total of 480 yellow feather broilers were randomly allocated into 4 treatment groups: birds fed standard diet (Con), birds fed standard diet and supplemented with lycopene (Lyc), birds fed standard diet and subjected to heat stress (Hs), and birds fed with lycopene and subjected to heat stress (Hs-Lyc). As compared with the normal temperature groups, Hs decreased the average daily gain (ADG) of birds during d 1 to 28, lowered the pH value either in breast meat or thigh meat, increased the L* value of breast meat, and decreased the a* value of thigh meat. In comparison with non-Lyc feeding birds, Lyc supplement elevated the ADG during d 1 to 56, increased the pH of breast meat, decrease the L* and b* values of thigh meat, simultaneously increase the a* value of thigh meat. The L* of breast meat and pH of thigh meat exhibited significant differences under Hs-Lyc treatment. Lyc-treated birds exhibited higher elasticity, gumminess, and resilience in breast meat than those in non-Lyc feeding birds. The cecal metagenome analysis indicated that Hs-Lyc treatment increased the abundance of Phocaeicola salanitronis and Prevotella sp.CAG:1058, Bacteroides sp.An269, and Bacteroides sp.An19 at the species level compared with other treatments. The hepatic untargeted metabolome analysis showed that administration of Lyc upregulated 20 metabolites and downregulated 60 metabolites compared to the Con birds. Futhermore, the Hs-Lyc treatment upregulated 34 metabolites and downregulated 45 metabolites compared to the Hs birds. The correlation between the metagenome and metabolome showed that Lyc supplementation induced significant alterations in the citrate cycle, metabolism of butanoate, glycolysis/gluconeogenesis, glyoxylate and dicarboxylate, alanine, aspartate, and glutamate compared with standard supplement. In contrast, Hs-Lyc treatment induced alterations in the citrate cycle, metabolism of pyruvate, glyoxylate, and dicarboxylate, glycolysis/gluconeogenesis, arginine, proline, alanine, aspartate, and glutamate compared with the standard supplement of heat-challenged broilers. In summary, dietary Lyc supplementation promoted the growth performance, changed the meat quality, modulated the cecal metagenome and hepatic metabolome in heat-stressed broilers.

Tangeretin Enhances Muscle Endurance and Aerobic Metabolism in Mice via Targeting AdipoR1 to Increase Oxidative Myofibers

Slow oxidative myofibers play an important role in improving muscle endurance performance and maintaining body energy homeostasis. However, the targets and means to regulate slow oxidative myofibers proportion remain unknown. Here, we show that tangeretin (TG), a natural polymethoxylated flavone, significantly activates slow oxidative myofibers-related gene expression and increases type I myofibers proportion, resulting in improved endurance performance and aerobic metabolism in mice. Proteomics, molecular dynamics, cellular thermal shift assay (CETSA) and drug affinity responsive target stability (DARTS) investigations revealed that TG can directly bind to adiponectin receptor 1 (AdipoR1). Using AdipoR1-knockdown C2C12 cells and muscle-specific AdipoR1-knockout mice, we found that the positive effect of TG on regulating slow oxidative myofiber related markers expression is mediated by AdipoR1 and its downstream AMPK/PGC-1α pathway. Together, our data uncover TG as a natural compound that regulates the identity of slow oxidative myofibers via targeting the AdipoR1 signaling pathway. These findings further unveil the new function of TG in increasing the proportion of slow oxidative myofibers and enhancing skeletal muscle performance.

How soon do metabolic alterations and oxidative distress precede the reduction of muscle mass and strength in Wistar rats in aging process?

Here we investigate metabolic changes, the antioxidant system and the accumulation of oxidative damage in muscles with different fiber types during the aging process in Wistar rats and try to map how sooner the changes occur. To do so, 30 male Wistar rats were submitted to behavioral evaluation to determine voluntary strength in the 11, 15, and 19 month old rats, measuring the energy metabolism, antioxidant system, oxidative damage and structure in the soleus and extensor digitorum longus muscles. We detected structural and metabolic changes in both muscles, especially in the EDL of 15 month old rats and in the soleus of 19 month old rats. In the 15 month old rats, there was a reduction in the cross-sectional area of the fibers, and a reduction in the proportion of type I fibers, accompanied by an increase in fiber density and the amount of type IIA fibers. This change in the fiber profile was followed by an increase in the activity of anaerobic metabolism enzymes, suggesting a reduction in the oxidative capacity of the muscle. In addition, there was an increase in the rate of lipid peroxidation, accompanied by a reduced antioxidant capacity. In the 19 month old rats, these disturbances got stronger. In summary, the present study demonstrated that before functional disturbances, there was an accumulation of oxidative damage and structural changes in the skeletal muscle beginning at 15 months old in the EDL and the soleus only in the biochemical parameters. Therefore, the metabolic alterations occurred at 15 months old and not before.

Translatomics reveals the role of dietary calcium addition in regulating muscle fat deposition in pigs

Intramuscular fat (IMF) in pork holds significant importance for economic performance within the pig industry and dietary calcium supplementation enhances the accumulation of intramuscular fat. Additionally, calcium ions inhibit translation and reduce protein synthesis. However, the mechanism by which calcium regulates IMF deposition in muscle through translation remains largely unknown. In this study, we compared the ribosome profiles of the longissimus dorsi muscles of Duroc × Landrace × Large white pigs from the normal calcium (NC) group or calcium supplement (HC) group by Ribo-seq, and RNA-seq. By integrating multiple-omics analysis, we further discovered 437 genes that were transcriptionally unchanged but translationally altered and these genes were significantly enriched in the oxidative phosphorylation signaling pathway. Furthermore, experimental data showed that inhibiting the expression of COX10 and mtND4L increased triglyceride accumulation in C2C12 cells, providing new targets for intramuscular fat deposition. Finally, this work links dietary calcium, translation regulation and IMF deposition, providing a new strategy for both meat quality and economic performance within the pig industry.

6-Gingerol alleviates ectopic lipid deposition in skeletal muscle by regulating CD36 translocation and mitochondrial function

Ectopic lipid deposition (ELD) and mitochondrial dysfunction are common causes of metabolic disorders in humans. Consuming too much fructose can result in mitochondrial dysfunction and metabolic disorders. 6-Gingerol, the main component of ginger (Zingiber officinale Roscoe), has been proven to alleviate metabolic disorders. This study seeks to examine the effects of 6-gingerol on metabolic disorders caused by fructose and uncover the underlying molecular mechanisms. In this study, the results showed that 6-Gingerol ameliorated high-fructose-induced metabolic disorders. Moreover, it inhibited CD36 membrane translocation, increased CD36 expression in the mitochondria, and decreased the O-GlcNAc modification of CD36 and OGT expression in vitro and vivo. In addition, 6-Gingerol enhanced the performance of mitochondria in the skeletal muscle and boosted the respiratory capability of L6 myotubes. This study provides a theoretical basis and new insights for the development of lipid-lowering drugs in clinical practice.

Lycopene Promotes Osteogenesis and Reduces Adipogenesis through Regulating FoxO1/PPARγ Signaling in Ovariectomized Rats and Bone Marrow Mesenchymal Stem Cells

Recent interest in preventing the development of osteoporosis has focused on the regulation of redox homeostasis. However, the action of lycopene (LYC), a strong natural antioxidant compound, on osteoporotic bone loss remains largely unknown. Here, we show that oral administration of LYC to OVX rats for 12 weeks reduced body weight gain, improved lipid metabolism, and preserved bone quality. In addition, LYC treatment inhibited ROS overgeneration in serum and bone marrow in OVX rats, and in BMSCs upon H2O2 stimulation, leading to inhibiting adipogenesis and promoting osteogenesis during bone remodeling. At the molecular level, LYC improved bone quality via an increase in the expressions of FoxO1 and Runx2 and a decrease in the expressions of PPARγ and C/EBPα in OVX rats and BMSCs. Collectively, these findings suggest that LYC attenuates osteoporotic bone loss through promoting osteogenesis and inhibiting adipogenesis via regulation of the FoxO1/PPARγ pathway driven by oxidative stress, presenting a novel strategy for osteoporosis management.

Dietary supplementation with Lacticaseibacillus rhamnosus IDCC3201 alleviates sarcopenia by modulating the gut microbiota and metabolites in dexamethasone-induced models

Probiotics can exert direct or indirect influences on various aspects of health claims by altering the composition of the gut microbiome and producing bioactive metabolites. The aim of this study was to examine the effect of Lacticaseibacillus rhamnosus IDCC3201 on skeletal muscle atrophy in dexamethasone-induced C2C12 cells and a mouse animal model. Dexamethasone treatment significantly reduced C2C12 muscle cell viability, myotube diameter, and levels of muscle atrophic markers (Atrogin-1 and MuRF-1). These effects were alleviated by conditioned media (CM) and cell extract (EX) derived from L. rhamnosus IDCC3201. In addition, we assessed the in vivo therapeutic effect of L. rhamnosus IDCC3201 in a mouse model of dexamethasone (DEX)-induced muscle atrophy. Supplementation with IDCC3201 resulted in significant enhancements in body composition, particularly in lean mass, muscle strength, and myofibril size, in DEX-induced muscle atrophy mice. In comparison to the DEX-treatment group, the normal and DEX + L. rhamnosus IDCC3201 groups showed a higher transcriptional level of myosin heavy chain family genes (MHC1, MHC1b, MHC2A, 2bB, and 2X) and a reduction in atrophic muscle makers. These analyses revealed that L. rhamnosus IDCC3201 supplementation led to increased production of branched-chain amino acids (BCAAs) and improved the Allobaculum genus within the gut microbiota of muscle atrophy-induced groups. Taken together, our findings suggest that L. rhamnosus IDCC3201 represents a promising dietary supplement with the potential to alleviate sarcopenia by modulating the gut microbiome and metabolites.

Exercise couples mitochondrial function with skeletal muscle fiber type via ROS-mediated epigenetic modification

Skeletal muscle is a heterogeneous tissue composed of different types of muscle fibers, demonstrating substantial plasticity. Physiological or pathological stimuli can induce transitions in muscle fiber types. However, the precise regulatory mechanisms behind these transitions remains unclear. This paper reviews the classification and characteristics of muscle fibers, along with the classical mechanisms of muscle fiber type transitions. Additionally, the role of exercise-induced muscle fiber type transitions in disease intervention is reviewed. Epigenetic pathways mediate cellular adaptations and thus represent potential targets for regulating muscle fiber type transitions. This paper focuses on the mechanisms by which epigenetic modifications couple mitochondrial function and contraction characteristics. Reactive Oxygen Species (ROS) are critical signaling regulators for the health-promoting effects of exercise. Finally, we discuss the role of exercise-induced ROS in regulating epigenetic modifications and the transition of muscle fiber types.

Gromwell ameliorates glucocorticoid-induced muscle atrophy through the regulation of Akt/mTOR pathway

BACKGROUND

Muscle atrophy is characterized by decreased muscle mass, function, and strength. Synthetic glucocorticoids, including dexamethasone (Dexa), are commonly used to treat autoimmune diseases. However, prolonged exposure of Dexa with high dose exerts severe side effects, including muscle atrophy. The purpose of this study was to investigate whether Gromwell root extract (GW) can prevent Dexa-induced muscle atrophy in C2C12 cells and mice and to characterize the composition of GW to identify bioactive compounds.

METHODS

For in vitro experiments, GW (0.5 and 1 µg/mL) or lithospermic acid (LA, 5 and 10 µM) was added to C2C12 myotubes on day 4 of differentiation and incubated for 24 h, along with 50 µM Dexa. For in vivo experiment, four-week-old male C57BL/6 mice were randomly divided into the four following groups (n = 7/group): Con group, Dexa group, GW0.1 group, and GW0.2 group. Mice were fed experimental diets of AIN-93 M with or without 0.1 or 0.2% GW for 4 weeks. Subsequently, muscle atrophy was induced by administering an intraperitoneal injection of Dexa at a dose of 15 mg/kg/day for 38 days, in conjunction with dietary intake.

RESULTS

In Dexa-induced myotube atrophy, treatment with GW increased myotube diameter, reduced the expression of muscle atrophy markers, and enhanced the expression of myosin heavy chain (MHC) isoforms in C2C12 cells. Supplementation with the GW improved muscle function and performance in mice with Dexa-induced muscle atrophy, evidenced in the grip strength and running tests. The GW group showed increased lean body mass, skeletal muscle mass, size, and myosin heavy chain isoform expression, along with reduced skeletal muscle atrophy markers in Dexa-injected mice. Supplementation with GW increased protein synthesis and decreased protein degradation through the Akt/mammalian target of rapamycin and glucocorticoid receptor/forkhead box O3 signaling pathways, respectively. We identified LA as a potential bioactive component of the GW. LA treatment increased myotube diameter and decreased the expression of muscle atrophy markers in Dexa-induced C2C12 cells.

CONCLUSIONS

These findings underscore the potential of the GW in preventing Dexa-induced skeletal muscle atrophy and highlight the contribution of LA to its effects.

Effects of Dietary Lycopene on the Growth Performance, Antioxidant Capacity, Meat Quality, Intestine Histomorphology, and Cecal Microbiota in Broiler Chickens

The experiment aimed to investigate the effects of dietary lycopene on the growth performance, antioxidant capacity, meat quality, intestine histomorphology, and cecal microbiota in broiler chickens. We randomly divided five hundred and seventy-six one-day-old male broilers into four groups each with six replicates and 24 chickens in each replicate. The control group (CG) was fed the basal diet, and the other groups were given powder lycopene of 10, 20, and 30 mg/kg lycopene (LP10, LP20, and LP30, respectively). Compared with the control group, (1) the dietary lycopene increased (p = 0.001) the average daily gain and decreased (p = 0.033) the feed conversion ratio in the experimental groups; (2) the glutathione peroxidase enzyme contents in LP20 were higher (p =< 0.001) in myocardium; (3) the crude protein contents were higher (p = 0.007) in the group treated with 30 mg/kg dietary lycopene; (4) the jejunum villous height was higher (p = 0.040) in LP20; (5) the Unclassified-f-Ruminococcaceae relative abundance was significantly higher (p = 0.043) in LP20. In this study, adding 20 mg/kg dietary lycopene to the broiler chickens' diets improved the growth performance, antioxidant capacity, meat quality, intestine histomorphology, and cecal microbiota in broiler chickens.

The sources, properties, extraction, biosynthesis, pharmacology, and application of lycopene

Lycopene is an important pigment with an alkene skeleton from Lycopersicon esculentum, which is also obtained from some red fruits and vegetables. Lycopene is used in the food field with rich functions and serves in the medical field with multiple clinical values because it has dual functions of both medicine and food. It was found that lycopene was mainly isolated by solvent extraction, ultrasonic-assisted extraction, supercritical fluid extraction, high-intensity pulsed electric field-assisted extraction, enzymatic-assisted extraction, and microwave-assisted extraction. Meanwhile, it was also obtained via 2 synthetic pathways: chemical synthesis and biosynthesis. Pharmacological studies revealed that lycopene has anti-oxidant, hypolipidemic, anti-cancer, immunity-enhancing, hepatoprotective, hypoglycemic, cardiovascular-protective, anti-inflammatory, neuroprotective, and osteoporosis-inhibiting effects. The application of lycopene mainly includes food processing, animal breeding, and medical cosmetology fields. It is hoped that this review will provide some useful information and guidance for future study and exploitation of lycopene.

BATF relieves hepatic steatosis by inhibiting PD1 and promoting energy metabolism

The rising prevalence of nonalcoholic fatty liver disease (NAFLD) has become a global health threat that needs to be addressed urgently. Basic leucine zipper ATF-like transcription factor (BATF) is commonly thought to be involved in immunity, but its effect on lipid metabolism is not clear. Here, we investigated the function of BATF in hepatic lipid metabolism. BATF alleviated high-fat diet (HFD)-induced hepatic steatosis and inhibited elevated programmed cell death protein (PD)1 expression induced by HFD. A mechanistic study confirmed that BATF regulated fat accumulation by inhibiting PD1 expression and promoting energy metabolism. PD1 antibodies alleviated hepatic lipid deposition. In conclusion, we identified the regulatory role of BATF in hepatic lipid metabolism and that PD1 is a target for alleviation of NAFLD. This study provides new insights into the relationship between BATF, PD1, and NAFLD.

A New lncRNA, lnc-LLMA, Regulates Lipid Metabolism in Pig Hepatocytes

A large variety of long noncoding RNAs (lncRNAs) have been discovered through high-throughput sequencing technology and some have been demonstrated to play important roles in lipid metabolism regulation. In our study, we found a highly expressed lncRNA (lnc-LLMA, liver lipid metabolism-associated lncRNA) in the liver of Duroc pigs, which was enriched in the nucleus. It displays potent tissue specificity among different pig breeds. Overexpression of lnc-LLMA can cause a decline in intracellular triglyceride (TG) levels and increases in ATP and mitochondrial DNA levels in pig primary hepatocytes and HepG2 cells. In addition, the expression levels of MTTP, APOB, CPT1α, and other genes were increased by overexpression of lnc-LLMA. It downregulated expression of G6Pase and SREBP1 genes. Chromatin isolation by RNA purification (ChRIP) experiments demonstrated that microsomal triglyceride transfer protein (MTTP) and glycogen synthase 2 (GYS2) were the potential interacting proteins of lnc-LLMA. The overexpression of the GYS2 gene rescued the decreasing intracellular TG levels caused by the increase of lnc-LLMA. Similarly, overexpression of MTTP was also able to save the lnc-LLMA-induced decrease in intracellular TG. Our study demonstrated that this novel lncRNA was closely related to lipid metabolism and affected lipid transport and mitochondrial function through MTTP and GYS2. Our results provided a new direction for further studying the effect of lncRNA on lipid metabolism regulation.

Carotenoid transporter CD36 expression depends on hypoxia-inducible factor-1α in mouse soleus muscles

Dietary β-carotene induces muscle hypertrophy and prevents muscle atrophy in red slow-twitch soleus muscles, but not in white fast-twitch extensor digitorum longus (EDL) muscles and gastrocnemius muscles. However, it remains unclear why these beneficial effects of β-carotene are elicited in soleus muscles. To address this issue, we focused on carotenoid transporters in skeletal muscles. In mice, Cd36 mRNA levels were higher in red muscle than in white muscle. The siRNA-mediated knockdown of CD36 decreased β-carotene uptake in C2C12 myotubes. In soleus muscles, CD36 knockdown inhibited β-carotene-induced increase in muscle mass. Intravenous injection of the hypoxia marker pimonidazole produced more pimonidazole-bound proteins in soleus muscles than in EDL muscles, and the hypoxia-inducible factor-1 (HIF-1) α protein level was higher in soleus muscles than in EDL muscles. In C2C12 myotubes, hypoxia increased the expression of CD36 and HIF-1α at the protein and mRNA levels, and HIF-1α knockdown reduced hypoxia-induced increase in Cd36 mRNA level. In soleus muscles, HIF-1α knockdown reduced Cd36 mRNA level. These results indicate that CD36 is predominantly involved in β-carotene-induced increase in soleus muscle mass of mice. Furthermore, we demonstrate that CD36 expression depends on HIF-1α in the soleus muscles of mice, even under normal physiological conditions.

Translatomics Probes Into the Role of Lycopene on Improving Hepatic Steatosis Induced by High-Fat Diet

Liver is an important organ for fat metabolism. Excessive intake of a high-fat/energy diet is a major cause of hepatic steatosis and its complications such as non-alcoholic fatty liver disease and non-alcoholic steatohepatitis. Supplementation with lycopene, a natural compound, is effective in lowering triglyceride levels in the liver, although the underlying mechanism at the translational level is unclear. In this study, mice were fed a high-fat diet (HFD) to induce hepatic steatosis and treated with or without lycopene. Translation omics and transcriptome sequencing were performed on the liver to explore the regulatory mechanism of lycopene in liver steatosis induced by HFD, and identify differentially expressed genes (DEGs). We identified 1,358 DEGs at the translational level. Through transcriptomics and translatomics joint analysis, we narrowed the range of functional genes to 112 DEGs and found that lycopene may affect lipid metabolism by regulating the expression of LPIN1 at the transcriptional and translational levels. This study provides a powerful tool for translatome and transcriptome integration and a new strategy for the screening of candidate genes.

Integrated Transcriptomic and Translatomic Inquiry of the Role of Betaine on Lipid Metabolic Dysregulation Induced by a High-Fat Diet

An excessive high-fat/energy diet is a major cause of obesity and linked complications, such as non-alcoholic fatty liver disease (NAFLD). Betaine has been shown to effectively improve hepatic lipid metabolism. However, the mechanistic basis for this improvement is largely unknown. Herein, integration of mRNA sequencing and ribosome footprints profiling (Ribo-seq) was used to investigate the means by which betaine alleviates liver lipid metabolic disorders induced by a high-fat diet. For the transcriptome, gene set enrichment analysis demonstrated betaine to reduce liver steatosis by up-regulation of fatty acid beta oxidation, lipid oxidation, and fatty acid catabolic processes. For the translatome, 574 differentially expressed genes were identified, 17 of which were associated with the NAFLD pathway. By combined analysis of transcriptome and translatome, we found that betaine had the greater effect on NAFLD at the translational level. Further, betaine decreased translational efficiency (TE) for IDI1, CYP51A1, TM7SF2, and APOA4, which are related to lipid biosynthesis. In summary, this study demonstrated betaine alleviating lipid metabolic dysfunction at the translational level. The transcriptome and translatome data integration approach used herein provides for a new understanding of the means by which to treat NAFLD.

Naringin Promotes Skeletal Muscle Fiber Remodeling by the AdipoR1-APPL1-AMPK Signaling Pathway

Naringin, a natural flavonoid mainly found in citrus fruit, has been reported to exert a positive effect on improving skeletal muscle health. However, the effects and potential mechanisms of naringin on skeletal muscle fiber switching is still unclear. Here, we discovered that oral administration of naringin increased the low-speed running time, four-limb hanging time, body oxygen consumption in mice, enhanced aerobic enzyme activity, MyHC I expression, and slow-twitch fiber percentage in mice skeletal muscle. By contrast, naringin decreased α-GPDH enzyme activity, MyHC IIb expression, and fast-twitch fiber percentage. Moreover, naringin increased the concentration of serum adiponectin and activated the expression of AdipoR1, APPL1, AMPK, and PGC-1α. Furthermore, by the in vitro experiment and AdipoR1 knockdown, we found that inhibition of the AdipoR1 signaling pathway significantly reduced the effect of naringin on slow-twitch fiber-/fast-twitch fiber-related gene and protein expression. In conclusion, our results indicated that naringin could induce skeletal muscle fiber transition from fast twitch to slow twitch via the AdipoR1 signaling pathway. This study may provide new strategy for improving exercise endurance and slow muscle fiber deficiency-related diseases.

Carotenoids: Therapeutic Strategy in the Battle against Viral Emerging Diseases, COVID-19: An Overview

Carotenoids, a group of phytochemicals, are naturally found in the Plant kingdom, particularly in fruits, vegetables, and algae. There are more than 600 types of carotenoids, some of which are thought to prevent disease, mainly through their antioxidant properties. Carotenoids exhibit several biological and pharmaceutical benefits, such as anti-inflammatory, anti-cancer, and immunity booster properties, particularly as some carotenoids can be converted into vitamin A in the body. However, humans cannot synthesize carotenoids and need to obtain them from their diets or via supplementation. The emerging zoonotic virus severe acute respiratory syndrome coronavirus 2, which causes coronavirus disease 2019 (COVID-19), originated in bats, and was transmitted to humans. COVID-19 continues to cause devastating international health problems worldwide. Therefore, natural preventive therapeutic strategies from bioactive compounds, such as carotenoids, should be appraised for strengthening physiological functions against emerging viruses. This review summarizes the most important carotenoids for human health and enhancing immunity, and their potential role in COVID-19 and its related symptoms. In conclusion, promising roles of carotenoids as treatments against emerging disease and related symptoms are highlighted, most of which have been heavily premeditated in studies conducted on several viral infections, including COVID-19. Further in vitro and in vivo research is required before carotenoids can be considered as potent drugs against such emerging diseases.

Dietary calcium supplementation promotes the accumulation of intramuscular fat

BACKGROUND

In the livestock industry, intramuscular fat content is a key factor affecting meat quality. Many studies have shown that dietary calcium supplementation is closely related to lipid metabolism. However, few studies have examined the relationship between dietary calcium supplementation and intramuscular fat accumulation.

METHODS

Here, we used C2C12 cells, C57BL/6 mice (n = 8) and three-way cross-breeding pigs (Duroc×Landrace×Large white) (n = 10) to study the effect of calcium addition on intramuscular fat accumulation. In vitro, we used calcium chloride to adjust the calcium levels in the medium (2 mmol/L or 3 mmol/L). Then we measured various indicators. In vivo, calcium carbonate was used to regulate calcium levels in feeds (Mice: 0.5% calcium or 1.2% calcium) (Pigs: 0.9% calcium or 1.5% calcium). Then we tested the mice gastrocnemius muscle triglyceride content, pig longissimus dorsi muscle meat quality and lipidomics.

RESULTS

In vitro, calcium addition (3 mmol/L) had no significant effect on cell proliferation, but promoted the differentiation of C2C12 cells into slow-twitch fibers. Calcium supplementation increased triglyceride accumulation in C2C12 cells. Calcium addition increased the number of mitochondria and also increased the calcium level in the mitochondria and reduced the of key enzymes activity involved in β-oxidation such as acyl-coenzyme A dehydrogenase. Decreasing mitochondrial calcium level can alleviate lipid accumulation induced by calcium addition. In addition, calcium addition also reduced the glycolytic capacity and glycolytic conversion rate of C2C12 cells. In vivo, dietary calcium supplementation (1.2%) promoted the accumulation of triglycerides in the gastrocnemius muscle of mice. Dietary calcium supplementation (1.5%) had no effect on pig weight, but significantly improved the flesh color of the longissimus dorsi muscle, reduced the backfat thickness and increased intramuscular fat content in pigs. Besides, calcium addition had no effect on longissimus dorsi pH, electrical conductivity and shear force.

CONCLUSIONS

These results suggest that calcium addition promotes intramuscular fat accumulation by inhibiting the oxidation of fatty acids. These findings provide a new tool for increasing intramuscular fat content and an economical strategy for improving meat quality.

Moderate calorie restriction ameliorates reproduction via attenuating oxidative stress-induced apoptosis through SIRT1 signaling in obese mice

Background

Obesity is a growing global public health problem. It has been associated with diabetes, cardiovascular disease, cancer, and an increased risk of all-cause mortality, as well as infertility. Calorie restriction (CR) is an effective life intervention to defend against obesity. This study aimed to investigate the effects of long-term moderate CR on the reproductive function and underlying mechanisms in a mouse model of obesity.

Methods

Male C57BL/6 mice were randomized to two groups receiving either a standard diet (STD) or a high-fat diet (HFD) for 8 weeks to induce obesity. The HFD-induced obesity mice were further randomized into two groups: HFD group and CR group (reduced the mean amount of HFD by 25%). After 12 weeks, the body weight, testicular coefficients, fasting blood glucose (FBG), serum triglyceride (TG), and total cholesterol (TC) were detected and measured. The sperm quality was detected by an automatic sperm quality analyzer (SQA-V). The structure of testicular tissues was examined by hematoxylin and eosin (HE) staining. Testicular cell apoptosis was assessed by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. The levels of NAD-dependent deacetylase sirtuin-1 (SIRT1) and antioxidative enzymes were detected in the testes.

Results

CR treatment reduced weight gain and increased testicle coefficients in HFD-induced obese mice. CR reduced the serum level of FBG, TG, and TC, and increased the serum levels of testosterone. Moreover, CR increased sperm count and motility, and sperm normality in obese mice. Furthermore, CR ameliorated the testicular morphological damage and cell apoptosis in obese mice. CR also attenuated the oxidative stress level and increased the protein expressions of SIRT1 in testicular tissues of obese mice.

Conclusions

Long-term moderate CR improves obese male fertility, probably by alleviating oxidative stress via activation of SIRT1 signaling.

Lipidomic and Transcriptomic Analysis of the Longissimus Muscle of Luchuan and Duroc Pigs

Meat is an essential food, and pork is the largest consumer meat product in China and the world. Intramuscular fat has always been the basis for people to select and judge meat products. Therefore, we selected the Duroc, a western lean pig breed, and the Luchuan, a Chinese obese pig breed, as models, and used the longissimus dorsi muscle for lipidomics testing and transcriptomics sequencing. The purpose of the study was to determine the differences in intramuscular fat between the two breeds and identify the reasons for the differences. We found that the intramuscular fat content of Luchuan pigs was significantly higher than that of Duroc pigs. The triglycerides and diglycerides related to flavor were higher in Luchuan pigs compared to Duroc pigs. This phenotype may be caused by the difference in the expression of key genes in the glycerolipid metabolism signaling pathway.

High-Fat Diet-Induced Mitochondrial Dysfunction Promotes Genioglossus Injury - A Potential Mechanism for Obstructive Sleep Apnea with Obesity

PURPOSE

Obesity is a worldwide metabolic disease and a critical risk factor for several chronic conditions. Obstructive sleep apnea (OSA) is an important complication of obesity. With the soaring morbidity of obesity, the prevalence of OSA has markedly increased. However, the underlying mechanism of the high relevance between obesity and OSA has not been elucidated. This study investigated the effects of obesity on the structure and function of the genioglossus to explore the possible mechanisms involved in OSA combined with obesity.

METHODS

Six-week-old male C57BL/6J mice were fed high-fat diet (HFD, 60% energy) or normal diet (Control, 10% energy) for 16 weeks. The muscle fibre structure and electromyography (EMG) activity of genioglossus were measured. The ultrastructure and function of mitochondrial, oxidative damage and apoptosis in genioglossus were detected by transmission electron microscopy (TEM), qPCR, Western blotting, immunohistochemistry and TUNEL staining. We further studied the influence of palmitic acid (PA) on the proliferation and myogenic differentiation of C2C12 myoblasts, as well as mitochondrial function, oxidative stress, and apoptosis in C2C12 myotubes.

RESULTS

Compared with the control, the number of muscle fibres was decreased, the fibre type was remarkably changed, and the EMG activity had declined in genioglossus. In addition, a HFD also reduced mitochondria quantity and function, induced excessive oxidative stress and increased apoptosis in genioglossus. In vitro, PA treatment significantly inhibited the proliferation and myogenic differentiation of C2C12 myoblasts. Moreover, PA decreased the mitochondrial membrane potential, upregulated mitochondrial reactive oxygen species (ROS) levels, and activated the mitochondrial-related apoptotic pathway in myotubes.

CONCLUSION

Our findings suggest that a HFD caused genioglossus injury in obese mice. The mitochondrial dysfunction and the accompanying oxidative stress were involved in the genioglossus injury, which may provide potential therapeutic targets for OSA with obesity.