Protective effects of taurine against muscle damage induced by diquat in 35 days weaned piglets

Background: Oxidative stress is a key factor that influences piglets' health. Taurine plays an imperative role in keeping the biological system from damage. This study was conducted to investigate the protective effect of taurine against muscle injury due to the secondary effect of diquat toxicity.Results: Our study found that taurine effectively and dose-dependently alleviated the diquat toxicity induced rise of feed/gain, with a concurrent improvement of carcass lean percentage. The plasma content of taurine was considerably increased in a dose-dependent manner. Consequently, dietary taurine efficiently improved the activity of plasma antioxidant enzymes. Furthermore, taurine attenuated muscle damage by restoring mitochondrial micromorphology, suppressing protein degradation and reducing the percentage of apoptotic cells in the skeletal muscle. Taurine supplementation also suppressed the genes expression levels of the antioxidant-, mitochondrial biogenesis-, and muscle atrophy-related genes in the skeletal muscle of piglets with oxidative stress.Conclusions: These results showed that the dose of 0.60% taurine supplementation in the diet could attenuate skeletal muscle injury induced by diquat toxicity. It is suggested that taurine could be a potential nutritional intervention strategy to improve growth performance.

Effects of dietary protein restriction on muscle fiber characteristics and m TORC1 pathway in the skeletal muscle of growing-finishing pigs

Background： To investigate the effects of dietary crude protein（CP） restriction on muscle fiber characteristics and key regulators related to protein deposition in skeletal muscle, a total of 18 growing-finishing pigs（62.30 ± 0.88 kg）were allotted to 3 groups and fed with the recommended adequate protein（AP, 16 % CP） diet, moderately restricted protein（MP, 13 % CP） diet and low protein（LP, 10 % CP） diet, respectively. The skeletal muscle of different locations in pigs, including longissimus dorsi muscle（LDM）, psoas major muscle（PMM） and biceps femoris muscle（BFM） were collected and analyzed.Results： Results showed that growing-finishing pigs fed the MP or AP diet improved（P 〈 0.01） the average daily gain and feed： gain ratio compared with those fed the LP diet, and the MP diet tended to increase（P = 0.09） the weight of LDM. Moreover, the ATP content and energy charge value were varied among muscle samples from different locations of pigs fed the reduced protein diets. We also observed that pigs fed the MP diet up-regulated（P 〈 0.05） muscular m RNA expression of all the selected key genes, except that myosin heavy chain（My HC） IIb,My HC IIx, while m RNA expression of ubiquitin ligases genes was not affected by dietary CP level. Additionally, the activation of mammalian target of rapamycin complex 1（m TORC1） pathway was stimulated（P 〈 0.05） in skeletal muscle of the pigs fed the MP or AP diet compared with those fed the LP diet.Conclusion： The results suggest that the pigs fed the MP diet could catch up to the growth performance and the LDM weight of the pigs fed the AP diet, and the underlying mechanism may be partly due to the alteration in energy status, modulation of muscle fiber characteristics and m TORC1 activation as well as its downstream effectors in skeletal muscle of different locations in growing-finishing pigs.

Leucine regulates lipid metabolism in adipose tissue through adipokine-mTOR-SIRT1 signaling pathway and bile acid—microbe axis in a finishing pig model

This study was conducted to explore the regulatory mechanism of leucine(Leu)on lipid metabolism of finishing pigs.Twenty-four Duroc×Landrace×Large cross pigs with an average body weight of68.33±0.97 kg were randomly allocated into 3 treatment groups with 8 replicates per group(1 pig per replicate).The dietary treatments were as follows:control group(CON),0.25%Leu group and 0.50%Leu group.The experimental period was 42 d.The results showed as follows.(1)Compared with the CON,0.25%and 0.50%Leu increased(P<0.01)the average daily gain(ADG),while the average backfat thickness(ABT)and the ratio of feed intake to body weight gain(F:G ratio)were decreased(P<0.05).(2)In the 0.25%Leu group,the relative mRNA expression levels of sterol regulatory element binding protein-1c(SREBP1c),recombinant fatty acid transport protein 1(FATP1),chemerin and peroxisome proliferatoractivated receptorγ(PPARγ)were decreased but the level of fatty acid binding protein 4(FABP4)and fatty acid translocase(FAT/CD36)were increased in backfat tissue.In the 0.25%Leu group,the protein levels of p-Rictor,p-Raptor,p-eIF4E-binding protein 1(p-4EBP1),p-silent mating type information regulator 2homolog 1(p-SIRT1)and acetylation ribosome s6 protein kinase 1(Ac—S6K1)were increased(P<0.05).(3)Compared to the CON,the diversity of gut microbiota in the 0.25%Leu group was increased.Principal component analysis showed that the relative abundance of Bacteroidetes,Lactobacillus and Desulfovibrio was higher in the 0.25%Leu group than the CON,but the relative abundance of Firmicutes,Treponema and Shigella was lower than in the CON(P<0.05).(4)Four different metabolites were screened out from the serum of finishing pigs including allolithocholic acid(alloLCA),isolithocholic acid(isoLCA),ursodeoxycholic acid(UDCA)and hyodeoxycholic acid(HDCA),which correlate to various degrees with the above microorganisms.In conclusion,Leu could promote adipose tissue lipolysis of finishing pigs through the mTOR-SIRT1 signaling pathway,and S6K1 is acetylated at the same time,and the interaction between gut microbiota and bile acid metabolism is also involved.

LPS-related muscle loss is associated with the alteration of Bacteroidetes abundance,systemic inflammation,and mitochondrial morphology in a weaned piglet model

We previously demonstrated that lipopolysaccharide(LPS)injection-induced immune stress could impair muscle growth in weaned piglets,but the precise mechanisms behind this remain elusive.Here,we found that chronic immune stress induced by LPS resulted in a significant reduction of 36.86%in the total muscle mass of piglets at 5 d post-treatment compared with the control group.At 1 d,prior to muscle mass loss,multiple alterations were noted in response to LPS treatment.These included a reduction in the abundance of Bacteroidetes,an increase in serum concentrations of pro-inflammatory cytokines,compromised mitochondrial morphology,and an upregulation in the expression of dynamin-related protein 1(Drp1),a critical protein involved in mitochondrial fission.We highlight a strong negative correlation between Bacteroidetes abundance and the levels of serum pro-inflammatory cytokines,corroborated by in vivo intervention strategies in the musculature of both pig and mouse models.Mechanistically,the effects of Bacteroidetes on inflammation and muscle mass loss may involve the signaling pathway of the tauro-β-muricholic acid-fibroblast growth factor 15.Furthermore,the induction of overexpression of inflammatory cytokines,achieved without LPS treatment through oral administration of recombinant human IL-6(rh IL-6),led to increased levels of circulating cytokines,subsequently causing a decrease in muscle mass.Notably,pre-treatment with Mdivi-1,an inhibitor of Drp-1,markedly attenuated the LPS-induced elevation in reactive oxygen species levels and rescued the associated decline in muscle mass.Collectively,these data indicate that LPS-induced muscle mass loss was linked to the reduction of Bacteroidetes abundance,increased inflammation,and the disruption of mitochondrial morphology.These insights offer promising avenues for the identification of potential therapeutic targets aimed at mitigating muscle mass loss.

Antioxidant mechanism of tea polyphenols and its impact on health benefits

Tea trees have a long history of cultivation and utilization.People in many countries have the habit of drinking tea and choosing green tea,oolong tea,or black tea according to different regions and personal tastes.Tea polyphe nols are a general term for polyphenol co mpounds in tea,and has been shown to have good effects on antioxidant,anti-inflammatory,cancer prevention and regulation of lipid metabolism.Tea polyphenols have been widely used as antioxidants in disease treatment and animal husbandry,but their specific mechanism of action needs to be further clarified and revealed.This review focuses on the definition,classification,antioxidant activity and the regulation of signaling pathways of tea polyphenols.This paper also aims to examine the application of tea polyphenols in human and animal health,providing a scientific basis for this application in addition to proposing future directions for the development of this resource.

Oxidative stress, nutritional antioxidants and beyond

Free radical-induced oxidative stress contributes to the development of metabolic syndromes(Mets), including overweight,hyperglycemia, insulin resistance and pro-inflammatory state. Most free radicals are generated from the mitochondrial electron transport chain;under physiological conditions, their levels are maintained by efficient antioxidant systems. A variety of transcription factors have been identified and characterized that control gene expression in response to oxidative stress status.Natural antioxidant compounds have been largely studied for their strong antioxidant capacities. This review discusses the recent progress in oxidative stress and mitochondrial dysfunction in Mets and highlights the anti-Mets, anti-oxidative, and antiinflammatory effect of polyphenols as potential nutritional therapy.

Gut microbial profiles and the role in lipid metabolism in Shaziling pigs

Shaziling pig,a Chinese indigenous breed,has been classified as a fatty pig model.However,the gut microbial development and role in lipid metabolism in Shaziling pigs has been rarely reported.Here,we compared the lipid metabolic and microbial profiles at 30,60,90,150,210,and 300 d of age between Shaziling and Yorkshire pigs.Predictably,there were marked differences in the liver lipids(i.e.,cholesterol,glucose,and low-density lipoprotein)and the lipid related expressions(i.e.,SREBP1/2,LXRa/b,DGAT1/2,and FABP1-3)between Shaziling and Yorkshire pigs.Bacteria sequencing in the ileal digesta and mucosa showed that Shaziling pigs had a higher a-diversity and higher abundances of probiotics,such as Lactobacillus johnsonii,Lactobacillus amylovorus,and Clostridium butyricum.Thirty-five differentiated metabolites were further identified in the mucosa between Shaziling and Yorkshire pigs,which were enriched in the carbohydrate,protein,glucose and amino acid metabolism and bile acid biosynthesis.Furthermore,7 differentiated microbial species were markedly correlated with metabolites,indicating the role of gut microbiota in the host metabolism.Next,the role of differentiated L.johnsonii in lipid metabolism was validated in Duroc×Landrace×Yorkshire(DLY)pigs and the results showed that L.johnsonii mono-colonization promoted lipid deposition and metabolism by altering gut microbiota(i.e.,Megasphaera elsdenii and L.johnsonii)and DGAT1/DGAT2/CD36-PPARg gene expressions.In conclusion,Shaziling pigs exhibited different metabolic and microbial profiles compared with Yorkshire pigs,which might have contributed to the diverse metabolic phenotypes,and the significant enrichment of L.johnsonii in Shaziling pigs promoted lipid metabolism and obesity of DLY pigs,which provided a novel idea to improve the fat content of lean pigs.

Profiles of muscular amino acids,fatty acids,and metabolites in Shaziling pigs of different ages and relation to meat quality

Pork meat is closely related to physicochemical alterations during growth and development,resulting in differences in nutritional value and meat flavor.This study aimed to evaluate the composition of amino acids,fatty acids,and metabolic profiles in the longissimus thoracis muscle(LM)of Shaziling pigs aged 30,90,150,210,and 300 days.The results showed that the predominant fatty acids identified in the LM of Shaziling pigs were C16:0,C16:1,C18:0,C18:1n9c,and C18:2n6c.An opposite correlation was observed for C18:2n6c and n6/n3 polyunsaturated fatty acids(P<0.05).Alanine,aspartate,glutamate,Dglutamine,and D-glutamate metabolism were the main metabolic pathways for the Shaziling pig meat flavor(P<0.05).Moreover,the correlation coefficients revealed that the contents of anserine,C16:0,C16:1,and C18:1n9c were positively correlated with intramuscular fat and/or p H24hand were negatively correlated with the values of L^(*)(lightness)and b^(*)(yellowness)(P<0.05).In conclusion,age greatly affected the meat quality of Shaziling pigs,and the contents of muscular anserine,C16:0,C16:1,and C18:1n9c might be promising indicators for better meat quality.

Dietary supplementation with betaine or glycine improves the carcass trait,meat quality and lipid metabolism of finishing mini-pigs

The objective of the study is to evaluate and compare the effects of betaine or glycine on carcass trait,meat quality and lipid metabolism of finishing Huan Jiang mini-pigs.Betaine called trimethylglycine is a methyl derivative of glycine,but few researches were conducted to compare the impact of dietary betaine and glycine on pigs.One hundred and forty-four Huan Jiang mini-pigs(body weight=10.55±0.15 kg;70 d)were randomly divided to 3 treatment groups(basal diet,glycine or betaine).Results indicated that dietary betaine increased the average daily gain(ADG)and final weight(P<0.05).Dietary glycine or betaine markedly reduced average backfat thickness(P<0.05)and heightened lean percentage(P<0.01)compared to the control group.Moreover,in comparison with the control group,betaine significantly improved the redness(a*)and tenderness(shear force)of the longissimus dorsi(LD)muscle(P<0.05),whereas glycine only raised the value of a*of the LD muscle(P<0.05).These results showed that diet supplemented with 0.25%betaine and equimolar amounts of glycine could regulate cascass trait and meat quality of finishing Huan Jiang mini-pigs,and the effect of betaine was superior to that of glycine.

Supplementation of branched-chain amino acids in protein-restricted diets modulates the expression levels of amino acid transporters and energy metabolism associated regulators in the adipose tissue of growing pigs

This experiment was conducted to investigate the effects of branched-chain amino acids(BCAA)supplemented in protein-restricted diets on the growth performance and the expression profile of amino acid transporters and energy metabolism related regulators in the white adipose tissue(WAT)of different regional depots including dorsal subcutaneous adipose(DSA) and abdominal subcutaneous adipose(ASA), A total of 24 crossbred barrows(7.40 ± 0.70 kg) were randomly divided into 4 groups and were fed the following isocaloric diets for 33 days: 1) a recommended adequate protein diet(AP, 20% CP, as a positive control); 2) a low protein diet(LP, 17% CP); 3) the LP diet supplemented with BCAA(LP + B, 17% CP) to reach the same level of the AP diet group; 4) the LP diet supplemented with 2 times the amount of BCAA(LP + 2B, 17% CP). The daily gain and daily feed intake of the LP diet group were the lowest among all the treatments(P < 0.01). The feed conversion was improved markedly in the group of LP + B compared with the LP diet group(P < 0.05). No significant difference was noted for the serum biochemical parameter concentrations of glucose, triglyceride, nonesterified fatty acid and insulin among the groups(P > 0.05). Moreover, BCAA supplementation down-regulated the expression levels of amino acid transporters including L-type amino acid transporter 1 and sodium-coupled neutral amino acid transporter 2 in DSA, but up-regulated the expression level of Ltype amino acid transporter 4 in ASA(P < 0.05), Meanwhile, the energy sensor AMP-activated protein kinase α was activated in the DSA of pigs fed LP diet and in the ASA of the pigs fed AP or LP + 2B diets(P < 0.05). The mRNA expression profile of the selected mitochondrial component and mitochondrial biogenesis associated regulators in DSA and ASA also responded differently to dietary BCAA supplementation. These results suggested that the growth performance of growing pigs fed protein restricted diets supplemented with BCAA could catch up to that of the pigs fed AP diets. The results also partly demonstrated that the regulation mechanisms of BCAA are different in the adipose tissues of different depots.

Comparisons of carcass traits,meat quality,and serum metabolome between Shaziling and Yorkshire pigs

This study aims to compare the meat quality of Shaziling and Yorkshire pigs and to find the potential indicator in serum for superior meat quality.Six Shaziling and Yorkshire pigs at 30,60,90,150,210,and 300 d of age were selected to examine carcass traits,meat quality,and serum metabolome.The results showed that the body weight,carcass length,and loin eye area of Shaziling pigs at 150,210,and 300 d of age were significantly lower than those of Yorkshire pigs(P<0.05).Shaziling pigs at 150 and 300 d of age had significantly lower backfat thickness than Yorkshire pigs(P<0.05).Compared with Yorkshire pigs,Shaziling pigs at all 6 ages had a lower lean percentage and a higher fat percentage(P<0.05).At 60,90,and 150 d of age,the post-mortem pH-decline,b*value(yellowness),and drip loss of Shaziling pigs were significantly lower than those of Yorkshire pigs(P<0.05).Moreover,at 150 d of age,Shaziling pigs had significantly higher a^(*)value(redness)and intramuscular fat(IMF)content than Yorkshire pigs(P<0.05).Correlation analysis between the top 40 metabolites and phenotypes indicated that L-carnitine had positive correlations with fat percentage,pH24h,and IMF content,but had negative correlations with lean percentage,L^(*)value(lightness),and b^(*)value(P<0.05).Serum L-carnitine content,fat percentage,pH24h,and IMF content all decreased first and then increased as the pigs grew,which verified the positive correlations between L-carnitine and these phenotypes.In conclusion,Shaziling pigs have a slower growth rate but a better meat quality than Yorkshire pigs.The meat quality of Shaziling pigs is the best from 150 to 210 d of age.This study suggests that a higher serum L-carnitine content is a promising indicator for better meat quality.

Engineered Bacillus subtilis alleviates intestinal oxidative injury through Nrf2-Keap1 pathway in enterotoxigenic Escherichia coli(ETEC) K88-infected piglet

Engineered probiotics can serve as therapeutics based on their ability of produce recombinant immune-stimulating properties.In this study,we built the recombinant Bacillus subtilis WB800 expressing antimicrobial peptide KR32(WB800-KR32)using genetic engineering methods and investigated its protective effects of nuclear factor-E2-related factor 2(Nrf2)-Kelch-like ECH-associated protein 1(Keap1)pathway activation in intestinal oxidative disturbance induced by enterotoxigenic Escherichia coli(ETEC)K88 in weaned piglets.Twenty-eight weaned piglets were randomly distributed into four treatment groups with seven replicates fed with a basal diet.The feed of the control group(CON)was infused with normal sterilized saline;meanwhile,the ETEC,ETEC+WB800,and ETEC+WB800-KR32 groups were orally administered normal sterilized saline,5×10^(10)CFU(CFU:colony forming units)WB800,and 5×10^(10)CFU WB800-KR32,respectively,on Days 1-14 and all infused with ETEC K881×10^(10)CFU on Days 15-17.The results showed that pretreatment with WB800-KR32 attenuated ETEC-induced intestinal disturbance,improved the mucosal activity of antioxidant enzyme(catalase(CAT),superoxide dismutase(SOD),and glutathione peroxidase(GPx))and decreased the content of malondialdehyde(MDA).More importantly,WB800-KR32 downregulated genes involved in antioxidant defense(GPx and SOD1).Interestingly,WB800-KR32 upregulated the protein expression of Nrf2 and downregulated the protein expression of Keap1 in the ileum.WB800-KR32 markedly changed the richness estimators(Ace and Chao)of gut microbiota and increased the abundance of Eubacterium_rectale_ATCC_33656 in the feces.The results suggested that WB800-KR32 may alleviate ETEC-induced intestinal oxidative injury through the Nrf2-Keap1 pathway,providing a new perspective for WB800-KR32 as potential therapeutics to regulate intestinal oxidative disturbance in ETEC K88 infection.

Effectiveness and safety evaluation of graded levels of N-carbamylglutamate in growing-finishing pigs

The aim of this study was as follows:1)to investigate the effects of graded levels of N-carbamylglutamate(NCG)on performance,blood biochemical indexes,carcass traits and related indicators in growingfinishing pigs,and 2)to determine the optimal supplemental level.The toxicity of high-dose(much higher than recommended levels)NCG was assessed by routine blood tests and blood biochemical and histopathologic examinations of the heart,liver,spleen,lung,kidney and stomach.One hundred and forty-four growing-finishing pigs(DurocLarge WhiteLandrace,32.24±1.03 kg)were used in a 74-d experiment and each treatment was replicated 6 times with 4 pigs(2 barrows and 2 gilts)per replicate.The dietary treatments were a corn-soybean meal basal diet supplemented with 0%(control),0.05%,0.1%,0.15%,0.2%or 1%NCG.The first 5 groups were used to explore the optimal supplemental level of NCG,while the control,0.1%and 1%NCG groups were used to explore the safety of high-dose NCG.Compared with the normal control group,the final body weight and average daily gain tended to be higher in the 0.1%group(P=0.08),the lean percentage tended to be higher in the 0.05%group(P=0.07),the levels of free amino acids in the blood significantly increased in the 0.1%group(P<0.05),both 0.1%and 0.15%NCG supplementation increased the levels of nitric oxide(NO)in serum(P=0.07)and muscle growth-and lipid metabolism-related gene expression(P<0.05)and NCG supplementation improved C18:1N9C monounsaturated fatty acids(MUFA)in a dose-dependent manner(P=0.08).In addition,routine blood tests,blood biochemical indexes and histopathological examination revealed no abnormalities.Overall,increasing the levels of NCG did not linearly improve the above indicators;the 0.1%dose showed the best effect,and a high dose(1%)did not pose a toxicity risk.

Myokine interleukin-15 expression profile is different in suckling and weaning piglets

Interleukin-15(IL-15) is a cytokine highly expressed in skeletal muscle. The objective of the present study was to investigate the development of muscle IL-15 expression in suckling piglets and in early weaning piglets(day 14) at each level, that is, mRNA, protein, and secretion. Eight litters(eight piglets per litter) of newborn healthy piglets(Large × White × Landrace) with a similar initial weight(1618.0 ± 140.1 g) were chosen and divided into two groups, Group one used suckling piglets that were killed, respectively, at days 1,7,14,21, and group two used early(day 14) weaning piglets that were killed respectively, at days 15, 17, 19, 21. In group one, IL-15 gene expression levels increased significantly(P < 0.05) along with increased body weight over time. IL-15 protein expression levels in piglets at day 21 of age were higher(P < 0.05) than those in piglets at other ages, and there was no difference(P > 0.05)among piglets at other ages. These findings indicated that increased IL-15 mRNA expression did not result in a corresponding increase of its protein expression. In group two, which used early weaning piglets from days 15-19, IL-15 mRNA and protein expression levels increased constantly(P < 0.05) and were higher(P < 0.05) than those in suckling piglets. Moreover, there was no gain of body weight(P > 0.05) compared with suckling piglets at day 14 of age. However, IL-15 protein expression levels in early weaning piglets at day 21 of age dropped significantly(P < 0.05) to the levels as suckling piglets at day 21 of age, while body weight increased(P < 0.05) markedly to the levels as suckling piglets at day 21 of age. In both groups, the serum IL-15 levels of piglets decreased significantly(P < 0.01) over time. Taken together, our results indicate that IL-15 expression differs in suckling piglets and in weaning piglets. It is speculated that IL-15 may play an important role in counteracting the effects of early weaning stress.

A selectively suppressing amino acid transporter: Sodium-coupled neutral amino acid transporter 2 inhibits cell growth and mammalian target of rapamycin complex 1 pathway in skeletal muscle cells

Sodium-coupled neutral amino acid transporter 2(SNAT2),also known as solute carrier family 38 member 2(SLC38 A2),is expressed in the skeletal muscle.Our research previously indicated that SNAT2 m RNA expression level in the skeletal muscle was modulated by genotype and dietary protein.The aim of this study was to investigate the key role of the amino acid transporter SNAT2 in muscle cell growth,differentiation,and related signaling pathways via SNAT2 suppression using the inhibitor a-methylaminoisobutyric acid(Me AIB).The results showed that SNAT2 suppression down-regulated both the m RNA and protein expression levels of SNAT2 in C2 C12 cells,inhibited cell viability and differentiation of the cell,and regulated the cell distribution in G0/G1 and S phases(P<0.05).Meanwhile,most of the intercellular amino acid content of the cells after Me AIB co-culturing was significantly lower(P<0.05).Furthermore,the m RNA expression levels of system L amino acid transporter 1(LAT1),silent information regulator 1,and peroxisome proliferator-activated receptor-gamma co-activator 1 alpha,as well as the protein expression levels of amino acid transporters LAT1 and vacuolar protein sorting 34,were all down-regulated.The phosphorylated protein expression levels of mammalian target of rapamycin(m TOR),regulatory-associated protein of m TOR,4 E binding protein 1,and ribosomal protein S6 kinase 1 after Me AIB treatment were also significantly down-regulated(P<0.05),which could contribute to the importance of SNAT2 in amino acid transportation and skeletal muscle cell sensing.In conclusion,SNAT2 suppression inhibited C2 C12 cell growth and differentiation,as well as the availability of free amino acids.Although the m TOR complex 1 signaling pathway was found to be involved,its response to different nutrients requires further study.