Background Cold stress has negative effects on the growth and health of mammals, and has become a factor restricting livestock development at high latitudes and on plateaus. The gut-liver axis is central to energy met...Background Cold stress has negative effects on the growth and health of mammals, and has become a factor restricting livestock development at high latitudes and on plateaus. The gut-liver axis is central to energy metabolism, and the mechanisms by which it regulates host energy metabolism at cold temperatures have rarely been illustrated. In this study, we evaluated the status of glycolipid metabolism and oxidative stress in pigs based on the gut-liver axis and propose that AMP-activated protein kinase(AMPK) is a key target for alleviating energy stress at cold temperatures by dietary fat supplementation.Results Dietary fat supplementation alleviated the negative effects of cold temperatures on growth performance and digestive enzymes, while hormonal homeostasis was also restored. Moreover, cold temperature exposure increased glucose transport in the jejunum. In contrast, we observed abnormalities in lipid metabolism, which was characterized by the accumulation of bile acids in the ileum and plasma. In addition, the results of the ileal metabolomic analysis were consistent with the energy metabolism measurements in the jejunum, and dietary fat supplementation increased the activity of the mitochondrial respiratory chain and lipid metabolism. As the central nexus of energy metabolism, the state of glycolipid metabolism and oxidative stress in the liver are inconsistent with that in the small intestine. Specifically, we found that cold temperature exposure increased glucose transport in the liver, which fully validates the idea that hormones can act on the liver to regulate glucose output. Additionally, dietary fat supplementation inhibited glucose transport and glycolysis, but increased gluconeogenesis, bile acid cycling, and lipid metabolism. Sustained activation of AMPK, which an energy receptor and regulator, leads to oxidative stress and apoptosis in the liver;dietary fat supplementation alleviates energy stress by reducing AMPK phosphorylation.Conclusions Cold stress reduced the growth performance and aggravated glycolipid metabolism disorders and oxidative stress damage in pigs. Dietary fat supplementation improved growth performance and alleviated cold temperature-induced energy stress through AMPK-mediated mitochondrial homeostasis. In this study, we high-light the importance of AMPK in dietary fat supplementation-mediated alleviation of host energy stress in response to environmental changes.展开更多
Background Oxidized soybean oil(OSO)has been shown to impair growth and exacerbate inflammation,leading to intestinal barrier injury in animals.Recent evidence suggests important roles for resveratrol(RES)in the promo...Background Oxidized soybean oil(OSO)has been shown to impair growth and exacerbate inflammation,leading to intestinal barrier injury in animals.Recent evidence suggests important roles for resveratrol(RES)in the promoting growth performance,antioxidant capacity,anti-inflammatory,and regulate intestinal barriers in animals.Therefore,The objectives of this study are to investigate the effects of dietary RES(purity 98%)supplementation on the growth performance,antioxidant capacity,inflammatory state,and intestinal function of weaned piglets challenged with OSO.Methods A total of 28 castrated weaned male piglets with a similar body weight of 10.197 replications per treatment and±0.10 kg were randomly assigned to 4 dietary treatments for 28-d feeding trial with 1 piglet per replicate.Treatments were arranged as a 2×2 factorial with oil type[3%fresh soybean oil(FSO)vs.3%OSO]and dietary RES(0vs.300 mg/kg).Results The results showed that relative to the FSO group,OSO stress tended to decrease the average daily feed intake(ADFI),and decreased the activity levels of lipase,villus/crypt ratio(VCR),the mRNA expression of FABP1,SOD2,IL-10 and ZO-1 in the jejunum,and SOD2,GPX1,occludin and ZO-1 in the colon,the levels of acetic acid in the colonic digesta,whereas up-regulated the mRNA expression of IL-1βand TNF-αin the jejunum(P<0.05).Moreover,dietary supplementation with RES increased ether extract(EE),the activity levels of sucrase,lipase,α-amylase,villus height(VH)and VCR,the mRNA expression of FABP1,SOD2,IL-10 and occludin in the jejunum,and FABP1,PPAR-γ,GPX1,occludin and ZO-1 in the colon,and the abundance of Firmicutes,acetic and propionic acid,but decreased the levels of D-lactic acid in the plasma,the abundance of Bacteroidetes in the colonic digesta of weaned piglets compared to the non-RES group(P<0.05).Meanwhile,in the interaction effect analysis,relative to the OSO group,dietary RES supplementation in the diets supplemented with OSO increased the activity levels of trypsin,VH in the jejunum,the abundance of Actinobacteria,the levels of butyric acid of weaned piglets,but failed to influence the activity levels of trypsin and VH,Actinobacteria abundance,the levels of butyric acid when diets were supplemented with FSO(interaction,P<0.05).Relative to the OSO group,dietary RES supplementation in the diets supplemented with OSO decreased the activity levels of DAO in the plasma of weaned piglets but failed to influence the activity levels of DAO when diets were supplemented with FSO(interaction,P<0.05).Relative to the FSO group,dietary RES supplementation in the diets supplemented with FSO decreased the level of propionic acid,whereas RES supplementation failed to influence the level of propionic acid when the diet was supplemented with OSO(interaction,P<0.01).Conclusions Inclusion of OSO intensified inflammatory states and impaired the intestinal health characteristics of weaned piglets.Dietary RES supplementation improved the antioxidant capacity,anti-inflammatory activity,and intestinal morphology.Further studies showed that the protective effects of RES on gut health could be linked to the decreased abundance of Prevotella_1,Clostridium_sensu_stricto_6,and Prevotellaceae_UCG003 and increased levels of acetic and propionic acid.展开更多
Background Cold regions have long autumn and winter seasons and low ambient temperatures.When pigs are unable to adjust to the cold,oxidative damage and inflammation may develop.However,the differences between cold an...Background Cold regions have long autumn and winter seasons and low ambient temperatures.When pigs are unable to adjust to the cold,oxidative damage and inflammation may develop.However,the differences between cold and non-cold adaptation regarding glucose and lipid metabolism,gut microbiota and colonic mucosal immunological features in pigs are unknown.This study revealed the glucose and lipid metabolic responses and the dual role of gut microbiota in pigs during cold and non-cold adaptation.Moreover,the regulatory effects of dietary glucose supplements on glucose and lipid metabolism and the colonic mucosal barrier were evaluated in cold-exposed pigs.Results Cold and non-cold-adapted models were established by Min and Yorkshire pigs.Our results exhibited that cold exposure induced glucose overconsumption in non-cold-adapted pig models(Yorkshire pigs),decreasing plasma glucose concentrations.In this case,cold exposure enhanced the ATGL and CPT-1αexpression to promote liver lipolysis and fatty acid oxidation.Meanwhile,the two probiotics(Collinsella and Bifidobacterium)depletion and the enrichment of two pathogens(Sutterella and Escherichia-Shigella)in colonic microbiota are not conducive to colonic mucosal immunity.However,glucagon-mediated hepatic glycogenolysis in cold-adapted pig models(Min pigs)maintained the stability of glucose homeostasis during cold exposure.It contributed to the gut microbiota(including the enrichment of the Rikenellaceae RC9 gut group,[Eubacterium]coprostanoligenes group and WCHB1-41)that favored cold-adapted metabolism.Conclusions The results of both models indicate that the gut microbiota during cold adaptation contributes to the protection of the colonic mucosa.During non-cold adaptation,cold-induced glucose overconsumption promotes thermogenesis through lipolysis,but interferes with the gut microbiome and colonic mucosal immunity.Furthermore,glucagon-mediated hepatic glycogenolysis contributes to glucose homeostasis during cold exposure.展开更多
Background: Resveratrol, a plant phenol, affords protection against inflammation and oxidative stress. The objective of this study was to investigate the effects of dietary resveratrol supplementation during pregnancy...Background: Resveratrol, a plant phenol, affords protection against inflammation and oxidative stress. The objective of this study was to investigate the effects of dietary resveratrol supplementation during pregnancy and lactation on the antioxidant status of sows and piglets and on antioxidant gene expression and pathway in placenta.Methods: Forty sows were allotted to 2 dietary treatments 20 d after breeding. Sows were fed a control diet and a control diet with 300 mg/kg resveratrol. Oxidative stress biomarkers and antioxidant enzymes were measured in the placenta, milk, and plasma of sows and piglets. Antioxidant gene expression and protein expression of Kelch-like ECH-associated protein 1-Nuclear factor E2-related factor 2(Keap1-Nrf2), nuclear factor kappa B-p65(NFκB-p65) and sirtuin1(Sirt1) were quantified in the placenta.Results: Dietary resveratrol increased the litter and piglets weaning weights. Antioxidant status in the milk, placenta and plasma of sows and piglets was partially improved by dietary resveratrol. In placenta, Nrf2 protein expression was increased and Keap1 protein expression was decreased by dietary resveratrol. The m RNA expression of antioxidant genes including catalase(CAT), glutathione peroxidase 1(GPX1), GPX4, superoxide dismutase 1(SOD1)and heme oxygenase 1(HO1), and phase 2 detoxification genes, including glutamate-cysteine ligase modifier(GCLM), microsomal glutathione S-transferase 1(MGST1) and UDP glucuronosyltransferase family 1 member A1(UGT1 A1), was increased by dietary resveratrol. Dietary resveratrol also increased Sirt1 and phosphorylated NFκB-p65 protein expression in the placenta. We failed to observe any influences of dietary resveratrol on pro-inflammatory cytokine levels, including those of interleukin 1β(IL-1β), IL-6, IL-8 and tumor necrosis factor α(TNF-α). However, we observed that the m RNA expression of IL-8 in placenta was reduced by maternal resveratrol. In addition, dietary resveratrol showed interactive effects with day of lactation on activities of SOD and CAT and levels of malonaldehyde(MDA) and hydrogen peroxide(H2 O2) in milk.Conclusions: Dietary resveratrol supplementation during pregnancy and lactation improves the antioxidant status of sows and piglets, which is beneficial to the reproductive performance of sows. Dietary resveratrol regulates placental antioxidant gene expression by the Keap1-Nrf2 pathway and Sirt1 in placenta.展开更多
Background: Pyrroloquinoline quinone(PQQ), which is a water soluble, thermo-stable triglyceride-quinone, is widely distributed in nature and characterized as a mammalian vitamin-like redox cofactor. The objective of t...Background: Pyrroloquinoline quinone(PQQ), which is a water soluble, thermo-stable triglyceride-quinone, is widely distributed in nature and characterized as a mammalian vitamin-like redox cofactor. The objective of this study was to investigate the effects of pyrroloquinoline quinone disodium(PQQ·Na2) on reproductive performance in sows.Results: Dietary supplementation with PQQ·Na2 significantly increased the total number of piglets born, the number of piglets born alive and the born alive litter weight. It also increased the antioxidant status in the placenta, plasma and milk. The concentration of NO was significantly increased in the plasma and placenta. RNA-seq analysis showed that462 unigenes were differentially expressed between the control(Con) treatment and PQQ treatment groups.Among these unigenes, 199 were upregulated, while 263 unigenes were downregulated. The assigned functions of the unigenes covered a broad range of GO categories. Reproduction(27, 7.03%) and the reproduction process(27, 7.03%) were assigned to the biological process category. By matching DEGs to the KEGG database, we identified 29 pathways.Conclusions: In conclusion, dietary supplementation with PQQ·Na2 in gestating and lactating sows had positive effects on their reproductive performance.展开更多
Mammals in northern regions chronically suffer from low temperatures during autumn-winter seasons.The aim of this study was to investigate the response of intestinal amino acid transport and the amino acid pool in mus...Mammals in northern regions chronically suffer from low temperatures during autumn-winter seasons.The aim of this study was to investigate the response of intestinal amino acid transport and the amino acid pool in muscle to chronic cold exposure via Min pig models(cold adaptation)and Yorkshire pig models(non-cold adaptation).Furthermore,this study explored the beneficial effects of glucose supplementation on small intestinal amino acid transport and amino acid pool in muscle of cold-exposed Yorkshire pigs.Min pigs(Exp.1)and Yorkshire pigs(Exp.2)were divided into a control group(17℃,n=6)and chronic cold exposure group(7℃,n=6),respectively.Twelve Yorkshire pigs(Exp.3)were divided into a cold control group and cold glucose supplementation group(8℃).The results showed that chronic cold exposure inhibited peptide transporter protein 1(PepT1)and excitatory amino acid transporter 3(EAAT3)expression in ileal mucosa and cationic amino acid transporter-1(CAT-1)in the jejunal mucosa of Yorkshire pigs(P<0.05).In contrast,CAT-1,PepT1 and EAAT3 expression was enhanced in the duodenal mucosa of Min pigs(P<0.05).Branched amino acids(BCAA)in the muscle of Yorkshire pigs were consumed by chronic cold exposure,accompanied by increased muscle RING-finger protein-1(MuRF1)and muscle atrophy F-box(atrogin-1)expression(P<0.05).More importantly,reduced concentrations of dystrophin were detected in the muscle of Yorkshire pigs(P<0.05).However,glycine concentration in the muscle of Min pigs was raised(P<0.05).In the absence of interaction between chronic cold exposure and glucose supplementation,glucose supplementation improved CAT-1 expression in the jejunal mucosa and PepT1 expression in the ileal mucosa of cold-exposed Yorkshire pigs(P<0.05).It also improved BCAA and inhibited MuRF1 and atrogin-1 expression in muscle(P<0.05).Moreover,dystrophin concentration was improved by glucose supplementation(P<0.05).In summary,chronic cold exposure inhibits amino acid absorption in the small intestine,depletes BCAA and promotes protein degradation in muscle.Glucose supplementation ameliorates the negative effects of chronic cold exposure on amino acid transport and the amino acid pool in muscle.展开更多
基金funded by the National Key Research and Development Program of China (2021YFD1300403)。
文摘Background Cold stress has negative effects on the growth and health of mammals, and has become a factor restricting livestock development at high latitudes and on plateaus. The gut-liver axis is central to energy metabolism, and the mechanisms by which it regulates host energy metabolism at cold temperatures have rarely been illustrated. In this study, we evaluated the status of glycolipid metabolism and oxidative stress in pigs based on the gut-liver axis and propose that AMP-activated protein kinase(AMPK) is a key target for alleviating energy stress at cold temperatures by dietary fat supplementation.Results Dietary fat supplementation alleviated the negative effects of cold temperatures on growth performance and digestive enzymes, while hormonal homeostasis was also restored. Moreover, cold temperature exposure increased glucose transport in the jejunum. In contrast, we observed abnormalities in lipid metabolism, which was characterized by the accumulation of bile acids in the ileum and plasma. In addition, the results of the ileal metabolomic analysis were consistent with the energy metabolism measurements in the jejunum, and dietary fat supplementation increased the activity of the mitochondrial respiratory chain and lipid metabolism. As the central nexus of energy metabolism, the state of glycolipid metabolism and oxidative stress in the liver are inconsistent with that in the small intestine. Specifically, we found that cold temperature exposure increased glucose transport in the liver, which fully validates the idea that hormones can act on the liver to regulate glucose output. Additionally, dietary fat supplementation inhibited glucose transport and glycolysis, but increased gluconeogenesis, bile acid cycling, and lipid metabolism. Sustained activation of AMPK, which an energy receptor and regulator, leads to oxidative stress and apoptosis in the liver;dietary fat supplementation alleviates energy stress by reducing AMPK phosphorylation.Conclusions Cold stress reduced the growth performance and aggravated glycolipid metabolism disorders and oxidative stress damage in pigs. Dietary fat supplementation improved growth performance and alleviated cold temperature-induced energy stress through AMPK-mediated mitochondrial homeostasis. In this study, we high-light the importance of AMPK in dietary fat supplementation-mediated alleviation of host energy stress in response to environmental changes.
基金supported by the National Natural Science Foundation of China(31872986)。
文摘Background Oxidized soybean oil(OSO)has been shown to impair growth and exacerbate inflammation,leading to intestinal barrier injury in animals.Recent evidence suggests important roles for resveratrol(RES)in the promoting growth performance,antioxidant capacity,anti-inflammatory,and regulate intestinal barriers in animals.Therefore,The objectives of this study are to investigate the effects of dietary RES(purity 98%)supplementation on the growth performance,antioxidant capacity,inflammatory state,and intestinal function of weaned piglets challenged with OSO.Methods A total of 28 castrated weaned male piglets with a similar body weight of 10.197 replications per treatment and±0.10 kg were randomly assigned to 4 dietary treatments for 28-d feeding trial with 1 piglet per replicate.Treatments were arranged as a 2×2 factorial with oil type[3%fresh soybean oil(FSO)vs.3%OSO]and dietary RES(0vs.300 mg/kg).Results The results showed that relative to the FSO group,OSO stress tended to decrease the average daily feed intake(ADFI),and decreased the activity levels of lipase,villus/crypt ratio(VCR),the mRNA expression of FABP1,SOD2,IL-10 and ZO-1 in the jejunum,and SOD2,GPX1,occludin and ZO-1 in the colon,the levels of acetic acid in the colonic digesta,whereas up-regulated the mRNA expression of IL-1βand TNF-αin the jejunum(P<0.05).Moreover,dietary supplementation with RES increased ether extract(EE),the activity levels of sucrase,lipase,α-amylase,villus height(VH)and VCR,the mRNA expression of FABP1,SOD2,IL-10 and occludin in the jejunum,and FABP1,PPAR-γ,GPX1,occludin and ZO-1 in the colon,and the abundance of Firmicutes,acetic and propionic acid,but decreased the levels of D-lactic acid in the plasma,the abundance of Bacteroidetes in the colonic digesta of weaned piglets compared to the non-RES group(P<0.05).Meanwhile,in the interaction effect analysis,relative to the OSO group,dietary RES supplementation in the diets supplemented with OSO increased the activity levels of trypsin,VH in the jejunum,the abundance of Actinobacteria,the levels of butyric acid of weaned piglets,but failed to influence the activity levels of trypsin and VH,Actinobacteria abundance,the levels of butyric acid when diets were supplemented with FSO(interaction,P<0.05).Relative to the OSO group,dietary RES supplementation in the diets supplemented with OSO decreased the activity levels of DAO in the plasma of weaned piglets but failed to influence the activity levels of DAO when diets were supplemented with FSO(interaction,P<0.05).Relative to the FSO group,dietary RES supplementation in the diets supplemented with FSO decreased the level of propionic acid,whereas RES supplementation failed to influence the level of propionic acid when the diet was supplemented with OSO(interaction,P<0.01).Conclusions Inclusion of OSO intensified inflammatory states and impaired the intestinal health characteristics of weaned piglets.Dietary RES supplementation improved the antioxidant capacity,anti-inflammatory activity,and intestinal morphology.Further studies showed that the protective effects of RES on gut health could be linked to the decreased abundance of Prevotella_1,Clostridium_sensu_stricto_6,and Prevotellaceae_UCG003 and increased levels of acetic and propionic acid.
基金supported by the National Key R&D Program of China(2021YFD1300403)the Major Program of Heilongjiang Province of China(2021ZX12B08-02).
文摘Background Cold regions have long autumn and winter seasons and low ambient temperatures.When pigs are unable to adjust to the cold,oxidative damage and inflammation may develop.However,the differences between cold and non-cold adaptation regarding glucose and lipid metabolism,gut microbiota and colonic mucosal immunological features in pigs are unknown.This study revealed the glucose and lipid metabolic responses and the dual role of gut microbiota in pigs during cold and non-cold adaptation.Moreover,the regulatory effects of dietary glucose supplements on glucose and lipid metabolism and the colonic mucosal barrier were evaluated in cold-exposed pigs.Results Cold and non-cold-adapted models were established by Min and Yorkshire pigs.Our results exhibited that cold exposure induced glucose overconsumption in non-cold-adapted pig models(Yorkshire pigs),decreasing plasma glucose concentrations.In this case,cold exposure enhanced the ATGL and CPT-1αexpression to promote liver lipolysis and fatty acid oxidation.Meanwhile,the two probiotics(Collinsella and Bifidobacterium)depletion and the enrichment of two pathogens(Sutterella and Escherichia-Shigella)in colonic microbiota are not conducive to colonic mucosal immunity.However,glucagon-mediated hepatic glycogenolysis in cold-adapted pig models(Min pigs)maintained the stability of glucose homeostasis during cold exposure.It contributed to the gut microbiota(including the enrichment of the Rikenellaceae RC9 gut group,[Eubacterium]coprostanoligenes group and WCHB1-41)that favored cold-adapted metabolism.Conclusions The results of both models indicate that the gut microbiota during cold adaptation contributes to the protection of the colonic mucosa.During non-cold adaptation,cold-induced glucose overconsumption promotes thermogenesis through lipolysis,but interferes with the gut microbiome and colonic mucosal immunity.Furthermore,glucagon-mediated hepatic glycogenolysis contributes to glucose homeostasis during cold exposure.
基金supported by the National Key Research and Development Plan of China(2016YFD0501207)the China Agriculture Research System(CARS-36)the National Basic Research Program(2012CB124703)
文摘Background: Resveratrol, a plant phenol, affords protection against inflammation and oxidative stress. The objective of this study was to investigate the effects of dietary resveratrol supplementation during pregnancy and lactation on the antioxidant status of sows and piglets and on antioxidant gene expression and pathway in placenta.Methods: Forty sows were allotted to 2 dietary treatments 20 d after breeding. Sows were fed a control diet and a control diet with 300 mg/kg resveratrol. Oxidative stress biomarkers and antioxidant enzymes were measured in the placenta, milk, and plasma of sows and piglets. Antioxidant gene expression and protein expression of Kelch-like ECH-associated protein 1-Nuclear factor E2-related factor 2(Keap1-Nrf2), nuclear factor kappa B-p65(NFκB-p65) and sirtuin1(Sirt1) were quantified in the placenta.Results: Dietary resveratrol increased the litter and piglets weaning weights. Antioxidant status in the milk, placenta and plasma of sows and piglets was partially improved by dietary resveratrol. In placenta, Nrf2 protein expression was increased and Keap1 protein expression was decreased by dietary resveratrol. The m RNA expression of antioxidant genes including catalase(CAT), glutathione peroxidase 1(GPX1), GPX4, superoxide dismutase 1(SOD1)and heme oxygenase 1(HO1), and phase 2 detoxification genes, including glutamate-cysteine ligase modifier(GCLM), microsomal glutathione S-transferase 1(MGST1) and UDP glucuronosyltransferase family 1 member A1(UGT1 A1), was increased by dietary resveratrol. Dietary resveratrol also increased Sirt1 and phosphorylated NFκB-p65 protein expression in the placenta. We failed to observe any influences of dietary resveratrol on pro-inflammatory cytokine levels, including those of interleukin 1β(IL-1β), IL-6, IL-8 and tumor necrosis factor α(TNF-α). However, we observed that the m RNA expression of IL-8 in placenta was reduced by maternal resveratrol. In addition, dietary resveratrol showed interactive effects with day of lactation on activities of SOD and CAT and levels of malonaldehyde(MDA) and hydrogen peroxide(H2 O2) in milk.Conclusions: Dietary resveratrol supplementation during pregnancy and lactation improves the antioxidant status of sows and piglets, which is beneficial to the reproductive performance of sows. Dietary resveratrol regulates placental antioxidant gene expression by the Keap1-Nrf2 pathway and Sirt1 in placenta.
基金supported by the National Key Research and Development Plan of China(2016YFD0501207)the China Agriculture Research System(CARS-36)
文摘Background: Pyrroloquinoline quinone(PQQ), which is a water soluble, thermo-stable triglyceride-quinone, is widely distributed in nature and characterized as a mammalian vitamin-like redox cofactor. The objective of this study was to investigate the effects of pyrroloquinoline quinone disodium(PQQ·Na2) on reproductive performance in sows.Results: Dietary supplementation with PQQ·Na2 significantly increased the total number of piglets born, the number of piglets born alive and the born alive litter weight. It also increased the antioxidant status in the placenta, plasma and milk. The concentration of NO was significantly increased in the plasma and placenta. RNA-seq analysis showed that462 unigenes were differentially expressed between the control(Con) treatment and PQQ treatment groups.Among these unigenes, 199 were upregulated, while 263 unigenes were downregulated. The assigned functions of the unigenes covered a broad range of GO categories. Reproduction(27, 7.03%) and the reproduction process(27, 7.03%) were assigned to the biological process category. By matching DEGs to the KEGG database, we identified 29 pathways.Conclusions: In conclusion, dietary supplementation with PQQ·Na2 in gestating and lactating sows had positive effects on their reproductive performance.
基金This work was supported by the National Key R&D Program of China(2021YFD1300403)the Major Program of Heilongjiang Province of China(2021ZX12B08-02).
文摘Mammals in northern regions chronically suffer from low temperatures during autumn-winter seasons.The aim of this study was to investigate the response of intestinal amino acid transport and the amino acid pool in muscle to chronic cold exposure via Min pig models(cold adaptation)and Yorkshire pig models(non-cold adaptation).Furthermore,this study explored the beneficial effects of glucose supplementation on small intestinal amino acid transport and amino acid pool in muscle of cold-exposed Yorkshire pigs.Min pigs(Exp.1)and Yorkshire pigs(Exp.2)were divided into a control group(17℃,n=6)and chronic cold exposure group(7℃,n=6),respectively.Twelve Yorkshire pigs(Exp.3)were divided into a cold control group and cold glucose supplementation group(8℃).The results showed that chronic cold exposure inhibited peptide transporter protein 1(PepT1)and excitatory amino acid transporter 3(EAAT3)expression in ileal mucosa and cationic amino acid transporter-1(CAT-1)in the jejunal mucosa of Yorkshire pigs(P<0.05).In contrast,CAT-1,PepT1 and EAAT3 expression was enhanced in the duodenal mucosa of Min pigs(P<0.05).Branched amino acids(BCAA)in the muscle of Yorkshire pigs were consumed by chronic cold exposure,accompanied by increased muscle RING-finger protein-1(MuRF1)and muscle atrophy F-box(atrogin-1)expression(P<0.05).More importantly,reduced concentrations of dystrophin were detected in the muscle of Yorkshire pigs(P<0.05).However,glycine concentration in the muscle of Min pigs was raised(P<0.05).In the absence of interaction between chronic cold exposure and glucose supplementation,glucose supplementation improved CAT-1 expression in the jejunal mucosa and PepT1 expression in the ileal mucosa of cold-exposed Yorkshire pigs(P<0.05).It also improved BCAA and inhibited MuRF1 and atrogin-1 expression in muscle(P<0.05).Moreover,dystrophin concentration was improved by glucose supplementation(P<0.05).In summary,chronic cold exposure inhibits amino acid absorption in the small intestine,depletes BCAA and promotes protein degradation in muscle.Glucose supplementation ameliorates the negative effects of chronic cold exposure on amino acid transport and the amino acid pool in muscle.
