Effects of Dietary l-Glutamine Supplementation on the Intestinal Function and Muscle Growth of Piglets.

The aim of this study was to investigate the effects of dietary l-glutamine (Gln) supplementation on the morphology and function of the intestine and the growth of muscle in piglets. In this study, sixteen 21-day-old piglets were randomly divided into two groups: the Control group (fed a basal diet) and the Gln group (fed a basal diet supplemented with 0.81% Gln). Blood, gut, and muscle samples were collected from all piglets on Day 20 of the trial. Compared with the Control group, the supplementation of Gln increased (p < 0.05) the villus height, villus width, villus surface area, and villus height/crypt depth ratio of the small intestine. Furthermore, the supplementation of Gln increased (p < 0.05) total protein, total protein/DNA, and RNA/DNA in both the jejunum and ileum. It also increased (p < 0.05) the concentrations of carnosine and citrulline in the jejunal mucosa, as well as citrulline and cysteine concentrations in the ileum. Conversely, Gln supplementation decreased (p < 0.05) Gln concentrations in both the jejunum and ileum, along with ß-aminoisobutyric acid and 1-Methylhistidine concentrations, specifically in the ileum. Subsequent research revealed that Gln supplementation increased (p < 0.05) the mRNA levels for glutathione-S-transferase omega 2 and interferon-ß in the duodenum. In addition, Gln supplementation led to an increase (p < 0.05) in the number of Lactobacillus genus in the colon, but a decrease (p < 0.05) in the level of HSP70 in the jejunum and the activity of diamine oxidase in plasma. Also, Gln supplementation reduced (p < 0.05) the mRNA levels of glutathione-S-transferase omega 2 and interferon stimulated genes, such as MX1, OAS1, IFIT1, IFIT2, IFIT3, and IFIT5 in both the jejunum and ileum, and the numbers of Clostridium coccoides, Enterococcus genus, and Enterobacterium family in the colon. Moreover, Gln supplementation enhanced (p < 0.05) the concentrations of total protein, RNA/DNA, and total protein/DNA ratio in the longissimus dorsi muscle, the concentrations of citrulline, ornithine, arginine, and hydroxyproline, and the mRNA level of peptide transporter 1, while reducing the contents of hydrogen peroxide and malondialdehyde and the mRNA level of glutathione-S-transferase omega 2 in the longissimus dorsi muscle. In conclusion, dietary Gln supplementation can improve the intestinal function of piglets and promote the growth of the longissimus dorsi muscle.

Effects of a mixture of glycerol monolaurate and cinnamaldehyde supplementation on laying performance, egg quality, and antioxidant status in laying hens.

BACKGROUND: This study aimed to determine the effects of a mixture of glycerol monolaurate and cinnamaldehyde (GCM) supplementation on the laying performance, egg quality, antioxidant capacity, and serum parameters of laying hens. A total of 1120 14-week-old Jingfen-1 strain laying hens with similar performance were randomly allocated to four dietary treatments: control, and GCM groups supplemented with 250, 500, or 1000 mg kg-1 for 12 weeks. RESULTS: Compared with the control group, GCM-supplemented groups significantly reduced (P < 0.05) the rate of unqualified eggs of laying hens aged 17-24 weeks. Supplementation of GCM significantly increased (P < 0.05) yolk color and serum glutathione peroxidase (GSH-Px) activity but decreased (P < 0.05) the hydrogen peroxide (H2 O2 ) content in the serum of laying hens at the age of 20 weeks. Furthermore, groups supplemented with GCM showed a significant increase (P < 0.05) in Haugh unit, yolk color, activities of total superoxide dismutase and GSH-Px, and the glucose content in serum, and a decrease (P < 0.05) in the content of urea nitrogen and H2 O2 and malondialdehyde in serum of laying hens at the age of 24 weeks. 500 mg kg-1 GCM supplementation significantly increased (P < 0.05) the number of large white follicles and 1000 mg kg-1 GCM supplementation decreased the number of large yellow follicles in 28-week-old laying hens. CONCLUSION: These results indicated that GCM supplementation has positive effects on reducing egg loss and improving egg quality in the early laying period of laying hens. © 2023 Society of Chemical Industry.

Effects of Vitamin A on Immune Responses and Vitamin A Metabolism in Broiler Chickens Challenged with Necrotic Enteritis.

Necrotic enteritis (NE) is an important enteric inflammatory disease of poultry, and the effects of vitamin A (VitA) on NE birds are largely unknown. The present study was conducted to investigate the effects of VitA on the immune responses and VitA metabolism of NE broilers as well as the underlying mechanisms. Using a 2 × 2 factorial arrangement, 336 1-day-old Ross 308 broiler chicks were randomly assigned to 4 groups with 7 replicates. Broilers in the control (Ctrl) group were fed a basal diet without extra VitA supplementation. Broilers in the VitA group were fed a basal diet supplemented with 12,000 IU/kg of VitA. Birds in NE and VitA + NE groups were fed corresponding diets and, in addition, co-infected with Eimeria spp. and Clostridium perfringens on days 14 to 20. Samples of the blood, jejunum, spleen and liver were obtained on day 28 for analysis, and meanwhile, lesion scores were also recorded. The results showed that NE challenge increased lesion score in the jejunum and decreased serum glucose, total glyceride, calcium, phosphorus and uric acid levels (p < 0.05). VitA supplementation reduced the levels of serum phosphorus, uric acid and alkaline phosphatase in NE-challenged birds and increased serum low-density lipoprotein content and the activity of aspartate aminotransferase and creatine kinase (p < 0.05). Compared with the Ctrl group, the VitA and NE groups had higher mRNA expression of interferon-γ in the jejunum (p < 0.05). NE challenge up-regulated mRNA expression of interleukin (IL)-13, transforming growth factor-ß4, aldehyde dehydrogenase (RALDH)-2 and RALDH-3 in the jejunum, while VitA supplementation increased jejunal IL-13 mRNA expression and hepatic VitA content, but down-regulated splenic IL-13 mRNA expression (p < 0.05). The VitA + NE group had higher serum prostaglandin E2 levels and the Ctrl group had higher splenic RALDH-3 mRNA expression than that of the other three groups (p < 0.05). NE challenge up-regulated jejunal retinoic acid receptor (RAR)-ß and retinoid X receptor (RXR)-α as well as splenic RAR-α and RAR-ß mRNA expression (p < 0.05). VitA supplementation up-regulated jejunal RAR-ß expression but down-regulated mRNA expression of RXR-α, RXR-γ, signal transducers and activators of transcription (STAT) 5 and STAT6 in the spleen (p < 0.05). Moreover, compared with the Ctrl group, the VitA and NE groups had down-regulated mRNA expression of jejunal and splenic Janus kinase (JAK) 1 (p < 0.05). In conclusion, NE challenge induced jejunal injury and expression of Th2 and Treg cell-related cytokines and enhanced RALDH and RAR/RXR mRNA expression, mainly in the jejunum of broilers. VitA supplementation did not alleviate jejunal injury or Th2 cell-related cytokine expression; however, it improved hepatic VitA deposition and inhibited the expression of RALDH-3, RXR and the JAK/STAT signaling pathway in the spleen of broilers. In short, the present study suggested the modulatory effects of vitamin A on the immune responses and vitamin A metabolism in broiler chickens challenged with necrotic enteritis.

Tannic acid-chelated zinc supplementation alleviates intestinal injury in piglets challenged by porcine epidemic diarrhea virus.

Porcine epidemic diarrhea virus (PEDV) has become a challenging problem in pig industry all over the world, causing significant profit losses. Tannins and organic zinc have been shown to exert protective effects on the intestinal dysfunction caused by endotoxins. However, there is little information on tannic acid-chelated zinc (TAZ) supplementation in the diet of newborn piglets. This study was conducted to determine the effects of TAZ on the intestinal function of piglets infected with PEDV. Thirty-two 7-day-old piglets were randomly allocated to 1 of 4 treatments in a 2 × 2 factorial design consisting of 2 diets (0 or 50 mg/kg BW TAZ) and challenge (saline or PEDV). On day 9 of the trial, 8 pigs per treatment received either sterile saline or PEDV solution at 106 TCID50 (50% tissue culture infectious dose) per pig. Pigs infected with PEDV had greater diarrhea rate and lower average daily gain (ADG) (P < 0.05). PEDV infection decreased plasma D-xylose concentration, most antioxidative enzyme activities in plasma and intestine, as well as the small intestinal villus height (P < 0.05). Plasma diamine oxidase and blood parameters were also affected by PEDV infection. Dietary supplementation with TAZ could ameliorate the PEDV-induced changes in all measured variables (P < 0.05). Moreover, TAZ decreased the concentration of malondialdehyde in plasma, duodenum, jejunum, and colon (P < 0.05). Collectively, our results indicated that dietary TAZ could alleviate PEDV induced damage on intestinal mucosa and antioxidative capacity, and improve the absorptive function and growth in piglets. Therefore, our novel findings also suggest that TAZ, as a new feed additive for neonatal and weaning piglets, has the potential to be an alternative to ZnO.

Trilactic glyceride regulates lipid metabolism and improves gut function in piglets.

Glycerol-lactate esters are energy supplements for exercise, but effects of trilactic glyceride (TLG) on intestinal function and hepatic metabolism are unknown. We found that dietary supplementation with 0.5% TLG to weanling piglets decreased plasma concentrations of low-density lipoprotein and gamma-glutamyl transferase but increased those of D-xylose and high-density lipoprotein. TLG supplementation enhanced mRNA levels for fatty acid synthase (FASN) and SLC27A2 in white adipose tissue; insulin receptor in duodenum; aquaporin-8 in ileum, jejunum and colon; aquaporin-10 in duodenum and ileum; nuclear factor like-2 in jejunum and colon; glutathione S-transferase and phosphoenolpyruvate carboxykinase-1 in intestines; and abundances of claudin-1 and occludin proteins. TLG supplementation decreased mRNA levels for: hepatic hormone-sensitive lipase E, lipoprotein lipase, FASN, insulin-like growth factor-binding protein-3, and SLC27A2; and intestinal lipoprotein lipase, FASN and NADPH oxidase. Furthermore, TLG supplementation enhanced abundances of genus Bifidobacterium, while reducing abundances of family Enterobacteriaceae in ileum, colon and cecum; jejunal caspase-3 protein and diarrhea rate. In conclusion, dietary supplementation with TLG modulated lipid metabolism and alleviated diarrhea by improving intestinal function and regulating intestinal microflora in piglets.

Dietary Supplementation with Trihexanoin Enhances Intestinal Function of Weaned Piglets.

Trihexanoin is a short-chain triglyceride (SCT). Many studies have reported that SCTs play important roles in the maintenance of intestinal epithelial structure and function. The present work was to investigate the effects of trihexanoin on growth performance, carbohydrate and fat metabolism, as well as intestinal morphology and function in weaned piglets. Twenty weaned piglets (21 ± 2 d) were randomly allocated to one of two treatment groups: The control group (basal diet supplemented with 0.5% soya oil); the TH group (basal diet supplemented with 0.5% trihexanoin). Dietary trihexanoin supplementation significantly reduced diarrhea rate; increased the concentrations of LDL, HDL and total protein in plasma; decreased cholesterol concentrations and glutamyl transpeptidase activity in plasma; improved intestinal morphologic structure; altered the mRNA levels and abundances of proteins related to glycogen and fat metabolism, mucosal barrier function, antioxidant capacity and water transport capacity; and altered the community of intestinal microflora. These results indicate that dietary trihexanoin supplementation could reduce diarrhea, regulate carbohydrate and fat metabolism, exert beneficial effects on the intestinal mucosal barrier, protect the intestinal mucosa from injuries, improve intestinal transport and absorption, and enhance antioxidant capacity. In conclusion, dietary supplementation with 0.5% trihexanoin improves the intestinal function and health of weaned piglets.

Effects of dietary coated-oleum cinnamomi supplementation on the immunity and intestinal integrity of broiler chickens.

Oleum cinnamomi (OCM) is increasingly used as a feed additive in animal diets. The aim of this study was to investigate the effects of dietary supplementation with coated-OCM (cOCM) on the immunity and intestinal integrity of broiler chickens. A total of 396 one-day-old chicks were randomly assigned into six groups. The basal diets were supplemented with 50 mg/kg of flavomycin (positive control) as well as 0 (control), 50, 100, 200, and 300 mg/kg of cOCM. Compared with the control, both positive control and cOCM treatments did not improve the growth performance. Serum immunoglobulin (Ig) Y levels were decreased by flavomycin and 50 mg/kg of cOCM treatments (p < 0.05). Dietary cOCM decreased ileal secretory IgA contents at d 21 and commonly down-regulated duodenal and ileal mRNA expression of interleukin (IL)-1ß and IL-8 at d 42 (p < 0.05). The 300 mg/kg of cOCM increased jejunal ratio of villus height to crypt depth and upregulated intestinal claudin-1 expression (p < 0.05). Jejunal (at d 21) and duodenal (at d 42) mucin-2 expression was up and downregulated by both 50 and 300 mg/kg of cOCM, respectively (p < 0.05). In conclusion, dietary cOCM addition helped to maintain noninflammatory states of humoral and mucosal immunity, and improved the intestinal integrity of broiler chickens.

Establishment of a porcine model of indomethacin-induced intestinal injury.

A useful animal model of intestinal injury is pivotal for studying its pathogenesis and developing nutritional interventions (e.g., amino acid supplementation). Here, we propose the use of indomethacin (IDMT) to induce intestinal inflammation in neonatal pigs. Fourteen-day-old piglets fed a milk replacer diet receive intraperitoneal administration of IDMT (5 mg/kg body weight) for 3 consecutive days. On day 4, blood and intestinal samples are obtained for physiological and biochemical analyses. IDMT increases blood DAO activity, I-FABP concentration, neutrophil and eosinophil numbers; intestinal MMP3 mRNA levels, MPO activity, and MDA concentration; but reduces the plasma concentration of citrulline (synthesized exclusively by enterocytes of the small intestine), intestinal GSH-Px activity, and mRNA levels for villin, I-FABP, TRPV6, AQP10, and KCNJ13. Moreover, extensive hemorrhagic spots, thinned intestinal wall, and ulcers in the distal jejunum and ileum are observed in IDMT-challenged piglets. Furthermore, IDMT decreases intestinal villus height and villus surface area in the piglet jejunum. Collectively, this work establishes a porcine model of intestinal injury for designing novel nutritional means to improve gut function in pigs and humans.

Dietary supplementation with an amino acid blend enhances intestinal function in piglets.

The traditionally classified nutritionally non-essential amino acids are now known to be insufficiently synthesized for maximal growth and optimal health in piglets. This study determined the effects of dietary supplementation with an amino acid blend (AAB; glutamate:glutamine:glycine:arginine:N-acetylcysteine = 5:2:2:1:0.5) on piglet growth performance and intestinal functions. Sixteen piglets (24-day-old) were randomly assigned to a corn and soybean meal-based diet supplemented with 0.99% alanine (isonitrogenous control) or 1% AAB. On day 20 of the trial, blood and intestinal tissue samples were obtained from piglets. Compared with the control, AAB supplementation reduced (P < 0.05) diarrhoea incidence; plasma alanine aminotransferase and diamine oxidase activities; intestinal concentrations of hydrogen peroxide, malondialdehyde, and heat shock protein-70, and intestinal mRNA levels for interleukin-1ß, interferon-γ, and chemokine (C-X-C motif) ligand-9; and the numbers of Enterobacterium family, Enterococcus genus and Clostridium coccoides in the colon digesta. Furthermore, AAB supplementation enhanced (P < 0.05): the plasma concentrations of serine, aspartate, glutamate, cysteine, tyrosine, phenylalanine, tryptophan, lysine, arginine, citrulline, ornithine, taurine, and γ-aminobutyric acid; intestinal villus height and surface area, villus height/crypt depth ratio, antioxidative enzyme activities, and mRNA levels for porcine ß-defensin-1, sodium-independent amino acid transporters (b0,+AT and y+LAT1), aquaporin (AQP) 3, AQP8, AQP10, nuclear factor erythroid 2-related factor 2 and glutathione S-transferase omega-2, and protein abundances of AQP3, AQP4, claudin-1, occludin and myxovirus resistance 1; and the numbers of Bifidobacterium genus and Lactobacillus genus in the colon digesta. Collectively, these comprehensive results indicate that dietary AAB supplementation plays an important role in improving piglet growth and intestinal function.

Dietary α-ketoglutarate supplementation improves hepatic and intestinal energy status and anti-oxidative capacity of Cherry Valley ducks.

α-Ketoglutarate (AKG) is an extensively used dietary supplement in human and animal nutrition. The aim of the present study was to investigate effects of dietary AKG supplementation on the energy status and anti-oxidative capacity in liver and intestinal mucosa of Cherry Valley ducks. A total of 80 1-day-old ducks were randomly assigned into four groups, in which ducks were fed basal diets supplemented with 0% (control), 0.5%, 1.0% and 1.5% AKG, respectively. Graded doses of AKG supplementation linearly decreased the ratio of adenosine monophosphate (AMP) to adenosine triphosphate (ATP) in the liver, but increased ATP content and adenylate energy charge (AEC) in a quadratic and linear manner, respectively (P < 0.05). Increasing dietary AKG supplemental levels produced linear positive responses in ATP content and AEC, and negative responses in AMP concentration, the ratio of AMP to ATP and total adenine nucleotide in the ileal mucosa (P < 0.05). All levels of dietary AKG reduced the production of jejunal hydrogen peroxide and hepatic malondialdehyde (P < 0.05). Hepatic and ileal messenger RNA expression of AMP kinase α-1 and hypoxia-inducible factor-1α were linearly up-regulated as dietary AKG supplemental levels increased (P < 0.05). In conclusion, dietary AKG supplementation linearly or quadratically enhanced hepatic and intestinal energy storage and anti-oxidative capacity of Cherry Valley ducks.

N-Acetylcysteine supplementation alleviates intestinal injury in piglets infected by porcine epidemic diarrhea virus.

Porcine epidemic diarrhea virus (PEDV) infects the intestine of young pigs, but effective measures for prevention and treatment are lacking. N-Acetylcysteine (NAC) has been shown to reduce endotoxin-induced intestinal dysfunction. This study was conducted with the PEDV-infected neonatal piglet model to determine the effect of NAC supplementation on intestinal function. Thirty-two 7-day-old piglets were randomly allocated to one of four treatments in a 2 × 2 factorial design consisting of two liquid diets (0 or 50 mg/kg BW NAC supplementation) and oral administration of 0 or 104.5 TCID50 (50% tissue culture infectious dose) PEDV. On day 7 of the trial, half of the pigs (n = 8) in each dietary treatment received either sterile saline or PEDV (Yunnan province strain) solution at 104.5 TCID50 per pig. On day 10 of the trial, D-xylose (0.1 g/kg BW) was orally administrated to all pigs. One hour later, jugular vein blood samples were collected, and then all pigs were killed to obtain the small intestine. PEDV infection increased diarrhea incidence, while reducing ADG. PEDV infection also decreased plasma D-xylose concentration, small intestinal villus height, mucosal I-FABP and villin mRNA levels but increased mucosal MX1 and GCNT3 mRNA levels (P < 0.05). Dietary NAC supplementation ameliorated the PEDV-induced abnormal changes in all the measured variables. Moreover, NAC reduced oxidative stress, as indicated by decreases in plasma and mucosal H2O2 levels. Collectively, these novel results indicate that dietary supplementation with NAC alleviates intestinal mucosal damage and improves the absorptive function of the small intestine in PEDV-infected piglets.

N-Acetylcysteine improves intestinal function in lipopolysaccharides-challenged piglets through multiple signaling pathways.

This study determined whether N-acetylcysteine (NAC) could improve intestinal function through phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR), epithelial growth factor receptor (EGFR), toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB), adenosine 5'-monophosphate-activated protein kinase (AMPK), and type I interferon (IFN) signaling pathways in a piglet model of lipopolysaccharides (LPS) challenge. Thirty-two piglets (24-day-old) were randomly allocated to one of four treatments, with eight replicates per treatment and one piglet per replicate. The experiment consisted of four treatments in a 2 × 2 factorial arrangement with two diets (supplemented with 0 or 500 mg NAC/kg diet) and saline or LPS administration. On day 20 of the trial, piglets in the LPS and LPS + NAC groups were intraperitoneally injected with 0 (saline) or 100 µg LPS/kg BW. Blood samples were obtained at 3 h and intestinal mucosae were collected at 6 h post LPS or saline injection. The growth performance was not affected by dietary NAC. LPS induced intestinal dysfunction, as indicated by: (1) reductions in the small-intestinal glutathione concentrations and plasma D-xylose levels; (2) elevations in plasma diamine oxidase activity, mucosal MMP3 mRNA levels and caspase-3 protein abundance; (3) reduced the activities of the small-intestinal mucosal maltase, sucrase and lactase. The adverse effects of LPS on porcine intestinal function and redox status were mitigated by NAC supplementation through the activation of multiple signaling pathways involving PI3K/Akt/mTOR, EGFR, TLR4/NF-κB, AMPK, and type I IFN. Our findings provide novel mechanisms for beneficial effects of NAC in protecting the intestine from inflammation in animals.

Dietary Supplementation with α-Ketoglutarate Activates mTOR Signaling and Enhances Energy Status in Skeletal Muscle of Lipopolysaccharide-Challenged Piglets.

BACKGROUND: Skeletal muscle undergoes rapid loss in response to inflammation. α-Ketoglutarate (AKG) has been reported to enhance muscle growth in piglets, but the underlying mechanisms are largely unknown. OBJECTIVES: This study tested the hypothesis that dietary AKG supplementation activates mechanistic target of rapamycin (mTOR) signaling and improves skeletal muscle energy metabolism in lipopolysaccharide (LPS)-challenged piglets. METHODS: Forty-eight male piglets (Duroc × Landrace × Yorkshire) were weaned at 21 d of age to a corn- and soybean meal-based diet. After a 3-d period of adaptation, piglets with a mean weight of 7.21 kg were randomly assigned to control, LPS (intraperitoneal administration of 80 µg LPS/kg body weight on days 10, 12, 14, and 16), or LPS plus 1% dietary AKG (LPS+AKG) groups. On day 16, blood samples were collected from 8 piglets/group 3 h after LPS administration. On day 17, piglets were killed to obtain gastrocnemius muscle from 8 piglets/group for biochemical analysis. RESULTS: Compared with the control group, LPS administration increased (P < 0.05) plasma concentrations of globulin (by 14%) and tumor necrosis factor α (by 59%) and the intramuscular ratio of AMP to ATP (by 93%) and abundance of phosphorylated acetyl-coenzyme A carboxylase (ACC) ß protein (by 64%). Compared with the control group, LPS administration reduced (P < 0.05) weight gain (by 15%); plasma concentrations of glutamine (by 20%), glucose (by 23%), insulin, insulin-like growth factor I, and epidermal growth factor; intramuscular concentrations of glutamine (by 27%), ATP (by 12%), ADP (by 22%), and total adenine nucleotides; and intramuscular ratios of phosphorylated mTOR to total mTOR (by 38%) and of phosphorylated 70-kDa ribosomal protein S6 kinase (p70S6K) to total p70S6K (by 39%). These adverse effects of LPS were ameliorated (P < 0.05) by AKG supplementation. CONCLUSIONS: Dietary AKG supplementation activated mTOR signaling, inhibited ACC-ß, and improved energy status in skeletal muscle of LPS-challenged piglets. These results provide a biochemical basis for the use of AKG to enhance piglet growth under inflammatory or practical postweaning conditions.

Dietary supplementation with glutamate precursor α-ketoglutarate attenuates lipopolysaccharide-induced liver injury in young pigs.

There is growing interest in glutamate as a functional amino acid in nutrition and health. This study was conducted to determine whether glutamate precursor α-ketoglutarate (AKG) could alleviate lipopolysaccharide (LPS)-induced liver injury in young pigs. Twenty-four piglets were randomly assigned to the control, LPS, or LPS + AKG group. Piglets in the control and LPS groups were fed a basal diet, whereas piglets in the NAC group were fed the basal diet supplemented with 1 % AKG. On days 10, 12, 14, and 16 of the trial, piglets in the LPS and LPS + AKG groups received intraperitoneal administration of LPS (80 µg/kg BW), whereas piglets in the control group received the same volume of saline. On day 16 of the trial, blood samples were collected 3 h after LPS or saline injection. Twenty-four hours post-administration of LPS or saline (on day 17 of the trial), piglets were killed to obtain liver for analysis. Dietary AKG supplementation alleviated LPS-induced histomorphological abnormalities and mitigated LPS-induced increases in aspartate aminotransferase (AST) activity and AST/ALT ratio (P < 0.05). Compared with the LPS group, dietary supplementation with AKG decreased plasma glutamate concentration, while increasing hepatic concentrations of glutamate, glutamine, leucine, asparagine, lysine, alanine, serine, threonine, valine, and phenylalanine (P < 0.05). LPS challenge dramatically increased concentrations of malondialdehyde and decreased glutathione peroxidase activity in the liver. Additionally, LPS challenge enhanced concentrations of AMP and total protein, as well as RNA/DNA and total protein/DNA ratios, while decreasing hepatic ADP concentrations. These adverse effects of LPS challenge were ameliorated by AKG supplementation. Collectively, dietary AKG supplementation provides a new means to ameliorate LPS-induced liver injury by increasing anti-oxidative capacity and improving energy metabolism in young pigs.

Beneficial roles of dietary oleum cinnamomi in alleviating intestinal injury.

Cinnamon is a traditional herb used for treatment of many human diseases. The most important chemical compounds of the essential oil are cinnamaldehyde and eugenol. Oleum cinnamomi (OCM, cinnamon oil) is increasingly used as a feed additive to animal diets. Beneficial effects of OCM in protecting tissues from inflammation and injury by endogenous and exogenous agents (such as hydrogen peroxide and lipopolysaccharide (LPS)) may result, in part, from its action on regulating amino acid metabolism in cells to favor the synthesis of glutathione (a major low-molecular-weight antioxidant) from cysteine, glycine and glutamate. In support of this notion, results of recent studies indicate that supplementing OCM (50 mg/kg diet) to a corn- and soybean meal-based diet for piglets weaned at 21 days of age enhances intestinal anti-oxidative capacity and reduces the incidence of diarrhea. Additionally, dietary supplementation with OCM ameliorates LPS-induced mucosal barrier dysfunction and mucosal damage in the small intestine. OCM holds great promise for protecting the gut from injury under conditions of inflammation, infections, and oxidative stress.

Dietary supplementation with tributyrin alleviates intestinal injury in piglets challenged with intrarectal administration of acetic acid.

Tributyrin (TBU) is a good dietary source of butyrate and has beneficial effects on the maintenance of normal intestinal morphology. The present study tested the hypothesis that dietary TBU supplementation could alleviate intestinal injury in the acetic acid (ACA)-induced porcine model of colitis. A total of eighteen piglets (25 d old) were randomly allocated to one of three treatment groups (control, ACA and TBU). The control and ACA groups were fed a basal diet and the TBU group was fed the basal diet supplemented with 0·1 % TBU. On day 15 of the trial, under anaesthesia, a soft catheter was inserted into the rectum of piglets (20-25 cm from the anus), followed by administration of either saline (control group) or ACA (10 ml of 10 % ACA solution for ACA and TBU groups). On day 22 of the trial, after venous blood samples were collected, piglets were killed to obtain mid-ileum and mid-colon mucosae. Compared with the control group, the ACA group exhibited an increase (P< 0·05) in lymphocyte counts, creatinine, PGE2, and malondialdehyde concentrations and diamine oxidase and inducible NO synthase activities in the plasma and lymphocyte density in the colon and a decrease in insulin concentrations and glutathione peroxidase activity, ileal villus height:crypt depth ratios and goblet cell numbers in the colon. These adverse effects of ACA were attenuated by TBU supplementation. Moreover, TBU prevented the ACA-induced increase in caspase-3 levels while enhancing claudin-1 protein and epidermal growth factor receptor (EGFR) mRNA expression in the colonic mucosa. Collectively, these results indicate that dietary supplementation with 0·1 % TBU alleviates ACA-induced intestinal injury possibly by inhibiting apoptosis, promoting tight-junction formation and activating EGFR signalling.

Dietary N-acetylcysteine supplementation alleviates liver injury in lipopolysaccharide-challenged piglets.

The present study was carried out to determine whether N-acetylcysteine (NAC) could modulate liver injury in a lipopolysaccharide (LPS)-challenged piglet model. For this purpose, eighteen piglets were randomly assigned to the control, LPS or NAC group. Piglets in the control and LPS groups were fed a basal diet, whereas those in the NAC group were fed the basal diet supplemented with 500 mg/kg NAC. On days 10, 13 and 20 of the trial, the LPS- and NAC-treated piglets were intraperitoneally administered LPS (100 µg/kg body weight), while the control group was administered the same volume of saline. On day 20 of the trial, blood samples were obtained 3 h after LPS or saline injection. On day 21, the piglets were killed to collect liver samples. Dietary NAC supplementation attenuated LPS-induced liver histomorphological abnormalities. Compared with the control group, in the LPS-challenged piglets, the activities of alanine aminotransferase and aspartate aminotransferase and the concentrations of H2O2, TNF-α, IL-6 and PGE2 were dramatically increased in the plasma and the activity of superoxide dismutase in the plasma and that of glutathione peroxidase in the liver were significantly decreased. The LPS challenge also increased the concentration of AMP and the ratio of AMP:ATP, but decreased adenylate energy charges and the levels of ATP and ADP. These adverse effects of the LPS challenge were ameliorated by NAC supplementation. Moreover, NAC inhibited the LPS-induced increases in the abundance of liver heat shock protein 70 and NF-κB proteins. In conclusion, these results suggest that dietary NAC supplementation alleviates LPS-induced liver injury by reducing the secretion of pro-inflammatory cytokines, increasing the antioxidative capacity and improving energy metabolism.

Protective effects of N-acetylcysteine on acetic acid-induced colitis in a porcine model.

BACKGROUND: Ulcerative colitis is a chronic inflammatory disease and involves multiple etiological factors. Acetic acid (AA)-induced colitis is a reproducible and simple model, sharing many characteristics with human colitis. N-acetylcysteine (NAC) has been widely used as an antioxidant in vivo and in vitro. NAC can affect several signaling pathways involving in apoptosis, angiogenesis, cell growth and arrest, redox-regulated gene expression, and inflammatory response. Therefore, NAC may not only protect against the direct injurious effects of oxidants, but also beneficially alter inflammatory events in colitis. This study was conducted to investigate whether NAC could alleviate the AA-induced colitis in a porcine model. METHODS: Weaned piglets were used to investigate the effects of NAC on AA-induced colitis. Severity of colitis was evaluated by colon histomorphology measurements, histopathology scores, tissue myeloperoxidase activity, as well as concentrations of malondialdehyde and pro-inflammatory mediators in the plasma and colon. The protective role of NAC was assessed by measurements of antioxidant status, growth modulator, cell apoptosis, and tight junction proteins. Abundances of caspase-3 and claudin-1 proteins in colonic mucosae were determined by the Western blot method. Epidermal growth factor receptor, amphiregulin, tumor necrosis factor-alpha (TNF-α), and toll-like receptor 4 (TLR4) mRNA levels in colonic mucosae were quantified using the real-time fluorescent quantitative PCR. RESULTS: Compared with the control group, AA treatment increased (P < 0.05) the histopathology scores, intraepithelial lymphocyte (IEL) numbers and density in the colon, myeloperoxidase activity, the concentrations of malondialdehyde and pro-inflammatory mediators in the plasma and colon, while reducing (P < 0.05) goblet cell numbers and the protein/DNA ratio in the colonic mucosa. These adverse effects of AA were partially ameliorated (P < 0.05) by dietary supplementation with NAC. In addition, NAC prevented the AA-induced increase in caspase-3 protein, while stimulating claudin-1 protein expression in the colonic mucosa. Moreover, NAC enhanced mRNA levels for epidermal growth factor and amphiregulin in the colonic mucosa. CONCLUSION: Dietary supplementation with NAC can alleviate AA-induced colitis in a porcine model through regulating anti-oxidative responses, cell apoptosis, and EGF gene expression.

N-acetylcysteine reduces inflammation in the small intestine by regulating redox, EGF and TLR4 signaling.

This study determined whether N-acetylcysteine (NAC) could affect intestinal redox status, proinflammatory cytokines, epidermal growth factor (EGF), EGF receptor (EGFR), Toll-like receptor-4 (TLR4), and aquaporin-8 in a lipopolysaccharide (LPS)-challenged piglet model. Eighteen piglets (35-day-old) were randomly allocated into one of the three treatments (control, LPS and NAC). The control and LPS groups were fed a basal diet, and the NAC group received the basal diet +500 mg/kg NAC. On days 10, 13, and 20 of the trial, the LPS- and NAC-treated piglets received intraperitoneal administration of LPS (100 µg/kg BW), whereas the control group received the same volume of saline. On days 10 and 20, venous blood samples were obtained at 3 h post LPS or saline injection. On day 21 of the trial, piglets were killed to obtain the intestinal mucosa for analysis. Compared with the control group, LPS challenge reduced (P < 0.05) the activities of superoxide dismutase, catalase, and glutathione peroxidase in jejunal mucosae, while increasing (P < 0.05) the concentrations of malondialdehyde, H2O2, O2 (·-) and the ratio of oxidized to reduced glutathione in jejunal mucosae, and concentrations of TNF-α, cortisol, interleukin-6, and prostaglandin E2 in both plasma and intestinal mucosae. These adverse effects of LPS were attenuated (P < 0.05) by NAC supplementation. Moreover, NAC prevented LPS-induced increases in abundances of intestinal HSP70 and NF-κB p65 proteins and TLR4 mRNA. NAC supplementation enhanced plasma EGF concentration and intestinal EGFR mRNA levels. Collectively, these results indicate that dietary NAC supplementation alleviates LPS-induced intestinal inflammation via regulating redox, EGF, and TLR4 signaling.

Protective effects of N-acetylcysteine on intestinal functions of piglets challenged with lipopolysaccharide.

The neonatal small intestine is susceptible to damage by endotoxin, but effective methods for prevention and treatment are lacking. N-acetylcysteine (NAC) is a widely used precursor of L: -cysteine for animal cells and plays an important role in protecting cells against oxidative stress. This study was conducted with the lipopolysaccharide (LPS)-challenged piglet model to determine the effects of NAC on intestinal function. Eighteen piglets were randomly allocated into control, LPS and LPS + NAC groups. The control and LPS groups were fed a corn- and soybean meal-based diet, and the LPS + NAC group was fed the basal diet +500 mg/kg NAC. On days 10, 13 and 20 of the trial, the LPS and LPS + NAC groups received intraperitoneal administration of LPS (100 µg/kg BW), whereas the control piglets received saline. On day 20 of the trial, D-: xylose (0.1 g/kg BW) was orally administrated to all piglets 2 h after LPS or saline injection, and blood samples were collected 1 h thereafter. One hour blood xylose test was used to measure intestinal absorption capacity and mucosal integrity, and diamine oxidase (DAO) was used as a marker of intestinal injury. On day 21 of the trial, pigs were killed to obtain the intestinal mucosa. Compared to the control, LPS challenge reduced (P < 0.05) the concentrations of D-: xylose (a marker of intestinal absorption) in plasma, activities of DAO in the jejunal mucosa, the ratio of villus height to crypt depth in the jejunal mucosa, RNA/DNA and protein/DNA in the jejunal and ileal mucosae, while increasing (P < 0.05) DAO activity in plasma and caspase-3 expression in the intestinal mucosa. The adverse effects of LPS were partially ameliorated (P < 0.05) by NAC supplementation. Moreover, NAC prevented the LPS-induced decrease in claudin-1 and occludin expression in the jejunal and ileal mucosae. Collectively, these results indicate that dietary NAC supplementation alleviates the mucosal damage and improves the absorptive function of the small intestine in LPS-challenged piglets.