Junqiu Luo

Dietary resveratrol supplementation improves meat quality of finishing pigs through changing muscle fiber characteristics and antioxidative status.

This study investigated the effects of resveratrol (0, 300, 600 mg/kg) on meat quality, muscle fiber characteristics and antioxidative capacity of finishing pigs. The results showed that resveratrol not only increased m. longissimus dorsi (LM) pH(24 h), a*, crude protein and myoglobin content but also decreased L*(24 h), shear force, drip loss, glycolytic potential, as well as backfat depth, LM lactate dehydrogenase activity and mRNA level. Meanwhile, LM total antioxidative capacity, glutathione peroxidase activity and its mRNA level were increased by resveratrol, while malonaldehyde content was decreased. In addition, resveratrol increased myosin heavy chain (MyHC)IIa mRNA level and decreased MyHCIIb mRNA level, along with decreased myofiber cross-sectional area. In conclusion, these results suggest that resveratrol is an effective feed additive to improve pork quality, and the underlying mechanism may be partly due to the changed muscle fiber characteristics and antioxidative capacity induced by resveratrol.

Upregulation of amino acid transporter expression induced by l-leucine availability in L6 myotubes is associated with ATF4 signaling through mTORC1-dependent mechanism

OBJECTIVE Essential amino acids, especially l-leucine, initiate the signaling of the mammalian target of rapamycin complex-1 (mTORC1) and protein synthesis in skeletal muscle. Current information on the relation between amino acid transporter mechanisms and mTORC1 signaling is sparse. The objectives of this study were to determine whether an increase in leucine availability upregulates the gene transcription and translation of amino acid transporters and other amino acid members in an mTORC1-dependent pathway that control amino acid use (general control non-repressed-2 and activating transcription factor-4) and to measure the factors related to protein synthesis and proteolysis. METHODS L6 skeletal muscle cells that had been treated with l-leucine (0.105 g/L) were incubated for 30 min to stimulate the transcription of L-type amino acid transporter-1, CD98, and sodium-coupled neutral amino acid transporter-2 and increase activating transcription factor-4 protein, which is dependent on the mTORC1 signaling pathway. RESULTS A rapid, high level of p70 S6 kinase-1 phosphorylation was detected but was suppressed by rapamycin (P < 0.05). The addition of leucine decreased the atrogin-1 transcription abundance in an insulin-involved manner (P < 0.05), which could not be completely blocked by rapamycin (P = 0.055). CONCLUSIONS Our findings indicate that the mTOR is a component of the nutrient signaling pathway, which regulates system A and L amino acid transporters, the initiation factors involved in mRNA translation, and is downstream of forkhead box-O in L6 myotubes.

Effects of different dietary protein sources on expression of genes related to protein metabolism in growing rats

Protein metabolism is known to be affected by dietary proteins, but the fundamental mechanisms that underlie the changes in protein metabolism are unclear. The aim of the present study was to test the effects of feeding growing rats with balanced diets containing soya protein isolate, zein and casein as the sole protein source on the expression of genes related to protein metabolism responses in skeletal muscle. The results showed that feeding a zein protein diet to the growing rats induced changes in protein anabolic and catabolic metabolism in their gastrocnemius muscles when compared with those fed either the reference protein casein diet or the soya protein isolate diet. The zein protein diet increased not only the mRNA levels and phosphorylation of mammalian target of rapamycin (mTOR), but also the mRNA expression of muscle atrophy F-box (MAFbx)/atrogin-1 and muscle ring finger 1 (MuRF1), as well as the forkhead box-O (FoxO) transcription factors involved in the induction of the E3 ligases. The amino acid profile of proteins seems to control signalling pathways leading to changes in protein synthesis and proteolysis.

Dietary spray-dried chicken plasma improves intestinal barrier function and modulates immune status in weaning piglets.

The objective of this study was to evaluate the effects of dietary addition of spray-dried chicken plasma (SDCP) as a replacement for spray-dried porcine plasma (SDPP) on serum biochemistry, intestinal barrier function, immune parameters, and the expression of intestinal development-related genes in weaning pigs. One hundred and forty-four 25-d-old weaning piglets with BW of 6.43 ± 0.39 kg were randomly allotted to 1 of 4 dietary treatments: 1) CON (basal diet; control), 2) SDPP (containing 5% SDPP), 3) SDPP + SDCP (containing 2.5% SDPP and 2.5% SDCP), and 4) SDCP (containing 5% SDCP). After a 28-d trial, 6 pigs from each treatment were randomly selected to collect serum and intestinal samples. On d 14 after the initiation of the trial, pigs in the SDPP, SDPP + SDCP, and SDCP groups had an increase ( < 0.05) in serum concentrations of total protein and IgG and a decrease ( < 0.05) in activities of alanine aminotransferase and diamine oxidase compared with the CON group. In the jejunum, supplementation with SDPP and SDCP reduced ( < 0.05) the concentration of tumor necrosis factor-α (TNF-α) and upregulated ( < 0.05) the mRNA levels of zonula occludens 1 (ZO-1), zonula occludens 2 (ZO-2), occludin (OCLN), Toll-like receptor 2 (TLR2), glucagon-like peptide 2 (GLP2), and IGF-1 compared with the CON group. In the ileum, feeding SDPP, SDPP + SDCP, and SDCP decreased ( < 0.05) the concentrations of TNF-α and secretory IgA (sIgA) and upregulated ( < 0.05) the mRNA levels of claudin 1 (CLDN-1) and TLR2 compared with feeding CON. However, there were no differences among the SDPP, SDPP + SDCP, and SDCP groups. Furthermore, supplementation with SDCP reduced ( < 0.05) the concentration of IL-10 and upregulated ( < 0.05) the mRNA levels of GLP-2, mucin 2 (MUC2), and trefoil factor family 3 (TFF3) in the ileum compared with feeding CON. Collectively, the current results indicate that dietary addition of SDCP has a beneficial influence on the health condition of weaning pigs by alleviating liver damage, promoting intestinal development, improving intestinal barrier function, and reducing overstimulation of immune response. The efficacy of SDCP is comparable to that of SDPP.

Arginine metabolism and its protective effects on intestinal health and functions in weaned piglets under oxidative stress induced by diquat.

The intestine plays key roles in maintaining body arginine (Arg) homoeostasis. Meanwhile, the intestine is very susceptible to reactive oxygen species. In light of this, the study aimed to explore the effects of Arg supplementation on intestinal morphology, Arg transporters and metabolism, and the potential protective mechanism of Arg supplementation in piglets under oxidative stress. A total of thirty-six weaned piglets were randomly allocated to six groups with six replicates and fed a base diet (0·95 % Arg,) or base diet supplemented with 0·8 % and 1·6 % l-Arg for 1 week, respectively. Subsequently, a challenge test was conducted by intraperitoneal injection of diquat, an initiator of radical production, or sterile saline. The whole trial lasted 11 d. The diquat challenge significantly decreased plasma Arg concentration at 6 h after injection (P<0·05), lowered villus height in the jejunum and ileum (P<0·05) as well as villus width and crypt depth in the duodenum, jejunum and ileum (P<0·05). Oxidative stress significantly increased cationic amino acid transporter (CAT)-1, CAT-2 and CAT-3, mRNA levels (P<0·05), decreased arginase II (ARGII) and inducible nitric oxide synthase mRNA levels, and increased TNF- α mRNA level in the jejunum (P<0·05). Supplementation with Arg significantly decreased crypt depth (P<0·05), suppressed CAT-1 mRNA expression induced by diquat (P<0·05), increased ARGII and endothelial nitric oxide synthase mRNA levels (P<0·05), and effectively relieved the TNF- α mRNA expression induced by diquat in the jejunum (P<0·05). It is concluded that oxidative stress decreased Arg bioavailability and increased expression of inflammatory cytokines in the jejunum, and that Arg supplementation has beneficial effects in the jejunum through regulation of the metabolism of Arg and suppression of inflammatory cytokine expression in piglets.

Differential expression of lipid metabolism-related genes and myosin heavy chain isoform genes in pig muscle tissue leading to different meat quality

The aim of this study was to investigate the variations in meat quality, lipid metabolism-related genes, myosin heavy chain (MyHC) isoform genes and peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) gene mRNA expressions in longissimus dorsi muscle (LM) of two different pig breeds. Six Rongchang and six Landrace barrows were slaughtered at 161 days of age. Subsequently, meat quality traits and gene expression levels in LM were observed. Results showed that Rongchang pigs not only exhibited greater pH, CIE a*24 h and intramuscular fat content but also exhibited lower body weight, carcass weight, dressing percentage, LM area and CIE b*24 h compared with Landrace pigs (P<0.05). Meanwhile, the mRNA expression levels of the lipogenesis (peroxisome proliferator-activated receptor gamma, acetyl-CoA carboxylase and fatty acid synthase) and fatty acid uptake (lipoprotein lipase)-related genes were greater in the Rongchang (P<0.05), whereas the lipolysis (adipose triglyceride lipase and hormone sensitive lipase) and fatty acid oxidation (carnitine palmitoyltransferase-1B)-related genes were better expressed in the Landrace. Moreover, compared with the Landrace, the mRNA expression levels of MyHCI, MyHCIIa and MyHCIIx were greater, whereas the mRNA expression levels of MyHCIIb were lower in the Rongchang pigs (P<0.05). In addition, the mRNA expression levels of PGC-1α were greater in Rongchang pigs than in the Landrace (P<0.05), which can partly explain the differences in MyHC isoform gene expressions between Rongchang and Landrace pigs. Although the small number of samples does not allow to obtain a definitive conclusion, we can suggest that Rongchang pigs possess better meat quality, and the underlying molecular mechanisms responsible for the better meat quality in fatty pigs may be partly due to the higher mRNA expression levels of lipogenesis and fatty acid uptake-related genes, as well as the oxidative and intermediate muscle fibers, and due to the lower mRNA expression levels of lipolysis and fatty acid oxidation-related genes, as well as the glycolytic muscle fibers.

Chlorogenic Acid Improves Intestinal Development via Suppressing Mucosa Inflammation and Cell Apoptosis in Weaned Pigs

Chlorogenic acid (CGA) is a naturally occurring polyphenol in the human diet and plants, exhibiting antioxidant and anti-inflammatory activities. This study was conducted to investigate the effects of CGA on intestinal development and health in weaned pigs. Twenty-four weaned pigs were randomly assigned to two treatments and fed with a basal diet or a basal diet supplemented with 1000 mg/kg CGA. After a 14 d trial, samples were collected. Compared with the control group, CGA supplementation decreased the serum tumor necrosis factor-α, interleukin-6, and interleukin-1βIL-6 concentrations and elevated the serum immunoglobulin G and jejunal secretory immunoglobulin A concentrations. Meanwhile, jejunal villus height, duodenal and jejunal villus width, and jejunal and ileal villus height/crypt depth were increased by CGA. CGA not only decreased the number of duodenal and jejunal cells in the G0G1 phase but also increased the number of jejunal and ileal cells in the S phase. The percentages of late and total apoptotic cells in jejunum and the ratio of B-cell lymphoma-2-assiciated X protein to B-cell lymphoma-2 (Bcl-2) in duodenum and jejunum were also decreased by CGA supplementation. Finally, CGA upregulated the expression level of Bcl-2 in duodenum and jejunum, whereas it downregulated the expression levels of caspase-3 in duodenum and jejunum, caspase-9 in jejunum, as well as Fas in jejunum and ileum. This study suggested that the beneficial effects of CGA on intestinal development and health are partially due to improvement in immune defense and suppression in excessive apoptosis of intestinal epithelial cells in weaned pigs.

Dietary chlorogenic acid improves growth performance of weaned pigs through maintaining antioxidant capacity and intestinal digestion and absorption function

Chlorogenic acid (CGA) is a natural phenolic acid, which is an important component of biologically active dietary phenols isolated from various species. Two experiments were conducted to investigate the effects of CGA on growth performance, antioxidant capacity, nutrient digestibility, diarrhea incidence, intestinal digestion and absorption function, and the expression levels of intestinal digestion and absorption-related genes in weaned pigs. In Exp. 1, 200 weaned pigs were randomly allotted to four dietary treatments and fed with a basal diet or a basal diet supplemented with 250, 500, or 1,000 mg/kg CGA, respectively, in a 14-d trial. Pigs on the 1,000 mg/kg CGA-supplemented group had greater (P < 0.05) G:F compared with those on the control (CON) group. In Exp. 2, 24 weaned pigs were randomly allotted to two groups and fed with a basal diet (CON group) or a basal diet supplemented with 1,000 mg/kg CGA (the optimum does from Exp. 1; CGA group). After a 14-d trial, 8 pigs per treatment were randomly selected to collect serum and intestinal samples. Compared with the CON group, the ADG, G:F, as well as the apparent total tract digestibility of CP, crude fat, and ash were increased (P < 0.05), whereas the diarrhea incidence was decreased (P < 0.05) in the CGA group. Pigs on the CGA group had greater (P < 0.05) serum albumin and IGF-1, and lower (P < 0.05) serum urea nitrogen than pigs on the CON group. Furthermore, dietary CGA supplementation enhanced (P < 0.05) the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) in the serum, the activity of maltase in the jejunum and ileum, as well as the activities of sucrase and alkaline phosphatase (AKP) in the jejunum. The mRNA levels of sodium glucose transport protein-1 (SGLT1) and zinc transporter-1 (ZNT1) in the duodenum and the mRNA levels of SGLT1, glucose transporter-2 (GLUT2), and divalent metal transporter-1 (DMT1) in the jejunum were upregulated (P < 0.05) in pigs fed the CGA diet. These results suggested that dietary CGA supplementation has the potentials to improve the growth performance and decrease the diarrhea incidence of the weaned pigs, possibly through improving the antioxidant capacity and enhancing the intestinal digestion and absorption function.

Effects of Dietary Daidzein Supplementation on Reproductive Performance, Serum Hormones, and Reproductive-Related Genes in Rats

The aim of this study was to investigate the effect of dietary daidzein supplementation on reproductive performance in rats. A total of twenty-four female Sprague–Dawley (SD) rats were randomly allocated to two groups and fed either with a basal diet (CON) or basal diet containing 50 mg/kg daidzein (DAI) from gestation until delivery stage. The results show that daidzein supplementation significantly increased the total litter weight and the total viable newborn weight (p < 0.05). Interestingly, daidzein supplementation acutely elevated the concentrations of serum estrogen, progesterone and insulin-like growth factor-1 (p < 0.01) after the maternal rats’ delivery. The concentrations of serum immunoglobulin A (IgA) and immunoglobulin G (IgG) were also significantly higher in the DAI maternal rats than in the CON maternal rats (p < 0.05). Moreover, daidzein significantly increased the total antioxidant capacity (T-AOC) in maternal rats’ sera and in newborns (p < 0.05) and elevated the concentration of superoxide dismutase (SOD) in both the maternal rats’ sera and their ovaries (p < 0.05). Importantly, daidzein supplementation significantly elevated the expression levels of estrogen receptor β (ERβ) and NR5A2 genes in maternal rats’ ovaries (p < 0.05) and downregulated the expression level of prolactin receptor (PRLR) in newborns (p < 0.05). These results suggest that dietary daidzein supplementation improves reproductive performance and fetal development in rats, which is associated with changes in serum hormones, tissue antioxidant capacity, and expression levels of reproductive-related genes, both in maternal rats and their offspring.

Chlorogenic acid improves intestinal barrier functions by suppressing mucosa inflammation and improving antioxidant capacity in weaned pigs

Intestinal barrier plays key roles in maintaining intestinal homeostasis. Inflammation and oxidative damage can severely destroy the intestinal integrity of mammals. Chlorogenic acid (CGA) is a natural polyphenol present in human diet and plants, possessing potent antioxidant and anti-inflammatory activities. This study was conducted to investigate the protective effects of CGA and its molecular mechanisms on intestinal barrier function in a porcine model. Twenty-four weaned pigs were allotted to two groups and fed with a basal diet or a basal diet containing 1000 mg/kg CGA. The results showed that CGA decreased serum D-lactate and diamine oxidase levels, and enhanced the expression and localization of claudin-1 protein in apical intercellular region of small intestinal epithelium. Interestingly, CGA significantly decreased the mucosa histamine and tryptase contents, as well as the tryptase-positive mast cell counts. Moreover, the expression levels of critical inflammation molecules (interleukin-1β, interleukin-6, tumor necrosis factor-α, and nuclear factor-κB) were down-regulated by CGA in jejunal and ileal mucosa. However, the expression levels of inflammation repressors (suppressor of cytokine signaling 1 and toll-interacting protein) were up-regulated by CGA. Importantly, CGA decreased the malondialdehyde content but elevated glutathione peroxidase and catalase content in duodenal and jejunal mucosa. The expression levels of critical molecules in antioxidant signaling (nuclear factor erythroid-derived 2-related factor 2 and heme oxygenase-1) were elevated by CGA in duodenal and jejunal mucosa. These results suggested that CGA could ameliorate intestinal barrier disruption in weaned pigs, which might be mediated by suppressing the TLR4/NF-κB signaling pathway and activating the Nrf2/HO-1 signaling pathway.