Proline supplementation to parenteral nutrition results in greater rates of protein synthesis in the muscle, skin, and small intestine in neonatal Yucatan miniature piglets

Integrated transcriptomics and metabolomics study of embryonic breast muscle of Jiaji ducks

Because number of matured muscle fibers in poultry does not increase after birth, the meat yield is mainly determined during embryogenesis. We previously indicated breast muscle grew rapidly from 18th day after hatching (E18) to E27, and almost stopped from E27 to E34 of Jiaji ducks, while the mechanism is unclear. This study utilized RNA-seq to explore the related genes of muscle development and their relationship with small molecule metabolites at E18, E27 and E34 of Jiaji ducks. Several thousand differentially expressed genes (DEGs) were detected among E18, E27 and E34. DEGs expression profiles included 8 trend maps, among which trend 1 was opposite to and trend 6 was consistent with breast muscle development trend of Jiaji ducks. Through joint analysis between trend 1 of DEGs and trend 1 of differential metabolites (DEMs), protein digestion and absorption pathway stood out. The decrease of COL8A2 gene expression will lead to the decrease of arginine content, which will inhibit the development of breast muscle in embryonic Jiaji duck. Similarly, joint analysis between trend 6 of DEGs and trend 6 of DEMs indicated the increase of GAMT gene expression will cause the increase of proline content, and then promote the development of breast muscle of Jiaji duck in embryonic period. These results will be helpful for further understanding the mechanism of muscle yields of Jiaji ducks.

Deciphering the Therapeutic Role of Lactate in Combating Disuse-Induced Muscle Atrophy: An NMR-Based Metabolomic Study in Mice

Disuse muscle atrophy (DMA) is a significant healthcare challenge characterized by progressive loss of muscle mass and function resulting from prolonged inactivity. The development of effective strategies for muscle recovery is essential. In this study, we established a DMA mouse model through hindlimb suspension to evaluate the therapeutic potential of lactate in alleviating the detrimental effects on the gastrocnemius muscle. Using NMR-based metabolomic analysis, we investigated the metabolic changes in DMA-injured gastrocnemius muscles compared to controls and evaluated the beneficial effects of lactate treatment. Our results show that lactate significantly reduced muscle mass loss and improved muscle function by downregulating Murf1 expression, decreasing protein ubiquitination and hydrolysis, and increasing myosin heavy chain levels. Crucially, lactate corrected perturbations in four key metabolic pathways in the DMA gastrocnemius: the biosynthesis of phenylalanine, tyrosine, and tryptophan; phenylalanine metabolism; histidine metabolism; and arginine and proline metabolism. In addition to phenylalanine-related pathways, lactate also plays a role in regulating branched-chain amino acid metabolism and energy metabolism. Notably, lactate treatment normalized the levels of eight essential metabolites in DMA mice, underscoring its potential as a therapeutic agent against the consequences of prolonged inactivity and muscle wasting. This study not only advances our understanding of the therapeutic benefits of lactate but also provides a foundation for novel treatment approaches aimed at metabolic restoration and muscle recovery in conditions of muscle wasting.

Dietary Methionine Enhances Portal Appearance of Guanidinoacetate and Synthesis of Creatine in Yucatan Miniature Piglets

BACKGROUND

Creatine plays a significant role in energy metabolism and positively impacts anaerobic energy capacity, muscle mass, and physical performance. Endogenous creatine synthesis requires guanidinoacetic acid (GAA) and methionine. GAA can be an alternative to creatine supplements and has been tested as a beneficial feed additive in the animal industry. When pigs are fed GAA with excess methionine, creatine is synthesized without feedback regulation. In contrast, when dietary methionine is limited, creatine synthesis is limited, yet, GAA does not accumulate in plasma, urine, or liver.

OBJECTIVE

We hypothesized that portal GAA appearance requires adequate dietary methionine.

METHODS

Yucatan miniature piglets (17-21 d old; n = 20) were given a 4 h duodenal infusion of complete elemental diets with supplemental GAA plus 1 of 4 methionine concentrations representing either 20%, 80%, 140%, or 200% of the dietary methionine requirement. Arterial and portal blood metabolites were measured along with blood flow to determine mass balance across the gut. [3H-methyl] methionine was infused to measure the methionine incorporation rate into creatine.

RESULTS

GAA balance across the gut was highest in the 200% methionine group, indicating excess dietary methionine enhanced GAA absorption. Creatine synthesis in the liver and jejunum was higher with higher concentrations of methionine, emphasizing that the transmethylation of GAA to creatine depends on sufficient dietary methionine. Hepatic GAA concentration was higher in the 20% methionine group, suggesting low dietary methionine limited GAA conversion to creatine, which led to GAA accumulation in the liver.

CONCLUSIONS

GAA absorption and conversion to creatine require a sufficient amount of methionine, and the supplementation strategies should accommodate this interaction.

Potential nutritional strategies to prevent and reverse sarcopenia in aging process: Role of fish oil-derived ω-3 polyunsaturated fatty acids, wheat oligopeptide and their combined intervention

INTRODUCTION

Nutritional support is potentially considered an essential step to prevent muscle loss and enhance physical function in older adults.

OBJECTIVES

This study aimed to assess the role of potential nutritional strategies, i.e., fish oil-derived ω-3 polyunsaturated fatty acids (PUFAs), wheat oligopeptide and their combined intervention, in preventing and reversing sarcopenia in aging process.

METHODS

One hundred 25-month-old Sprague-Dawley rats were randomly divided into 10 groups, and 10 newly purchased 6-month-old rats were included in young control group (n = 10). Fish oil (200, 400 or 800 mg/kg body weight), wheat oligopeptide (100, 200 or 400 mg/kg body weight), fish oil + wheat oligopeptide (800 + 100, 400 + 200 or 200 + 400 mg/kg body weight) or the equal volume of solvent were administered daily by gavage for 10 weeks. The effects of these interventions on natural aging rats were evaluated.

RESULTS

All intervention groups had a significant increase in muscle mass and grip strength and reduction in perirenal fat weight when compared to the aged control group (P < 0.05). The results of biochemical parameters, magnetic resonance imaging, proteomics and western blot suggested that the combination of wheat oligopeptide and fish oil-derived ω-3 PUFA, especially group WFM 2 (400 + 200 mg/kg body weight fish oil + wheat oligopeptide), was found to be more effective against aging-associated muscle loss than single intervention. Additionally, the interventions ameliorated fatty infiltration, muscle atrophy, and congestion in the intercellular matrix, and inflammatory cell infiltration in muscle tissue. The interventions also improved oxidative stress, anabolism, hormone levels, and inflammatory levels of skeletal muscle.

CONCLUSIONS

The combination of fish oil-derived ω-3 PUFA and wheat oligopeptide was found to be a promising nutritional support to prevent and reverse sarcopenia. The potential mechanism involved the promotion of protein synthesis and muscle regeneration, as well as the enhancement of muscle strength.

Peculiarities in the Amino Acid Composition of Sow Colostrum and Milk, and Their Potential Relevance to Piglet Development

The composition of mother's milk is considered the ideal diet for neonates. This study investigated how conserved or variable the amino acid profile of sow colostrum and milk is throughout lactation, compared with other studies in sows and other species. Twenty-five sows (parity one to seven) from one farm with gestation lengths of 114 to 116 d were sampled on d 0, 3, and 10 after parturition. The total amino acid profile of the samples was analyzed through ion-exchange chromatography, and the results were displayed as the percentage of total amino acid and compared with literature data. Most of the amino acid concentrations in sow milk decreased significantly (p < 0.05) throughout the lactation period, while the amino acid profile generally showed a conserved pattern, especially from d 3 to d 10, and was rather similar across different studies. Glutamine + glutamate was the most abundant amino acid in milk at all sampling moments, accounting for 14-17% of total amino acids. The proportions of proline, valine, and glycine in sow milk nearly accounted for 11%, 7%, and 6% respectively, and were higher compared to human, cow, and goat milk, while the methionine proportion was less than the other three. Compared to the large variations often reported in macronutrient concentrations, the amino acid profile of sow milk in the present study, as well as in others, seems well conserved across the lactation period. Similarities with characteristic differences were also observed between sow milk and piglet body composition, which might reflect the nutrition requirements of preweaning piglets. This study warrants further research exploring the link between the whole amino acid profile and the particular amino acids for suckling piglets and could facilitate insight for optimizing creep feed.

Integration of Transcriptomics and Non-Targeted Metabolomics Reveals the Underlying Mechanism of Skeletal Muscle Development in Duck during Embryonic Stage

Skeletal muscle is an important economic trait in duck breeding; however, little is known about the molecular mechanisms of its embryonic development. Here, the transcriptomes and metabolomes of breast muscle of Pekin duck from 15 (E15_BM), 21 (E21_BM), and 27 (E27_BM) days of incubation were compared and analyzed. The metabolome results showed that the differentially accumulated metabolites (DAMs), including the up-regulated metabolites, l-glutamic acid, n-acetyl-1-aspartylglutamic acid, l-2-aminoadipic acid, 3-hydroxybutyric acid, bilirubin, and the significantly down-regulated metabolites, palmitic acid, 4-guanidinobutanoate, myristic acid, 3-dehydroxycarnitine, and s-adenosylmethioninamine, were mainly enriched in metabolic pathways, biosynthesis of secondary metabolites, biosynthesis of cofactors, protein digestion and absorption, and histidine metabolism, suggesting that these pathways may play important roles in the muscle development of duck during the embryonic stage. Moreover, a total of 2142 (1552 up-regulated and 590 down-regulated), 4873 (3810 up-regulated and 1063 down-regulated), and 2401 (1606 up-regulated and 795 down-regulated) DEGs were identified from E15_BM vs. E21_BM, E15_BM vs. E27_BM and E21_BM vs. E27_BM in the transcriptome, respectively. The significantly enriched GO terms from biological processes were positive regulation of cell proliferation, regulation of cell cycle, actin filament organization, and regulation of actin cytoskeleton organization, which were associated with muscle or cell growth and development. Seven significant pathways, highly enriched by FYN, PTK2, PXN, CRK, CRKL, PAK, RHOA, ROCK, INSR, PDPK1, and ARHGEF, were focal adhesion, regulation of actin cytoskeleton, wnt signaling pathway, insulin signaling pathway, extracellular matrix (ECM)-receptor interaction, cell cycle, and adherens junction, which participated in regulating the development of skeletal muscle in Pekin duck during the embryonic stage. KEGG pathway analysis of the integrated transcriptome and metabolome indicated that the pathways, including arginine and proline metabolism, protein digestion and absorption, and histidine metabolism, were involved in regulating skeletal muscle development in embryonic Pekin duck. These findings suggested that the candidate genes and metabolites involved in crucial biological pathways may regulate muscle development in the Pekin duck at the embryonic stage, and increased our understanding of the molecular mechanisms underlying the avian muscle development.

The Potential of Rhizobacteria to Mitigate Abiotic Stress in Lessertia frutescens

Lessertia frutescens is a multipurpose medicinal plant indigenous to South Africa. The curative ability of the medicinal plant is attributed to its rich phytochemical composition, including amino acids, triterpenoids, and flavonoids. A literature review of some of the phytochemical compounds, particularly amino acids, in L. frutescens shows a steady decrease in concentration over the years. The reduction of the phytochemical compounds and diminishing biological activities may be attributed to drought and salt stress, which South Africa has been grappling with over the years. Canavanine, a phytochemical which is associated with the anticancer activity of L. frutescens, reduced slightly when the plant was subjected to salt stress. Like other legumes, L. frutescens forms a symbiotic relationship with plant-growth-promoting rhizobacteria, which facilitate plant growth and development. Studies employing commercial plant-growth-promoting rhizobacteria to enhance growth and biological activities in L. frutescens have been successfully carried out. Furthermore, alleviation of drought and salt stress in medicinal plants through inoculation with plant growth-promoting-rhizobacteria is well documented and effective. Therefore, this review seeks to highlight the potential of plant-growth-promoting rhizobacteria to alleviate the effect of salt and drought in Lessertia frutescens.

Lysine Dipeptide Enhances Gut Structure and Whole-Body Protein Synthesis in Neonatal Piglets with Intestinal Atrophy

BACKGROUND

Parenteral nutrition (PN) is often a necessity for preterm infants; however, prolonged PN leads to gut atrophy, weakened gut barrier function, and a higher risk of intestinal infections. Peptide transporter-1 (PepT1) is a di- or tripeptide transporter in the gut and, unlike other nutrient transporters, its activity is preserved with the onset of intestinal atrophy from PN. As such, enteral amino acids in the form of dipeptides may be more bioavailable than free amino acids when atrophy is present.

OBJECTIVES

In Yucatan miniature piglets with PN-induced intestinal atrophy, we sought to determine the structural and functional effects of enteral refeeding with lysine as a dipeptide, compared to free L-lysine.

METHODS

Piglets aged 7-8 days were PN-fed for 4 days to induce intestinal atrophy, then were refed with enteral diets with equimolar lysine supplied as lysyl-lysine (Lys-Lys; n = 7), free lysine (n = 7), or Lys-Lys with glycyl-sarcosine (n = 6; to determine whether competitive inhibition of Lys-Lys uptake would abolish PepT1-mediated effects). The diets provided lysine at 75% of the requirement and were gastrically delivered for a total of 18 hours. Whole-body and tissue-specific protein synthesis, as well as indices for gut structure and barrier function, were measured.

RESULTS

The villus height, mucosal weight, and free lysine concentration were higher in the Lys-Lys group compared to the other 2 groups (P < 0.05). Lysyl-lysine led to greater whole-body protein synthesis compared to free lysine (P < 0.05). Mucosal myeloperoxidase activity was lower in the Lys-Lys group (P < 0.05), suggesting less inflammation. The inclusion of glycyl-sarcosine with Lys-Lys abolished the dipeptide effects on whole-body and tissue-specific protein synthesis (P < 0.05), suggesting that improved lysine availability was mediated by PepT1.

CONCLUSIONS

Improved intestinal structure and whole-body protein synthesis suggests that feeding strategies designed to exploit PepT1 may help to avoid adverse effects when enteral nutrition is reintroduced into the compromised guts of neonatal piglets.

Fish oil-based lipid emulsion alleviates parenteral nutrition-associated liver diseases and intestinal injury in piglets

BACKGROUND

Thisstudy aimed to investigate the impact of fish oil-based lipid emulsion (FO) on enterohepatic injuries and intestinal microbiota in piglets of parenteral nutrition (PN).

METHODS

Newborn piglets were divided into three groups, including enteral diet (the controls), PN with 100% FO and PN with medium-chain triglyceride/long-chain triglyceride-based lipid emulsion (MCT/LCT) for 14 days. Serum biochemical indicators, hepatic and intestinal histology, and expression of genes associated with inflammation, oxidative stress, and lipid metabolism were measured. The bile acid (BA) profiles in serum and the taxonomic composition of the gut microbiome in different intestinal segments were analyzed.

RESULTS

Compared with MCT/LCT-piglets, FO reduced inflammation, promoted fatty acid oxidation, and decreased oxidative stress in the liver. In the intestine, FO decreased intestinal inflammation and intestinal permeability, leading to reduced lipopolysaccharide entry into the blood circulation relative to MCT/LCT-piglets. PN groups have dominant contents of Proteobacteria and Bacteroides, whereas the control group have Firmicutes at the phylum level. FO altered the taxonomic compositions of the gut microbiome in different segments, increased the relative abundance of Bacteroidaceae in ileum, and Rikenellaceae and Ruminococcaceae in the colon. FO treatment shifted BA composition ratio in serum and had a lower ratio of secondary BAs to primary BAs.

CONCLUSION

FO alleviates PNLAD and intestinal injury by regulating the homeostasis of BAs' enterohepatic circulation and altering microbiota composition in different intestinal segments.

Serum biochemical parameters and amino acids metabolism are altered in piglets by early-weaning and proline and putrescine supplementations

The study was to investigate the effect of early-weaning stress and proline (Pro) and putrescine (Put) supplementations on serum biochemical parameters and amino acids (AA) metabolism in suckling and post-weaning pigs. Blood and small intestinal mucosa were harvested from suckling piglets at 1, 7, 14, and 21 d of age and piglets on d 1, 3, 5, and 7 after weaning at 14 d of age, as well as from piglets received oral administration of Pro and Put from 1 to 14 d old. In suckling piglets, the serum glucose, albumin and total cholesterol levels were increased (P < 0.05) with increasing age, whereas the serum globulin, urea nitrogen (BUN), alkaline phosphatase (ALP) and aspartate aminotransferase (AST) levels were lowered (P < 0.05). The concentrations of most serum AA and the AA transporters related gene expressions were highest in 7-d-old piglets (P < 0.05), whereas the phosphorylation status of the mammalian target of the rapamycin (mTOR) signaling pathway in the small intestine increased in piglets from 1 to 21 d old (P < 0.05). Weaning at 14 d old increased (P < 0.05) the BUN and triglycerides levels in serum, as well as jejunal solute carrier family 7 member 6 (SLC7A6), ileal SLC36A1 and SLC1A1 mRNA abundances at d 1 or 3 post-weaning. Weaning also inhibited (P < 0.05) the phosphorylation levels of mTOR and its downstream ribosomal protein S6 kinase 1 (S6K1) and 4E-binding protein-1 (4EBP1) in the small intestine of weanling pigs. Oral administration of Put and Pro decreased (P < 0.05) serum ALP levels and increased (P < 0.05) intestinal SLC36A1 and SLC1A1 mRNA abundances and mTOR pathway phosphorylation levels in post-weaning pigs. Pro but not Put treatment enhanced (P < 0.05) serum Pro, arginine (Arg) and glutamine (Gln) concentrations of weaning-pigs. These findings indicated that early-weaning dramatically altered the biochemical blood metabolites, AA profile and intestinal mTOR pathway activity, and Pro and Put supplementations improved the AA metabolism and transportation as well as activated the intestinal mTOR pathway in weanling-pigs. Our study has an important implication for the broad application of Pro and Put in the weaning transition of piglets.

L-Proline Activates Mammalian Target of Rapamycin Complex 1 and Modulates Redox Environment in Porcine Trophectoderm Cells

L-proline (proline) is a key regulator of embryogenesis, placental development, and fetal growth. However, the underlying mechanisms that support the beneficial effects of proline are largely unknown. This study used porcine trophectoderm cell line 2 (pTr2) to investigate the underlying mechanisms of proline in cell proliferation and redox homeostasis. Cells were cultured in the presence of 0, 0.25, 0.50, or 1.0 mmol/L proline for an indicated time. The results showed that 0.5 and 1.0 mmol/L proline enhanced cell viability. These effects of proline (0.5 mmol/L) were accompanied by the enhanced protein abundance of p-mTORC1, p-p70S6K, p-S6, and p-4E-BP1. Additionally, proline dose-dependently enhanced the mRNA expression of proline transporters [solute carrier family (SLC) 6A20, SLC36A1, SLC36A2, SLC38A1, and SLC38A2], elevated proline concentration, and protein abundance of proline dehydrogenase (PRODH). Furthermore, proline addition (0.25 or 0.5 mmol/L) resulted in lower abundance of p-AMPKα when compared with a control. Of note, proline resulted in lower reactive oxygen species (ROS) level, upregulated mRNA expression of the catalytic subunit of glutamate–cysteine ligase (GCLC) and glutathione synthetase (GSS), as well as enhanced total (T)-GSH and GSH concentration when compared with a control. These data indicated that proline activates themTORC1 signaling and modulates the intracellular redox environment via enhancing proline transport.

Modulation of Crustacean Innate Immune Response by Amino Acids and Their Metabolites: Inferences From Other Species

Aquaculture production of crustaceans (mainly shrimp and crabs) has expanded globally, but disease outbreaks and pathogenic infections have hampered production in the last two decades. As invertebrates, crustaceans lack an adaptive immune system and mainly defend and protect themselves using their innate immune system. The immune system derives energy and metabolites from nutrients, with amino acids constituting one such source. A growing number of studies have shown that amino acids and their metabolites are involved in the activation, synthesis, proliferation, and differentiation of immune cells, as well as in the activation of immune related signaling pathways, reduction of inflammatory response and regulation of oxidative stress. Key enzymes in amino acid metabolism have also been implicated in the regulation of the immune system. Here, we reviewed the role played by amino acids and their metabolites in immune-modulation in crustaceans. Information is inferred from mammals and fish where none exists for crustaceans. Research themes are identified and the relevant research gaps highlighted for further studies.

Maternal L-proline supplementation enhances fetal survival, placental development, and nutrient transport in mice†

L-Proline (proline) in amniotic fluid was markedly increased during pregnancy in both pigs and sheep. However, in vivo data to support a beneficial effect of proline on fetal survival are not available. In this study, pregnant C57BL/6J mice were fed a purified diet supplemented with or without 0.50% proline from embryonic day 0.5 (E0.5) to E12.5 or term. Results indicated that dietary supplementation with proline to gestating mice enhanced fetal survival, reproductive performance, the concentrations of proline, arginine, aspartic acid, and tryptophan in plasma and amniotic fluid, while decreasing the concentrations of ammonia and urea in plasma and amniotic fluid. Placental mRNA levels for amino acid transporters, including Slc36a4, Slc38a2, Slc38a4, Slc6a14, and Na+/K+ ATPase subunit-1α (Atp1a1), fatty acid transporter Slc27a4, and glucose transporters Slc2a1 and Slc2a3, were augmented in proline-supplemented mice, compared with the control group. Histological analysis showed that proline supplementation enhanced labyrinth zone in the placenta of mice at E12.5, mRNA levels for Vegf, Vegfr, Nos2, and Nos3, compared with the controls. Western blot analysis showed that proline supplementation increased protein abundances of phosphorylated (p)-mTORC1, p-ribosomal protein S6 kinase (p70S6K), and p-eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1), as well as the protein level of GCN2 (a negative regulator of mTORC1 signaling). Collectively, our results indicate a novel functional role of proline in improving placental development and fetal survival by enhancing placental nutrient transport, angiogenesis, and protein synthesis.

Metabolic and Lipidomic Profiling of Vegetable Juices Fermented with Various Probiotics

Fermented vegetable juices have gained attention due to their various beneficial effects on human health. In this study, we employed gas chromatography-mass spectrometry, direct infusion-mass spectrometry, and liquid chromatography-mass spectrometry to identify useful metabolites, lipids, and carotenoids in vegetable juice (VJ) fermented with Lactobacillus plantarum HY7712, Lactobacillus plantarum HY7715, Lactobacillus helveticus HY7801, and Bifidobacterium animalis ssp. lactis HY8002. A total of 41 metabolites, 24 lipids, and 4 carotenoids were detected in the fermented and non-fermented VJ (control). The lycopene, α-carotene, and β-carotene levels were higher in VJ fermented with L. plantarum strains (HY7712 and HY7715) than in the control. Proline content was also elevated in VJ fermented with HY7715. Uracil, succinic acid, and α-carotene concentration was increased in VJ fermented with HY7801, while glycine and lycopene levels were raised in VJ fermented with HY8002. This study confirmed that each probiotic strain has distinctive characteristics and produces unique changes to metabolic profiles of VJ during fermentation. Our results suggest that probiotic-fermented VJ is a promising functional beverage that contains more beneficial metabolites and carotenoids than commercial non-fermented VJ.

Photoprotection But Not N-acetylcysteine Improves Intestinal Blood Flow and Oxidation Status in Parenterally Fed Piglets

OBJECTIVES

The purpose of the present study was to determine if protecting parenteral nutrition solutions from ambient light and supplementing with N-acetylcysteine (NAC) improves mesenteric blood flow, gut morphology, and oxidative status of parenterally fed neonates.

METHODS

Neonatal Yucatan miniature piglets (n = 23, 7-11 days old) were surgically fitted with central venous catheters and an ultrasonic blood flow probe around the superior mesenteric artery. Piglets were fed continuously for 7 days either light-protected (LP) or light-exposed (LE) complete parenteral nutrition that was enriched with either NAC or alanine (ALA).

RESULTS

There were no differences in body weight or overall gut morphology among groups after 7 days. Plasma concentrations of NAC were greater and total homocysteine lower in NAC- versus ALA-supplemented pigs on day 7 (N-acetylcysteine: 94 vs 7 μmol/L; P < 0.001; homocysteine: 14 versus 21 μmol/L; P < 0.005); plasma total glutathione was not affected. Hepatic lipid peroxidation was reduced by 25% in piglets that received LP parenteral nutrition (P < 0.05). The mesenteric artery blood flow decreased in all pigs between days 2 and 6 (P < 0.001) because of parenteral feeding. Photoprotection alone (LP-ALA) attenuated the decrease in mesenteric blood flow to 66% of baseline on day 6 compared with LE-ALA (37%; P < 0.05) and LP-NAC pigs (43%; P = 0.062); LE-NAC piglets had intermediate reductions in blood flow (55%).

CONCLUSIONS

Photoprotection of parenteral nutrition solutions is a simple, effective method to attenuate decline in blood flow to the gut and hepatic lipid peroxidation, which are both commonly associated with parenteral feeding.

Arterio-venous metabolomics exploration reveals major changes across liver and intestine in the obese Yucatan minipig

Blood circulation mainly aims at distributing the nutrients required for tissue metabolism and collecting safely the by-products of all tissues to be further metabolized or eliminated. The simultaneous study of arterial (A) and venous (V) specific metabolites therefore has appeared to be a more relevant approach to understand and study the metabolism of a given organ. We propose to implement this approach by applying a metabolomics (NMR) strategy on paired AV blood across the intestine and liver on high fat/high sugar (HFHS)-fed minipigs. Our objective was to unravel kinetically and sequentially the metabolic adaptations to early obesity/insulin resistance onset specifically on these two tissues. After two months of HFHS feeding our study of AV ratios of the metabolome highlighted three major features. First, the hepatic metabolism switched from carbohydrate to lipid utilization. Second, the energy demand of the intestine increased, resulting in an enhanced uptake of glutamine, glutamate, and the recruitment of novel energy substrates (choline and creatine). Third, the uptake of methionine and threonine was considered to be driven by an increased intestine turnover to cope with the new high-density diet. Finally, the unique combination of experimental data and modelling predictions suggested that HFHS feeding was associated with changes in tryptophan metabolism and fatty acid β-oxidation, which may play an important role in lipid hepatic accumulation and insulin sensitivity.

Maternal L-proline supplementation during gestation alters amino acid and polyamine metabolism in the first generation female offspring of C57BL/6J mice

We recently reported that dietary supplementation with L-proline (proline) during gestation improved embryonic survival in C57BL/6J mice. The objective of the present study was to test the hypothesis that the effect of maternal proline supplementation on embryonic survival can be carried forward to the first generation female offspring. In the F0 generation, pregnant dams were fed a purified diet supplemented with 0 (control) or 5 g proline/kg diet. The F1 female adult offsprings were bred to fertile males. Fetal survival at embryonic day (E)12.5 and reproductive outcomes at term birth were recorded. The concentrations of amino acids, ammonia, and urea in plasma and amniotic fluid, as well as concentrations of polyamines in placental tissues and amniotic fluid at E12.5 were determined. Results showed that the F1 generation female offspring from proline-supplemented dams had higher (P < 0.05) concentrations of glutamate and taurine in plasma; of putrescine and spermidine in placental tissues; and of glycine, taurine, and spermidine in amniotic fluid at E12.5, as compared with F1 generation female offsprings from dams without proline supplementation. Concentration of proline in the plasma of offspring mice from proline-supplemented dams were lower (P < 0.05), as compared with the control group. No differences in fetal survival, reproductive outcomes, or concentrations of ammonia and urea in plasma and amniotic fluid were observed between the two groups of F1 female offspring. Collectively, our results indicate that the benefits of maternal proline supplementation during gestation on improving embryonic survival and fetal growth in F0 females are not transmitted to their F1 generation females.

l-proline supplementation improves nitric oxide bioavailability and counteracts the blood pressure rise induced by angiotensin II in rats

We evaluated whether l-proline (Pro) supplementation improves redox status and nitric oxide (NO) bioavailability and prevents or delays angiotensin II (AngII)-induced hypertension. Male Sprague-Dawley rats were distributed to four experimental groups: Pro + AngII (Pro-Ang), Pro + Saline (Pro-Sal), Vehicle + AngII (Veh-Ang) and Veh + Saline (Veh-Sal). Pro solution (2 g.kg^-1·day^-1) or water (vehicle) were orally administered, from day 0 to day 21. AngII (200 ng.kg^-1.min^-1) or saline were infused (s.c.) from day 7 to day 21. Systolic blood pressure (SBP) was measured by the tail-cuff method. From day 20-21, animals were kept on metabolic cages for 24h-urine collection. On day 21, urine and blood were collected for further quantification of redox status biomarkers, NO-related markers (urinary nitrates and nitrites, U-NOx; plasma asymmetric dimethylarginine, P-ADMA), metabolic and renal parameters. Pro prevented the AngII-induced SBP rise [mean (95% CI), Day 19: Pro-AngII, 137 (131; 143) vs. Veh-AngII, 157 (151; 163) mm Hg, P < 0.001]. Pro-AngII rats also had increased values of U-NOx, systemic and urinary total antioxidant status (TAS), urinary H₂O₂ and plasma urea, as well as reduced P-ADMA and unaltered urinary isoprostanes. Plasma Pro was inversely correlated with P-ADMA (r = -0.52, p = 0.0009) and positively correlated with urinary TAS (r = 0.55, p = 0.0005) which, in turn, was inversely correlated with P-ADMA (r = -0.56, p = 0.0004). Furthermore, urinary H₂O₂ values decreased across P-ADMA tertiles (p for linear trend = 0.023). These results suggest that Pro reduces P-ADMA levels and improves redox status, thereby increasing NO bioavailability and counteracting the AngII-induced SBP rise. H₂O₂ and TAS modulation by Pro may contribute to the reduced P-ADMA concentration.

Creatine supplementation to total parenteral nutrition improves creatine status and supports greater liver and kidney protein synthesis in neonatal piglets

BackgroundCreatine is not included in commercial pediatric parenteral products; the entire creatine requirement must be met by de novo synthesis from arginine during parenteral nutrition (PN). Poor arginine status is common during PN in neonates, which may compromise creatine accretion. We hypothesized that creatine supplementation will improve creatine status and spare arginine in PN-fed piglets.MethodsPiglets (3-5-day (d) old) were provided PN with or without creatine for 14 d. Tissue concentrations of creatine metabolites and activities of creatine-synthesizing enzymes, as well as tissue protein synthesis rates and liver lipid parameters, were measured.ResultsCreatine provision lowered kidney and pancreas L-arginine:glycine amidinotransferase (AGAT, EC number 2.1.4.1) activities and plasma guanidinoacetic acid (GAA) concentration, suggesting the downregulation of de novo creatine synthesis. Creatine increased plasma creatine concentrations to sow-fed reference levels and increased the creatine concentrations in most tissues, but not in the brain. PN creatine resulted in greater protein synthesis in the liver and the kidney, but not in the pancreas, skeletal muscle, or gut. Creatine supplementation also reduced liver cholesterol concentrations, but not triglyceride or total fat.ConclusionThe addition of creatine to PN may optimize the accretion of creatine and reduce the metabolic burden of creatine synthesis in rapidly growing neonates.

Influence of sublethal doses of acetamiprid and halosulfuron-methyl on metabolites of zebra fish (Brachydanio rerio)

Acetamiprid, a neonicotinoid pesticide, is reported to have adverse sublethal effects on non-target beneficial organisms. Halosulfuron-methyl (HM), one of the most widely used herbicides in agriculture, has high ecotoxicity to aquatic plants and animals. In this study, a GC-MS-based metabolomics approach was used to investigate the toxicity of acetamiprid and HM. The Automated Mass Spectral Deconvolution and Identification System (AMDIS) software program and the retention index method were used to identify 51 metabolites in zebra fish (Brachydanio rerio). Changes in metabolites showed that acetamiprid and HM disturbed amino acid (e.g., leucine, valine, serine, glycine, proline, and alanine) metabolism, the TCA cycle (malic acid and fumaric acid), and the balance of neurotransmitters (glutamic acid, taurine, and glycine). The change in metabolites in the liver, head, and blood indicated that metabolites in the liver were more sensitive than those in the head and blood. Overall, on the basis of the change in metabolites, we identified a potential risk to zebra fish exposed to sublethal doses of acetamiprid and/or HM.

Protein Synthesis in Mucin-Producing Tissues Is Conserved When Dietary Threonine Is Limiting in Piglets

BACKGROUND

The neonatal gastrointestinal tract extracts the majority of dietary threonine on the first pass to maintain synthesis of threonine-rich mucins in mucus. As dietary threonine becomes limiting, this extraction must limit protein synthesis in extraintestinal tissues at the expense of maintaining protein synthesis in mucin-producing tissues.

OBJECTIVE

The objective was to determine the dietary threonine concentration at which protein synthesis is reduced in various tissues.

METHODS

Twenty Yucatan miniature piglets (10 females; mean ± SD age, 15 ± 1 d; mean ± SD weight, 3.14 ± 0.30 kg) were fed 20 test diets with different threonine concentrations, from 0.5 to 6.0 g/100 g total amino acids (AAs; i.e., 20-220% of requirement), and various tissues were analyzed for protein synthesis by administering a flooding dose of [³H]phenylalanine. The whole-body requirement was determined by [1-¹⁴C]phenylalanine oxidation and plasma threonine concentrations.

RESULTS

Breakpoint analysis indicated a whole-body requirement of 2.8-3.0 g threonine/100 g total AAs. For all of the non-mucin-producing tissues as well as lung and colon, breakpoint analyses indicated decreasing protein synthesis rates below the following concentrations (expressed in g threonine/100 g total AAs; mean ± SE): gastrocnemius muscle, 1.76 ± 0.23; longissimus dorsi muscle, 2.99 ± 0.50; liver, 2.45 ± 0.60; kidney, 3.81 ± 0.97; lung, 1.95 ± 0.14; and colon, 1.36 ± 0.29. Protein synthesis in the other mucin-producing tissues (i.e., stomach, proximal jejunum, midjejunum, and ileum) did not change with decreasing threonine concentrations, but mucin synthesis in the ileum and colon decreased over threonine concentrations <4.54 ± 1.50 and <3.20 ± 4.70 g/100 g total AAs, respectively.

CONCLUSIONS

The results of this study illustrate that dietary threonine is preferentially used for protein synthesis in gastrointestinal tissues in piglets. If dietary threonine intake is deficient, then muscle growth and the functions of other tissues are likely compromised at the expense of maintenance of the mucus layer in mucin-producing tissues.

Gross and histological description of the epidermal membrane found on normal neonatal piglets

The structure and composition of fetal and placental tissues vary among different species of placental mammals. Some mammals, including camelids and pigs, possess an epidermal membrane during the fetal stage, called the epithelion, that is absent from other domestic mammals. Because neonatal piglets are a common animal model for many research techniques, it is important that researchers correctly identify this tissue and recognize its lack of pathological consequence when working with fetal and neonatal piglets. Here, the authors describe gross and histological examinations of the epithelion, comparing this tissue with other extra-fetal tissues and coatings.

Dietary requirements of synthesizable amino acids by animals: a paradigm shift in protein nutrition

Amino acids are building blocks for proteins in all animals. Based on growth or nitrogen balance, amino acids were traditionally classified as nutritionally essential or nonessential for mammals, birds and fish. It was assumed that all the “nutritionally nonessential amino acids (NEAA)” were synthesized sufficiently in the body to meet the needs for maximal growth and optimal health. However, careful analysis of the scientific literature reveals that over the past century there has not been compelling experimental evidence to support this assumption. NEAA (e.g., glutamine, glutamate, proline, glycine and arginine) play important roles in regulating gene expression, cell signaling, antioxidative responses, fertility, neurotransmission, and immunity. Additionally, glutamate, glutamine and aspartate are major metabolic fuels for the small intestine to maintain its digestive function and to protect the integrity of the intestinal mucosa. Thus, diets for animals must contain all NEAA to optimize their survival, growth, development, reproduction, and health. Furthermore, NEAA should be taken into consideration in revising the “ideal protein” concept that is currently used to formulate swine and poultry diets. Adequate provision of all amino acids (including NEAA) in diets enhances the efficiency of animal production. In this regard, amino acids should not be classified as nutritionally essential or nonessential in animal or human nutrition. The new Texas A&M University’s optimal ratios of dietary amino acids for swine and chickens are expected to beneficially reduce dietary protein content and improve the efficiency of their nutrient utilization, growth, and production performance.

Effects of amino acids enriched tears substitutes on the cornea of patients with dysfunctional tear syndrome

PURPOSE

To evaluate the effect of aminoacid enriched artificial tears on the ocular surface of patients with dysfunctional tear syndrome (DTS).

METHODS

Forty patients were divided into two groups: group 1 treated for 90 days with sodium hyaluronate (SH) 0.15% 1 drop × 5 times/day; group 2 treated for 90 days with SH 0.15% + aminoacids mixture 1 drop × 5 times/day. Symptom score questionnaire, tear break-up time (TBUT), corneal fluorescein stain, Shirmer's I test and confocal microscopy were performed at baseline and after 30 and 90 days. Confocal images underwent morphometric analysis.

RESULTS

Both treatments improved symptoms after 1 month. Group 2 patients showed at 1 month an improvement of TBUT and corneal stain, maintained throughout the study. Also Shirmer's I test improved after 3 months. In group 1, an improvement of TBUT and corneal stain was observed after 3 months. The morphometric analysis of confocal images demonstrated at month 1 an improvement of nerve tortuosity in group 2; after 3 months both groups showed a significant improvement versus baseline. The epithelium showed, in both groups, a reduction in hyperreflective large cells starting from 1 month; the area of the cells was significantly reduced after 3 months, with a significant higher reduction in group 2. The perineural stromal opacity was significantly increased after 3 months, particularly in group 2.

CONCLUSION

This is the first study addressing corneal changes after amino acids administration in a DTS population. The treatment with amino acids enriched SH can be considered a useful tool in the treatment of DTS.