Intrauterine growth restriction leads to changes in sulfur amino acid metabolism, but not global DNA methylation, in Yucatan miniature piglets

Methionine Modulates the Growth and Development of Heat-Stressed Dermal Papilla Cells via the Wnt/β-Catenin Signaling Pathway

This study furnishes insights into how methionine mitigates heat-stress-induced impairments in hair follicle development in Rex rabbits at the cellular level. Dermal papilla cells from the dorsal skin of Rex rabbits were isolated, cultured in vitro, and divided into six groups, i.e., control (37 °C; 0 mM methionine), heat stress (45 °C; 0 mM methionine), and heat stress + methionine (45 °C; 15 mM, 30 mM, 45 mM, and 60 mM methionine), with six replicates per group. The heat stress groups were exposed to 45 °C, 5% CO2, and 95% humidity for 30 min, followed by recovery at 37 °C, repeated three times over three days. On the third day, samples were collected post-heat stress. The results show that methionine markedly fortified HSP70, MSRA, and SOD expression (p < 0.01); augmented proliferation (p < 0.01); ameliorated cell cycle progression; and lessened apoptosis (p < 0.05). Adding Wnt signaling pathway activators and inhibitors manifested that these effects were associated with diminished β-catenin phosphorylation and aggrandized expression of the Wnt10b, β-catenin (p < 0.001), and LEF/TCF nuclear transcription factors (p < 0.01). Thus, this study demonstrates that methionine regulates the growth and development of heat-stressed hair papilla cells via the Wnt signaling pathway, remitting heat-stress trauma.

Feeding Parenteral Nutrition in the Neonatal Period Programs Dyslipidemia in Adulthood in Yucatan Miniature Pigs

BACKGROUND

Early nutritional challenges can lead to permanent metabolic changes, increasing risk of developing chronic diseases later in life. Total parenteral nutrition (TPN) is a life-saving nutrition regimen, used especially in intrauterine growth-restricted (IUGR) neonates. Early TPN feeding alters metabolism, but whether these alterations are permanent is unclear. Programmed metabolism is likely caused by epigenetic changes due to imbalances of methyl nutrients.

OBJECTIVES

We sought to determine whether feeding TPN in early life would increase risk of developing dyslipidemia in adulthood and whether supplementing the methyl nutrients betaine and creatine to TPN would prevent this development. We also sought to determine whether IUGR exacerbates the effects of neonatal TPN on lipid metabolism in adulthood.

METHODS

Female piglets (n = 32; 7 d old) were used in 4 treatments: 24 normal-weight piglets were randomly assigned to sow-fed (SowFed), standard TPN (TPN-control), and TPN with betaine and creatine (TPN-B+C); 8 IUGR piglets were fed control TPN (TPN-IUGR) as a fourth group. After 2 wk of treatment, all pigs were then fed a standard solid diet. At 8 mo old, central venous catheters were implanted to conduct postprandial fat tolerance tests.

RESULTS

Feeding TPN in the neonatal period led to dyslipidemia in adulthood, as indicated by higher postprandial triglyceride (TG) levels in TPN-control (P < 0.05), compared with SowFed. IUGR piglets were particularly sensitive to neonatal TPN feeding, as TPN-IUGR piglets developed obesity and dyslipidemia in adulthood, as indicated by greater backfat thickness (P < 0.05), higher liver TG (P < 0.05), slower postprandial TG clearance (P < 0.05), and elevated fasting plasma nonhigh-density lipoprotein-cholesterol (P < 0.01), and nonesterified fatty acids (P < 0.001), compared with TPN-control.

CONCLUSIONS

Feeding TPN in early life increases the risk of developing dyslipidemia in adulthood, especially in IUGR neonates; however, methyl nutrient supplementation to TPN did not prevent TPN-induced changes in lipid metabolism.

Enhancing Metabolism and Milk Production Performance in Periparturient Dairy Cattle through Rumen-Protected Methionine and Choline Supplementation

For dairy cattle to perform well throughout and following lactations, precise dietary control during the periparturient phase is crucial. The primary issues experienced by periparturient dairy cows include issues like decreased dry matter intake (DMI), a negative energy balance, higher levels of non-esterified fatty acids (NEFA), and the ensuing inferior milk output. Dairy cattle have always been fed a diet high in crude protein (CP) to produce the most milk possible. Despite the vital function that dairy cows play in the conversion of dietary CP into milk, a sizeable percentage of nitrogen is inevitably expelled, which raises serious environmental concerns. To reduce nitrogen emissions and their production, lactating dairy cows must receive less CP supplementation. Supplementing dairy cattle with rumen-protected methionine (RPM) and choline (RPC) has proven to be a successful method for improving their ability to use nitrogen, regulate their metabolism, and produce milk. The detrimental effects of low dietary protein consumption on the milk yield, protein yield, and dry matter intake may be mitigated by these nutritional treatments. In metabolic activities like the synthesis of sulfur-containing amino acids and methylation reactions, RPM and RPC are crucial players. Methionine, a limiting amino acid, affects the production of milk protein and the success of lactation in general. According to the existing data in the literature, methionine supplementation has a favorable impact on the pathways that produce milk. Similarly, choline is essential for DNA methylation, cell membrane stability, and lipid metabolism. Furthermore, RPC supplementation during the transition phase improves dry matter intake, postpartum milk yield, and fat-corrected milk (FCM) production. This review provides comprehensive insights into the roles of RPM and RPC in optimizing nitrogen utilization, metabolism, and enhancing milk production performance in periparturient dairy cattle, offering valuable strategies for sustainable dairy farming practices.

l-Leucine supplementation reduces growth performance accompanied by changed profiles of plasma amino acids and expression of jejunal amino acid transporters in breast-fed intra-uterine growth-retarded piglets

Previously, we provided an evidence that l-Leucine supplementation facilitates growth performance in suckling piglets with normal birth weight. However, it remains hitherto obscure weather breast-fed piglets displaying intra-uterine growth restriction (IUGR) show a similar effect in response to l-Leucine provision. In this study, 7-d-old sow-reared IUGR piglets were orally administrated with l-Leucine (0, 0·7, 1·4 or 2·1 g/kg BW) twice daily for 2 weeks. Increasing leucine levels hampered the growth performance of suckling IUGR piglets. The average daily gain of IUGR piglets was significantly reduced in 1·4 g/kg BW and 2·1 g/kg BW l-Leucine supplementation groups (P < 0·05). Except for ornithine and glutamine, the plasma concentrations of other amino acids were abated as l-Leucine levels increased (P < 0·05). Leucine supplementation led to reduction in the levels of urea, blood ammonia, blood glucose, TAG and total cholesterol, as well as an elevation in the level of LDL-cholesterol in suckling IUGR piglets (P < 0·05). In addition, 1·4 g/kg BW of l-Leucine enhanced the mRNA expression of ATB0,+, whereas decreased the mRNA abundances of CAT1, y + LAT1, ASCT2 and b0,+AT in the jejunum (P < 0·05). Concomitantly, the jejunum of IUGR piglets in l-Leucine group contains more ATB0,+ and less SNAT2 protein than in the control (P < 0·05). Collectively, l-Leucine supplementation impairs growth performance in breast-fed IUGR piglets, which may be associated with depressed nutritional conditions and alterations in the uptake of amino acids and the expression of amino acid transporters in the small intestine.

Plasma concentrations of per- and polyfluoroalkyl substances are associated with perturbations in lipid and amino acid metabolism

Exposure to per- and polyfluoroalkyl substances (PFAS) through the environment can lead to harmful health outcomes and the development of disease. However, little is known about how PFAS impact underlying biology that contributes to these adverse health effects. The metabolome represents the end product of cellular processes and has been used previously to understand physiological changes that lead to disease. In this study, we investigated whether exposure to PFAS was associated with the global, untargeted metabolome. In a cohort of 459 pregnant mothers and 401 children, we quantified plasma concentrations of six individual PFAS- PFOA, PFOS, PFHXS, PFDEA, and PFNA- and performed plasma metabolomic profiling by UPLC-MS. In adjusted linear regression analysis, we found associations between plasma PFAS and perturbations in lipid and amino acid metabolites in both mothers and children. In mothers, metabolites of 19 lipid pathways and 8 amino acid pathways were significantly associated with PFAS exposure at an FDR<0.05 threshold; in children, metabolites of 28 lipid pathways and 10 amino acid pathways exhibited significant associations at FDR<0.05 with PFAS exposure. Our investigation found that metabolites of the Sphingomyelin, Lysophospholipid, Long Chain Polyunsaturated Fatty Acid (n3 and n6), Fatty Acid- Dicarboxylate, and Urea Cycle showed the most significant associations with PFAS, suggesting these may be particular pathways of interest in the physiological response to PFAS. To our knowledge, this is the first study to characterize associations between the global metabolome and PFAS across multiple periods in the life course to understand impacts on underlying biology, and the findings presented here are relevant in understanding how PFAS disrupt normal biological function and may ultimately give rise to harmful health effects.

Amino Acids in Endoplasmic Reticulum Stress and Redox Signaling

Proteins are the chains of amino acids linked via peptide bonds. In cells, newly synthesized proteins are modified and folded in the endoplasmic reticulum (ER) and matured to be functional proteins before they are transported to other tissues or organs. In addition to protein synthesis, the ER is also a stress-sensing organelle for diverse biological functions, such as calcium storage, lipid synthesis, and cellular metabolism. Nutrient deprivation, accumulation of reactive oxygen species, and other intracellular insults can activate ER stress and unfolded protein response (UPR) to restore homeostasis. Dysfunction of the ER influences cellular physiology and metabolism, and contributes to the pathogenesis of various diseases. Amino acids are the building blocks for proteins of eukaryotic organisms. Both in vivo and in vitro studies have found that amino acids can function as signaling molecules to regulate gene expression, cell proliferation and apoptosis, immune response, and antioxidant capacity in numerous biological processes. Importantly, several lines of studies have indicated that amino acids regulate the abundances of proteins implicated in UPR and the redox state, therefore restoring the intracellular homeostasis. Amino acids play an important role in regulating ER stress and redox homeostasis in animal cells for their survival, growth, and development.

Autoinhibition by Iodide Ion in the Methionine-Iodine Reaction

The methionine–iodine reaction was reinvestigated spectrophotometrically in detail monitoring the absorbance belonging to the isosbestic point of iodine at 468 nm, at T = 25.0 ± 0.1 °C, and at 0.5 M ionic strength in buffered acidic medium. The stoichiometric ratio of the reactants was determined to be 1:1 producing methionine sulfoxide as the lone sulfur-containing product. The direct reaction between methionine and iodine was found to be relatively rapid in the absence of initially added iodide ion, and it can conveniently be followed by the stopped-flow technique. Reduction of iodine eventually leads to the formation of iodide ion that inhibits the reaction making the whole system autoinhibitory with respect to the halide ion. We have also shown that this inhibitory effect appears quite prominently, and addition of iodide ion in the millimole concentration range may result in a rate law where the formal kinetic order of this species becomes −2. In contrast to this, hydrogen ion has just a mildly inhibitory effect giving rise to the fact that iodine is the kinetically active species in the system but not hypoiodous acid. The surprisingly complex kinetics of this simple reaction may readily be interpreted via the initiating rapidly established iodonium-transfer process between the reactants followed by the subsequent hydrolytic decomposition of the short-lived iodinated methionine. A seven-step kinetic model to be able to describe the most important characteristics of the measured kinetic curves is established and discussed in detail.

Sulfur-containing amino acid supplementation to gilts from late pregnancy to lactation altered offspring's intestinal microbiota and plasma metabolites

Maternal nutrition during late pregnancy and lactation is highly involved with the offspring's health status. The study was carried out to evaluate the effects of different ratios of methionine and cysteine (Met/Cys: 46% Met, 51% Met, 56% Met, and 62% Met; maintained with 0.78% of total sulfur-containing amino acids; details in "Materials and methods") supplements in the sows' diet from late pregnancy to lactation on offspring's plasma metabolomics and intestinal microbiota. The results revealed that the level of serum albumin, calcium, iron, and magnesium was increased in the 51% Met group compared with the 46% Met, 56% Met, and 62% Met groups. Plasma metabolomics results indicated that the higher ratios of methionine and cysteine (0.51% Met, 0.56% Met, and 0.62% Met)-supplemented groups enriched the level of hippuric acid, retinoic acid, riboflavin, and δ-tocopherol than in the 46% Met group. Furthermore, the 51% Met-supplemented group had a higher relative abundance of Firmicutes compared with the other three groups (P < 0.05), while the 62% Met-supplemented group increased the abundance of Proteobacteria compared with the other three groups (P < 0.05) in piglets' intestine. These results indicated that a diet consisting with 51% Met is the optimum Met/Cys ratio from late pregnancy to lactation can maintain the offspring's health by improving the serum biochemical indicators and altering the plasma metabolomics profile and intestinal gut microbiota composition, but higher proportion of Met/Cys may increase the possible risk to offspring's health.

Alterations to DNA structure as a cause of expression modifications of selected genes of known intrauterine-growth-restriction-association shared by chosen species - a review

The review aimed at searching for DNA structure markers of epigenetic modifications leading to intrauterine growth restriction (IUGR) in three livestock species, mouse and human. IUGR affects mammals by harming their wellbeing and the profitability of breeding enterprises. Of the livestock species, we chose cow, pig and sheep owing to there being many reports on the epigenetics of IUGR. IUGR investigations in human and mouse are particularly numerous, as we are interested in our own wellbeing and the mouse is a model species. We decided to focus on five genes (Igf2r, Igf2, H19, Peg3 and Mest) of known IUGR association, reported in all of those species. Despite the abundance of papers on IUGR, naturally occurring mutations responsible for epigenetic modifications have been described only in human and cow. The effect of induced DNA structural modifications upon epigenetics has been described in mouse and pig. One paper regarding mouse was chosen from among those describing DNA modifications performed to obtain parthenogenetic progeny. Papers regarding pig parthenogenetic progeny described the epigenetics of genes involved in foetal development, with no interference with the genome structure. No reports on DNA modifications altering IUGR epigenetics in sheep were found. Only environmental effects were studied and we could not conclude from the experiment designs whether the gene setup could affect the expression of involved genes, as different populations were not included or not specified within particular experiments. Apparently, DNA markers of IUGR epigenetics exist. It has been reported that the small number of them, occurring naturally, may result from neglecting existing evidence of such selection or health status forecasting markers.

Are Global DNA methylation and telomere length useful biomarkers for identifying intrauterine growth restricted neonates?

Background: Intrauterine growth restriction (IUGR) is manifested by decreased growth rate of fetus than its normal genetic growth potential. Global DNA methylation is a crucial investigation for identification of epigenetic changes. Epigenetic change regulates Gene transcription, maintenance of genomic stability, and telomere length.Objectives: To investigate whether the global DNA methylation and telomere length are useful for identifying intrauterine growth restriction.Methods: This cohort study was conducted in the Neonatology Department of JIPMER during the period of November 2016 to December 2017. Forty (40) IUGR and forty (40) AGA neonates were recruited. Umbilical cord blood samples were collected at birth. DNA has been separated from the blood samples and using 5-mC DNA ELISA method, the percentage of genomic DNA methylated in these neonates was established. Telomere length (T/S ratio) was measured by using quantitative real time PCR. Data were expressed as a mean ± standard deviation.Results: Genomic DNA methylation varied significantly between IUGR and AGA neonates (IUGR: 3.12 ± 1.24; AGA: 4.40 ± 2.03; p: < .01). There was significant DNA hypo methylation in IUGR neonates. However, telomere length (T/S ratio) was (IUGR: 1.25 ± 0.13; AGA: 1.26 ± 0.22; p: 0.228 (NS)) similar in both groups.Conclusion: Although there is no significant difference in telomere length between IUGR and AGA neonates, global DNA methylation of 3.45 would identify IUGR with a sensitivity and specificity of 69 and 65% respectively.

Artificial intelligence and the analysis of multi-platform metabolomics data for the detection of intrauterine growth restriction

OBJECTIVE

To interrogate the pathogenesis of intrauterine growth restriction (IUGR) and apply Artificial Intelligence (AI) techniques to multi-platform i.e. nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) based metabolomic analysis for the prediction of IUGR.

MATERIALS AND METHODS

MS and NMR based metabolomic analysis were performed on cord blood serum from 40 IUGR (birth weight < 10th percentile) cases and 40 controls. Three variable selection algorithms namely: Correlation-based feature selection (CFS), Partial least squares regression (PLS) and Learning Vector Quantization (LVQ) were tested for their diagnostic performance. For each selected set of metabolites and the panel consists of metabolites common in three selection algorithms so-called overlapping set (OL), support vector machine (SVM) models were developed for which parameter selection was performed busing 10-fold cross validations. Area under the receiver operating characteristics curve (AUC), sensitivity and specificity values were calculated for IUGR diagnosis. Metabolite set enrichment analysis (MSEA) was performed to identify which metabolic pathways were perturbed as a direct result of IUGR in cord blood serum.

RESULTS

All selected metabolites and their overlapping set achieved statistically significant accuracies in the range of 0.78-0.82 for their optimized SVM models. The model utilizing all metabolites in the dataset had an AUC = 0.91 with a sensitivity of 0.83 and specificity equal to 0.80. CFS and OL (Creatinine, C2, C4, lysoPC.a.C16.1, lysoPC.a.C20.3, lysoPC.a.C28.1, PC.aa.C24.0) showed the highest performance with sensitivity (0.87) and specificity (0.87), respectively. MSEA revealed significantly altered metabolic pathways in IUGR cases. Dysregulated pathways include: beta oxidation of very long fatty acids, oxidation of branched chain fatty acids, phospholipid biosynthesis, lysine degradation, urea cycle and fatty acid metabolism.

CONCLUSION

A systematically selected panel of metabolites was shown to accurately detect IUGR in newborn cord blood serum. Significant disturbance of hepatic function and energy generating pathways were found in IUGR cases.

Betaine or folate can equally furnish remethylation to methionine and increase transmethylation in methionine-restricted neonates

Methionine partitioning between protein turnover and a considerable pool of transmethylation precursors is a critical process in the neonate. Transmethylation yields homocysteine, which is either oxidized to cysteine (i.e., transsulfuration), or is remethylated to methionine by folate- or betaine- (from choline) mediated remethylation pathways. The present investigation quantifies the individual and synergistic importance of folate and betaine for methionine partitioning in neonates. To minimize whole body remethylation, 4-8-d-old piglets were orally fed an otherwise complete diet without remethylation precursors folate, betaine and choline (i.e. methyl-deplete, MD-) (n=18). Dietary methionine was reduced from 0.3 to 0.2 g/(kg∙d) on day-5 to limit methionine availability, and methionine kinetics were assessed during a gastric infusion of [¹³C₁]methionine and [²H₃-methyl]methionine. Methionine kinetics were reevaluated 2 d after pigs were rescued with either dietary folate (38 μg/(kg∙d)) (MD + F) (n=6), betaine (235 mg/(kg∙d)) (MD + B) (n=6) or folate and betaine (MD + FB) (n=6). Plasma choline, betaine, dimethylglycine (DMG), folate and cysteine were all diminished or undetectable after 7 d of methyl restriction (P<.05). Post-rescue, plasma betaine and folate concentrations responded to their provision, and homocysteine and glycine concentrations were lower (P<.05). Post-rescue, remethylation and transmethylation rates were~70-80% higher (P<.05), and protein breakdown was spared by 27% (P<.05). However, rescue did not affect transsulfuration (oxidation), plasma methionine, protein synthesis or protein deposition (P>.05). There were no differences among rescue treatments; thus betaine was as effective as folate at furnishing remethylation. Supplemental betaine or folate can furnish the transmethylation requirement during acute protein restriction in the neonate.

Post-ruminal effects of rumen-protected methionine supplementation with low protein diet using long-term simulation and in vitro digestibility technique

Microbial degradation in the rumen and dietary availability of methionine amino acid have been reported as limiting in dairy ruminants. The aim of the present study was to examine the post-ruminal effects of feeding ruminants different concentrations of rumen-protected methionine (RPM) in low crude protein diets using the long-term rumen simulation method (Rusitec) followed by in vitro abomasum and ileum digestibility technique. The experiment contained four treatment groups: (1) high protein, without RPM supplementation (HP); (2) low protein, without RPM supplementation (LP); (3) low protein supplementation with low RPM (LPLM); and (4) low protein supplementation with high RPM (LPHM) mixed per 20 ± 0.04 g basal diet in every fermenter. The results showed that the LPLM and LPHM groups had significantly higher disappearance of crude protein and neutral detergent fiber in the abomasum and ileum than the HP treatment (P < 0.05) and were the same as the LP group (P > 0.05). The proportions of short-chain fatty acids and total volatile fatty acids in the abomasum and ileum were the same between the LPHM and HP groups (P > 0.05); however, the LPLM group was found to be significantly (P < 0.05) lower than the HP group and similar to the LP group (P > 0.05). Rusitec pH before or after changing feed bags and daily ammonia nitrogen production in the abomasum and ileum were non significantly (P > 0.05) different among all groups. In conclusion, RPM supplementation with low crude protein diets promoted post-ruminal digestibility and production of volatile fatty acids.

The Pediatric Methionine Requirement Should Incorporate Remethylation Potential and Transmethylation Demands

The metabolic demand for methionine is great in neonates. Indeed, methionine is the only indispensable sulfur amino acid and is required not only for protein synthesis and growth but is also partitioned to a greater extent to transsulfuration for cysteine and taurine synthesis and to >50 transmethylation reactions that serve to methylate DNA and synthesize metabolites, including creatine and phosphatidylcholine. Therefore, the pediatric methionine requirement must accommodate the demands of rapid protein turnover as well as vast nonprotein demands. Because cysteine spares the methionine requirement, it is likely that the dietary provision of transmethylation products can also feasibly spare methionine. However, understanding the requirement of methionine is further complicated because demethylated methionine can be remethylated by the dietary methyl donors folate and betaine (derived from choline). Intakes of dietary methyl donors are highly variable, which is of particular concern for newborns. It has been demonstrated that many populations have enhanced requirements for these nutrients, and nutrient fortification may exacerbate this phenomenon by selecting phenotypes that increase methyl requirements. Moreover, higher transmethylation rates can limit methyl supply and affect other transmethylation reactions as well as protein synthesis. Therefore, careful investigations are needed to determine how remethylation and transmethylation contribute to the methionine requirement. The purpose of this review is to support our hypothesis that dietary methyl donors and consumers can drive methionine availability for protein synthesis and transmethylation reactions. We argue that nutritional strategies in neonates need to ensure that methionine is available to meet requirements for growth as well as for transmethylation products.

The dynamics of methionine supply and demand during early development

Methionine is an indispensable amino acid that, when not incorporated into protein, is converted into the methyl donor S-adenosylmethionine as entry into the methionine cycle. Following transmethylation, homocysteine is either remethylated to reform methionine or irreversibly trans-sulfurated to form cysteine. Methionine flux to transmethylation and to protein synthesis are both high in the neonate and this review focuses on the dynamics of methionine supply and demand during early development, when growth requires expansion of pools of protein and transmethylation products such as creatine and phosphatidylcholine (PC). The nutrients folate and betaine (derived from choline) donate a methyl group during remethylation, providing an endogenous supply of methionine to meet the methionine demand. During early development, variability in the dietary supply of these methionine cycle-related nutrients can affect both the supply and the demand of methionine. For example, a greater need for creatine synthesis can limit methionine availability for protein and PC synthesis, whereas increased availability of remethylation nutrients can increase protein synthesis if dietary methionine is limiting. Moreover, changes to methyl group availability early in life can lead to permanent changes in epigenetic patterns of DNA methylation, which have been implicated in the early origins of adult disease phenomena. This review aims to summarize how changes in methyl supply and demand can affect the availability of methionine for various functions and highlights the importance of variability in methionine-related nutrients in the infant diet.

Homocysteine metabolism, growth performance, and immune responses in suckling and weanling piglets

Homocysteine (Hcy), an intermediary sulfur AA, is recognized as a powerful prooxidant with deleterious effects on physiological and immune functions. In piglets, there is an acute 10-fold increase of plasma concentrations of homocysteine (pHcy) during the first 2 wk of life. This project aimed to maximize pHcy variations within physiological ranges using typical supplies of folates and vitamin B12 (B12) to sows and piglets. Growth, immune response, and Hcy metabolism of piglets were studied until piglets reached 56 d of age. Third-parity sows were randomly assigned to a 2 × 2 split-plot design with 2 dietary treatments during gestation and lactation, S(-) (1 mg/kg folates and 20 µg/kg B12, n = 15) and S(+) (10-fold S(-) levels, n = 16), and 2 treatments to piglets within each half litter, intramuscular injections (150 µg) of B12 (P(+)) at d 1 and 21 (weaning) and saline (P(-)). Within each litter of 12 piglets, 3 P(+) and 3 P(-) piglets were studied for growth and Hcy metabolism, and the others were studied for immune responses. During lactation, plasma B12 decreased and was transiently greater in S(+) vs. S(-) piglets on d 1 and P(+) vs. P(-) piglets on d 7 (sow treatment × age and piglet treatment × age; P < 0.05). From 14 to 21 d of age, pHcy was 33% lower in S(+)P(+) vs. S(-)P(-) piglets (sow treatment × piglet treatment interaction; P < 0.05). At 56 d of age, hepatic B12 was greater and pHcy was lower for P(+) vs. P(-) piglets (P < 0.05). No treatment effect was observed on growth except for a lower postweaning G:F in S(+)P(-) piglets than in others (sow treatment × piglet treatment interaction; P < 0.05). Positive correlations were observed between pHcy and growth (r > 0.29, P < 0.05) before and after weaning. Antibody responses to ovalbumin and serum tumor necrosis factor-α were not affected by treatments, but postweaning serum IL-8 peaked earlier in S(-)P(-) vs. S(+)P(+) piglets (piglet treatment × age; sow treatment × piglet treatment interaction, P < 0.05). Proliferation of lymphocytes in response to the mitogen concanavalin A tended to be lower in culture media supplemented with sera from S(-) vs. S(+) piglets (P = 0.081) and P(-) vs. P(+) piglets (P = 0.098), and the reduction of response was more marked (P < 0.05) with high (>21 µM) compared to medium (17 to 21 µM) or low (<17 µM) pHcy. In conclusion, the present vitamin supplements to sows and/or piglets produced variations of pHcy that were not apparently harmful for growth performance of piglets. The greater pHcy, particularly prevalent in S(-) and/or P(-) piglets, had negative effects on some indicators of immune responses, suggesting that these young animals may be immunologically more fragile.

Effects on transcriptional regulation and lipid droplet characteristics in the liver of female juvenile pigs after early postnatal feed restriction and refeeding are dependent on birth weight

Epidemiological and experimental data indicate that caloric restriction in early postnatal life may improve liver lipid metabolism in low birth weight individuals.

The present study investigated transcriptional and metabolic responses to low (U) and normal (N) birth weight (d 75, T1) and postnatal feed restriction (R, 60% of controls, d 98, T2) followed by subsequent refeeding until d 131 of age (T3). Liver tissue studies were performed with a total of 42 female pigs which were born by multiparous German landrace sows. Overall, 194 genes were differentially expressed in the liver of U vs. N (T1) animals with roles in lipid metabolism. The total mean area and number of lipid droplets (LD) was about 4.6- and 3.7 times higher in U compared to N. In U, the mean LD size (µm²) was 24.9% higher. 3-week feed restriction reduced total mean area of LDs by 58.3 and 72.7% in U and N, respectively. A functional role of the affected genes in amino acid metabolism was additionally indicated. This was reflected by a 17.0% higher arginine concentration in the liver of UR animals (vs. NR). To evaluate persistency of effects, analyses were also done after refeeding period at T3. Overall, 4 and 22 genes show persistent regulation in U and N animals after 5 weeks of refeeding, respectively. These genes are involved in e.g. processes of lipid and protein metabolism and glucose homeostasis. Moreover, the recovery of total mean LD area in U and N animals back to the previous T1 level was observed. However, when compared to controls, the mean LD size was still reduced by 23.3% in UR, whereas it was increased in NR (+24.7%).

The present results suggest that short-term postnatal feed restriction period programmed juvenile U animals for an increased rate of hepatic lipolysis in later life.

Partitioning of [methyl-3H]methionine to methylated products and protein is altered during high methyl demand conditions in young Yucatan miniature pigs

Methionine is the main source of methyl groups that are partitioned to synthesize various methylated products including creatine, phosphatidylcholine (PC), and methylated DNA. Whether increased methylation of 1 product can divert methionine from protein synthesis or other methylation products was the aim of this experiment. We used an excess of guanidinoacetate (GAA) to synthesize creatine to create a higher demand for available methyl groups in normal-weight (NW) (n = 10) and intrauterine growth-restricted (IUGR) (n = 10) piglets. Anesthetized piglets (15-18 d old) were intraportally infused with either GAA or saline for 2 h. A bolus of l-[methyl-(3)H]methionine was intraportally infused at 1 h, and hepatic metabolites were analyzed for methyl-(3)H incorporation 1 h later. Overall, 50-75% of label was recovered in creatine and PC with negligible amounts in DNA. In both NW and IUGR piglets, excess GAA led to an ≈ 80-120% increase in methyl incorporation into creatine (P < 0.05) with a concomitant decrease by ≈ 75-85% in methyl incorporation into PC (P < 0.05) as well as a 40% decrease in methyl incorporation into protein (P < 0.05), suggesting methyl groups were limited for PC synthesis and that methionine was diverted from protein synthesis. Compared with NW piglets, IUGR piglets had lower methyl incorporation into PC (P < 0.05), but not DNA or protein, suggesting IUGR affects methyl metabolism and could potentially impact lipid metabolism. The partitioning of methionine is sensitive to methyl supply in neonates, which has implications in infant diet composition and growth.