Mechanistic mammalian target of rapamycin (MTOR) cell signaling: effects of select nutrients and secreted phosphoprotein 1 on development of mammalian conceptuses

Endometrial responsiveness to interferon-tau and its association with subsequent reproductive performance in dairy heifers

Our objectives were to evaluate the endometrial responsiveness of dairy heifers to an intrauterine infusion of recombinant bovine interferon-tau (rbIFN-τ) and to associate endometrial responses to rbIFN-τ with subsequent reproductive performance. In Experiments 1 and 2, cyclic heifers were enrolled in a 5-d CIDR Cosynch program for estrous synchronization, and blood sampling and ultrasonography examinations were performed on d 0, 4, 7, 11, and 14 of the estrous cycle. In Experiment 1, heifers were randomly assigned to receive an intrauterine infusion containing 2 µg of rbIFN-τ (rbIFN-τ = 19) or saline (CTRL = 19) into the uterine horn ipsilateral to the corpus luteum (CL) on d 14 of the estrous cycle. Six hours after the infusion, the infused uterine horn was flushed for sampling of the uterine luminal fluid (ULF) for analyses of composition, and the endometrium was biopsied for transcriptomics. In Experiment 2, 100 heifers received an intrauterine infusion of rbIFN-τ, and the same procedures for uterine sample collection described in Experiment 1 were performed. After the intrauterine test, heifers were enrolled in a breeding program and classified as highly fertile (HF; pregnant at first AI) or subfertile (SF; not pregnant at first AI). Statistical analyses were performed using linear regression models, which included the effects of treatment (Experiment 1: CTRL vs. rbIFN-τ) or fertility group (Experiment 2: HF vs. SF) and block of samples. Intrauterine infusion of rbIFN-τ increased the expression of classical interferon-stimulated genes in the endometrium (e.g., ISG15, MX1, OAS2, IRF9, and USP18), and an antiviral response was predicted to be the main downstream effect of the transcriptome changes. In addition, rbIFN-τ increased the abundance of cholesterol, glycerol, and the overall concentration of oxylipins in the ULF. Analysis of endometrial transcriptome between HF and SF heifers revealed important differences in the expression of proteins associated with cell signaling, metabolism, attachment, and migration, with a large representation of genes encoding extracellular matrix proteins. In general, differently expressed genes were expected to be downregulated by IFN-τ but seemed to fail to be downregulated in SF heifers, resulting in higher expression in SF compared with HF heifers. Subfertile heifers had lower concentrations of glycerol and an altered profile of oxylipins in the ULF, with lower abundance of oxylipins derived from arachidonic acid and dihomo-γ-linolenic acid, and greater abundance of oxylipins derived from linoleic acid. Measurements of ovarian function did not differ between groups and, therefore, did not influence the observed results in uterine biology. In conclusion, the endometrial responsiveness to IFN-τ is variable among individuals and associated with subsequent fertility of heifers, indicating that communication between conceptus and endometrium is critical for the uterine receptivity and survival of pregnancy.

Uterine secretome: What do the proteins say about maternal-fetal communication in buffaloes?

The aim was to compare the UF proteomics of pregnant and non-pregnant buffalo during early pregnancy. Forty-four females were submitted to hormonal estrus synchronization and randomly divided into two groups: pregnant (n = 30) and non-pregnant (n = 14). The pregnant group was artificially inseminated and divided into a further two groups: P12 (n = 15) and P18 (n = 15). Conceptus and uterine fluid samples were collected during slaughter at, respectively, 12 and 18 days after insemination. Of all the inseminated females, only eight animals in each group were pregnant, which reduced the sample of the groups to P12 (n = 8) and P18 (n = 8). The non-pregnant group was also re-divided into two groups at the end of synchronization: NP12 (n = 7) and NP18 (n = 7). The UF samples were processed for proteomic analysis. The results were submitted to multivariate and univariate analysis. A total of 1068 proteins were found in the uterine fluid in both groups. Our results describe proteins involved in the conceptus elongation and maternal recognition of pregnancy, and their action was associated with cell growth, endometrial remodeling, and modulation of immune and antioxidant protection, mechanisms necessary for embryonic maintenance in the uterine environment. SIGNIFICANCE: Uterine fluid is a substance synthesized and secreted by the endometrium that plays essential roles during pregnancy in ruminants, contributing significantly to embryonic development. Understanding the functions that the proteins present in the UF perform during early pregnancy, a period marked by embryonic implantation, and maternal recognition of pregnancy is of fundamental importance to understanding the mechanisms necessary for the maintenance of pregnancy. The present study characterized and compared the UF proteome at the beginning of pregnancy in pregnant and non-pregnant buffaloes to correlate the functions of the proteins and the stage of development of the conceptus and unravel their processes in maternal recognition of pregnancy. The proteins found were involved in cell growth and endometrial remodeling, in addition to acting in the immunological protection of the conceptus and performing antioxidant actions necessary for establishing a pregnancy.

Recombinant human chorionic gonadotropin and gonadotropin-releasing hormone agonist differently affect the profile of extracellular vesicle microRNAs in human follicular fluid

PURPOSE

To compare the expression profile of extracellular vesicle microRNAs (EV-miRNAs) derived from follicular fluid after a trigger with recombinant human chorionic gonadotropin (r-hCG) or with a gonadotropin-releasing hormone GnRH agonist (GnRH-a) for final oocyte maturation.

METHODS

A retrospective analysis of a prospective cohort. Women undergoing in vitro fertilization at a tertiary university-affiliated hospital were recruited between 2014 and 2016. EV-miRNAs were extracted from the follicular fluid of a single follicle, and their expression was assessed using TaqMan Open Array®. Genes regulated by EV-miRNAs were analyzed using miRWalk2.0 Targetscan database, DAVID Bioinformatics Resources, Kyoto-Encyclopedia of Genes and Genomes (KEGG), and Gene Ontology (GO).

RESULTS

Eighty-two women were included in the r-hCG trigger group and 9 in the GnRH-a group. Of 754 EV-miRNAs screened, 135 were detected in at least 50% of the samples and expressed in both groups and were further analyzed. After adjusting for multiple testing, 41 EV-miRNAs whose expression levels significantly differed between the two trigger groups were identified. Bioinformatics analysis of the genes regulated by these EV-miRNAs showed distinct pathways between the two triggers, including TGF-beta signaling, cell cycle, and Wnt signaling pathways. Most of these pathways regulate cascades associated with apoptosis, embryo development, implantation, decidualization, and placental development.

CONCLUSIONS

Trigger with GnRH-a or r-hCG leads to distinct EV-miRNAs expression profiles and to downstream biological effects in ovarian follicles. These findings may provide an insight for the increased apoptosis and the lower implantation rates following GnRH-a trigger vs. r-hCG in cases lacking intensive luteal phase support.

The choroid plexus links innate immunity to CSF dysregulation in hydrocephalus

The choroid plexus (ChP) is the blood-cerebrospinal fluid (CSF) barrier and the primary source of CSF. Acquired hydrocephalus, caused by brain infection or hemorrhage, lacks drug treatments due to obscure pathobiology. Our integrated, multi-omic investigation of post-infectious hydrocephalus (PIH) and post-hemorrhagic hydrocephalus (PHH) models revealed that lipopolysaccharide and blood breakdown products trigger highly similar TLR4-dependent immune responses at the ChP-CSF interface. The resulting CSF "cytokine storm", elicited from peripherally derived and border-associated ChP macrophages, causes increased CSF production from ChP epithelial cells via phospho-activation of the TNF-receptor-associated kinase SPAK, which serves as a regulatory scaffold of a multi-ion transporter protein complex. Genetic or pharmacological immunomodulation prevents PIH and PHH by antagonizing SPAK-dependent CSF hypersecretion. These results reveal the ChP as a dynamic, cellularly heterogeneous tissue with highly regulated immune-secretory capacity, expand our understanding of ChP immune-epithelial cell cross talk, and reframe PIH and PHH as related neuroimmune disorders vulnerable to small molecule pharmacotherapy.

Leucine and Arginine Availability Modulate Mouse Embryonic Stem Cell Proliferation and Metabolism

Amino acids are crucial nutrients involved in several cellular and physiological processes, including fertilization and early embryo development. In particular, Leucine and Arginine have been shown to stimulate implantation, as lack of both in a blastocyst culture system is able to induce a dormant state in embryos. The aim of this work was to evaluate the effects of Leucine and Arginine withdrawal on pluripotent mouse embryonic stem cell status, notably, their growth, self-renewal, as well as glycolytic and oxidative metabolism. Our results show that the absence of both Leucine and Arginine does not affect mouse embryonic stem cell pluripotency, while reducing cell proliferation through cell-cycle arrest. Importantly, these effects are not related to Leukemia Inhibitory Factor (LIF) and are reversible when both amino acids are reconstituted in the culture media. Moreover, a lack of these amino acids is related to a reduction in glycolytic and oxidative metabolism and decreased protein translation in mouse embryonic stem cells (mESCs), while maintaining their pluripotent status.

Glucosamine enhances proliferation, barrier, and anti-oxidative functions in porcine trophectoderm cells

Trophectoderm (TE) is the first epithelium that appears during mammalian embryogenesis, and is a polarized transporting single cell layer that comprises the wall of the blastocyst. Previous studies have revealed the functional roles of glucose (Gluc), fructose (Fruc), and glutamine (Gln), which play a positive role in porcine trophectoderm (pTr) cell proliferation and migration, suggesting the importance of nutrients for normal development of the conceptus and implantation. This work was conducted to test the hypothesis that glucosamine (GlcN), which is synthesized from Gln and Fruc-6-phosphate through the hexosamine biosynthesis pathway (HBP), can stimulate proliferation and sustain the barrier and anti-oxidative functions of pTr cells. Cells were treated with 0, 0.25, or 0.5 mmol L^-1 GlcN in the presence or absence of adiquat (DQ) for the indicated time points. The results showed that 0.25 or 0.5 mmol L^-1 GlcN stimulated pTr cell viability and DNA replication compared to the control group. The addition of 0.25 mmol L^-1 GlcN enhanced the phosphorylation of mTOR signaling proteins, which can be inhibited by the inhibitor of phosphatidylinositol 3-kinase (PI3K), LY294002. Transepithelial electrical resistance (TEER) was increased, and paracellular permeability was correspondingly reduced in GlcN treatment. GlcN attenuated DQ-induced cell death and reduced the level of reactive oxygen species (ROS). The decreased TEER values and increased paracellular permeability caused by DQ treatment were also inhibited by GlcN treatment. The addition of 0.5 mmol L^-1 GlcN increased the protein expression of zonula occludens-3 (ZO-3), claudin-3, and claudin-4 in pTr cells, while inhibited the downregulation protein of claudin-1 and claudin-3 brought about by oxidative stress. Collectively, GlcN plays an important role in promoting proliferation and stimulating the mTOR cell signaling pathway, as well as ameliorating oxidative stress and augmenting barrier functions in pTr cells.

Role of reproductive fluids and extracellular vesicles in embryo–maternal interaction during early pregnancy in cattle

The coordinated interaction between the developing embryo and the maternal reproductive tract is essential for the establishment and maintenance of pregnancy in mammals. An early cross-talk is established between the oviduct/uterus and the gametes and embryo. This dialogue will shape the microenvironment in which gamete transport, fertilisation, and early embryonic development occur. Due to the small size of the gametes and the early embryo relative to the volume of the oviductal and uterine lumina, collection of tissue and fluid adjacent to these cells is challenging in cattle. Thus, the combination of in vivo and in vitro models seems to be the most appropriate approach to better understand this fine dialogue. In this respect, the aim of this review is to summarise the recent findings in relation to gamete/embryo-maternal interaction during the pre-elongation period.

L-Arginine Nutrition and Metabolism in Ruminants

L-Arginine (Arg) plays a central role in the nitrogen metabolism (e.g., syntheses of protein, nitric oxide, polyamines, and creatine), blood flow, nutrient utilization, and health of ruminants. This amino acid is produced by ruminal bacteria and is also synthesized from L-glutamine, L-glutamate, and L-proline via the formation of L-citrulline (Cit) in the enterocytes of young and adult ruminants. In pre-weaning ruminants, most of the Cit formed de novo by the enterocytes is used locally for Arg production. In post-weaning ruminants, the small intestine-derived Cit is converted into Arg primarily in the kidneys and, to a lesser extent, in endothelial cells, macrophages, and other cell types. Under normal feeding conditions, Arg synthesis contributes 65% and 68% of total Arg requirements for nonpregnant and late pregnany ewes fed a diet with ~12% crude protein, respectively, whereas creatine production requires 40% and 36% of Arg utilized by nonpregnant and late pregnant ewes, respectively. Arg has not traditionally been considered a limiting nutrient in diets for post-weaning, gestating, or lactating ruminants because it has been assumed that these animals can synthesize sufficient Arg to meet their nutritional and physiological needs. This lack of a full understanding of Arg nutrition and metabolism has contributed to suboptimal efficiencies for milk production, reproductive performance, and growth in ruminants. There is now considerable evidence that dietary supplementation with rumen-protected Arg (e.g., 0.25-0.5% of dietary dry matter) can improve all these production indices without adverse effects on metabolism or health. Because extracellular Cit is not degraded by microbes in the rumen due to the lack of uptake, Cit can be used without any encapsulation as an effective dietary source for the synthesis of Arg in ruminants, including dairy and beef cows, as well as sheep and goats. Thus, an adequate amount of supplemental rumen-protected Arg or unencapsulated Cit is necessary to support maximum survival, growth, lactation, reproductive performance, and feed efficiency, as well as optimum health and well-being in all ruminants.

Impact of donor nutritional balance on the growth and development of mesenchymal stem cells from caprine umbilical cord Wharton´s jelly

Mesenchymal stem cells (MSCs) from the umbilical cord (UC) have aroused considerable interest. However, little is known about the maternal effect on these cells. The aim of this study was to verify the impact of the nutritional status of donor goats on the growth and differentiation of MSCs from the UC. At parturition, 19 goats were grouped based on their low or high body mass index (low BMI, LBMI, n = 9; and high BMI, HBMI, n = 10). UCs were collected during delivery and Wharton's jelly (WJ) fragments cultured. WJ-MSCs were differentiated into osteocytes, adipocytes, chondrocytes, and the population doubling time (PDT) was determined. Samples of WJ-MSCs were also used to verify the expression of the CD90, CD73, CD34, CD45, and CD105 genes. Media used for WJ-MSC primary cultures were analyzed using near-infrared spectroscopy. The lag phase was 7.5 ± 0.6 days and the entire culture took 26.7 ± 1.3 days, with a cell proliferation rate of 8.500 cells/day. The mean PDT from subculture was 30.0 ± 0.7 h. The CD105 gene was sub-expressed in LBMI, and the spectra of the spent media from the second to fourth day of WJ-MSC primary culture were segregated into negative scores by multivariate analysis. We conclude that, in goats, the nutritional balance of the donor did not affect the in vitro growth of MSCs derived from the UC. However, the molecular profile observed in the low BMI group suggests that the use of MSCs for therapeutic purposes should be considered more carefully.

Insights into the lipidome and primary metabolome of the uterus from day 14 cyclic and pregnant sheep†

In ruminants, conceptus elongation requires the endometrium and its secretions. The amino acid, carbohydrate, and protein composition of the uterine lumen during early pregnancy has been defined in sheep; however, a comprehensive understanding of metabolomic changes in the uterine lumen is lacking, particularly with respect to lipids. Here, the lipidome and primary metabolome of the uterine lumen, endometrium, and/or conceptus was determined on day 14 of the estrous cycle and pregnancy. Lipid droplets and select triglycerides were depleted in the endometrium of pregnant ewes. In contrast, select ceramides, diglycerides, and non-esterified fatty acids as well as several phospholipid classes (phosphatidylcholine, phosphatidylinositol, phosphatidylglycerols, and diacylglycerols) were elevated in the uterine lumen of pregnant ewes. Lipidomic analysis of the conceptus revealed that triglycerides are particularly abundant within the conceptus. Primary metabolite analyses found elevated amino acids, carbohydrates, and energy substrates, among others, in the uterine lumen of pregnant ewes. Collectively, this study supports the hypothesis that lipids are important components of the uterine lumen that govern conceptus elongation and growth during early pregnancy.

Role of Dietary Amino Acids and Nutrient Sensing System in Pregnancy Associated Disorders

Defective implantation is related to pregnancy-associated disorders such as spontaneous miscarriage, intrauterine fetal growth restriction and others. Several factors proclaimed to be involved such as physiological, nutritional, environmental and managemental that leads to cause oxidative stress. Overloading of free radicals promotes oxidative stress, and the internal body system could not combat its ability to encounter the damaging effects and subsequently leading to pregnancy-related disorders. During pregnancy, essential amino acids display important role for optimum fetal growth and other necessary functions for continuing fruitful pregnancy. In this context, dietary amino acids have received much attention regarding the nutritional concerns during pregnancy. Arginine, glutamine, tryptophan and taurine play a crucial role in fetal growth, development and survival while ornithine and proline are important players for the regulation of gene expression, protein synthesis and angiogenesis. Moreover, amino acids also stimulate the mammalian target of rapamycin (mTOR) signaling pathway which plays a central role in the synthesis of proteins in placenta, uterus and fetus. This review article explores the significances of dietary amino acids in pregnancy development, regulation of nutrient-sensing pathways such as mTOR, peroxisome proliferator-activated receptors (PPARs), insulin/insulin-like growth factor signaling pathway (IIS) and 5' adenosine monophosphate-activated protein kinase (AMPK) which exhibit important role in reproduction and its related problems. In addition, the antioxidant function of dietary amino acids against oxidative stress triggering pregnancy disorders and their possible outcomes will also be enlightened. Dietary supplementation of amino acids during pregnancy could help mitigate reproductive disorders and thereby improving fertility in animals as well as humans.

New functions for old factors: the role of polyamines during the establishment of pregnancy

Implantation is essential for the establishment of a successful pregnancy, and the preimplantation period plays a significant role in ensuring implantation occurs in a timely and coordinated manner. This requires effective maternal-embryonic signalling, established during the preimplantation period, to synchronise development. Although multiple factors have been identified as present during this time, the exact molecular mechanisms involved are unknown. Polyamines are small cationic molecules that are ubiquitously expressed from prokaryotes to eukaryotes. Despite being first identified over 300 years ago, their essential roles in cell proliferation and growth, including cancer, have only been recently recognised, with new technologies and interest resulting in rapid expansion of the polyamine field. This review provides a summary of our current understanding of polyamine synthesis, regulation and function with a focus on recent developments demonstrating the requirements for polyamines during the establishment of pregnancy up to the implantation stage, in particular the role of polyamines in the control of embryonic diapause and the identification of an alternative pathway for their synthesis in sheep pregnancy. This, along with other novel discoveries, provides new insights into the control of the peri-implantation period in mammals and highlights the complexities that exist in regulating this critical period of pregnancy.

Biochemical characterization of progesterone-induced alterations in bovine uterine fluid amino acid and carbohydrate composition during the conceptus elongation window†

Pregnancy establishment in cattle is contingent on conceptus elongation-a fundamental developmental event coinciding with the time during which most pregnancies fail. Elongation in vivo is directly driven by uterine secretions, indirectly influenced by systemic progesterone concentrations, and has yet to be recapitulated in vitro. To better understand the microenvironment evolved to facilitate this phenomenon, the amino acid and carbohydrate composition of uterine fluid was interrogated using high-throughput metabolomics on days 12, 13, and 14 of the estrous cycle from heifers with normal and high circulating progesterone. A total of 99 biochemicals (79 amino acids and 20 carbohydrates) were consistently identified, of which 31 showed a day by progesterone interaction. Fructose and mannitol/sorbitol did not exhibit a day by progesterone interaction, but displayed the greatest individual fluctuations (P ≤ 0.05) with respective fold increases of 18.39 and 28.53 in high vs normal progesterone heifers on day 12, and increases by 10.70-fold and 14.85-fold in the uterine fluid of normal progesterone animals on day 14 vs day 12. Moreover, enrichment analyses revealed that the phenylalanine, glutathione, polyamine, and arginine metabolic pathways were among the most affected by day and progesterone. In conclusion, progesterone had a largely stabilizing effect on amino acid flux, and identified biochemicals of likely importance to conceptus elongation initiation include arginine, fructose, glutamate, and mannitol/sorbitol.

Hyperandrogenism and insulin resistance induce gravid uterine defects in association with mitochondrial dysfunction and aberrant reactive oxygen species production

Women with polycystic ovary syndrome (PCOS) are at increased risk of miscarriage, which often accompanies the hyperandrogenism and insulin resistance seen in these patients. However, neither the combinatorial interaction between these two PCOS-related etiological factors nor the mechanisms of their actions in the uterus during pregnancy are well understood. We hypothesized that hyperandrogensim and insulin resistance exert a causative role in miscarriage by inducing defects in uterine function that are accompanied by mitochondrial-mediated oxidative stress, inflammation, and perturbed gene expression. Here, we tested this hypothesis by studying the metabolic, endocrine, and uterine abnormalities in pregnant rats after exposure to daily injection of 5α-dihydrotestosterone (DHT; 1.66 mg·kg body wt^-1·day^-1) and/or insulin (6.0 IU/day) from gestational day 7.5 to 13.5. We showed that whereas DHT-exposed and insulin-exposed pregnant rats presented impaired insulin sensitivity, DHT + insulin-exposed pregnant rats exhibited hyperandrogenism and peripheral insulin resistance, which mirrors pregnant PCOS patients. Compared with controls, hyperandrogenism and insulin resistance in the dam were associated with alterations in uterine morphology and aberrant expression of genes responsible for decidualization (Prl8a2, Fxyd2, and Mt1g), placentation (Fcgr3 and Tpbpa), angiogenesis (Flt1, Angpt1, Angpt2, Ho1, Ccl2, Ccl5, Cxcl9, and Cxcl10) and insulin signaling (Akt, Gsk3, and Gluts). Moreover, we observed changes in uterine mitochondrial function and homeostasis (i.e., mitochondrial DNA copy number and the expression of genes responsible for mitochondrial fusion, fission, biogenesis, and mitophagy) and suppression of both oxidative and antioxidative defenses (i.e., reactive oxygen species, Nrf2 signaling, and interactive networks of antioxidative stress responses) in response to the hyperandrogenism and insulin resistance. These findings demonstrate that hyperandrogenism and insulin resistance induce mitochondria-mediated damage and a resulting imbalance between oxidative and antioxidative stress responses in the gravid uterus.

Functional amino acids in the development of the pig placenta

The mammalian placenta is essential for supplying nutrients (e.g., amino acids and water) and oxygen from the mother to fetus and for removing fetal metabolites (e.g., ammonia and CO₂ ) from fetus to mother. Thus, placental growth and development are determinants of fetal survival, growth, and development. Indeed, low birth weight is closely associated with reduced placental growth. Providing gestating gilts or sows with dietary supplementation of arginine and glutamine, increases placental growth (including vascular growth), improves embryonic/fetal growth and survival, and reduces the large variation in birth weight among litters. These two amino acids serve as building blocks for tissue protein as well as substrates for the production of polyamines and nitric oxide, which stimulate DNA and protein synthesis and angiogenesis and vascular growth in the placenta. These recent findings not only greatly advance the field of mammalian amino acid metabolism and nutrition, but also provide practical, mechanism-based methods to enhance reproductive efficiency in swine. These results may also help improve embryonic/fetal survival and growth in other livestock species (e.g., sheep and cattle) and in humans.

Role of progesterone in embryo development in cattle

Progesterone (P4) from the corpus luteum is critical for the establishment and maintenance of pregnancy and plays a major role in regulating endometrial secretions essential for stimulating and mediating changes in conceptus growth and differentiation throughout early pregnancy in ruminants. Numerous studies have demonstrated an association between elevated systemic P4 and acceleration in conceptus elongation. A combination of in vivo and in vitro experiments found that the effects of P4 on conceptus elongation are indirect and mediated through P4-induced effects in the endometrium. Despite effects on elongation, data on the effects of post-insemination supplementation with P4 on pregnancy rates are conflicting. This review highlights the effects of P4 on conceptus development and examines strategies that have been undertaken to manipulate P4 concentrations to increase fertility.

Changes in the metabolome of rats after exposure to arginine and N-carbamylglutamate in combination with diquat, a compound that causes oxidative stress, assessed by 1H NMR spectroscopy

Numerous factors can induce oxidative stress in animal production and lead to growth retardation, disease, and even death. Arginine and N-carbamylglutamate can alleviate the effects of oxidative stress. However, the systematic changes in metabolic biochemistry linked to oxidative stress and arginine and N-carbamylglutamate treatment remain largely unknown. This study aims to examine the effects of arginine and N-carbamylglutamate on rat metabolism under oxidative stress. Thirty rats were randomly divided into three dietary groups (n = 10 each). The rats were fed a basal diet supplemented with 0 (control), 1% arginine, or 0.1% N-carbamylglutamate for 30 days. On day 28, the rats in each treatment were intraperitoneally injected with diquat at 12 mg per kg body weight or sterile solution. Urine and plasma samples were analyzed by metabolomics. Compared with the diquat group, the arginine + diquat group had significantly lower levels of acetamide, alanine, lysine, pyruvate, tyrosine, α-glucose, and β-glucose in plasma; N-carbamylglutamate + diquat had higher levels of 3-hydroxybutyrate, 3-methylhistidine, acetone, allantoin, asparagine, citrate, phenylalanine, trimethylamine-N-oxide, and tyrosine, and lower levels of low density lipoprotein, lipid, lysine, threonine, unsaturated lipid, urea, and very low density lipoprotein (P < 0.05) in plasma. Compared with the diquat group, the arginine + diquat group had significantly higher levels of citrate, creatinine, homogentisate, and α-ketoglutarate while lower levels of acetamide, citrulline, ethanol, glycine, isobutyrate, lactate, malonate, methymalonate, N-acetylglutamate, N-methylnicotinamide, propionate, and β-glucose (P < 0.05) in urine. Compared with the diquat group, the N-carbamylglutamate + diquat group had significantly higher levels of allantoin, citrate, homogentisate, phenylacetylglycine, α-ketoglutarate, and β-glucose while lower levels of acetamide, acetate, acetone, benzoate, citrulline, ethanol, hippurate, lactate, N-acetylglutamate, nicotinamide, ornithine, and trigonelline (P < 0.05) in urine. Overall, these results suggest that arginine and N-carbamylglutamate can alter the metabolome associated with energy metabolism, amino acid metabolism, and gut microbiota metabolism under oxidative stress.

Arginine: New Insights into Growth Performance and Urinary Metabolomic Profiles of Rats

Arginine regulates growth performance, nutrient metabolism and health effects, but the underlying mechanism remains unknown. This study aims to investigate the effect of dietary arginine supplementation on rat growth performance and urinary metabolome through ¹H-NMR spectroscopy. Twenty rats were randomly assigned to two groups supplemented with 0% or 1.0% l-arginine for 4 weeks. Urine samples were analyzed through NMR-based metabolomics. Arginine supplementation significantly increased the urine levels of 4-aminohippurate, acetate, creatine, creatinine, ethanolamine, formate, hippurate, homogentisate, indoxyl sulfate, and phenylacetyglycine. Conversely, arginine decreased the urine levels of acetamide, β-glucose, cirtulline, ethanol, glycine, isobutyrate, lactate, malonate, methymalonate, N-acetylglutamate, N-methylnicotinamide, and propionate. Results suggested that arginine can alter common systemic metabolic processes, including energy metabolism, amino acid metabolism, and gut microbiota metabolism. Moreover, the results also imply a possible physiological role of the metabolism in mediating the arginine supplementation-supported growth of rats.

Changes of serum amino acid profiles by an epidermal growth factor receptor mutation and benzo[a]pyrene in mouse lung tumorigenesis

Studies suggest that gene mutation and carcinogen exposure contribute to lung tumorigenesis including a mutation of epidermal growth factor receptor (EGFR) and exposure to benzo[a]pyrene (BaP). However, the interaction between EGFR mutation and BaP exposure during lung tumorigenesis is unclear. Metabolomics has become an important tool in clinical research and has been utilized to help our understanding of mechanisms and to identify indicators of cancers. This study's aim was to identify the changes in metabolite profiles in mice associated with an EGFR exon 21 deletion and/or BaP treatment-induced lung tumorigenesis. While the EGFR mutation increased the incidence of lung adenoma in transgenic mice (EGFR mutant mice) at 32 weeks of age, exposure to BaP caused the onset of lung tumorigenesis in these mice as early as 16 weeks after exposure. Using a metabolomics strategy involving liquid chromatography-mass spectrometry in conjunction with principal component analysis and confirmation by liquid chromatography triple quadrupole tandem mass spectrometry, we demonstrated that the serum amino acid profiles of these mice were changed. A total of eight amino acid concentrations were lower in EGFR mutant mice than in wild-type mice at 32 weeks of age. Five amino acids were lower in tumor-bearing mice than in non-tumor-bearing EGFR mutant mice at 10th week post-treatment of BaP, namely phenylalanine, tyrosine, alanine, proline, and threonine. Our results suggest that gene mutation and carcinogen exposure-induced lung adenomas share some common mechanisms. Changes in serum amino acid profiles may be early indicators of lung tumorigenesis.

Amino acid composition in eyes from zebrafish (Danio rerio) and sardine (Sardina pilchardus) at the larval stage

A comparative study was performed to identify differences in the amino acid composition of the eyes from zebrafish (Danio rerio) and sardine (Sardina pilchardus) larvae and their link to the environmental adaption of the species. Amino acids in the acidic hydrolysates of eyes from 11 zebrafish and 12 sardine were determined with the use of high-performance liquid chromatography involving precolumn derivatization with ortho-phthalaldehyde. Differences in the content of most amino acids were detected between zebrafish and sardine. These amino acids were aspartate, glutamate, serine, glycine, threonine, arginine, methionine, valine, phenylalanine, isoleucine, leucine and lysine. Of particular note, the percentage of methionine in zebrafish eyes was much higher than that in sardine, whereas the opposite was observed for glutamate and glycine. These results indicate that zebrafish and sardine likely have experienced differences in adaptation to environmental changes. We suggest that the amino acid composition of eyes represents a powerful tool to discriminate between species characterized by different lifestyle and inhabiting different environments.

Analysis of Stage-Specific Gene Expression Profiles in the Uterine Endometrium during Pregnancy in Pigs

The uterine endometrium plays a critical role in regulating the estrous cycle and the establishment and maintenance of pregnancy in mammalian species. Many studies have investigated the expression and function of genes in the uterine endometrium, but the global expression pattern of genes and relationships among genes differentially expressed in the uterine endometrium during gestation in pigs remain unclear. Thus, this study investigated global gene expression profiles using microarray in pigs. Diverse transcriptome analyses including clustering, network, and differentially expressed gene (DEG) analyses were performed to detect endometrial gene expression changes during the different gestation stages. In total, 6,991 genes were found to be differentially expressed by comparing genes expressed on day (D) 12 of pregnancy with those on D15, D30, D60, D90 and D114 of pregnancy, and clustering analysis of detected DEGs distinguished 8 clusters. Furthermore, several pregnancy-related hub genes such as ALPPL2, RANBP17, NF1B, SPP1, and CST6 were discovered through network analysis. Finally, detected hub genes were technically validated by quantitative RT-PCR. These results suggest the complex network characteristics involved in uterine endometrial gene expression during pregnancy and indicate that diverse patterns of stage-specific gene expression and network connections may play a critical role in endometrial remodeling and in placental and fetal development to establish and maintenance of pregnancy in pigs.

Maternal N-Carbamylglutamate Supplementation during Early Pregnancy Enhances Embryonic Survival and Development through Modulation of the Endometrial Proteome in Gilts

BACKGROUND

Early pregnancy loss is a major concern in humans and animals. N-carbamylglutamate (NCG) has been found to enhance embryonic survival during early pregnancy in rats. However, little is known about the key factors in the endometrium involved in the improvement of embryonic implantation and development induced by maternal NCG supplementation.

OBJECTIVES

Our objectives were to investigate whether NCG supplementation during early gestation enhanced embryonic survival and development in gilts and to uncover the related factors using the approach of endometrium proteome analysis with isobaric tags for relative and absolute quantification (iTRAQ).

METHODS

Uteruses and embryos/fetuses were obtained on days 14 and 28 of gestation from gilts fed a basal diet that was or was not supplemented with 0.05% NCG. The iTRAQ-based quantitative proteomics approach was performed to explore the endometrium proteome altered by NCG supplementation.

RESULTS

Maternal NCG supplementation significantly increased the number of total fetuses and live fetuses on day 28 of gestation by 1.32 and 1.29, respectively (P < 0.05), with a significant decrease in embryonic mortality (P < 0.05). iTRAQ results indicated that a total of 59 proteins showed at least 2-fold differences (P < 0.05), including 52 proteins that were present at higher abundance and 7 proteins present at lower abundance in NCG-supplemented gilts. The differentially expressed proteins primarily are involved in cell adhesion, energy metabolism, lipid metabolism, protein metabolism, antioxidative stress, and immune response. On day 14 of gestation, several proteins closely related to embryonic implantation and development, such as integrin-αv, integrin-β3, talin, and endothelial nitric oxide synthase, were upregulated (3.7-, 4.1-, 2.4-, and 5.4-fold increases, respectively) by NCG supplementation.

CONCLUSION

To our knowledge, our results provide the first evidence that altered abundance of the endometrial proteome induced by NCG supplementation is highly associated with the improvement of embryonic survival and development in gilts.

Amino acid metabolism in intestinal bacteria and its potential implications for mammalian reproduction

Reproduction is vital for producing offspring and preserving genetic resources. However, incidences of many reproductive disorders (e.g. miscarriage, intrauterine growth restriction, premature delivery and lower sperm quality) have either increased dramatically or remained at high rates over the last decades. Mounting evidence shows a strong correlation between enteral protein nutrition and reproduction. Besides serving as major nutrients in the diet, amino acids (AA) are signaling molecules in the regulation of diverse physiological processes, ranging from spermatogenesis to oocyte fertilization and to embryo implantation. Notably, the numbers of bacteria in the intestine exceed the numbers of host cells by 10 times. Microbes in the small-intestinal lumen actively metabolize large amounts of dietary AA and, therefore, affect the entry of AA into the portal circulation for whole-body utilization. Changes in the composition and abundance of AA-metabolizing bacteria in the gut during pregnancy, as well as their translocation to the uterus, may alter uterine function and epigenetic modifications of maternal physiology and metabolism, which are crucial for pregnancy recognition and fetal development. Thus, the presence of the maternal gut microbiota and AA metabolites in the intrauterine environments (e.g. endometrium and placenta) and breast milk is likely a unique signature for the programming of the whole-body microbiome and metabolism in both the fetus and infant. Dietary intervention with functional AA, probiotics and prebiotics to alter the abundance and activity of intestinal bacteria may ameliorate or prevent the development of metabolic syndrome, while improving reproductive performance in both males and females as well as their offspring.

Uterine histotroph and conceptus development. I. cooperative effects of arginine and secreted phosphoprotein 1 on proliferation of ovine trophectoderm cells via activation of the PDK1-Akt/PKB-TSC2-MTORC1 signaling cascade

The greatest limitation to reproductive performance in most mammals, including humans, is embryonic mortality, which, in general, claims 20%-40% of the embryos during the peri-implantation period of pregnancy. Both arginine and secreted phosphoprotein 1 (SPP1) are multifunctional molecules that increase significantly in ovine uterine histotroph during early pregnancy. However, little is known about the relationship and underlying mechanisms for synergistic effects of arginine and SPP1, if any, on conceptus (embryo/fetus and associated extraembryonic membranes) development. Therefore, we conducted in vitro experiments using our established ovine trophectoderm cell line (oTr1) isolated from Day 15 ovine conceptuses to determine their proliferative response to individual and synergistic effects of arginine and recombinant SPP1 (rSPP1) that contains an RGD binding sequence. At physiological concentrations, arginine (0.2 mM) stimulated oTr1 cell proliferation 1.7-fold (P < 0.05) at 48 h, whereas rSPP1 (10 ng/ml) had no such effect. However, an additive effect on oTr1 cell proliferation was induced by combination of arginine and SPP1 as compared to the control (2.1-fold increase; P < 0.01), arginine alone (1.3-fold increase; P < 0.05), and rSPP1 alone (1.5-fold increase; P < 0.01). This additive effect was mediated through cooperative activation of the PDK1-Akt/PKB-TSC2-MTORC1 cell signaling cascade. Collectively, results suggest that arginine and SPP1 in histotroph act cooperatively to enhance survival, growth, and development of ovine conceptuses.

Conceptus elongation in ruminants: roles of progesterone, prostaglandin, interferon tau and cortisol

The majority of pregnancy loss in ruminants occurs during the first three weeks after conception, particularly during the period of conceptus elongation that occurs prior to pregnancy recognition and implantation. This review integrates established and new information on the biological role of ovarian progesterone (P4), prostaglandins (PGs), interferon tau (IFNT) and cortisol in endometrial function and conceptus elongation. Progesterone is secreted by the ovarian corpus luteum (CL) and is the unequivocal hormone of pregnancy. Prostaglandins (PGs) and cortisol are produced by both the epithelial cells of the endometrium and the trophectoderm of the elongating conceptus. In contrast, IFNT is produced solely by the conceptus trophectoderm and is the maternal recognition of pregnancy signal that inhibits production of luteolytic pulses of PGF_2α by the endometrium to maintain the CL and thus production of P4. Available results in sheep support the idea that the individual, interactive, and coordinated actions of P4, PGs, IFNT and cortisol regulate conceptus elongation and implantation by controlling expression of genes in the endometrium and/or trophectoderm. An increased knowledge of conceptus-endometrial interactions during early pregnancy in ruminants is necessary to understand and elucidate the causes of infertility and recurrent early pregnancy loss and provide new strategies to improve fertility and thus reproductive efficiency.

Osteopontin is expressed in the oviduct and promotes fertilization and preimplantation embryo development of mouse

Osteopontin (OPN) is a multifunctional phosphoprotein that is detected in various tissues, including male and female reproductive tracts. In this study, we evaluated OPN expression in mouse oviducts during the estrus cycle, and at days 1–5 of pregnancy and pseudopregnancy by reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry. The mice oocytes, sperm and embryos were treated with different concentrations of anti-OPN antibody in vitro to detect the function of OPN in fertilization and preimplantation embryo development. OPN mRNA and protein expression in mouse oviducts were cyclic dependent throughout the estrous cycle, which was highest at estrous and lowest at diestrous. Such a phenomenon was consistent with the change in estrogen level in mice. The expression levels of OPN in mice oviduct of normal pregnancy and pseudopregnancy were significantly different, which indicated that OPN expression in mouse oviducts was depend on estrogen and preimplantation embryo. Furthermore, anti-OPN antibody treatment could reduce the rates of fertilization, cleavage and blastocyst formation in vitro in a dose-dependent way. Overall, our results indicated that the expression of OPN in mouse oviducts during the estrous cycle and early pregnancy is likely regulated by estrogen and the embryo, and OPN may play a vital role in oocyte fertilization and preimplantation embryo development.

Triennial Reproduction Symposium: deficiencies in the uterine environment and failure to support embryonic development

Pregnancy failure in livestock can result from failure to fertilize the oocyte or embryonic loss during gestation. The focus of this review is on cattle and factors affecting and mechanisms related to uterine insufficiency for pregnancy. A variety of factors contribute to embryonic loss and it may be exacerbated in certain animals, such as high-producing lactating dairy cows, and in some cattle in which estrous synchronization and timed AI was performed, due to reduced concentrations of reproductive steroids. Recent research in beef cattle induced to ovulate immature follicles and in lactating dairy cows indicates that deficient uterine function is a major factor responsible for infertility in these animals. Failure to provide adequate concentrations of estradiol before ovulation results in prolonged effects on expression and localization of uterine genes and proteins that participate in regulating uterine functions during early gestation. Furthermore, progesterone concentrations during early gestation affect embryonic growth, interferon-tau production, and uterine function. Therefore, an inadequate uterine environment induced by insufficient steroid concentrations before and after ovulation could cause early embryonic death either by failing to provide an adequate uterine environment for recognition of embryo signaling, adhesion, and implantation or by failing to support appropriate embryonic growth, which could lead to decreased conceptus size and failed maternal recognition of pregnancy.

Dietary supplementation with L-arginine between days 14 and 25 of gestation enhances embryonic development and survival in gilts

Embryonic loss is a major problem in mammals, but there are few effective ways to prevent it. Using a porcine model, we determined effects of dietary L-arginine supplementation between days 14 and 25 of gestation on embryonic growth and survival. Gilts were checked daily for estrus with boars in the morning and bred at onset of the second estrus and 12 h later (the time of breeding = day 0 of gestation). Between days 14 and 25 of gestation, 15 gilts/treatment were housed individually and fed twice daily 1 kg of a corn- and soybean meal-based diet supplemented with 0.0, 0.4, or 0.8 % L-arginine. All diets were made isonitrogenous by addition of L-alanine. On day 25 of gestation, gilts were hysterectomized to obtain conceptuses. Compared with controls, dietary supplementation with 0.4 or 0.8 % L-arginine increased (P ≤ 0.05) arginine concentrations in maternal plasma, total volume of amniotic fluid; total amounts of arginine in allantoic and amniotic fluids; total amounts of fructose and most amino acids in amniotic fluid; placental growth; and the number of viable fetuses per litter by 2. The numbers of total fetuses, fetal weight, corpora lutea, volume of allantoic fluid, maternal circulating levels of progesterone and estrogen, or total amounts of hormones in allantoic fluid did not differ among the three treatment groups. Reproductive performance of gilts did not differ between the 0.4 and 0.8 % L-arginine groups. Thus, dietary supplementation with 0.4 or 0.8 % L-arginine between days 14 and 25 of gestation enhances embryonic/fetal survival in swine.

Arginine, leucine, and glutamine stimulate proliferation of porcine trophectoderm cells through the MTOR-RPS6K-RPS6-EIF4EBP1 signal transduction pathway

During the peri-implantation and early placentation periods in pigs, conceptuses (embryo and its extra-embryonic membranes) undergo dramatic morphological changes and differentiation that require the exchange of nutrients (histotroph) and gasses across the trophectoderm and a true epitheliochorial placenta. Of these nutrients, arginine (Arg), leucine (Leu), and glutamine (Gln) are essential components of histotroph; however, little is known about changes in their total amounts in the uterine lumen of cyclic and pregnant gilts and their effects on cell signaling cascades. Therefore, we determined quantities of Arg, Leu, and Gln in uterine luminal fluids and found that total recoverable amounts of these amino acids increased in pregnant but not cyclic gilts between Days 12 and 15 after onset of estrus. We hypothesized that Arg, Leu, and Gln have differential effects on hypertrophy, hyperplasia, and differentiated functions of trophectoderm cells that are critical to conceptus development. Primary porcine trophectoderm (pTr) cells treated with either Arg, Leu, or Gln had increased abundance of phosphorylated RPS6K, RPS6, and EIF4EBP1 compared to basal levels, and this effect was maintained for up to 120 min. When pTr cells were treated with Arg, Leu, and Gln, low levels of pRPS6K and pEIF4EBP1 were detected in the cytosol, but the abundance of nuclear pRPS6K increased. Immunofluorescence analyses revealed abundant amounts of pRPS6 protein in the cytoplasm of pTr cells treated with Arg, Leu, and Gln. These amino acids also increased proliferation of pTr cells. Furthermore, when Arg, Leu, and Gln were combined with siRNAs for either MTOR, RPTOR, or RICTOR, effects of those amino acids on proliferation of pTr cells were significantly inhibited. Collectively, these results indicate that Arg, Leu, and Gln act coordinately to stimulate proliferation of pTr cells through activation of the MTOR-RPS6K-RPS6-EIF4EBP1 signal transduction pathway.

L-Arginine enhances cell proliferation and reduces apoptosis in human endometrial RL95-2 cells

BACKGROUND

L-arginine is considered to be one of the most versatile amino acids due to the fact that it serves as a precursor for many important molecules in cellular physiology. When supplemented in the diet, L-arginine can increase the number of implantation sites in mice and rats, suggesting an effect at the level of the endometrium. To this end, this study determined the effect that L-arginine has on apoptosis and cell proliferation in human endometrial RL95-2 cells.

RESULTS

L-arginine at physiological (200 micromol/L) and supra-physiological (800 micromol/L) concentrations increased cell proliferation at days 2 and 4 post-treatment with a dose-dependent effect being observed on day 2. Additionally, inhibition of nitric oxide (NO) synthase and arginase, which are responsible for the conversion of L-arginine to NO and polyamines, respectively, reduced the proliferative effect of L-arginine. L-arginine also decreased the proportion of cells with TUNEL positive nuclei and increased the ratio of cells with healthy mitochondria compared to cells with a disrupted mitochondrial membrane potential, indicating that L-arginine prevents mitochondrial mediated apoptosis in endometrial RL95-2 cells. Furthermore, exposure to L-arginine did not affect total BAD protein expression; however, L-arginine increased the abundance of phosphorylated BAD protein.

CONCLUSIONS

In summary, L-arginine added to the culture media at physiological (200 micromol/L) and supraphysiological concentrations (800 micromol/L) enhanced endometrial RL95-2 cell proliferation through mechanisms mediated by NO and polyamine biosynthesis. In addition, L-arginine reduced endometrial RL95-2 mitochondrial mediated apoptosis through increased phosphorylation of BAD protein.