Metabolic fate and function of dietary glutamate in the gut

Effect of monosodium glutamate supplementation in diet on fatty acid profiles, genes expression related to lipid metabolism and egg yolk cholesterol in late phase of production in laying hens

In an experiment with four treatments and five replicates, the effects of adding monosodium glutamate (MSG) to the diet in late phase of egg production was studied on performance, and lipid metabolism in laying hens. Dietary treatments included the control basal diet without MSG and the other treatments adding 0.4%, 0.8% and 1.2% MSG in the control diet respectively. The effect of supplementation of MSG on egg weight, egg production, feed conversion ratio and egg mass was insignificant (p < 0.05). Adding MSG to the diet significantly increased feed intake and blood polyunsaturated fatty acids concentration (p < 0.05). Intake of 0.8% and 1.2% MSG in the diet up regulated the mRNA expression of acetyl-coenzyme A carboxylase, fatty acid synthase and lipoprotein lipase in the abdominal and liver tissues in comparison to the control group. Blood very low-density lipoprotein-cholesterol, triglycerides and cholesterol concentration were increased in treatment fed with a diet containing 0.8% MSG compared to the control group (p < 0.05). The effect of MSG on total egg yolk cholesterol concentration was not significant. In conclusion, the results of the present experiment indicated that adding MSG increased feed intake and blood polyunsaturated fatty acid concentration.

Hematological changes, oxidative stress assessment, and dysregulation of aquaporin-3 channel, prolactin, and oxytocin receptors in kidneys of lactating Wistar rats treated with monosodium glutamate

High consumption of locally produced delicacies could expose nursing mothers to high monosodium glutamate (MSG) levels, frequently used as a necessary condiment in low-income countries. Thus, this study evaluated some novel preliminary changes in renal hormonal receptors, the aquaporin-3 channel, oxidative stress markers, and hematological indices induced by monosodium glutamate in lactating rats. Post-parturition, twenty-four (24) lactating Wistar rats were divided into four (4) groups of six rats each (n = 6). Oral administration of distilled water and MSG started three (3) days postpartum as follows: group 1: distilled water (1 ml/kg BW), group 2: MSG (925 mg/kg BW), group 3: MSG (1850 mg/kg BW), and group 4: MSG (3700 mg/kg BW). At the end of the experiment, which lasted fourteen (14) days, animals were sacrificed and samples of blood and tissues were obtained for biochemical analysis. MSG administration significantly (p < 0.05) increased ROS and MDA, with a significant (p < 0.05) decrease in kidney antioxidants. Serum creatinine, total, conjugated, and unconjugated bilirubin significantly (p < 0.05) increased with MSG administration. The prolactin receptor was significantly reduced (p < 0.05), while the oxytocin receptor and aquaporin-3 channel were significantly (p < 0.05) increased in the MSG-administered groups. There were significant (p < 0.05) changes in the hematological indices of the MSG-administered animals. Thus, the findings of this study suggest that high MSG consumption causes hematological alterations and may alter renal function via increased ROS production and dysregulation of the AQP-3 channel, prolactin, and oxytocin receptors in the kidneys of lactating Wistar rats.

Metabolomics analysis to interpret changes in physiological and metabolic responses to chronic heat stress in Pekin ducks

Heat stress (HS) is a major environmental threat that affects duck production in subtropical and tropical regions, especially in summer. This study aimed to evaluate the physiological and metabolic responses of Pekin ducks to chronic HS conditions via liquid chromatography-mass spectrometry (LC-MS) using a paired-fed (PF) experimental design. On the basis of equivalent feed intake (HS vs. PF), HS significantly reduced growth performance and the percentage of leg and breast muscles, however, markedly increased the percentage of abdominal fat and breast skin fat. Serum metabolomics results revealed that heat-stressed ducks showed enhanced glycolysis and pentose phosphate pathways, as demonstrated by higher glucose 6-phosphate and 6-phogluconic acid levels in the PF vs. HS comparison. HS decreased hepatic mRNA levels of mitochondrial fatty acid β-oxidation-related genes (MCAD and SCAD) compared to the PF group, resulting in acetylcarnitine accumulation in serum. Moreover, HS elevated the concentrations of serum amino acids and mRNA levels of ubiquitination-related genes (MuRF1 and MAFbx) in the skeletal muscle and amino acid transporter-related genes (SLC1A1 and SLC7A1) and gluconeogenesis-related genes (PCK1 and PCase) in the liver compared to the PF group. When compared to the normal control group (NC), HS further decreased growth performance, but it elevated the abdominal fat rate. However, increased mRNA levels of ubiquitination-related genes and serum amino acid accumulation were not observed in the HS group compared to the NC group, implying that reduced feed intake masked the effect of HS on skeletal muscle breakdown and is a form of protection for the organism. These results suggest that chronic HS induces protein degradation in the skeletal muscle to provide amino acids for hepatic gluconeogenesis to provide sufficient energy, as Pekin ducks under HS conditions failed to efficiently oxidise fatty acids and ketones in the mitochondria, leading to poor growth performance and slaughter characteristics.

Untargeted metabolomics analysis reveals spatial metabolic heterogeneity in different intestinal segments of type 1 diabetic mice

Type 1 diabetes (T1D) has been reported to cause systematic metabolic disorders, but metabolic changes in different intestinal segments of T1D remain unclear. In this study, we analyzed metabolic profiles in the jejunum, ileum, cecum and colon of streptozocin-induced T1D and age-matched control (CON) mice by an LC-MS-based metabolomics method. The results show that segment-specific metabolic disorders occurred in the gut of T1D mice. In the jejunum, we found that T1D mainly led to disordered amino acid metabolism and most amino acids were significantly lower relative to CON mice. Moreover, fatty acid metabolism was disrupted mainly in the ileum, cecum and colon of T1D mice, such as arachidonic acid, alpha-linolenic acid and linoleic acid metabolism. Thus, our study reveals spatial metabolic heterogeneity in the gut of T1D mice and provides a metabolic view on diabetes-associated intestinal diseases.

Deciphering survival strategies: Oxidative stress and microbial interplay in Eisenia fetida under tetracycline contamination

Soil contamination resulting from residual antibiotics presents a pressing need to understand the survival mechanisms of soil organisms in polluted environments. This study focused on Eisenia fetida, and tetracycline stress experiments were conducted in a controlled environment using sterile artificial soil. The stress concentration ranged from 0 to 600 mg/kg, and stress cycles lasted either 10 or 30 days. The objective of this study was to assess the effects of oxidative stress and the changes in microbial communities both within and outside the earthworms. A comprehensive mathematical model was developed to elucidate the responses of organisms following exposure to stress utilizing factor analysis, grey relational analysis, and hierarchical entropy weight analysis. Under tetracycline stress, the initial stage (1-3 days) exhibited a coordinated regulation of oxidative stress and microbial communities in the soil with the assistance of CAT and GPX enzymes. The subsequent stage (4-5 days) further emphasized the influence of soil microbial communities. A notable "feedback regulation" of soil microbial communities on oxidative stress was observed during the third stage (6-8 days). Earthworms maintained a metabolic balance in the fourth stage (9-10 days). In the long term, the stress-induced a self-detoxification mechanism within soil microbial communities, which collaborated with GPX to respond to oxidative stress.

Disruptive consequences of monosodium glutamate on male reproductive function: A review

Monosodium glutamate (MSG) is one of the most extensively used flavour enhancers worldwide. Although it is widely regarded as a safe food additive with no recommended daily dosage, its over-consumption has been associated with notably pathophysiological events in various tissues and organs of the body. Previous studies have reported of the neuro- cardio- and hepato- toxic effects of its excessive exposure. Moreover, the food additive instigates metabolic dysfunction. It has been established that MSG damages male reproductive accessory organs like prostate glands and epididymis. In addition, it impairs serum enzymatic activities and serum levels of testosterone, gonadotropin-releasing hormone, luteinizing hormone and cholesterol. Reduced sperm count, sperm motility, sperm morphology, and sperm viability, imbalances in male reproductive hormones, alongside alteration in the histoarchitecture of the testes and other male reproductive tissues have also been connected with excessive exposure to MSG. Literature reports affirm the link between the over-consumption of MSG and reproductive organ weight and male sexual behaviour. This review article addresses the multi-systemic effects of exposure to MSG and the possible mechanism of action of the compound with a focus on the negative implications of the food additive on male reproductive functions and the possible role of natural antioxidants in male reproductive functions. carefully selected keywords were used during the literature search to gather credible and up-to-date information about the subject matter.

Host-microbiota interaction in intestinal stem cell homeostasis

Intestinal stem cells (ISCs) play a pivotal role in gut physiology by governing intestinal epithelium renewal through the precise regulation of proliferation and differentiation. The gut microbiota interacts closely with the epithelium through myriad of actions, including immune and metabolic interactions, which translate into tight connections between microbial activity and ISC function. Given the diverse functions of the gut microbiota in affecting the metabolism of macronutrients and micronutrients, dietary nutrients exert pronounced effects on host-microbiota interactions and, consequently, the ISC fate. Therefore, understanding the intricate host-microbiota interaction in regulating ISC homeostasis is imperative for improving gut health. Here, we review recent advances in understanding host-microbiota immune and metabolic interactions that shape ISC function, such as the role of pattern-recognition receptors and microbial metabolites, including lactate and indole metabolites. Additionally, the diverse regulatory effects of the microbiota on dietary nutrients, including proteins, carbohydrates, vitamins, and minerals (e.g. iron and zinc), are thoroughly explored in relation to their impact on ISCs. Thus, we highlight the multifaceted mechanisms governing host-microbiota interactions in ISC homeostasis. Insights gained from this review provide strategies for the development of dietary or microbiota-based interventions to foster gut health.

Review: A systematic review of the effects of functional amino acids on small intestine barrier function and immunity in piglets

The need to reduce the use of antibiotics and zinc oxide at the pharmacological level, while preserving the performance of postweaning piglets, involves finding adequate nutritional strategies which, coupled with other preventive strategies, act to improve the sustainability of the piglet-rearing system. Amino acids (AAs) are the building blocks of proteins; however, they also have many other functions within the body. AA supplementation, above the suggested nutritional requirement for piglets, has been investigated in the diets of postweaning piglets to limit the detrimental consequences occurring during this stressful period. A systematic review was carried out to summarise the effects of AAs on gut barrier function and immunity, two of the parameters contributing to gut health. An initial manual literature search was completed using an organised search strategy on PubMed, utilising the search term " AND ". These searches yielded 302 articles (published before October 2021); 59 were selected. Based on the method for extracting data (synthesis of evidence), this review showed that L-Arginine, L-Glutamine and L-Glutamate are important functional AAs playing major roles in gut morphology and immune functions. Additional benefits of AA supplementation, refereed to a supplementation above the suggested nutritional requirement for piglets, could also be observed; however, data are needed to provide consistent evidence. Taken together, this review showed that supplementation with AAs during the weaning phase supported a plethora of the physiological functions of piglets. In addition, the data reported confirmed that each amino acid targets different parameters related to gut health, suggesting the existence of potential synergies among them.

Gut microbiota: A new target for traditional Chinese medicine in the treatment of depression

ETHNIC PHARMACOLOGICAL RELEVANCE

The causes of depression are complex. Many factors are involved in its pathogenesis, including the individual's biological and social environment. Although numerous studies have reported that the gut microbiota plays a significant role in depression, drugs that regulate the gut microbiota to treat depression have not yet been comprehensively reviewed. At the same time, more and more attention has been paid to the characteristics of traditional Chinese medicine (TCM) in improving depression by regulating gut microbiota. In ancient times, fecal microbiota transplantation was recorded in TCM for the treatment of severe diseases. There are also records in Chinese ancient books about the use of TCM to adjust gut microbiota to treat diseases, which has opened up a unique research field in TCM. Therefore, this article focuses on the pharmacological effects, targets, and mechanisms of TCM in improving depression by mediating the influence of gut microbiota.

AIM OF THIS REVIEW

To summarize the role the gut microbiota plays in depression, highlight potential regulatory targets, and elucidate the anti-depression mechanisms of TCMs through regulation of the gut microbiota.

METHODS

A systematic review of 256 clinical trials and pharmaceutical studies published until June 2022 was conducted in eight electronic databases (Web of Science, PubMed, SciFinder, Research Gate, ScienceDirect, Google Scholar, Scopus, and China Knowledge Infrastructure), according to the implemented PRISMA criteria, using the search terms "traditional Chinese medicine," "depression," and "gut microbiota."

RESULTS

Numerous studies reported the effects of different gut bacteria on depression and that antidepressants work through the gut microbiota. TCM preparations based on compound Chinese medicine, the Chinese Materia Medica, and major bioactive components exerted antidepressant-like effects by improving levels of neurotransmitters, short-chain fatty acids, brain-derived neurotrophic factor, kynurenine, and cytokines via regulation of the gut microbiota.

CONCLUSION

This review summarized the anti-depression effects of TCM on the gut microbiota, providing evidence that TCMs are safe and effective in the treatment of depression and may provide a new therapeutic approach.

Antcin A, a phytosterol regulates SARS-CoV-2 spike protein-mediated metabolic alteration in THP-1 cells explored by the 1 H-NMR-based metabolomics approach

The mechanism of SARS-CoV-2 spike protein-mediated perturbations of metabolic pathways and modulation of antcin A, a steroid-like compound isolated from Taiwanofungus camphoratus, are not studied. Here, we investigated the metabolic alteration by SARS-CoV-2 spike protein and the regulatory effect of antcin A on SARS-CoV-2 spike protein-induced metabolic changes in the Phorbol 12-myristate 13-acetate (PMA)-induced human monocytes (THP-1) using proton nuclear magnetic resonance (¹ H-NMR) and MetaboAnalyst 5.0 software. The cytotoxic potential of SARS-CoV-2 spike protein, antcin A, and dexamethasone was assessed by MTT assay. The metabolomic perturbations and their relation to human coronaviruses' receptors were evaluated by qPCR. This study indicated that the altered metabolites mediated by SARS-CoV-2 protein, such as methionine, phosphoenolpyruvic acid, canadine, glutamine, ethanolamine, and phenylalanine, were significantly reversed by antcin A. In addition, antcin A significantly inhibited SARS-CoV-2 spike protein-mediated up-regulation of TLR-4 and ACE2 receptors, while GRP78 inhibition was not statistically significant. This is the first study to use ¹ H-NMR to investigate SARS-CoV-2 spike protein-induced metabolomic changes in PMA-induced THP-1 cells. Antcin A significantly reversed metabolomic alters while dexamethasone failed to fix them. Therefore, we believe that antcin A could be a potential candidate for therapeutic agents for viral infections related to a metabolic abnormality.

Heat Shock Protein Response to Stress in Poultry: A Review

Compared to other animal species, production has dramatically increased in the poultry sector. However, in intensive production systems, poultry are subjected to stress conditions that may compromise their well-being. Much like other living organisms, poultry respond to various stressors by synthesising a group of evolutionarily conserved polypeptides named heat shock proteins (HSPs) to maintain homeostasis. These proteins, as chaperones, play a pivotal role in protecting animals against stress by re-establishing normal protein conformation and, thus, cellular homeostasis. In the last few decades, many advances have been made in ascertaining the HSP response to thermal and non-thermal stressors in poultry. The present review focuses on what is currently known about the HSP response to thermal and non-thermal stressors in poultry and discusses the factors that modulate its induction and regulatory mechanisms. The development of practical strategies to alleviate the detrimental effects of environmental stresses on poultry will benefit from detailed studies that describe the mechanisms of stress resilience and enhance our understanding of the nature of heat shock signalling proteins and gene expression.

Aspartate Alleviates Colonic Epithelial Damage by Regulating Intestinal Stem Cell Proliferation and Differentiation via Mitochondrial Dynamics

SCOPE

Proliferation and differentiation of intestinal stem cells (ISCs) are crucial for functional restoration after injury, which can be regulated by nutritional molecules. Aspartate is implicated in maintaining intestinal barrier after injury, but underlying mechanisms remain elusive. Here, this study seeks to investigate if aspartate alleviates colonic epithelial damage by regulating ISC function, and to elucidate its mechanisms.

METHODS AND RESULTS

Eight-week-old male C57BL/6 mice supplement with or without 1% L-aspartate are subjected to drinking water or 2.5% DSS to induce colitis. In this study, aspartate administration alleviates the severity of colitis, as indicated by reduced body weight loss, colon shortening, and inhibited pro-inflammatory cytokine expression in DSS-challenged mice. Additionally, aspartate promotes colonic epithelial cell proliferation and differentiation after DSS-induced damage in mice. Pretreatment with aspartate not only enhances ISC proliferation but also induces ISC differentiation toward enterocytes and goblet cells, which prevent TNF-α-induced colonoid damage. Mechanistically, aspartate ameliorates DSS/TNF-α-induced perturbation of mitochondrial metabolism and maintains mitochondrial dynamics in colonic epithelium and colonoids. Moreover, aspartate-mediated ISC proliferation and differentiation are primarily dependent on mitochondrial fusion rather than fission.

CONCLUSIONS

The findings indicate that aspartate promotes ISC proliferation and differentiation to alleviate colonic epithelial damage by regulation of mitochondrial metabolism and dynamics.

Gestational weight gain and visceral adiposity in adult offspring: Is there a link with the fecal abundance of Acidaminococcus genus?

Intrauterine environment can influence the offspring's body adiposity whose distribution affect the cardiometabolic risk. Underlying mechanisms may involve the gut microbiome. We investigated associations of gestational weight gain with the adult offspring's gut microbiota, body adiposity and related parameters in participants of the Nutritionists' Health Study.

METHODS

This cross-sectional analysis included 114 women who had early life and clinical data, body composition, and biological samples collected. The structure of fecal microbiota was analyzed targeting the V4 region of the 16 S rRNA gene. Beta diversity was calculated by PCoA and PERMANOVA used to test the impact of categorical variables into the diversity. Bacterial clusters were identified based on the Jensen-Shannon divergence matrix and Calinski-Harabasz index. Correlations were tested by Spearman coefficient.

RESULTS

Median age was 28 (IQR 24-31) years and BMI 24.5 (IQR 21.4-28.0) kg/m2. Fifty-eight participants were assigned to a profile driven by Prevotella and 56 to another driven by Blautia. Visceral adipose tissue was correlated to abundance of Acidaminococcus genus considering the entire sample (r = 0.37; p < 0.001) and the profiles (Blautia: r = 0.35, p = 0.009, and Prevotella: r = 0.38, p = 0.006). In Blautia-driven profile, the same genus was also correlated to maternal gestational weight gain (r = 0.38, p = 0.006).

CONCLUSIONS

Association of Acidaminococcus with gestational weight gain could reinforce the relevance with mothers' nutritional status for gut colonization at the beginning of life. Whether Acidaminococcus abundance could be a marker for central distribution of adiposity in young women requires further investigation.

Dietary Moringa oleifera leaf powder improves jejunal permeability and digestive function by modulating the microbiota composition and mucosal immunity in heat stressed rabbits

Heat stress (HS) has detrimental effects on intestinal health by altering digestive and immune responses in animals. Dietary Moringa oleifera leaf powder (MOLP) has been implicated in ameliorating the impact of HS, but its effects in terms of intestinal function improvement under HS remain poorly characterized. Therefore, the current study investigated the impact of HS and MOLP supplementation on tight junction barriers, intestinal microbiota (jejunal digesta), and differentially expressed genes (DEGs) in jejunal mucosa of heat-stressed rabbits by using the next-generation sequencing techniques. A total of 21 male New Zealand White rabbits (32 weeks old mean body weight of 3318 ± 171 g) were divided into three groups (n = 7/group) as control (CON, 25 °C), heat stress (HS, 35 °C for 7 h daily), and HS with MOLP supplementation (HSM, 35 °C for 7 h daily) gavage at 200 mg/kg body weight per day for 4 weeks. The results indicated that MOLP supplementation increased mRNA expression of tight junction proteins and glutathione transferase activity, while the malonaldehyde concentration was decreased in the jejunal mucosa compared to HS group (P < 0.05). Furthermore, MOLP decreased the concentrations of lipopolysaccharide, pro-inflammatory cytokines, and myeloperoxidase compared with HS group (P < 0.05). Intestinal microbiota analysis revealed that at phyla level, the relative abundance of Bacteroidetes was higher in HSM group compared to CON and HS groups. MOLP supplementation also resulted in higher abundance of putatively health-associated genera such as Christensenellaceae R-7 gut group, Ruminococcaceae NK4A214 group, Ruminococcus 2, Lachnospiraceae NK4A136 group, and Lachnospiraceae unclassified along with higher butyrate levels in HSM group as compared to HS group. The analysis of DEGs revealed that MOLP reversed inflammatory response by downregulation of genes, such as TNFRSF13C, LBP, and COX2 in enriched KEGG pathway of NF-kβ pathway. MOLP supplementation also significantly upregulated the expression of genes in protein digestion and absorption pathway, including PRSS2, LOC100349163, CPA1, CPB1, SLC9A3, SLC1A1, and SLC7A9 in HSM group. Three genes of fibrillar collagens, i.e., COL3A1, COL5A3, and COL12A1 in protein digestion were also down-regulated in HSM group. In conclusion, MOLP supplementation could improve jejunal permeability and digestive function, positively modulate microbiota composition and mucosal immunity in heat-stressed rabbits.

Dietary Fatty Acid Intake and the Colonic Gut Microbiota in Humans

A high-fat diet has been associated with systemic diseases in humans and alterations in gut microbiota in animal studies. However, the influence of dietary fatty acid intake on gut microbiota in humans has not been well studied. In this cross-sectional study, we examined the association between intake of total fatty acids (TFAs), saturated fatty acids (SFAs), trans fatty acids (TrFAs), monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs), n3-FAs, and n6-FAs, and the community composition and structure of the adherent colonic gut microbiota. We obtained 97 colonic biopsies from 34 participants with endoscopically normal colons. Microbial DNA was used to sequence the 16S rRNA V4 region. The DADA2 and SILVA database were used for amplicon sequence variant assignment. Dietary data were collected using the Block food frequency questionnaire. The biodiversity and the relative abundance of the bacterial taxa by higher vs. lower fat intake were compared using the Mann−Whitney test followed by multivariable negative binomial regression model. False discovery rate−adjusted p-values (q value) < 0.05 indicated statistical significance. The beta diversity of gut bacteria differed significantly by intake of all types of fatty acids. The relative abundance of Sutterella was significantly higher with higher intake of TFAs, MUFAs, PUFAs, and n6-FAs. The relative abundance of Tyzzerella and Fusobacterium was significantly higher with higher intake of SFAs. Tyzzerella was also higher with higher intake of TrFA. These observations were confirmed by multivariate analyses. Dietary fat intake was associated with bacterial composition and structure. Sutterella, Fusobacterium, and Tyzzerella were associated with fatty acid intake.

Advances in PSMA theranostics

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PSMA is an appealing target for theranostic because it is a transmembrane protein with a known substrate that is overexpessed on prostate cancer cells and internalizes upon ligand binding.

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There are a number of PSMA theranostic ligands in clinical evaluation, clinical trial, or clinically approved.

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PSMA theranostic ligands increase progression-free survival, overall survival, and pain in patients with metastatic castration resistant prostate cancer.

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A major obstacle to PSMA-targeted radioligand therapy is off-target toxicity in salivary glands.

The validation of prostate specific membrane antigen (PSMA) as a molecular target in metastatic castration-resistant prostate cancer has stimulated the development of multiple classes of theranostic ligands that specifically target PSMA. Theranostic ligands are used to image disease or selectively deliver cytotoxic radioactivity to cells expressing PSMA according to the radioisotope conjugated to the ligand. PSMA theranostics is a rapidly advancing field that is now integrating into clinical management of prostate cancer patients. In this review we summarize published research describing the biological role(s) and activity of PSMA, highlight the most clinically advanced PSMA targeting molecules and biomacromolecules, and identify next generation PSMA ligands that aim to further improve treatment efficacy. The goal of this review is to provide a comprehensive assessment of the current state-of-play and a roadmap to achieving further advances in PSMA theranostics.

Dietary L-glutamine affects eggshell quality in the post-peak laying period

In the current study the hypothesis that 1.0% dietary inclusion of glutamine (Gln), a conditionally essential amino acid that influences protein synthesis and shows anti-osteoporotic effect, can influence eggshell quality was tested on laying hens in the post-peak laying period. A 30-week-old Bovans Brown hens were randomly assigned to control group or group supplemented with Gln in the form of alpha-ketoglutarate (10 g/kg) with 12 replicate cages (2 hens/cage) in each group. The experimental period lasted for 30 weeks, from the 31st to the 60th week of age of hens, when eggs were collected and selected eggshell quality indices were determined. While Gln supplementation had no effect on egg geometry and eggshell cracking force, the analysis of eggshell quality showed an increase of the eggshell thickness (P<0.01), porosity (P<0.01), eggshell specific surface (P<0.001) and positive changes in other mechanical parameters (decrease of eggshell stiffness and Young’s modulus, P<0.05 and P<0.01, respectively; increase of work needed to crack the eggshell, P<0.05). Changes in eggshell mineral composition, including an increase of Ca content (P<0.001), were also observed. In conclusion, the current study showed a beneficial effect of Gln on the eggshell thickness, calcification, and some mechanical parameters.

CCK and GLP-1 release in response to proteinogenic amino acids using a small intestine ex vivo model in pigs

The impact of individual amino acids (AA) on gut hormone secretion and appetite regulation in pigs remains largely unknown. The aim of the present study was to determine the effect of the 20 proteinogenic AA on the release of the anorexigenic hormones cholecystokinin (CCK) and glucagon-like peptide 1 (GLP-1) in postweaning pigs. Six 25-d-old male piglets (Domestic Landrace × Large White; body weight = 6.94 ± 0.29 kg) were humanely killed for the collection of intestinal segments from the duodenum, jejunum, and ileum. Tissue samples from the three intestinal segments were used to determine which of the regions were more relevant for the analysis of gut peptides. Only the segments with the highest CCK and GLP-1 secretion and expression levels were evaluated with the 20 individual AA. Tissue segments were cut open, cleaned, and stripped of their muscle layer before identical circular samples were collected and incubated in 24-well plates for 1 h (37 °C, 5% v/v CO₂). The culture broth consisted of a glucose-free KRB buffer containing no added AA (control) or with the addition of 10 mM of 1 of the 20 proteinogenic AA. Following incubation, tissues and supernatant were collected for gene expression and secretion analysis of CCK and GLP-1 levels. CCK secretion and mRNA expression were higher (P < 0.05) in duodenum when compared with proximal jejunum or ileum, whereas GLP-1/proglucagon levels were higher in ileum vs. duodenum (P < 0.05) and jejunum (P < 0.05, for GLP-1 only) in postweaning pigs. Based on these results, the effect of AA on CCK and GLP-1 secretion was studied in the duodenum and ileum, respectively. None of the AA tested stimulated both anorexigenic hormones. Of all the essential AA, Ile, Leu, Met, and Trp significantly (P < 0.05) stimulated GLP-1 from the ileum, while only Phe stimulated CCK from the duodenum. Of the nonessential AA, amide AA (Gln and Asn) caused the release of CCK, while Glu and Arg increased the release of GLP-1 from the ileum. Interpreting the results in the context of the digestion and absorption dynamics, non-bound AA are quickly absorbed and have their effect on gut peptide secretion limited to the proximal small intestine (i.e., duodenum), thus, mainly CCK. In contrast, protein-bound AA would only stimulate CCK release from the duodenum through feedback mechanisms (such as through GLP-1 secreted mainly in the ileum).

Effects of rumen-protected glutamate supplementation during the periparturient period on digestibility, inflammation, metabolic responses, and performance in dairy cows

The objective of this study was to evaluate the effects of feeding rumen-protected glutamate during the periparturient period (d -21 ± 3 to d 21 ± 3 relative to calving) on apparent total-tract digestibility (ATTD), inflammation, metabolic responses, and production performance of dairy cows. Fifty-two multiparous Holstein cows were blocked by parity, body condition score, and expected calving date, and randomly assigned to one of the experimental diets with rumen-protected monosodium glutamate (RP-Glu; intestinally available Glu = 8.8%) or without RP-Glu (control) at d -21 ± 3 relative to expected calving date. The RP-Glu was fed at 4% and 3% of dietary dry matter, before and after calving, respectively. Prepartum diets contained 17.1% and 16.5% crude protein, and 13.1% and 13.3% starch, and postpartum diets contained 18.8% and 18.3% crude protein, and 22.5% and 22.7% starch on a dry matter basis, respectively for RP-Glu and control treatments. A subset of 19 cows was used to measure ATTD. Cows fed the RP-Glu had greater ATTD of dry matter (70.6 vs. 69.1%), crude protein (75.1 vs. 72.6%), and ether extract (66.0 vs 61.2%) on d 5 ± 1 after calving. Cows fed the RP-Glu also had greater dry matter intake (15.7 vs. 13.7 kg/d) on d 1 after calving. Cows fed the RP-Glu had greater plasma concentrations of Glu (4.60 vs. 3.89 µmol/dL) and insulin-like growth factor-1 (44.2 vs. 30.1 mg/mL), lower serum concentrations of free fatty acids (670 vs. 981 μEq/L) and total bilirubin (0.22 vs. 0.34 mg/dL), and lower plasma 3-methylhistidine concentration (1.28 vs. 1.50 μmol/dL) on d 4 after calving. However, these treatment effects observed between d 1 and d 5 ± 1 immediately after calving did not continue until d 21 after calving. Concentrations of serum amyloid A, serum haptoglobin, and plasma lipopolysaccharide binding protein were not affected by the treatment. In addition, no differences were observed for serum β-hydroxybutyrate concentration and milk yield during the postpartum period between the 2 groups, and cows fed the RP-Glu had a decreased lactose yield. These findings suggest that feeding RP-Glu during the periparturient period can increase digestive capacity and feed intake, and decrease mobilization of body fat and protein immediately after calving without increasing milk production.

Effects of supplementing low-protein diets with sodium dichloroacetate and glucose on growth performance, carcass traits, and meat quality of growing-finishing pigs

The objective of this study was to evaluate the effects of supplementing low-protein diets with sodium dichloroacetate (DCA) and glucose on growth performance, carcass traits, and meat quality of growing-finishing pigs. A total of 80 crossbred (Duroc × Landrace × Large White) growing barrows (27 ± 0.4 kg body weight) were allocated randomly to one of the five treatments during three successive 4-wk periods. There were five diets in each phase. Diet 1 was the control diet with normal protein levels (CON) where protein levels in the three phases were 18%, 16.5%, and 15.5%, respectively. The dietary protein levels of Diets 2, 3, 4, and 5 (the low-protein diets, LP) were decreased by 4.5% compared to Diet 1. Additionally, Diets 3 and 4 were supplemented with an extra 120 mg/kg DCA (LP + DCA) or 1.8% glucose (LP + GLUC), respectively. Diet 5 was further supplemented with an extra 120 mg/kg DCA and 1.8% glucose (LP + DCA + GLUC). The LP + DCA diet increased the average daily weight gain of pigs compared to the CON and LP diet in phase 3 and the overall experimental period (P < 0.001). The LP diet reduced the gain:feed ratios of the pigs compared to the CON, LP + DCA, and LP + DCA + GLUC diets in phase 1 and the overall experimental period (P < 0.001). Furthermore, gain:feed ratios in LP + DCA and LP + DCA + GLUC groups did not differ from that of the CON group (P > 0.10). Pigs fed the LP + DCA diet had higher pH values of meat at 24 h post-mortem than the CON group (P < 0.05). The LP + DCA + GLUC diet increased the total protein content in the longissimus dorsi (LD) muscle of pigs, compared to the other dietary treatments (P < 0.05), and increased the Arg and Leu contents in the LD muscle compared to the LP + DCA diet (P < 0.05). Moreover, the LP + DCA diet induced a higher C18:1n9t percentage in the LD muscle of pigs compared to other groups (P < 0.05). In conclusion, an LP diet reduced the feed efficiency in pigs and barely affected meat quality, whereas 120 mg/kg DCA supplementation in an LP diet improved the growth performance of growing-finishing pigs, showed modest effects on carcass traits, and improved the muscle protein content with the addition of glucose.

OUP accepted manuscript

Stable isotope analysis of teeth and bones is regularly applied by archeologists and paleoanthropologists seeking to reconstruct diets, ecologies, and environments of past hominin populations. Moving beyond the now prevalent study of stable isotope ratios from bulk materials, researchers are increasingly turning to stable isotope ratios of individual amino acids to obtain more detailed and robust insights into trophic level and resource use. In the present article, we provide a guide on how to best use amino acid stable isotope ratios to determine hominin dietary behaviors and ecologies, past and present. We highlight existing uncertainties of interpretation and the methodological developments required to ensure good practice. In doing so, we hope to make this promising approach more broadly accessible to researchers at a variety of career stages and from a variety of methodological and academic backgrounds who seek to delve into new depths in the study of dietary composition.

The Effect of L-Glutamine on Basal Albumen and Yolk Indices, and Albumen Amino Acids Composition

Simple Summary

At present, with increased consumers’ focus on eating healthy, it is expected that egg protein content and amino acids profile are among the components of eggs that play critical roles in egg selection. Thus, this research investigated the effect dietary L-glutamine supplementation has on basal albumen and yolk indices as well as albumen protein amino acid profile. The study shows a potential role of L-glutamine supplementation for enhancing nutritional values of eggs by the decrease of albumen lipid content and the change of amino acid profile.

Abstract

The current study tested the hypothesis that 1.0% dietary inclusion of L-glutamine (Gln), an non-essential amino acid that influences protein synthesis, can improve internal egg quality, including amino acids profile. Thirty-week-old Bovans Brown laying hens in their middle laying period were assigned to one of the two experimental groups (12 replicate cages, 2 hens/cage) with Gln in the form of alpha-ketoglutarate (10 g/kg) or without Gln inclusion. The experimental period lasted for 30 wks, from the 31st to the 60th week of age of hens, when eggs were collected and selected egg quality indices were determined. Gln supplementation had no effect on albumen and egg yolk share, albumen and yolk basal indices and composition, including yolk cholesterol content. However, Gln decreased the lipid content of the egg albumen (p < 0.001), and influenced albumen amino acid profile, increasing content of asparagine (p < 0.05), phenylalanine (p < 0.05), proline (p < 0.001), tryptophan (p < 0.01), and tyrosine (p < 0.05). In conclusion, the study shows a potential role of Gln supplementation for enhancing nutritional values of eggs by lower lipid content and higher amino acid profile.

Dietary excess regulates absorption and surface of gut epithelium through intestinal PPARα

Intestinal surface changes in size and function, but what propels these alterations and what are their metabolic consequences is unknown. Here we report that the food amount is a positive determinant of the gut surface area contributing to an increased absorptive function, reversible by reducing daily food. While several upregulated intestinal energetic pathways are dispensable, the intestinal PPARα is instead necessary for the genetic and environment overeating-induced increase of the gut absorptive capacity. In presence of dietary lipids, intestinal PPARα knock-out or its pharmacological antagonism suppress intestinal crypt expansion and shorten villi in mice and in human intestinal biopsies, diminishing the postprandial triglyceride transport and nutrient uptake. Intestinal PPARα ablation limits systemic lipid absorption and restricts lipid droplet expansion and PLIN2 levels, critical for droplet formation. This improves the lipid metabolism, and reduces body adiposity and liver steatosis, suggesting an alternative target for treating obesity.

Effects of supplementation of graded level of glutamic acid to crude protein reduced diets on the performance of growing pigs

A total of 150 growing pigs ([Landrace × Yorkshire] × Duroc) with an initial average body weight (BW) of 24.45 kg were used in a 6-week trial to estimate the optimum lysine to glutamic acid ratio in pigs fed low-protein diets supplemented with increasing level of synthetic glutamic acid (Glu). Pigs were randomly allotted to 5 dietary treatments consisting of either control diet (CON) formulated to have 157 g crude protein (CP) or negative control diets (NC, NC1, NC2 and NC3) with 20 g CP reduction and addition of Glu (1.1, 3.9, 6.8 and 9.6 g/kg feed respectively). Supplementing the increasing level of Glu to low CP diets did not exert any linear or quadratic responses in the growth performance parameters as well as nutrient digestibility. The serum creatinine concentration in pigs receiving CON diet showed trends (p = 0.063) in increment compared with pigs receiving NC diet. However, with the increase in the supplementation of Glu, there were no linear or quadratic responses on serum blood urea nitrogen (BUN) and creatinine concentrations. There was a tendency in the reduction (p = 0.088, p = 0.064) of backfat thickness and lean percentage, respectively, at week 3 and a trend in the reduction (p = 0.092) in lean percentage at week 6 in pigs fed NC diet compared with those fed CON diet. The increase in the supplemental level of Glu tended to show quadratic responses in the backfat thickness and lean percentage at week 3 and 6. In conclusion, the growth performance parameters as well as carcass traits with Lys: Glu ratio 1: 2.71 were very close with the mean values of CON diet indicating that 6.8 g Glu when supplemented to 2% CP reduced diet could achieve the comparable growth performance and carcass trait as that of standard basal diet.

Application of RSM for optimization of glutamic acid production by Corynebacterium glutamicum in bath culture

Glutamate plays an important role in different cellular processes. Its new applications in various industries have led to an increase in the production of it while fermentation is a very important economically method. In this study, the production of glutamate by the wild type of Corynebacterium glutamicum PTCC(Persian Type Culture Collection) 1532 was optimized using RSM. Central Composite Design (CCD) was developed by Design-Expert software version 12.0.3.0 (dx-12, State-Ease Inc.) to evaluate the effect of four important variables in five levels on glutamate production. TLC was employed to evaluate glutamate in medium qualitatively and then quantitative estimation was done by HPLC. Normal probability analysis demonstrated that data has a normal distribution. The results of ANOVA analysis showed that the urea concentration both alone and with temperature is the most effective variable in the fermentation process. Based on the quadratic model obtained in CCD, temperature 30 °C; glucose 9 g.dL-1; biotin 9 μg.L-1 and urea concentration of 0.3 g.dL-1 were found optimum conditions with a predicted glutamate production of 19.84 mg.mL-1 with desirable level 1. Therefore RSM can be an effective method to optimize glutamate production and the findings of this study are a guideline for the other amino acids fermentation by C. glutamicum.

Amino acid requirements for laying hens: a comprehensive review

The main aim of this review is to consolidate the relevant published data examining amino acid requirements of layer hens and to reach a new set of recommendation based on these data. There are inconsistences in lysine, sulphur-containing amino acids, threonine, tryptophan, branched-chain amino acids, and arginine recommendations in data that have surfaced since 1994. This review finds that breed, age, basal diet composition, and assessment method have contributed toward inconsistencies in amino acid recommendations. Presently, the development of reduced-protein diets for layer hens is receiving increasing attention because of the demand for sustainable production. This involves quite radical changes in diet composition with inclusions of nonbound, essential and nonessential amino acids. Increasing inclusions of nonbound amino acids into layer diets modifies protein digestive dynamics, and it may influence amino acid requirements in layer hens. This review considers present amino acid recommendations for layer hens and proposes refinements that may better serve the needs of the layer industry in the future.

Using compositional mixed-effects models to evaluate responses to amino acid supplementation in milk replacers for calves

The consequences of supplementing Lys, Met, and Thr in milk replacers (MR) for calves have been widely studied, but scarce information exists about potential roles of other AA (whether essential or not). The effects on growth performance of supplementation of 4 different AA combinations in a mixed ration (25.4% crude protein and 20.3% fat) based on skim milk powder and whey protein concentrate were evaluated in 76 Holstein male calves (3 ± 1.7 d old). The 4 MR were as follows: CTRL with no AA supplementation; PG, supplying additional 0.3% Pro and 0.1% Gly; FY, supplying additional 0.2% Phe and 0.2% Tyr; and KMT, providing additional 0.62% Lys, 0.22% Met, and 0.61% Thr. All calves were fed the same milk allowance program and were weaned at 56 d of study. Concentrate intake was limited to minimize interference of potential differences in solid feed intake among treatments. Animals were weighed weekly, intakes recorded daily, and blood samples obtained at 2, 5, and 7 wk of study to determine serum urea and plasma AA concentrations. Plasma AA concentrations were explored using compositional data analysis, and their isometric log-ratio transformations were used to analyze their potential influence on ADG and serum urea concentration using a linear mixed-effects model. We detected no differences in calf performance and feed intake. Plasma relative concentration of the AA supplemented in the KMT and PG treatments increased in their respective treatments, and, in PG calves, a slight increase in the proportion of plasma Gly, Glu, and branched-chain AA was also observed. The proportions of plasma branched-chain AA, His, and Gln increased, and those of Thr, Arg, Lys, and Glu decreased with calves' age. A specific log-contrast balance formed by Arg, Thr, and Lys was found to be the main driver for lowering serum urea concentrations and increasing calf growth. The use of compositional mixed-effects models identified a cluster formed by the combination of Arg, Thr, and Lys, as a potential AA to optimize calf growth.

Invited Review: Maintain or Improve Piglet Gut Health around Weanling: The Fundamental Effects of Dietary Amino Acids

Gut health has significant implications for swine nutrient utilization and overall health. The basic gut morphology and its luminal microbiota play determinant roles for maintaining gut health and functions. Amino acids (AA), a group of essential nutrients for pigs, are not only obligatory for maintaining gut mucosal mass and integrity, but also for supporting the growth of luminal microbiota. This review summarized the up-to-date knowledge concerning the effects of dietary AA supplementation on the gut health of weanling piglets. For instance, threonine, arginine, glutamine, methionine and cysteine are beneficial to gut mucosal immunity and barrier function. Glutamine, arginine, threonine, methionine and cysteine can also assist with relieving the post-weaning stress of young piglets by improving gut immunological functions, antioxidant capacity, and/or anti-inflammatory ability. Glutamine, glutamate, glycine and cysteine can assist to reconstruct the gut structure after its damage and reverse its dysfunction. Furthermore, methionine, lysine, threonine, and glutamate play key roles in affecting bacteria growth in the lumen. Overall, the previous studies with different AA showed both similar and different effects on the gut health, but how to take advantages of all these effects for field application is not clear. It is uncertain whether these AA effects are synergetic or antagonistic. The interactions between the effects of non-nutrient feed additives and the fundamental effects of AA warrant further investigation. Considering the global push to minimize the antibiotics and ZnO usage in swine production, a primary effort at present may be made to explore the specific effects of individual AA, and then the concert effects of multiple AA, on the profile and functions of gut microbiota in young pigs.

Low-protein diets supplemented with glutamic acid or aspartic acid ameliorate intestinal damage in weaned piglets challenged with hydrogen peroxide

Glutamic acid (Glu) and aspartic acid (Asp) are acidic amino acids with regulatory roles in nutrition, energy metabolism, and oxidative stress. This study aimed to evaluate the effects of low-protein diets supplemented with Glu and Asp on the intestinal barrier function and energy metabolism in weaned piglets challenged with hydrogen peroxide (H₂O₂). Forty piglets were randomly divided into 5 groups: NC, PC, PGA, PG, and PA (n = 8 for each group). Pigs in the NC and PC groups were fed a low-protein diet, while pigs in the PGA, PG, or PA groups were fed the low-protein diet supplemented with 2.0% Glu +1.0% Asp, 2.0% Glu, or 1.0% Asp, respectively. On day 8 and 11, pigs in the NC group were intraperitoneally injected with saline (1 mL/kg BW), while pigs in the other groups were intraperitoneally administered 10% H₂O₂ (1 mL/kg BW). On day 14, all pigs were sacrificed to collect jejunum and ileum following the blood sample collection in the morning. Notably, low-protein diets supplemented with Glu or Asp ameliorated the intestinal oxidative stress response in H₂O₂-challenged piglets by decreasing intestinal expression of genes (P < 0.05) (e.g., manganese superoxide dismutase [MnSOD], glutathione peroxidase [Gpx]-1, and Gpx-4) encoding oxidative stress-associated proteins, reducing the serum concentration of diamine oxidase (P < 0.05), and inhibiting apoptosis of the intestinal epithelium. Glu and Asp supplementation attenuated the upregulated expression of energy metabolism-associated genes (such as hexokinase and carnitine palmitoyltransferase-1) and the H₂O₂-induced activation of acetyl-coenzyme A carboxylase (ACC) in the jejunum and adenosine monophosphate-activated protein kinase–acetyl-ACC signaling in the ileum. Dietary Glu and Asp also ameliorated intestinal barrier damage as indicated by restored intestinal histology and morphology. In conclusion, low-protein diets supplemented with Glu and Asp protected against oxidative stress-induced intestinal dysfunction in piglets, suggesting that this approach could be used as a nutritional regulatory protectant against oxidative stress.

Pleiotropic effects of alpha-ketoglutarate as a potential anti-ageing agent

An intermediate of tricarboxylic acid cycle alpha-ketoglutarate (AKG) is involved in pleiotropic metabolic and regulatory pathways in the cell, including energy production, biosynthesis of certain amino acids, collagen biosynthesis, epigenetic regulation of gene expression, regulation of redox homeostasis, and detoxification of hazardous substances. Recently, AKG supplement was found to extend lifespan and delay the onset of age-associated decline in experimental models such as nematodes, fruit flies, yeasts, and mice. This review summarizes current knowledge on metabolic and regulatory functions of AKG and its potential anti-ageing effects. Impact on epigenetic regulation of ageing via being an obligate substrate of DNA and histone demethylases, direct antioxidant properties, and function as mimetic of caloric restriction and hormesis-induced agent are among proposed mechanisms of AKG geroprotective action. Due to influence on mitochondrial respiration, AKG can stimulate production of reactive oxygen species (ROS) by mitochondria. According to hormesis hypothesis, moderate stimulation of ROS production could have rather beneficial biological effects, than detrimental ones, because of the induction of defensive mechanisms that improve resistance to stressors and age-related diseases and slow down functional senescence. Discrepancies found in different models and limitations of AKG as a geroprotective drug are discussed.

l-Glutamate drives porcine intestinal epithelial renewal by increasing stem cell activity via upregulation of the EGFR-ERK-mTORC1 pathway

l-Glutamate (Glu) is a nutritionally functional amino acid for pigs. In addition, intestinal stem cells (ISCs) maintain epithelial renewal and homeostasis by dynamically regulating proliferation and differentiation to cope with environmental cues. The rapid renewal of the intestinal epithelium requires a continuous supply of energy sources such as Glu. However, the effects of Glu on ISCs and epithelial renewal are poorly understood. In this study, we found that dietary Glu accelerated intestinal epithelial renewal and gut growth. The epidermal growth factor receptor (EGFR)/extracellular regulated protein kinase (ERK) pathway and mechanistic target of rapamycin complex 1 (mTORC1) signaling were involved in this response in piglets. Subsequent cellular assessment suggested that the EGFR/ERK pathway was upstream of Glu-induced mTORC1 signaling activation. Furthermore, we found that Glu activated the EGFR/ERK pathway and promoted ISC proliferation and differentiation in porcine intestinal organoids. Collectively, our findings suggest that Glu drives intestinal epithelial renewal by increasing ISC activity via the EGFR/ERK/mTORC1 pathway. The present study provides direct evidence that mTORC1 is activated by extracellular Glu through EGFR and that Glu acts as a nutritionally functional amino acid for piglets to maintain intestinal growth and health.

The effect of oral administration of monosodium glutamate on orofacial pain response and the estimated number of trigeminal ganglion sensory neurons of male Wistar rats

Monosodium glutamate (MSG) is a worldwide flavor enhancer. The excessive glutamate concentration in nerve tissue induces the death of nerve cells, known as excitotoxicity. In the orofacial region, the nerve cells’ death affects pain perception such as mechanical hyperalgesia and allodynia. The aim of the present study was to examine the pain response modification and the estimated total number of trigeminal ganglion sensory neurons after sub chronic oral administration of MSG. Twenty eight male Wistar rats, aged 6-8 weeks (100-150 grams) were divided into 4 groups: Control (2 mL NaCl 0.9%); 1 mg/gWB MSG; 2 mg/gWB MSG; 4 mg/gWB MSG groups. Daily oral administration of MSG was given for 30 days. The control group received NaCl per oral for the same period. The pin prick and air puff test were performed on days 1-2, days 41-42 and days 55-56. The number of trigeminal ganglion sensory neurons were estimated by the unbiased stereology method, using the approach of numerical density and organ volume reference. The results showed that the sub chronic oral administration of MSG does not modify either the orofacial pain response or the estimated total number of trigeminal ganglion sensory neurons. .

Alpha-Ketoglutarate: An Effective Feed Supplement in Improving Bone Metabolism and Muscle Quality of Laying Hens: A Preliminary Study

The aim of the experiment was to assess the effect of dietary alpha-ketoglutarate (AKG) supplementation on performance, serum hormonal indices, duodenum and jejunum histomorphometry, meat quality characteristics, bone quality traits and cartilage degradation in laying hens with a mature skeletal system. Forty-eight 30 week-old Bovans Brown laying hens were randomly assigned to a control group or the group fed the basal diet plus 1.0% AKG. The experimental trial lasted 30 weeks. The supplementation of AKG increases blood serum content of leptin, ghrelin, bone alkaline phosphatate and receptor activator of nuclear factor kappa-Β ligand, while osteoprotegerin and osteocalcin decrease. While dietary AKG was given to laying hens negatively influenced villus length, crypt depth, villus/crypt ratio and absorptive surface area in duodenum and jejunum, these changes have no effect on feed intake, weight gain, nor laying performance. In breast muscles, no significant changes in skeletal muscle fatty acid composition were observed, however, a higher shear force and decreased cholesterol content following AKG supplementation were noted, showing the improvement of muscle quality. While dietary AKG supplementation did not affect the general geometric and mechanical properties of the tibia, it increased collagen synthesis and enhanced immature collagen content. In medullary bone, an increase of bone volume fraction, trabecular thickness, fractal dimension and decrease of trabecular space were observed in AKG supplemented group. The trabeculae in bone metaphysis were also significantly thicker after AKG supplementation. AKG promoted fibrillogenesis in articular cartilage, as indicated by increased cartilage oligomeric matrix protein immunoexpression. By improving the structure and maintaining the proper bone turnover rate of highly reactive and metabolically active medullar and trabecular bones AKG showed its anti-osteoporotic action in laying hens.

Dietary Addition of Antioxidant Complex Packs and Functional Amino Acids Can Improve the Digestion, Absorption, and Immunity of Huanjiang Minipigs

To study the effect of functional amino acids and the antioxidant function compound package on Huanjiang minipigs and to lay a foundation for the formulation of green and efficient feed for Huanjiang minipigs, we added functional amino acids and the antioxidant function compound package to piglet feed for 28 days. After feeding, we detected the growth performance, biochemical indexes, inflammatory indexes, and intestinal disaccharidase of piglets. It was found that functional amino acids and the antioxidant compound package had certain effects on the growth performance and biochemical indexes of piglets and could reduce the level of IL-6 and increase the level of LZM and SIgA of piglets, and the levels of lactase and maltase in the intestine also increased significantly. The results showed that the compound package of functional amino acids and antioxidation could improve the growth performance and immunity of piglets and promote the digestion and absorption of nutrients in piglets.

Dispensable Amino Acids, except Glutamine and Proline, Are Ideal Nitrogen Sources for Protein Synthesis in the Presence of Adequate Indispensable Amino Acids in Adult Men

BACKGROUND

Nutritionally, there is a dietary requirement for indispensable amino acids (IAAs) but also a requirement for nitrogen (N) intake for the de novo synthesis of the dispensable amino acids (DAAs). It has been suggested that there might be a dietary requirement for specific DAAs.

OBJECTIVES

Experiment 1 tested whether 9 of the DAAs (Ala, Arg, Asn, Asp, Gln, Glu, Gly, Pro, Ser) are ideal N sources using the indicator amino acid oxidation (IAAO) technique. Experiment 2 examined whether there is a dietary requirement for Glu in adult men.

METHODS

Seven healthy men (aged 20-24 y) participated in 11 or 2 test diet intakes, in experiment 1 and 2, respectively, in a repeated measures design. In experiment 1, a base diet consisting of the IAA provided at the RDA was compared with test intakes with the base diet plus addition of individual DAAs to meet a 50:50 ratio of IAA:DAA on an N basis. In experiment 2, the diets corresponded to the amino acid pattern present in egg protein, in which all Glu and Gln was present as Glu, or removed, with Ser used to make the diets isonitrogenous. On each study day the IAAO protocol with l-[1-13C]phenylalanine was used to measure whole-body protein synthesis.

RESULTS

In experiment 1, repeated measures ANOVA with post hoc multiple comparisons showed that 7 of the 9 DAAs (Ala, Arg, Asn, Asp, Glu, Gly, Ser) decreased IAAO significantly (P < 0.05) compared with base IAA diet, the exceptions being Gln and Pro. In experiment 2, a paired t test did not find significant (P > 0.05) differences in the IAAO in response to removal and replacement of Glu intake.

CONCLUSIONS

The results suggest that in healthy men most DAAs are ideal N sources for protein synthesis, in the presence of adequate IAAs, and that endogenous synthesis of Glu is sufficient.Registered clinicaltrials.gov identifier: NCT02009917.

Dietary glutamate and the brain: In the footprints of a Jekyll and Hyde molecule

Glutamate is a crucial neurotransmitter of the mammalian central nervous system, a molecular component of our diet, and a popular food-additive. However, for decades, concerns have been raised about the issue of glutamate's safety as a food additive; especially, with regards to its ability (or otherwise) to cross the blood-brain barrier, cause excitotoxicity, or lead to neuron death. Results of animal studies following glutamate administration via different routes suggest that an array of effects can be observed. While some of the changes appear deleterious, some are not fully-understood, and the impact of others might even be beneficial. These observations suggest that with regards to the mammalian brain, exogenous glutamate might exert a double-sided effect, and in essence be a two-faced molecule whose effects may be dependent on several factors. This review draws from the research experiences of the authors and other researchers regarding the effects of exogenous glutamate on the brain of rodents. We also highlight the possible implications of such effects on the brain, in health and disease. Finally, we deduce that beyond the culinary effects of exogenous glutamate, there is the possibility of a beneficial role in the understanding and management of brain disorders.

The genetic basis of high-carbohydrate and high-monosodium glutamate diet related to the increase of likelihood of type 2 diabetes mellitus: a review

Diabetes is one of the most common metabolic diseases. Aside from the genetic factor, previous studies stated that other factors such as environment, lifestyle, and paternal-maternal condition play critical roles in diabetes through DNA methylation in specific areas of the genome. One of diabetic cases is caused by insulin resistance and changing the homeostasis of blood glucose control so glucose concentration stood beyond normal rate (hyperglycemia). High fat diet has been frequently studied and linked to triggering diabetes. However, most Asians consume rice (or food with high carbohydrate) and food with monosodium glutamate (MSG). This habit could lead to pathophysiology of type 2 diabetes mellitus (T2D). Previous studies showed that high-carbohydrate or high-MSG diet could change gene expression or modify protein activity in body metabolism. This imbalanced metabolism can lead to pleiotropic effects of diabetes mellitus. In this study, the authors have attempted to relate various changes in genes expression or protein activity to the high-carbohydrate and high-MSG-induced diabetes. The authors have also tried to relate several genes that contribute to pathophysiology of T2D and proposed several ideas of genes as markers and target for curing people with T2D. These are done by investigating altered activities of various genes that cause or are caused by diabetes. These genes are selected based on their roles in pathophysiology of T2D.

Lactobacillus plantarum DR7 Modulated Bowel Movement and Gut Microbiota Associated with Dopamine and Serotonin Pathways in Stressed Adults

We have previously reported that the administration of Lactobacillus plantarum DR7 for 12 weeks reduced stress and anxiety in stressed adults as compared to the placebo group, in association with changes along the brain neurotransmitters pathways of serotonin and dopamine-norepinephrine. We now aim to evaluate the effects of DR7 on gut functions, gut microbiota compositional changes, and determine the correlations between microbiota changes and the pathways of brain neurotransmitters. The administration of DR7 prevented an increase of defecation frequency over 12 weeks as compared to the placebo (p = 0.044), modulating the increase of stress-induced bowel movement. Over 12 weeks, alpha diversity of gut microbiota was higher in DR7 than the placebo group across class (p = 0.005) and order (p = 0.018) levels, while beta diversity differed between groups at class and order levels (p < 0.001). Differences in specific bacterial groups were identified, showing consistency at different taxonomic levels that survived multiplicity correction, along the phyla of Bacteroides and Firmicutes and along the classes of Deltaproteobacteria and Actinobacteria. Bacteroidetes, Bacteroidia, and Bacteroidales which were reduced in abundance in the placebo group showed opposing correlation with gene expression of dopamine beta hydrolase (DBH, dopamine pathway; p < 0.001), while Bacteroidia and Bacteroidales showed correlation with tryptophan hydroxylase-II (TPH2, serotonin pathway; p = 0.001). A correlation was observed between DBH and Firmicutes (p = 0.002), Clostridia (p < 0.001), Clostridiales (p = 0.001), Blautia (p < 0.001), and Romboutsia (p < 0.001), which were increased in abundance in the placebo group. Blautia was also associated with TDO (p = 0.001), whereas Romboutsia had an opposing correlation with TPH2 (p < 0.001). Deltaproteobacteria and Desulfovibrionales which were decreased in abundance in the placebo group showed opposing correlation with DBH (p = 0.001), whereas Bilophila was associated with TPH2 (p = 0.001). Our present data showed that physiological changes induced by L. plantarum DR7 could be associated with changes in specific taxa of the gut microbiota along the serotonin and dopamine pathways.

Dietary glutamine, glutamate, and aspartate supplementation improves hepatic lipid metabolism in post-weaning piglets

A previous study has demonstrated that early weaning significantly suppressed hepatic glucose metabolism in piglets. Glutamate (Glu), aspartate (Asp) and glutamine (Gln) are major metabolic fuels for the small intestine and can alleviate weaning stress, and therefore might improve hepatic energy metabolism. The objective of this study was to investigate the effects of administration of Glu, Asp and Gln on the expression of hepatic genes and proteins involved in lipid metabolism in post-weaning piglets. Thirty-six weaned piglets were assigned to the following treatments: control diet (Control; basal diet + 15.90 g/kg alanine); Asp, Gln and Glu-supplemented diet (Control + AA; basal diet + 1.00 g/kg Asp + 5.00 g/kg Glu + 10.00 g/kg Gln); and the energy-restricted diet supplemented with Asp, Gln and Glu (Energy⁻ + AA; energy deficient diet + 1.00 g/kg Asp + 5.00 g/kg Glu + 10.00 g/kg Gln). Liver samples were obtained on d 5 and 21 post-weaning. Piglets fed Energy⁻ + AA diet had higher liver mRNA abundances of acyl-CoA oxidase 1 (ACOX1), succinate dehydrogenase (SDH), mitochondrial transcription factor A (TFAM) and sirtuin 1 (SIRT1), as well as higher protein expression of serine/threonine protein kinase 11 (LKB1), phosphor-acetyl-CoA carboxylase (P-ACC) and SIRT1 compared with piglets fed control diet (P < 0.05) on d 5 post-weaning. Control + AA diet increased liver malic enzyme 1 (ME1) and SIRT1 mRNA levels, as well as protein expression of LKB1 and P-ACC on d 5 post-weaning (P < 0.05). On d 21 post-weaning, compared to control group, Glu, Gln and Asp supplementation up-regulated the mRNA levels of ACOX1, ME1 and SIRT1 (P < 0.05). These findings indicated that dietary Glu, Gln and Asp supplementation could improve hepatic lipid metabolism to some extent, which may provide nutritional intervention for the insufficient energy intake after weaning in piglets.

Free Amino Acids in Human Milk: A Potential Role for Glutamine and Glutamate in the Protection Against Neonatal Allergies and Infections

Breastfeeding is indicated to support neonatal immune development and to protect against neonatal infections and allergies. Human milk composition is widely studied in relation to these unique abilities, which has led to the identification of various immunomodulating components in human milk, including various bioactive proteins. In addition to proteins, human milk contains free amino acids (FAAs), which have not been well-studied. Of those, the FAAs glutamate and glutamine are by far the most abundant. Levels of these FAAs in human milk sharply increase during the first months of lactation, in contrast to most other FAAs. These unique dynamics are globally consistent, suggesting that their levels in human milk are tightly regulated throughout lactation and, consequently, that they might have specific roles in the developing neonate. Interestingly, free glutamine and glutamate are reported to exhibit immunomodulating capacities, indicating that these FAAs could contribute to neonatal immune development and to the unique protective effects of breastfeeding. This review describes the current understanding of the FAA composition in human milk. Moreover, it provides an overview of the effects of free glutamine and glutamate on immune parameters relevant for allergic sensitization and infections in early life. The data reviewed provide rationale to study the role of free glutamine and glutamate in human milk in the protection against neonatal allergies and infections.

Deciphering the compatibility rules of traditional Chinese medicine prescriptions based on NMR metabolomics: A case study of Xiaoyaosan

ETHNOPHARMACOLOGICAL RELEVANCE

Xiaoyaosan (XYS), a represent and classic TCM prescription, consists of Radix Bupleuri, Radix Angelicae Sinensis, Radix Paeoniae Alba, Rhizoma Atractylodis Macrocephalae, Poria, Herba Menthae, Rhizoma Zingiberis Recens and Radix Glycyrrhizae. XYS can sooth the liver and strengthen the spleen through improving the circulation of qi and nourishing blood according to the TCM theory, therefore exhibiting anti-depression effects.

AIM OF THE STUDY

This study was conducted to investigate the compatibility rule of antidepressant effect of XYS by using both the "Efficacy Compositions" research strategy and fecal metabolomics approach.

MATERIALS AND METHODS

XYS was divided into two efficacy groups, i.e. the Shugan (SG) and the Jianpi (JP) groups, according to the efficacies of both XYS and the eight herbs recorded in the TCM theory and the research strategy of "Efficacy Compositions". A CUMS-induced depression model was constructed, where rats were randomly divided into 5 groups: negative control (NC), CUMS model (MS), XYS, SG, and JP. Multivariate data analysis including Principal Components Analysis (PCA) and Orthogonal Partial Least Squares-Discriminate Analysis (OPLS-DA) was utilized. Efficacy Index (EI) was calculated.

RESULTS

Metabolic profiling by PCA showed that XYS exhibited the strongest effect than the two efficacy groups, locating closest to the control group. OPLS-DA showed 10 metabolites were identified as potential biomarkers for the CUMS-induced depression. 8 potential biomarkers were significantly reversed by XYS while 5 and 4 biomarkers were reversed by SG and JP, respectively. The results of regulatory degrees showed that XYS had the highest EI than SG and JP. Concerning metabolic pathways, XYS regulated all the seven metabolic pathways associated with CUMS-induced depression, while SG and JP groups regulated six and three pathways, respectively.

CONCLUSIONS

The antidepressant effect of XYS was stronger than that of SG and JP. The combined effects of SG and JP brought the integrated antidepressant effect of XYS. This study suggests that a combination of "Efficacy Compositions" strategy and metabolomics approach has great potentials in comprehensively and deeply understanding the scientific connotation of the compatibility rule of TCM prescriptions.

Metabolic studies reveal that ruminal microbes of adult steers do not degrade rumen-protected or unprotected L-citrulline

In vitro and in vivo experiments were conducted to determine the metabolism of rumen-protected or unprotected l-citrulline (Cit) plus l-glutamine (Gln) by ruminal microbes. In the in vitro experiment, whole ruminal fluid (3 mL, containing microorganisms) from steers was incubated at 37 ºC with 5 mM Cit plus 6 mM Gln (in a rumen-protected or unprotected form) for 0, 0.5, 2, or 4 h after which times 50 µL samples were collected for AA and ammonia analyses. In the in vivo experiment, at 0.5 h before and 0, 0.5, 1, 2, 4, and 6 h after cannulated adult steers consumed 0.56 kg dried-distillers' grain mixed with 70 g Cit plus 70 g Gln (in a rumen-protected or unprotected form), samples of ruminal fluid and jugular venous blood were obtained for AA analyses. Results from both in vitro and in vivo experiments demonstrated extensive hydrolysis of rumen-unprotected Gln into glutamate, but little degradation of the rumen-protected Gln or rumen-protected and unprotected Cit by ruminal microbes. Concentrations of Cit and arginine in the plasma of steers consuming rumen-protected or unprotected AA increased at 1 and 2 h after the meal, respectively, when compared with values at 0 h. Collectively, these novel findings indicate that ruminal microbes of adult steers do not degrade extracellular Cit in a rumen-protected or unprotected form. Our results refute the view that all dietary AAs are extensively catabolized by ruminal microorganisms and also have important implications for dietary supplementation with Cit to ruminants to enhance the concentration of arginine in their plasma and their productivity.

Dietary β-hydroxy-β-methylbutyrate improves intestinal function in weaned piglets after lipopolysaccharide challenge

OBJECTIVES

The aim of this study was to explore the effects of β-hydroxy-β-methylbutyrate (HMB) on intestinal function of lipopolysaccharide (LPS)-challenged piglets.

METHODS

Forty weaned piglets were used in a 2 × 2 factorial design. The major factors were challenge (saline or LPS) and diet (basal diet or 0.6% HMB-Ca diet). After 15 d of treatment with LPS or HMB, blood and intestine samples were obtained.

RESULTS

The results showed that in LPS-injected pigs, HMB supplementation significantly increased jejunal villus height and ileal villus height-to-crypt depth ratio and decreased ileal crypt depth (P < 0.05). HMB also improved intestinal function indicated by elevated activities of intestinal mucosal disaccharidase and tricarboxylic acid cycle key enzymes. Furthermore, HMB significantly downregulated mRNA expression of Sirt1 in jejunum and mRNA expression of AMPKα1 and Sirt1 in ileum (P < 0.05), with a concurrent decrease of AMPKα phosphorylation in jejunum and ileum. Microbiota analysis indicated that HMB supplementation significantly increased α-diversity and affected relative abundances of Romboutsia and Sarcina at the genus level, accompanied by increased concentrations of all short-chain fatty acids except propionate in the terminate ileum of LPS-injected piglets.

CONCLUSION

Dietary HMB supplementation could improve intestinal integrity, function, microbiota communities, and short-chain fatty acid concentrations in LPS-challenged piglets, suggesting its potential usage as a feed additive in weaned piglets to alleviate intestinal dysfunction triggered by immune stress.

Effects of adding sodium dichloroacetate to low-protein diets on nitrogen balance and amino acid metabolism in the portal-drained viscera and liver of pigs

Background

Identifying regulatory measures to promote glucose oxidative metabolism while simultaneously reducing amino acid oxidative metabolism is one of the foremost challenges in formulating low-protein (LP) diets designed to reduce the excretion of nitrogen-containing substances known to be potential pollutants. In this study, we investigated the effects of adding sodium dichloroacetate (DCA) to a LP diet on nitrogen balance and amino acid metabolism in the portal-drained viscera (PDV) and liver of pigs.To measure nitrogen balance, 18 barrows (40 ± 1.0 kg) were fed one of three diets (n = 6 per group): 18% crude protein (CP, control), 13.5% CP (LP), and 13.5% CP + 100 mg DCA/kg dry matter (LP-DCA). To measure amino acid metabolism in the PDV and liver, 15 barrows (40 ± 1.0 kg) were randomly assigned to one of the three diets (n = 5 per group). Four essential amino acids (Lys, Met, Thr, and Trp) were added to the LP diets such that these had amino acid levels comparable to those of the control diet.

Results

The LP-DCA diet reduced nitrogen excretion in pigs relative to that of pigs fed the control diet (P < 0.05), without any negative effects on nitrogen retention (P > 0.05). There were no differences between the control and LP-DCA groups with respect to amino acid supply to the liver and extra-hepatic tissues in pigs (P > 0.05). The net release of ammonia into the portal vein and production rate of urea in the liver of pigs fed the LP-DCA diet was reduced relative to that of pigs fed the control and LP diets (P < 0.05).

Conclusion

The results indicated that addition of DCA to a LP diet can efficiently reduce nitrogen excretion in pigs and maximize the supply of amino acids to the liver and extra-hepatic tissues.

d-glutamate and Gut Microbiota in Alzheimer's Disease

Background: An increasing number of studies have shown that the brain–gut–microbiota axis may significantly contribute to Alzheimer’s disease (AD) pathogenesis. Moreover, impaired memory and learning involve the dysfunction neurotransmission of glutamate, the agonist of the N-methyl-d-aspartate receptor and a major excitatory neurotransmitter in the brain. This systematic review aimed to summarize the current cutting-edge research on the gut microbiota and glutamate alterations associated with dementia. Methods: PubMed, the Cochrane Collaboration Central Register of Controlled Clinical Trials, and Cochrane Systematic Reviews were reviewed for all studies on glutamate and gut microbiota in dementia published up until Feb 2020. Results: Several pilot studies have reported alterations of gut microbiota and metabolites in AD patients and other forms of dementia. Gut microbiota including Bacteroides vulgatus and Campylobacter jejuni affect glutamate metabolism and decrease the glutamate metabolite 2-keto-glutaramic acid. Meanwhile, gut bacteria with glutamate racemase including Corynebacterium glutamicum, Brevibacterium lactofermentum, and Brevibacterium avium can convert l-glutamate to d-glutamate. N-methyl-d-aspartate glutamate receptor (NMDAR)-enhancing agents have been found to potentially improve cognition in AD or Parkinson’s disease patients. These findings suggest that d-glutamate (d-form glutamate) metabolized by the gut bacteria may influence the glutamate NMDAR and cognitive function in dementia patients. Conclusions: Gut microbiota and glutamate are potential novel interventions to be developed for dementia. Exploring comprehensive cognitive functions in animal and human trials with glutamate-related NMDAR enhancers are warranted to examine d-glutamate signaling efficacy in gut microbiota in patients with AD and other neurodegenerative dementias.

The Determinants of the Human Milk Metabolome and Its Role in Infant Health

Human milk is needed for optimal growth as it satisfies both the nutritional and biological needs of an infant. The established relationship between breastfeeding and an infant’s health is attributable to the nutritional and non-nutritional, functional components of human milk including metabolites such as the lipids, amino acids, biogenic amines and carbohydrates. These components have diverse roles, including protecting the infant against infections and guiding the development of the infant’s immature immune system. In this review, we provide an in-depth and updated insight into the immune modulatory and anti-infective role of human milk metabolites and their effects on infant health and development. We also review the literature on potential determinants of the human milk metabolome, including maternal infectious diseases such as human immunodeficiency virus and mastitis.

Simvastatin Induces Delayed Apoptosis Through Disruption of Glycolysis and Mitochondrial Impairment in Neuroblastoma Cells

Simvastatin, a commonly used cholesterol-lowering drug, inhibits the mevalonate pathway involved in the synthesis of the mitochondrial electron carrier coenzyme Q10 (CoQ10), as well as other bioenergetics substrates. The purpose of this study was to investigate simvastatin exposure on mitochondrial respiration, metabolic fuel preferences, and glucose utilization. We hypothesized that simvastatin at a noncytotoxic dose will impair energy metabolism in human neuroblastoma cells. SK-N-AS cells were exposed at acute and chronic time points and evaluated in a Seahorse XF analyzer, revealing decreased mitochondrial and glycolytic parameters. Flow cytometry showed a significant induction of apoptosis in simvastatin-treated cells at 48 hours. Finally, multiple techniques were used to show that simvastatin-mediated impairment of bioenergetics is more complex than CoQ10 depletion or hampered glucose uptake. Therefore, the data reported here represent a biphasic hit to mitochondria followed by reduction in glucose and glutamine metabolism in neuroblastoma; adding mechanism to potential pleotropic effects of statins.