Trp Supplementation Research Articles

Effects of Dietary Tryptophan on Growth Performance, Plasma Parameters, and Internal Organs of 1-28-Day-Old Sichuan White Geese.

Although the nutrient requirements of geese during the growing stage are known, the dietary requirement of amino acids during the starting period remains unclear. Optimum nutrient supplementation during the starting period is crucial for improved survival rates, body-weight gain, and marketing weight in geese. Our study focused on the effect of dietary tryptophan (Trp) supplementation on the growth performance, plasma parameters, and internal-organ relative weights in 1-28-day-old Sichuan white geese. A total of 1080 1-day-old geese were divided randomly into six Trp-supplemented (0.145%, 0.190%, 0.235%, 0.280%, 0.325%, and 0.370%) groups. Average daily feed intake (ADFI), average daily gain (ADG), and duodenal relative weight were highest in the 0.190% group, brisket protein level and jejunal relative weight in the 0.235% group, and plasma total protein and albumin levels in the 0.325% group (P < 0.05). Dietary Trp supplementation did not significantly affect the relative weights of the spleen, thymus, liver, bursa of Fabricius, kidneys, and pancreas. Moreover, the 0.145% - 0.235% groups showed significantly decreased liver fat (P < 0.05). Based on the non-linear regression analysis of ADG and ADFI, the dietary Trp levels between 0.183% and 0.190% were estimated to be optimal for 1-28-day-old Sichuan white geese. In conclusion, optimal dietary Trp supplementation in 1-28-day-old Sichuan white geese resulted in increased growth performance (0.180% - 0.190%) along with improved proximal intestinal development and brisket protein deposition (0.235%). Our findings provide basic evidence and guidance for optimal levels of Trp supplementation in geese.

Dietary supplementation with tryptophan increases the plasma concentrations of tryptophan, kynurenine, and melatonin in Yili mares

Context Tryptophan (Trp) is the precursor of melatonin (MT) and the latter plays vital physiological roles in mares. Aims The purpose of this experiment was to investigate the effects of dietary Trp supplementation on the plasma Trp, kynurenine (Kyn), 5-hydroxytryptophan (5-HT), and melatonin (MT) concentrations in female Yili horses. Methods Twenty Yili mares aged 2 years with mean bodyweight (BW) of 263.5 ± 14.77 kg and of similar stature were selected and randomly allocated to the control (CON; basal diet), basal diet plus Trp at 20 mg/kg BW (TRP1), basal diet plus Trp at 40 mg/kg BW (TRP2), or basal diet plus Trp at 60 mg/kg BW (TRP3) group. Key results The plasma total Trp, Kyn, and MT concentrations in all Trp groups steadily increased, reached their peak values, and gradually decreased after Trp supplementation between 0 h and 12 h. However, the plasma 5-HT concentration displayed the opposite trend. Peak plasma total Trp and 5-HT concentrations were attained between 1 h and 3 h, while those of KYN and MT appeared between 4 h and 6 h after Trp supplementation. The plasma total Trp and Kyn concentrations were significantly higher in TRP2 and TRP3 than in CON between 1 h and 12 h (P &lt; 0.05) after Trp supplementation. The plasma 5-HT concentration was significantly (P &lt; 0.05) lower in TRP1 than in CON at 3 h, 4 h, 6 h, 9 h, and 12 h after Trp supplementation. The plasma MT concentrations in TRP1 and TRP2 were significantly (P &lt; 0.05) higher than in CON at 3 h, 4 h, and 12 h, and at 0 h, 1 h, and 12 h after Trp supplementation (P &lt; 0.05). Conclusions Dietary Trp supplementation can increase the plasma total Trp, Kyn, and MT concentrations in Yili mares and the optimal Trp dosage was 20 mg/kg BW. Implication The addition of Trp to a basal diet or feed may increase the plasma total Trp, Kyn, and MT concentrations in female horses.

Tryptophan Supplementation Enhances Intestinal Health by Improving Gut Barrier Function, Alleviating Inflammation, and Modulating Intestinal Microbiome in Lipopolysaccharide-Challenged Piglets.

Tryptophan (Trp) can modify the gut microbiota. However, there is no information about the effect of Trp on intestinal microbiota after lipopolysaccharide (LPS) challenge. This study aimed to investigate the effect of Trp on intestinal barrier function, inflammation, antioxidant status, and microbiota in LPS-challenged piglets. A total of 18 weaned castrated piglets were randomly divided into three treatments with 6 replicate per treatment, namely, (i) non-challenged control (CON); (ii) LPS-challenged control (LPS-CON); and (iii) LPS + 0.2% Trp (LPS-Trp). After feeding with control or 0.2% tryptophan-supplemented diets for 35 days, pigs were intraperitoneally injected with LPS (100 μg/kg body weight) or saline. At 4 h post-challenge, all pigs were slaughtered, and colonic samples were collected. The samples were analyzed for gut microbiota, fatty acids, antioxidant parameters, and the expression of mRNA and protein. The community bar chart showed that Trp supplementation to LPS-challenged pigs increased the relative abundance of Anaerostipes (P < 0.05) and tended to increase the relative abundance of V9D2013_group (P = 0.09), while decreased the relative abundance of Corynebacterium (P < 0.05) and unclassified_c__Bacteroidia (P < 0.01). Gas chromatography showed that Trp increased the concentrations of acetate, propionate, butyrate, and isovalerate in the colonic digesta (P < 0.05). Trp reduced the mRNA level of pro-inflammatory cytokines (P < 0.01), and increased mRNA level of aryl hydrocarbon receptor, cytochrome P450 (CYP) 1A1 and CYP1B1 (P < 0.05). Correlation analysis results showed that acetate, propionate, and butyrate concentrations were positively correlated with mRNA level of occludin and CYP1B1 (P < 0.05), and were negatively correlated with pro-inflammatory cytokines gene expression (P < 0.05). Isovalerate concentration was positively correlated with catalase activity (P < 0.05), and was negatively correlated with pro-inflammatory cytokines gene expression (P < 0.05). Furthermore, Trp enhanced the antioxidant activities (P < 0.01), and increased mRNA and protein expressions of claudin-1, occludin, and zonula occludens-1 (P < 0.01) after LPS challenge. These results suggest that Trp enhanced intestinal health by a modulated intestinal microbiota composition, improved the short chain fatty acids synthesis, reduced inflammation, increased antioxidant capacity, and improved intestinal barrier function.

RNA-seq reveals insights into molecular mechanisms of metabolic restoration via tryptophan supplementation in low birth weight piglet model.

Low birth weight (LBW) is associated with metabolic disorders in early life. While dietary l-tryptophan (Trp) can ameliorate postprandial plasma triglycerides (TG) disposal in LBW piglets, the genetic and biological basis underlying Trp-caused alterations in lipid metabolism is poorly understood. In this study, we collected 24 liver samples from 1-mo-old LBW and normal birth weight (NBW) piglets supplemented with different concentrations of dietary Trp (NBW with 0% Trp, N0; LBW with 0% Trp, L0; LBW with 0.4% Trp, L4; LBW with 0.8% Trp, L8; N = 6 in each group.) and conducted systematic, transcriptome-wide analysis using RNA sequencing (RNA-seq). We identified 39 differentially expressed genes (DEG) between N0 and L0, and genes within “increased dose effect” clusters based on dose-series expression profile analysis, enriched in fatty acid response of gene ontology (GO) biological process (BP). We then identified RNA-binding proteins including SRSF1, DAZAP1, PUM2, PCBP3, IGF2BP2, and IGF2BP3 significantly (P < 0.05) enriched in alternative splicing events (ASE) in comparison with L0 as control. There were significant positive and negative relationships between candidate genes from co-expression networks (including PID1, ANKRD44, RUSC1, and CYP2J34) and postprandial plasma TG concentration. Further, we determined whether these candidate hub genes were also significantly associated with metabolic and cardiovascular traits in humans via human phenome-wide association study (Phe-WAS), and analysis of mammalian orthologs suggests a functional conservation between human and pig. Our work demonstrates that transcriptomic changes during dietary Trp supplementation in LBW piglets. We detected candidate genes and related BP that may play roles on lipid metabolism restoration. These findings will help to better understand the amino acid support in LBW metabolic complications.

Effects of dietary tryptophan supplementation on body temperature, hormone, and cytokine levels in broilers exposed to acute heat stress

The present study was conducted to investigate the effects of tryptophan (Trp) supplementation on rectal temperature, hormone, and cytokine levels in broilers subjected to acute heat stress. A total of 300 18-day-old female Arbor Acres broilers were randomly allocated to five dietary treatment groups with six replicates per treatment group and ten birds per replicate. Broilers were fed a basal diet and in the thermoneutral conditions (TN, 23 ± 1 °C) was considered as the TN group. Broilers were fed a basal diet and exposed to acute heat stress (HS, 34 ± 1 °C) was regarded as the HS group, and other broilers exposed to acute heat stress (34 ± 1°C) were fed a basal diet supplemented with 0.09%, 0.18%, and 0.27% Trp. Results indicated that acute heat stress increased the rectal temperature (P < 0.05), enhanced the concentrations of corticosterone (CORT), dopamine (DA), adrenaline (Adr), adrenocorticotropic hormone (ACTH), and corticotropin-releasing hormone (CRH) in serum (P < 0.05), and elevated the levels of serum tryptophan hydroxylase (TPH)1, tryptophan 2, 3-dioxygenase (TDO), indoleamine 2, 3-dioxygenase (IDO), and kynurenic acid (P < 0.05), compared with the TN group. Meanwhile, acute heat stress increased the levels of serum Trp, hypothalamic Trp, 5-hydroxytryptophan (5-HT), and interleukin-22 (P < 0.05) relative to the TN group. However, compared with the heat stress group, Trp supplementation decreased the rectal temperature of heat-stressed broilers and dietary 0.09% Trp supplementation decreased the levels of serum CRH and TDO (P < 0.05), increased the levels of serum Trp and IL-22 (P < 0.05) in heat-stressed broilers. In addition, dietary supplemented with 0.18% Trp reduced the levels of serum DA, Adr, noradrenaline (NA), CRH, TDO, IDO, kynurenic acid, IL-1β, and hypothalamic 5-HIAA/5-HT (P < 0.05), increased the levels of serum Trp, 5-HT, and IL-22, and upregulated the concentrations of hypothalamic Trp and 5-HT in heat-stressed broilers (P < 0.05). Moreover, dietary 0.27% Trp supplementation decreased the levels of serum DA, CRH, TDO, and hypothalamic 5-HIAA/5-HT (P < 0.05), and upregulated the levels of serum Trp, 5-HT, IL-22, hypothalamic Trp and 5-HT in heat-stressed broilers (P < 0.05). Taken together, dietary 0.18% Trp supplementation may be the optimal level for broilers reared under acute heat stress.

Effects of dietary leucine and tryptophan on serotonin metabolism and growth performance of growing pigs.

An experiment was conducted to test the hypothesis that increased dietary Trp is needed in high-Leu diets for growing pigs to prevent a drop in plasma serotonin and hypothalamic serotonin concentrations and to maintain growth performance of animals. A total of 144 growing pigs (initial weight: 28.2 ± 1.9 kg) were assigned to 9 treatments in a randomized complete block design with 2 blocks, 2 pigs per pen, and 8 replicate pens per treatment. The 9 diets were formulated in a 3 × 3 factorial with 3 levels of dietary Leu (101%, 200%, or 299% standardized ileal digestible [SID] Leu:Lys), and 3 levels of dietary Trp (18%, 23%, or 28% SID Trp:Lys). A basal diet that met requirements for SID Leu and SID Trp was formulated and 8 additional diets were formulated by adding crystalline L-Leu and (or) L-Trp to the basal diet. Individual pig weights were recorded at the beginning of the experiment and at the conclusion of the 21-d experiment. On the last day of the experiment, 1 pig per pen was sacrificed, and blood and hypothalamus samples were collected to measure plasma urea N, plasma serotonin, and hypothalamic serotonin concentrations. Results indicated that increasing dietary Trp increased (P < 0.05) hypothalamic serotonin, whereas increases (P < 0.05) in average daily gain (ADG) and average daily feed intake (ADFI) were observed only in pigs fed diets containing excess Leu. Increasing dietary Leu reduced (P < 0.05) ADG, ADFI, and hypothalamic serotonin. However, the increase in ADG and ADFI caused by dietary Trp was greater if 299% SID Leu:Lys was provided than if 101% SID Leu:Lys was provided (interaction, P < 0.05). Plasma Leu concentration was positively affected by dietary Leu and negatively affected by dietary Trp, but the negative effect of Trp was greater if 299% SID Leu:Lys was provided than if 101% SID Leu:Lys was provided (interaction, P < 0.05). Plasma concentration of Trp was positively affected by increased dietary Trp and increased dietary Leu, but the increase in plasma concentration of Trp was greater if Leu level was at 101% SID Leu:Lys ratio than at 299% SID Leu:Lys ratio (interaction, P < 0.05). In conclusion, increased dietary Leu reduced ADG, ADFI, and hypothalamic serotonin concentration, and influenced metabolism of several indispensable amino acids, but Trp supplementation partly overcame the negative effect of excess Leu. This demonstrates the importance of Trp in regulation of hypothalamic serotonin, and therefore, feed intake of pigs.

Reproductive and immuno-biochemical response of silver barb (Barbonymus gonionotus) fed dietary l-tryptophan

Tryptophan (Trp) influences several physiological functions, including reproduction, stress and immune function in fishes. The present study investigates the effect of dietary Trp supplementation on growth, reproduction, health of Silver barb, Barbonymus gonionotus. A basal diet (control/T1) with varying level of L-Trp at 0.4% (T2), 0.8% (T3) and 1.6% (T4) were fed to experimental fishes (71.04 ​± ​1.62 ​g) for 60 days period. Results indicate higher growth in groups fed 0.4% L-Trp compared to control (p ​< ​0.05). Percent survival was found to be low in all fed groups; however, 0.4% L-Trp (83.33 ​± ​3.33) was not significant as compared to control (93.33 ​± ​3.33). Significant effect (p ​< ​0.05) of dietary L-Trp was evident on the expression level of GnRH-II gene, with 6.26-fold-changes observed at 0.4% level. Reproductive functions (gonado-somatic index, fecundity and egg diameter) were better in groups fed 0.4% L-Trp (p ​< ​0.05). Ovarian histology indicates advanced maturation in fed groups, compared to the control. However, plasma melatonin showed elevated level in 0.8% and 1.6% L-Trp fed groups (p ​< ​0.05). Hemato-biochemical indices as a measure of the health status of the fish indicates elevated total leukocyte and decreased erythrocyte counts in fed groups (p ​< ​0.05). Blood glucose was lower (48.11 ​± ​1.63 ​mg. dl−1), whereas respiratory burst activity (0.60 ​± ​0.02) was higher in 0.4% Trp compared to other groups (p ​< ​0.05). In conclusion, dietary L-Trp supplementation at 0.4% helps to augment growth performance in Silver barb, besides improving reproductive performance.

PSXII-3 Identification of key metabolic mediators during dietary tryptophan supplementation in low-birth-weight pigs by RNA sequencing

Abstract Low birth weight (LBW) is associated with the development of metabolic syndrome, diabetes mellitus and insulin resistance. While tryptophan (Trp), one of essential amino acids supplied by diet, plays an essential role in fetal growth and development, the effects of Trp supplementation on metabolic processes of postnatal LBW individuals remain unclear. The objective of this study was to identify differentially expressed (DE) genes and altered biological processes in liver of LBW and normal birth weight (NBW) piglets supplemented with Trp. RNA was isolated from liver tissues of three weeks old piglets supplemented with Trp (NBW-0% and LBW-0, 0.4, and 0.8%) and was used for RNA sequencing (RNAseq). There were 100, 191 and 39 DE genes in NBW (N0) and LBW tryptophan 0.4%, 0.8% (L4 and L8) when compared to LBW without Trp supplementation (L0). To determine whether Trp supplementation can resume metabolic regulation-related gene expression to N0 level, DE genes from N0 vs. L0 were clustered into 3 groups based on co-expression trends and clusters were enriched for genes associated with lipid catabolic process, circadian regulation of gene expression and fatty acid response. Further, eight hub genes (PID1, PAFAH2, MAP3K15, ANKRD44, CYP2J34, N4BP2L1, RUSC1 and SALL1) identified in co-expression networks based on Pearson correlation coefficient had strong co-expression coefficients (|r| &amp;gt; 0.9) with each other. In particular, PID1 was significantly associated with many neurological, metabolic, environmental and cardiovascular traits based on phenome-wide association analysis (Phe-WAS). In summary, our study provides novel insights into the molecular mechanism underlying LBW metabolic changes with Trp supplementation in porcine liver tissue and highlights that LBW metabolism restoration may be regulated by genes participating in fatty acid response and cardiovascular diseases.

251 Dietary Tryptophan Supplementation Improves Fat and Glucose Metabolism in Low Birthweight Piglets

Abstract Low birthweight (LBW) is associated with complications such as insulin resistance, obesity and metabolic disturbances of glucose and fat metabolism in early life. Dietary tryptophan (Trp) has been shown to reduce liver fat and suppress hyperglycemia in different species. The objective of this study was to assess the effect of dietary Trp on growth and glucose and fat metabolism in LBW pigs. Piglets (7-days old) weighing &amp;lt; 2 kg were considered as LBW while those weighting &amp;gt; 2 kg were considered as normal birthweight (NBW) and randomly allocated to 4 milk-replacer based treatments (n = 7–8): 1) NBW-0% Trp (NBW-T0), 2) LBW-0% Trp (LBW-T0), 3) LBW-0.4% Trp (LBW-T0.4), and 4) LBW-0.8% Trp (LBW-T0.8) for 3 weeks. Growth parameters and body weight were measured biweekly. At week 3, blood and tissue samples were collected in overnight-fasted pigs after a meal test. The mRNA and protein abundance of key glucose and lipid metabolism markers were determined using qPCR and western blot, respectively. Univariate GLM with Dunnett’s post-hoc test (SPSS®) was used to analyze the data. Growth parameters did not change among groups. Plasma triglycerides concentration was lower in LBW-T0.4 and LBW-T0.8 compared to LBW-T0. Blood glucose was lower in LBW-T0.8 than LBW-T0 at 60 min following the meal test. LBW-T0.8 had a lower transcript and protein abundance of liver glucose transporter-2 relative to LBW-T0. Compared to LBW-T0, LBW-T0.8 had a higher mRNA abundance of glucokinase and tended to have a lower transcript of phosphoenolpyruvate carboxykinase in liver. Relative to LBW-T0, LBW-T0.4 tended to have a lower protein abundance of sodium-glucose co-transporter 1 in jejunum. Compared to LBW-T0, LBW-T0.4 and LBW-T0.8 had a lower transcript of liver acetyl-CoA carboxylase and LBW-T0.4 had a higher transcript of liver 3-hydroxyacyl-CoA dehydrogenase. In conclusion, Trp supplementation reduced the lipogenesis and gluconeogenesis, but increased the glycolysis in LBW piglets.

Dietary tryptophan supplementation does not affect growth but increases brain serotonin level and modulates the expression of some liver genes in zebrafish (Danio rerio).

This study aimed at assessing the effects of the dietary tryptophan (Trp) supplementation on growth and feed utilization, brain serotonin content, and expression of selected liver genes (involved in the liver serotonin pathway, protein synthesis degradation, and antioxidant activity) in zebrafish. A growth trial was conducted with zebrafish juveniles fed five experimental isoproteic (40%DM) and isolipidic (8%DM) fishmeal-based diets containing graded levels of Trp: a Trp-non-supplemented diet (diet Trp0, with 0.22% Trp) and four Trp-supplemented diets containing 2-16 times higher Trp content (diets Trp2, Trp4, Trp8, and Trp16 with 0.40, 0.91, 2.02, and 3.34% Trp, respectively). Diets were tested in quadruplicate, with fish being fed twice a day, 6days a week for 6weeks to apparent visual satiation. At the end of the trial, growth performance and feed utilization were assessed, and fish from all experimental groups were sampled for whole-body composition analysis. In addition, fish fed low (Trp0), medium (Trp4), and high (Trp16) Trp diets were also sampled for analysis of brain serotonin content and liver gene expression. Tested tryptophan levels did not influence growth performance nor feed intake. However, values of energy and nitrogen retention as well as body energy content indicate a better feed utilization with diets containing around 0.9% and 2.0% DM Trp. Brain serotonin content increased with increasing dietary tryptophan levels. In addition, regarding liver genes, dietary treatment had a modulatory effect on the expression of Htr1aa and Htr2cl1 genes (encoding for serotonin receptors), TPH1a gene (encoding for tryptophan hydroxylase, the rate-limiting enzyme in the synthesis of serotonin from tryptophan), TOR gene (involved in protein synthesis), and Keap1 gene (involved in antioxidant responses).

Dietary Tryptophan Supplementation Alters Fat and Glucose Metabolism in a Low-Birthweight Piglet Model.

Low birthweight (LBW) is associated with metabolic complications, such as glucose and lipid metabolism disturbances in early life. The objective of this study was to assess: (1) the effect of dietary tryptophan (Trp) on glucose and fat metabolism in an LBW piglet model, and (2) the role peripheral 5-hydroxytryptamine type 3 (5HT3) receptors in regulating the feeding behavior in LBW piglets fed with Trp-supplemented diets. Seven-day-old piglets were assigned to 4 treatments: normal birthweight-0%Trp (NBW-T0), LBW-0%Trp (LBW-T0), LBW-0.4%Trp (LBW-T0.4), and LBW-0.8%Trp (LBW-T0.8) for 3 weeks. Compared to LBW-T0, the blood glucose was decreased in LBW-T0.8 at 60 min following the meal test, and the triglycerides were lower in LBW-T0.4 and LBW-T0.8. Relative to LBW-T0, LBW-T0.8 had a lower transcript and protein abundance of hepatic glucose transporter-2, a higher mRNA abundance of glucokinase, and a lower transcript of phosphoenolpyruvate carboxykinase. LBW-T0.4 tended to have a lower protein abundance of sodium-glucose co-transporter 1 in the jejunum. In comparison with LBW-T0, LBW-T0.4 and LBW-T0.8 had a lower transcript of hepatic acetyl-CoA carboxylase, and LBW-T0.4 had a higher transcript of 3-hydroxyacyl-CoA dehydrogenase. Blocking 5-HT3 receptors with ondansetron reduced the feed intake in all groups, with a transient effect on LBW-T0, but more persistent effect on LBW-T0.8 and NBW-T0. In conclusion, Trp supplementation reduced the hepatic lipogenesis and gluconeogenesis, but increased the glycolysis in LBW piglets. Peripheral serotonin is likely involved in the regulation of feeding behavior, particularly in LBW piglets fed diets supplemented with a higher dose of Trp.

Tryptophan in the diet ameliorates motor deficits in a rotenone-induced rat Parkinson's disease model via activating the aromatic hydrocarbon receptor pathway.

Background and purposeParkinson's disease (PD), a common neurodegenerative disorder with motor and nonmotor symptoms, does not have effective treatments. Dietary tryptophan (Trp) supplementation has potential benefits for the treatment of multiple disorders. However, whether additional Trp in the diet could be beneficial for PD remains to beinvestigated. In the present study, the neuroprotective role of dietary Trp on a rotenone‐induced rat model of PD was determined.MethodsThe rotenone was injected to build the PD model, and then the rats were treated with Trp in the diet. And then, an open field test, western blot analysis, and enzyme linked immunosorbent assay (ELISA) were performed.ResultsWe observed that dietary Trp significantly ameliorated impaired motor function, upregulated tyrosine hydroxylase expression, inhibited the nuclear transport of Nuclear factor‐kappa B (NF‐κB) in substantia nigra (SN), and downregulated the protein levels of IL‐1β, IL‐6, and TNF‐α in serum in rotenone‐treated rats. However, these patterns were reversed in response to treatment with ampicillin, an agent that can clean intestinal Trp metabolism flora. Moreover, after using CH223191, an inhibitor of the aromatic hydrocarbon receptor (AhR) pathway, dietary Trp could not exert neuroprotective roles in the rotenone‐induced rat model of PD.ConclusionThese results suggest that Trp in the diet can protect against rotenone‐induced neurotoxicity to ameliorate motor deficits, which may be mediated through activating AhR pathway.

The Impact of Tryptophan Supplementation on Sleep Quality: A Systematic Review, Meta-Analysis and Meta-Regression

Abstract Objectives Sleep disturbances have been associated with higher risk of developing a range of health conditions such as impaired cognition, type 2 diabetes mellitus and cardiovascular disease. L-tryptophan (Trp) has been documented to aid sleep, but a systematic compilation of its effect on sleep quality is still limited. This study aimed to assess the effect of Trp supplementation on sleep quality via meta-analysis and meta-regression. The effects of Trp dose (&amp;lt;1 g and ≥ 1 g) was also assessed. Methods A database search was done in PubMed, Medline (Ovid), CINAHL and COCHRANE and a total of 18 articles were collected. Sleep outcomes that were observed include total sleep time (TST), sleep latency (SL), wake after sleep onset (WASO) and sleep efficiency (SE). Extracted data from four articles were also analyzed using random-effect meta-analysis and meta-regression. Standardized mean difference (SMD) was used in meta-analysis. To investigate the dose-dependent efficacy of Trp, the post-intervention sleep outcomes from 18 articles were extracted and categorized into two Trp dose groups: &amp;lt;1g and ≥1g. This was then followed by an independent t-test comparison. Results Results from the study suggested that Trp supplementation can shorten WASO [SMD − 1.08 min, 95%CI (−1.89, −0.28); −81.03 min/g, P-value = 0.017]. In addition, the group with ≥ 1g Trp supplementation displayed a shorter WASO than the group with Trp &amp;lt; 1g supplementation (Trp &amp;lt; 1g vs. Trp ≥ 1g: 56.55 mins vs. 29.91 mins; P-value: 0.001). However, Trp supplementation did not affect other sleep components. Conclusions Trp supplementation, especially at ≥ 1g, can aid in improving sleep. Funding Sources National University of Singapore, NUS iHealthtech Microbiome in Health, Disease and Ageing.

L-Tryptophan activates the aryl hydrocarbon receptor and induces cell cycle arrest in porcine trophectoderm cells

During implantation, the proliferation of trophectoderm cells (the outer epithelium of blastocysts) is related to conceptus elongation and placenta formation. Tryptophan (Trp) is a key regulator of embryogenesis and embryonic implantation during pregnancy. We sought to determine whether different concentrations of Trp alters porcine trophectoderm (pTr) cell proliferation. pTr cells were cultured in medium containing 40, 500, or 1000 μM Trp. The cell proliferation rate and the progression of the cells through the cell cycle were determined. To identify differentially expressed genes (DEGs) in the pTr cells, we compared mRNA transcriptomes by RNA-Seq after cell treatment with different concentrations of Trp. Some candidate DEGs were identified by quantitative reverse transcription PCR (qPCR). High L-Trp levels (500 and 1000 μM) inhibited cell proliferation and induced cell cycle arrest. We identified 19 DEGs between the 500 μM L-Trp and 40 μM L-Trp groups and 168 DEGs between the 1000 μM L-Trp and 40 μM L-Trp groups and subsequently used qPCR to validate some genes that were upregulated or downregulated. The functional gene networks in which the DEGs were most enriched included those associated with regulating DNA replication and the cell cycle, and the majority of the DEGs in both of these functional pathways was downregulated. The results showed that the addition of 500 and 1000 μM Trp significantly increased the abundance of proteins in the Aryl Hydrocarbon Receptor (AHR) signaling pathway. Collectively, these results indicate a novel and important role for Trp in mediating the proliferation of porcine placental cells largely via the AHR signaling pathway. Additionally, these findings help to explain the side effects of excessive Trp supplementation on placenta development and embryo growth in mammals.

The impact of tryptophan supplementation on sleep quality: a systematic review, meta-analysis, and meta-regression.

L-tryptophan (Trp) has been documented to aid sleep, but a systematic compilation of its effect on sleep quality is still limited. We assessed the effect of Trp supplementation on sleep quality via meta-analysis and meta-regression. The effects of daily Trp dose (<1 g and ≥1 g) were also assessed. A database search was done in PubMed, Medline (Ovid), Cumulative Index to Nursing and Allied Health Literature (CINAHL), and Cochrane and a total of 18 articles were collected. Extracted data from 4 articles were also analyzed using random-effect meta-analysis and meta-regression. Standardized mean difference (SMD) was used in meta-analysis. Results from the study suggested that Trp supplementation can shorten wake after sleep onset (-81.03 min/g, P = 0.017; SMD, -1.08 min [95%CI, -1.89 to -0.28]). In addition, the group receiving ≥1 g Trp supplementation had a shorter wake after sleep onset than the group with Trp < 1g supplementation (Trp <1 g vs Trp ≥1 g: 56.55 vs 28.91 min; P = 0.001). However, Trp supplementation did not affect other sleep components. Trp supplementation, especially at ≥1 g can help improve sleep quality.

The effects of tryptophan and pyridoxine supplied orally to nursing piglets on weight loss and social behavior after weaning

This study evaluated the effect of oral supplementation with tryptophan (Trp) and pyridoxine (Pyr) on the growth performance and social behavior of suckling piglets before and after weaning. At day 14, six suckling piglets per sow were distributed into three treatments and allotted in a randomized block design, with eight replicates and two piglets per experimental unit. Treatments consisted of a Control - oral supplementation with L-alanine (1.70 g), D-glucose (1.74 g) and distilled water (3.44 mL); Trp - oral supplementation with Trp (3.5 g/d) and distilled water; and Trp + Pyr - oral supplementation with Trp (3.5 g/d) + Pyr (0.0095 g/d) and distilled water. Each treatment was supplied orally five times per day (2.5 mL each treatment), from 14 to 21 days old. Piglets were monitored continuously in the nursing phase for 24 h at 21, 28 and 33 days of age to assess the behavior (standing, lying, eating, socializing, sitting and drinking). Piglets receiving oral Trp + Pyr showed a decreased weight loss on the first day after weaning (P = 0.03). Performance was not affected (P &gt; 0.05) by treatments in each studied period, such as in overall period (21 to 34 days) after weaning. Piglets receiving Trp supplementation visited the feeders more frequently from days 21 to 22 (P &lt; 0.01) and from days 28 to 29 (P &lt; 0.02), as well as in the overall period (P &lt; 0.01). It is concluded that high doses of tryptophan with or without high doses of pyridoxine, supplied orally to nursing piglets, reduced the weight loss on the first day after weaning and increased the frequency of visits to the drinkers on the first day after weaning and also to the feeders, mainly from weaning until 7 days after.

Growth performance responses to increased tryptophan supplementation in growing barrows fed three different very low crude protein corn and soybean meal-based diets fortified with essential amino acids.

Seventy-five individually fed barrows averaging 35 kg were used in a series of three experiments for 6-week growth assays (25 barrows each) to determine the effects of l-tryptophan (Trp) supplementation on growth performance and to establish the lower limits of dietary crude protein (CP) levels. Corn and soybean meal (SBM)-based diets containing 9% (Experiment 1), 10% (Experiment 2), and 11% CP (Experiment 3) fortified with deficient essential amino acids (AAs) except Trp were used as basal diets for each experiment. The experimental diets were supplemented with 0.00%, 0.02%, 0.04%, or 0.06% Trp. A 16% CP corn-SBM-based diet was set as a positive control in each experiment, and feed and water were provided ad libitum. Average daily gain and gain-to-feed ratio improved quadratically (P<0.05) as supplemented Trp increased in the 9% and 10% CP group, although these positive effects were not observed in the 11% CP group. Because the maximum performance parameters in 9%, 10%, and 11% CP groups were not different from that of the 16% CP positive control group, the marginally reduced level of dietary CP without growth performance being affected appears to be around 9% at most. A potential reduction of nitrogen intake was clearly indicated.

PSIV-7 Effect of dietary tryptophan supplementation on growth, energy balance and blood metabolites in milk-fed low birth weight pigs

Abstract Low birth weight (LBW) is associated with reduced postnatal growth efficiency, glucose intolerance and type II diabetes mellitus in adulthood. Using a piglet model of LBW, the objective of this study was to investigate the effect of supplemental Trp on growth, energy balance and blood metabolites in LBW pigs. LBW (&amp;lt; 1.0 Kg) and normal birth weight (NBW; &amp;gt; 1.0 Kg) pigs were selected from twelve sows (parity=2–4, litter size=14–18; three LBW and one NBW piglets/sow) and randomly assigned to 4 milk-replacer based treatments (n=7–8; 7 days old) including: 1) NBW with 0% L-Trp (NBW-T0), 2) LBW with 0% L-Trp (LBW-T0), 3) LBW with 0.4% L-Trp (LBW-T0.4), and 4) LBW with 0.8% L-Trp (LBW-T0.8) for 3 weeks. Diets were provided 4–5 times/day and the voluntary intake was measured for each feeding throughout the study. Growth parameters, heat production and body weight were recorded biweekly. After an overnight fast at week 3, pigs were allowed to consume their respective diets for 1 hour and blood samples were collected at baseline (0), 60 and 120 min after the meal test. The data were analyzed using univariate GLM with Dunnett’s post-hoc test (SPSS®). No significant differences were observed on growth parameters (i.e. body weight, heart girth, wither height and body length), growth performance (i.e. average daily gain, average daily feed intake, gain:feed, gain:protein) and heat production when LBW-T0 was compared with LBW-T0.4 and LBW-T0.8. The plasma triglycerides for pigs fed LBW T0.4 and T0.8 was lower compared to that offered LBW-T0, but total cholesterol did not differ across groups. Pigs in LBW-T0.8 group had lower blood glucose than those fed LBW-T0 at 60 min after the meal challenge. In conclusion, Trp supplementation did not affect the growth and energy balance, but reduced the blood glucose and triglycerides concentration in LBW pigs.

"Dietary supplementation of L-tryptophan" increases muscle development, adipose tissue catabolism and fatty acid transportation in the muscles of Hanwoo steers.

This study investigated the effects of dietary rumen-protected L-tryptophan (TRP) supplementation (43.4 mg of L-tryptophan kg−1 body weigt [BW]) for 65 days in Hanwoo steers on muscle development related to gene expressions and adipose tissue catabolism and fatty acid transportation in longissimus dorsi muscles. Eight Hanwoo steers (initial BW = 424.6 kg [SD 42.3]; 477 days old [SD 4.8]) were randomly allocated to two groups (n = 4) of control and treatment and were supplied with total mixed ration (TMR). The treatment group was fed with 15 g of rumen-protected TRP (0.1% of TMR as-fed basis equal to 43.4 mg of TRP kg−1 BW) once a day at 0800 h as top-dressed to TMR. Blood samples were collected 3 times, at 0, 5, and 10 weeks of the experiment, for assessment of hematological and biochemical parameters. For gene study, the longissimus dorsi muscle samples (12 to 13 ribs, approximately 2 g) were collected from each individual by biopsy at end of the study (10 weeks). Growth performance parameters including final BW, average daily gain, and gain to feed ratio, were not different (p > 0.05) between the two groups. Hematological parameters including granulocyte, lymphocyte, monocyte, platelet, red blood cell, hematocrit, and white blood cell showed no difference (p > 0.05) between the two groups except for hemoglobin (p = 0.025), which was higher in the treatment than in the control group. Serum biochemical parameters including total protein, albumin, globulin, blood urea nitrogen, creatinine phosphokinase, glucose, nonesterified fatty acids, and triglyceride also showed no differences between the two groups (p > 0.05). Gene expression related to muscle development (Myogenic factor 6 [MYF6], myogenine [MyoG]), adipose tissue catabolism (lipoprotein lipase [LPL]), and fatty acid transformation indicator (fatty acid binding protein 4 [FABP4]) were increased in the treatment group compared to the control group (p < 0.05). Collectively, supplementation of TRP (65 days in this study) promotes muscle development and increases the ability of the animals to catabolize and transport fat in muscles due to an increase in expressions of MYF6, MyoG, FABP4, and LPL gene.

Exercise but Not Supplemental Dietary Tryptophan Influences Heart Rate and Respiratory Rate in Sled Dogs.

Tryptophan (Trp), an indispensable amino acid for dogs, is the precursor of serotonin, a neurotransmitter with a variety of effects throughout the body, including the ability to modulate cardiac and pulmonary activity. This study aimed to investigate the effects of a 12-week incremental exercise regimen and supplemental dietary Trp on heart rate (HR) and respiratory rate (RR) in client-owned sled dogs. Sixteen Siberian huskies were randomly allocated to either treatment or control diet groups. Both groups were fed a control diet (Trp to large neutral amino acid ratio of 0.047:1); however, treatment dogs received a Trp supplement to achieve a Trp to large neutral amino acid ratio of 0.075:1. Every three weeks, external telemetry equipment was used to non-invasively measure and record HR and RR at a resting, working, and post-exercise state in a controlled exercise challenge. A mixed model was used to test differences between diet, activity parameter, and week. Dietary Trp supplementation had no effect on HR or RR. Independent of diet, resting, working, post-exercise HR, and time to recover post-exercise HR decreased from week −1 to week 11 (p < 0.05). Resting HR had the greatest reduction from week −1 to week 11 (21%, p < 0.05). Working RR did not change with exercise (p > 0.10), but rRR and postRR decreased from week −1 to week 11 (p < 0.05). These data suggest that the exercise regimen the dogs were subjected to may have positively impacted the dogs’ capacity to sustain aerobic exercise, whereas Trp supplementation had no effect on HR or RR.