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

The potential mechanism of MicroRNA involvement in the regulation of muscle development in weaned piglets by tryptophan and its metabolites

BACKGROUND

Muscle development is a key factor influencing the growth performance of piglets. Optimizing this developmental process is crucial for enhancing breeding efficiency and economic profitability. Tryptophan (Trp) is considered one of the key limiting amino acids for weaned piglets, plays an essential role in regulating feed intake, growth, and muscle development. However, the regulatory mechanisms by which Trp and its derivatives influence muscle development in weaned piglets remain unclear.

METHODS

The aim of this study was to investigate the regulatory pathways and potential mechanisms of Trp and its metabolites on muscle development in weaned piglets. In this study, 10 healthy castrated male piglets, 28 days old and weaned, were selected and randomly assigned to a control group (CON, 0.14% Trp) and a high tryptophan group (HT, 0.35% Trp), with 5 in each group. After a 7-day pre-feeding period, the formal feeding began, and after 28 days, the pigs were slaughtered and the longissimus dorsi muscles was collected for transcriptome sequencing.

RESULTS

The results indicated that different dietary Trp levels led to the identification of sixteen differentially expressed microRNAs (DE miRNAs) in the longissimus dorsi muscle of the weaned piglets. Target gene functional enrichment analysis showed that these DE miRNAs are involved in muscle cell proliferation, differentiation, protein deposition, and muscle development through multiple biological pathways. Furthermore, we constructed a protein-protein interaction (PPI) network for the target genes, with the enriched core gene cluster functions associated with cellular proliferation, signaling pathways, hormone release, and muscle development. Finally, qRT-PCR validated the reliability and accuracy of the RNA-seq results, revealing a correlation coefficient of 0.97 between the two methods.

CONCLUSIONS

This study uncovers the potential mechanisms by which miRNAs participate in the regulation of muscle development in weaned piglets mediated by Trp and its metabolites, providing a theoretical basis and practical guidance for optimizing piglet management and health improvement.

Tryptophan-induced effects on the behavior and physiology of aging in tryptophan hydroxylase-2 heterozygous mice C57BL/6N

Background and Aim

Tryptophan (Trp), a precursor of serotonin, plays a critical role in cognitive and emotional processes. Its metabolism through serotonin and kynurenine pathways impacts neuropsychiatric functions and lipid metabolism. This study investigates Trp's effects on the behavioral, physiological, and molecular parameters of aging female wild-type (WT) and heterozygous tryptophan hydroxylase-2 (HET) mice.

Materials and Methods

A 68-day experiment was conducted on 13-month-old WT and HET mice. Groups received either distilled water or Trp supplementation (400 mg/kg/day). Behavioral tests (Open Field, Elevated Zero Maze, Forced Swim, and Extrapolation Escape Task) assessed locomotion, anxiety, and cognition. Physiological assessments included body composition through NMR relaxometry, lipid histology, serotonin content in the brain (ELISA), and serotonergic gene expression (RT-PCR). Blood biochemistry and organ weights were also analyzed.

Results

Trp supplementation reduced growth rates and adipose tissue while increasing muscle mass in both genotypes, more markedly in HET mice. Behavioral tests revealed a decrease in anxiety and enhanced cognitive performance in HET+Trp mice but an increase in immobility. Trp increased brain serotonin content in HET mice and altered serotonergic gene expression. Histological studies showed hepatoprotective effects in HET+Trp mice, reducing liver lipid infiltration compared to WT+Trp mice.

Conclusion

Trp exhibited genotype-specific effects, with HET mice showing anabolic, hepatoprotective, and neuropsychiatric changes. These findings highlight Trp's potential in neuro-nutrition for conditions like depression and cognitive decline. Further studies are needed to explore Trp's metabolic pathways and their implications for personalized dietary interventions.

Supplemental effects of rumen-protected L-tryptophan at various levels on starch digestion, melatonin and gastrointestinal hormones in Holstein steers

The effects of different level of rumen-protected L-tryptophan (RPL-T) supplementation on starch digestion, melatonin (MEL) and gastrointestinal (GI) hormones secretion in Holstein steers were evaluated. Four Holstein steers (201 ± 24 kg) were employed in a 4×4 Latin square design. The dietary treatments were the control (basal diet) and RPL-T groups of basal diet + 191.1 mg/kg body weight (BW), basal diet + 95.6 mg/kg BW, and basal diet + 19.1 mg/kg BW groups. Blood samples were collected to measure blood hormones on day 0, 1, 3, and 5 of the experiment to study serum MEL and GI tract and duodenal starch degradability. The design was 4 × 4 Latin square and the data were analyzed using the ANOVA procedure by SPSS. The D-glucose content in the RPL-T treatment groups was significantly reduced (p < 0.05) compared to the control group. The serum cholecystokinin (CCK) levels were increased in the RPL-T treatment group compared to the control group. However, there was no significant difference between all RPL-T treatment groups. The results of serum MEL were also similar to CCK results. The serum secretin levels were not significantly different (p > 0.05) between all groups. The apparent starch disappearance rates in GI track were lower (p < 0.05) in treatment groups compared with the control, and there was no significant difference between all RPL-T treatment groups. Digestion was increased (p < 0.05) in all treatment groups compared to the control. Overall, there were significant differences in starch digestibility, CCK, and MEL compared to the control group, but there were no significant differences in concentration of RPL-T. Therefore, considering the economic purpose, 19.1mg/kg BW is recommended as an appropriate level of addition to increase the productivity of beef cattle.

Circular RNAs Mediate the Effects of Dietary Tryptophan on the Transformation of Muscle Fiber Types in Weaned Piglets

The nutritional composition of the diet significantly impacts the overall growth and development of weaned piglets. The current study aimed to explore the effects and underlying mechanisms of dietary tryptophan consumption on muscle fiber type transformation during the weaning period. Thirty weaned piglets with an average body weight of 6.12 ± 0.16 kg were randomly divided into control (CON, 0.14% Trp diet) and high Trp (HT, 0.35% Trp) groups and maintained on the respective diet for 28 days. The HT group of weaned piglets exhibited highly significant improvements in growth performance and an increased proportion of fast muscle fibers. Transcriptome sequencing revealed the potential contribution of differentially expressed circular RNAs toward the transformation of myofiber types in piglets and toward the regulation of expression of related genes by targeting the microRNAs, miR-34c and miR-182, to further regulate myofiber transformation. In addition, 145 DE circRNAs were identified as potentially protein-encoding, with the encoded proteins associated with a myofiber type transformation. In conclusion, the current study greatly advances and refines our current understanding of the regulatory networks associated with piglet muscle development and myofiber type transformation and also contributes to the optimization of piglet diet formulation.

Effects of Rumen-Protected L-Tryptophan Supplementation on Productivity, Physiological Indicators, Blood Profiles, and Heat Shock Protein Gene Expression in Lactating Holstein Cows under Heat Stress Conditions

In this study, we examined the effects of rumen-protected L-tryptophan supplementation on the productivity and physiological metabolic indicators in lactating Holstein cows under heat stress conditions. The study involved eight early lactating Holstein cows (days in milk = 40 ± 9 days; milk yield 30 ± 1.5 kg/day; parity 1.09 ± 0.05, p < 0.05), four cows per experiment, with environmentally controlled chambers. In each experiment, two distinct heat stress conditions were created: a low-temperature and low-humidity (LTLH) condition at 25 °C with 35-50% humidity and a high-temperature and high-humidity (HTHH) condition at 31 °C with 80-95% humidity. During the adaptation phase, the cows were subjected to LTLH and HTHH conditions for 3 days. This was followed by a 4-day heat stress phase and then by a 7-day phase of heat stress, which were complemented by supplementation with rumen-protected L-tryptophan (ACT). The findings revealed that supplementation with ACT increased dry matter intake as well as milk yield and protein and decreased water intake, heart rate, and rectal temperature in the HTHH group (p < 0.05). For plateletcrit (PCT, p = 0.0600), the eosinophil percentage (EOS, p = 0.0880) showed a tendency to be lower, while the monocyte (MONO) and large unstained cells (LUC) amounts were increased in both groups (p < 0.05). Albumin and glucose levels were lower in the HTHH group (p < 0.05). The gene expressions of heat shock proteins 70 and 90 in the peripheral blood mononuclear cells were higher in the ACT group (HTHH, p < 0.05). These results suggest that ACT supplementation improved productivity, physiological indicators, blood characteristics, and gene expression in the peripheral blood mononuclear cells of early lactating Holstein cows under heat-stress conditions. In particular, ACT supplementation objectively relieved stress in these animals, suggesting that L-tryptophan has potential as a viable solution for combating heat-stress-induced effects on the cattle in dairy farming.

Exploring and Identifying Candidate Genes and Genomic Regions Related to Economically Important Traits in Hanwoo Cattle

The purpose of the current review was to explore and summarize different studies concerning the detection and characterization of candidate genes and genomic regions associated with economically important traits in Hanwoo beef cattle. Hanwoo cattle, the indigenous premium beef cattle of Korea, were introduced for their marbled fat, tenderness, characteristic flavor, and juiciness. To date, there has been a strong emphasis on the genetic improvement of meat quality and yields, such as backfat thickness (BFT), marbling score (MS), carcass weight (CW), eye muscle area (EMA), and yearling weight (YW), as major selection criteria in Hanwoo breeding programs. Hence, an understanding of the genetics controlling these traits along with precise knowledge of the biological mechanisms underlying the traits would increase the ability of the industry to improve cattle to better meet consumer demands. With the development of high-throughput genotyping, genomewide association studies (GWAS) have allowed the detection of chromosomal regions and candidate genes linked to phenotypes of interest. This is an effective and useful tool for accelerating the efficiency of animal breeding and selection. The GWAS results obtained from the literature review showed that most positional genes associated with carcass and growth traits in Hanwoo are located on chromosomes 6 and 14, among which LCORL, NCAPG, PPARGC1A, ABCG2, FAM110B, FABP4, DGAT1, PLAG1, and TOX are well known. In conclusion, this review study attempted to provide comprehensive information on the identified candidate genes associated with the studied traits and genes enriched in the functional terms and pathways that could serve as a valuable resource for future research in Hanwoo breeding programs.

Dietary supplementation with L-glutamine enhances immunity and reduces heat stress in Hanwoo steers under heat stress conditions

This study investigated the effects of L-glutamine (Gln) supplementation on growth performance, physiological traits, heat shock proteins (HSPs), and gene expression related to muscle and adipose tissue development in Hanwoo steers under heat stress (HS) conditions. Eight Hanwoo steers (initial body weight [BW] 570.7 ± 43.6 kg, months of age 22.3 ± 0.88) were randomly separated into two groups, control and treatment, and supplied with the concentration (1.5% of BW kg/day/head) and rice straw (1.5 kg/day/head). The treatment group were fed the Gln supplementation (0.5% of concentration, as-fed basis) once a day at 08:00 h. Blood samples for the assessment of haematological and biochemical parameters and the separation of peripheral blood mononuclear cells (PBMCs) were collected four times, at 0, 3, 6, and 10 weeks of the experiment. Feed intake was measured daily. BW to analyze growth performance and hair follicle collection to analyze the expression of HSPs were executed four times at 0, 3, 6, and 10 weeks. To analyze gene expression, longissimus dorsi muscle samples were collected by biopsy at the end of the study. As a result, growing performance, including final BW, average daily gain, and gain-to-feed ratio, were not different between the two groups. Leukocytes including lymphocytes and granulocytes, tended to increase in the Gln supplementation group (p = 0.058). There were also no differences in biochemical parameters shown between the two groups, except total protein and albumin, both of which were lower in the Gln supplementation group (p < 0.05). Gene expressions related to muscle and adipose tissue development were not different between the two groups. As temperature-humidity index (THI) increased, HSP70 and HSP90 expression in the hair follicle showed a high correlation. HSP90 in the hair follicle was decreased in the treatment group compared with the control group at 10 weeks (p < 0.05). Collectively, dietary Gln supplementation (0.5% of concentration, as-fed basis) may not be influential enough to affect growth performance and gene expression related to muscle and adipose tissue development in steers. However, Gln supplementation increased the number of immune cells and decreased HSP90 in the hair follicle implying HS reduction in the corresponding group.

Dietary supplementation of acetate-conjugated tryptophan alters feed intake, milk yield and composition, blood profile, physiological variables, and heat shock protein gene expression in heat-stressed dairy cows

The purpose of this study was to investigate the effects of dietary supplementation of rumen-protected tryptophan (RPT) at four levels on milk yield, milk composition, blood profile, physiological variables, and heat shock protein gene expression in dairy cows under conditions of moderate-severe heat stress (MSHS, THI = 80~89). Sixteen early-lactating dairy cows (body weight = 719 ± 66.4 kg, days in milk = 74.3 ± 7.1, milk yield = 33.55 ± 3.74 kg, means ± SEM) were randomly assigned in a factorial arrangement to one of the four treatments: control group (n = 4, no RPT supplementation), 15 g/d RPT (n = 4), 30 g/d RPT (n = 4), or 60 g/d RPT group per cow (n = 4) supplemented to the TMR. A higher dry matter intake (DMI) and milk yield were found in the 30 g RPT group compared with the other groups, and the 3.5% fat-corrected milk yield, energy-corrected milk yield, milk fat, protein, β-casein, mono-unsaturated fatty acid, and poly-unsaturated fatty acid contents, and serum glucose content were observed in the 30 g RPT group (p < 0.05). The milk lactose concentration was significantly higher in the 30 g RPT group compared with the control and 60 g RPT groups (p < 0.05). The plasma cortisol level was lower, while the serotonin and melatonin concentrations were higher in the 30 g group compared with the other groups (p < 0.05). Heat shock protein (HSP) 70 expression was downregulated in the control and 15 g RPT groups, whereas the expression of HSP90 and HSPB1 remained unchanged among the groups. In particular, the 30 g RPT group was considered to have an improved DMI, milk yield, and lactose concentration, as well as anti-heat stress effects due to the simulation of serotonin and melatonin during MSHS.

Supplementing with L-Tryptophan Increases Medium Protein and Alters Expression of Genes and Proteins Involved in Milk Protein Synthesis and Energy Metabolism in Bovine Mammary Cells

The objective of this study was to investigate the effects of supplementing with L-tryptophan (L-Trp) on milk protein synthesis using an immortalized bovine mammary epithelial (MAC-T) cell line. Cells were treated with 0, 0.3, 0.6, 0.9, 1.2, and 1.5 mM of supplemental L-Trp, and the most efficient time for protein synthesis was determined by measuring cell, medium, and total protein at 0, 24, 48, 72, and 96 h. Time and dose tests showed that the 48 h incubation time and a 0.9 mM dose of L-Trp were the optimal values. The mechanism of milk protein synthesis was elucidated through proteomic analysis to identify the metabolic pathway involved. When L-Trp was supplemented, extracellular protein (medium protein) reached its peak at 48 h, whereas intracellular cell protein reached its peak at 96 h with all L-Trp doses. β-casein mRNA gene expression and genes related to milk protein synthesis, such as mammalian target of rapamycin (mTOR) and ribosomal protein 6 (RPS6) genes, were also stimulated (p < 0.05). Overall, there were 51 upregulated and 59 downregulated proteins, many of which are involved in protein synthesis. The results of protein pathway analysis showed that L-Trp stimulated glycolysis, the pentose phosphate pathway, and ATP synthesis, which are pathways involved in energy metabolism. Together, these results demonstrate that L-Trp supplementation, particularly at 0.9 mM, is an effective stimulus in β-casein synthesis by stimulating genes, proteins, and pathways related to protein and energy metabolism.