Sex differences in cachexia and branched-chain amino acid metabolism following chemotherapy in mice.

Chemotherapy is a major contributor to cachexia, but studies often investigate male animals. Here, we investigated whether sex modifies the effects of chemotherapy on cachexia and BCAA metabolism. Ten-week-old CD2F1 male and female mice were treated with the chemotherapy drug cocktail folfiri (50 mg/kg 5-fluorouracil, 90 mg/kg leucovorin, and 24 mg/kg CPT11) (drug) or vehicle twice a week for 6 weeks. Insulin tolerance tests were conducted and BCAA levels and metabolism were measured in plasma and tissues. Drug treatment reduced body and skeletal muscle weights and anabolic signaling in both sexes, with females showing worsened outcomes (p < 0.05 for all). Drug treatment increased plasma BCAA only in males, but BCAA concentrations in the skeletal muscle of both sexes were decreased; this decrease was more profound in males (p = 0.0097). In addition, muscle expression of the BCAA transporter LAT1 was reduced; this reduction was more severe in females (p = 0.0264). In both sexes, the (inhibitory) phosphorylation of BCKD-E1αser293 was increased along with decreased BCKD activity. In the liver, drug treatment increased BCAA concentrations and LAT1 expression, but BCKD activity was suppressed in both sexes (p < 0.05 for all). Our results demonstrate that altered BCAA metabolism may contribute to chemotherapy-induced cachexia in a sex-dependent manner.

Taohe Chengqi decoction alleviated metabolic-associated fatty liver disease by boosting branched chain amino acids catabolism in the skeletal muscles of type 2 diabetes mellitus.

OBJECTIVE: Metabolic-associated fatty liver disease (MAFLD) is the most prevalent liver disease, whereas type 2 diabetes mellitus (T2DM) is considered an independent risk factor for MAFLD incidence. Taohe Chengqi decoction (THCQ) is clinically prescribed for T2DM treatment; however, the hepatoprotective effect of THCQ against MAFLD is still unknown. This study intended to elucidate the therapeutic effect of THCQ on T2DM-associated MAFLD and to investigate the underlying mechanisms. METHODS: THCQ lyophilized powder was prepared and analyzed by UHPLC-MS/MS. A stable T2DM mouse model was established by high-fat diet (HFD) feeding combined with streptozotocin (STZ) injection. The T2DM mice were administered THCQ (2.5 g/kg or 5 g/kg) to explore the pharmacological effects of THCQ on T2DM-associated MAFLD. Liver tissue transcriptome was analyzed and the participatory roles of PPARα/γ pathways were verified both in vivo and in vitro. Serum metabolome analysis was used to explore the metabolome changes and skeletal muscle branched chain amino acid (BCAA) catabolic enzymes were further detected. Moreover, an AAV carrying BCKDHA shRNA was intramuscularly injected to verify the impact of THCQ on skeletal muscle BCAA catabolism and the potential therapeutic outcome on hepatic steatosis. RESULTS: THCQ improved hepatic steatosis in MAFLD. RNA-sequencing analysis showed dysregulation in the hepatic PPARγ-related fatty acid synthesis, while PPARα-dependent fatty acid oxidation was elevated following THCQ treatment. Interestingly, in vitro analyses of these findings showed that THCQ had minor effects on fatty acid oxidation and/or synthesis. The metabolomic study revealed that THCQ accelerated BCAA catabolism in the skeletal muscles, in which knockdown of the BCAA catabolic enzyme BCKDHA diminished the THCQ therapeutic effect on hepatic steatosis. CONCLUSION: This study highlighted the potential therapeutic effect of THCQ on hepatic steatosis in MALFD. THCQ upregulated fatty acid oxidation and reduced its synthesis via restoration of PPARα/γ pathways in HFD/STZ-induced T2DM mice, which is mediated through augmenting BCKDH activity and accelerating BCAA catabolism in the skeletal muscles. Overall, this study provided in-depth clues for "skeletal muscles-liver communication" in the therapeutic effect of THCQ against hepatic steatosis. These findings suggested THCQ might be a potential candidate against T2DM-associated MAFLD.

Reduced Branched-Chain Amino Acid Intake Improved High-Fat Diet-Induced Nonalcoholic Fatty Pancreas Disease in Mice.

OBJECTIVE: To explore the effects of branched-chain amino acids (BCAAs) on nonalcoholic fatty pancreas disease (NAFPD) and its possible mechanism in high-fat diet (HFD) induced mice. MATERIALS AND METHODS: Pancreatic morphology and lipid infiltration was assessed by hematoxylin-eosin staining and immunohistochemistry, and lipid levels in the pancreas were determined using colorimetric enzymatic method. Relevant mechanism was investigated using western blotting and biochemical test. RESULTS: In HFD-fed mice, dietary BCAAs restriction could attenuate body weight increase, improve glucose metabolism, and reduce excessive lipid accumulation in the pancreas. Furthermore, expression of AMPKα and downstream uncoupling protein 1 were upregulated, while genes related to mammalian target of rapamycin complex 1 (mTORC1) signal pathway and lipid de novo synthesis were suppressed in HFD-BCAA restriction group compared with HFD and HFD-high BCAAs fed mice. In addition, BCAA restriction upregulated expression of BCAAs related metabolic enzymes including PPM1K and BCKDHA, and decreased the levels of BCAAs and branched chain keto acid in the pancreas. However, there was no difference in levels of lipid content in the pancreas and gene expression of AMPKα and mTORC1 between HFD and HFD-high BCAAs groups. CONCLUSIONS: Branched-chain amino acid restriction ameliorated HFD-induced NAFPD in mice by activation of AMPKα pathway and suppression of mTORC1 pathway.

Walking exercise through smartphone application plus branched-chain amino acid supplementation benefits skeletal muscle mass and strength in liver cirrhosis: A prospective control trial.

INTRODUCTION AND OBJECTIVES: Whether a combination of exercise and branched-chain amino acid (BCAA) supplementation was more beneficial than those given alone in sarcopenia related to liver cirrhosis (LC) is unknown. Widely used smartphone applications provide continuous and easily expandable management of chronic liver disease (CLD). This study is to investigate the effects of unsupervised walking exercise using WeChat combined with BCAA supplementation on skeletal muscle mass and strength in LC. MATERIALS AND METHODS: The 127 LC patients of Child-Pugh A/B were assigned to group A (BCAA supplements, n=42), group B (walking exercise, n=43) and group C (walking exercise plus BCAA supplements, n=42). Laboratory data, average daily steps, serum BCAA, skeletal muscle mass index (SMI) and grip strength were analyzed pre- and 3 months after interventions. RESULTS: Of the 124 patients who completed interventions, albumin and daily steps were significantly increased in all groups (p=0.0001). Post-intervention BCAA were significantly elevated in group A (A vs B, p=0.001) and C (C vs B, p=0.012;). While post-intervention daily steps in group B (B vs A, p=0.0001) and C (C vs A, p=0.0001) were higher. Grip strength (C vs A, p=0.020; C vs B, p=0.036) and SMI (C vs A, p=0.035; C vs B, p=0.012) were increased in group C. Prevalence of sarcopenia was significantly decreased in group C (p=0.015). CONCLUSIONS: A combination of unsupervised walking exercise using smartphone applications and BCAA supplementation might be an effective and safe treatment for cirrhosis patients with Child-Pugh A/B to improve skeletal muscle mass and strength or to prevent progress of sarcopenia.

The nitrate transporter-sensor MtNPF6.8 regulates the branched chain amino acid/pantothenate metabolic pathway in barrel medic (Medicago truncatula Gaertn.) root tip.

Nitrogen is the most limiting nutrient for plants, and it is preferentially absorbed in the form of nitrate by roots, which adapt to nitrate fluctuations by remodelling their architecture. Although core mechanisms of the response to nitrate availability are relatively well-known, signalling events controlling root growth and architecture have not all been identified, in particular in Legumes. However, the developmental effect of nitrate in Legumes is critical since external nitrate not only regulates root architecture but also N2-fixing nodule development. We have previously shown that in barrel medic (Medicago truncatula), the nitrate transporter MtNPF6.8 is required for nitrate sensitivity in root tip. However, uncertainty remains as to whether nitrogen metabolism itself is involved in the MtNPF6.8-mediated response. Here, we examine the metabolic effects of MtNPF6.8-dependent nitrate signalling using metabolomics and proteomics in WT and mtnpf6.8 root tips in presence or absence of nitrate. We found a reorchestration of metabolism due to the mutation, in favour of the branched chain amino acids/pantothenate metabolic pathway, and lipid catabolism via glyoxylate. That is, the mtnpf6.8 mutation was likely associated with a specific rerouting of acetyl-CoA production (glyoxylic cycle) and utilisation (pantothenate and branched chain amino acid synthesis). In agreement with our previous findings, class III peroxidases were confirmed as the main protein class responsive to nitrate, although in an MtNPF6.8-independent fashion. Our data rather suggest the involvement of other pathways within mtnpf6.8 root tips, such as Ca2+ signalling or cell wall methylation.

Effect of a single intravenous injection of branched chain amino acids on body temperature of cats undergoing general anesthesia.

OBJECTIVE: To evaluate the effect of a single intravenous injection of branched chain amino acids (BCAAs) on body temperature in cats undergoing general anesthesia. STUDY DESIGN: Prospective, blinded, randomized, crossover, experimental study. ANIMALS: A total of 10 healthy adult cats (five female and five male). METHODS: Cats were anesthetized three times with three different treatments in a random order: 3 mL kg-1 lactated Ringer's solution (LRS), 100 mg kg-1 BCAAs (B100) or 200 mg kg-1 BCAAs (B200) solution immediately before induction of anesthesia. After induction, rectal temperature was measured every 5 minutes. Blood samples were collected for the measurement of blood glucose (BG) just before induction, at the end of the 90 minute period of anesthesia, and 24 hours after anesthesia induction. The differences between baseline and each subsequent rectal temperature, and BG measurements were analyzed. Areas under the curve (AUCs) for temperature differences were calculated for each animal for the anesthetic period (AUCT0-90). Parametric or nonparametric data were analyzed by one-way repeated measures anova or Friedman test. A value of p < 0.05 was considered significant. RESULTS: There were no significant differences in AUCT0-90 between groups: 41.6 ± 7.7 for LRS, 43.4 ± 6.9 for B100 and 42.9 ± 7.5 for B200 (p = 0.368). No significant differences were observed in BG between groups at 90 minutes and 24 hours after anesthesia induction (p = 0.283 and p = 0.089, respectively). The incidence of hypoglycemia [BG ≤ 3.17 mmol L-1 (57 mg dL-1)] after anesthesia tended to be higher in both B100 (4/10 cats) and B200 groups (3/10 cats) than in LRS group (1/10 cats). CONCLUSIONS AND CLINICAL RELEVANCE: A single, preanesthetic intravenous injection of BCAAs did not attenuate heat loss during anesthesia. More cats were hypoglycemic in the BCAA groups than in the LRS group.

Physiological 4-phenylbutyrate promotes mitochondrial biogenesis and metabolism in C2C12 myotubes.

Type 2 diabetes is characterized by elevated circulating blood metabolites such as glucose, insulin, and branched chain amino acids (BCAA), which often coincide with reduced mitochondrial function. 4-Phenylbutyrate (PBA), an ammonia scavenger, has been shown to activate BCAA metabolism, resolve endoplasmic reticulum (ER) stress, and rescue BCAA-mediated insulin resistance. To determine the effect of PBA on the altered metabolic phenotype featured in type 2 diabetes, the present study investigated the effect of PBA on various metabolic parameters including mitochondrial metabolism and mitochondrial biogenesis. C2C12 myotubes were treated with PBA at 0.5 mM (representing physiologically attainable blood concentrations) or 10 mM (representing physiologically unattainable/proof-of-concept levels) for up to 24 h. Mitochondrial and glycolytic metabolism were assessed via oxygen consumption and extracellular acidification rate, respectively. Mitochondrial content, lipid content, and ER stress were measured by fluorescent staining. Metabolic gene expression was measured by qRT-PCR. Both doses of PBA increased expression of indicators of mitochondrial biogenesis, though only PBA at 0.5 mM increased mitochondrial function and content while 10 mM PBA reduced mitochondrial function and content. PBA at 0.5 mM also rescued reduced mitochondrial function during insulin resistance, though PBA also caused a reduced insulin stimulated pAkt expression during insulin resistance. PBA treatment also increased extracellular BCAA accumulation during insulin resistance despite unchanged pBCKDH expression. Taken together, PBA may increase mitochondrial biogenesis, content, and function in a dose-dependent fashion which may have implications for prevention or treatment of metabolic disease such as insulin resistance.

Disrupted cardiac fibroblast BCAA catabolism contributes to diabetic cardiomyopathy via a periostin/NAP1L2/SIRT3 axis.

BACKGROUND: Periostin is an extracellular matrix protein that plays a critical role in cell fate determination and tissue remodeling, but the underlying role and mechanism of periostin in diabetic cardiomyopathy (DCM) are far from clear. Thus, we aimed to clarify the mechanistic participation of periostin in DCM. METHODS: The expression of periostin was examined in DCM patients, diabetic mice and high glucose (HG)-exposed cardiac fibroblasts (CF). Gain- and loss-of-function experiments assessed the potential role of periostin in DCM pathogenesis. RNA sequencing was used to investigate the underlying mechanisms of periostin in DCM. RESULTS: A mouse cytokine antibody array showed that the protein expression of periostin was most significantly upregulated in diabetic mouse heart, and this increase was also observed in patients with DCM or HG-incubated CF. Periostin-deficient mice were protected from diabetes-induced cardiac dysfunction and myocardial damage, while overexpression of periostin held the opposite effects. Hyperglycemia stimulated the expression of periostin in a TGF-ß/Smad-dependent manner. RNA sequencing results showed that periostin upregulated the expression of nucleosome assembly protein 1-like 2 (NAP1L2) which recruited SIRT3 to deacetylate H3K27ac on the promoters of the branched-chain amino acid (BCAA) catabolism-related enzymes BCAT2 and PP2Cm, resulting in BCAA catabolism impairment. Additionally, CF-derived periostin induced hypertrophy, oxidative injury and inflammation in primary cardiomyocytes. Finally, we identified that glucosyringic acid (GA) specifically targeted and inhibited periostin to ameliorate DCM. CONCLUSION: Overall, manipulating periostin expression may function as a promising strategy in the treatment of DCM.

Salmonella mutant strains resistant to herbicides - Acetohydroxyacid synthase inhibitors and their use at the Ames test.

Cytotoxicity of some pesticides is a disadvantage for the Salmonella/microsome assay with regard to the equivalence assessment of pesticide technical grade active ingredients to the original products and detection of low-level impurities. The technical grade active ingredients (TGAIs) of pesticides from certain chemical classes were found to be toxic for Salmonella typhimurium strains. Among the highly cytotoxic compounds were sulfonylureas, which include 20 active ingredients. In addition, this class includes active pharmaceutical ingredients used for the manufacture of antidiabetics drugs. A traditional selection methodology was applied using the cultivation of S. typhimurium TA100 in the presence of high concentrations of thifensulfuronmethyl (TFSM) to obtain a resistant test strain insusceptible to sulfonylurea toxic effect. Two strains resistant not only to sulfonylureas (SFU) but also triazolepyrimidines were received. The first mutant strain (deposited as S. typhimurium VKPM B-14099 in the Russian National Collection of Industrial Microorganisms) demonstrated the TA100 phenotypic characteristics: hisG46, rfa, ΔuvrB-bio, pKM101. The second strain (deposited as S. typhimurium VKPM B-14359) showed the TA1535 phenotypic characteristics and probably lost the R-factor due to the selection using the poor Gm-media with TFSM. Positive controls caused pronounced mutagenic effects (±S9) in both strains, consequently the mutants did not lose the ability to respond to induction of the reverse gene mutations. The maximum non-cytotoxic concentrations of SFUs and triazole-pyrimidines for the Ames test strains did not exceed 0.05-0.125 mg/plate, while no evidence of cytotoxicity was observed for the mutants up to 5.0 mg/plate. Electron microscopy of the ultrathin sections of Salmonella cells grown with and without TFSM showed an obvious difference in the structure of the cell wall and cytoplasm in mutant and parental cultures. The concurrent resistance both to SFU and triazolepyrimidines was assumed to be mediated by the same mechanism of action of the pesticides from these classes - inhibition of acetohydroxyacid synthase. To confirm this hypothesis, the tests in the presence of branched-chain amino acids were carried out. The enrichment of agar with isoleucine prevented the toxic effects of SFU and triazolepyrimidines for all Ames test strains used in the study, while strong cytotoxicity was observed in the presence of valine and leucine. Considering the tolerance of strains both to SFU and triazolpyrimidines and the results with branched-chain amino acids, the modification of target acetohydroxyacid synthase was supposed the key to the acquired resistance. The new strains resistant to sulfonylureas and triazole-pyrimidines expands the possibilities to reveal mutagenic impurities that may occur in TGAIs in small amounts.

The effects of arginine and branched-chain amino acid supplementation to reduced-protein diet on intestinal health, cecal short-chain fatty acid profiles, and immune response in broiler chickens challenged with Eimeria spp.

We investigated the effects of supplementing arginine (Arg) and branched-chain amino acids (BCAA) in broilers fed reduced-protein diets and challenged with Eimeria spp. All birds were fed the same starter diet meeting Cobb 500 nutrient specifications from d 1 to 9. Four grower diets: positive control (PC) with 20.0% crude protein (CP); reduced-protein negative control (NC) with 17.5% CP; or NC supplemented with Arg or BCAA at 50% above recommendations (ARG or BCAA) were fed to the birds from d 9 to 28. Birds were allocated in a 2 × 4 factorial arrangement (4 diets, each with or without challenge), with 8 replicates per treatment. On d 14, the challenge groups were orally gavaged with mixed Eimeria spp. Intestinal permeability was higher (P < 0.05) in NC than PC, whereas the permeability of ARG and BCAA groups did not differ significantly from PC. On d 28, a significant interaction (P < 0.01) was observed in CD8+: CD4+ ratios in cecal tonsils (CT), Eimeria challenge increased the ratios in all groups except for the ARG group. On d 21, a significant interaction was found for CD4+CD25+ percentages in CT (P < 0.01) that Eimeria challenge increased the percentages only in PC and NC groups. On d 21 and 28, significant interactions (P < 0.01) were found for macrophage nitric oxide (NO) production. In nonchallenged birds, NO was higher in the ARG group than other groups, but in challenged birds, NO was higher in both ARG and BCAA groups. On d 21, a significant interaction was found for bile anticoccidial IgA concentrations (P < 0.05) that Eimeria challenge increased IgA only in NC and ARG groups. The results suggest that a reduced-protein diet exacerbates the impact of the Eimeria challenge on intestinal integrity, but this could be mitigated by Arg and BCAA supplementations. Arginine and BCAA supplementations in reduced-protein diets could be beneficial for broilers against Eimeria infection by enhancing the immune responses. The beneficial effects of Arg supplementation tended to be more pronounced compared to BCAA supplementation.

Involvement of a flavoprotein, acetohydroxyacid synthase, in growth and riboflavin production in riboflavin-overproducing Ashbya gossypii mutant.

BACKGROUND: Previously, we isolated a riboflavin-overproducing Ashbya gossypii mutant (MT strain) and discovered some mutations in genes encoding flavoproteins. Here, we analyzed the riboflavin production in the MT strain, in view of flavoproteins, which are localized in the mitochondria. RESULTS: In the MT strain, mitochondrial membrane potential was decreased compared with that in the wild type (WT) strain, resulting in increased reactive oxygen species. Additionally, diphenyleneiodonium (DPI), a universal flavoprotein inhibitor, inhibited riboflavin production in the WT and MT strains at 50 µM, indicating that some flavoproteins may be involved in riboflavin production. The specific activities of NADH and succinate dehydrogenases were significantly reduced in the MT strain, but those of glutathione reductase and acetohydroxyacid synthase were increased by 4.9- and 25-fold, respectively. By contrast, the expression of AgGLR1 gene encoding glutathione reductase was increased by 32-fold in the MT strain. However, that of AgILV2 gene encoding the catalytic subunit of acetohydroxyacid synthase was increased by only 2.1-fold. These results suggest that in the MT strain, acetohydroxyacid synthase, which catalyzes the first reaction of branched-chain amino acid biosynthesis, is vital for riboflavin production. The addition of valine, which is a feedback inhibitor of acetohydroxyacid synthase, to a minimal medium inhibited the growth of the MT strain and its riboflavin production. In addition, the addition of branched-chain amino acids enhanced the growth and riboflavin production in the MT strain. CONCLUSION: The significance of branched-chain amino acids for riboflavin production in A. gossypii is reported and this study opens a novel approach for the effective production of riboflavin in A. gossypii.

Elevated branched-chain amino acid promotes atherosclerosis progression by enhancing mitochondrial-to-nuclear H2O2-disulfide HMGB1 in macrophages.

As the essential amino acids, branched-chain amino acid (BCAA) from diets is indispensable for health. BCAA supplementation is often recommended for patients with consumptive diseases or healthy people who exercise regularly. Latest studies and ours reported that elevated BCAA level was positively correlated with metabolic syndrome, diabetes, thrombosis and heart failure. However, the adverse effect of BCAA in atherosclerosis (AS) and its underlying mechanism remain unknown. Here, we found elevated plasma BCAA level was an independent risk factor for CHD patients by a human cohort study. By employing the HCD-fed ApoE-/- mice of AS model, ingestion of BCAA significantly increased plaque volume, instability and inflammation in AS. Elevated BCAA due to high dietary BCAA intake or BCAA catabolic defects promoted AS progression. Furthermore, BCAA catabolic defects were found in the monocytes of patients with CHD and abdominal macrophages in AS mice. Improvement of BCAA catabolism in macrophages alleviated AS burden in mice. The protein screening assay revealed HMGB1 as a potential molecular target of BCAA in activating proinflammatory macrophages. Excessive BCAA induced the formation and secretion of disulfide HMGB1 as well as subsequent inflammatory cascade of macrophages in a mitochondrial-nuclear H2O2 dependent manner. Scavenging nuclear H2O2 by overexpression of nucleus-targeting catalase (nCAT) effectively inhibited BCAA-induced inflammation in macrophages. All of the results above illustrate that elevated BCAA promotes AS progression by inducing redox-regulated HMGB1 translocation and further proinflammatory macrophage activation. Our findings provide novel insights into the role of animo acids as the daily dietary nutrients in AS development, and also suggest that restricting excessive dietary BCAA consuming and promoting BCAA catabolism may serve as promising strategies to alleviate and prevent AS and its subsequent CHD.

Comparison of an Antioxidant Source and Antioxidant Plus BCAA on Athletic Performance and Post Exercise Recovery of Horses.

Antioxidant supplementation decreases postexercise oxidative stress but could also decrease muscle protein synthesis. This study compared the effects of three diets: low antioxidant (control, CON), high antioxidant (AO), and branched-chain amino acid high antioxidant (BCAO) supplementation on postexercise protein synthesis and oxidative stress. We hypothesized that supplementing antioxidants with branched-chain amino acids(BCAA) would reduce oxidative stress without hindering muscle protein synthesis. Eighteen mixed-breed polo horses (11 mares and 7 geldings, with age range between 5 and 18 years, were on CON diet for 30 days (from day -45 until day 0) and then were assigned to one of the treatments after the first lactate threshold test (day 0, LT). LT were also conducted on days 15 and 30 of supplemenation. Oxidative stress was assessed by measuring blood glutathione peroxidase, superoxide dismutase, and malondialdehyde concentrations before 2 and 4 hours after each LT. Muscle biopsies were taken before and 4 hours after each LT and analyzed for gene expression of protein synthesis by RTqPCR. Data were analyzed by ANOVA and compared by least-square means. A reduction in oxidative stress occurred over time (P < .05), from day 0 to day 30. An up-regulation in the abundance of muscle protein mRNA transcripts was found for CD36, CPT1, PDK4, MYF5, and MYOG (P < .05) after all lactate threshold tests, without a treatment effect. A treatment-by-exercise effect was observed for MYOD1 (P = .0041). Transcript abundance was upregulated in AO samples post exercise compared to other treatments. MYF6 exhibited a time-by-treatment effect (P = .045), where abundance increased more in AO samples from day 0 to day 15 and 30 compared to other treatments. Transcript abundance for metabolic and myogenic genes was upregulated in post exercise muscle samples with no advantage from supplementation of antioxidants with branched-chain amino acids compared to antioxidants alone.

Branched chain amino acids-friend or foe in the control of energy substrate turnover and insulin sensitivity?

Branched chain amino acids (BCAA) and their derivatives are bioactive molecules with pleiotropic functions in the human body. Elevated fasting blood BCAA concentrations are considered as a metabolic hallmark of obesity, insulin resistance, dyslipidaemia, nonalcoholic fatty liver disease, type 2 diabetes and cardiovascular disease. However, since increased BCAA amount is observed both in metabolically healthy and obese subjects, a question whether BCAA are mechanistic drivers of insulin resistance and its morbidities or only markers of metabolic dysregulation, still remains open. The beneficial effects of BCAA on body weight and composition, aerobic capacity, insulin secretion and sensitivity demand high catabolic potential toward amino acids and/or adequate BCAA intake. On the opposite, BCAA-related inhibition of lipogenesis and lipolysis enhancement may preclude impairment in insulin sensitivity. Thereby, the following review addresses various strategies pertaining to the modulation of BCAA catabolism and the possible roles of BCAA in energy homeostasis. We also aim to elucidate mechanisms behind the heterogeneity of ramifications associated with BCAA modulation.

Omega-3 fatty acids enhance the beneficial effect of BCAA supplementation on muscle function following eccentric contractions.

Background: This study investigated the combined effect of branched-chain amino acids (BCAA) and fish oil (FO) on muscle damage caused by eccentric contractions (ECCs) of the elbow flexors, with a special focus on muscular function. Methods: Twenty-nine untrained male participants were enrolled in this double-blind, placebo-controlled, parallel study. The participants were randomly assigned to the placebo (PL) group (n = 9), BCAA supplement group (n = 10), and BCAA+FO supplement group (n = 10). The BCAA+FO group consumed eicosapentaenoic acid (EPA) 600 mg and docosahexaenoic acid (DHA) 260 mg per day for 8 weeks, while the BCAA and BCAA+FO groups consumed 9.6 g per day for 3 days prior to and until 5 days after ECCs. Participants performed six sets of 10 ECCs at 100% maximal voluntary contraction (MVC) using dumbbells. Changes in MVC torque, range of motion (ROM), muscle soreness using visual analog scales, upper circumference, muscle thickness, echo intensity, and serum creatine kinase (CK) were assessed before, immediately after, and 1, 2, 3, and 5 days after ECCs. Results: The MVC torque was significantly higher in the BCAA+FO group than in the PL group immediately after ECCs (p < 0.05) but not in the BCAA group. Both BCAA and BCAA+FO groups showed greater ROM and lower muscle soreness than the PL group (p < 0.05). CK was significantly lower in the BCAA group than in the PL group at 5 days after ECCs (p < 0.05). Conclusions: This study reveals that supplementation with BCAA and FO may favorably impact immediate recovery of peak torque production. Alternatively, in comparison to PL group, BCAA supplementation favorably reduces creatine kinase.

Exposure to leucine alters glutamate levels and leads to memory and social impairment in zebrafish.

Maple Syrup Urine Disease (MSUD) is a metabolic disorder characterized by high levels in blood and urine of branched-chain amino acids leucine, isoleucine, and valine and their alpha-ketoacids, by a partial or total blockade in the activity of branched-chain complex alpha-keto acids dehydrogenase. The main symptoms in MSUD occur in the central nervous system, including cognitive deficits, locomotor, poor feeding, seizures, psychomotor delay, and mental retardation, but the mechanisms of neurotoxicity and behavior alteration due to this disease are poorly understood, thus this study aimed at showing the effects of leucine exposure on glutamate levels and behavior in zebrafish. For this, we analyzed the behavior using the social preference test and novel object recognition test, moreover, we analyse the glutamate levels and uptake using scintillation and high-performance liquid chromatography methods. Our results demonstrated a decrease in glutamate levels and uptake, accompanied by memory and social impairment. In conclusion, these results suggest that alterations in glutamate levels can be associated with behavior impairment, however, more studies are necessary to understand the mechanisms for brain damage in MSUD.

Discovery of inhibitors against mycobacterium branched-chain amino acid aminotransferases through in silico screening and experimental evaluation.

Tuberculosis (TB) is one of the most dangerous infectious diseases and is caused by Mycobacterium bovis (Mb) and Mycobacterium tuberculosis (Mt). Branched-chain amino acid aminotransferases (BCATs) were reported to be the key enzyme for methionine synthesis in Mycobacterium. Blocking the methionine synthesis in Mycobacterium can inhibit the growth of Mycobacterium. Therefore, in silico screening of inhibitors can be a good way to develop a potential drug for treating TB. A pyridoxal 5'-phosphate (PLP)-form of Mycobacterium bovis branched-chain amino acid aminotransferases (MbBCAT), an active form of MbBCAT, was constructed manually for docking approximately 150 000 compounds and the free energy was calculated in Autodock Vina. The 10 compounds which had the highest affinity to MbBCAT were further evaluated for their inhibitory effects against MbBCAT. Within the selected compounds, compound 4 (ZINC12359007) was found to be the best inhibitor against MbBCAT with the inhibitory constant Ki of 0·45 µmol l-1 and IC50 of 2·37 µmol l-1 . Our work provides potential candidates to develop effective drugs to prevent TB since the well-known structural information would be beneficial in the structure-based modification and design.

Neuroinflammatory responses following zinc or branched-chain amino acids supplementation in obese rats.

The excessive production of pro-inflammatory mediators, characteristic of obesity, leads to neuroinflammation. Zinc (Zn) and the branched-chain amino acids (BCAA) are supplements known for their immunomodulatory properties. Our goal was to evaluate if Zn or BCAA supplementation can affect long-term recognition memory and neuroinflammatory parameters of obese rats after a high-fat diet (HFD). Three-month-old Wistar rats were divided into six groups: Standard diet (SD) + vehicle; SD + Zn; SD + BCAA; High-fat diet (HFD) + vehicle; HFD + Zn; and HFD + BCAA. Diets were administrated for 19 weeks, Zn (1,2 mg/kg/day) or BCAA (750 mg/kg/day) supplementation was conducted in the last 4 weeks. Long-term recognition memory was evaluated by the novel object recognition test. IL-1ß immunoreactivity in the cortex and hippocampus, and IL-6 levels in the cortex tissue were assessed. Astrogliosis were evaluated through GFAP + cell count and morphological analysis (Sholl Method). Zn supplementation improved object recognition memory in HFD-fed rats, which was not observed following BCAA supplementation. The levels of IL-6 in the cerebral cortex were higher after HFD, which was not diminished after neither supplementation. Obesity also led to increased IL-1ß immunoreactivity in the cerebral cortex and hippocampus, which was reduced by Zn. BCAA supplementation also diminished IL-1ß immunoreactivity, but only in the hippocampus. We also showed that astrocyte reactivity caused by HFD is area-dependent, being the cerebral cortex more susceptible to the diet. Even though BCAA and Zn can affect IL-1ß immunoreactivity and astrocyte morphology, only Zn improved memory. Future studies are needed to clarify the pathways by which Zn improves cognition in obesity.

Exercise Enhances Branched-Chain Amino Acid Catabolism and Decreases Cardiac Vulnerability to Myocardial Ischemic Injury.

Long-term exercise-induced metabolic adaptations occupy a central position in exercise-afforded cardiac benefits. Emerging evidence suggests that branched-chain amino acid (BCAA) catabolic defect contributes to cardiac dysfunction in multiple cardiometabolic diseases. However, the role of BCAA catabolism in exercise-afforded cardiac benefits remains unknown. Here, we show that exercise improves BCAA catabolism and thus reduce cardiac vulnerability to myocardial ischemic injury. Exercise increased circulating BCAA levels in both humans (male adolescent athletes) and mice (following an 8-week swimming intervention). It increased the expression of mitochondrial localized 2C-type serine-threonine protein phosphatase (PP2Cm), a key enzyme in regulating BCAA catabolism, and decreased BCAA accumulation in mouse hearts, indicating an increase in BCAA catabolism. Pharmacological promotion of BCAA catabolism protected the mouse heart against myocardial infarction (MI) induced by permanent ligation of the left descending coronary artery. Although cardiac-specific PP2Cm knockout showed no significant effects on cardiac structural and functional adaptations to exercise, it blunted the cardioprotective effects of exercise against MI. Mechanistically, exercise alleviated BCAA accumulation and subsequently inactivated the mammalian target of rapamycin in MI hearts. These results showed that exercise elevated BCAA catabolism and protected the heart against myocardial ischemic injury, reinforcing the role of exercise in the promotion of cardiac health.

A meta-regression analysis to evaluate the influence of branched-chain amino acids in lactation diets on sow and litter growth performance.

The branched-chain amino acids (BCAA) Ile, Leu, and Val are three dietary essential amino acids for lactating sows; however, effects of dietary BCAA on sow and litter growth performance in the literature are equivocal. Thus, a meta-regression analysis was conducted to evaluate the effects of BCAA and their interactions in lactating sow diets to predict litter growth performance, sow bodyweight change, and sow feed intake. Thirty-four publications that represented 43 trials from 1997 to 2020 were used to develop a database that contained 167 observations. Diets for each trial were reformulated using NRC. 2012. Nutrient requirements of swine. 11th ed. Washington, DC: National Academies Press nutrient loading values in an Excel-based spreadsheet. Amino acids were expressed on a standardized ileal digestible (SID) basis. Regression model equations were developed with the MIXED procedure of SAS (Version 9.4, SAS Institute, Cary, NC) and utilized the inverse of reported squared SEM with the WEIGHT statement to account for heterogeneous errors across studies. Predictor variables were assessed with a step-wise manual forward selection for model inclusion. Additionally, statistically significant (P < 0.05) predictor variables were required to provide an improvement of at least 2 Bayesian information criterion units to be included in the final model. Significant predictor variables within three optimum equations developed for litter ADG included the count of weaned pigs per litter, NE, SID Lys, CP, sow ADFI, Val:Lys, Ile:Lys, and Leu:Val. For sow BW change, significant predictor variables within two developed models included litter size at 24 h, sow ADFI, Leu:Lys, and Ile + Val:Leu. The optimum equation for sow ADFI included Leu:Trp, SID Lys, NE, CP, and Leu:Lys as significant predictor variables. Overall, the prediction equations suggest that BCAA play an important role in litter growth, sow BW change, and feed intake during lactation; however, the influence of BCAA on these criteria is much smaller than that of other dietary components such as NE, SID Lys, sow ADFI, and CP.

The branched-chain amino acids Ile, Leu, and Val are three dietary essential amino acids necessary for both skeletal and milk protein synthesis of lactating sows. Since the late 1990s, sows are producing much larger and heavier litters and commonly receive diets with greater concentrations of crystalline amino acids. This practice unintentionally increases Leu and may create imbalances among the dietary branched-chain amino acids. Nonetheless, sow and litter growth responses to branched-chain amino acids and large neutral amino acids such as Trp are equivocal within the available literature. Therefore, a meta-regression analysis was conducted to evaluate the effects of branched-chain amino acids and their interactions in lactating sow diets to predict litter growth performance, sow bodyweight change, and sow feed intake. The developed models for litter average daily gain suggest that Leu, Ile, and Val impact litter growth, but the effects of branched-chain amino acids are much smaller than the effects of dietary net energy, Lys, and crude protein. Furthermore, the developed models suggest that increasing Leu:Lys and reducing Ile + Val:Leu ratios can positively influence sow bodyweight change during lactation. Additionally, our model suggests that reduced Leu:Trp and increased Leu:Lys positively influence sow feed intake during lactation.