Leucine supplementation improves adiponectin and total cholesterol concentrations despite the lack of changes in adiposity or glucose homeostasis in rats previously exposed to a high-fat diet

BCAAs acutely drive glucose dysregulation and insulin resistance: role of AgRP neurons

BACKGROUND

High-protein diets are often enriched with branched-chain amino acids (BCAAs) known to enhance protein synthesis and provide numerous physiological benefits, but recent studies reveal their association with obesity and diabetes. In support of this, protein or BCAA supplementation is shown to disrupt glucose metabolism while restriction improves it. However, it is not clear if these are primary, direct effects of BCAAs or secondary to other physiological changes during chronic manipulation of dietary BCAAs.

METHODS

Three-month-old C57Bl/6 mice were acutely treated with either vehicle/BCAAs or BT2, a BCAA-lowering compound, and detailed in vivo metabolic phenotyping, including frequent sampling and pancreatic clamps, were conducted.

RESULTS

Using a catheter-guided frequent sampling method in mice, here we show that a single infusion of BCAAs was sufficient to acutely elevate blood glucose and plasma insulin. While pre-treatment with BCAAs did not affect glucose tolerance, a constant infusion of BCAAs during hyperinsulinemic-euglycemic clamps impaired whole-body insulin sensitivity. Similarly, a single injection of BT2 was sufficient to prevent BCAA rise during fasting and markedly improve glucose tolerance in high-fat-fed mice, suggesting that abnormal glycemic control in obesity may be causally linked to high circulating BCAAs. We further show that chemogenetic over-activation of AgRP neurons in the hypothalamus, as present in obesity, significantly impairs glucose tolerance that is completely normalized by acute BCAA reduction. Interestingly, most of these effects were demonstrated only in male, but not in female mice.

CONCLUSION

These findings suggest that BCAAs per se can acutely impair glucose homeostasis and insulin sensitivity, thus offering an explanation for how they may disrupt glucose metabolism in the long-term as observed in obesity and diabetes. Our findings also reveal that AgRP neuronal regulation of blood glucose is mediated through BCAAs, further elucidating a novel mechanism by which brain controls glucose homeostasis.

Branched-chain amino acids prevent obesity by inhibiting the cell cycle in an NADPH-FTO-m6A coordinated manner

Obesity has become a major health crisis in the past decades. Branched-chain amino acids (BCAA), a class of essential amino acids, exerted beneficial health effects with regard to obesity and its related metabolic dysfunction, although the underlying reason is unknown. Here, we show that BCAA supplementation alleviates high-fat diet (HFD)-induced obesity and insulin resistance in mice and inhibits adipogenesis in 3T3-L1 cells. Further, we find that BCAA prevent the mitotic clonal expansion (MCE) of preadipocytes by reducing cyclin A2 (CCNA2) and cyclin-dependent kinase 2 (CDK2) expression. Mechanistically, BCAA decrease the concentration of nicotinamide adenine dinucleotide phosphate (NADPH) in adipose tissue and 3T3-L1 cells by reducing glucose-6-phosphate dehydrogenase (G6PD) expression. The reduced NADPH attenuates the expression of fat mass and obesity-associated (FTO) protein, a well-known m6A demethylase, to increase the N6-methyladenosine (m6A) levels of Ccna2 and Cdk2 mRNA. Meanwhile, the high m6A levels of Ccna2 and Cdk2 mRNA are recognized by YTH N6-methyladenosine RNA binding protein 2 (YTHDF2), which results in mRNA decay and reduction of their protein expressions. Overall, our data demonstrate that BCAA inhibit obesity and adipogenesis by reducing CDK2 and CCNA2 expression via an NADPH-FTO-m6A coordinated manner in vivo and in vitro, which raises a new perspective on the role of m6A in the BCAA regulation of obesity and adipogenesis.

Branched-Chain Amino Acid Metabolism in the Failing Heart

Branched-chain amino acids (BCAAs) are essential amino acids which have critical roles in protein synthesis and energy metabolism in the body. In the heart, there is a strong correlation between impaired BCAA oxidation and contractile dysfunction in heart failure. Plasma and myocardial levels of BCAA and their metabolites, namely branched-chain keto acids (BCKAs), are also linked to cardiac insulin resistance and worsening adverse remodelling in the failing heart. This review discusses the regulation of BCAA metabolism in the heart and the impact of depressed cardiac BCAA oxidation on cardiac energy metabolism, function, and structure in heart failure. While impaired BCAA oxidation in the failing heart causes the accumulation of BCAA and BCKA in the myocardium, recent evidence suggested that the BCAAs and BCKAs have divergent effects on the insulin signalling pathway and the mammalian target of the rapamycin (mTOR) signalling pathway. Dietary and pharmacological interventions that enhance cardiac BCAA oxidation and limit the accumulation of cardiac BCAAs and BCKAs have been shown to have cardioprotective effects in the setting of ischemic heart disease and heart failure. Thus, targeting cardiac BCAA oxidation may be a promising therapeutic approach for heart failure.

Association of branched-chain amino acids with mortality-the Ludwigshafen Risk and Cardiovascular Health (LURIC) study

Branched-chain amino acids (BCAAs) are effectors of metabolic diseases, but their impact on mortality is largely unknown. We investigated the association of BCAA with risk factors and mortality in 2,236 participants of the Ludwigshafen Risk and Cardiovascular Health (LURIC) study using linear and Cox regression. Adiponectin, hemoglobin, C-peptide, hemoglobin A_1c, and homoarginine showed the strongest association with BCAA concentration (all p < 0.001). During a median follow-up of 10.5 years, 715 participants died, including 450 cardiovascular-related deaths. BCAA concentrations were inversely associated with the risk of all-cause and cardiovascular mortality (HR [95% CI] per 1-SD increase in log-BCAA: 0.75 [0.69-0.82] and 0.72 [0.65-0.80], respectively) after adjustment for potential confounders. BCAAs are directly associated with metabolic risk but inversely with mortality in persons with intermediate-to-high cardiovascular risk. Further studies are warranted to evaluate the diagnostic and therapeutic utility of BCAA in the context of cardiovascular diseases.

Aberrant branched-chain amino acid catabolism in cardiovascular diseases

Globally, cardiovascular diseases are the leading cause of death. Research has focused on the metabolism of carbohydrates, fatty acids, and amino acids to improve the prognosis of cardiovascular diseases. There are three types of branched-chain amino acids (BCAAs; valine, leucine, and isoleucine) required for protein homeostasis, energy balance, and signaling pathways. Increasing evidence has implicated BCAAs in the pathogenesis of multiple cardiovascular diseases. This review summarizes the biological origin, signal transduction pathways and function of BCAAs as well as their significance in cardiovascular diseases, including myocardial hypertrophy, heart failure, coronary artery disease, diabetic cardiomyopathy, dilated cardiomyopathy, arrhythmia and hypertension.

Breast Milk MicroRNAs Related to Leptin and Adiponectin Function Can Be Modulated by Maternal Diet and Influence Offspring Phenotype in Rats

There is evidence of the role of milk components in the metabolic programming of offspring. Here, we aimed to investigate the effects of a diet during lactation on breast milk leptin, adiponectin, and related miRNAs’ expression, and their impact on dams and their offspring. Dams were fed a control diet (controls) or a diet enriched with oleic acid, betaine, and leucine (TX) throughout lactation. A TX diet promoted higher leptin at lactation day (LD) five and lower adiponectin on LD15 (vs. controls) in milk, resulting in increased leptin to adiponectin (L/A) ratio throughout lactation. Moreover, TX diet reduced milk levels of miR-27a, miR-103, miR-200a, and miR-222. Concerning TX offspring, higher body fat was early observed and maintained into adult life, accompanied by higher HOMA-IR than controls at three months of age. Offspring body fat content in adulthood correlated positively with milk L/A ratio at LD15 and negatively with miRNAs modulated by the TX diet. In conclusion, maternal diet during lactation can modulate leptin and adiponectin interplay with miRNAs in milk, setting up the metabolic programming of the offspring. Better knowledge about the influence of diet on this process is necessary to promote a healthy adult life in the progeny.

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.

Hepatic effects of rumen-protected branched-chain amino acids with or without propylene glycol supplementation in dairy cows during early lactation

Essential amino acids (EAA) are critical for multiple physiological processes. Branched-chain amino acid (BCAA) supplementation provides energy substrates, promotes protein synthesis, and stimulates insulin secretion in rodents and humans. Most dairy cows face a protein and energy deficit during the first weeks postpartum and utilize body reserves to counteract this shortage. The objective was to evaluate the effect of rumen-protected BCAA (RP-BCAA; 375 g of 27% l-leucine, 85 g of 48% l-isoleucine, and 91 g of 67% l-valine) with or without oral propylene glycol (PG) administration on markers of liver health status, concentrations of nonesterified fatty acids (NEFA) and β-hydroxybutyrate (BHB) in plasma, and liver triglycerides (TG) during the early postpartum period in dairy cows. Multiparous Holstein cows were enrolled in blocks of 3 and randomly assigned to either the control group or 1 of the 2 treatments from calving until 35 d postpartum. The control group (n = 16) received 200 g of dry molasses per cow/d; the RP-BCAA group (n = 14) received RP-BCAA mixed with 200 g of dry molasses per cow/d; the RP-BCAA plus PG (RP-BCAAPG) group (n = 16) received RP-BCAA mixed with 200 g of dry molasses per cow/d, plus 300 mL of PG, once daily from calving until 7 d in milk (DIM). The RP-BCAA and RP-BCAAGP groups, on average (± standard deviation), were predicted to receive a greater supply of metabolizable protein in the form of l-Leu 27.4 ± 3.5 g/d, l-Ile 15.2 ± 1.8 g/d, and l-Val 24.2 ± 2.4 g/d compared with the control cows. Liver biopsies were collected at d 9 ± 4 prepartum and at 5 ± 1 and 21 ± 1 DIM. Blood was sampled 3 times per week from calving until 21 DIM. Milk yield, dry matter intake, NEFA, BHB, EAA blood concentration, serum chemistry, insulin, glucagon, and liver TG and protein abundance of total and phosphorylated branched-chain ketoacid dehydrogenase E1α (p-BCKDH-E1α) were analyzed using repeated measures ANOVA. Cows in the RP-BCAA and RP-BCAAPG groups had lower liver TG and lower activities of aspartate aminotransferase and glutamate dehydrogenase during the first 21 DIM, compared with control. All cows, regardless of treatment, showed an upregulation of p-BCKDH-E1α at d 5 postpartum, compared with levels at 21 d postpartum. Insulin, Met, and Glu blood concentration were greater in RP-BCAA and RP-BCAAPG compared with control during the first 35 DIM. Therefore, the use of RP-BCAA in combination with PG might be a feasible option to reduce hepatic lipidosis in dairy cows during early lactation.

Acute moderate-intensity exercise increases total antioxidant capacity and anti-inflammatory responses in competitive cyclists: The role of adiponectin

High-intensity exercise can elicit acute changes in the biochemical and physiological processes in the body of an athlete, including increased oxidative stress and inflammation. The purpose of this study was to explore the effect of acute moderate-intensity exercise on total antioxidant capacity (TAC) and serum levels of anti-inflammatory adiponectin (APN), and inflammatory markers in competitive cyclists. Ten male cyclists (age 15–26 years, body mass index 19.4–24.7 kg/m2) participated in this study. Each subject performed the maximal oxygen uptake test (VO2peak) and completed a 10-min cycling exercise at a workload of 50% of the peak of VO2peak. Blood samples were collected on three different occasions: after an overnight fasting and at the exercise workloads of 50% and 100% VO2peak. We measured APN, TAC, inflammatory markers as well as assessed nutrient and energy intake for each participant. Baseline concentration of serum APN (10.92 µg/mL) significantly increased at 50% and at 100% VO2peak. In addition, TAC also increased after acute exercise (0.079 vs 0.093 nmol/µL). The concentration of APN at 50% VO2peak positively correlated with the CRP ( r = 0.640, p = 0.046) and negatively correlated with TNF-α ( r = −0.696, p = 0.025). This test showed that short (10 min) and medium-intensity (50% VO2peak) exercise activity in trained athletes evoked beneficial antioxidant and anti-inflammatory responses. Importantly, this response correlates with the increase in APN levels thereby showing that highly trained individuals have beneficial responses originating from adipose tissue. Our observations show that a short training at moderate activity can be an important preservative strategy during the recovery training period.

Modulation effects of black-vinegar-based supplement against a high-fat dietary habit: antiobesity/hypolipidemic, antioxidative, and energy-metabolism effects

BACKGROUND

An imbalanced fat or excess energy intake always results in obesity and increased serum/liver lipids, thus leading to metabolic syndromes. Given the bioactive components in black vinegar (BV), such as branched amino acids, phenolic profile, and mineral contents, we investigated the antiobesity effects of BV-based supplements in rats fed a high-fat diet (HFD).

RESULTS

HFD (30% fat, w/w) feeding increased (P < 0.05) body weight, weight gains, weights of livers and mesenteric, epididymal, and perirenal adipose tissues, and serum/liver triglyceride levels relative to those of rats fed a normal diet (4% fat, w/w; CON). These increased values were ameliorated (P < 0.05) by supplementing with BV-based supplements but were still higher (P < 0.05) than those of CON rats. The increased areas of perirenal adipocytes in rats fed with an HFD were also decreased (P < 0.05) by supplementing with BV-based supplements, which might result from an upregulation (P < 0.05) of 5'-adenosine monophosphate-activated protein kinase (AMPK), carnitine palmitoyltransferase-1 (CPT1), and uncoupling protein-2 (UCP2) in the perirenal adipose tissues. A similar effect was observed for AMPK, peroxisome proliferator-activated receptor alpha, retinoid X receptor alpha, CPT1, and UCP2 gene and protein levels in livers (P < 0.05). Generally, BV-based supplements increased the fecal triglyceride, cholesterol, and bile acid levels of rats fed with an HFD, which partially contribute to the lipid-lowering effects. Furthermore, BV-based supplements increased (P < 0.05) hepatic Trolox equivalent antioxidant capacity and lowered (P < 0.05) serum/liver thiobarbituric acid reactive substances values in HFD-fed rats.

CONCLUSION

In a chronic high-fat dietary habit, the food-grade BV-based supplement is a good daily choice to ameliorate obesity and its associated comorbidities. © 2020 Society of Chemical Industry.

Leucine and isoleucine have similar effects on reducing lipid accumulation, improving insulin sensitivity and increasing the browning of WAT in high-fat diet-induced obese mice

Leucine (Leu) and isoleucine (Ile) have similar effects in the management of obesity and related disorders.

Integrated application of multi-omics provides insights into cold stress responses in pufferfish Takifugu fasciatus

BACKGROUND

T. fasciatus (Takifugu fasciatus) faces the same problem as most warm water fish: the water temperature falls far below the optimal growth temperature in winter, causing a massive death of T. fasciatus and large economic losses. Understanding of the cold-tolerance mechanisms of this species is still limited. Integrated application of multi-omics research can provide a wealth of information to help us improve our understanding of low-temperature tolerance in fish.

RESULTS

To gain a comprehensive and unbiased molecular understanding of cold-tolerance in T. fasciatus, we characterized mRNA-seq and metabolomics of T. fasciatus livers using Illumina HiSeq 2500 and UHPLC-Q-TOF MS. We identified 2544 up-regulated and 2622 down-regulated genes in the liver of T. fasciatus. A total of 40 differential metabolites were identified, including 9 down-regulated and 31 up-regulated metabolites. In combination with previous studies on proteomics, we have established an mRNA-protein-metabolite interaction network. There are 17 DEMs (differentially-expressed metabolites) and 14 DEGs-DEPs (differentially co-expressed genes and proteins) in the interaction network that are mainly involved in fatty acids metabolism, membrane transport, signal transduction, and DNA damage and defense. We then validated a number of genes in the interaction network by qRT-PCR. Additionally, a number of SNPs (single nucleotide polymorphisms) were revealed through the transcriptome data. These results provide key information for further understanding of the molecular mechanisms of T. fasciatus under cold stress.

CONCLUSION

The data generated by integrated application of multi-omics can facilitate our understanding of the molecular mechanisms of fish response to low temperature stress. We have not only identified potential genes and SNPs involved in cold tolerance, but also show that some nutrient metabolites may be added to the diet to help the overwintering of T. fasciatus.

Metabolomics of Type 1 and Type 2 Diabetes

Type 1 and type 2 diabetes mellitus (DM) are chronic diseases that affect nearly 425 million people worldwide, leading to poor health outcomes and high health care costs. High-throughput metabolomics screening can provide vital insight into the pathophysiological pathways of DM and help in managing its effects. The primary aim of this study was to contribute to the understanding and management of DM by providing reliable evidence of the relationships between metabolites and type 1 diabetes (T1D) and metabolites and type 2 diabetes (T2D). Information for the study was obtained from the PubMed, MEDLINE, and EMBASE databases, and leads to additional articles that were obtained from the reference lists of the studies examined. The results from the selected studies were used to assess the relationships between diabetes (T1D and/or T2D) and metabolite markers—such as glutamine, glycine, and aromatic amino acids—in patients. Seventy studies were selected from the three databases and from the reference lists in the records retrieved. All studies explored associations between various metabolites and T1D or T2D. This review identified several plasma metabolites associated with T2D prediabetes and/or T1D and/or T2D in humans. The evidence shows that metabolites such as glucose, fructose, amino acids, and lipids are typically altered in individuals with T1D and T2D. These metabolites exhibit significant predictive associations with T2D prediabetes, T1D, and/or T2D. The current review suggests that changes in plasma metabolites can be identified by metabolomic techniques and used to identify and analyze T1D and T2D biomarkers. The results of the metabolomic studies can be used to help create effective interventions for managing these diseases.

Effect of rumen-protected branched-chain amino acid supplementation on production- and energy-related metabolites during the first 35 days in milk in Holstein dairy cows

Essential AA are critical for multiple physiological processes. Branched-chain AA (BCAA) supplementation has beneficial effects on body weight, lipogenesis, and insulin resistance in several species. The BCAA are used for milk and body protein synthesis as well as being oxidized by the tricarboxylic acid cycle to produce ATP during catabolic states. The objective was to evaluate the effect of rumen-protected BCAA (375 g of 27% l-Leu, 85 g of 48% l-Ile, and 91 g of 67% l-Val) with or without propylene glycol (PG) oral administration on milk production, dry matter intake, nonesterified fatty acids, β-hydroxybutyrate, and plasma urea nitrogen during the first 35 d in milk (DIM) in dairy cattle. Multiparous Holstein cows were enrolled in blocks of three 28 d before expected calving and assigned randomly to either the control or 1 of 2 treatments. The control (n = 26) received 200 g/d of dry molasses, the BCAA treatment (n = 23) received BCAA mixed with 200 g/d of dry molasses from calving until 35 DIM, and the BCAA plus PG (BCAAPG) treatment (n = 25) received BCAA mixed with 200 g/d of dry molasses from calving until 35 DIM plus 300 mL of PG once daily from calving until 7 DIM. Postpartum, dry matter intake least squares means (LSM; 95% confidence interval) were 20.7 (19.9, 21.7), 21.3 (20.4, 22.3), and 21.9 (20.9, 22.8) kg for control, BCAA, and BCAAPG, respectively. Milk yield (1-35 DIM) LSM were 41.7 (39.4, 44.0), 42.7 (40.3, 45.0), and 43.7 (41.4, 46.0) kg for control, BCAA, and BCAAPG, respectively. Energy-corrected milk LSM were 50.3 (46.8, 53.7), 52.4 (48.9, 55.8), and 52.9 (49.5, 56.4) kg for control, BCAA, and BCAAPG, respectively. Milk urea nitrogen LSM in milk for control, BCAA, and BCAAPG were 8.60 (8.02, 9.22), 9.70 (9.01, 10.45), and 9.75 (9.08, 10.47) mg/dL. Plasma urea nitrogen concentrations LSM for control, BCAA, and BCAAPG were 8.3 (7.7, 8.9), 10.1 (9.4, 10.9), and 9.6 (9.4, 10.3) mg/dL, respectively. The numbers of plasma samples classified as hyperketonemia were 77, 44, and 57 in control, BCAA, and BCAAPG, respectively. The BCAA supplementation increased plasma urea nitrogen and milk urea nitrogen, free valine concentration in plasma, and decreased hyperketonemia events during the postpartum period.

Resistance training alone or combined with leucine supplementation improves the serum lipid profile of diabetic rats, whereas leucine alone does not

Objectives. Diabetes mellitus is associated with dyslipidemia, which contributes to a higher risk of thrombosis, atherosclerosis and cardiovascular disease. This study evaluated the effects of leucine and resistance training on the serum lipid profile in rats with streptozotocin-induced diabetes for 8 weeks.

Methods. Wistar rats with neonatal streptozotocin-induced diabetes were treated with leucine supplementation (5%) and/or resistance training (3 days per week) for 8 weeks, and divided in DL (diabetic and leucine), DT (diabetic and resistance training group) and DLT (diabetic, leucine and resistance training) groups. Others 2 groups of animals received isonitrogen AIN-93M diet that was defined as a control diet: group D (diabetic untreated) and group C (non-diabetic).

Results. The decrease in serum total cholesterol and increase in high-density lipoprotein cholesterol (HDL-C) was observed in the resistance training-induced diabetic rats when compared with diabetic rats. There was no change in serum lipid profile in leucine-supplemented diabetic rats and no synergistic effect of leucine and resistance training. The fasting glucose levels were reduced in all animals treated compared to D group.

Conclusion. The diabetic trained rats demonstrate a protective effect of resistance training on the serum lipid profile.

Towards the modulation of oxidative damage, apoptosis and tight junction protein in response to dietary leucine deficiency: A likely cause of ROS-induced gill structural integrity impairment

The current study explored the protective effect of leucine on antioxidant status, apoptosis and tight junction damage in the gill of grass carp (Ctenopharyngodon idella Val.). The trial was conducted by feeding grass carp with six graded level of leucine (7.1, 8.9, 11.0, 13.3, 15.2 and 17.1 g kg^-1 diet) for 8 weeks. The fish were fed to apparent satiation 4 times per day. The results indicated that compared with the leucine deficiency group, 8.9-11.3 g leucine kg^-1 diet supplementations decreased protein carbonyl (PC), malondialdehyde (MDA) and ROS contents, which may be partially attributed to the improvement of antioxidant status in the gill by increasing hydroxyl radical capacity and anti-superoxide radicals, glutathione contents and the activities and mRNA levels of Cu/Zn superoxide dismutase (SOD1), glutathione peroxidase (GPx), catalase (CAT), glutathione-S-transferase (GST) and glutathione reductase (GR), that referring to the up-regulation of nuclear factor erythroid 2-related factor 2 (Nrf2) mRNA expression. Moreover, leucine deficiency induced DNA fragmentation via the up-regulation of caspase-3, caspase-8 and caspase-9 expressions and down-regulation of target of rapamycin and ribosomal S6 protein kinase 1 expressions. Furthermore, leucine deficiency increased interleukin-1β (IL-1β), interleukin-8 (IL-8) and tumor necrosis factor-α (TNF-α) mRNA expression and decreased IL-10 and transforming growth factor β (TGF-β), which was partly related to nuclear factor κB (NF-κB) and its inhibitor (IκB). In contrast, the relative mRNA expression of IL-1, IL-8 and TNF-α was down-regulated with 8.9-11.3 g leucine kg^-1 diet supplementations. Finally, the relative mRNA expression of tight junction protein, including occludin, zonula occludens-1, claudin b, claudin 3 and claudin 12 was up-regulated with leucine diet supplementations. Our results indicate that leucine protected the fish gill structural integrity partially because of the inhibition of apoptosis, the improvement of antioxidant status, the regulation of tight junction protein and related signalling molecules mRNA expressions in the fish gill.

Severe energy deficit upregulates leptin receptors, leptin signaling, and PTP1B in human skeletal muscle

In obesity, leptin receptors (OBR) and leptin signaling in skeletal muscle are downregulated. To determine whether OBR and leptin signaling are upregulated with a severe energy deficit, 15 overweight men were assessed before the intervention (PRE), after 4 days of caloric restriction (3.2 kcal·kg body wt−1·day−1) in combination with prolonged exercise (CRE; 8 h walking + 45 min single-arm cranking/day) to induce an energy deficit of ~5,500 kcal/day, and following 3 days of control diet (isoenergetic) and reduced exercise (CD). During CRE, the diet consisted solely of whey protein ( n = 8) or sucrose ( n = 7; 0.8 g·kg body wt−1·day−1). Muscle biopsies were obtained from the exercised and the nonexercised deltoid muscles and from the vastus lateralis. From PRE to CRE, serum glucose, insulin, and leptin were reduced. OBR expression was augmented in all examined muscles associated with increased maximal fat oxidation. Compared with PRE, after CD, phospho-Tyr1141OBR, phospho-Tyr985OBR, JAK2, and phospho-Tyr1007/1008JAK2 protein expression were increased in all muscles, whereas STAT3 and phospho-Tyr705STAT3 were increased only in the arms. The expression of protein tyrosine phosphatase 1B (PTP1B) in skeletal muscle was increased by 18 and 45% after CRE and CD, respectively ( P < 0.05). Suppressor of cytokine signaling 3 (SOCS3) tended to increase in the legs and decrease in the arm muscles (ANOVA interaction: P < 0.05). Myosin heavy chain I isoform was associated with OBR protein expression ( r = −0.75), phospho-Tyr985OBR ( r = 0.88), and phospho-Tyr705STAT3/STAT3 ( r = 0.74). In summary, despite increased PTP1B expression, skeletal muscle OBR and signaling are upregulated by a severe energy deficit with greater response in the arm than in the legs likely due to SOCS3 upregulation in the leg muscles.

NEW & NOTEWORTHY This study shows that the skeletal muscle leptin receptors and their corresponding signaling cascade are upregulated in response to a severe energy deficit, contributing to increase maximal fat oxidation. The responses are more prominent in the arm muscles than in the legs but partly blunted by whey protein ingestion and high volume of exercise. This occurs despite an increase of protein tyrosine phosphatase 1B protein expression, a known inhibitor of insulin and leptin signaling.

Leucine and resistance training improve hyperglycemia, white adipose tissue loss, and inflammatory parameters in an experimental model of type 1 diabetes

BACKGROUND

Loss of white adipose tissue (WAT), associated with type 1 diabetes (DM1), contributes to increased chronic systemic inflammation.

AIM

The aim of this study was to investigate the effects of leucine supplementation and resistance training (RT) in attenuating WAT loss and improving inflammatory parameters and glucose metabolism in DM1 rats.

METHODS

Thirty-two male Wistar rats were distributed into four groups: DA (sedentary and supplemented with non-essential amino acids (NEAA)), DL (sedentary and supplemented with leucine), DTA (submitted to RT and supplemented with NEAA) and DTL (submitted to RT and supplemented with leucine). DM1 was induced by streptozotocin (STZ). An 8-week period of RT consisted of climbing a ladder with a progressively increased load, and supplementation was offered in the feed.

RESULTS

Glycemia, polyphagia and polydipsia were lower in DL, DTA and DTL groups compared with the DA group by approximately 20% ( p<.0001), 28% ( p=.004) and 64% ( p<.0001), respectively. Weight of total WAT and retroperitoneal adipose tissue (RPAT) were higher by approximately 21% ( p=.01) and 54% ( p=.0004), respectively, in DL, DTA and DTL groups compared with DA. However, gene expression of adiponectin and leptin in RPAT was only increased by RT (DTA and DTL) compared with DA and DL by approximately 93% ( p<.0001) and 78% ( p=.0002), respectively. Similarly, the levels of adiponectin in the serum, tissue IL-10 (RPAT) and serum IL-10 were only increased in DTA and DTL compared with DA and DL by approximately 31% ( p=.03), 45% ( p=.0009) and 35% ( p=.003), respectively.

CONCLUSIONS

Both interventions, isolated or together, reduced hyperglycemia and excessive loss of WAT, but RT was the main factor responsible for attenuating inflammation.

Branched-chain amino acids differently modulate catabolic and anabolic states in mammals: a pharmacological point of view

Substantial evidence has been accumulated suggesting that branched-chain amino acid (BCAA) supplementation or BCAA-rich diets have a positive effect on the regulation of body weight, muscle protein synthesis, glucose homeostasis, the ageing process and extend healthspan. Despite these beneficial effects, epidemiological studies have shown that BCAA plasma concentrations and BCAA metabolism are altered in several metabolic disorders, including type 2 diabetes mellitus and cardiovascular diseases. In this review article, we present an overview of the current literature on the different effects of BCAAs in health and disease. We also highlight the results showing the most promising therapeutic effects of dietary BCAA supplementation and discuss how BCAAs can trigger different and even opposite effects, depending on the catabolic and anabolic states of the organisms. Moreover, we consider the effects of BCAAs when metabolism is abnormal, in the presence of a mixture of different anabolic and catabolic signals. These unique pharmacodynamic properties may partially explain some of the markedly different effects found in BCAA supplementation studies. To predict accurately these effects, the overall catabolic/anabolic status of patients should be carefully considered. In wider terms, a correct modulation of metabolic disorders would make nutraceutical interventions with BCAAs more effective.

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

Chronic leucine supplementation improves lipid metabolism in C57BL/6J mice fed with a high-fat/cholesterol diet

Background

Leucine supplementation has been reported to improve lipid metabolism. However, lipid metabolism in adipose tissues and liver has not been extensively studied for leucine supplementation in mice fed with a high-fat/cholesterol diet (HFCD).

Design

C57BL/6J mice were fed a chow diet, HFCD, HFCD supplemented with 1.5% leucine (HFCD+1.5% Leu group) or 3% leucine (HFCD+3% Leu group) for 24 weeks. The body weight, peritoneal adipose weight, total cholesterol (TC), triglyceride in serum and liver, and serum adipokines were analyzed. In addition, expression levels of proteins associated with hepatic lipogenesis, adipocyte lipolysis, and white adipose tissue (WAT) browning were determined.

Results

Mice in the HFCD group developed obesity and deteriorated lipid metabolism. Compared with HFCD, leucine supplementation lowered weight gain and TC levels in circulation and the liver without changing energy intake. The decrease in body fat was supported by histological examination in the WAT and liver. Furthermore, serum levels of proinflammatory adipokines, such as leptin, IL-6, and tumor necrosis factor-alpha, were significantly decreased by supplemented leucine. At the protein level, leucine potently decreased the hepatic lipogenic enzymes (fatty acid synthase and acetyl-coenzyme A carboxylase) and corresponding upstream proteins. In epididymal WAT, the reduced expression levels of two major lipases by HFCD, namely phosphorylated hormone-sensitive lipase and adipose triglyceride lipase, were reversed when leucine was supplemented. Uncoupling protein 1, β3 adrenergic receptors, peroxisome proliferator-activated receptor g coactivator-1α, and fibroblast growth factor 21 were involved in the thermogenic program and WAT browning. Leucine additionally upregulated their protein expression in both WAT and interscapular brown adipose tissue.

Conclusion

This study demonstrated that chronic leucine supplementation reduced the body weight and improved the lipid profile of mice fed with a HFCD. This beneficial effect was ascribed to hepatic lipogenesis, adipocyte lipolysis, and WAT browning.

The Emerging Role of Branched-Chain Amino Acids in Insulin Resistance and Metabolism

Insulin is required for maintenance of glucose homeostasis. Despite the importance of insulin sensitivity to metabolic health, the mechanisms that induce insulin resistance remain unclear. Branched-chain amino acids (BCAAs) belong to the essential amino acids, which are both direct and indirect nutrient signals. Even though BCAAs have been reported to improve metabolic health, an increased BCAA plasma level is associated with a high risk of metabolic disorder and future insulin resistance, or type 2 diabetes mellitus (T2DM). The activation of mammalian target of rapamycin complex 1 (mTORC1) by BCAAs has been suggested to cause insulin resistance. In addition, defective BCAA oxidative metabolism might occur in obesity, leading to a further accumulation of BCAAs and toxic intermediates. This review provides the current understanding of the mechanism of BCAA-induced mTORC1 activation, as well as the effect of mTOR activation on metabolic health in terms of insulin sensitivity. Furthermore, the effects of impaired BCAA metabolism will be discussed in detail.

The Ratio of Dietary Branched-Chain Amino Acids is Associated with a Lower Prevalence of Obesity in Young Northern Chinese Adults: An Internet-Based Cross-Sectional Study

This study aims to examine the association between the ratio of dietary branched chain amino acids (BCAA) and risk of obesity among young northern Chinese adults. A total of 948 randomly recruited participants were asked to finish our internet-based dietary questionnaire for the Chinese (IDQC). Associations between dietary BCAA ratio and prevalence of overweight/obesity and abdominal obesity were analyzed. Furthermore, 90 subjects were randomly selected to explore the possible mechanism. Dietary BCAA ratio in obese participants was significantly lower than non-obese participants. We found negative correlations between the ratio of dietary BCAA and body mass index (BMI) (r = −0.197, p < 0.001) or waist circumference (r = −0.187, p < 0.001). Compared with those in the first quartile, the multivariable-adjusted OR (95% CI) of the 3rd and 4th quartiles of dietary BCAA ratio for overweight/obesity were 0.508 (0.265–0.972) and 0.389 (0.193–0.783), respectively (all p < 0.05). After stratification by gender, the significance still existed in the 3rd and 4th quartile in males and the 4th quartile in females. For abdominal obesity, the multivariable-adjusted OR (95% CI) of the 3rd and 4th quartile of dietary BCAA ratio were 0.351 (0.145–0.845) and 0.376 (0.161–0.876), respectively (all p < 0.05). This significance was stronger in males. Further studies indicated that dietary BCAA ratio was inversely associated with 2-h postprandial glucose (2 h-PG) and status of inflammation. In conclusion, a higher ratio of dietary BCAA is inversely associated with prevalence of obesity, postprandial glucose and status of inflammation in young northern Chinese adults.

Ketoacid Supplementation Partially Improves Metabolic Parameters in Patients on Peritoneal Dialysis

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BACKGROUND

A low protein diet supplemented with ketoacids has been shown to improve the metabolic profile, including insulin resistance, in patients with chronic kidney disease (CKD), but whether ketoacids alone exert similar effects is unknown. In this prospective randomized controlled trial, we aimed to evaluate the effects of ketoacid supplementation on insulin resistance, systemic inflammation, oxidative stress and endothelial dysfunction among 100 CKD patients undergoing peritoneal dialysis (PD). ♦

METHODS

Patients from one Chinese PD center were randomly assigned to take ketoacids (12 tablets per day) (n = 50) versus a control group (n = 50) for 6 months in an open-label parallelarm design. Daily protein intake of 0.8 - 1.2 g/kg/d and daily energy intake of 25 - 35 kcal/kg/d was prescribed to both groups. Insulin resistance was evaluated using homeostatic model assessment (HOMA-IR) index as the primary outcome. We assessed systemic inflammation using high-sensitive C-reactive protein (hs-CRP) and interleukin-6 (IL-6), oxidative stress using plasma oxidized low density lipoprotein (oxLDL), adipokines using leptin and adiponectin and endothelial dysfunction using serum soluble intercellular adhesion molecule-1 (sICAM) and soluble vascular adhesion molecule-1 (sVCAM) as secondary outcomes. ♦

RESULTS

There were no significant differences in baseline characteristics between the 2 groups except a slightly higher age in patients assigned to the intervention. A total of 89% of participants completed the 6-month intervention. There was no significant difference in the change of HOMA-IR values from baseline between groups after adjusting for baseline age, gender, body mass index and HOMA-IR. For secondary outcomes, hs-CRP varied significantly between groups (p = 0.02), increasing over time for the control group while remaining stable for the ketoacid group. Similarly, the leptin/adiponectin ratio (LAR) differed between groups (p < 0.001), remaining stable in the ketoacid group but increasing in the control group. ♦

CONCLUSION

Ketoacid therapy administered for 6 months had no effect on HOMA-IR but resulted in improvements in hs-CRP and LAR, suggesting metabolic benefit. Future studies are needed to confirm these results and any potential benefit in vascular health of PD patients.

Biocompounds Attenuating the Development of Obesity and Insulin Resistance Produced by a High-fat Sucrose Diet

The use of biocompounds as agents with potential anti-obesity effects might be a feasible alternative to the prescription of traditional drugs in the near future. The goal of the present study was to screen five different compounds in relation to their ability to prevent body weight gain and ameliorate obesity-associated metabolic impairments, namely insulin resistance. For this purpose, seventy Wistar rats were randomly assigned into seven experimental groups. A standard diet-fed control group (control, n=10); a high-fat, high-sucrose diet-fed group (HFS, n=10) and five experimental groups which were fed the HFS diet supplemented with one of the following biocompounds; curcumin (100 mg/kg bw, n=10), chlorogenic acid (50 mg/kg bw, n=10), coumaric acid (100 mg/kg bw, n=10), naringin (100 mg/kg bw, n=10) and leucine (1 % of diet, n=10). These results confirm the effectiveness of all the compounds to reduce significantly food efficiency, despite the significant higher food intake. Moreover, visceral fat mass percentage was significantly decreased after naringin and coumaric acid supplementation. In fact, this finding might be related to the considerable amelioration of HOMA-IR index detected in naringin-treated animals. A significant reduction in serum insulin levels and an improvement in the intraperitoneal glucose tolerance test and AUC were found in leucine- and coumaric acid-treated rats, respectively. In summary, the tested biocompounds, particularly naringin, coumaric acid and leucine, showed potential benefits in the prevention of obesity-related complications in rats, at least at the proved doses.

Leucine supplementation improves leptin sensitivity in high-fat diet fed rats

Background

Several studies have reported the favorable effect of leucine supplementation on insulin resistance or insulin sensitivity. However, whether or not leucine supplementation improves leptin sensitivity remains unclear.

Design

Forty-eight male Sprague-Dawley rats were fed with either a high-fat diet (HFD) or HFD supplemented with 1.5, 3.0, and 4.5% leucine for 16 weeks. At the end of the experiment, serum leptin level was measured by ELISA, and leptin receptor (ObR) in the hypothalamus was examined by immunohistochemistry. The protein expressions of ObR and leptin-signaling pathway in adipose tissues were detected by western blot.

Results

No significant differences in body weight and food/energy intake existed among the four groups. Serum leptin levels were significantly lower, and ObR expression in the hypothalamus and adipose tissues was significantly higher in the three leucine groups than in the control group. These phenomena suggested that leptin sensitivity was improved in the leucine groups. Furthermore, the expressions of JAK2 and STAT3 (activated by ObR) were significantly higher, and that of SOCS3 (inhibits leptin signaling) was significantly lower in the three leucine groups than in the control group.

Conclusions

Leucine supplementation improves leptin sensitivity in rats on HFD likely by promoting leptin signaling.

Reviewing the Effects of L-Leucine Supplementation in the Regulation of Food Intake, Energy Balance, and Glucose Homeostasis

Leucine is a well-known activator of the mammalian target of rapamycin (mTOR). Because mTOR signaling regulates several aspects of metabolism, the potential of leucine as a dietary supplement for treating obesity and diabetes mellitus has been investigated. The objective of the present review was to summarize and discuss the available evidence regarding the mechanisms and the effects of leucine supplementation on the regulation of food intake, energy balance, and glucose homeostasis. Based on the available evidence, we conclude that although central leucine injection decreases food intake, this effect is not well reproduced when leucine is provided as a dietary supplement. Consequently, no robust evidence indicates that oral leucine supplementation significantly affects food intake, although several studies have shown that leucine supplementation may help to decrease body adiposity in specific conditions. However, more studies are necessary to assess the effects of leucine supplementation in already-obese subjects. Finally, although several studies have found that leucine supplementation improves glucose homeostasis, the underlying mechanisms involved in these potential beneficial effects remain unknown and may be partially dependent on weight loss.

Branched-chain amino acids in metabolic signalling and insulin resistance

Branched-chain amino acids (BCAAs) are important nutrient signals that have direct and indirect effects. Frequently, BCAAs have been reported to mediate antiobesity effects, especially in rodent models. However, circulating levels of BCAAs tend to be increased in individuals with obesity and are associated with worse metabolic health and future insulin resistance or type 2 diabetes mellitus (T2DM). A hypothesized mechanism linking increased levels of BCAAs and T2DM involves leucine-mediated activation of the mammalian target of rapamycin complex 1 (mTORC1), which results in uncoupling of insulin signalling at an early stage. A BCAA dysmetabolism model proposes that the accumulation of mitotoxic metabolites (and not BCAAs per se) promotes β-cell mitochondrial dysfunction, stress signalling and apoptosis associated with T2DM. Alternatively, insulin resistance might promote aminoacidaemia by increasing the protein degradation that insulin normally suppresses, and/or by eliciting an impairment of efficient BCAA oxidative metabolism in some tissues. Whether and how impaired BCAA metabolism might occur in obesity is discussed in this Review. Research on the role of individual and model-dependent differences in BCAA metabolism is needed, as several genes (BCKDHA, PPM1K, IVD and KLF15) have been designated as candidate genes for obesity and/or T2DM in humans, and distinct phenotypes of tissue-specific branched chain ketoacid dehydrogenase complex activity have been detected in animal models of obesity and T2DM.

Obesity, inflammation, and insulin resistance

White adipose tissue (WAT) is considered an endocrine organ. When present in excess, WAT can influence metabolism via biologically active molecules. Following unregulated production of such molecules, adipose tissue dysfunction results, contributing to complications associated with obesity. Previous studies have implicated pro- and anti-inflammatory substances in the regulation of inflammatory response and in the development of insulin resistance. In obese individuals, pro-inflammatory molecules produced by adipose tissue contribute to the development of insulin resistance and increased risk of cardiovascular disease. On the other hand, the molecules with anti-inflammatory action, that have been associated with the improvement of insulin sensitivity, have your decreased production. Imbalance of these substances contributes significantly to metabolic disorders found in obese individuals. The current review aims to provide updated information regarding the activity of biomolecules produced by WAT.

L-leucine supplementation worsens the adiposity of already obese rats by promoting a hypothalamic pattern of gene expression that favors fat accumulation

Several studies showed that l-leucine supplementation reduces adiposity when provided before the onset of obesity. We studied rats that were exposed to a high-fat diet (HFD) for 10 weeks before they started to receive l-leucine supplementation. Fat mass was increased in l-leucine-supplemented rats consuming the HFD. Accordingly, l-leucine produced a hypothalamic pattern of gene expression that favors fat accumulation. In conclusion, l-leucine supplementation worsened the adiposity of rats previously exposed to HFD possibly by central mechanisms.

Effects of whey protein and leucine supplementation on insulin resistance in non-obese insulin-resistant model rats

OBJECTIVE

Whey protein (WP) has been reported to reduce body weight gain and improve glucose metabolism in obese individuals. This study aims to assess and compare the effects of WP and its hydrolysate-leucine (Leu) supplementation in non-obese, insulin-resistant (IR) rat models, particularly the effects on insulin sensitivity, lipid profile, and antioxidant activity.

METHODS

Wistar rats were fed a diet consisting of 38.5% fat for 12 wk and 51.3% fat for an additional 4 wk to establish non-obese IR rats. The IR rats were then switched to regular AIN-93 diet containing 0% WP, 5% WP, 15% WP or 1.6% Leu for 8 wk. The Leu content was the same in the 15% WP and 1.6% Leu groups based on high-performance liquid chromatography. The IR rats' body weight, fasting blood glucose, fasting insulin, and homeostasis model assessment-insulin resistance were measured before and after supplementation. An oral glucose tolerance test was performed after supplementation. Body composition, plasma concentrations of the lipids profile, and antioxidant index also were analyzed.

RESULTS

No significant difference was observed in body weight, energy intake, and fasting blood glucose in the non-obese IR rats at the end of the experiment. Compared with the 0% WP group, the fasting insulin and homeostasis model assessment-insulin resistance significantly decreased in the 15% WP and 1.6% Leu groups. Furthermore, the blood glucose area under the curve of the oral glucose tolerance test was significantly less in the 15% WP and 1.6% Leu groups. There were no differences in the lipids profile, except for the increase in the high-density lipoprotein cholesterol in the 15% WP and 1.6% Leu groups. For the antioxidant index, the 15% WP group had significantly increased plasma levels for total antioxidation capacity, superoxide dismutase, and glutathione, and a decreased malondialdehyde concentration. The 1.6% Leu group was shown to have the same effect as the 15% WP group, except for the glutathione.

CONCLUSION

Our findings demonstrate that the supplementation of WP and Leu may improve IR and antioxidant stress without resulting in changes in body weight and energy intake in non-obese IR rats.

Beyond the role of dietary protein and amino acids in the prevention of diet-induced obesity

High-protein diets have been shown to prevent the development of diet-induced obesity and can improve associated metabolic disorders in mice. Dietary leucine supplementation can partially mimic this effect. However, the molecular mechanisms triggering these preventive effects remain to be satisfactorily explained. Here we review studies showing a connection between high protein or total amino nitrogen intake and obligatory water intake. High amino nitrogen intake may possibly lower lipid storage, and prevent insulin resistance. Suggestions are made for further systematical studies to explore the relationship between water consumption, satiety, and energy expenditure. Moreover, these examinations should better distinguish between leucine-specific and unspecific effects. Research in this field can provide important information to justify dietary recommendations and strategies in promoting long-term weight loss and may help to reduce health problems associated with the comorbidities of obesity.

Oral leucine supplementation is sensed by the brain but neither reduces food intake nor induces an anorectic pattern of gene expression in the hypothalamus

Leucine activates the intracellular mammalian target of the rapamycin (mTOR) pathway, and hypothalamic mTOR signaling regulates food intake. Although central infusion of leucine reduces food intake, it is still uncertain whether oral leucine supplementation is able to affect the hypothalamic circuits that control energy balance. We observed increased phosphorylation of p70s6k in the mouse hypothalamus after an acute oral gavage of leucine. We then assessed whether acute oral gavage of leucine induces the activation of neurons in several hypothalamic nuclei and in the brainstem. Leucine did not induce the expression of Fos in hypothalamic nuclei, but it increased the number of Fos-immunoreactive neurons in the area postrema. In addition, oral gavage of leucine acutely increased the 24 h food intake of mice. Nonetheless, chronic leucine supplementation in the drinking water did not change the food intake and the weight gain of ob/ob mice and of wild-type mice consuming a low- or a high-fat diet. We assessed the hypothalamic gene expression and observed that leucine supplementation increased the expression of enzymes (BCAT1, BCAT2 and BCKDK) that metabolize branched-chain amino acids. Despite these effects, leucine supplementation did not induce an anorectic pattern of gene expression in the hypothalamus. In conclusion, our data show that the brain is able to sense oral leucine intake. However, the food intake is not modified by chronic oral leucine supplementation. These results question the possible efficacy of leucine supplementation as an appetite suppressant to treat obesity.

Leucine improves protein nutritional status and regulates hepatic lipid metabolism in calorie-restricted rats

Several studies have highlighted the potential of leucine supplementation for the treatment of metabolic diseases including type 2 diabetes and obesity. Caloric restriction is a common approach to improve the health in diabetic and obese subjects. However, very few studies assessed the effects of leucine supplementation in calorie-restricted animals. Rats were subjected to a 30% calorie-restricted diet for 6 weeks to study the effects of leucine supplementation on protein status markers and lipid metabolism. Caloric restriction reduced the body weight. However, increased leucine intake preserved body lean mass and protein mass and improved protein anabolism as indicated by the increased circulating levels of albumin and insulin-like growth factor-1 (IGF-1), and the liver expression of albumin and IGF-1 messenger RNA. Leucine supplementation also increased the circulating levels of interleukin-6 and leptin but did not affect the tumour necrosis factor-α and monocyte chemotactic protein-1 concentrations. Ketone bodies were increased in rats consuming a leucine-rich diet, but we observed no changes in cholesterol or triglycerides concentrations. Caloric restriction reduced the liver expression of peroxisome proliferator activated receptor-α and glucose-6-phosphatase, whereas leucine supplementation increased the liver expression of 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-CoA) reductase and sterol regulatory element-binding transcription factor 1. A leucine-rich diet during caloric restriction preserved whole body protein mass and improved markers of protein anabolism. In addition, leucine modulated the hepatic lipid metabolism. These results indicate that increased leucine intake may be useful in preventing excessive protein waste in conditions of large weight loss.

Leucine supplementation combined with resistance exercise improves the plasma lipid profile of dexamethasone-treated rats

The impact of leucine supplementation and resistance exercise (RE) on plasma lipid profile was evaluated in adult rats treated with dexamethasone, an experimental model of dyslipidemia. Total cholesterol did not differ among groups. Furthermore, leucine supplementation did not promote improvement in the plasma total cholesterol and LDL-c of the animals. However, plasma TG and VLDL-c were significantly decreased and HDL-c increased after 7 days of leucine supplementation combined with RE. In conclusion, leucine supplementation combined with RE, but not isolated, improved the plasma lipid profile of dexamethasone-induced dyslipidemic rats.