Muscle carnosine metabolism and beta-alanine supplementation in relation to exercise and training

The Role of Zinc in the Development of Vascular Dementia and Parkinson's Disease and the Potential of Carnosine as Their Therapeutic Agent

Synaptic zinc ions (Zn2+) play an important role in the development of vascular dementia (VD) and Parkinson's disease (PD). In this article, we reviewed the current comprehension of the Zn2+-induced neurotoxicity that leads to the pathogenesis of these neuronal diseases. Zn2+-induced neurotoxicity was investigated by using immortalised hypothalamic neurons (GT1-7 cells). This cell line is useful for the development of a rapid and convenient screening system for investigating Zn2+-induced neurotoxicity. GT1-7 cells were also used to search for substances that prevent Zn2+-induced neurotoxicity. Among the tested substances was a protective substance in the extract of Japanese eel (Anguilla japonica), and we determined its structure to be like carnosine (β-alanylhistidine). Carnosine may be a therapeutic drug for VD and PD. Furthermore, we reviewed the molecular mechanisms that involve the role of carnosine as an endogenous protector and its protective effect against Zn2+-induced cytotoxicity and discussed the prospects for the future therapeutic applications of this dipeptide for neurodegenerative diseases and dementia.

Carnosine regulation of intracellular pH homeostasis promotes lysosome-dependent tumor immunoevasion

Tumor cells and surrounding immune cells undergo metabolic reprogramming, leading to an acidic tumor microenvironment. However, it is unclear how tumor cells adapt to this acidic stress during tumor progression. Here we show that carnosine, a mobile buffering metabolite that accumulates under hypoxia in tumor cells, regulates intracellular pH homeostasis and drives lysosome-dependent tumor immune evasion. A previously unrecognized isoform of carnosine synthase, CARNS2, promotes carnosine synthesis under hypoxia. Carnosine maintains intracellular pH (pHi) homeostasis by functioning as a mobile proton carrier to accelerate cytosolic H+ mobility and release, which in turn controls lysosomal subcellular distribution, acidification and activity. Furthermore, by maintaining lysosomal activity, carnosine facilitates nuclear transcription factor X-box binding 1 (NFX1) degradation, triggering galectin-9 and T-cell-mediated immune escape and tumorigenesis. These findings indicate an unconventional mechanism for pHi regulation in cancer cells and demonstrate how lysosome contributes to immune evasion, thus providing a basis for development of combined therapeutic strategies against hepatocellular carcinoma that exploit disrupted pHi homeostasis with immune checkpoint blockade.

Combined Exercise Training and Nutritional Interventions or Pharmacological Treatments to Improve Exercise Capacity and Body Composition in Chronic Obstructive Pulmonary Disease: A Narrative Review

Chronic obstructive pulmonary disease (COPD) is a chronic respiratory disease that is associated with significant morbidity, mortality, and healthcare costs. The burden of respiratory symptoms and airflow limitation can translate to reduced physical activity, in turn contributing to poor exercise capacity, muscle dysfunction, and body composition abnormalities. These extrapulmonary features of the disease are targeted during pulmonary rehabilitation, which provides patients with tailored therapies to improve the physical and emotional status. Patients with COPD can be divided into metabolic phenotypes, including cachectic, sarcopenic, normal weight, obese, and sarcopenic with hidden obesity. To date, there have been many studies performed investigating the individual effects of exercise training programs as well as nutritional and pharmacological treatments to improve exercise capacity and body composition in patients with COPD. However, little research is available investigating the combined effect of exercise training with nutritional or pharmacological treatments on these outcomes. Therefore, this review focuses on exploring the potential additional beneficial effects of combinations of exercise training and nutritional or pharmacological treatments to target exercise capacity and body composition in patients with COPD with different metabolic phenotypes.

Effect of carnosine synthesis precursors in the diet on jejunal metabolomic profiling and biochemical compounds in slow-growing Korat chicken

The slow-growing Korat chicken (KR) has been developed to provide an alternative breed for smallholder farmers in Thailand. Carnosine enrichment in the meat can distinguish KR from other chicken breeds. Therefore, our aim was to investigate the effect of enriched carnosine synthesis, obtained by the β-alanine and L-histidine precursor supplementation in the diet, on changes to metabolomic profiles and biochemical compounds in slow-growing KR jejunum tissue. Four hundred 21-day-old female KR chickens were divided into 4 experimental groups: a group with a basal diet, a group with a basal diet supplemented with 1.0% β-alanine, 0.5% L-histidine, and a mix of 1.0% β-alanine and 0.5% L-histidine. The feeding trial lasted 70 d. Ten randomly selected chickens from each group were slaughtered. Metabolic profiles were analyzed using proton nuclear magnetic resonance spectroscopy. In total, 28 metabolites were identified. Significant changes in the concentrations of these metabolites were detected between the groups. Partial least squares discriminant analysis was used to distinguish the metabolites between the experimental groups. Based on the discovered metabolites, 34 potential metabolic pathways showed differentiation between groups, and 8 pathways (with impact values higher than 0.05, P < 0.05, and FDR < 0.05) were affected by metabolite content. In addition, biochemical changes were monitored using synchrotron radiation-based Fourier transform infrared microspectroscopy. Supplementation of β-alanine alone in the diet increased the β-sheets and decreased the α-helix content in the amide I region, and supplementation of L-histidine alone in the diet also increased the β-sheets. Furthermore, the relationship between metabolite contents and biochemical compounds were confirmed using principal component analysis (PCA). Results from the PCA indicated that β-alanine and L-histidine precursor group was highly positively correlated with amide I, amide II, creatine, tyrosine, valine, isoleucine, and aspartate. These findings can help to understand the relationships and patterns between the spectral and metabolic processes related to carnosine synthesis.

Effect of a sustained-release formulation of β-alanine on laboratory parameters and paresthesia in recreational trained men: a randomized double-blind placebo-controlled study

Introduction

Beta-alanine is a non-essential amino acid that has been a focus of increasing research by its role as ergogenic aid to improve muscle performance.

Methods

A randomized, double-blind and controlled trial was conducted to determine the effect of a nutritional supplement of a sustained-release formulation of β-alanine in recreational trained men. The active product was an innovative sustained-release β-alanine microgranules powder blend, administered at high doses (15 g/day) divided into 3 intakes during 30 days. There were 10 participants in the experimental group and 9 in the placebo group, with a mean age of 22.5 ± 3.3 years. Participants were testing at baseline and at the end of study.

Results

In the β-alanine group, there were statistically increases in serum triglycerides, LDL-cholesterol, and urea nitrogen at the end of the study as compared with baseline, although there were no differences with the control group. The occurrence of paresthesia, described above all as tickling, was the majority but presented VAS score less than 3/10 in almost all subjects.

Discussion

More studies are required to evaluate the changes in blood parameters that can be caused by high intake of β-alanine during a long period of time.

Clinical trial registration

ClinicalTrials.gov, identifier (NCT05334121).

Extensive profiling of histidine-containing dipeptides reveals species- and tissue-specific distribution and metabolism in mice, rats, and humans

AIM

Histidine-containing dipeptides (HCDs) are pleiotropic homeostatic molecules with potent antioxidative and carbonyl quenching properties linked to various inflammatory, metabolic, and neurological diseases, as well as exercise performance. However, the distribution and metabolism of HCDs across tissues and species are still unclear.

METHODS

Using a sensitive UHPLC-MS/MS approach and an optimized quantification method, we performed a systematic and extensive profiling of HCDs in the mouse, rat, and human body (in n = 26, n = 25, and n = 19 tissues, respectively).

RESULTS

Our data show that tissue HCD levels are uniquely produced by carnosine synthase (CARNS1), an enzyme that was preferentially expressed by fast-twitch skeletal muscle fibres and brain oligodendrocytes. Cardiac HCD levels are remarkably low compared to other excitable tissues. Carnosine is unstable in human plasma, but is preferentially transported within red blood cells in humans but not rodents. The low abundant carnosine analogue N-acetylcarnosine is the most stable plasma HCD, and is enriched in human skeletal muscles. Here, N-acetylcarnosine is continuously secreted into the circulation, which is further induced by acute exercise in a myokine-like fashion.

CONCLUSION

Collectively, we provide a novel basis to unravel tissue-specific, paracrine, and endocrine roles of HCDs in human health and disease.

The Impact of Pigment-Epithelium-Derived Factor on MCF-7 Cell Metabolism in the Context of Glycaemic Condition

Studies have demonstrated that pigment-epithelium-derived factor (PEDF) is a robust inhibitor of tumour growth and development, implying that this may serve as a promising target for therapeutic intervention. However, the precise impact of PEDF on cancerous cell metabolic pathways remains uncertain despite ongoing research. In this light, this study aimed to employ a metabolomics approach for understanding the metabolic reprogramming events in breast cancer across different glycaemic loads and their response to PEDF. Gas chromatography-quadrupole mass spectrometry (GC/Q-MS) analysis revealed metabolic alterations in ER+ human cell line MCF-7 cells treated with PEDF under varying glycaemic conditions. The identification of significantly altered metabolites was accomplished through MetaboAnalyst (v.5.0) and R packages, which enabled both multivariate and univariate analyses. Out of the 48 metabolites identified, 14 were chosen based on their significant alterations in MCF-7 cells under different glycaemic conditions and PEDF treatment (p < 0.05, VIP > 0.8). Dysregulation in pathways associated with amino acid metabolism, intermediates of the TCA cycle, nucleotide metabolism, and lipid metabolism were detected, and they exhibited different responses to PEDF. Our results suggest that PEDF has a diverse influence on the metabolism of MCF-7 cells in both normo- and hyperglycaemic environments, thereby warranting studies using patient samples to correlate our findings with clinical response in the future.

Acute balenine supplementation in humans as a natural carnosinase-resistant alternative to carnosine

Balenine possesses some of carnosine's and anserine's functions, yet it appears more resistant to the hydrolysing CN1 enzyme. The aim of this study was to elucidate the stability of balenine in the systemic circulation and its bioavailability in humans following acute supplementation. Two experiments were conducted in which (in vitro) carnosine, anserine and balenine were added to plasma to compare degradation profiles and (in vivo) three increasing doses (1-4-10 mg/kg) of balenine were acutely administered to 6 human volunteers. Half-life of balenine (34.9 ± 14.6 min) was respectively 29.1 and 16.3 times longer than that of carnosine (1.20 ± 0.36 min, p = 0.0044) and anserine (2.14 ± 0.58 min, p = 0.0044). In vivo, 10 mg/kg of balenine elicited a peak plasma concentration (Cmax) of 28 µM, which was 4 and 18 times higher than with 4 (p = 0.0034) and 1 mg/kg (p = 0.0017), respectively. CN1 activity showed strong negative correlations with half-life (ρ = - 0.829; p = 0.0583), Cmax (r = - 0.938; p = 0.0372) and incremental area under the curve (r = - 0.825; p = 0.0433). Overall, balenine seems more resistant to CN1 hydrolysis resulting in better in vivo bioavailability, yet its degradation remains dependent on enzyme activity. Although a similar functionality as carnosine and anserine remains to be demonstrated, opportunities arise for balenine as nutraceutical or ergogenic aid.

Exercise training impacts skeletal muscle remodelling induced by metabolic syndrome in ZSF1 rats through metabolism regulation

Metabolic syndrome (MetS), characterized by a set of conditions that include obesity, hypertension, and dyslipidemia, is associated with increased cardiovascular risk. Exercise training (EX) has been reported to improve MetS management, although the underlying metabolic adaptations that drive its benefits remain poorly understood. This work aims to characterize the molecular changes induced by EX in skeletal muscle in MetS, focusing on gastrocnemius metabolic remodelling. ¹H NMR metabolomics and molecular assays were employed to assess the metabolic profile of skeletal muscle tissue from lean male ZSF1 rats (CTL), obese sedentary male ZSF1 rats (MetS-SED), and obese male ZF1 rats submitted to 4 weeks of treadmill EX (5 days/week, 60 min/day, 15 m/min) (MetS-EX). EX did not counteract the significant increase of body weight and circulating lipid profile, but had an anti-inflammatory effect and improved exercise capacity. The decreased gastrocnemius mass observed in MetS was paralleled with glycogen degradation into small glucose oligosaccharides, with the release of glucose-1-phosphate, and an increase in glucose-6-phosphate and glucose levels. Moreover, sedentary MetS animals' muscle exhibited lower AMPK expression levels and higher amino acids' metabolism such as glutamine and glutamate, compared to lean animals. In contrast, the EX group showed changes suggesting an increase in fatty acid oxidation and oxidative phosphorylation. Additionally, EX mitigated MetS-induced fiber atrophy and fibrosis in the gastrocnemius muscle. EX had a positive effect on gastrocnemius metabolism by enhancing oxidative metabolism and, consequently, reducing susceptibility to fatigue. These findings reinforce the importance of prescribing EX programs to patients with MetS.

Molecular Profiling of Athletes Performing High-Intensity Exercises in Extreme Environments

The aim of this study was to determine the influence of high-intensity training under extreme conditions (T = 40 °C) on the metabolism and immunological reactions of athletes. Male triathletes (n = 11) with a high level of sports training performed load testing to failure (17 ± 2.7 min) and maximum oxygen consumption (64.1 ± 6.4 mL/min/kg). Blood plasma samples were collected before and immediately after exercise. Mass spectrometric metabolomic analysis identified 30 metabolites and 6 hormones in the plasma, of which 21 and 4 changed after exercise, respectively. Changes in the intermediate products of tricarboxylic and amino acids were observed (FC > 1.5) after exercise. The obtained data can be associated with the effect of physical activity on metabolism in athletes. Therefore, constant monitoring of the biochemical parameters of athletes can help coaches identify individual shortcomings in a timely manner and track changes, especially as the volume of training increases. In addition, it was revealed that the immunological reaction (manifestation of a hyperactive reaction to food components) is personalized in nature. Therefore, it is important for coaches and sports doctors to analyze and control the eating behavior of athletes to identify food intolerances or food allergies in a timely manner and develop an individual elimination diet.

Oral administration of live combined Bacillus subtilis and Enterococcus faecium alleviates colonic oxidative stress and inflammation in osteoarthritic rats by improving fecal microbiome metabolism and enhancing the colonic barrier

Osteoarthritis (OA) causes intestinal damage. The protective effect of probiotics on the intestine is indeed effective; however, the mechanism of protection against intestinal damage in OA is not clear. In this study, we used meniscal/ligamentous injury (MLI) to mimic OA in rats and explored the colonic protective effects of Bacillus subtilis and Enterococcus faecium on OA. Our study showed that treatment with B. subtilis and E. faecium attenuated colonic injury and reduced inflammatory and oxidative stress factors in the serum of osteoarthritic rats. α- and ß diversity of the fecal flora were not different among groups; no significant differences were observed in the abundances of taxa at the phylum and genus levels. We observed the presence of the depression-related genera Alistipes and Paraprevotella. Analysis of fecal untargeted metabolism revealed that histamine level was significantly reduced in the colon of OA rats, affecting intestinal function. Compared to that in the control group, the enriched metabolic pathways in the OA group were primarily for energy metabolisms, such as pantothenate and CoA biosynthesis, and beta-alanine metabolism. The treatment group had enriched linoleic acid metabolism, fatty acid biosynthesis, and primary bile acid biosynthesis, which were different from those in the control group. The differences in the metabolic pathways between the treatment and OA groups were more evident, primarily in symptom-related metabolic pathways such as Huntington's disease, spinocerebellar ataxia, energy-related central carbon metabolism in cancer, pantothenate and CoA biosynthesis metabolic pathways, as well as some neurotransmission and amino acid transport, and uptake- and synthesis-related metabolic pathways. On further investigation, we found that B. subtilis and E. faecium treatment enhanced the colonic barrier of OA rats, with elevated expressions of tight junction proteins occludin and Zonula occludens 1 and MUC2 mRNA. Intestinal permeability was reduced, and serum LPS levels were downregulated in the treatment group. B. subtilis and E. faecium also regulated the oxidative stress pathway Keap1/Nrf2, promoted the expression of the downstream protective proteins HO-1 and Gpx4, and reduced intestinal apoptosis. Hence, B. subtilis and E. faecium alleviate colonic oxidative stress and inflammation in OA rats by improving fecal metabolism and enhancing the colonic barrier.

Role of gut microbe-derived metabolites in cardiometabolic diseases: Systems based approach

BACKGROUND

The gut microbiome influences host physiology and cardiometabolic diseases by interacting directly with intestinal cells or by producing molecules that enter the host circulation. Given the large number of microbial species present in the gut and the numerous factors that influence gut bacterial composition, it has been challenging to understand the underlying biological mechanisms that modulate risk of cardiometabolic disease.

SCOPE OF THE REVIEW

Here we discuss a systems-based approach that involves simultaneously examining individuals in populations for gut microbiome composition, molecular traits using "omics" technologies, such as circulating metabolites quantified by mass spectrometry, and clinical traits. We summarize findings from landmark studies using this approach and discuss future applications.

MAJOR CONCLUSIONS

Population-based integrative approaches have identified a large number of microbe-derived or microbe-modified metabolites that are associated with cardiometabolic traits. The knowledge gained from these studies provide new opportunities for understanding the mechanisms involved in gut microbiome-host interactions and may have potentially important implications for developing novel therapeutic approaches.

Carnosine as a potential therapeutic for the management of peripheral vascular disease

AIMS

To evaluate the potential role of carnosine in the management of peripheral vascular disease.

DATA SYNTHESIS

Peripheral vascular disease is growing in its burden and impact; however it is currently under researched, and there are a lack of strong, non-invasive therapeutic options for the clinicians. Carnosine is a dipeptide stored particularly in muscle and brain tissue, which exhibits a wide range of physiological activities, which may be beneficial as an adjunct treatment for peripheral vascular disease. Carnosine's strong anti-inflammatory, antioxidant and antiglycating actions may aid in the prevention of plaque formation, through protective actions on the vascular endothelium, and the inhibition of foam cells. Carnosine may also improve angiogenesis, exercise performance and vasodilatory response, while protecting from ischemic tissue injury.

CONCLUSIONS

Carnosine may have a role as an adjunct treatment for peripheral vascular disease alongside typical exercise and surgical interventions, and may be used in high risk individuals to aid in the prevention of atherogenesis.

CLINICAL RECOMMENDATION

This review identifies a beneficial role for carnosine supplementation in the management of patients with peripheral vascular disease, in conjunction with exercise and revascularization. Carnosine as a supplement is safe, and associated with a host of beneficial effects in peripheral vascular disease and its key risk factors.

NMR-Based Metabolomic Analysis for the Effects of Trimethylamine N-Oxide Treatment on C2C12 Myoblasts under Oxidative Stress

The gut microbial metabolite trimethylamine N-oxide (TMAO) has received increased attention due to its close relationship with cardiovascular disease and type 2 diabetes. In previous studies, TMAO has shown both harmful and beneficial effects on various tissues, but the underlying molecular mechanisms remain to be clarified. Here, we explored the effects of TMAO treatment on H₂O₂-impaired C2C12 myoblasts, analyzed metabolic changes and identified significantly altered metabolic pathways through nuclear magnetic resonance-based (NMR-based) metabolomic profiling. The results exhibit that TMAO treatment partly alleviated the H₂O₂-induced oxidative stress damage of cells and protected C2C12 myoblasts by improving cell viability, increasing cellular total superoxide dismutase capacity, improving the protein expression of catalase, and reducing the level of malondialdehyde. We further showed that H₂O₂ treatment decreased levels of branched-chain amino acids (isoleucine, leucine and valine) and several amino acids including alanine, glycine, threonine, phenylalanine and histidine, and increased the level of phosphocholine related to cell membrane structure, while the TMAO treatment partially reversed the changing trends of these metabolite levels by improving the integrity of the cell membranes. This study indicates that the TMAO treatment may be a promising strategy to alleviate oxidative stress damage in skeletal muscle.

Skeletal muscle oxidative stress and inflammation in aging: Focus on antioxidant and anti-inflammatory therapy

With aging, the progressive loss of skeletal muscle will have negative effect on multiple physiological parameters, such as exercise, respiration, thermoregulation, and metabolic homeostasis. Accumulating evidence reveals that oxidative stress and inflammation are the main pathological characteristics of skeletal muscle during aging. Here, we focus on aging-related sarcopenia, summarize the relationship between aging and sarcopenia, and elaborate on aging-mediated oxidative stress and oxidative damage in skeletal muscle and its critical role in the occurrence and development of sarcopenia. In addition, we discuss the production of excessive reactive oxygen species in aging skeletal muscle, which reduces the ability of skeletal muscle satellite cells to participate in muscle regeneration, and analyze the potential molecular mechanism of ROS-mediated mitochondrial dysfunction in aging skeletal muscle. Furthermore, we have also paid extensive attention to the possibility and potential regulatory pathways of skeletal muscle aging and oxidative stress mediate inflammation. Finally, in response to the abnormal activity of oxidative stress and inflammation during aging, we summarize several potential antioxidant and anti-inflammatory strategies for the treatment of sarcopenia, which may provide beneficial help for improving sarcopenia during aging.

Integrated metabolomics revealed the fibromyalgia-alleviation effect of Mo2C nanozyme through regulated homeostasis of oxidative stress and energy metabolism

Fibromyalgia (FM), the most common cause of chronic musculoskeletal pain in the general public, lacks advanced therapeutic methodology and detailed bioinformation. However, acting as a newly developed and important transition metal carbide or carbonitride, the Mo2C nanozyme has provided a novel iatrotechnique with excellent bioactivity in a cell/animal model, which also exhibits potential prospects for future clinical applications. In addition, high-content and high-throughput integrated metabolomics (including aqueous metabolomics, lipidomics, and desorption electrospray ionization-mass spectrometry imaging) also specializes in qualitative and quantitative analysis of metabolic shifts at the molecular level. In this work, the FM-alleviation effect of Mo2C nanozyme was investigated through integrated metabolomics in a mouse model. An advanced platform combining gas chromatography-mass spectrometry, liquid chromatography-mass spectrometry and bioinformatics was utilized to study the variation in the mouse metabolome and lipidome. The results revealed that Mo2C treatment could effectively enhance energy metabolism-related biological events impaired by FM, leading to homeostasis of oxidative stress and energy metabolism toward the control levels. During this process, Mo2C facilitated the elimination of ROS in plasma and cells and the rehabilitation of mice from oxidative stress and mitochondrial dysfunction. It was believed that such an integrated metabolomics study on the FM-alleviation effect of Mo2C nanozyme could provide another excellent alternative to traditional Mo2C-based research with numerous pieces of bioinformation, further supporting research area innovation, material modification, and clinical application.

The ergogenic effect of acute carnosine and anserine supplementation: dosing, timing, and underlying mechanism

Background

Recent studies suggest that acute-combined carnosine and anserine supplementation has the potential to improve the performance of certain cycling protocols. Yet, data on optimal dose, timing of ingestion, effective exercise range, and mode of action are lacking. Three studies were conducted to establish dosing and timing guidelines concerning carnosine and anserine intake and to unravel the mechanism underlying the ergogenic effects.

Methods

First, a dose response study A was conducted in which 11 men randomly received placebo, 10, 20, or 30 mg.kg⁻¹ of both carnosine and anserine. They performed 3x maximal voluntary isometric contractions (MVC), followed by a 5 x 6 s repeated cycling sprint ability test (RSA), once before the supplement and 30 and 60 minutes after. In a second study, 15 men performed 3x MVCs with femoral nerve electrical stimulation, followed by an RSA test, once before 30 mg.kg⁻¹ carnosine and anserine and 60 minutes after. Finally, in study C, eight men performed a high intensity cycling training after randomly ingesting 30 mg.kg⁻¹ of carnosine and anserine, a placebo or antihistamines (reduce post-exercise blood flow) to investigate effects on muscle perfusion.

Results

Study A showed a 3% peak power (p = 0.0005; 95% CI = 0.07 to 0.27; ES = 0.91) and 4.5% peak torque (p = 0.0006; 95% CI = 0.12 to 0.50; ES = 0.87) improvement on RSA and MVC, with 30 mg.kg⁻¹ carnosine + anserine ingestion 60 minutes before the performance yielding the best results. Study B found no performance improvement on group level; however, a negative correlation (r = −0.54; p = 0.0053; 95% CI = −0.77 to −0.19) was found between carnosinase enzyme activity (responsible for carnosine and anserine breakdown) and performance improvement. No effect of the supplement on neuromuscular function nor on muscle perfusion was found.

Conclusions

These studies reveal that acute ingestion of 30 mg.kg⁻¹ of both carnosine and anserine, 60 minutes before a high intensity exercise, can potentially improve performance, such as short cycling sprints or maximal muscle contractions. Subjects with lower carnosinase activity, and thus a slower breakdown of circulating dipeptides, appear to benefit more from this ergogenic effect. Finally, neither the involvement of a direct effect on neuromuscular function, nor an indirect effect on recovery through increased muscle perfusion could be confirmed as potential mechanism of action. The ergogenic mechanism therefore remains elusive.

Pathway-based metabolomics study of sarcopenia-related traits in two US cohorts

We aimed to validate two metabolites, aspartic acid and glutamic acid, which were associated with sarcopenia-related traits, muscle mass and strength, in our previous untargeted metabolomics study and to identify novel metabolites from five metabolic pathways involving these two metabolites. We included a discovery cohort of 136 white women aged 20-40 years (used for the previous untargeted metabolomics analysis) and a validation cohort of 174 subjects aged ≥ 60 years, including men and women of white and black. A targeted LC-MS assay successfully detected 12 important metabolites from these pathways. Aspartic acid was associated with muscle mass and strength in the discovery cohort, but not in the validation cohort. However, glutamic acid was associated with these sarcopenia traits in both cohorts. Additionally, N-acetyl-L-aspartic acid and carnosine were the newly identified metabolites that were associated with muscle strength in the discovery and validation cohorts, respectively. We did not observe any significant sex and race differences in the associations of these metabolites with sarcopenia traits in the validation cohort. Our findings indicated that glutamic acid might be consistently associated with sarcopenia-related traits across age, sex, and race. They also suggested that age-specific metabolites and metabolic pathways might be involved in muscle regulation.

Motor Unit Fatigability following Chronic Carnosine Supplementation in Aged Rats

Studies suggest that carnosine (beta-alanyl-L-histidine) is effective in treating neuromuscular diseases associated with aging, but there is still a need to clarify its role in motor units (MUs) function during aging. In this study, 40 male Wistar rats aged 15 months were randomly assigned to a control or to two experimental groups in which 0.1% carnosine supplementation was performed for 10 or 34 weeks. After 34 weeks, we examined fast fatigable (FF), fast fatigue-resistant (FR) and slow (S) MUs’ force properties and fatigability, as well as antioxidant potential, advanced glycation end products, activity of enzymes, and histidyl dipeptides content in the medial gastrocnemius muscle. Short- and long-term carnosine supplementation maintained the force of FF MUs at a higher level during its rapid decline seen from the initial 10 to 70 s of the fatigue test. In FF, especially long-term, and in FR MUs, especially short-term, carnosine supplementation resulted in less rapid force decline during the initial 70 s of the second fatigue protocol. Carnosine supplementation did not change muscle antioxidant potential and mortality rate (~35% in all groups), nor muscle mass with aging. Moreover, instead of the expected increase, a decrease in histidyl dipeptides by ~30% in the red portion of medial gastrocnemius muscle after long-term supplementation was found. After chronic carnosine supplementation, the specific changes in fatigue resistance were observed in FF and FR units, but not in S MU types that were not accompanied by an improvement of antioxidant potential and activity of glycolytic or oxidative enzymes in aged rats. These observations indicate that carnosine supplementation during aging may generate different physiological adaptations which should be considered as an important factor when planning treatment strategies.

Unravelling Mechanisms of Doxorubicin-Induced Toxicity in 3D Human Intestinal Organoids

Doxorubicin is widely used in the treatment of different cancers, and its side effects can be severe in many tissues, including the intestines. Symptoms such as diarrhoea and abdominal pain caused by intestinal inflammation lead to the interruption of chemotherapy. Nevertheless, the molecular mechanisms associated with doxorubicin intestinal toxicity have been poorly explored. This study aims to investigate such mechanisms by exposing 3D small intestine and colon organoids to doxorubicin and to evaluate transcriptomic responses in relation to viability and apoptosis as physiological endpoints. The in vitro concentrations and dosing regimens of doxorubicin were selected based on physiologically based pharmacokinetic model simulations of treatment regimens recommended for cancer patients. Cytotoxicity and cell morphology were evaluated as well as gene expression and biological pathways affected by doxorubicin. In both types of organoids, cell cycle, the p53 signalling pathway, and oxidative stress were the most affected pathways. However, significant differences between colon and SI organoids were evident, particularly in essential metabolic pathways. Short time-series expression miner was used to further explore temporal changes in gene profiles, which identified distinct tissue responses. Finally, in silico proteomics revealed important proteins involved in doxorubicin metabolism and cellular processes that were in line with the transcriptomic responses, including cell cycle and senescence, transport of molecules, and mitochondria impairment. This study provides new insight into doxorubicin-induced effects on the gene expression levels in the intestines. Currently, we are exploring the potential use of these data in establishing quantitative systems toxicology models for the prediction of drug-induced gastrointestinal toxicity.

Effects of Animal Welfare-Certified Rearing Systems on the Blood Parameters and Meat Quality Characteristics of Broilers at the Farm Level in Korea

Compared to the conventional farms (CF) rearing of broilers, the rearing management of animal welfare-certified farms (AF) must provide low stocking density, perch, air regulation, and feeding plant-based protein. This study aimed to compare the effects of rearing management in CF and AF on blood parameters, meat quality, and bioactive compound content in Ross 308 broiler chickens at the farm level before transportation to slaughterhouses. Blood and meat samples were obtained at 28-35-day-old chickens from three CF and three AF. In blood samples, low-density lipoprotein cholesterol (p<0.05), triglyceride (p<0.001), glucose (p<0.01), total protein (p<0.001), albumin (p<0.01), and white blood cell (p<0.001) levels as well as the heterophil/ lymphocyte ratio [stress index (SI), p<0.001] were lower in broilers from AF than in CF. In meat samples, shear force (p<0.001, p<0.05), and carnosine contents (p<0.001, p<0.05) in both breast and thigh meat from AF were higher than those in meat from CF. The contents of linoleic acid (p<0.001), α-linolenic acid (p<0.001), and eicosapentaenoic acid (p<0.05) were higher in the samples from AF than those from CF. This study reveals that such differences are influenced by the different rearing factors in nutrition, housing, and management practices between CF and AF. Supplementation of plant-based protein and enough space to move due to lower stocking density accounts for the large differences between them. These results can be used as preliminary data showing that the AF system reduces the SI and enhances carnosine and polyunsaturated fatty acids levels in chicken meat at the farm level before transportation.

Endogenous dipeptide-carnosine supplementation ameliorates hypobaric hypoxia-induced skeletal muscle loss via attenuating endoplasmic reticulum stress response and maintaining proteostasis

High altitude is an environmental stress that is accompanied with numerous adverse biological responses, including skeletal muscle weakness and muscle protein loss. Skeletal muscle wasting is an important clinical problem, progressing to critical illness, associated with increased morbidity and mortality. The present study explores the protective efficacy of endogenous dipeptide, carnosine (CAR), supplementation in ameliorating skeletal muscle protein loss under hypobaric hypoxia (HH). Male Sprague-Dawley rats (n = 5) were randomly divided into control group, HH-exposed group (3 days HH exposure equivalent to 7,620 m), and HH-exposed rats supplemented with carnosine (3 days; 150 mg/kg b.w, orally) (HH + CAR). HH-exposed rats supplemented with CAR ameliorated HH-induced oxidative protein damage, lipid peroxidation, and maintained pro-inflammatory cytokines levels. HH-associated muscle protein degradative pathways, including calpain, ubiquitination, endoplasmic reticulum stress, autophagy, and apoptosis were also regulated in carnosine-supplemented rats. Further, the muscle damage marker, the levels of serum creatine phosphokinase were also reduced in HH + CAR co-supplemented rats which proved the protective efficacy of CAR against hypobaric hypoxia-induced muscle protein loss. Altogether, CAR supplementation ameliorated HH-induced skeletal muscle protein loss via performing multifaceted ways, mainly by maintaining redox homeostasis and proteostasis in skeletal muscle.

Comparative Evaluation of the Antioxidant Properties of Whole Peanut Flour, Defatted Peanut Protein Meal, and Peanut Protein Concentrate

Defatted peanut meal is a low value agro-industrial residue from peanut oil production with potential use as a value addition food ingredient. In this study, peanuts were roasted at 100°C for 5 min, de-skinned and milled into whole peanut flour (WPF) from which the defatted meal (DPM) was prepared by acetone extraction and the peanut protein concentrate (PPC) obtained from the DPM using isoelectric pH precipitation. The protein content, amino acid profile, total phenolic content (TPC), total flavonoid content (TFC) and in vitro antioxidant properties of the peanut samples were then determined. Results showed that DPM had a TPC of 0.12 ± 0.02 mg gallic acid equivalent (GAE)/g, which was significantly (p &lt; 0.05) higher than and twice the levels in WPF and PPC (0.06 ± 0.03 mg GAE/g). However, WPF had TFC of 0.21 ± 0.01 μg quercetin equivalent (QE)/g, which was significantly (p &lt; 0.05) higher than DPM (0.16 ± 0.03 μg QE/g) and PPC (0.11 ± 0.05 μg QE/g). However, PPC had superior amino acid profile in addition to stronger radical scavenging and metal chelation activities than WPF and DPM. The results suggest that PPC is a protein rich product that could be utilized as an ingredient in food product fortification to enhance nutritional quality and in the formulation of functional foods with antioxidant benefits.

Effect of β-alanine and sodium bicarbonate co-supplementation on the body's buffering capacity and sports performance: A systematic review

Muscle acidification is one of the main factors causing fatigue during exercise, thus compromising performance. The sport supplements beta alanine (β-A) and sodium bicarbonate (SB) are thought to enhance the effects of the body's buffer systems by reducing H⁺ concentrations. The aim of this systematic review was to analyze the effects of β-A and SB co-supplementation on the organism's buffering capacity and sport performance. The databases PubMed, Web of Science, Medline, CINAHL and SPORTDiscus were searched until November 2021 following PRISMA guidelines. Randomized controlled trials, at least single-blind, performed in athletes of any age were considered. Nine studies including a total of 221 athletes were identified for review. Athletes were supplemented with β-A and SB while they performed exercise tests to assess physical performance and buffer capacity. Five of the nine studies indicated there was some additional improvement in buffering capacity and performance with co-supplementation, while one study concluded that the effect was comparable to the added effects of the individual supplements. According to the results of the studies reviewed, we would recommend β-A and SB co-supplementation during high intensity exercises lasting between 30 s and 10 min.

Nutritional optimization for female elite football players-topical review

Women's football is an intermittent sport characterized by frequent intense actions throughout the match. The high number of matches with limited recovery time played across a long competitive season underlines the importance of nutritional strategies to meet these large physical demands. In order to maximize sport performance and maintain good health, energy intake must be optimal. However, a considerable proportion of female elite football players does not have sufficient energy intake to match the energy expenditure, resulting in low energy availability that might have detrimental physiologic consequences and impair performance. Carbohydrates appear to be the primary fuel covering the total energy supply during match-play, and female elite football players should aim to consume sufficient carbohydrates to meet the requirements of their training program and to optimize the replenishment of muscle glycogen stores between training bouts and matches. However, several macro- and micronutrients are important for ensuring sufficient energy and nutrients for performance optimization and for overall health status in female elite football players. The inadequacy of macro-and micronutrients in the diet of these athletes may impair performance and training adaptations, and increase the risk of health disorders, compromising the player's professional career. In this topical review, we present knowledge and relevant nutritional recommendations for elite female football players for the benefit of sports nutritionists, dietitians, sports scientists, healthcare specialists, and applied researchers. We focus on dietary intake and cover the most pertinent topics in sports nutrition for the relevant physical demands in female elite football players as follows: energy intake, macronutrient and micronutrient requirements and optimal composition of the everyday diet, nutritional and hydration strategies to optimize performance and recovery, potential ergogenic effects of authorized relevant supplements, and future research considerations.

Carnosine and skeletal muscle dysfunction in a rodent multiple sclerosis model

Muscle weakness and fatigue are primary manifestations of multiple sclerosis (MS), a chronic disease of the central nervous system. Interventions that enhance muscle function may improve overall physical well-being of MS patients. Recently, we described that levels of carnosine, an endogenous muscle dipeptide involved in contractile function and fatigue-resistance, are reduced in muscle tissue from MS patients and a monophasic rodent MS model (experimental autoimmune encephalomyelitis, EAE). In the present study, we aimed to (1) confirm this finding in a chronic EAE model, along with the characterization of structural and functional muscle alterations, and (2) investigate the effect of carnosine supplementation to increase/restore muscle carnosine levels and improve muscle function in EAE. We performed muscle immunohistochemistry and ex vivo contractility measurements to examine muscle structure and function at different stages of EAE, and following nutritional intervention (oral carnosine: 3, 15 or 30 g/L in drinking water). Immunohistochemistry revealed progressively worsening muscle fiber atrophy and a switch towards a fast-twitch muscle phenotype during EAE. Using ex vivo muscle contractility experiments, we observed reductions in muscle strength and contraction speed, but no changes in muscle fatigability of EAE mice. However, carnosine levels were unaltered during all stages of EAE, and even though oral carnosine supplementation dose-dependently increased muscle carnosine levels up to + 94% after 56 days EAE, this did not improve muscle function of EAE mice. In conclusion, EAE mice display significant, yet time-dependent, muscular alterations, and carnosine intervention does not improve muscle function in EAE.

Diet and redox state in maintaining skeletal muscle health and performance at high altitude

High altitude exposure leads to compromised physical performance with considerable weight loss. The major stressor at high altitude is hypobaric hypoxia which leads to disturbance in redox homeostasis. Oxidative stress is a well-known trigger for many high altitude illnesses and regulates several key signaling pathways under stressful conditions. Altered redox homeostasis is considered the prime culprit of high altitude linked skeletal muscle atrophy. Hypobaric hypoxia disturbs redox homeostasis through increased RONS production and compromised antioxidant system. Increased RONS disturbs the cellular homeostasis via multiple ways such as inflammation generation, altered protein anabolic pathways, redox remodeling of RyR1 that contributed to dysregulated calcium homeostasis, enhanced protein degradation pathways via activation calcium-regulated protein, calpain, and apoptosis. Ultimately, all the cellular signaling pathways aggregately result in skeletal muscle atrophy. Dietary supplementation of phytochemicals could become a safe and effective intervention to ameliorate skeletal muscle atrophy and enhance the physical performance of the personnel who are staying at high altitude regions. The present evidence-based review explores few dietary supplementations which regulate several signaling mechanisms and ameliorate hypobaric hypoxia induced muscle atrophy and enhances physical performance. However, a clinical research trial is required to establish proof-of-concept.

Effects of dietary inclusion of yerba mate (Ilex paraguariensis) extract on lamb muscle metabolomics and physicochemical properties in meat

This study aimed to evaluate the effect of dietary yerba mate (Ilex paraguariensis) extract (YME) on muscle metabolomics and physicochemical properties of lamb meat. Thirty-six uncastrated male lambs (90 d old) were fed experimental diets, which treatments consisted of 0%, 1%, 2%, and 4% inclusion of YME. Animals were fed for 50 d before slaughter. Muscle and meat samples were collected for metabolomics and meat quality analysis, respectively. The experiment was carried out in a randomized block design and analyzed using orthogonal contrasts. There was a quadratic effect of YME inclusion in tenderness (P < 0.05) and a positive linear effect on meat lightness (P < 0.05). No qualitative changes (P > 0.05) on individual metabolites were observed; however, changes in the quantitative metabolic profile were observed, showing that animals fed 1% and 2% of YME have a greater concentration of desirable endogenous muscle antioxidants, with direct impact on metabolic pathways related to beta-alanine metabolism and glutathione metabolism. Therefore, YME dietary supplementation up to 2% of the diet to lambs had little to no effects on the majority of meat quality traits evaluated; moreover, 4% of YME inclusion negatively affected feed intake and meat quality traits.

Role of Nrf2 in Synaptic Plasticity and Memory in Alzheimer's Disease

Nuclear factor erythroid 2-related factor 2 (Nrf2) is an important transcription factor that reduces oxidative stress. When reactive oxygen species (ROS) or reactive nitrogen species (RNS) are detected, Nrf2 translocates from the cytoplasm into the nucleus and binds to the antioxidant response element (ARE), which regulates the expression of antioxidant and anti-inflammatory genes. Nrf2 impairments are observed in the majority of neurodegenerative disorders, including Alzheimer’s disease (AD). The classic hallmarks of AD include β-amyloid (Aβ) plaques, and neurofibrillary tangles (NFTs). Oxidative stress is observed early in AD and is a novel therapeutic target for the treatment of AD. The nuclear translocation of Nrf2 is impaired in AD compared to controls. Increased oxidative stress is associated with impaired memory and synaptic plasticity. The administration of Nrf2 activators reverses memory and synaptic plasticity impairments in rodent models of AD. Therefore, Nrf2 activators are a potential novel therapeutic for neurodegenerative disorders including AD.

Carnosine, Small but Mighty-Prospect of Use as Functional Ingredient for Functional Food Formulation

Carnosine is a dipeptide synthesized in the body from β-alanine and L-histidine. It is found in high concentrations in the brain, muscle, and gastrointestinal tissues of humans and is present in all vertebrates. Carnosine has a number of beneficial antioxidant properties. For example, carnosine scavenges reactive oxygen species (ROS) as well as alpha-beta unsaturated aldehydes created by peroxidation of fatty acid cell membranes during oxidative stress. Carnosine can oppose glycation, and it can chelate divalent metal ions. Carnosine alleviates diabetic nephropathy by protecting podocyte and mesangial cells, and can slow down aging. Its component, the amino acid beta-alanine, is particularly interesting as a dietary supplement for athletes because it increases muscle carnosine, and improves effectiveness of exercise and stimulation and contraction in muscles. Carnosine is widely used among athletes in the form of supplements, but rarely in the population of cardiovascular or diabetic patients. Much less is known, if any, about its potential use in enriched food. In the present review, we aimed to provide recent knowledge on carnosine properties and distribution, its metabolism (synthesis and degradation), and analytical methods for carnosine determination, since one of the difficulties is the measurement of carnosine concentration in human samples. Furthermore, the potential mechanisms of carnosine's biological effects in musculature, metabolism and on immunomodulation are discussed. Finally, this review provides a section on carnosine supplementation in the form of functional food and potential health benefits and up to the present, neglected clinical use of carnosine.

Isolation of balenine from opah (Lampris megalopsis) muscle and comparison of antioxidant and iron-chelating activities with other major imidazole dipeptides

Balenine (Bal) in opah muscle was extracted using hot water and purified by ion-exchange chromatography and recrystallization to provide 41 g of over 95% pure Bal from 1 kg of opah muscle. The structure of purified Bal was identical to that of an authentic Bal standard by NMR analysis. The antioxidant (ORAC and HORAC values) and Fe(II) ion-chelating abilities of purified Bal were examined by comparison with two major imidazole dipeptides, carnosine (Car) and anserine (Ans). Opah-derived Bal showed significantly higher ORAC and HORAC values and Fe(II) ion-chelating ability at 0.3 mM. In silico molecular simulation revealed that Bal and Car formed hydrogen bonds between the hydrogen atom of the imidazole imino group and the carboxyl carbonyl oxygen, whereas Ans did not. The proposed method for extracting and purifying Bal from opah muscle suggests that opah can be utilized as a functional food or Bal resource.

Untargeted Metabolomic Characteristics of Skeletal Muscle Dysfunction in Rabbits Induced by a High Fat Diet

Simple Summary

In the present study, we performed an untargeted metabolomic analysis of skeletal muscle of rabbits and found that the skeletal muscle of rabbits fed a high-fat diet is rich in many metabolites, most of which are associated with type 2 diabetes and metabolic syndrome. In this paper, the mechanism of action of these metabolites in skeletal muscle and the metabolic pathways that interfere with the normal operation mechanism of the body are described and presented in the form of charts. Finally, we found that skeletal muscle-rich phospholipids, long-chain carnitine, histidine, carnosine, and tetrahydrocortisone may be potential markers for type 2 diabetes and metabolic syndrome, and may serve as potential therapeutic targets for related diseases in the future.

Abstract

Type 2 diabetes and metabolic syndrome caused by a high fat diet (HFD) have become public health problems worldwide. These diseases are characterized by the oxidation of skeletal muscle mitochondria and disruption of insulin resistance, but the mechanisms are not well understood. Therefore, this study aims to reveal how high-fat diet causes skeletal muscle metabolic disorders. In total, 16 weaned rabbits were randomly divided into two groups, one group was fed a standard normal diet (SND) and the other group was fed a high fat diet (HFD) for 5 weeks. At the end of the five-week experiment, skeletal muscle tissue samples were taken from each rabbit. Untargeted metabolomic analysis was performed using ultra-performance liquid chromatography combined with mass spectrometry (UHPLC-MS/MS). The results showed that high fat diet significantly altered the expression levels of phospholipids, LCACs, histidine, carnosine, and tetrahydrocorticosterone in skeletal muscle. Principal component analysis (PCA) and least squares discriminant analysis (PLS-DA) showed that, compared with the SND group, skeletal muscle metabolism in HFD group was significantly up-regulated. Among 43 skeletal muscle metabolites in the HFD group, phospholipids, LCACs, histidine, carnosine, and tetrahydrocorticosteroids were identified as biomarkers of skeletal muscle metabolic diseases, and may become potential physiological targets of related diseases in the future. Untargeted metabonomics analysis showed that high-fat diet altered the metabolism of phospholipids, carnitine, amino acids and steroids in skeletal muscle of rabbits. Notably, phospholipids, LCACs, histidine, carnopeptide, and tetrahydrocorticosteroids block the oxidative capacity of mitochondria and disrupt the oxidative capacity of glucose and the fatty acid-glucose cycle in rabbit skeletal muscle.

Taurine Protects C2C12 Myoblasts From Impaired Cell Proliferation and Myotube Differentiation Under Cisplatin-Induced ROS Exposure

In cancer patients, chemotherapeutic medication induces aberrant ROS (reactive oxygen species) accumulation in skeletal muscles, resulting in myofiber degradation, muscle weakness, and even cachexia, which further leads to poor therapeutic outcomes. Acting as an antioxidant, taurine is extensively used to accelerate postexercise muscle recovery in athletes. The antioxidant effects of taurine have been shown in mature myotubes and myofibers but not yet in myoblasts, the myotube precursor. The proliferation and differentiation ability of myoblasts play a very important role in myofiber repair and regeneration, which is usually impaired during chemotherapeutics in cancer patients as well. Here, we explored the effects of taurine supplementation on C2C12 myoblasts exposed to cisplatin-induced ROS. We found that cisplatin treatment led to dramatically decreased cell viability; accumulated ROS level; down-regulated expressions of MyoD1 (myoblast determination protein 1), myogenin, and MHC (myosin heavy chain); and impaired myotube differentiation in myoblasts. Significantly, taurine supplementation protected myoblasts against cisplatin-induced cell viability decrease, promoted cellular ROS clearance, and, most importantly, preserved the expressions of MyoD1, myogenin, and MHC as well as myotube differentiation ability. We further conducted NMR-based metabolomic analysis to clarify the underlying molecular mechanisms. We identified 14 characteristic metabolites primarily responsible for the discrimination of metabolic profiles between cisplatin-treated cells and normal counterparts, including increased levels of BCAAs (branched-chain amino acids: leucine and isoleucine), alanine, glycine, threonine, glucose, ADP (adenosine diphosphate), phenylalanine, and PC (O-phosphocholine), and decreased levels of lysine, β-alanine, choline, GPC (sn-glycero-3-phosphocholine), and myo-inositol. Evidently, taurine supplementation partially reversed the changing trends of several metabolites (isoleucine, threonine, glycine, PC, β-alanine, lysine, and myo-inositol). Furthermore, taurine supplementation promoted the proliferation and myotube differentiation of myoblasts by alleviating cellular catabolism, facilitating GSH (reduced glutathione) biosynthesis, improving glucose utilization and TCA (tricarboxylic acid) cycle anaplerosis, and stabilizing cellular membranes. Our results demonstrated the protective effects of taurine on cisplatin-impaired myoblasts and elucidated the mechanistic rationale for the use of taurine to ameliorate muscle toxicity in clinical chemotherapy cancer patients.

Beta-Alanine Supplementation and Sport Climbing Performance

BACKGROUND

Supplementing β-alanine (BA) improves exercise performance in efforts that are highly dependent on anaerobic glycolysis. As it has not yet been established whether it relates to climbing, the current study aimed to investigate the effects of BA on climbing-specific performance.

METHODS

Fifteen elite climbers performed intermittent high-force high-velocity campus board exercise, and two bouldering traverses, hard and easy. They ingested 4.0 g·d^-1 BA or placebo for four weeks in a double-blind, pre/post experimental design.

RESULTS

In the campus board trial, ANOVA revealed a tendency toward significance (p = 0.066). Post hoc analysis revealed that there was a significant (p = 0.002) and "large" (d = 1.55) increase in the total number of "slaps" in the BA group. No significant supplementation × group interaction was found in "hard" traverse and a significant interaction for mean changes in number of moves (p = 0.025) and in time to failure (p = 0.044) on an "easy" traverse. Post hoc analysis revealed that only the BA group significantly improved from baseline in number of moves (+9.5) and time to failure (+32 s). Effect sizes were d = 1.73 and d = 1.44, respectively.

CONCLUSIONS

Four weeks of BA supplementation can improve performance during continuous climbing lasting about 1 min and repeated bouts of upper body campus-like movements. However, it failed to enhance climbing of a shorter duration.

CORP: quantification of human skeletal muscle carnosine concentration by proton magnetic resonance spectroscopy

Noninvasive techniques to quantify metabolites in skeletal muscle provide unique insight into human physiology and enable the translation of research into practice. Proton magnetic resonance spectroscopy (¹H-MRS) permits the assessment of several abundant muscle metabolites in vivo, including carnosine, a dipeptide composed of the amino acids histidine and beta-alanine. Muscle carnosine loading, accomplished by chronic oral beta-alanine supplementation, improves muscle function and exercise capacity and has pathophysiological relevance in multiple diseases. Moreover, the marked difference in carnosine content between fast-twitch and slow-twitch muscle fibers has rendered carnosine an attractive candidate to estimate human muscle fiber type composition. However, the quantification of carnosine with ¹H-MRS requires technical expertise to obtain accurate and reproducible data. In this review, we describe the technical and physiological factors that impact the detection, analysis, and quantification of carnosine in muscle with ¹H-MRS. We discuss potential sources of error during the acquisition and preprocessing of the ¹H-MRS spectra and present best practices to enable the accurate, reliable, and reproducible application of this technique.

Proton magnetic resonance spectroscopy in skeletal muscle: Experts' consensus recommendations

1 H-MR spectroscopy of skeletal muscle provides insight into metabolism that is not available noninvasively by other methods. The recommendations given in this article are intended to guide those who have basic experience in general MRS to the special application of 1 H-MRS in skeletal muscle. The highly organized structure of skeletal muscle leads to effects that change spectral features far beyond simple peak heights, depending on the type and orientation of the muscle. Specific recommendations are given for the acquisition of three particular metabolites (intramyocellular lipids, carnosine and acetylcarnitine) and for preconditioning of experiments and instructions to study volunteers.

Dietary Carnitine and Carnosine Increase Body Lean in Healthy Cats in a Preliminary Study

Simple Summary

Cats, like mammals in general, experience lean body mass loss in later life. This study shows that two dietary interventions offset that loss: L-carnitine and carnosine. The combination did not change body lean. Interestingly, the combination resulted in an increased circulating concentration of 8 of the 10 cytokines measured, while L-carnitine alone resulted in decreased concentrations. Thus, L-carnitine could benefit the healthy cat while in some disease states it may be beneficial to increase both L-carnitine and carnosine.

Abstract

The need to maintain body lean as cats age is shown in both health and disease. In healthy cats, body lean is associated with enhanced movement and overall longevity. In many disease states (i.e., renal disease, obesity), an enhanced or minimally maximal support of body lean is associated with quality of life and is a nutritional goal in aiding in the management of the disease. This study was designed to investigate the effect of these two dietary components and their combination on body composition and circulating factors of health, including metabolomics analysis and cytokine concentration. The foods that were fed for 169 days to four groups of cats and consisted of control food (formulated to meet the nutritional needs of all adult cats), carnitine-enhanced food (control food plus 300 mg/kg L-carnitine), carnosine-enhanced food (control food plus 1000 mg/kg carnosine), and food enhanced with both (control plus 300 mg/kg carnitine and 1000 mg/kg carnosine). Dietary enhancement with L-carnitine and carnosine increased body lean at the end of the study compared to the cats consuming the control food or the combination food. The cats consuming L-carnitine alone had a decreased concentration of circulating cytokines, while those consuming the combination food had an increased concentration of glucose, pyruvate, succinate, and circulating cytokines.

Ergogenic effect of pre-exercise chicken broth ingestion on a high-intensity cycling time-trial

Background

chicken meat extract is a popular functional food in Asia. It is rich in the bioactive compounds carnosine and anserine, two histidine-containing dipeptides (HCD). Studies suggest that acute pre-exercise ingestion of chicken extracts has important applications towards exercise performance and fatigue control, but the evidence is equivocal. This study aimed to evaluate the ergogenic potential of the pre-exercise ingestion of a homemade chicken broth (CB) vs a placebo soup on a short-lasting, high-intensity cycling exercise.

Methods

fourteen men participated in this double-blind, placebo-controlled, crossover intervention study. Subjects ingested either CB, thereby receiving 46.4 mg/kg body weight of HCD, or a placebo soup (similar in taste without HCD) 40 min before an 8 min cycling time trial (TT) was performed. Venous blood samples were collected at arrival (fasted), before exercise and at 5 min recovery. Plasma HCD were measured with UPLC-MS/MS and glutathione (in red blood cells) was measured through HPLC. Capillary blood samples were collected at different timepoints before and after exercise.

Results

a significant improvement (p = 0.033; 5.2%) of the 8 min TT mean power was observed after CB supplementation compared to placebo. Post-exercise plasma carnosine (p <  0.05) and anserine (p <  0.001) was significantly increased after CB supplementation and not following placebo. No significant effect of CB supplementation was observed either on blood glutathione levels, nor on capillary blood analysis.

Conclusions

oral CB supplementation improved the 8 min TT performance albeit it did not affect the acid-base balance or oxidative status parameters. Further research should unravel the potential role and mechanisms of HCD, present in CB, in this ergogenic approach.

Metabolomic Profile of Skeletal Muscle and Its Change Under a Mixed-Mode Exercise Intervention in Progressively Dysglycemic Subjects

Skeletal muscles play an essential role in whole-body glucose homeostasis. They are a key organ system engaged in the development of insulin resistance, and also a crucial tissue mediating the beneficial metabolic effects of physical activity. However, molecular mechanisms underlying both these processes in skeletal muscle remain unclear. The aim of our study was to compare metabolomic profiles in skeletal muscle of patients at different stages of dysglycemia, from normoglycemia through prediabetes to T2D, and its changes under a mixed-mode (strength and endurance) exercise intervention. We performed targeted metabolomics comprising several major metabolite classes, including amino acids, biogenic amines and lipid subgroups in skeletal muscles of male patients. Dysglycemic groups differed significantly at baseline in lysophosphatidylcholines, phosphatidylcholines, sphingomyelins, glutamine, ornithine, and carnosine. Following the exercise intervention, we detected significant changes in lipids and metabolites related to lipid metabolism, including in ceramides and acylcarnitines. With their larger and more significant change over the intervention and among dysglycemic groups, these findings suggest that lipid species may play a predominant role in both the pathogenesis of type 2 diabetes and its protection by exercise. Simultaneously, we demonstrated that amino acid metabolism, especially glutamate dysregulation, is correlated to the development of insulin resistance and parallels disturbances in lipid metabolites.

Acute carnosine and β-alanine supplementation increase the compensated part of the ventilation versus work rate relationship during a ramp incremental cycle test in physically active men

BACKGROUND

Chronic supplementation with carnosine and β-alanine (Carn-βA) has been proposed to improve muscle contractility and reduce muscle fatigue mainly through an increase in intracellular pH buffering capacity. However, the acute ergogenic effects of Carn-βA supplementation are poorly investigated. This study aimed at evaluating the acute effects of a single Carn-βA supplementation on the cardiorespiratory and metabolic response during a ramp cycle-ergometric test.

METHODS

This randomized, double-blind, placebo-controlled study, involved 10 healthy males (age: 22.2±1.9 years, body mass: 72.5±7.9 kg, stature: 1.72±0.08 m, Body Mass Index: 24.47±1.91 kg/m², mean±standard deviation). All the participants performed two maximal incremental ramp tests on a cycle ergometer, with a prior randomized assumption of 2.5 g L-carnosine plus 2.5 g β-alanine (Carn-βA) or placebo (PLA). During exercise, gas exchange parameters were measured breath-by-breath, heart rate was monitored by electrocardiography and rate perceived exertion was determined on Borg scales. From the ramp test, peak cardiorespiratory and metabolic parameters and ventilatory thresholds (VT1 and VT2) were calculated offline.

RESULTS

No differences between the experimental conditions emerged at peak exercise. However, despite acute Carn-ßA supplementation did not affect the single ventilatory thresholds, the compensated portion of the ramp test (i.e. the difference between VT2 and VT1) was significantly larger (P=0.043) in Carn-ßA.

CONCLUSIONS

These findings demonstrate a positive effect of acute Carn-ßA supplementation on the compensated part of the exercise. This should be taken into account by nutritionists and athletes searching for nutritional supplements, when a quick effect based on an acute dose is required.

Beta-alanine supplementation in patients with COPD receiving non-linear periodised exercise training or neuromuscular electrical stimulation: protocol of two randomised, double-blind, placebo-controlled trials

INTRODUCTION

Exercise intolerance is common in patients with chronic obstructive pulmonary disease (COPD) and, although multifactorial, it is largely caused by lower-limb muscle dysfunction. Research has shown that patients with severe to very severe COPD have significantly lower levels of muscle carnosine, which acts as a pH buffer and antioxidant. Beta-alanine (BA) supplementation has been shown to consistently elevate muscle carnosine in a variety of populations and may therefore improve exercise tolerance and lower-limb muscle function. The primary objective of the current studies is to assess the beneficial effects of BA supplementation in enhancing exercise tolerance on top of two types of exercise training (non-linear periodised exercise (NLPE) training or neuromuscular electrical stimulation (NMES)) in patients with COPD.

METHODS AND ANALYSIS

Two randomised, double-blind, placebo-controlled trials have been designed. Patients will routinely receive either NLPE (BASE-TRAIN trial) or NMES (BASE-ELECTRIC trial) as part of standard exercise-based care during their 8-to-10 week pulmonary rehabilitation (PR) programme. A total of 222 patients with COPD (2×77 = 154 patients in the BASE-TRAIN trial and 2×34 = 68 patients in the BASE-ELECTRIC trial) will be recruited from two specialised PR centres in The Netherlands. For study purposes, patients will receive 3.2 g of oral BA supplementation or placebo per day. Exercise tolerance is the primary outcome, which will be assessed using the endurance shuttle walk test (BASE-TRAIN) or the constant work rate cycle test (BASE-ELECTRIC). Furthermore, quadriceps muscle strength and endurance, cognitive function, carnosine levels (in muscle), BA levels (in blood and muscle), markers of oxidative stress and inflammation (in blood, muscles and lungs), physical activity and quality of life will be measured.

ETHICS AND DISSEMINATION

Both trials were approved by CMO Regio Arnhem-Nijmegen, The Netherlands (NL70781.091.19. and NL68757.091.19).

TRIAL REGISTRATION NUMBER

NTR8427 (BASE-TRAIN) and NTR8419 (BASE-ELECTRIC).

A Distance-Based Framework for the Characterization of Metabolic Heterogeneity in Large Sets of Genome-Scale Metabolic Models

Gene expression and protein abundance data of cells or tissues belonging to healthy and diseased individuals can be integrated and mapped onto genome-scale metabolic networks to produce patient-derived models. As the number of available and newly developed genome-scale metabolic models increases, new methods are needed to objectively analyze large sets of models and to identify the determinants of metabolic heterogeneity. We developed a distance-based workflow that combines consensus machine learning and metabolic modeling techniques and used it to apply pattern recognition algorithms to collections of genome-scale metabolic models, both microbial and human. Model composition, network topology and flux distribution provide complementary aspects of metabolic heterogeneity in patient-specific genome-scale models of skeletal muscle. Using consensus clustering analysis we identified the metabolic processes involved in the individual responses to endurance training in older adults.

Effects of Beta-Alanine Supplementation on Physical Performance in Aerobic-Anaerobic Transition Zones: A Systematic Review and Meta-Analysis

Beta-alanine supplementation (BA) has a positive impact on physical performance. However, evidence showing a benefit of this amino acid in aerobic-anaerobic transition zones is scarce and the results controversial. The aim of this systematic review and meta-analysis is to analyze the effects of BA supplementation on physical performance in aerobic-anaerobic transition zones. At the same time, the effect of different dosages and durations of BA supplementation were identified. The search was designed in accordance with the PRISMA^® guidelines for systematic reviews and meta-analyses and performed in Web of Science (WOS), Scopus, SPORTDiscus, PubMed, and MEDLINE between 2010 and 2020. The methodological quality and risk of bias were evaluated with the Cochrane Collaboration tool. The main variables were the Time Trial Test (TTT) and Time to Exhaustion (TTE) tests, the latter separated into the Limited Time Test (LTT) and Limited Distance Test (LDT). The analysis was carried out with a pooled standardized mean difference (SMD) through Hedges' g test (95% CI). Nineteen studies were included in the systematic review and meta-analysis, revealing a small effect for time in the TTT (SMD, -0.36; 95% CI, -0.87-0.16; I² = 59%; p = 0.010), a small effect for LTT (SMD, 0.25; 95% CI, -0.01-0.51; I² = 0%; p = 0.53), and a large effect for LDT (SMD, 4.27; 95% CI, -0.25-8.79; I² = 94%; p = 0.00001). BA supplementation showed small effects on physical performance in aerobic-anaerobic transition zones. Evidence on acute supplementation is scarce (one study); therefore, exploration of acute supplementation with different dosages and formats on physical performance in aerobic-anaerobic transition zones is needed.

Space Flight Diet-Induced Deficiency and Response to Gravity-Free Resistive Exercise

Immune system dysregulation is among the many adverse effects incurred by astronauts during space flights. Omega-3 fatty acids, β-alanine, and carnosine are among the many nutrients that contribute to immune system health. For space flight, crewmembers are prescribed a diet with a macronutrient composition of 55% carbohydrate, 30% fat, and 15% protein. To quantify omega-3 fatty acid, β-alanine and carnosine intakes from such a diet, and to examine each nutrient's impact on exercise performance, 21 participants adhered to the aforementioned macronutrient ratio for 14 days which was immediately followed by a workout performed on gravity-independent resistive exercise hardware. Results included daily omega-3 fatty acid intakes below the suggested dietary intake. Daily omega-3 fatty acid, β-alanine and carnosine intakes each correlated with non-significant amounts of variance from the workout's volume of work. Given the nutritional requirements to maintain immune system function and the demands of in-flight exercise countermeasures for missions of increasingly longer durations current results, in combination with previously published works, imply in-flight supplementation may be a prudent approach to help address the physiological and mental challenges incurred by astronauts on future space flights.

Dietary Acid-Base Balance in High-Performance Athletes

Physical exercise leads to metabolic changes that affect the acid-base balance in skeletal muscles and other tissues. Nutrition is one of the factors that may influence the acid-base balance in the body. Keeping alkaline circumstances in the body is important not only for health and athletic performance in training but also during competition in many sport events. This is especially significant for athletes who practice in sport at the highest level of competition. The aim of the study was to determine the dietary acid-base balance in competitive Lithuanian high-performance athletes, and to evaluate the effect of actual diets of athletes on NEAP (net endogenous acid production), muscle mass and body mineral content during a four-year Olympic cycle. The research participants were 18.1 ± 3.3-year-old Lithuanian high performance athletes (n = 323). The actual diet was investigated using the 24 h recall dietary survey method. The measurements of body composition were performed using BIA (bioelectrical impedance analysis). The potential renal acid load of the diets of athletes (dietary PRAL) and NEAP were calculated. In 10.2% of athletes, NEAP exceeds 100 mEq · day-1 and is on average 126.1 ± 32.7 mEq · day-1. Higher NEAP in athletes is associated with lower muscle mass (β -1.2% of body weight, p < 0.001) but has no effect on the amount of minerals in the body (β 0.01% of body weight, p = 0.073). Overall, 25-30% of Lithuanian high-performance athletes use high-protein diets (2.0-4.8 g · kg-1 · day-1) leading to a dietary acid-base imbalance as well as an excessive production of endogenous acids in the body. Athletes are recommended to consume higher amounts of potassium and magnesium. An increase in calcium intake up to 1500 mg per day is recommended. In exceptional cases, periodised nutrition for athletes may involve diets complemented with bicarbonate and/or beta-alanine supplements.

Histidine in Health and Disease: Metabolism, Physiological Importance, and Use as a Supplement

L-histidine (HIS) is an essential amino acid with unique roles in proton buffering, metal ion chelation, scavenging of reactive oxygen and nitrogen species, erythropoiesis, and the histaminergic system. Several HIS-rich proteins (e.g., haemoproteins, HIS-rich glycoproteins, histatins, HIS-rich calcium-binding protein, and filaggrin), HIS-containing dipeptides (particularly carnosine), and methyl- and sulphur-containing derivatives of HIS (3-methylhistidine, 1-methylhistidine, and ergothioneine) have specific functions. The unique chemical properties and physiological functions are the basis of the theoretical rationale to suggest HIS supplementation in a wide range of conditions. Several decades of experience have confirmed the effectiveness of HIS as a component of solutions used for organ preservation and myocardial protection in cardiac surgery. Further studies are needed to elucidate the effects of HIS supplementation on neurological disorders, atopic dermatitis, metabolic syndrome, diabetes, uraemic anaemia, ulcers, inflammatory bowel diseases, malignancies, and muscle performance during strenuous exercise. Signs of toxicity, mutagenic activity, and allergic reactions or peptic ulcers have not been reported, although HIS is a histamine precursor. Of concern should be findings of hepatic enlargement and increases in ammonia and glutamine and of decrease in branched-chain amino acids (valine, leucine, and isoleucine) in blood plasma indicating that HIS supplementation is inappropriate in patients with liver disease.

β-Alanine and l-histidine supplementation associated with combined training increased functional capacity and maximum strength in heart failure rats

NEW FINDINGS

What is the central question of the study? Does β-alanine with l-histidine supplementation associated with endurance and strength training improve echocardiographic parameters, functional capacity, and maximum strength in rats with chronic heart failure? What is the main finding and its importance? β-Alanine with l-histidine supplementation associated with endurance and strength training increased functional capacity and maximum strength through increasing exercise capacity peripherally but did not affect echocardiographic parameters in rats with chronic heart failure. Combined training (CT) has been associated with positive responses in the clinical status of patients with chronic heart failure (CHF). Other non-pharmacological tools, such as amino acid supplementation, may further enhance its adaptation. However, the effects of β-alanine and l-histidine supplementation in CHF remain unclear. In the present study, the aim was to test whether supplementing carnosine precursors with CT could give improved responses in the functional capacity and echocardiographic variables of rats with CHF. Twenty-four Wistar rats, were submitted to myocardial infarction and allocated to three groups: animals with CHF kept in sedentary conditions (SED, n = 8), animals with CHF submitted to CT in strength and aerobic exercise supplemented with placebo (CT-P, n = 8) and animals with CHF submitted to CT in strength and aerobic exercise supplemented with β-alanine and l-histidine (CT-S, n = 8). The trained animals were submitted to a strength protocol three times per week with intensity of 65-75% of one repetition maximum test. Aerobic training was conducted two times per week (50 min, 15 m min^-1 ). The supplemented group received β-alanine and l-histidine orally (each 250 mg kg^-1  day^-1 ). No changes in echocardiographic and morphological parameters were found among the groups (P > 0.05). Functional capacity, Δ V ̇ O 2 max and maximum strength were higher in CT-P than in SED and even higher in CT-S than in CT-P (P < 0.01). The CT was able to improve functional capacity, but the supplementation was shown to enhance these parameters even further in the CHF rats. We conclude that the increase in functional capacity and strength gained through CT and supplementation were associated with the improvement in peripheral parameters with no changes in cardiac variables.

Effect of β-alanine supplementation during high-intensity interval training on repeated sprint ability performance and neuromuscular fatigue

The study investigated the influence of β-alanine supplementation during a high-intensity interval training (HIIT) program on repeated sprint ability (RSA) performance. This study was randomized, double-blinded, and placebo controlled. Eighteen men performed an incremental running test until exhaustion (TINC) at baseline and followed by 4-wk HIIT (10 × 1-min runs 90% maximal TINCvelocity [1-min recovery]). Then, participants were randomized into two groups and performed a 6-wk HIIT associated with supplementation of 6.4 g/day of β-alanine (Gβ) or dextrose (placebo group; GP). Pre- and post-6-wk HIIT + supplementation, participants performed the following tests: 1) TINC; 2) supramaximal running test; and 3) 2 × 6 × 35-m sprints (RSA). Before and immediately after RSA, neuromuscular function was assessed by vertical jumps, maximal isometric voluntary contractions of knee extension, and neuromuscular electrical stimulations. Muscle biopsies were performed to determine muscle carnosine content, muscle buffering capacity in vitro (βmin vitro), and content of phosphofructokinase (PFK), monocarboxylate transporter 4 (MCT4), and hypoxia-inducible factor-1α (HIF-1α). Both groups showed a significant time effect for maximal oxygen uptake (Gβ: 6.2 ± 3.6% and GP: 6.5 ± 4.2%; P > 0.01); only Gβ showed a time effect for total (−3.0 ± 2.0%; P = 0.001) and best (−3.3 ± 3.0%; P = 0.03) RSA times. A group-by-time interaction was shown after HIIT + Supplementation for muscle carnosine (Gβ: 34.4 ± 2.3 mmol·kg−1·dm−1and GP: 20.7 ± 3.0 mmol·kg−1·dm−1; P = 0.003) and neuromuscular voluntary activation after RSA (Gβ: 87.2 ± 3.3% and GP: 78.9 ± 12.4%; P = 0.02). No time effect or group-by-time interaction was shown for supramaximal running test performance, βm, and content of PFK, MCT4, and HIF-1α. In summary, β-alanine supplementation during HIIT increased muscle carnosine and attenuated neuromuscular fatigue, which may contribute to an enhancement of RSA performance.

NEW & NOTEWORTHY β-Alanine supplementation during a high-intensity interval training program increased repeated sprint performance. The improvement of muscle carnosine content induced by β-alanine supplementation may have contributed to an attenuation of central fatigue during repeated sprint. Overall, β-alanine supplementation may be a useful dietary intervention to prevent fatigue.