A balanced formula of essential amino acids promotes brain mitochondrial biogenesis and protects neurons from ischemic insult.

Mitochondrial dysfunction plays a key role in the aging process, and aging is a strong risk factor for neurodegenerative diseases or brain injury characterized by impairment of mitochondrial function. Among these, ischemic stroke is one of the leading causes of death and permanent disability worldwide. Pharmacological approaches for its prevention and therapy are limited. Although non-pharmacological interventions such as physical exercise, which promotes brain mitochondrial biogenesis, have been shown to exert preventive effects against ischemic stroke, regular feasibility is complex in older people, and nutraceutical strategies could be valuable alternatives. We show here that dietary supplementation with a balanced essential amino acid mixture (BCAAem) increased mitochondrial biogenesis and the endogenous antioxidant response in the hippocampus of middle-aged mice to an extent comparable to those elicited by treadmill exercise training, suggesting BCAAem as an effective exercise mimetic on brain mitochondrial health and disease prevention. In vitro BCAAem treatment directly exerted mitochondrial biogenic effects and induced antioxidant enzyme expression in primary mouse cortical neurons. Further, exposure to BCAAem protected cortical neurons from the ischemic damage induced by an in vitro model of cerebral ischemia (oxygen-glucose deprivation, OGD). BCAAem-mediated protection against OGD was abolished in the presence of rapamycin, Torin-1, or L-NAME, indicating the requirement of both mTOR and eNOS signaling pathways in the BCAAem effects. We propose BCAAem supplementation as an alternative to physical exercise to prevent brain mitochondrial derangements leading to neurodegeneration and as a nutraceutical intervention aiding recovery after cerebral ischemia in conjunction with conventional drugs.

Efficacy and tolerability of a specific blend of amino acids in patients with anorexia nervosa treated in a hospital setting: study protocol for a randomized controlled trial.

BACKGROUND: Specific blends of essential amino acids (EAA) containing a high percentage of branched-chain amino acids preserves mitochondrial metabolism and higher physical resistance in elderly mice, increasing their survival and improving physical performance and cognitive functions in malnourished elderly patients. However, no study has been yet done on patients with anorexia nervosa (AN) who regain weight with specialized intensive treatment. The present study aims to evaluate the efficacy of supplementation with EAA on the change in lean body mass (LBM) and other physical and psychological outcomes in patients with AN who are undergoing specialist treatment for eating disorders. METHODS: This is a 13-week randomized, double-blind, placebo-controlled study. Patients will be randomized to either a mixture of a complex blend of EAA and intermediates of the tricarboxylic acid (TCA) cycle (citrate, malate, succinate) supplementation (or placebo) upon admission at the intensive residential and day-hospital treatment for eating disorders. Ninety-two participants with AN aged 16-50 years will be recruited from a specialized intensive treatment of eating disorders. Double-blind assessment will be conducted at baseline (T0) and the end of the 13 weeks of treatment (T1). The study's primary aim is to evaluate the efficacy of supplementation with EAA and TCA intermediates on the change in lean body mass (LBM) with weight restoration in patients with AN who are undergoing specialist treatment for eating disorders. The secondary aims of the study are to assess the effect of dietary supplementation on physical fitness, weight restoration, modification of AN and general psychopathology, and psychosocial impairment. DISCUSSION: The study's results will inform researchers and clinicians on whether supplementing a mixture of EAA and TCA cycle intermediates will improve the increase of LBM and other important physical and psychological outcomes in patients with AN who regain weight with specialized intensive treatment. TRIAL REGISTRATION: NCT, NCT05290285. Registered on 22 March 2022.

Dietary essential amino acids for the treatment of heart failure with reduced ejection fraction.

AIMS: Heart failure with reduced ejection fraction (HFrEF) is a leading cause of mortality worldwide, requiring novel therapeutic and lifestyle interventions. Metabolic alterations and energy production deficit are hallmarks and thereby promising therapeutic targets for this complex clinical syndrome. We aim to study the molecular mechanisms and effects on cardiac function in rodents with HFrEF of a designer diet in which free essential amino acids-in specifically designed percentages-substituted for protein. METHODS AND RESULTS: Wild-type mice were subjected to transverse aortic constriction (TAC) to induce left ventricle (LV) pressure overload or sham surgery. Whole-body glucose homeostasis was studied with glucose tolerance test, while myocardial dysfunction and fibrosis were measured with echocardiogram and histological analysis. Mitochondrial bioenergetics and morphology were investigated with oxygen consumption rate measurement and electron microscopy evaluation. Circulating and cardiac non-targeted metabolite profiles were analyzed by ultrahigh performance liquid chromatography-tandem mass spectroscopy, while RNA-sequencing was used to identify signalling pathways mainly affected. The amino acid-substituted diet shows remarkable preventive and therapeutic effects. This dietary approach corrects the whole-body glucose metabolism and restores the unbalanced metabolic substrate usage-by improving mitochondrial fuel oxidation-in the failing heart. In particular, biochemical, molecular, and genetic approaches suggest that renormalization of branched-chain amino acid oxidation in cardiac tissue, which is suppressed in HFrEF, plays a relevant role. Beyond the changes of systemic metabolism, cell-autonomous processes may explain at least in part the diet's cardioprotective impact. CONCLUSION: Collectively, these results suggest that manipulation of dietary amino acids, and especially essential amino acids, is a potential adjuvant therapeutic strategy to treat systolic dysfunction and HFrEF in humans.

Amino Acids in Cancer and Cachexia: An Integrated View.

Rapid tumor growth requires elevated biosynthetic activity, supported by metabolic rewiring occurring both intrinsically in cancer cells and extrinsically in the cancer host. The Warburg effect is one such example, burning glucose to produce a continuous flux of biomass substrates in cancer cells at the cost of energy wasting metabolic cycles in the host to maintain stable glycemia. Amino acid (AA) metabolism is profoundly altered in cancer cells, which use AAs for energy production and for supporting cell proliferation. The peculiarities in cancer AA metabolism allow the identification of specific vulnerabilities as targets of anti-cancer treatments. In the current review, specific approaches targeting AAs in terms of either deprivation or supplementation are discussed. Although based on opposed strategies, both show, in vitro and in vivo, positive effects. Any AA-targeted intervention will inevitably impact the cancer host, who frequently already has cachexia. Cancer cachexia is a wasting syndrome, also due to malnutrition, that compromises the effectiveness of anti-cancer drugs and eventually causes the patient's death. AA deprivation may exacerbate malnutrition and cachexia, while AA supplementation may improve the nutritional status, counteract cachexia, and predispose the patient to a more effective anti-cancer treatment. Here is provided an attempt to describe the AA-based therapeutic approaches that integrate currently distant points of view on cancer-centered and host-centered research, providing a glimpse of several potential investigations that approach cachexia as a unique cancer disease.

A designer mixture of six amino acids promotes the extracellular matrix gene expression in cultured human fibroblasts.

The deterioration of the skin is caused by dermatological disorders, environmental conditions, and aging processes. One incisive strategy for supervising the skin aging process is implementing healthy nutrition, preserving a balanced diet, and a good supply of food supplements. Here, we compared H-Pro-Hyp-OH peptide, hydrolyzed collagen, and an original mixture of six amino acids (we named 6aa)-including glycine, l-alanine, l-proline, l-valine, l-leucine, and l-lysine-effects on the production of extracellular matrix (ECM) components, particularly the elastin, fibronectin, collagen 1, and collagen 4. Treatment of BJ human skin fibroblasts with the 6aa mixture upregulated elastin, fibronectin, and collagen 1 gene expression, without affecting the expression of anti-reactive oxygen species enzymes. Moreover, the mammalian target of rapamycin (mTOR) signaling pathway seems to be involved, at least in part. Collectively, these results suggest that the six amino acid mixture exerts beneficial effects in human skin fibroblasts.

An amino acid-defined diet impairs tumour growth in mice by promoting endoplasmic reticulum stress and mTOR inhibition.

OBJECTIVE: Profound metabolic alterations characterize cancer development and, beyond glucose addiction, amino acid (AA) dependency is now recognized as a hallmark of tumour growth. Therefore, targeting the metabolic addiction of tumours by reprogramming their substrate utilization is an attractive therapeutic strategy. We hypothesized that a dietary approach targeted to stimulate oxidative metabolism could reverse the metabolic inflexibility of tumours and represent a proper adjuvant therapy. METHODS: We measured tumour development in xenografted mice fed with a designer, casein-deprived diet enriched in free essential amino acids (EAAs; SFA-EAA diet), or two control isocaloric, isolipidic, and isonitrogenous diets, identical to the SFA-EAA diet except for casein presence (SFA diet), or casein replacement by the free AA mixture designed on the AA profile of casein (SFA-CAA diet). Moreover, we investigated the metabolic, biochemical, and molecular effects of two mixtures that reproduce the AA composition of the SFA-EAA diet (i.e., EAAm) and SFA-CAA diet (i.e., CAAm) in diverse cancer and non-cancer cells. RESULTS: The SFA-EAA diet reduced tumour growth in vivo, promoted endoplasmic reticulum (ER) stress, and inhibited mechanistic/mammalian target of rapamycin (mTOR) activity in the tumours. Accordingly, in culture, the EAAm, but not the CAAm, activated apoptotic cell death in cancer cells without affecting the survival and proliferation of non-cancer cells. The EAAm increased branched-chain amino acid (BCAA) oxidation and decreased glycolysis, ATP levels, redox potential, and intracellular content of selective non-essential amino acids (NEAA) in cancer cells. The EAAm-induced NEAA starvation activated the GCN2-ATF4 stress pathway, leading to ER stress, mTOR inactivation, and apoptosis in cancer cells, unlike non-cancer cells. CONCLUSION: Together, these results confirm the efficacy of specific EAA mixtures in promoting cancer cells' death and suggest that manipulation of dietary EAA content and profile could be a valuable support to the standard chemotherapy for specific cancers.

COVID-19 and Hartnup disease: an affair of intestinal amino acid malabsorption.

Since the outbreak of COVID-19, clinicians have tried every effort to fight the disease, and multiple drugs have been proposed. However, no proven effective therapies currently exist, and different clinical phenotypes complicate the situation. In clinical practice, many severe or critically ill COVID-19 patients developed gastrointestinal (GI) disturbances, including vomiting, diarrhoea, or abdominal pain, even in the absence of cough and dyspnea. Understanding the mechanism of GI disturbances is warranted for exploring better clinical care for COVID-19 patients. With evidence collected from clinical studies on COVID-19 and basic research on a rare genetic disease (i.e., Hartnup disorder), we put forward a novel hypothesis to elaborate an effective nutritional therapy. We hypothesize that SARS-CoV-2 spike protein, binding to intestinal angiotensin-converting enzyme 2, negatively regulates the absorption of neutral amino acids, and this could explain not only the GI, but also systemic disturbances in COVID-19. Amino acid supplements could be recommended.Level of evidence No level of evidence: Hypothesis article.

Complete neural stem cell (NSC) neuronal differentiation requires a branched chain amino acids-induced persistent metabolic shift towards energy metabolism.

Neural stem cell (NSC) neuronal differentiation requires a metabolic shift towards oxidative phosphorylation. We now show that a branched-chain amino acids-driven, persistent metabolic shift toward energy metabolism is required for full neuronal maturation. We increased energy metabolism of differentiating neurons derived both from murine NSCs and human induced pluripotent stem cells (iPSCs) by supplementing the cell culture medium with a mixture composed of branched-chain amino acids, essential amino acids, TCA cycle precursors and co-factors. We found that treated differentiating neuronal cells with enhanced energy metabolism increased: i) total dendritic length; ii) the mean number of branches and iii) the number and maturation of the dendritic spines. Furthermore, neuronal spines in treated neurons appeared more stable with stubby and mushroom phenotype and with increased expression of molecules involved in synapse formation. Treated neurons modified their mitochondrial dynamics increasing the mitochondrial fusion and, consistently with the increase of cellular ATP content, they activated cellular mTORC1 dependent p70S6 K1 anabolism. Global transcriptomic analysis further revealed that treated neurons induce Nrf2 mediated gene expression. This was correlated with a functional increase in the Reactive Oxygen Species (ROS) scavenging mechanisms. In conclusion, persistent branched-chain amino acids-driven metabolic shift toward energy metabolism enhanced neuronal differentiation and antioxidant defences. These findings offer new opportunities to pharmacologically modulate NSC neuronal differentiation and to develop effective strategies for treating neurodegenerative diseases.

A Special Amino-Acid Formula Tailored to Boosting Cell Respiration Prevents Mitochondrial Dysfunction and Oxidative Stress Caused by Doxorubicin in Mouse Cardiomyocytes.

Anthracycline anticancer drugs, such as doxorubicin (DOX), can induce cardiotoxicity supposed to be related to mitochondrial damage. We have recently demonstrated that a branched-chain amino acid (BCAA)-enriched mixture (BCAAem), supplemented with drinking water to middle-aged mice, was able to promote mitochondrial biogenesis in cardiac and skeletal muscle. To maximally favor and increase oxidative metabolism and mitochondrial function, here we tested a new original formula, composed of essential amino acids, tricarboxylic acid cycle precursors and co-factors (named 5), in HL-1 cardiomyocytes and mice treated with DOX. We measured mitochondrial biogenesis, oxidative stress, and BCAA catabolic pathway. Moreover, the molecular relevance of endothelial nitric oxide synthase (eNOS) and mechanistic/mammalian target of rapamycin complex 1 (mTORC1) was studied in both cardiac tissue and HL-1 cardiomyocytes. Finally, the role of Krüppel-like factor 15 (KLF15), a critical transcriptional regulator of BCAA oxidation and eNOS-mTORC1 signal, was investigated. Our results demonstrate that the 5 mixture prevents the DOX-dependent mitochondrial damage and oxidative stress better than the previous BCAAem, implying a KLF15/eNOS/mTORC1 signaling axis. These results could be relevant for the prevention of cardiotoxicity in the DOX-treated patients.

From mitochondria to healthy aging: The role of branched-chain amino acids treatment: MATeR a randomized study.

RATIONALE: Malnutrition often affects elderly patients and significantly contributes to the reduction in healthy life expectancy, causing high morbidity and mortality. In particular, protein malnutrition is one of the determinants of frailty and sarcopenia in elderly people. METHODS: To investigate the role of amino acid supplementation in senior patients we performed an open-label randomized trial and administered a particular branched-chain amino acid enriched mixture (BCAAem) or provided diet advice in 155 elderly malnourished patients. They were followed for 2 months, assessing cognitive performance by Mini Mental State Examination (MMSE), muscle mass measured by anthropometry, strength measure by hand grip and performance measured by the Timed Up and Go (TUG) test, the 30 s Chair Sit to Stand (30-s CST) test and the 4 m gait speed test. Moreover we measured oxidative stress in plasma and mitochondrial production of ATP and electron flux in peripheral blood mononuclear cells. RESULTS: Both groups improved in nutritional status, general health and muscle mass, strength and performance; treatment with BCAAem supplementation was more effective than simple diet advice in increasing MMSE (1.2 increase versus 0.2, p = 0.0171), ATP production (0.43 increase versus -0.1, p = 0.0001), electron flux (0.50 increase versus 0.01, p < 0.0001) and in maintaining low oxidative stress. The amelioration of clinical parameters as MMSE, balance, four meter walking test were associated to increased mitochondrial function. CONCLUSIONS: Overall, our findings show that sustaining nutritional support might be clinically relevant in increasing physical performance in elderly malnourished patients and that the use of specific BCAAem might ameliorate also cognitive performance thanks to an amelioration of mitochondria bioenergetics.

Supplementation with a selective amino acid formula ameliorates muscular dystrophy in mdx mice.

Duchenne muscular dystrophy (DMD) is one of the most common and severe forms of muscular dystrophy. Oxidative myofibre content, muscle vasculature architecture and exercise tolerance are impaired in DMD. Several studies have demonstrated that nutrient supplements ameliorate dystrophic features, thereby enhancing muscle performance. Here, we report that dietary supplementation with a specific branched-chain amino acid-enriched mixture (BCAAem) increased the abundance of oxidative muscle fibres associated with increased muscle endurance in dystrophic mdx mice. Amelioration of the fatigue index in BCAAem-treated mdx mice was caused by a cascade of events in the muscle tissue, which were promoted by endothelial nitric oxide synthase (eNOS) activation and vascular endothelial growth factor (VEGF) expression. VEGF induction led to recruitment of bone marrow (BM)-derived endothelial progenitors (EPs), which increased the capillary density of dystrophic skeletal muscle. Functionally, BCAAem mitigated the dystrophic phenotype of mdx mice without inducing dystrophin protein expression or replacing the dystrophin-associated glycoprotein (DAG) complex in the membrane, which is typically lost in DMD. BCAAem supplementation could be an effective adjuvant strategy in DMD treatment.

A specific amino acid formula prevents alcoholic liver disease in rodents.

Chronic alcohol consumption promotes mitochondrial dysfunction, oxidative stress, defective protein metabolism, and fat accumulation in hepatocytes (liver steatosis). Inadequate amino acid metabolism is worsened by protein malnutrition, frequently present in alcohol-consuming patients, with reduced circulating branched-chain amino acids (BCAAs). Here we asked whether dietary supplementation with a specific amino acid mixture, enriched in BCAAs (BCAAem) and able to promote mitochondrial function in muscle of middle-aged rodents, would prevent mitochondrial dysfunction and liver steatosis in Wistar rats fed on a Lieber-DeCarli ethanol (EtOH)-containing liquid diet. Supplementation of BCAAem, unlike a mixture based on the amino acid profile of casein, abrogated the EtOH-induced fat accumulation, mitochondrial impairment, and oxidative stress in liver. These effects of BCAAem were accompanied by normalization of leucine, arginine, and tryptophan levels, which were reduced in liver of EtOH-consuming rats. Moreover, although the EtOH exposure of HepG2 cells reduced mitochondrial DNA, mitochondrial transcription factors, and respiratory chain proteins, the BCAAem but not casein-derived amino acid supplementation halted this mitochondrial toxicity. Nicotinamide adenine dinucleotide levels and sirtuin 1 (Sirt1) expression, as well as endothelial nitric oxide (eNOS) and mammalian/mechanistic target of rapamycin (mTOR) signaling pathways, were downregulated in the EtOH-exposed HepG2 cells. BCAAem reverted these molecular defects and the mitochondrial dysfunction, suggesting that the mitochondrial integrity obtained with the amino acid supplementation could be mediated through a Sirt1-eNOS-mTOR pathway. Thus a dietary activation of the mitochondrial biogenesis and function by a specific amino acid supplement protects against the EtOH toxicity and preserves the liver integrity in mammals. NEW & NOTEWORTHY Dietary supplementation of a specific amino acid formula prevents both fat accumulation and mitochondrial dysfunction in hepatocytes of alcohol-consuming rats. These effects are accompanied also by increased expression of anti-reactive oxygen species genes. The amino acid-protective effects likely reflect activation of sirtuin 1-endothelial nitric oxide synthase-mammalian target of rapamycin pathway able to regulate the cellular energy balance of hepatocytes exposed to chronic, alcoholic damage.

Amino acid supplements and metabolic health: a potential interplay between intestinal microbiota and systems control.

Dietary supplementation of essential amino acids (EAAs) has been shown to promote healthspan. EAAs regulate, in fact, glucose and lipid metabolism and energy balance, increase mitochondrial biogenesis, and maintain immune homeostasis. Basic science and epidemiological results indicate that dietary macronutrient composition affects healthspan through multiple and integrated mechanisms, and their effects are closely related to the metabolic status to which they act. In particular, EAA supplementation can trigger different and even opposite effects depending on the catabolic and anabolic states of the organisms. Among others, gut-associated microbial communities (referred to as gut microbiota) emerged as a major regulator of the host metabolism. Diet and host health influence gut microbiota, and composition of gut microbiota, in turn, controls many aspects of host health, including nutrient metabolism, resistance to infection, and immune signals. Altered communication between the innate immune system and the gut microbiota might contribute to complex diseases. Furthermore, gut microbiota and its impact to host health change largely during different life phases such as lactation, weaning, and aging. Here we will review the accumulating body of knowledge on the impact of dietary EAA supplementation on the host metabolic health and healthspan from a holistic perspective. Moreover, we will focus on the current efforts to establish causal relationships among dietary EAAs, gut microbiota, and health during human development.

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.

A Peculiar Formula of Essential Amino Acids Prevents Rosuvastatin Myopathy in Mice.

AIMS: Myopathy, characterized by mitochondrial oxidative stress, occurs in ∼10% of statin-treated patients, and a major risk exists with potent statins such as rosuvastatin (Rvs). We sought to determine whether a peculiar branched-chain amino acid-enriched mixture (BCAAem), found to improve mitochondrial function and reduce oxidative stress in muscle of middle-aged mice, was able to prevent Rvs myopathy. RESULTS: Dietary supplementation of BCAAem was able to prevent the structural and functional alterations of muscle induced by Rvs in young mice. Rvs-increased plasma 3-methylhistidine (a marker of muscular protein degradation) was prevented by BCAAem. This was obtained without changes of Rvs ability to reduce cholesterol and triglyceride levels in blood. Rather, BCAAem promotes de novo protein synthesis and reduces proteolysis in cultured myotubes. Morphological alterations of C2C12 cells induced by statin were counteracted by amino acids, as were the Rvs-increased atrogin-1 mRNA and protein levels. Moreover, BCAAem maintained mitochondrial mass and density and citrate synthase activity in skeletal muscle of Rvs-treated mice beside oxygen consumption and ATP levels in C2C12 cells exposed to statin. Notably, BCAAem assisted Rvs to reduce oxidative stress and to increase the anti-reactive oxygen species (ROS) defense system in skeletal muscle. Innovation and Conclusions: The complex interplay between proteostasis and antioxidant properties may underlie the mechanism by which a specific amino acid formula preserves mitochondrial efficiency and muscle health in Rvs-treated mice. Strategies aimed at promoting protein balance and controlling mitochondrial ROS level may be used as therapeutics for the treatment of muscular diseases involving mitochondrial dysfunction, such as statin myopathy. Antioxid. Redox Signal. 25, 595-608.

Creatine, L-carnitine, and ω3 polyunsaturated fatty acid supplementation from healthy to diseased skeletal muscle.

Myopathies are chronic degenerative pathologies that induce the deterioration of the structure and function of skeletal muscle. So far a definitive therapy has not yet been developed and the main aim of myopathy treatment is to slow the progression of the disease. Current nonpharmacological therapies include rehabilitation, ventilator assistance, and nutritional supplements, all of which aim to delay the onset of the disease and relieve its symptoms. Besides an adequate diet, nutritional supplements could play an important role in the treatment of myopathic patients. Here we review the most recent in vitro and in vivo studies investigating the role supplementation with creatine, L-carnitine, and ω3 PUFAs plays in myopathy treatment. Our results suggest that these dietary supplements could have beneficial effects; nevertheless continued studies are required before they could be recommended as a routine treatment in muscle diseases.

Dietary supplementation with essential amino acids boosts the beneficial effects of rosuvastatin on mouse kidney.

The effects of high-potency statins on renal function are controversial. To address the impact of statins on renal morpho-functional aspects, normotensive young mice were treated with rosuvastatin (Rvs). Moreover, because statins may impair mitochondrial function, mice received either dietary supplementation with an amino acid mixture enriched in essential amino acids (EAAm), which we previously demonstrated to increase mitochondrial biogenesis in muscle or an unsupplemented control diet for 1 month. Mitochondrial biogenesis and function, apoptosis, and insulin signaling pathway events were studied, primarily in cortical proximal tubules. By electron microscopy analysis, mitochondria were more abundant and more heterogeneous in size, with dense granules in the inner matrix, in Rvs- and Rvs plus EAAm-treated animals. Rvs administration increased protein kinase B and endothelial nitric oxide synthase phosphorylation, but the mammalian target of rapamycin signaling pathway was not affected. Rvs increased the expression of sirtuin 1, peroxisome proliferator-activated receptor γ coactivator-1α, cytochrome oxidase type IV, cytochrome c, and mitochondrial biogenesis markers. Levels of glucose-regulated protein 75 (Grp75), B-cell lymphoma 2, and cyclin-dependent kinase inhibitor 1 were increased in cortical proximal tubules, and expression of the endoplasmic reticulum-mitochondrial chaperone Grp78 was decreased. EAAm supplementation maintained or enhanced these changes. Rvs promotes mitochondrial biogenesis, with a probable anti-apoptotic effect. EAAm boosts these processes and may contribute to the efficient control of cellular energetics and survival in the mouse kidney. This suggests that appropriate nutritional interventions may enhance the beneficial actions of Rvs, and could potentially prevent chronic renal side effects.

Branched-chain amino acids, mitochondrial biogenesis, and healthspan: an evolutionary perspective.

Malnutrition is common among older persons, with important consequences increasing frailty and morbidity and reducing health expectancy. On the contrary, calorie restriction (CR, a low-calorie dietary regimen with adequate nutrition) slows the progression of age-related diseases and extends the lifespan of many species. Identification of strategies mimicking key CR mechanisms - increased mitochondrial respiration and reduced production of oxygen radicals - is a hot topic in gerontology. Dietary supplementation with essential and/or branched chain amino acids (BCAAs) exerts a variety of beneficial effects in experimental animals and humans and has been recently demonstrated to support cardiac and skeletal muscle mitochondrial biogenesis, prevent oxidative damage, and enhance physical endurance in middle-aged mice, resulting in prolonged survival. Here we review recent studies addressing the possible role of BCAAs in energy metabolism and in the longevity of species ranging from unicellular organisms to mammals. We also summarize observations from human studies supporting the exciting hypothesis that dietary BCAA enriched mixture supplementation might be a health-promoting strategy in aged patients at risk.

Amino acids and mitochondrial biogenesis.

Mitochondria are sources of energy production through their role in producing adenosine triphosphate for cell metabolism. Defective mitochondrial biogenesis and function play relevant roles in the pathophysiology of relevant diseases, including obesity, diabetes mellitus, myopathies, and neurodegenerative diseases. Their function is the product of synthesis of macromolecules within the mitochondria and import of proteins and lipids synthesized outside the organelles. Both are required for mitochondrial proliferation and may also facilitate the growth of preexisting mitochondria. Recent evidence indicates that these events are regulated in a complex way by several agonists and environmental conditions, through activation of specific signaling pathways and transcription factors. Nitric oxide (NO) appears to be a novel modulator of mitochondrial biogenesis. High levels of NO acutely inhibit cell respiration by binding to cytochrome c oxidase. Conversely, chronic, low-grade increases of NO stimulate mitochondrial biogenesis in diverse cell types. Here, we suggest that some types of nutrients, including specific mixtures of amino acids, may improve mitochondrial biogenesis and energy production in energy-defective conditions by increasing endothelial NO synthase expression.

Morphometric changes induced by amino acid supplementation in skeletal and cardiac muscles of old mice.

Aging is associated with progressive structural disorganization of muscular and cardiac fibers, decreasing functional capacity, and increased rates of disease and death. Aging is also characterized by disturbances in protein synthesis with impaired cellular organelle functions, particularly in the mitochondria. The availability of amino acids is a key factor for the overall metabolism of mammals and exogenous supplements of amino acid mixtures (AAm) could be a valid therapeutic strategy to improve quality of life, avoiding malnutrition and muscle wasting in the elderly. We investigated the morphoquantitative effects of long-term AAm supplementation on the mitochondria and sarcomeres (by electron microscope) and on collagen matrix deposition (by histologic techniques) in both skeletal and cardiac muscles of young and aged mice. Our data showed that old animals have fewer mitochondria and massive fibrosis in both muscles. Long-term AAm supplementation increased the number and volume of mitochondria and sarcomeres and decreased fibrosis in both skeletal muscle and hearts in old rats. These findings indicate that AAm restored muscular morphologic parameters and probably improved the mechanical performance of these organs.