Nuclear factor (erythroid derived 2)-like 2 activation increases exercise endurance capacity via redox modulation in skeletal muscles

Unlocking peak performance: The role of Nrf2 in enhancing exercise outcomes and training adaptation in humans

Since the discovery of the nuclear factor erythroid-derived 2-like 2 (Nrf2) transcription factor thirty years ago, it has been shown that it regulates more than 250 genes involved in a multitude of biological processes, including redox balance, mitochondrial biogenesis, metabolism, detoxification, cytoprotection, inflammation, immunity, autophagy, cell differentiation, and xenobiotic metabolism. In skeletal muscle, Nrf2 signalling is primarily activated in response to perturbation of redox balance by reactive oxygen species or electrophiles. Initial investigations into human skeletal muscle Nrf2 responses to exercise, dating back roughly a decade, have consistently indicated that exercise-induced ROS production stimulates Nrf2 signalling. Notably, recent studies employing Nrf2 knockout mice have revealed impaired skeletal muscle contractile function characterised by reduced force output and increased fatigue susceptibility compared to wild-type counterparts. These deficiencies partially stem from diminished basal mitochondrial respiratory capacity and an impaired capacity to upregulate specific mitochondrial proteins in response to training, findings corroborated by inducible muscle-specific Nrf2 knockout models. In humans, baseline Nrf2 expression in skeletal muscle correlates with maximal oxygen uptake and high-intensity exercise performance. This manuscript delves into the mechanisms underpinning Nrf2 signalling in response to acute exercise in human skeletal muscle, highlighting the involvement of ROS, antioxidants and Keap1/Nrf2 signalling in exercise performance. Furthermore, it explores Nrf2's role in mediating adaptations to chronic exercise and its impact on overall exercise performance. Additionally, the influence of diet and certain supplements on basal Nrf2 expression and its role in modulating acute and chronic exercise responses are briefly addressed.

Sulforaphane enhanced muscle growth by promoting lipid oxidation through modulating key signaling pathways

Sulforaphane (SFN) has shown diverse effects on human health and diseases. SFN was administered daily to C57BL/6J mice at doses of 1 mg/kg (SFN1) and 3 mg/kg (SFN3) for 8 weeks. Both doses of SFN accelerated body weight increment. The cross-sectional area and diameter of Longissimus dorsi (LD) muscle fibers were enlarged in SFN3 group. Triglyceride (TG) and total cholesterol (TC) levels in LD muscle were decreased in SFN groups. RNA sequencing results revealed that 2455 and 2318 differentially expressed genes (DEGs) were found in SFN1 and SFN3 groups, respectively. Based on GO enrichment analysis, 754 and 911 enriched GO terms in the SFN1 and SFN3 groups, respectively. KEGG enrichment analysis shown that one KEGG pathway was enriched in the SFN1 group, while six KEGG pathways were enriched in the SFN3 group. The expressions of nine selected DEGs validated with qRT-PCR were in line with the RNA sequencing data. Furthermore, SFN treatment influenced lipid and protein metabolism related pathways including AMPK signaling, fatty acid metabolism signaling, cholesterol metabolism signalling, PPAR signaling, peroxisome signaling, TGFβ signaling, and mTOR signaling. In summary, SFN elevated muscle fibers size and reduced TG and TC content of in LD muscle by modulating protein and lipid metabolism-related signaling pathways.

The Immunomodulatory Effects of Sulforaphane in Exercise-Induced Inflammation and Oxidative Stress: A Prospective Nutraceutical

Sulforaphane (SFN) is a promising molecule for developing phytopharmaceuticals due to its potential antioxidative and anti-inflammatory effects. A plethora of research conducted in vivo and in vitro reported the beneficial effects of SFN intervention and the underlying cellular mechanisms. Since SFN is a newly identified nutraceutical in sports nutrition, only some human studies have been conducted to reflect the effects of SFN intervention in exercise-induced inflammation and oxidative stress. In this review, we briefly discussed the effects of SFN on exercise-induced inflammation and oxidative stress. We discussed human and animal studies that are related to exercise intervention and mentioned the underlying cellular signaling mechanisms. Since SFN could be used as a potential therapeutic agent, we mentioned briefly its synergistic attributes with other potential nutraceuticals that are associated with acute and chronic inflammatory conditions. Given its health-promoting effects, SFN could be a prospective nutraceutical at the forefront of sports nutrition.

The Molecular Mechanisms of Fuel Utilization during Exercise

Exercise is widely recognized for its positive impact on human health and well-being. The process of utilizing substrates in skeletal muscle during exercise is intricate and governed by complex mechanisms. Carbohydrates and lipids serve as the primary fuel sources for skeletal muscle during exercise. It is now understood that fuel selection during exercise is not solely determined by physical activity itself but is also influenced by the overall metabolic state of the body. The balance between lipid and carbohydrate utilization significantly affects exercise capacity, including endurance, fatigue, and overall performance. Therefore, comprehensively understanding the regulation of substrate utilization during exercise is of utmost importance. The aim of this review is to provide an extensive overview of the current knowledge regarding the pathways involved in the regulation of substrate utilization during exercise. By synthesizing existing research, we can gain a holistic perspective on the intricate relationship between exercise, metabolism, and fuel selection. This advanced understanding has the potential to drive advancements in the field of exercise science and contribute to the development of personalized exercise strategies for individuals looking to optimize their performance and overall health.

Unravelling of molecular biomarkers in synaptic plasticity of Alzheimer's disease: Critical role of the restoration of neuronal circuits

Learning and memory storage are the fundamental activities of the brain. Aberrant expression of synaptic molecular markers has been linked to memory impairment in AD. Aging is one of the risk factors linked to gradual memory loss. It is estimated that approximately 13 million people worldwide will have AD by 2050. A massive amount of oxidative stress is kept under control by a complex network of antioxidants, which occasionally fails and results in neuronal oxidative stress. Increasing evidence suggests that ROS may affect many pathological aspects of AD, including Aβ accumulation, tau hyperphosphorylation, synaptic plasticity, and mitochondrial dysfunction, which may collectively result in neurodegeneration in the brain. Further investigation into the relationship between oxidative stress and AD may provide an avenue for effective preservation and pharmacological treatment of this neurodegenerative disease. In this review, we briefly summarize the cellular mechanism underlying Aβ induced synaptic dysfunction. Since oxidative stress is common in the elderly and may contribute to the pathogenesis of AD, we also shed light on the role of antioxidant and inflammatory pathways in oxidative stress adaptation, which has a potential therapeutic target in neurodegenerative diseases.

Glucosinolate-rich broccoli sprouts protect against oxidative stress and improve adaptations to intense exercise training

Oxidative stress plays a vital role for the adaptive responses to physical training. However, excessive oxidative stress can precipitate cellular damage, necessitating protective mechanisms to mitigate this effect. Glucosinolates, found predominantly in cruciferous vegetables, can be converted into isothiocyanates, known for their antioxidative properties. These compounds activate crucial antioxidant defence pathways and support mitochondrial function and protein integrity under oxidative stress, in both Nrf2-dependent and independent manners. We here administered glucosinolate-rich broccoli sprouts (GRS), in a randomized double-blinded cross-over fashion to 9 healthy subjects in combination with daily intense exercise training for 7 days. We found that exercise in combination with GRS significantly decreased the levels of carbonylated proteins in skeletal muscle and the release of myeloperoxidase into blood. Moreover, it lowered lactate accumulation during submaximal exercise, and attenuated the severe nocturnal hypoglycaemic episodes seen during the placebo condition. Furthermore, GRS in combination with exercise improved physical performance, which was unchanged in the placebo condition.

Moderate exercise-induced dynamics on key sepsis-associated signaling pathways in the liver

BACKGROUND

There is a clear relationship between quantitative measures of fitness (e.g., VO₂ max) and outcomes after surgical procedures. Whether or not fitness is a modifiable risk factor and what underlying biological processes drive these changes are not known. The purpose of this study was to evaluate the moderate exercise training effect on sepsis outcomes (survival) as well as the hepatic biological response. We chose to study the liver because it plays a central role in the regulation of immune defense during systemic infection and receives blood flow directly from the origin of infection (gut) in the cecal ligation and puncture (CLP) model.

METHODS

We randomized 50 male (♂) and female (♀) Sprague-Dawley rats (10 weeks, 340 g) to 3 weeks of treadmill exercise training, performed CLP to induce polymicrobial "sepsis," and monitored survival for five days (Part I). In parallel (Part II), we randomized 60 rats to control/sedentary (G1), exercise (G2), exercise + sham surgery (G3), CLP/sepsis (G4), exercise + CLP [12 h (G5) and 24 h (G6)], euthanized at 12 or 24 h, and explored molecular pathways related to exercise and sepsis survival in hepatic tissue and serum.

RESULTS

Three weeks of exercise training significantly increased rat survival following CLP (polymicrobial sepsis). CLP increased inflammatory markers (e.g., TNF-a, IL-6), which were attenuated by exercise. Sepsis suppressed the SOD and Nrf2 expression, and exercise before sepsis restored SOD and Nrf2 levels near the baseline. CLP led to increased HIF1a expression and oxidative and nitrosative stress, the latter of which were attenuated by exercise. Haptoglobin expression levels were increased in CLP animals, which was significantly amplified in exercise + CLP (24 h) rats.

CONCLUSIONS

Moderate exercise training (3 weeks) increased the survival in rats exposed to CLP, which was associated with less inflammation, less oxidative and nitrosative stress, and activation of antioxidant defense pathways.

Milk Fat Globule Membrane Relieves Fatigue via Regulation of Oxidative Stress and Gut Microbiota in BALB/c Mice

Milk fat globule membranes (MFGMs) are complex structures that incorporate bioactive proteins and lipids to assist in infant development. However, the antifatigue and antioxidant potentials of MFGM have not been investigated. In this study, repeated force swimming measured fatigue in male BALB/c mice fed MFGM and saline for 18 weeks. The MFGM supplementation increased the time to exhaustion by 42.7% at 6 weeks and 30.6% at 14 weeks (p < 0.05). Fatigue and injury-related biomarkers, including blood glucose, lactic acid, and lactate dehydrogenase, were ameliorated after free swimming (p < 0.05). The activity of antioxidant enzymes in blood serum increased at 18 weeks, while malondialdehyde (MDA) content decreased by 45.0% after the MFGM supplementation (p < 0.05). The Pearson correlation analysis showed a high correlation between fatigue-related indices and antioxidant levels. The increased protein expression of hepatic Nrf2 reduced the protein expression of Caspase-3 in the gastrocnemius muscle (p < 0.05). Moreover, the MFGM supplementation increased the relative abundance of Bacteroides, Butyricimonas, and Anaerostipes. Our results demonstrate that MFGM may maintain redox homeostasis to relieve fatigue, suggesting the potential application of MFGM as an antifatigue and antioxidant dietary supplement.

Endogenous and Exogenous Antioxidants in Skeletal Muscle Fatigue Development during Exercise

Muscle fatigue is defined as a decrease in maximal force or power generated in response to contractile activity, and it is a risk factor for the development of musculoskeletal injuries. One of the many stressors imposed on skeletal muscle through exercise is the increased production of reactive oxygen species (ROS) and reactive nitrogen species (RNS), which intensifies as a function of exercise intensity and duration. Exposure to ROS/RNS can affect Na⁺/K⁺-ATPase activity, intramyofibrillar calcium turnover and sensitivity, and actin-myosin kinetics to reduce muscle force production. On the other hand, low ROS/RNS concentrations can likely upregulate an array of cellular adaptative responses related to mitochondrial biogenesis, glucose transport and muscle hypertrophy. Consequently, growing evidence suggests that exogenous antioxidant supplementation might hamper exercise-engendering upregulation in the signaling pathways of mitogen-activated protein kinases (MAPKs), peroxisome-proliferator activated co-activator 1α (PGC-1α), or mammalian target of rapamycin (mTOR). Ultimately, both high (exercise-induced) and low (antioxidant intervention) ROS concentrations can trigger beneficial responses as long as they do not override the threshold range for redox balance. The mechanisms underlying the two faces of ROS/RNS in exercise, as well as the role of antioxidants in muscle fatigue, are presented in detail in this review.

Role of Nrf2 and exercise in alleviating COPD-induced skeletal muscle dysfunction

Chronic obstructive pulmonary disease (COPD) is a complex chronic respiratory disease with cumulative impacts on multiple systems, exhibiting significant extrapulmonary impacts, and posing a serious public health problem. Skeletal muscle dysfunction is one of the most pronounced extrapulmonary effects in patients with COPD, which severely affects patient prognosis and mortality primarily through reduced productivity resulting from muscle structural and functional alterations. Although the detailed pathogenesis of COPD has not been fully determined, some researchers agree that oxidative stress plays a significant role. Oxidative stress not only catalyzes the progression of pulmonary symptoms but also drives the development of skeletal muscle dysfunction. Nuclear factor erythroid 2-related factor 2 (Nrf2), is a key transcription factor that regulates the antioxidant response and plays an enormous role in combating oxidative stress. In this review, we have summarized current research on oxidative stress damage to COPD skeletal muscle and analyzed the role of Nrf2 in improving skeletal muscle dysfunction in COPD through exercise. The results suggest that oxidative stress drives the occurrence and development of skeletal muscle dysfunction in COPD. Exercise may improve skeletal muscle dysfunction in patients with COPD by promoting the dissociation of Kelch-like ECH-associated protein 1 (Keap1) and Nrf2, inducing sequestosome1(p62) phosphorylation to bind with Keap1 competitively leading to Nrf2 stabilization and improving dynamin-related protein 1-dependent mitochondrial fission. Nrf2 may be a key target for exercise anti-oxidative stress to alleviate skeletal muscle dysfunction in COPD.

Phytochemicals and modulation of exercise-induced oxidative stress: a novel overview of antioxidants

The practice of physical exercise induces a series of physiological changes in the body at different levels, either acutely or chronically. During exercise, the increase in oxygen consumption promotes the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS), which are necessary to maintain homeostasis. ROS/RNS activate cellular signaling pathways, such as the antioxidant cytoprotective systems, inflammation, and cell proliferation, which are crucial for cell survival. However, in exhaustive-extended physical exercise, workloads can exceed the endogenous antioxidant defenses, which may be related to impairment of muscle contraction, fatigue, and a decrease in athletic performance. This review addresses the role of some antioxidants from plant-derived extracts called phytochemicals that can mediate the response to oxidative stress induced by physical exercise by activating signaling pathways, such as Nrf2/Keap1/ARE, responsible for the endogenous antioxidant response and possibly having an impact on sports performance.

Phytochemicals in Skeletal Muscle Health: Effects of Curcumin (from Curcuma longa Linn) and Sulforaphane (from Brassicaceae) on Muscle Function, Recovery and Therapy of Muscle Atrophy

The mobility of the human body depends on, among other things, muscle health, which can be affected by several situations, such as aging, increased oxidative stress, malnutrition, cancer, and the lack or excess of physical exercise, among others. Genetic, metabolic, hormonal, and nutritional factors are intricately involved in maintaining the balance that allows proper muscle function and fiber recovery; therefore, the breakdown of the balance among these elements can trigger muscle atrophy. The study from the nutrigenomic perspective of nutritional factors has drawn wide attention recently; one of these is the use of certain compounds derived from foods and plants known as phytochemicals, to which various biological activities have been described and attributed in terms of benefiting health in many respects. This work addresses the effect that the phytochemicals curcumin from Curcuma longa Linn and sulforaphane from Brassicaceae species have shown to exert on muscle function, recovery, and the prevention of muscle atrophy, and describes the impact on muscle health in general. In the same manner, there are future perspectives in research on novel compounds as potential agents in the prevention or treatment of medical conditions that affect muscle health.

Dual-Scale Porous Composite for Tactile Sensor with High Sensitivity over an Ultrawide Sensing Range

Porous structures have been utilized in tactile sensors to improve sensitivity owing to their excellent deformability. Recently, tactile sensors using porous structures have been used in practical applications, such as bio-signal monitoring. However, highly sensitive responses are limited to the low-pressure range, and their sensitivity significantly decreases in a higher-pressure range. Several approaches for developing tactile sensors with high sensitivity overing a wide pressure range have been proposed; however, achieving high sensitivity and wide sensing range remains a crucial challenge. This report presents a carbon nanotube (CNT)-coated CNT-polydimethylsiloxane (PDMS) composite having dual-scale pores for tactile sensors with high sensitivity over a wide pressure range. The porous polymer frame formed with dense pores of dual sizes facilitates the closure of large and small pores at low and high pressures, respectively. This results in an apparent increase in the number of contact points between the CNT-CNT at the pores even under a wide pressure range. Furthermore, the piezoresistivity of the CNT-PDMS composite contributes to achieving a high sensitivity of the tactile sensor over a wide pressure range. Based on these mechanisms, various human movements over a broad pressure spectrum are monitored to investigate the practical usefulness of the sensor.

The mechanism of Yinchenhao decoction in treating obstructive-jaundice-induced liver injury based on Nrf2 signaling pathway

BACKGROUND

Obstructive jaundice (OJ) is caused by bile excretion disorder after partial or complete bile duct obstruction. It may cause liver injury through various mechanisms. Traditional Chinese medicine (TCM) has a lot of advantages in treating OJ. The recovery of liver function can be accelerated by combining Chinese medicine treatment with existing clinical practice. Yinchenhao decoction (YCHD), a TCM formula, has been used to treat jaundice. Although much progress has been made in recent years in understanding the mechanism of YCHD in treating OJ-induced liver injury, it is still not clear.

AIM

To investigate chemical components of YCHD that are effective in the treatment of OJ and predict the mechanism of YCHD.

METHODS

The active components and putative targets of YCHD were predicted using a network pharmacology approach. Gene Ontology biological process and Kyoto Encyclopedia of Genes and Genomes path enrichment analysis were carried out by cluster profile. We predicted the biological processes, possible targets, and associated signaling pathways that YCHD may involve in the treatment of OJ. Thirty male Sprague–Dawley rats were randomly divided into three groups, each consisting of 10 rats: the sham group (Group S), the OJ model group (Group M), and the YCHD-treated group (Group Y). The sham group only received laparotomy. The OJ model was established by ligating the common bile duct twice in Groups M and Y. For 1 wk, rats in Group Y were given a gavage of YCHD (3.6 mL/kg) twice daily, whereas rats in Groups S and M were given the same amount of physiological saline after intragastric administration daily. After 7 d, all rats were killed, and the liver and blood samples were collected for histopathological and biochemical examinations. Total bilirubin (TBIL), direct bilirubin (DBIL), alanine aminotransferase (ALT), and aspartate transaminase (AST) levels in the blood samples were detected. The gene expression levels of inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS), and the nucleus positive rate of NF-E2 related factor 2 (Nrf2) protein were measured. Western blot analyses were used to detect the protein and gene expression levels of Nrf2, Kelch-like ECH-associated protein 1, NAD(P)H quinone dehydrogenase 1 (NQO1), and glutathione-S-transferase (GST) in the liver tissues. One-way analysis of variance was used to evaluate the statistical differences using the statistical package for the social sciences 23.0 software. Intergroup comparisons were followed by the least significant difference test and Dunnett’s test.

RESULTS

The effects of YCHD on OJ involve biological processes such as DNA transcription factor binding, RNA polymerase II specific regulation, DNA binding transcriptional activator activity, and nuclear receptor activity. The protective effects of YCHD against OJ were closely related to 20 pathways, including the hepatitis-B, the mitogen-activated protein kinase, the phosphatidylinositol 3-kinase/protein kinase B, and tumor necrosis factor signaling pathways. YCHD alleviated the swelling and necrosis of hepatocytes. Following YCHD treatment, the serum levels of TBIL (176.39 ± 17.03 μmol/L vs 132.23 ± 13.88 μmol/L, P < 0.01), DBIL (141.41 ± 14.66 μmol/L vs 106.43 ± 10.88 μmol/L, P < 0.01), ALT (332.07 ± 34.34 U/L vs 269.97 ± 24.78 U/L, P < 0.05), and AST (411.44 ± 47.64 U/L vs 305.47 ± 29.36 U/L, P < 0.01) decreased. YCHD promoted the translocation of Nrf2 into the nucleus (12.78 ± 0.99 % vs 60.77 ± 1.90 %, P < 0.001). After YCHD treatment, we found a decrease in iNOS (0.30 ± 0.02 vs 0.20 ± 0.02, P < 0.001) and an increase in eNOS (0.18 ± 0.02 vs 0.32 ± 0.02, P < 0.001). Meanwhile, in OJ rats, YCHD increased the expressions of Nrf2 (0.57 ± 0.03 vs 1.18 ± 0.10, P < 0.001), NQO1 (0.13 ± 0.09 vs 1.19 ± 0.07, P < 0.001), and GST (0.12 ± 0.02 vs 0.50 ± 0.05, P < 0.001), implying that the potential mechanism of YCHD against OJ-induced liver injury was the upregulation of the Nrf2 signaling pathway.

CONCLUSION

OJ-induced liver injury is associated with the Nrf2 signaling pathway. YCHD can reduce liver injury and oxidative damage by upregulating the Nrf2 pathway.

Effects of different-intensity exercise and creatine supplementation on mitochondrial biogenesis and redox status in mice

Objectives

Dietary supplementation combined with exercise may potentiate the beneficial effects of exercise by reducing exercise-induced oxidative stress and improving mitochondrial quality and capacity. In this study, the effects of creatine monohydrate (CrM) supplementation with low and high-intensity exercise on mitochondrial biogenesis regulators, Nrf2 anti-oxidant signaling pathway and muscle damage levels were investigated.

Materials and Methods

Balb/c male mice were divided into six experimental groups: control, control+CrM, high-intensity exercise, high-intensity exercise+CrM, low-intensity exercise, and low-intensity exercise+CrM. Mice were given CrM supplementation and at the same time, low and high-intensity exercise was applied to the groups on the treadmill at 30min/5day/8week. Then, mitochondrial biogenesis marker (PGC-1α, NRF-1, TFAM), Nrf2 and HO-1 protein expressions, total oxidant-anti-oxidant status level, and histopathological changes were investigated in serum and muscle tissue.

Results

Exercise intensity and CrM supplementation were found to be effective factors in mitochondrial biogenesis induction via the PGC-1α signaling pathway. Nrf2 and HO-1 protein levels increased with exercise intensity, and this result was directly related to serum oxidative stress markers. In addition, CrM supplementation was effective in reducing exercise-induced muscle damage.

Conclusion

This combination induced skeletal muscle adaptations, including mitochondrial biogenesis and enhanced anti-oxidant reserves. This synergistic effect of dietary supplementation with low-intensity exercise may be valuable as a complement to treatment, especially in diseases caused by mitochondrial dysfunction.

Pharmaceutical Potential of High-Altitude Plants for Fatigue-Related Disorders: A Review

Natural plants from plateaus have been the richest source of secondary metabolites extensively used in traditional and modern health care systems. They were submitted to years of natural selection, co-evolved within that habitat, and show significant anti-fatigue-related pharmacological effects. However, currently, no review on high-altitude plants with anti-fatigue related properties has been published yet. This study summarized several Chinese traditional high-altitude plants, including Rhodiola rosea L., Crocus sativus L., Lepidium meyenii W., Hippophaerhamnoides L., which are widely used in the Qinghai–Tibet Plateau and surrounding mountains, as well as herbal markets in the plains. Based on phytopharmacology studies, deeper questions can be further revealed regarding how these plants regulate fatigue and related mental or physical disease conditions. Many active derivatives in high-altitude medical plants show therapeutic potential for the management of fatigue and related disorders. Therefore, high-altitude plants significantly relieve central or peripheral fatigue by acting as neuroprotective agents, energy supplements, metabolism regulators, antioxidant, and inflammatory response inhibitors. Their applications on the highland or flatland and prospects in natural medicine are further forecast, which may open treatments to reduce or prevent fatigue-related disorders in populations with sub-optimal health.

Sulforaphane reduces obesity by reversing leptin resistance

The ascending prevalence of obesity in recent decades is commonly associated with soaring morbidity and mortality rates, resulting in increased health-care costs and decreased quality of life. A systemic state of stress characterized by low-grade inflammation and pathological formation of reactive oxygen species (ROS) usually manifests in obesity. The transcription factor nuclear factor erythroid-derived 2-like 2 (NRF2) is the master regulator of the redox homeostasis and plays a critical role in the resolution of inflammation. Here, we show that the natural isothiocyanate and potent NRF2 activator sulforaphane reverses diet-induced obesity through a predominantly, but not exclusively, NRF2-dependent mechanism that requires a functional leptin receptor signaling and hyperleptinemia. Sulforaphane does not reduce the body weight or food intake of lean mice but induces an anorectic response when coadministered with exogenous leptin. Leptin-deficient Lep^ob/ob mice and leptin receptor mutant Lepr^db/db mice display resistance to the weight-reducing effect of sulforaphane, supporting the conclusion that the antiobesity effect of sulforaphane requires functional leptin receptor signaling. Furthermore, our results suggest the skeletal muscle as the most notable site of action of sulforaphane whose peripheral NRF2 action signals to alleviate leptin resistance. Transcriptional profiling of six major metabolically relevant tissues highlights that sulforaphane suppresses fatty acid synthesis while promoting ribosome biogenesis, reducing ROS accumulation, and resolving inflammation, therefore representing a unique transcriptional program that leads to protection from obesity. Our findings argue for clinical evaluation of sulforaphane for weight loss and obesity-associated metabolic disorders.

Role for Plant-Derived Antioxidants in Attenuating Cancer Cachexia

Cancer cachexia is the progressive muscle wasting and weakness experienced by many cancer patients. It can compromise the response to gold standard cancer therapies, impair functional capacity and reduce overall quality of life. Cancer cachexia accounts for nearly one-third of all cancer-related deaths and has no effective treatment. The pathogenesis of cancer cachexia and its progression is multifactorial and includes increased oxidative stress derived from both the tumor and the host immune response. Antioxidants have therapeutic potential to attenuate cancer-related muscle loss, with polyphenols, a group of plant-derived antioxidants, being the most widely investigated. This review describes the potential of these plant-derived antioxidants for treating cancer cachexia.

Investigating the Potential for Sulforaphane to Attenuate Gastrointestinal Dysfunction in mdx Dystrophic Mice

Gastrointestinal (GI) dysfunction is an important, yet understudied condition associated with Duchenne muscular dystrophy (DMD), with patients reporting bloating, diarrhea, and general discomfort, contributing to a reduced quality of life. In the mdx mouse, the most commonly used mouse model of DMD, studies have confirmed GI dysfunction (reported as altered contractility and GI transit through the small and large intestine), associated with increased local and systemic inflammation. Sulforaphane (SFN) is a natural isothiocyanate with anti-inflammatory and anti-oxidative properties via its activation of Nrf2 signalling that has been shown to improve aspects of the skeletal muscle pathology in dystrophic mice. Whether SFN can similarly improve GI function in muscular dystrophy was unknown. Video imaging and spatiotemporal mapping to assess gastrointestinal contractions in isolated colon preparations from mdx and C57BL/10 mice revealed that SFN reduced contraction frequency when administered ex vivo, demonstrating its therapeutic potential to improve GI function in DMD. To confirm this in vivo, four-week-old male C57BL/10 and mdx mice received vehicle (2% DMSO/corn oil) or SFN (2 mg/kg in 2% DMSO/corn oil) via daily oral gavage five days/week for 4 weeks. SFN administration reduced fibrosis in the diaphragm of mdx mice but did not affect other pathological markers. Gene and protein analysis revealed no change in Nrf2 protein expression or activation of Nrf2 signalling after SFN administration and oral SFN supplementation did not improve GI function in mdx mice. Although ex vivo studies demonstrate SFN’s therapeutic potential for reducing colon contractions, in vivo studies should investigate higher doses and/or alternate routes of administration to confirm SFN’s potential to improve GI function in DMD.

Skeletal muscle NOX4 is required for adaptive responses that prevent insulin resistance

Reactive oxygen species (ROS) generated during exercise are considered integral for the health-promoting effects of exercise. However, the precise mechanisms by which exercise and ROS promote metabolic health remain unclear. Here, we demonstrate that skeletal muscle NADPH oxidase 4 (NOX4), which is induced after exercise, facilitates ROS-mediated adaptive responses that promote muscle function, maintain redox balance, and prevent the development of insulin resistance. Conversely, reductions in skeletal muscle NOX4 in aging and obesity contribute to the development of insulin resistance. NOX4 deletion in skeletal muscle compromised exercise capacity and antioxidant defense and promoted oxidative stress and insulin resistance in aging and obesity. The abrogated adaptive mechanisms, oxidative stress, and insulin resistance could be corrected by deleting the H₂O₂-detoxifying enzyme GPX-1 or by treating mice with an agonist of NFE2L2, the master regulator of antioxidant defense. These findings causally link NOX4-derived ROS in skeletal muscle with adaptive responses that promote muscle function and insulin sensitivity.

A Multi-Ingredient Formula Ameliorates Exercise-Induced Fatigue by Changing Metabolic Pathways and Increasing Antioxidant Capacity in Mice

Multiple mechanisms are involved in exercise-induced fatigue, including energy depletion, metabolite accumulation, and oxidative stress, etc. The mechanistic findings provide a rationale for a multi-targeted approach to exercise-induced fatigue management. This study created a multi-ingredient formula mixed with valine, isoleucine, leucine, β-alanine, creatine, l-carnitine, quercetin, and betaine, based on the functional characteristics of these agents, and evaluated the preventive effect of this mechanism-based formula on exercise-induced fatigue. Results showed that the 7-d formula supplement significantly increased the running duration time of mice by 14% and the distance by 20% in an exhaustive treadmill test, indicating that the formula could delay fatigue appearance and improve exercise performance. Mechanistically, the formula enhanced fatty acid oxidation and spared liver glycogen by regulating the fat/glucose metabolism-related signaling pathways, including phospho-adenosine monophosphate-activated protein kinase α (p-AMPKα), phospho-acetyl CoA carboxylase (p-ACC), carnitine palmitoyl-transferase 1B (CPT1B), fatty acid translocase (CD36), and glucose transporter type 4 (GLUT4), and increased antioxidant capacity. The findings suggested that the formula tested in this study effectively ameliorated exercise-induced fatigue by targeting multi-signaling pathways, showing promise as a regimen to fight exercise-induced fatigue.

Effect of a sulforaphane supplement on muscle soreness and damage induced by eccentric exercise in young adults: A pilot study

OBJECTIVE

Excessive exercise increases the production of reactive oxygen species in skeletal muscles. Sulforaphane activates nuclear factor erythroid 2-related factor 2 (Nrf2) and induces a protective effect against oxidative stress. In a recent report, sulforaphane intake suppressed exercise-induced oxidative stress and muscle damage in mice. However, the effect of sulforaphane intake on delayed onset muscle soreness after eccentric exercise in humans is unknown. We evaluated the effect of sulforaphane supplement intake in humans regarding the delayed onset muscle soreness (DOMS) after eccentric exercise.

RESEARCH METHODS & PROCEDURES

To determine the duration of sulforaphane supplementation, continuous blood sampling was performed and NQO1 mRNA expression levels were analyzed. Sixteen young men were randomly divided into sulforaphane and control groups. The sulforaphane group received sulforaphane supplements. Each group performed six set of five eccentric exercise with the nondominant arm in elbow flexion with 70% maximum voluntary contraction. We assessed muscle soreness in the biceps using the visual analog scale, range of motion (ROM), muscle damage markers, and oxidative stress marker (malondialdehyde; MDA).

RESULTS

Sulforaphane supplement intake for 2 weeks increased NQO1 mRNA expression in peripheral blood mononuclear cells (PBMCs). Muscle soreness on palpation and ROM were significantly lower 2 days after exercise in the sulforaphane group compared with the control group. Serum MDA showed significantly lower levels 2 days after exercise in the sulforaphane group compared with the control group.

CONCLUSION

Our findings suggest that sulforaphane intake from 2 weeks before to 4 days after the exercise increased NQO1, a target gene of Nrf2, and suppressed DOMS after 2 days of eccentric exercise.

Oxidative Stress, Mitochondrial Function and Adaptation to Exercise: New Perspectives in Nutrition

Cells have the ability to adapt to stressful environments as a part of their evolution. Physical exercise induces an increase of a demand for energy that must be met by mitochondria as the main (ATP) provider. However, this process leads to the increase of free radicals and the so-called reactive oxygen species (ROS), which are necessary for the maintenance of cell signaling and homeostasis. In addition, mitochondrial biogenesis is influenced by exercise in continuous crosstalk between the mitochondria and the nuclear genome. Excessive workloads may induce severe mitochondrial stress, resulting in oxidative damage. In this regard, the objective of this work was to provide a general overview of the molecular mechanisms involved in mitochondrial adaptation during exercise and to understand if some nutrients such as antioxidants may be implicated in blunt adaptation and/or an impact on the performance of exercise by different means.

18β-glycyrrhetinic acid improves high-intensity exercise performance by promoting glucose-dependent energy production and inhibiting oxidative stress in mice

It has been shown that 18β-glycyrrhetinic acid (18β-GA), the main bioactive compound of licorice, can modulate oxidative stress and metabolic processes in liver and skin. Given the critical role of oxidative stress and energy metabolism in exercise-induced fatigue, we hypothesized that 18β-GA could exert an ergogenic action by inhibiting excess reactive oxygen species (ROS) induction and promoting energy production in muscles. Mice were gavage-fed with 18β-GA for four consecutive days. Running ability was assessed based on the exhaustive treadmill test with high- and moderate-intensity. Western blot analysis, enzyme-linked immunosorbent assay, and immunofluorescence staining were used to measure the changes of muscle fatigue-related markers, oxidative stress status, and energy metabolism in response to 18β-GA exposure. Treatment with 18β-GA significantly increased the exhaustive running distance (~37%) in the high-intensity exercise, but not in the moderate-intensity exercise. Mechanistically, reduction of oxidative stress and induction of antioxidants (SOD, CAT, and GSH) by 18β-GA were observed. Moreover, 18β-GA treatment caused an improved preservation of muscle glycogen (12%), which was associated with upregulation of glucose transporter 4 (GLUT4) (91%) and increased insulin level (17%). The findings of the present study clearly suggest that 18β-GA holds excellent potential as a novel bioactive agent against high-intensity exercise-induced fatigue.

The Role of Nrf2 in Skeletal Muscle on Exercise Capacity

Nuclear factor erythroid 2-related factor 2 Nfe2l2 (Nrf2) is believed to play a crucial role in protecting cells against oxidative stress. In addition to its primary function of maintaining redox homeostasis, there is emerging evidence that Nrf2 is also involved in energy metabolism. In this review, we briefly discuss the role of Nrf2 in skeletal muscle metabolism from the perspective of exercise physiology. This article is part of a special issue “Mitochondrial Function, Reactive Oxygen/Nitrogen Species and Skeletal Muscle” edited by Håkan Westerblad and Takashi Yamada.

The Effects of Aerobic-Resistance Training and Broccoli Supplementation on Plasma Dectin-1 and Insulin Resistance in Males with Type 2 Diabetes

Background: This study aimed to evaluate the effects of a combination of aerobic-resistance training (CARET) and broccoli supplementation on dectin-1 levels and insulin resistance in men with type 2 diabetes mellitus (T2D). Methods: Forty-four males with T2D were randomly allocated to four groups (n = 11 each group): CARET + broccoli supplement (TS), CARET + placebo (TP), control + broccoli supplement (S), and control + placebo (CP). CARET was performed three days per week for 12 weeks. TS and S groups received 10 g of broccoli supplement per day for 12 weeks. All variables were assessed at baseline and 12 weeks. Results: Plasma dectin-1 levels were decreased in TS and TP groups compared with the CP group (p < 0.05). Cardiometabolic risk factors showed significant reductions in TP and TS groups compared to S and CP groups (p < 0.05). Conclusion: The combination of CARET and broccoli supplementation produced the largest improvements in insulin resistance and dectin-1 and other complications of T2D.

Nuclear factor E2-related factor 2 (NRF2) deficiency accelerates fast fibre type transition in soleus muscle during space flight

Microgravity induces skeletal muscle atrophy, particularly in the soleus muscle, which is predominantly composed of slow-twitch myofibre (type I) and is sensitive to disuse. Muscle atrophy is commonly known to be associated with increased production of reactive oxygen species. However, the role of NRF2, a master regulator of antioxidative response, in skeletal muscle plasticity during microgravity-induced atrophy, is not known. To investigate the role of NRF2 in skeletal muscle within a microgravity environment, wild-type and Nrf2-knockout (KO) mice were housed in the International Space Station for 31 days. Gene expression and histological analyses demonstrated that, under microgravity conditions, the transition of type I (oxidative) muscle fibres to type IIa (glycolytic) was accelerated in Nrf2-KO mice without affecting skeletal muscle mass. Therefore, our results suggest that NRF2 affects myofibre type transition during space flight.

Mechanisms of Physical Fatigue and its Applications in Nutritional Interventions

Physical fatigue during exercise can be defined as an impairment of physical performance. Multiple factors have been found contributing to physical fatigue, including neurotransmitter-mediated defense action, insufficient energy supply, and induction of oxidative stress. These mechanistic findings provide a sound theoretical rationale for nutritional intervention since most of these factors can be modulated by nutrient supplementation. In this review, we summarize the current evidence regarding the functional role of nutrients supplementation in managing physical performance and propose the issues that need to be addressed for better utilization of nutritional supplementation approach to improve physical performance.

Materials, Actuators, and Sensors for Soft Bioinspired Robots

Biological systems can perform complex tasks with high compliance levels. This makes them a great source of inspiration for soft robotics. Indeed, the union of these fields has brought about bioinspired soft robotics, with hundreds of publications on novel research each year. This review aims to survey fundamental advances in bioinspired soft actuators and sensors with a focus on the progress between 2017 and 2020, providing a primer for the materials used in their design.

Skeletal muscle-specific Keap1 disruption modulates fatty acid utilization and enhances exercise capacity in female mice

Skeletal muscle health is important for the prevention of various age-related diseases. The loss of skeletal muscle mass, which is known as sarcopenia, underlies physical disability, poor quality of life and chronic diseases in elderly people. The transcription factor NRF2 plays important roles in the regulation of the cellular defense against oxidative stress, as well as the metabolism and mitochondrial activity. To determine the contribution of skeletal muscle NRF2 to exercise capacity, we conducted skeletal muscle-specific inhibition of KEAP1, which is a negative regulator of NRF2, and examined the cell-autonomous and non-cell-autonomous effects of NRF2 pathway activation in skeletal muscles. We found that NRF2 activation in skeletal muscles increased slow oxidative muscle fiber type and improved exercise endurance capacity in female mice. We also observed that female mice with NRF2 pathway activation in their skeletal muscles exhibited enhanced exercise-induced mobilization and β-oxidation of fatty acids. These results indicate that NRF2 activation in skeletal muscles promotes communication with adipose tissues via humoral and/or neuronal signaling and facilitates the utilization of fatty acids as an energy source, resulting in increased mitochondrial activity and efficient energy production during exercise, which leads to improved exercise endurance.

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Systemic Keap1 knockdown enhances exercise endurance capacity in mice.

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Keap1 deficiency in skeletal muscle activates NRF2 pathway.

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Keap1 deficiency in skeletal muscle enhances endurance capacity in female mice.

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Keap1 deficiency in skeletal muscle promotes exercise-induced fatty acid utilization.

Physical activity and exercise: Strategies to manage frailty

Frailty, a consequence of the interaction of the aging process and certain chronic diseases, compromises functional outcomes in the elderly and substantially increases their risk for developing disabilities and other adverse outcomes. Frailty follows from the combination of several impaired physiological mechanisms affecting multiple organs and systems. And, though frailty and sarcopenia are related, they are two different conditions. Thus, strategies to preserve or improve functional status should consider systemic function in addition to muscle conditioning. Physical activity/exercise is considered one of the main strategies to counteract frailty-related physical impairment in the elderly. Exercise reduces age-related oxidative damage and chronic inflammation, increases autophagy, and improves mitochondrial function, myokine profile, insulin-like growth factor-1 (IGF-1) signaling pathway, and insulin sensitivity. Exercise interventions target resistance (strength and power), aerobic, balance, and flexibility work. Each type improves different aspects of physical functioning, though they could be combined according to need and prescribed as a multicomponent intervention. Therefore, exercise intervention programs should be prescribed based on an individual's physical functioning and adapted to the ensuing response.

The Integrative Role of Sulforaphane in Preventing Inflammation, Oxidative Stress and Fatigue: A Review of a Potential Protective Phytochemical

Cruciferous vegetables hold a myriad of bioactive molecules that are renowned for possessing unique medicinal benefits. Sulforaphane (SFN) is one of the potential nutraceuticals contained within cruciferous vegetables that is useful for improving health and diseased conditions. The objective of this review is to discuss the mechanistic role for SFN in preventing oxidative stress, fatigue, and inflammation. Direct and indirect research evidence is reported to identify the nontoxic dose of SFN for human trials, and effectiveness of SFN to attenuate inflammation and/or oxidative stress. SFN treatment modulates redox balance via activating redox regulator nuclear factor E2 factor-related factor (Nrf2). SFN may play a crucial role in altering the Keap1/Nrf2/ARE pathway (an intricate response to many stimuli or stress), which induces Nrf2 target gene activation to reduce oxidative stress. In addition, SFN reduces inflammation by suppressing centrally involved inflammatory regulator nuclear factor-kappa B (NF-κB), which in turn downregulates the expression of proinflammatory cytokines and mediators. Exercise may induce a significant range of fatigue, inflammation, oxidative stress, and/or organ damage due to producing excessive reactive oxygen species (ROS) and inflammatory cytokines. SFN may play an effective role in preventing such damage via inducing phase 2 enzymes, activating the Nrf2/ARE signaling pathway or suppressing nuclear translocation of NF-κB. In this review, we summarize the integrative role of SFN in preventing fatigue, inflammation, and oxidative stress, and briefly introduce the history of cruciferous vegetables and the bioavailability and pharmacokinetics of SFN reported in previous research. To date, very limited research has been conducted on SFN’s effectiveness in improving exercise endurance or performance. Therefore, more research needs to be carried out to determine the effectiveness of SFN in the field of exercise and lifestyle factors.

Characterization and Modulation of Systemic Inflammatory Response to Exhaustive Exercise in Relation to Oxidative Stress

Exhaustive exercise induces systemic inflammatory responses, which are associated with exercise-induced tissue/organ damage, but the sources and triggers are not fully understood. Herein, the basics of inflammatory mediator cytokines and research findings on the effects of exercise on systemic inflammation are introduced. Subsequently, the association between inflammatory responses and tissue damage is examined in exercised and overloaded skeletal muscle and other internal organs. Furthermore, an overview of the interactions between oxidative stress and inflammatory mediator cytokines is provided. Particularly, the transcriptional regulation of redox signaling and pro-inflammatory cytokines is described, as the activation of the master regulatory factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is involved directly or indirectly in controlling pro-inflammatory genes and antioxidant enzymes expression, whilst nuclear factor-kappa B (NF-κB) regulates the pro-inflammatory gene expression. Additionally, preventive countermeasures against the pathogenesis along with the possibility of interventions such as direct and indirect antioxidants and anti-inflammatory agents are described. The aim of this review is to give an overview of studies on the systematic inflammatory responses to exercise, including our own group as well as others. Moreover, the challenges and future directions in understanding the role of exercise and functional foods in relation to inflammation and oxidative stress are discussed.

Anti-fatigue effect of anwulignan via the NRF2 and PGC-1α signaling pathway in mice

OBJECTIVE

To examine the anti-fatigue function of anwulignan from Schisandra and its underlying mechanism.

METHODS

After an excessive fatigue mouse model was created, anwulignan was administered to the mice, and its effect on exercise tolerance was studied by the weight-bearing swimming test, rotarod test, grip strength test, and tail suspension test. The biochemical indicators closely related to fatigue, including blood urea nitrogen (BUN), lactic acid (LD), lactate dehydrogenase (LDH), and creatine kinase (CK) in the serum; liver glycogen (LG) in the liver tissue; muscle glycogen (MG); inorganic phosphate (Pi) and Annexin V in the gastrocnemius; superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities; malondialdehyde (MDA), catalase (CAT), and thiobarbituric acid reactive substances (TBARS); and the 8-hydroxy-2-deoxyguanosine (8-OHdG) and reactive oxygen species (ROS) content in both serum and the gastrocnemius were detected. Morphological changes were also observed. The anti-fatigue-related proteins of the NRF2/ARE, Bcl2, and PGC-1α pathways in the gastrocnemius of the mice were detected by western blot.

RESULTS

Anwulignan significantly increased the exercise tolerance by decreasing BUN, LD, LDH, CK, Pi, MDA, TBARS, 8-OHdG, ROS, and Annexin V levels and increasing LG, MG, SOD, CAT, and GSH-Px levels, significantly upregulated the expression of NRF2 and Bcl2 proteins, which are anti-oxidation and anti-apoptosis regulators, and also activated the p38MAPK-PGC-1α pathway.

CONCLUSION

Anwulignan can increase exercise tolerance and relieve fatigue in an excessive fatigue mouse model. The underlying mechanism may be through its regulatory effect on the NRF2 and PGC-1α signaling pathway. This study will provide scientific data for anwulignan to be developed as a novel and efficient component in anti-oxidant or anti-fatigue health food.

Nrf2 Activation Enhances Muscular MCT1 Expression and Hypoxic Exercise Capacity

INTRODUCTION

Skeletal muscle is the major producing and metabolizing site of lactic acid. A family of monocarboxylate transporter (MCT) proteins, especially MCT1 and MCT4, are involved in the lactate-pyruvate exchange and metabolism. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a pivotal coordinator of antioxidant response and energy metabolism, and has been reported to associate with the physiological functions of the skeletal muscle.

METHODS

In this study, C57BL/6 J mice were administrated with an Nrf2 activator, sulforaphane (SFN) before taking incremental treadmill exercise to exhaustion under hypoxia; then the effects of SFN on exercise endurance and molecular/biochemical makers of the skeletal muscle were evaluated.

RESULTS

The results indicated that SFN pretreatment enhanced the exercise endurance under hypoxia. SFN not only increased the expressions of antioxidant genes and activity of antioxidant enzymes, but also significantly increased the mRNA and protein levels of MCT1 and CD147, but not MCT4. Moreover, the expressions of LDH-B and LDH activity of converting lactate into pyruvate, as well as citrate synthase activity were significantly higher, whereas the LDH activity of converting pyruvate into lactate and blood lactate level were remarkably lower in the SFN-exercise mice than those of the phosphate-buffered saline-exercise group. Furthermore, Atf3Δzip2 (the alternatively spliced isoform of activating transcription factor-3) mRNA was increased by the exercise and further potentiated by SFN.

CONCLUSION

These results show, for the first time, that SFN increases MCT1 expression in the skeletal muscle under acute hypoxic exercise and suggest that Nrf2 activation is a promising strategy to enhance exercise performance under hypoxia.

Protective Effects of Sulforaphane on Exercise-Induced Organ Damage via Inducing Antioxidant Defense Responses

Regular exercise is beneficial to maintain a healthy lifestyle, but the beneficial effects are lost in the case of acute exhaustive exercise; this causes significant inflammation, oxidative stress along with organ damage. Recently, sulforaphane (SFN), an indirect antioxidant, has drawn special attention for its potential protective effect against inflammation and oxidative stress. However, no studies have been performed regarding acute exhaustive exercise-induced organ damage in association with SFN administration. Therefore, the aim of this study was to investigate the effects of SFN on acute exhaustive exercise-induced organ damage and the mechanisms involved. To perform the study, we divided mice into four groups: Control, SFN, exercise, and SFN plus exercise. The SFN group was administered orally (50 mg/kg body wt) 2 h before the running test. We measured plasma levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH), and acute exhaustive exercise significantly increased these biomarkers. In addition, the mRNA expression of pro-inflammatory cytokines, IL-6, IL-1β, and TNF-α, were significantly increased in the liver of exercise group. However, the SFN plus exercise group showed a significant reduction in the expression of cytokines and blood biomarkers of tissue damage or cell death. Furthermore, we measured mRNA expression of Nrf2, heme oxygenase (HO)-1, and antioxidant defense enzymes expression, i.e., superoxide dismutase (SOD1), catalase (CAT), and glutathione peroxidase (GPx1) in the liver. The expression of all these biomarkers was significantly upregulated in the SFN plus exercise group. Collectively, SFN may protect the liver from exhaustive exercise-induced inflammation via inducing antioxidant defense response through the activation of Nrf2/HO-1 signal transduction pathway.

Liver-Metabolizing Genes and Their Relationship to the Performance of Elite Spanish Male Endurance Athletes; a Prospective Transversal Study

Background

The genetic profile that is needed to define an endurance athlete has been studied during recent years. The main objective of this work is to approach for the first time the study of genetic variants in liver-metabolizing genes and their role in endurance performance by comparing the allelic and genotypic frequencies in elite endurance athletes to the non-athlete population.

Methods

Genotypic and allelic frequencies were determined in 123 elite endurance athletes (75 professional road cyclists and 48 endurance elite runners) and 122 male non-athlete subjects (sedentary). Genotyping of cytochrome P450 family 2 subfamily D member 6 (CYP2D6 rs3892097), glutathione-S transferase mu isoform 1 (GSTM1), glutathione S-transferase pi (GSTP rs1695) and glutathione S-transferase theta (GSTT) genes was performed by polymerase chain reaction (PCR). The combination of the polymorphisms for the “optimal” polygenic profile has been quantified using the genotype score (GS).

Results

Statistical differences were found in the genetic distributions between elite endurance athletes and non-athletes in CYP2D6 (p < 0.001) and GSTT (p = 0.014) genes. The binary logistic regression model showed a favourable OR (odds ratio) of being an elite endurance runner against a professional road cyclist (OR: 2.403, 95% CI: 1.213–4.760 (p = 0.002)) in the polymorphisms studied.

Conclusions

Genotypic distribution of liver-metabolizing genes in elite endurance athletes is different to non-athlete subjects, with a favourable gene profile in elite endurance athletes in terms of detoxification capacity.

Hypoxia preconditioning promotes endurance exercise capacity of mice by activating skeletal muscle Nrf2

Elite endurance athletes are used to train under hypoxic/high-altitude conditions, which can elicit certain stress responses in skeletal muscle and helps to improve their physical performance. Nuclear factor erythroid 2-related factor 2 (Nrf2) regulates cellular redox homeostasis and metabolism in skeletal muscle, playing important roles in adaptation to various stresses. In this study, Nrf2 knockout (KO) and wild-type (WT) mice were preconditioned to 48 h of hypoxia exposure (11.2% oxygen), and the effects of hypoxia preconditioning (HP) on exercise capacity and exercise-induced changes of antioxidant status, energetic metabolism, and mitochondrial adaptation in skeletal muscle were evaluated. Nrf2 knockout (KO) and wild-type (WT) mice were exposed to normoxia or hypoxia for 48 h before taking incremental treadmill exercise to exhaustion under hypoxia. The skeletal muscles were collected immediately after the incremental treadmill exercise to evaluate the impacts of HP and Nrf2 on the exercise-induced changes. The results indicate the absence of Nrf2 did not affect exercise capacity, although the mRNA expression of certain muscular genes involved in antioxidant, glycogen and fatty acid catabolism was decreased in Nrf2 KO mice. However, 48-h HP enhanced exercise capacity in WT mice but not in Nrf2 KO mice, and the exercise capacity of WT mice was significantly higher than that of Nrf2 KO mice. These findings suggest HP promotes exercise capacity of mice with the participation of the Nrf2 signal in skeletal muscle.

NEW & NOTEWORTHY Hypoxia preconditioning (HP) activated the nuclear factor erythroid 2-related factor 2 (Nrf2) signal, which was involved in HP-elicited adaptation responses to hypoxia, oxidative, and metabolic stresses in skeletal muscle. On the other hand, Nrf2 deficiency abolished the enhanced exercise capacity after the 48-h HP. Our results indicate that Nrf2 plays an essential role in the exercise capacity-enhancing effect of HP, possibly by modulating muscular antioxidative responses, the mRNA expression of muscular genes involved in glycogen and fatty acid metabolism, as well as mitochondrial biogenesis, and through the cross talk with AMPK and hypoxia-inducible factor-1α signaling.

Natural constituents from food sources: potential therapeutic agents against muscle wasting

Skeletal muscle wasting is highly correlated with not only reduced quality of life but also higher morbidity and mortality. Although an increasing number of patients are suffering from various kinds of muscle atrophy and weakness, there is still no effective therapy available, and skeletal muscle is considered as an under-medicated organ. Food provided not only essential macronutrients but also functional substances involved in the modulation of the physiological systems of our body. Natural constituents from commonly consumed dietary plants, either extracts or compounds, have attracted more and more attention to be developed as agents for preventing and treating muscle wasting due to their safety and effectiveness, as well as structural diversity. This review provides an overview of the mechanistic aspects of muscle wasting, and summarizes the extracts and compounds from food sources as potential therapeutic agents against muscle wasting.

The Efficacy of Administering Fruit-Derived Polyphenols to Improve Health Biomarkers, Exercise Performance and Related Physiological Responses

Polyphenols are secondary metabolites involved in a myriad of critical processes in plants. Over recent decades, special attention has been paid to the anti-oxidative role of fruit-derived polyphenols in the human diet, with evidence supporting the contribution of polyphenols in the prevention of numerous non-communicable disease outcomes. However, due to the low concentration in biological fluids in vivo, the antioxidant properties of polyphenols seem to be related to an enhanced endogenous antioxidant capacity induced via signaling through the nuclear respiratory factor 2 pathway. Polyphenols also seem to possess anti-inflammatory and antioxidant properties and have been shown to enhance vascular function via nitric oxide mediated mechanisms. Consequently, there is rationale to support fruit-derived polyphenol supplementation to enhance exercise performance, possibly via improved muscle perfusion. Fruit-derived polyphenol supplementation in exercise studies have included a variety of fruits, e.g., New Zealand blackcurrant, pomegranate, and cherry, in the form of extracts (multicomponent or purified), juices and infusions to varying degrees of benefit. For example, research has yet to link the health-related benefits of black elderberry (Sambucus nigra L.) ingestion to exercise performance in spite of the purported health benefits associated with black elderberry provision in vitro and in vivo models, which has been attributed to their high antioxidant capacity and polyphenol content. This review summarizes the existing evidence supporting a beneficial effect of fruit-derived polyphenols on various biological processes and outlines the potential for black elderberry ingestion to improve nitric oxide production, exercise performance, and the associated physiological responses before-, during- and post-exercise.

Oral supplementation with p-coumaric acid protects mice against diabetes-associated spontaneous destruction of periodontal tissue

OBJECTIVE

Dietary bioactive materials having anti-inflammatory and antioxidant potentials are able to inhibit diabetes-associated periodontal complications. Although numerous studies indicate that administration of p-coumaric acid (p-CA) ameliorates diabetes and diabetes-related complications, the roles of p-CA on periodontal tissue destruction in diabetic mice and the possible mechanisms therein are not completely understood. In this study, we evaluated whether supplementation with p-CA protects mice against diabetes-associated spontaneous periodontal destruction and also explored the associated mechanism therein using in vivo and in vitro experimental systems.

MATERIALS AND METHODS

C57BL/6 male mice were divided into sham, streptozotocin (STZ), and STZ+CA groups (n = 5/group). Sham group was intraperitoneally injected with sodium buffer, whereas other two groups were injected with the buffer containing 160 mg/kg of STZ. STZ-induced diabetic mice received oral gavage with p-CA (50 mg/kg) (STZ+CA group) or with buffer only (STZ group) daily for 6 weeks. The effect of p-CA on diabetes-associated spontaneous periodontal destruction was evaluated using μCT analysis, hematoxylin and eosin staining, tartrate-resistant acid phosphatase staining, and immunohistochemical staining methods. The efficacies of p-CA on cell proliferation, osteoblast differentiation, reactive oxygen species (ROS) accumulation, and antioxidant-related marker expression were examined using human periodontal ligament fibroblasts (hPLFs) cultured under high glucose condition.

RESULTS

Streptozotocin group exhibited periodontal tissue destruction along with increased inflammation, oxidative stress, and osteoclast formation, as well as with decreased osteogenesis. However, oral administration with p-CA protected mice against STZ-induced periodontal destruction by inhibiting inflammation and osteoclastic activation. STZ+CA group also showed higher expression of antioxidant and osteogenic markers in periodontal tissue than did STZ group. Treatment with high glucose concentration (30 mmol/L) impaired proliferation and osteoblast differentiation of hPLFs along with cellular ROS accumulation, whereas these impairments were almost completely disappeared by supplementation with p-CA.

CONCLUSION

These findings demonstrate that supplementation with p-CA inhibits diabetes-associated spontaneous destruction of periodontal tissue by enhancing anti-inflammatory, anti-osteoclastogenic, and antioxidant defense systems in STZ-treated mice.

Exercise-Induced Mitohormesis for the Maintenance of Skeletal Muscle and Healthspan Extension

Oxidative damage is one mechanism linking aging with chronic diseases including the progressive loss of skeletal muscle mass and function called sarcopenia. Thus, mitigating oxidative damage is a potential avenue to prevent or delay the onset of chronic disease and/or extend healthspan. Mitochondrial hormesis (mitohormesis) occurs when acute exposure to stress stimulates adaptive mitochondrial responses that improve mitochondrial function and resistance to stress. For example, an acute oxidative stress via mitochondrial superoxide production stimulates the activation of endogenous antioxidant gene transcription regulated by the redox sensitive transcription factor Nrf2, resulting in an adaptive hormetic response. In addition, acute stresses such as aerobic exercise stimulate the expansion of skeletal muscle mitochondria (i.e., mitochondrial biogenesis), constituting a mitohormetic response that protects from sarcopenia through a variety of mechanisms. This review summarized the effects of age-related declines in mitochondrial and redox homeostasis on skeletal muscle protein homeostasis and highlights the mitohormetic mechanisms by which aerobic exercise mitigates these age-related declines and maintains function. We discussed the potential efficacy of targeting the Nrf2 signaling pathway, which partially mediates adaptation to aerobic exercise, to restore mitochondrial and skeletal muscle function. Finally, we highlight knowledge gaps related to improving redox signaling and make recommendations for future research.

Antioxidant and Adaptative Response Mediated by Nrf2 during Physical Exercise

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a powerful nuclear transcription factor that coordinates an antioxidant cytoprotector system complex stimulated by the increase in inoxidative stress (OS). In the present manuscript, we conduct a review on the evidence that shows the effect different modalities of physical exercise exert on the antioxidant metabolic response directed by Nrf2. During physical exercise, the reactive oxygen species (ROS) are increased; therefore, if the endogenous and exogenous antioxidant defenses are unable to control the elevation of ROS, the resulting OS triggers the activation of the transcriptional factor Nrf2 to induce the antioxidant response. On a molecular basis related to physical exercise, hormesis maintenance (exercise preconditioning) and adaptative changes in training are supported by a growing body of evidence, which is important for detailing the health benefits that involve greater resistance to environmental aggressions, better tolerance to constant changes, and increasing the regenerative capacity of the cells in such a way that it may be used as a tool to support the prevention or treatment of diseases. This may have clinical implications for future investigations regarding physical exercise in terms of understanding adaptations in high-performance athletes but also as a therapeutic model in several diseases.

Looking beyond PGC-1α: emerging regulators of exercise-induced skeletal muscle mitochondrial biogenesis and their activation by dietary compounds

Despite its widespread acceptance as the "master regulator" of mitochondrial biogenesis (i.e., the expansion of the mitochondrial reticulum), peroxisome proliferator-activated receptor (PPAR) gamma coactivator-1 alpha (PGC-1α) appears to be dispensable for the training-induced augmentation of skeletal muscle mitochondrial content and respiratory function. In fact, a number of regulatory proteins have emerged as important players in skeletal muscle mitochondrial biogenesis and many of these proteins share key attributes with PGC-1α. In an effort to move past the simplistic notion of a "master regulator" of mitochondrial biogenesis, we highlight the regulatory mechanisms by which nuclear factor erythroid 2-related factor 2 (Nrf2), estrogen-related receptor gamma (ERRγ), PPARβ, and leucine-rich pentatricopeptide repeat-containing protein (LRP130) may contribute to the control of skeletal muscle mitochondrial biogenesis. We also present evidence supporting/refuting the ability of sulforaphane, quercetin, and epicatechin to promote skeletal muscle mitochondrial biogenesis and their potential to augment mitochondrial training adaptations. Targeted activation of specific pathways by these compounds may allow for greater mechanistic insight into the molecular pathways controlling mitochondrial biogenesis in human skeletal muscle. Dietary activation of mitochondrial biogenesis may also be useful in clinical populations with basal reductions in mitochondrial protein content, enzyme activities, and/or respiratory function as well as individuals who exhibit a blunted skeletal muscle responsiveness to contractile activity. Novelty The existence of redundant pathways leading to mitochondrial biogenesis refutes the simplistic notion of a "master regulator" of mitochondrial biogenesis. Dietary activation of specific pathways may provide greater mechanistic insight into the exercise-induced mitochondrial biogenesis in human skeletal muscle.

The Anti-Inflammatory and Anti-Oxidant Mechanisms of the Keap1/Nrf2/ARE Signaling Pathway in Chronic Diseases

Oxidative stress is defined as an imbalance between production of free radicals and reactive metabolites or [reactive oxygen species (ROS)] and their elimination by through protective mechanisms, including (antioxidants). This Such imbalance leads to damage of cells and important biomolecules and cells, with hence posing a potential adverse impact on the whole organism. At the center of the day-to-day biological response to oxidative stress is the Kelch-like ECH-associated protein 1 (Keap1) - nuclear factor erythroid 2-related factor 2 (Nrf2)- antioxidant response elements (ARE) pathway, which regulates the transcription of many several antioxidant genes that preserve cellular homeostasis and detoxification genes that process and eliminate carcinogens and toxins before they can cause damage. The redox-sensitive signaling system Keap1/Nrf2/ARE plays a key role in the maintenance of cellular homeostasis under stress, inflammatory, carcinogenic, and pro-apoptotic conditions, which allows us to consider it as a pharmacological target. Herein, we review and discuss the recent advancements in the regulation of the Keap1/Nrf2/ARE system, and its role under physiological and pathophysiological conditions, e.g. such as in exercise, diabetes, cardiovascular diseases, cancer, neurodegenerative disorders, stroke, liver and kidney system, etc. and such.

Piceatannol markedly upregulates heme oxygenase-1 expression and alleviates oxidative stress in skeletal muscle cells

Piceatannol (PIC), a phytochemical, is abundant in passion fruit (Passiflora edulis) seeds. In this study, we investigated the effects of PIC on the expression levels of antioxidant enzymes in C2C12 skeletal muscle cells and compared its effects with those of PIC analogues and polyphenols. We also evaluated its effects on hydrogen peroxide–induced accumulation of reactive oxygen species in C2C12 myotubes. Treatment with PIC led to dose-dependent upregulation of heme oxygenase-1 (Ho-1) and superoxide dismutase 1 (Sod1) mRNA expression in C2C12 myotubes. PIC was the most potent inducer of Ho-1 among the PIC analogues and major polyphenols tested. In addition, treatment with PIC suppressed the hydrogen peroxide–induced increase in intracellular reactive oxygen species levels. Our results suggest that PIC protects skeletal muscles from oxidative stress by activating antioxidant enzymes such as HO-1 and SOD1 and can therefore help prevent oxidative stress–induced muscle dysfunction such as muscle fatigue and sarcopenia.

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PIC induced antioxidant enzymes in C2C12 skeletal muscle cell line.

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PIC was the most potent inducer of Ho-1 among other polyphenols tested.

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Induction potency of PIC for Sod1 was similar level with those of other polyphenols.

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PIC suppressed the hydrogen peroxide-induced increase in intracellular ROS levels.

Myocardial NADPH oxidase-4 regulates the physiological response to acute exercise

Regular exercise has widespread health benefits. Fundamental to these beneficial effects is the ability of the heart to intermittently and substantially increase its performance without incurring damage, but the underlying homeostatic mechanisms are unclear. We identify the ROS-generating NADPH oxidase-4 (Nox4) as an essential regulator of exercise performance in mice. Myocardial Nox4 levels increase during acute exercise and trigger activation of the transcription factor Nrf2, with the induction of multiple endogenous antioxidants. Cardiomyocyte-specific Nox4-deficient (csNox4KO) mice display a loss of exercise-induced Nrf2 activation, cardiac oxidative stress and reduced exercise performance. Cardiomyocyte-specific Nrf2-deficient (csNrf2KO) mice exhibit similar compromised exercise capacity, with mitochondrial and cardiac dysfunction. Supplementation with an Nrf2 activator or a mitochondria-targeted antioxidant effectively restores cardiac performance and exercise capacity in csNox4KO and csNrf2KO mice respectively. The Nox4/Nrf2 axis therefore drives a hormetic response that is required for optimal cardiac mitochondrial and contractile function during physiological exercise.

Cellular and molecular mechanisms of sarcopenia: the S100B perspective

Primary sarcopenia is a condition of reduced skeletal muscle mass and strength, reduced agility, and increased fatigability and risk of bone fractures characteristic of aged, otherwise healthy people. The pathogenesis of primary sarcopenia is not completely understood. Herein, we review the essentials of the cellular and molecular mechanisms of skeletal mass maintenance; the alterations of myofiber metabolism and deranged properties of muscle satellite cells (the adult stem cells of skeletal muscles) that underpin the pathophysiology of primary sarcopenia; the role of the Ca²⁺ -sensor protein, S100B, as an intracellular factor and an extracellular signal regulating cell functions; and the functional role of S100B in muscle tissue. Lastly, building on recent results pointing to S100B as to a molecular determinant of myoblast-brown adipocyte transition, we propose S100B as a transducer of the deleterious effects of accumulation of reactive oxygen species in myoblasts and, potentially, myofibers concurring to the pathophysiology of sarcopenia.