Systemic and mitochondrial adaptive responses to moderate exercise in rodents

The mitochondrial quality control system: a new target for exercise therapeutic intervention in the treatment of brain insulin resistance-induced neurodegeneration in obesity

Obesity is a major global health concern because of its strong association with metabolic and neurodegenerative diseases such as diabetes, dementia, and Alzheimer's disease. Unfortunately, brain insulin resistance in obesity is likely to lead to neuroplasticity deficits. Since the evidence shows that insulin resistance in brain regions abundant in insulin receptors significantly alters mitochondrial efficiency and function, strategies targeting the mitochondrial quality control system may be of therapeutic and practical value in obesity-induced cognitive decline. Exercise is considered as a powerful stimulant of mitochondria that improves insulin sensitivity and enhances neuroplasticity. It has great potential as a non-pharmacological intervention against the onset and progression of obesity associated neurodegeneration. Here, we integrate the current knowledge of the mechanisms of neurodegenration in obesity and focus on brain insulin resistance to explain the relationship between the impairment of neuronal plasticity and mitochondrial dysfunction. This knowledge was synthesised to explore the exercise paradigm as a feasible intervention for obese neurodegenration in terms of improving brain insulin signals and regulating the mitochondrial quality control system.

Effects of Resistance Exercise and Essential Amino Acid Intake on Muscle Quality, Myokine, and Inflammation Factors in Young Adult Males

BACKGROUND

Recently, many studies have been devoted to discovering nutrients for exercise-like effects. Resistance exercise and the intake of essential amino acids (EAAs) are known to be factors that can affect muscle mass and strength improvement. The purpose of this study was to investigate changes in muscle quality, myokines, and inflammation in response to resistance exercise and EAA supplementation.

METHODS

Thirty-four males volunteered to participate in this study. They were assigned to four groups: (1) placebo (CO), (2) resistance exercise (RE), (3) EAA supplementation, and (4) RE + EAA supplementation. Body composition, muscle quality, myokines, and inflammation were measured at baseline and four weeks after treatment.

RESULTS

Lean body fat had decreased in both RE and RE + EAA groups. Lean body mass had increased in only the RE + EAA group. In all groups except for CO, irisin, myostatin A, and TNF-α levels had decreased. The grip strength of the right hand and trunk flexion peak torque increased in the RE group. The grip strength of the left hand, trunk flexion peak torque, and knee flexion peak torque of the left leg were increased in RE + EAA.

CONCLUSIONS

RE, EAA, and RE + EAA could effectively improve the muscle quality, myokine, and inflammation factors of young adult males. This finding highlights the importance of resistance exercise and amino acid intake.

Exercise intensity and sex alter neurometabolic, transcriptional, and functional recovery following traumatic brain injury

Physical exercise represents a potentially inexpensive, accessible, and optimizable rehabilitation approach to traumatic brain injury (TBI) recovery. However, little is known about the impact of post-injury exercise on the neurometabolic, transcriptional, and cognitive outcomes following a TBI. In the current study, we examined TBI outcomes in adolescent male and female mice following a controlled cortical impact (CCI) injury. Mice underwent a 10-day regimen of sedentary, low-, moderate-, or high-intensity treadmill exercise and were assessed for cognitive function, histopathology, mitochondrial function, and oxidative stress. Among male mice, low-moderate exercise improved cognitive recovery, and reduced cortical lesion volume and oxidative stress, whereas high-intensity exercise impaired both cognitive recovery and mitochondrial function. On the other hand, among female mice, exercise had an intermediate effect on cognitive recovery but significantly improved brain mitochondrial function. Moreover, single nuclei RNA sequencing of perilesional brain tissue revealed neuronal plasticity-related differential gene expression that was largely limited to the low-intensity exercise injured males. Taken together, these data build on previous reports of the neuroprotective capacity of exercise in a TBI model, and reveal that this rehabilitation strategy impacts neurometabolic, functional, and transcriptional outcome measures in an intensity- and sex-dependent manner.

High-Intensity Interval Training Improves Glycemic Control, Cellular Apoptosis, and Oxidative Stress of Type 2 Diabetic Patients

Background and Objectives: Physical exercise is an important therapeutic modality for treating and managing diabetes. High-intensity interval training (HIIT) is considered one of the best non-drug strategies for preventing and treating type 2 diabetes mellitus (T2DM) by improving mitochondrial biogenesis and function. This study aimed to determine the effects of 12 weeks of HIIT training on the expression of tumor suppressor protein-p53, mitochondrial cytochrome c oxidase (COX), and oxidative stress in patients with T2DM. Methods: A total of thirty male sedentary patients aged (45-60 years) were diagnosed with established T2DM for more than five years. Twenty healthy volunteers, age- and sex-matched, were included in this study. Both patients and control subjects participated in the HIIT program for 12 weeks. Glycemic control variables including p53 (U/mL), COX (ng/mL), total antioxidant capacity (TAC, nmole/µL), 8-hydroxy-2'-deoxyguanosine (8-OHdG, ng/mL), as well as genomic and mitochondrial DNA content were measured in both the serum and muscle tissues of control and patient groups following exercise training. Results: There were significant improvements in fasting glucose levels. HbA1c (%), HOMA-IR (mUmmol/L2), fasting insulin (µU/mL), and C-peptide (ng/mL) were reported in T2DM and healthy controls. A significant decrease was also observed in p53 protein levels. COX, 8-OhdG, and an increase in the level of TAC were reported in T2DM following 12 weeks of HIIT exercise. Before and after exercise, p53; COX, mt-DNA content, TAC, and 8-OhdG showed an association with diabetic control parameters such as fasting glucose (FG), glycated hemoglobin (HbA1C, %), C-peptide, fasting insulin (FI), and homeostatic model assessment for insulin resistance (HOMA-IR) in patients with T2DM. These findings support the positive impact of HIIT exercise in improving regulation of mitochondrial biogenesis and subsequent control of diabetes through anti-apoptotic and anti-oxidative pathways. Conclusions: A 12-week HIIT program significantly improves diabetes by reducing insulin resistance; regulating mitochondrial biogenesis; and decreasing oxidative stress capacity among patients and healthy controls. Also; p53 protein expression; COX; 8-OhdG; and TAC and mt-DNA content were shown to be associated with T2DM before and after exercise training.

Exercise adaptations and TGF-β1 levels in recreational cyclists

Background

Cycling is a physical exercise that is widely performed to improve physical fitness. Regular physical exercise will lead to adaptations to exercise. This adaptation is useful in suppressing the production of reactive oxygen stress (ROS) generated in response to cellular metabolism that uses oxygen. Transforming growth factor beta-1 (TGF-β1) plays a role in increasing the production of ROS, thus, when the concentration is low, it would lead to an improvement in physical fitness. This study aims to compare levels of TGF-β1 between recreational cyclists and sedentary groups. In addition, this research also compares several other parameters, which are fasting blood sugar levels and lipid profiles (triglycerides, total cholesterol, HDL cholesterol, and LDL cholesterol) between cyclists and sedentaries.

Methods

This was an observational analytical study with a cross-sectional design. The research subjects consisted of 2 groups, each consisting of 21 participants, namely the recreational cyclist and the sedentary group. Anthropometric examinations were carried out, including body weight, height, body mass index, waist circumference, and body fat percentage. Fasting blood glucose concentration and lipid profile (Triglyceride – TG, Total Cholesterol – Total C, HDL Cholesterol – HDL-C, and LDL Cholesterol – LDL-C) were determined by the enzymatic colorimetric methods, and TGF-β1 levels were determined using the fluorescence of specific antibodies for TGF-β1 (pg/ml) using ELISA method. Statistical analysis was performed using IBM SPSS v. 25.

Results

The anthropometric variables, other than body height, did not differ significantly between the two groups, so did the fasting blood glucose concentration. Nevertheless, the lipid profile (TG, Total C, HDL-C and LDL-C) were found to be significantly better in the cyclist group (p < 0.05).

The mean level of TGF-β1 in recreational cyclists was 8, 908.48 pg/ml, lower than the control group, 10, 229.28 pg/ml. The results of the unpaired t-test showed significant mean differences between the two groups, (p = 0.001; p < 0.05).

Conclusion

The levels of TGF-β1 in the recreational cyclist group were lower than the sedentary group. Regular physical exercise will trigger exercise adaptations that can suppress latent TGF-β1 activation.

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This study aims to compare levels of TGF-β1 between recreational cyclists and sedentary groups

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The research subjects consisted of 2 groups, each consisting of 21 participants, namely the recreational cyclist and the sedentary group.

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Anthropometric examinations were carried out, including body weight, height, body mass index, waist circumference, and body fat percentage

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The levels of TGF-β1 in the recreational cyclist group were lower than the sedentary group

The central role of mitochondrial fitness on antiviral defenses: An advocacy for physical activity during the COVID-19 pandemic

Mitochondria are central regulators of cellular metabolism, most known for their role in energy production. They can be "enhanced" by physical activity (including exercise), which increases their integrity, efficiency and dynamic adaptation to stressors, in short "mitochondrial fitness". Mitochondrial fitness is closely associated with cardiorespiratory fitness and physical activity. Given the importance of mitochondria in immune functions, it is thus not surprising that cardiorespiratory fitness is also an integral determinant of the antiviral host defense and vulnerability to infection. Here, we first briefly review the role of physical activity in viral infections. We then summarize mitochondrial functions that are relevant for the antiviral immune response with a particular focus on the current Coronavirus Disease (COVID-19) pandemic and on innate immune function. Finally, the modulation of mitochondrial and cardiorespiratory fitness by physical activity, aging and the chronic diseases that represent the most common comorbidities of COVID-19 is discussed. We conclude that a high mitochondrial - and related cardiorespiratory - fitness should be considered as protective factors for viral infections, including COVID-19. This assumption is corroborated by reduced mitochondrial fitness in many established risk factors of COVID-19, like age, various chronic diseases or obesity. We argue for regular analysis of the cardiorespiratory fitness of COVID-19 patients and the promotion of physical activity - with all its associated health benefits - as preventive measures against viral infection.

The Muscle-Brain Axis and Neurodegenerative Diseases: The Key Role of Mitochondria in Exercise-Induced Neuroprotection

Regular exercise is associated with pronounced health benefits. The molecular processes involved in physiological adaptations to exercise are best understood in skeletal muscle. Enhanced mitochondrial functions in muscle are central to exercise-induced adaptations. However, regular exercise also benefits the brain and is a major protective factor against neurodegenerative diseases, such as the most common age-related form of dementia, Alzheimer's disease, or the most common neurodegenerative motor disorder, Parkinson's disease. While there is evidence that exercise induces signalling from skeletal muscle to the brain, the mechanistic understanding of the crosstalk along the muscle-brain axis is incompletely understood. Mitochondria in both organs, however, seem to be central players. Here, we provide an overview on the central role of mitochondria in exercise-induced communication routes from muscle to the brain. These routes include circulating factors, such as myokines, the release of which often depends on mitochondria, and possibly direct mitochondrial transfer. On this basis, we examine the reported effects of different modes of exercise on mitochondrial features and highlight their expected benefits with regard to neurodegeneration prevention or mitigation. In addition, knowledge gaps in our current understanding related to the muscle-brain axis in neurodegenerative diseases are outlined.

Aerobic Exercise in the Management of Metabolic Dysfunction Associated Fatty Liver Disease

Sedentarism is the pandemic of modern times. It is associated with several medical conditions including obesity, type 2 diabetes mellitus, cardiovascular diseases and also liver disease, particularly metabolic dysfunction associated fatty liver disease (MAFLD). In an era when MAFLD is the most prevalent chronic liver disease worldwide, whilst no pharmacological therapy has been approved for it, exercise has proved to be effective in improving liver steatosis. Interestingly, exercise decreases liver fat even in the absence of weight loss. The challenge for the clinician is to motivate the obese patient with MAFLD, and associated co-morbidities, who has crystallized a sedentary behavior, at times when every need is at the distance of a click on the Internet, and the entire world can be visited behind a screen. In this review, the aggregate evidence on the mechanisms and effects of exercise in the management of MAFLD is summarized, with simple recommendations for everyday clinical practice.

Impact of Exercise on Immunometabolism in Multiple Sclerosis

Multiple Sclerosis (MS) is a chronic, autoimmune condition characterized by demyelinating lesions and axonal degradation. Even though the cause of MS is heterogeneous, it is known that peripheral immune invasion in the central nervous system (CNS) drives pathology at least in the most common form of MS, relapse-remitting MS (RRMS). The more progressive forms’ mechanisms of action remain more elusive yet an innate immune dysfunction combined with neurodegeneration are likely drivers. Recently, increasing studies have focused on the influence of metabolism in regulating immune cell function. In this regard, exercise has long been known to regulate metabolism, and has emerged as a promising therapy for management of autoimmune disorders. Hence, in this review, we inspect the role of key immunometabolic pathways specifically dysregulated in MS and highlight potential therapeutic benefits of exercise in modulating those pathways to harness an anti-inflammatory state. Finally, we touch upon current challenges and future directions for the field of exercise and immunometabolism in MS.

The patterns of exercise-induced β-endorphin expression in the central nervous system of rats

Exercise at different intensities is able to induce different physical and psychological statuses of the subjects. The β-endorphin (β-EP) in central nervous system is thought to play an important role in physical exercise. However, its expression patterns and physiological effects in the central nuclei under different exercise states are not well understood. Five-week old male Sprague-Dawley rats were randomly divided into two groups of 21 each: Control and Exercise. Control rats were sedentary while Exercise rats were arranged to run on a treadmill (5-week adapting or moderate exercise and 2-week high-intensity exercise). Seven rats were taken from each group at day33, day42 and day49 for examination of blood biochemical parameters (lactate, Lac; blood urea nitrogen, BUN; glucose) and for detection of nuclei β-EP level with immunohistochemistry. The results showed that Lac and BUN levels were significant increased after the high intensity exercise. The five-week exercise caused a significantly increased β-EP in caudate putamen (CPu), amygdala, paraventricular thalamic nucleus (PVT), ventromedial hypothalamus nucleus (VMH) and gigantocellular reticular nucleus (Gi). The high intensity exercise induced an elevated β-EP in CPu and nucleus of the solitary tract (Sol), but a decreased β-EP in globus pallidus (GP). Compared with Control, exercise rats showed an elevated β-EP in CPu, PVT, VMH, accumbens nucleus, Gi and Sol, and a decreased β-EP in GP at day49. The β-EP levels in acurate nucleus, periadueductal gray and parabrachial nucleus were not changed at day33, 42 and 49. In conclusion, β-EP levels in different nuclei changed under the moderate and high intensity exercises, which may contribute to modifying exercise-produced psychological and physiological effects.

The role of mitochondrial bioenergetics and oxidative stress in depressive behavior in recurrent concussion model in mice

Traumatic brain injury (TBI) is a public health problem in which even though 80 to 90% of cases are considered mild, usually starts a sequence of neurological disorders that can last a considerable time. Most of the research of this injury has been focused on oxidative stress and functional deficits; however, mechanisms that underlie the development of neuropsychiatric disorders remain little researched. Due to this, the present authors decided to investigate whether recurrent concussion protocols alter depressive-like phenotype behavior, and whether mitochondria play an indispensable role in this behavior or not. The experimental data revealed, for the first time, that the present protocol of recurrent concussions (4, 7, and 10 injuries) in mice did not alter immobility time during tail suspension tests (TSTs), but decreased hippocampal mitochondrial respiration and increased expression of proteins such as nuclear factor erythroid 2-related factor 2 (Nrf2) and superoxide (SOD2). This experimental data suggests that bioenergetic changes elicited by recurrent concussion did not induce depressive-like behavior, but activated the transcription factor of responsive antioxidant elements (ARE) that delay or prevent secondary cascades in this neurological disease.

Improved Calcium Homeostasis and Force by Selenium Treatment and Training in Aged Mouse Skeletal Muscle

During aging reduction in muscle mass (sarcopenia) and decrease in physical activity lead to partial loss of muscle force and increased fatigability. Deficiency in the essential trace element selenium might augment these symptoms as it can cause muscle pain, fatigue, and proximal weakness. Average voluntary daily running, maximal twitch and tetanic force, and calcium release from the sarcoplasmic reticulum (SR) decreased while reactive oxygen species (ROS) production associated with tetanic contractions increased in aged – 22-month-old – as compared to young – 4-month-old – mice. These changes were accompanied by a decline in the ryanodine receptor type 1 (RyR1) and Selenoprotein N content and the increased amount of a degraded RyR1. Both lifelong training and selenium supplementation, but not the presence of an increased muscle mass at young age, were able to compensate for the reduction in muscle force and SR calcium release with age. Selenium supplementation was also able to significantly enhance the Selenoprotein N levels in aged mice. Our results describe, for the first time, the beneficial effects of selenium supplementation on calcium release from the SR and muscle force in old age while point out that increased muscle mass does not improve physical performance with aging.

Moderate Exercise in Spontaneously Hypertensive Rats Is Unable to Activate the Expression of Genes Linked to Mitochondrial Dynamics and Biogenesis in Cardiomyocytes

Hypertension (HTN) is a public health concern and a major preventable cause of cardiovascular disease (CVD). When uncontrolled, HTN may lead to adverse cardiac remodeling, left ventricular hypertrophy, and ultimately, heart failure. Regular aerobic exercise training exhibits blood pressure protective effects, improves myocardial function, and may reverse pathologic cardiac hypertrophy. These beneficial effects depend at least partially on improved mitochondrial function, decreased oxidative stress, endothelial dysfunction, and apoptotic cell death, which supports the general recommendation of moderate exercise in CVD patients. However, most of these mechanisms have been described on healthy individuals; the effect of moderate exercise on HTN subjects at a cellular level remain largely unknown. We hypothesized that hypertension in adult spontaneously hypertensive rats (SHRs) reduces the mitochondrial response to moderate exercise in the myocardium. Methods: Eight-month-old SHRs and their normotensive control-Wistar-Kyoto rats (WKYR)-were randomly assigned to moderate exercise on a treadmill five times per week with a running speed set at 10 m/min and 15° inclination. The duration of each session was 45 min with a relative intensity of 70-85% of the maximum O₂ consumption for a total of 8 weeks. A control group of untrained animals was maintained in their cages with short sessions of 10 min at 10 m/min two times per week to maintain them accustomed to the treadmill. After completing the exercise protocol, we assessed maximum exercise capacity and echocardiographic parameters. Animals were euthanized, and heart and muscle tissue were harvested for protein determinations and gene expression analysis. Measurements were compared using a nonparametric ANOVA (Kruskal-Wallis), with post-hoc Dunn's test. Results: At baseline, SHR presented myocardial remodeling evidenced by left ventricular hypertrophy (interventricular septum 2.08 ± 0.07 vs. 1.62 ± 0.08 mm, p < 0.001), enlarged left atria (0.62 ± 0.1 mm vs. 0.52 ± 0.1, p = 0.04), and impaired diastolic function (E/A ratio 2.43 ± 0.1 vs. 1.56 ± 0.2) when compared to WKYR. Moderate exercise did not induce changes in ventricular remodeling but improved diastolic filling pattern (E/A ratio 2.43 ± 0.1 in untrained SHR vs. 1.89 ± 0.16 trained SHR, p < 0.01). Histological analysis revealed increased myocyte transversal section area, increased Myh7 (myosin heavy chain 7) expression, and collagen fiber accumulation in SHR-control hearts. While the exercise protocol did not modify cardiac size, there was a significant reduction of cardiomyocyte size in the SHR-exercise group. Conversely, titin expression increased only WYK-exercise animals but remained unchanged in the SHR-exercise group. Mitochondrial response to exercise also diverged between SHR and WYKR: while moderate exercise showed an apparent increase in mRNA levels of Ppargc1α, Opa1, Mfn2, Mff, and Drp1 in WYKR, mitochondrial dynamics proteins remained unchanged in response to exercise in SHR. This finding was further confirmed by decreased levels of MFN2 and OPA1 in SHR at baseline and increased OPA1 processing in response to exercise in heart. In summary, aerobic exercise improves diastolic parameters in SHR but fails to activate the cardiomyocyte mitochondrial adaptive response observed in healthy individuals. This finding may explain the discrepancies on the effect of exercise in clinical settings and evidence of the need to further refine our understanding of the molecular response to physical activity in HTN subjects.

Exercise-Induced Regulation of Redox Status in Cardiovascular Diseases: The Role of Exercise Training and Detraining

Although low levels of reactive oxygen species (ROS) are beneficial for the organism ensuring normal cell and vascular function, the overproduction of ROS and increased oxidative stress levels play a significant role in the onset and progression of cardiovascular diseases (CVDs). This paper aims at providing a thorough review of the available literature investigating the effects of acute and chronic exercise training and detraining on redox regulation, in the context of CVDs. An acute bout of either cardiovascular or resistance exercise training induces a transient oxidative stress and inflammatory response accompanied by reduced antioxidant capacity and enhanced oxidative damage. There is evidence showing that these responses to exercise are proportional to exercise intensity and inversely related to an individual’s physical conditioning status. However, when chronically performed, both types of exercise amplify the antioxidant defense mechanism, reduce oxidative stress and preserve redox status. On the other hand, detraining results in maladaptations within a time-frame that depends on the exercise training intensity and mode, as high-intensity training is superior to low-intensity and resistance training is superior to cardiovascular training in preserving exercise-induced adaptations during detraining periods. Collectively, these findings suggest that exercise training, either cardiovascular or resistance or even a combination of them, is a promising, safe and efficient tool in the prevention and treatment of CVDs.

Peripheral blood metabolome predicts mood change-related activity in mouse model of bipolar disorder

Bipolar disorder is a major mental illness characterized by severe swings in mood and activity levels which occur with variable amplitude and frequency. Attempts have been made to identify mood states and biological features associated with mood changes to compensate for current clinical diagnosis, which is mainly based on patients' subjective reports. Here, we used infradian (a cycle > 24 h) cyclic locomotor activity in a mouse model useful for the study of bipolar disorder as a proxy for mood changes. We show that metabolome patterns in peripheral blood could retrospectively predict the locomotor activity levels. We longitudinally monitored locomotor activity in the home cage, and subsequently collected peripheral blood and performed metabolomic analyses. We then constructed cross-validated linear regression models based on blood metabolome patterns to predict locomotor activity levels of individual mice. Our analysis revealed a significant correlation between actual and predicted activity levels, indicative of successful predictions. Pathway analysis of metabolites used for successful predictions showed enrichment in mitochondria metabolism-related terms, such as "Warburg effect" and "citric acid cycle." In addition, we found that peripheral blood metabolome patterns predicted expression levels of genes implicated in bipolar disorder in the hippocampus, a brain region responsible for mood regulation, suggesting that the brain-periphery axis is related to mood-change-associated behaviors. Our results may serve as a basis for predicting individual mood states through blood metabolomics in bipolar disorder and other mood disorders and may provide potential insight into systemic metabolic activity in relation to mood changes.

Low-level cyclic tibial compression attenuates early osteoarthritis progression after joint injury in mice

OBJECTIVE

Mechanical loading and joint health have a unique relationship in osteoarthritis (OA) onset and progression. Although high load levels adversely affect cartilage health, exercise that involves low to moderate load levels can alleviate OA symptoms. We sought to isolate the beneficial effects of mechanical loading using controlled in vivo cyclic tibial compression. We hypothesized that low-level cyclic compression would attenuate post-traumatic OA symptoms induced by destabilization of the medial meniscus (DMM).

METHODS

10-week-old C57Bl/6J male mice underwent DMM surgery (n = 51). After a 5-day post-operative recovery period, we applied daily cyclic tibial compression to the operated limbs at low (1.0N or 2.0N) or moderate (4.5N) magnitudes for 2 or 6 weeks. At the completion of loading, we compared cartilage and peri-articular bone features of mice that underwent DMM and loading to mice that only underwent DMM.

RESULTS

Compared to DMM alone, low-level cyclic compression for 6 weeks attenuated DMM-induced cartilage degradation (OARSI score, P = 0.008, 95% confidence interval (CI): 0.093 to 0.949). Low-level loading attenuated DMM-induced osteophyte formation after 2 weeks (osteophyte size, P = 0.033, 95% CI: 3.27-114.45 μm), and moderate loading attenuated subchondral bone sclerosis after 6 weeks (tissue mineral density (TMD), P = 0.011, 95% CI: 6.32-70.60 mg HA/ccm) compared to limbs that only underwent DMM. Finally, loading had subtle beneficial effects on cartilage cellularity and aggrecanase activity after DMM.

CONCLUSION

Low-level cyclic compression is beneficial to joint health after an injury. Therefore, the progression of early OA may be attenuated by applying well controlled, low-level loading shortly following joint trauma.

Exercise effects on physiological function during aging

The decrease in cognitive/motor functions and physical abilities severely affects the aging population in carrying out daily activities. These disabilities become a burden on individuals, families and society in general. It is known that aging conditions are ameliorated with regular exercise, which attenuates the age-associated decline in maximal oxygen uptake (VO2max), production of reactive oxygen species (ROS), decreases in oxidative damage to molecules, and functional impairment in various organs. While benefits of physical exercise are well-documented, the molecular mechanisms responsible for functional improvement and increases in health span are not well understood. Recent findings imply that exercise training attenuates the age-related deterioration in the cellular housekeeping system, which includes the proteasome, Lon protease, autophagy, mitophagy, and DNA repair systems, which beneficially impacts multiple organ functions. Accumulating evidence suggests that exercise lessens the deleterious effects of aging. However, it seems unlikely that systemic effects are mediated through a specific biomarker. Rather, complex multifactorial mechanisms are involved to maintain homeostatic functions that tend to decline with age.

Emerging Anti-Aging Strategies - Scientific Basis and Efficacy

The prevalence of age-related diseases is in an upward trend due to increased life expectancy in humans. Age-related conditions are among the leading causes of morbidity and death worldwide currently. Therefore, there is an urgent need to find apt interventions that slow down aging and reduce or postpone the incidence of debilitating age-related diseases. This review discusses the efficacy of emerging anti-aging approaches for maintaining better health in old age. There are many anti-aging strategies in development, which include procedures such as augmentation of autophagy, elimination of senescent cells, transfusion of plasma from young blood, intermittent fasting, enhancement of adult neurogenesis, physical exercise, antioxidant intake, and stem cell therapy. Multiple pre-clinical studies suggest that administration of autophagy enhancers, senolytic drugs, plasma from young blood, drugs that enhance neurogenesis and BDNF are promising approaches to sustain normal health during aging and also to postpone age-related neurodegenerative diseases such as Alzheimer's disease. Stem cell therapy has also shown promise for improving regeneration and function of the aged or Alzheimer's disease brain. Several of these approaches are awaiting critical appraisal in clinical trials to determine their long-term efficacy and possible adverse effects. On the other hand, procedures such as intermittent fasting, physical exercise, intake of antioxidants such as resveratrol and curcumin have shown considerable promise for improving function in aging, some of which are ready for large-scale clinical trials, as they are non-invasive, and seem to have minimal side effects. In summary, several approaches are at the forefront of becoming mainstream therapies for combating aging and postponing age-related diseases in the coming years.

[Antioxidant and anti-inflammatory modulation of exercise during aging]

Aging is characterised by a gradual loss of the functional reserve. This, along with the fostering of sedentary habits and the increase in risk factors, causes a deterioration of antioxidant defences and an increase of the circulatory levels of inflammatory and oxidative markers, boosting a low-rate chronic inflammation, defined as inflamm-aging. This phenomenon is present in the aetiopathology of chronic diseases, as well as in cognitive deterioration cases associated with aging. The objective of this review is to describe the modulation of antioxidant and anti-inflammatory effects of physical exercise of moderate intensity and volume in the elderly. Evidence of its effectiveness as a non-pharmacological resource is presented, which decreases some deleterious effects of aging. This is mainly due to its neuroprotective action, the increase in circulating anti-inflammatory markers, and the improvement of antioxidant defence derived from its practice.

The Physiology of Exercise in Free-Living Vertebrates: What Can We Learn from Current Model Systems?

SYNOPSIS

Many behaviors crucial for survival and reproductive success in free-living animals, including migration, foraging, and escaping from predators, involve elevated levels of physical activity. However, although there has been considerable interest in the physiological and biomechanical mechanisms that underpin individual variation in exercise performance, to date, much work on the physiology of exercise has been conducted in laboratory settings that are often quite removed from the animal's ecology. Here we review current, laboratory-based model systems for exercise (wind or swim tunnels for migration studies in birds and fishes, manipulation of exercise associated with non-migratory activity in birds, locomotion in lizards, and wheel running in rodents) to identify common physiological markers of individual variation in exercise capacity and/or costs of increased activity. Secondly, we consider how physiological responses to exercise might be influenced by (1) the nature of the activity (i.e., voluntary or involuntary, intensity, and duration), and (2) resource acquisition and food availability, in the context of routine activities in free-living animals. Finally, we consider evidence that the physiological effects of experimentally-elevated activity directly affect components of fitness such as reproduction and survival. We suggest that developing more ecologically realistic laboratory systems, incorporating resource-acquisition, functional studies across multiple physiological systems, and a life-history framework, with reproduction and survival end-points, will help reveal the mechanisms underlying the consequences of exercise, and will complement studies in free-living animals taking advantage of new developments in wildlife-tracking.

Exosomes as Mediators of the Systemic Adaptations to Endurance Exercise

Habitual endurance exercise training is associated with multisystemic metabolic adaptations that lower the risk of inactivity-associated disorders such as obesity and type 2 diabetes mellitus (T2DM). Identification of complex systemic signaling networks responsible for these benefits are of great interest because of their therapeutic potential in metabolic diseases; however, specific signals that modulate the multisystemic benefits of exercise in multiple tissues and organs are only recently being discovered. Accumulated evidence suggests that muscle and other tissues have an endocrine function and release peptides and nucleic acids into the circulation in response to acute endurance exercise to mediate the multisystemic adaptations. Factors released from skeletal muscle have been termed myokines and we propose that the total of all factors released in response to endurance exercise (including peptides, nucleic acids, and metabolites) be termed, "exerkines." We propose that many of the exerkines are released within extracellular vesicles called exosomes, which regulate peripheral organ cross talk. Exosomes (30-140 nm) and larger microvesicles [MVs] (100-1000 nm) are subcategories of extracellular vesicles that are released into the circulation. Exosomes contain peptides and several nucleic acids (microRNA [miRNA], messenger RNA [mRNA], mitochondrial DNA [mtDNA]) and are involved in intercellular/tissue exchange of their contents. An acute bout of endurance exercise increases circulating exosomes that are hypothesized to mediate organ cross talk to promote systemic adaptation to endurance exercise. Further support for the role of exosomes (and possibly MVs) in mediating the systemic benefits of exercise comes from the fact that the majority of the previously reported myokines/exerkines are found in extracellular vesicles databases (Vesiclepedia and ExoCarta). We propose that exosomes isolated from athletes following exercise or exosomes bioengineered to incorporate one or many of known exerkines will be therapeutically useful in the treatment of obesity, T2DM, and other aging-associated metabolic disorders.

Behavioral effects of the combined use of alcohol and energy drinks on alcohol hangover in an experimental mice model

In last few years it has been a significant increase in the consumption of alcohol combined with energy drink. The aim of this work was to study the effect of this mixture in motor and affective behaviors during an alcohol hangover episode. Male Swiss mice received one of the following treatments: saline + sucrose; saline + energy drink; ethanol + sucrose; ethanol + energy drink. Ethanol dose was 3.8 g/kg BW (i.p.) and energy drink dose was 18 ml/kg BW (gavage) at ZT1 (8 am) (ZT: Zeitgeber time; ZT0: 7 am; lights on). The behavioral tests used were tight rope test to determine motor coordination; hanging wire test to study muscular strength; elevated plus maze and open field tests to evaluate anxiety like-behavior and locomotor activity. Tests were carried out at basal point that matched with lights onset and every 6 h up to 18 h after treatments. Hangover onset was established at ZT7 when blood alcohol concentration (BAC) was almost zero. Our results showed that the mixture of alcohol and energy drink altered significantly motor skills. Specifically, a significant decrease was observed in the performance of the animals in the tightrope and hanging wire tests in groups treated with the mixture of alcohol and energy drink. A significant impairment in the anxiety-like behavior was observed mainly at the beginning of alcohol hangover. These findings suggest that energy drink added to alcohol extends motor disabilities observed during an alcohol hangover episode in comparison with animals that received alcohol alone.

Collagen XI mutation lowers susceptibility to load-induced cartilage damage in mice

Interactions among risk factors for osteoarthritis (OA) are not well understood. We investigated the combined impact of two prevalent risk factors: mechanical loading and genetically abnormal cartilage tissue properties. We used cyclic tibial compression to simulate mechanical loading in the cho/+ (Col11a1 haploinsufficient) mouse, which has abnormal collagen fibrils in cartilage due to a point mutation in the Col11a1 gene. We hypothesized that the mutant collagen would not alter phenotypic bone properties and that cho/+ mice, which develop early onset OA, would develop enhanced load-induced cartilage damage compared to their littermates. To test our hypotheses, we applied cyclic compression to the left tibiae of 6-month-old cho/+ male mice and wild-type (WT) littermates for 1, 2, and 6 weeks at moderate (4.5 N) and high (9.0 N) peak load magnitudes. We then characterized load-induced cartilage and bone changes by histology, microcomputed tomography, and immunohistochemistry. Prior to loading, cho/+ mice had less dense, thinner cortical bone compared to WT littermates. In addition, in loaded and non-loaded limbs, cho/+ mice had thicker cartilage. With high loads, cho/+ mice experienced less load-induced cartilage damage at all time points and displayed decreased matrix metalloproteinase (MMP)-13 levels compared to WT littermates. The thinner, less dense cortical bone and thicker cartilage were unexpected and may have contributed to the reduced severity of load-induced cartilage damage in cho/+ mice. Furthermore, the spontaneous proteoglycan loss resulting from the mutant collagen XI was not additive to cartilage damage from mechanical loading, suggesting that these risk factors act through independent pathways. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:711-720, 2018.

Previous physical exercise alters the hepatic profile of oxidative-inflammatory status and limits the secondary brain damage induced by severe traumatic brain injury in rats

KEY POINTS

An early inflammatory response and oxidative stress are implicated in the signal transduction that alters both hepatic redox status and mitochondrial function after traumatic brain injury (TBI). Peripheral oxidative/inflammatory responses contribute to neuronal dysfunction after TBI Exercise training alters the profile of oxidative-inflammatory status in liver and protects against acute hyperglycaemia and a cerebral inflammatory response after TBI. Approaches such as exercise training, which attenuates neuronal damage after TBI, may have therapeutic potential through modulation of responses by metabolic organs. The vulnerability of the body to oxidative/inflammatory in TBI is significantly enhanced in sedentary compared to physically active counterparts.

ABSTRACT

Although systemic responses have been described after traumatic brain injury (TBI), little is known regarding potential interactions between brain and peripheral organs after neuronal injury. Accordingly, we aimed to investigate whether a peripheral oxidative/inflammatory response contributes to neuronal dysfunction after TBI, as well as the prophylactic role of exercise training. Animals were submitted to fluid percussion injury after 6 weeks of swimming training. Previous exercise training increased mRNA expression of X receptor alpha and ATP-binding cassette transporter, and decreased inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor (TNF)-α and interleukin (IL)-6 expression per se in liver. Interestingly, exercise training protected against hepatic inflammation (COX-2, iNOS, TNF-α and IL-6), oxidative stress (decreases in non-protein sulfhydryl and glutathione, as well as increases in 2',7'-dichlorofluorescein diacetate oxidation and protein carbonyl), which altered hepatic redox status (increases in myeloperoxidase and superoxide dismutase activity, as well as inhibition of catalase activity) mitochondrial function (decreases in methyl-tetrazolium and Δψ, as well as inhibition of citrate synthase activity) and ion gradient homeostasis (inhibition of Na⁺ ,K⁺ -ATPase activity inhibition) when analysed 24 h after TBI. Previous exercise training also protected against dysglycaemia, impaired hepatic signalling (increase in phosphorylated c-Jun NH2-terminal kinase, phosphorylated decreases in insulin receptor substrate and phosphorylated AKT expression), high levels of circulating and neuronal cytokines, the opening of the blood-brain barrier, neutrophil infiltration and Na⁺ ,K⁺ -ATPase activity inhibition in the ipsilateral cortex after TBI. Moreover, the impairment of protein function, neurobehavioural (neuromotor dysfunction and spatial learning) disability and hippocampal cell damage in sedentary rats suggests that exercise training also modulates peripheral oxidative/inflammatory pathways in TBI, which corroborates the ever increasing evidence regarding health-related outcomes with respect to a physically active lifestyle.

Moderate Exercise Allows for shorter Recovery Time in Critical Limb Ischemia

Whether and how moderate exercise might allow for accelerated limb recovery in chronic critical limb ischemia (CLI) remains to be determined. Chronic CLI was surgically induced in mice, and the effect of moderate exercise (training five times per week over a 3-week period) was investigated. Tissue damages and functional scores were assessed on the 4th, 6th, 10th, 20th, and 30th day after surgery. Mice were sacrificed 48 h after the last exercise session in order to assess muscle structure, mitochondrial respiration, calcium retention capacity, oxidative stress and transcript levels of genes encoding proteins controlling mitochondrial functions (PGC1α, PGC1β, NRF1) and anti-oxidant defenses markers (SOD1, SOD2, catalase). CLI resulted in tissue damages and impaired functional scores. Mitochondrial respiration and calcium retention capacity were decreased in the ischemic limb of the non-exercised group (V_max = 7.11 ± 1.14 vs. 9.86 ± 0.86 mmol 02/min/g dw, p < 0.001; CRC = 7.01 ± 0.97 vs. 11.96 ± 0.92 microM/mg dw, p < 0.001, respectively). Moderate exercise reduced tissue damages, improved functional scores, and restored mitochondrial respiration and calcium retention capacity in the ischemic limb (V_max = 9.75 ± 1.00 vs. 9.82 ± 0.68 mmol 02/min/g dw; CRC = 11.36 ± 1.33 vs. 12.01 ± 1.24 microM/mg dw, respectively). Exercise also enhanced the transcript levels of PGC1α, PGC1β, NRF1, as well as SOD1, SOD2, and catalase. Moderate exercise restores mitochondrial respiration and calcium retention capacity, and it has beneficial functional effects in chronic CLI, likely by stimulating reactive oxygen species-induced biogenesis and anti-oxidant defenses. These data support further development of exercise therapy even in advanced peripheral arterial disease.

Endurance exercise and gut microbiota: A review

BACKGROUND

The physiological and biochemical demands of intense exercise elicit both muscle-based and systemic responses. The main adaptations to endurance exercise include the correction of electrolyte imbalance, a decrease in glycogen storage and the increase of oxidative stress, intestinal permeability, muscle damage, and systemic inflammatory response. Adaptations to exercise might be influenced by the gut microbiota, which plays an important role in the production, storage, and expenditure of energy obtained from the diet as well as in inflammation, redox reactions, and hydration status.

METHODS

A systematic and comprehensive search of electronic databases, including MEDLINE, Scopus, ClinicalTrials.gov, ScienceDirect, Springer Link, and EMBASE was done. The search process was completed using the keywords: "endurance", "exercise", "immune response", "microbiota", "nutrition", and "probiotics".

RESULTS

Reviewed literature supports the hypothesis that intestinal microbiota might be able to provide a measureable, effective marker of an athlete's immune function and that microbial composition analysis might also be sensitive enough to detect exercise-induced stress and metabolic disorders. The review also supports the hypothesis that modifying the microbiota through the use of probiotics could be an important therapeutic tool to improve athletes' overall general health, performance, and energy availability while controlling inflammation and redox levels.

CONCLUSION

The present review provides a comprehensive overview of how gut microbiota may have a key role in controlling the oxidative stress and inflammatory responses as well as improving metabolism and energy expenditure during intense exercise.

The influence of vitamins E and C and exercise on brain aging

Age-related declines in motor and cognitive function have been associated with increases in oxidative stress. Accordingly, interventions capable of reducing the oxidative burden would be capable of preventing or reducing functional declines occurring during aging. Popular interventions such as antioxidant intake and moderate exercise are often recommended to attain healthy aging and have the capacity to alter redox burden. This review is intended to summarize the outcomes of antioxidant supplementation (more specifically of vitamins C and E) and exercise training on motor and cognitive declines during aging, and on measures of oxidative stress. Additionally, we will address whether co-implementation of these two types of interventions can potentially further their individual benefits. Together, these studies highlight the importance of using translationally-relevant parameters for interventions and to study their combined outcomes on healthy brain aging.

Silvering and swimming effects on aerobic metabolism and reactive oxygen species in the European eel

Silvering, the last metamorphosis in the eel life cycle induces morphological and physiological modifications in yellow eels (sedentary stage). It pre-adapts them to cope with the extreme conditions they will encounter during their 6000-km spawning migration. A previous study showed that silver eels are able to cope with reactive oxygen species (ROS) over-production linked to an increase in aerobic metabolism during sustained swimming, but the question remains as to whether this mechanism is associated with silvering. A sustained swimming session decreased red muscle in vitro mitochondrial oxygen consumption (MO₂) but increased ROS production in both eel stages. The swimming exercise used here was perhaps too intense to induce a stimulation of mitochondrial function or biogenesis even when antioxidant enzyme activities were unchanged. Pro-oxidant/antioxidant imbalance by lipid peroxidation increased in yellow but significantly decreased in silver eels. The silvering process therefore appears to allow a pre-adaptation of red muscle radical metabolism to the demands of spawning migration.

Relationships Between Mitochondria and Neuroinflammation: Implications for Alzheimer's Disease

Mitochondrial dysfunction and neuroinflammation occur in Alzheimer's disease (AD). The causes of these pathologic lesions remain uncertain, but links between these phenomena are increasingly recognized. In this review, we discuss data that indicate mitochondria or mitochondrial components may contribute to neuroinflammation. While mitochondrial dysfunction could cause neuroinflammation, neuroinflammation could also cause mitochondrial dysfunction. However, based on the systemic nature of AD mitochondrial dysfunction as well as data from experiments we discuss, the former possibility is perhaps more likely. If correct, then manipulation of mitochondria, either directly or through manipulations of bioenergetic pathways, could prove effective in reducing metabolic dysfunction and neuroinflammation in AD patients. We also review some potential approaches through which such manipulations may be achieved.

The potential of endurance exercise-derived exosomes to treat metabolic diseases

Endurance exercise-mediated multisystemic adaptations are known to mitigate metabolism-related disorders such as obesity and type 2 diabetes mellitus (T2DM). However, the underlying molecular mechanisms that promote crosstalk between organs and orchestrate the pro-metabolic effects of endurance exercise remain unclear. Exercise-induced release of peptides and nucleic acids from skeletal muscle and other organs (collectively termed 'exerkines') has been implicated in mediating these systemic adaptations. Given that the extracellular milieu is probably not a hospitable environment for labile exerkines, a lipid vehicle-based mode of delivery has originated over the course of evolution. Two types of extracellular vesicles, exosomes and microvesicles, have been shown to contain proteins and nucleic acids that participate in a variety of physiological and pathological processes. Exosomes, in particular, have been shown to facilitate the exchange of peptides, microRNA, mRNA and mitochondrial DNA between cells and tissues. Intriguingly, circulatory extracellular vesicle content increases in an intensity-dependant manner in response to endurance exercise. We propose that the systemic benefits of exercise are modulated by exosomes and/or microvesicles functioning in an autocrine, paracrine and/or endocrine manner. Furthermore, we posit that native or modified exosomes, and/or microvesicles enriched with exerkines will have therapeutic utility in the treatment of obesity and T2DM.

Integrated mRNA and miRNA expression profiling in blood reveals candidate biomarkers associated with endurance exercise in the horse

The adaptive response to extreme endurance exercise might involve transcriptional and translational regulation by microRNAs (miRNAs). Therefore, the objective of the present study was to perform an integrated analysis of the blood transcriptome and miRNome (using microarrays) in the horse before and after a 160 km endurance competition. A total of 2,453 differentially expressed genes and 167 differentially expressed microRNAs were identified when comparing pre- and post-ride samples. We used a hypergeometric test and its generalization to gain a better understanding of the biological functions regulated by the differentially expressed microRNA. In particular, 44 differentially expressed microRNAs putatively regulated a total of 351 depleted differentially expressed genes involved variously in glucose metabolism, fatty acid oxidation, mitochondrion biogenesis, and immune response pathways. In an independent validation set of animals, graphical Gaussian models confirmed that miR-21-5p, miR-181b-5p and miR-505-5p are candidate regulatory molecules for the adaptation to endurance exercise in the horse. To the best of our knowledge, the present study is the first to provide a comprehensive, integrated overview of the microRNA-mRNA co-regulation networks that may have a key role in controlling post-transcriptomic regulation during endurance exercise.

Exercise Modulates Oxidative Stress and Inflammation in Aging and Cardiovascular Diseases

Despite the wealth of epidemiological and experimental studies indicating the protective role of regular physical activity/exercise training against the sequels of aging and cardiovascular diseases, the molecular transducers of exercise/physical activity benefits are not fully identified but should be further investigated in more integrative and innovative approaches, as they bear the potential for transformative discoveries of novel therapeutic targets. As aging and cardiovascular diseases are associated with a chronic state of oxidative stress and inflammation mediated via complex and interconnected pathways, we will focus in this review on the antioxidant and anti-inflammatory actions of exercise, mainly exerted on adipose tissue, skeletal muscles, immune system, and cardiovascular system by modulating anti-inflammatory/proinflammatory cytokines profile, redox-sensitive transcription factors such as nuclear factor kappa B, activator protein-1, and peroxisome proliferator-activated receptor gamma coactivator 1-alpha, antioxidant and prooxidant enzymes, and repair proteins such as heat shock proteins, proteasome complex, oxoguanine DNA glycosylase, uracil DNA glycosylase, and telomerase. It is important to note that the effects of exercise vary depending on the type, intensity, frequency, and duration of exercise as well as on the individual's characteristics; therefore, the development of personalized exercise programs is essential.

Modulation of Hypercholesterolemia-Induced Oxidative/Nitrative Stress in the Heart

Hypercholesterolemia is a frequent metabolic disorder associated with increased risk for cardiovascular morbidity and mortality. In addition to its well-known proatherogenic effect, hypercholesterolemia may exert direct effects on the myocardium resulting in contractile dysfunction, aggravated ischemia/reperfusion injury, and diminished stress adaptation. Both preclinical and clinical studies suggested that elevated oxidative and/or nitrative stress plays a key role in cardiac complications induced by hypercholesterolemia. Therefore, modulation of hypercholesterolemia-induced myocardial oxidative/nitrative stress is a feasible approach to prevent or treat deleterious cardiac consequences. In this review, we discuss the effects of various pharmaceuticals, nutraceuticals, some novel potential pharmacological approaches, and physical exercise on hypercholesterolemia-induced oxidative/nitrative stress and subsequent cardiac dysfunction as well as impaired ischemic stress adaptation of the heart in hypercholesterolemia.

Physical exercise mitigates doxorubicin-induced brain cortex and cerebellum mitochondrial alterations and cellular quality control signaling

Doxorubicin (DOX) is a highly effective anti-neoplastic agent, whose clinical use is limited by a dose-dependent mitochondrial toxicity in non-target tissues, including the brain. Here we analyzed the effects of distinct exercise modalities (12-week endurance treadmill-TM or voluntary free-wheel activity-FW) performed before and during sub-chronic DOX treatment on brain cortex and cerebellum mitochondrial bioenergetics, oxidative stress, permeability transition pore (mPTP), and proteins involved in mitochondrial biogenesis, apoptosis and auto(mito)phagy. Male Sprague-Dawley rats were divided into saline-sedentary (SAL+SED), DOX-sedentary (DOX+SED; 7-week DOX (2 mg · kg(-1)per week)), DOX+TM and DOX+FW. Animal behavior and post-sacrifice mitochondrial function were assessed. Oxidative phosphorylation (OXPHOS) subunits, oxidative stress markers or related proteins (SIRT3, p66shc, UCP2, carbonyls, MDA, -SH, aconitase, Mn-SOD), as well as proteins involved in mitochondrial biogenesis (PGC1α and TFAM) were evaluated. Apoptotic signaling was followed through caspases 3, 8 and 9-like activities, Bax, Bcl2, CypD, ANT and cofilin expression. Mitochondrial dynamics (Mfn1, Mfn2, OPA1 and DRP1) and auto(mito)phagy (LC3II, Beclin1, Pink1, Parkin and p62)-related proteins were measured by semi-quantitative Western blotting. DOX impaired behavioral performance, mitochondrial function, including lower resistance to mPTP and increased apoptotic signaling, decreased the content in OXPHOS complex subunits and increased oxidative stress in brain cortex and cerebellum. Molecular markers of mitochondrial biogenesis, dynamics and autophagy were also altered by DOX treatment in both brain subareas. Generally, TM and FW were able to mitigate DOX-related impairments in brain cortex and cerebellum mitochondrial activity, mPTP and apoptotic signaling. We conclude that the alterations in mitochondrial biogenesis, dynamics and autophagy markers induced by exercise performed before and during treatment may contribute to the observed protective brain cortex and cerebellum mitochondrial phenotype, which is more resistant to oxidative damage and apoptotic signaling in sub-chronically DOX treated animals.

Understanding the Cellular and Molecular Mechanisms of Physical Activity-Induced Health Benefits

The beneficial effects of physical activity (PA) are well documented, yet the mechanisms by which PA prevents disease and improves health outcomes are poorly understood. To identify major gaps in knowledge and potential strategies for catalyzing progress in the field, the NIH convened a workshop in late October 2014 entitled "Understanding the Cellular and Molecular Mechanisms of Physical Activity-Induced Health Benefits." Presentations and discussions emphasized the challenges imposed by the integrative and intermittent nature of PA, the tremendous discovery potential of applying "-omics" technologies to understand interorgan crosstalk and biological networking systems during PA, and the need to establish an infrastructure of clinical trial sites with sufficient expertise to incorporate mechanistic outcome measures into adequately sized human PA trials. Identification of the mechanisms that underlie the link between PA and improved health holds extraordinary promise for discovery of novel therapeutic targets and development of personalized exercise medicine.

Improvement of the physical performance is associated with activation of NO/PGC-1α/mtTFA signaling pathway and increased protein expressions of electron transport chain in gastrocnemius muscle from rats supplemented with L-arginine

AIM

To examine the influence of l-arginine supplementation in combination with physical training on mitochondrial biomarkers from gastrocnemius muscle and its relationship with physical performance.

MAIN METHODS

Male Wistar rats were divided into four groups: control sedentary (SD), sedentary supplemented with l-arginine (SDLA), trained (TR) and trained supplemented with l-arginine (TRLA). Supplementation of l-arginine was administered by gavage (62.5mg/ml/day/rat). Physical training consisted of 60min/day, 5days/week, 0% grade, speed of 1.2km/h. The study lasted 8weeks. Skeletal muscle mitochondrial enriched fraction as well as cytoplasmic fractions were obtained for Western blotting and biochemical analyses. Protein expressions of transcriptor coactivator (PGC-1α), transcriptor factors (mtTFA), ATP synthase subunit c, cytochrome oxidase (COXIV), constitutive nitric oxide synthases (eNOS and nNOS), Cu/Zn-superoxide dismutase (SOD) and manganese-SOD (Mn-SOD) were evaluated. We also assessed in plasma: lipid profile, glycemia and malondialdehyde (MDA) levels. The nitrite/nitrate (NOx(-)) levels were measured in both plasma and cytosol fraction of the gastrocnemius muscle.

KEY FINDINGS

8-week l-arginine supplementation associated with physical training was effective in promoting greater tolerance to exercise that was accompanied by up-regulation of the protein expressions of mtTFA, PGC-1α, ATP synthase subunit c, COXIV, Cu/Zn-SOD and Mn-SOD. The upstream pathway was associated with improvement of NO bioavailability, but not in NO production since no changes in nNOS or eNOS protein expressions were observed.

SIGNIFICANCE

This combination would be an alternative approach for preventing cardiometabolic diseases given that in overt diseases a profound impairment in the physical performance of the patients is observed.

Sestrin2, a Regulator of Thermogenesis and Mitohormesis in Brown Adipose Tissue

Sestrin2 is a stress-inducible protein that functions as an antioxidant and inhibitor of mTOR complex 1. In a recent study, we found that Sestrin2 overexpression in brown adipocytes interfered with normal metabolism by reducing mitochondrial respiration through the suppression of uncoupling protein 1 (UCP1) expression. The metabolic effects of Sestrin2 in brown adipocytes were dependent on its antioxidant activity, and chemical antioxidants produced similar effects in inhibiting UCP1-dependent thermogenesis. These observations suggest that low levels of reactive oxygen species (ROS) in brown adipocytes can actually be beneficial and necessary for proper metabolic homeostasis. In addition, considering that Sestrins are ROS inducible and perform ROS detoxifying as well as other metabolism-controlling functions, they are potential regulators of mitohormesis. This is a concept in which overall beneficial effects result from low-level oxidative stress stimuli, such as the ones induced by caloric restriction or physical exercise. In this perspective, we incorporate our recent insight obtained from the Sestrin2 study toward a better understanding of the relationship between ROS, Sestrin2, and mitochondrial metabolism in the context of brown adipocyte physiology.

Mitochondrial adaptations evoked with exercise are associated with a reduction in age-induced testicular atrophy in Fischer-344 rats

Mitochondrial dysfunction in various tissues has been associated with numerous conditions including aging. In testes, aging induces atrophy and a decline in male reproductive function but the involvement of mitochondria is not clear. The purpose of this study was to examine whether the mitochondrial profile differed with (1) aging, and (2) 10-weeks of treadmill exercise training, in the testes of young (6 month) and old (24 month) Fischer-344 (F344) animals. Old animals exhibited significant atrophy (30 % decline; P < 0.05) in testes compared to young animals. However, relative mitochondrial content was not reduced with age and this was consistent with the lack of change in the mitochondrial biogenesis regulator protein, peroxisome proliferator-activated receptor gamma coactivator 1-alpha and its downstream targets nuclear respiratory factor-1 and mitochondrial transcription factor A. No effect was observed in the pro- or anti-apoptotic proteins, Bax and Bcl-2, respectively, but age increased apoptosis inducing factor levels. Endurance training induced beneficial mitochondrial adaptations that were more prominent in old animals including greater increases in relative mtDNA content, biogenesis/remodeling (mitofusin 2), antioxidant capacity (mitochondrial superoxide dismutase) and lower levels of phosphorylated histone H2AX, an early marker of DNA damage (P < 0.05). Importantly, these exercise-induced changes were associated with an attenuation of testes atrophy in older sedentary animals (P < 0.05). Our results indicate that aging-induced atrophy in testes may not be associated with changes in relative mitochondrial content and key regulatory proteins and that exercise started in late-life elicits beneficial changes in mitochondria that may protect against age-induced testicular atrophy.

Exercise mitigates diclofenac-induced liver mitochondrial dysfunction

BACKGROUND

Several strategies have been developed to counteract liver injury as a consequence of nonsteroid anti-inflammatory drugs toxicity. Here, we aimed to determine whether physical exercise results in liver mitochondrial protection against in vitro diclofenac toxicity.

MATERIAL AND METHODS

Male adult Sprague-Dawley rats were divided into sedentary, 12-week endurance training (ET) and voluntary activity (VPA). In vitro liver mitochondrial function as assessed by oxygen consumption, transmembrane electric potential (ΔΨ) and susceptibility to the mitochondrial permeability transition pore (MPTP) was evaluated in the absence and presence of diclofenac. Mitochondrial oxidative stress markers [MnSOD, aconitase, -SH and MDA, SIRT3, p66shc(Ser36)/p66shc ratio] and apoptotic signalling (caspases 3, 8 and 9, Bax, Bcl-2 and CypD) were assessed. Content of OXPHOS components and qualitative liver morphological evaluation were assessed.

RESULTS

Despite no effects of ET and VPA on basal liver mitochondrial oxygen consumption or ΔΨ endpoints, exercised animals showed lower susceptibility to MPTP. Diclofenac-induced decrease in ΔΨ, increased state 4 respiration and susceptibility to MPTP opening were all prevented by exercise. Under untreated conditions, VPA group showed higher aconitase activity, while ET decreased MDA and increased Bax content. VPA decreased p66shc(Ser36), complex III and V OXPHOS subunits. Both ET and VPA increased complex IV OXPHOS subunit, and SIRT3 and Bcl-2 content and decreased caspase 9 activity. Unexpectedly, ET and VPA decreased ANT.

CONCLUSIONS

Both chronic physical exercise models augmented the resistance to in vitro diclofenac-induced mitochondrial alterations, including increased MPTP susceptibility, possibly by modulating oxidative stress and MPTP regulators.

Running wheel exercise before a binge regimen of methamphetamine does not protect against striatal dopaminergic damage

Repeated administration of methamphetamine (mAMPH) to rodents in a single-day "binge" dosing regimen produces long-lasting damage to forebrain dopaminergic nerve terminals as measured by decreases in tissue dopamine (DA) content and levels of the plasmalemmal DA transporter (DAT). However, the midbrain cell bodies from which the DA terminals arise survive, and previous reports show that striatal DA markers return to control levels by 12 months post-mAMPH, suggesting long-term repair or regrowth of damaged DA terminals. We previously showed that when rats engaged in voluntary aerobic exercise for 3 weeks before and 3 weeks after a binge regimen of mAMPH, exercise significantly ameliorated mAMPH-induced decreases in striatal DAT. However, these data left unresolved the question of whether exercise protected against the initial neurotoxicity from the mAMPH binge or accelerated the repair of the damaged DA terminals. The present experiments were designed to test whether exercise protects against the mAMPH-induced injury. Adult male Sprague-Dawley rats were allowed to run in wheels for 3 weeks before an acute binge regimen of mAMPH or saline, then placed into nonwheel cages for an additional week before autoradiographic determination of striatal DAT binding. The autoradiographic findings showed that prior exercise provided no protection against mAMPH-induced damage to striatal DA terminals. These results, together with analyses from our previous experiments, suggest that voluntary exercise may accelerate the repair of mAMPH-damaged DA terminals and that voluntary exercise may be useful as therapeutic adjunct in the treatment mAMPH addicts.

Effect of high-intensity exercise on aged mouse brain mitochondria, neurogenesis, and inflammation

In aged mice, we assessed how intensive exercise affects brain bioenergetics, inflammation, and neurogenesis-relevant parameters. After 8 weeks of a supra-lactate threshold treadmill exercise intervention, 21-month-old C57BL/6 mice showed increased brain peroxisome proliferator-activated receptor gamma coactivator-1α protein, mammalian target of rapamycin and phospho-mammalian target of rapamycin protein, citrate synthase messenger RNA, and mitochondrial DNA copy number. Hippocampal vascular endothelial growth factor A (VEGF-A) gene expression trended higher, and a positive correlation between VEGF-A and PRC messenger RNA levels was observed. Brain doublecortin, brain-derived neurotrophic factor, tumor necrosis factor-α, and CCL11 gene expression, as well as plasma CCL11 protein levels, were unchanged. Despite these apparent negative findings, a negative correlation between plasma CCL11 protein levels and hippocampal doublecortin gene expression was observed; further analysis indicated exercise may mitigate this relationship. Overall, our data suggest supra-lactate threshold exercise activates a partial mitochondrial biogenesis in aged mice, and a gene (VEGF-A) known to support neurogenesis. Our data are consistent with another study that found systemic inflammation in general, and CCL11 protein specifically, suppresses hippocampal neurogenesis. Our study supports the view that intense exercise above the lactate threshold may benefit the aging brain; future studies to address the extent to which exercise-generated lactate mediates the observed effects are warranted.

Mitohormesis: Promoting Health and Lifespan by Increased Levels of Reactive Oxygen Species (ROS)

Increasing evidence indicates that reactive oxygen species (ROS), consisting of superoxide, hydrogen peroxide, and multiple others, do not only cause oxidative stress, but rather may function as signaling molecules that promote health by preventing or delaying a number of chronic diseases, and ultimately extend lifespan. While high levels of ROS are generally accepted to cause cellular damage and to promote aging, low levels of these may rather improve systemic defense mechanisms by inducing an adaptive response. This concept has been named mitochondrial hormesis or mitohormesis. We here evaluate and summarize more than 500 publications from current literature regarding such ROS-mediated low-dose signaling events, including calorie restriction, hypoxia, temperature stress, and physical activity, as well as signaling events downstream of insulin/IGF-1 receptors, AMP-dependent kinase (AMPK), target-of-rapamycin (TOR), and lastly sirtuins to culminate in control of proteostasis, unfolded protein response (UPR), stem cell maintenance and stress resistance. Additionally, consequences of interfering with such ROS signals by pharmacological or natural compounds are being discussed, concluding that particularly antioxidants are useless or even harmful.