Exercise-induced cardioprotection--biochemical, morphological and functional evidence in whole tissue and isolated mitochondria

Mitochondrial Dysfunction in Cardiotoxicity Induced by BCR-ABL1 Tyrosine Kinase Inhibitors -Underlying Mechanisms, Detection, Potential Therapies

The advent of BCR-ABL tyrosine kinase inhibitors (TKIs) targeted therapy revolutionized the treatment of chronic myeloid leukemia (CML) patients. Mitochondria are the key organelles for the maintenance of myocardial tissue homeostasis. However, cardiotoxicity associated with BCR-ABL1 TKIs can directly or indirectly cause mitochondrial damage and dysfunction, playing a pivotal role in cardiomyocytes homeostatic system and putting the cancer survivors at higher risk. In this review, we summarize the cardiotoxicity caused by BCR-ABL1 TKIs and the underlying mechanisms, which contribute dominantly to the damage of mitochondrial structure and dysfunction: endoplasmic reticulum (ER) stress, mitochondrial stress, damage of myocardial cell mitochondrial respiratory chain, increased production of mitochondrial reactive oxygen species (ROS), and other kinases and other potential mechanisms of cardiotoxicity induced by BCR-ABL1 TKIs. Furthermore, detection and management of BCR-ABL1 TKIs will promote our rational use, and cardioprotection strategies based on mitochondria will improve our understanding of the cardiotoxicity from a mitochondrial perspective. Ultimately, we hope shed light on clinical decision-making. By integrate and learn from both research and practice, we will endeavor to minimize the mitochondria-mediated cardiotoxicity and reduce the adverse sequelae associated with BCR-ABL1 TKIs.

Myokine Musclin Is Critical for Exercise-Induced Cardiac Conditioning

This study investigates the role and mechanisms by which the myokine musclin promotes exercise-induced cardiac conditioning. Exercise is one of the most powerful triggers of cardiac conditioning with proven benefits for healthy and diseased hearts. There is an emerging understanding that muscles produce and secrete myokines, which mediate local and systemic "crosstalk" to promote exercise tolerance and overall health, including cardiac conditioning. The myokine musclin, highly conserved across animal species, has been shown to be upregulated in response to physical activity. However, musclin effects on exercise-induced cardiac conditioning are not established. Following completion of a treadmill exercise protocol, wild type (WT) mice and mice with disruption of the musclin-encoding gene, Ostn, had their hearts extracted and exposed to an ex vivo ischemia-reperfusion protocol or biochemical studies. Disruption of musclin signaling abolished the ability of exercise to mitigate cardiac ischemic injury. This impaired cardioprotection was associated with reduced mitochondrial content and function linked to blunted cyclic guanosine monophosphate (cGMP) signaling. Genetic deletion of musclin reduced the nuclear abundance of protein kinase G (PKGI) and cyclic adenosine monophosphate (cAMP) response element binding (CREB), resulting in suppression of the master regulator of mitochondrial biogenesis, peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α), and its downstream targets in response to physical activity. Synthetic musclin peptide pharmacokinetic parameters were defined and used to calculate the infusion rate necessary to maintain its plasma level comparable to that observed after exercise. This infusion was found to reproduce the cardioprotective benefits of exercise in sedentary WT and Ostn-KO mice. Musclin is essential for exercise-induced cardiac protection. Boosting musclin signaling might serve as a novel therapeutic strategy for cardioprotection.

The beneficial role of exercise in preventing doxorubicin-induced cardiotoxicity

Doxorubicin is a highly effective chemotherapeutic agent widely used to treat a variety of cancers. However, the clinical application of doxorubicin is limited due to its adverse effects on several tissues. One of the most serious side effects of doxorubicin is cardiotoxicity, which results in life-threatening heart damage, leading to reduced cancer treatment success and survival rate. Doxorubicin-induced cardiotoxicity results from cellular toxicity, including increased oxidative stress, apoptosis, and activated proteolytic systems. Exercise training has emerged as a non-pharmacological intervention to prevent cardiotoxicity during and after chemotherapy. Exercise training stimulates numerous physiological adaptations in the heart that promote cardioprotective effects against doxorubicin-induced cardiotoxicity. Understanding the mechanisms responsible for exercise-induced cardioprotection is important to develop therapeutic approaches for cancer patients and survivors. In this report, we review the cardiotoxic effects of doxorubicin and discuss the current understanding of exercise-induced cardioprotection in hearts from doxorubicin-treated animals.

The Beneficial Role of Physical Exercise on Anthracyclines Induced Cardiotoxicity in Breast Cancer Patients

The increase in breast cancer (BC) survival has determined a growing survivor population that seems to develop several comorbidities and, specifically, treatment-induced cardiovascular disease (CVD), especially those patients treated with anthracyclines. Indeed, it is known that these compounds act through the induction of supraphysiological production of reactive oxygen species (ROS), which appear to be central mediators of numerous direct and indirect cardiac adverse consequences. Evidence suggests that physical exercise (PE) practised before, during or after BC treatments could represent a viable non-pharmacological strategy as it increases heart tolerance against many cardiotoxic agents, and therefore improves several functional, subclinical, and clinical parameters. At molecular level, the cardioprotective effects are mainly associated with an exercise-induced increase of stress response proteins (HSP60 and HSP70) and antioxidant (SOD activity, GSH), as well as a decrease in lipid peroxidation, and pro-apoptotic proteins such as Bax, Bax-to-Bcl-2 ratio. Moreover, this protection can potentially be explained by a preservation of myosin heavy chain (MHC) isoform distribution. Despite this knowledge, it is not clear which type of exercise should be suggested in BC patient undergoing anthracycline treatment. This highlights the lack of special guidelines on how affected patients should be managed more efficiently. This review offers a general framework for the role of anthracyclines in the physio-pathological mechanisms of cardiotoxicity and the potential protective role of PE. Finally, potential exercise-based strategies are discussed on the basis of scientific findings.

Exercise Cardio-Oncology: Exercise as a Potential Therapeutic Modality in the Management of Anthracycline-Induced Cardiotoxicity

Anthracyclines are one of the most effective chemotherapy agents and have revolutionized cancer therapy. However, anthracyclines can induce cardiac injuries through ‘multiple-hits', a series of cardiovascular insults coupled with lifestyle risk factors, which increase the risk of developing short- and long-term cardiac dysfunction and cardiovascular disease that potentially lead to premature mortality following cancer remission. Therefore, the management of anthracycline-induced cardiotoxicity is a serious unmet clinical need. Exercise therapy, as a non-pharmacological intervention, stimulates numerous biochemical and physiologic adaptations, including cardioprotective effects, through the cardiovascular system and cardiac muscles, where exercise has been proposed to be an effective clinical approach that can protect or reverse the cardiotoxicity from anthracyclines. Many preclinical and clinical trials demonstrate the potential impacts of exercise on cardiotoxicity; however, the underlying mechanisms as well as how to implement exercise in clinical settings to improve or protect against long-term cardiovascular disease outcomes are not clearly defined. In this review, we summarize the current evidence in the field of “exercise cardio-oncology” and emphasize the utilization of exercise to prevent and manage anthracycline-induced cardiotoxicities across high-risk and vulnerable populations diagnosed with cancer.

Physical Exercise Promotes a Reduction in Cardiac Fibrosis in the Chronic Indeterminate Form of Experimental Chagas Disease

Chagas disease (CD), caused by the protozoan Trypanosoma cruzi, is a neglected tropical disease and a health problem in Latin America. Etiological treatment has limited effectiveness in chronic CD; thus, new therapeutic strategies are required. The practice of physical exercises has been widely advocated to improve the quality of life of CD patients. The most frequent clinical CD manifestation is the chronic indeterminate form (CIF), and the effect of physical exercises on disease progression remains unknown. Here, in a CIF model, we aimed to evaluate the effect of physical exercises on cardiac histological, parasitological, mitochondrial, and oxidative metabolism, electro and echocardiographic profiles, and immunological features. To establish a CIF model, BALB/c and C57BL/6 mice were infected with 100 and 500 trypomastigotes of the Y T. cruzi strain. At 120 days postinfection (dpi), all mouse groups showed normal PR and corrected QT intervals and QRS complexes. Compared to BALB/c mice, C57BL/6 mice showed a lower parasitemia peak, mortality rate, and less intense myocarditis. Thus, C57BL/6 mice infected with 500 parasites were used for subsequent analyses. At 120 dpi, a decrease in cardiac mitochondrial oxygen consumption and an increase in reactive oxygen species (ROS) were detected. When we increased the number of analyzed mice, a reduced heart rate and slightly prolonged corrected QT intervals were detected, at 120 and 150 dpi, which were then normalized at 180 dpi, thus characterizing the CIF. Y-infected mice were subjected to an exercise program on a treadmill for 4 weeks (from 150 to 180 dpi), five times per week in a 30–60-min daily training session. At 180 dpi, no alterations were detected in cardiac mitochondrial and oxidative metabolism, which were not affected by physical exercises, although ROS production increased. At 120 and 180 dpi, comparing infected and non-infected mice, no differences were observed in the levels of plasma cytokines, indicating that a crucial biomarker of the systemic inflammatory profile was absent and not affected by exercise. Compared with sedentary mice, trained Y-infected mice showed similar parasite loads and inflammatory cells but reduced cardiac fibrosis. Therefore, our data show that physical exercises promote beneficial changes that may prevent CD progression.

Sex-Specific Impacts of Exercise on Cardiovascular Remodeling

Cardiovascular diseases (CVD) remain the leading cause of death in men and women. Biological sex plays a major role in cardiovascular physiology and pathological cardiovascular remodeling. Traditionally, pathological remodeling of cardiovascular system refers to the molecular, cellular, and morphological changes that result from insults, such as myocardial infarction or hypertension. Regular exercise training is known to induce physiological cardiovascular remodeling and beneficial functional adaptation of the cardiovascular apparatus. However, impact of exercise-induced cardiovascular remodeling and functional adaptation varies between males and females. This review aims to compare and contrast sex-specific manifestations of exercise-induced cardiovascular remodeling and functional adaptation. Specifically, we review (1) sex disparities in cardiovascular function, (2) influence of biological sex on exercise-induced cardiovascular remodeling and functional adaptation, and (3) sex-specific impacts of various types, intensities, and durations of exercise training on cardiovascular apparatus. The review highlights both animal and human studies in order to give an all-encompassing view of the exercise-induced sex differences in cardiovascular system and addresses the gaps in knowledge in the field.

Exercise-Training Regulates Apolipoprotein B in Drosophila to Improve HFD-Mediated Cardiac Function Damage and Low Exercise Capacity

Apolipoprotein B plays an essential role in systemic lipid metabolism, and it is closely related to cardiovascular diseases. Exercise-training can regulate systemic lipid metabolism, improve heart function, and improve exercise capacity, but the molecular mechanisms involved are poorly understood. We used a Drosophila model to demonstrate that exercise-training regulates the expression of apoLpp (a homolog of apolipoprotein B) in cardiomyocytes, thereby resisting heart insufficiency and low exercise capacity caused by obesity. The apoLpp is an essential lipid carrier produced in the heart and fat body of Drosophila. In a Drosophila genetic screen, low expression of apoLpp reduced obesity and cardiac dysfunction induced by a high-fat diet (HFD). Cardiac-specific inhibition indicated that reducing apoLpp in the heart during HFD reduced the triglyceride content of the whole-body and reduced heart function damage caused by HFD. In exercise-trained flies, the result was similar to the knockdown effect of apoLpp. Therefore, the inhibition of apoLpp plays an important role in HFD-induced cardiac function impairment and low exercise capacity. Although the apoLpp knockdown of cardiomyocytes alleviated damage to heart function, it did not reduce the arrhythmia and low exercise capacity caused by HFD. Exercise-training can improve this condition more effectively, and the possible reason for this difference is that exercise-training regulates climbing ability in ways to promote metabolism. Exercise-training during HFD feeding can down-regulate the expression of apoLpp, reduce the whole-body TG levels, improve cardiac recovery, and improve exercise capacity. Exercise-training can downregulate the expression of apoLpp in cardiomyocytes to resist cardiac function damage and low exercise capacity caused by HFD. The results revealed the relationship between exercise-training and apoLpp and their essential roles in regulating heart function and climbing ability.

Longitudinal Associations of Fitness and Obesity in Young Adulthood With Right Ventricular Function and Pulmonary Artery Systolic Pressure in Middle Age: The CARDIA Study

Background Low cardiorespiratory fitness (CRF) and obesity are risk factors for heart failure but their associations with right ventricular (RV) systolic function and pulmonary artery systolic pressure (PASP) are not well understood. Methods and Results Participants in the CARDIA (Coronary Artery Risk Development in Young Adults) study who underwent maximal treadmill testing at baseline and had a follow-up echocardiographic examination at year 25 were included. A subset of participants had repeat CRF and body mass index (BMI) assessment at year 20. The associations of baseline and changes in CRF and BMI on follow-up (baseline to year 20) with RV systolic function parameters (tricuspid annular plane systolic excursion, RV Doppler systolic velocity of the lateral tricuspid annulus), and PASP were assessed using multivariable-adjusted linear regression models. The study included 3433 participants. In adjusted analysis, higher baseline BMI but not CRF was significantly associated with higher PASP. Among RV systolic function parameters, higher baseline CRF and BMI were significantly associated with higher tricuspid annular plane systolic excursion and RV systolic velocity of the lateral tricuspid annulus. In the subgroup of participants with follow-up assessment of CRF or BMI at year 20, less decline in CRF was associated with higher RV systolic velocity of the lateral tricuspid annulus and lower PASP, while greater increase in BMI was significantly associated with higher PASP in middle age. Conclusions Higher CRF in young adulthood and less decline in CRF over time are each significantly associated with better RV systolic function. Higher baseline BMI and greater age-related increases in BMI are each significantly associated with higher PASP in middle age. These findings provide insights into possible mechanisms through which low fitness and obesity may contribute toward risk of heart failure.

Quality Matters? The Involvement of Mitochondrial Quality Control in Cardiovascular Disease

Cardiovascular diseases are one of the leading causes of death and global health problems worldwide. Multiple factors are known to affect the cardiovascular system from lifestyles, genes, underlying comorbidities, and age. Requiring high workload, metabolism of the heart is largely dependent on continuous power supply via mitochondria through effective oxidative respiration. Mitochondria not only serve as cellular power plants, but are also involved in many critical cellular processes, including the generation of intracellular reactive oxygen species (ROS) and regulating cellular survival. To cope with environmental stress, mitochondrial function has been suggested to be essential during bioenergetics adaptation resulting in cardiac pathological remodeling. Thus, mitochondrial dysfunction has been advocated in various aspects of cardiovascular pathology including the response to ischemia/reperfusion (I/R) injury, hypertension (HTN), and cardiovascular complications related to type 2 diabetes mellitus (DM). Therefore, mitochondrial homeostasis through mitochondrial dynamics and quality control is pivotal in the maintenance of cardiac health. Impairment of the segregation of damaged components and degradation of unhealthy mitochondria through autophagic mechanisms may play a crucial role in the pathogenesis of various cardiac disorders. This article provides in-depth understanding of the current literature regarding mitochondrial remodeling and dynamics in cardiovascular diseases.

Cardiac up-regulation of NBCe1 emerges as a beneficial consequence of voluntary wheel running in mice

Physical training stimulates the development of physiologic cardiac hypertrophy (CH), being a key event in this process the inhibition of the Na⁺/H⁺ exchanger. However, the role of the sodium bicarbonate cotransporter (NBC) has not been explored yet under this circumstance. C57/Bl6 mice were allowed to voluntary exercise (wheel running) for five weeks. Cardiac mass was evaluated by echocardiography and histomorphometry detecting that training promoted the development of physiological CH (heart weight/tibia length ratio, mg/mm: 6.54 ± 0.20 vs 8.81 ± 0.24; interstitial collagen content, %: 3.14 ± 0.63 vs. 1.57 ± 0.27; and cross-sectional area of cardiomyocytes, μm²: 200.6 ± 8.92 vs. 281.9 ± 24.05; sedentary (Sed) and exercised (Ex) mice, respectively). The activity of the electrogenic isoform of the cardiac NBC (NBCe1) was estimated by recording intracellular pH under high potassium concentration and by measuring action potential duration (APD). NBCe1 activity was significantly increased in isolated cardiomyocytes of trained mice. Additionally, the APD was shorter and the alkalization due to high extracellular potassium-induced depolarization was greater in this group, indicating that the NBCe1 was hyperactive. These results are online with the observed myocardial up-regulation of the NBCe1 (Western Blot, %: 100 ± 13.86 vs. 202 ± 29.98; Sed vs. Ex, n = 6 each group). In addition, we detected a reduction in H₂O₂ production in the myocardium of trained mice. These results support that voluntary training induces the development of physiologic CH with up-regulation of the cardiac NBCe1 in mice. Furthermore, the improvement in the antioxidant capacity contributes to the beneficial cardiovascular consequences of physical training.

Hemodynamics in young athletes following high-intensity interval or moderate-intensity continuous training

BACKGROUND

The present study aimed to investigate the effects of high-intensity interval training (HIIT) versus moderate-intensity continuous training (MICT) on blood pressure (BP) and parameters of arterial stiffness in young athletes.

METHODS

Seventeen rowers (aged 15±1.3 years) were randomized into an intervention group (IG, N.=10) and the control group (CG, N.=7). During an 8-week intervention period, the IG completed a HIIT on the rowing ergometer twice-weekly (2×4×2 min at ≈95% of maximum heart rate [HR<inf>max</inf>], 60 s rest) in addition to the regular rowing training (3×/week MICT 70-90 min, ≈70% HR<inf>max</inf>). The CG completed the regular normal rowing training and, instead of the HIIT units, two additional MICT units (70-90 min, ≈70% HR<inf>max</inf>). Before and after the intervention period, hemodynamic parameters were recorded non-invasively in both groups.

RESULTS

After the intervention period, there was a significant decrease in peripheral systolic (P=0.01) and diastolic (P=0.05) BP, as well as in central systolic (P=0.05) and diastolic BP (P=0.03) in the IG. Furthermore, pulse wave velocity (PWV) (P=0.05) was significantly reduced. Analysis of intervention effects revealed significant between-group differences in central diastolic BP (P=0.05), in augmentation pressure (P=0.02), and in augmentation index (P=0.006) favoring IG. The CG showed no significant changes in the respected parameters throughout the intervention.

CONCLUSIONS

Already in adolescent athletes, a HIIT intervention has beneficial effects on peripheral and central BP as well as on PWV, augmentation pressure, and augmentation index.

Redox Homeostasis in Humans Exposed to Intermittent Hypoxia-Normoxia and to Intermittent Hypoxia-Hyperoxia

Aim: Exposure to hypoxia is known to increase oxidative stress and to impair antioxidant defenses in humans. The aim of the study was to measure oxidative stress and antioxidant capacity in healthy humans after being acutely exposed to both intermittent hypoxia-normoxia (IHN) and intermittent hypoxia-hyperoxia (IHH). Methods: Twenty-one healthy, young male participants were exposed to both IHN and IHH (fraction of inspired oxygen [FIO₂] 0.11 for up to 7 minutes followed by 3-5 minutes of exposure to normoxia (room air) or hyperoxia, FIO₂ 0.3-0.35) in a crossover design study. In each participant, oxidative stress and antioxidant capacity were measured before and after each exposure in both experimental conditions. Results: After IHN, compared with baseline, neither oxidative stress (289.1 ± 63.2 vs. 262.2 ± 85.2 UCarr) nor antioxidant capacity (2376.1 ± 452.9 vs. 2525.0 ± 400.7 UCor) was significantly different. After IHH, neither oxidative stress (285.1 ± 94.2 vs. 277.5 ± 86.7 UCarr) nor antioxidant capacity (2653.6 ± 492.7 vs. 2568.4 ± 427.4 UCor) was significantly different compared with baseline. When the two studied exposure modalities were compared, there was no significant difference between groups with respect to both oxidative stress and antioxidant capacity. Conclusions: These data suggest that exposing healthy individuals to short-term IHN and IHH does not increase oxidative stress and it does not impair antioxidant defenses.

Exercise and Doxorubicin Treatment Modulate Cardiac Mitochondrial Quality Control Signaling

The cross-tolerance effect of exercise against heart mitochondrial-mediated quality control, remodeling and death-related mechanisms associated with sub-chronic Doxorubicin (DOX) treatment is yet unknown. We therefore analyzed the effects of two distinct chronic exercise models (endurance treadmill training-TM and voluntary free wheel activity-FW) performed during the course of the sub-chronic DOX treatment on mitochondrial susceptibility to permeability transition pore (mPTP), apoptotic and autophagic signaling and mitochondrial dynamics. Male Sprague-Dawley rats were divided into six groups (n = 6 per group): saline sedentary (SAL + SED), SAL + TM (12-weeks treadmill), SAL + FW (12-weeks voluntary free-wheel), DOX + SED [7-weeks sub-chronic DOX treatment (2 mg kg^-1 week^-1)], DOX + TM and DOX + FW. Apoptotic signaling and mPTP regulation were followed by measuring caspase 3, 8 and 9 activities, Bax, Bcl2, CypD, ANT, and cophilin expression. Mitochondrial dynamics (Mfn1, Mfn2, OPA1 and DRP1) and auto(mito)phagy (LC3, Beclin1, Pink1, Parkin and p62)-related proteins were semi-quantified. DOX treatment results in augmented mPTP susceptibility and apoptotic signaling (caspases 3, 8 and 9 and Bax/Bcl2 ratio). Moreover, DOX decreased the expression of fusion-related proteins (Mfn1, Mfn2, OPA1), increased DRP1 and the activation of auto(mito)phagy signaling. TM and FW prevented DOX-increased mPTP susceptibility and apoptotic signaling, alterations in mitochondrial dynamics and inhibits DOX-induced increases in auto(mito)phagy signaling. Collectively, our results suggest that both used chronic exercise models performed before and during the course of sub-chronic DOX treatment limit cardiac mitochondrial-driven apoptotic signaling and regulate alterations in mitochondrial dynamics and auto(mito)phagy in DOX-treated animals.

Sugar or fat: The metabolic choice of the trained heart

Mammals respond to muscular exercise by increasing cardiac output to meet the increased demand for oxygen in the working muscles and it is well-established that regular bouts of exercise results in myocardial remodeling. Depending on exercise type, intensity and duration, these cardiac adaptations lead to changes in the energetic substrates required to sustain cardiac contractility. In contrast to the failing heart, fatty acids are the preferred substrate in the trained heart, though glucose metabolism is also enhanced to support oxidative phosphorylation. The participation of AMPK/eNOS and PPARα/PGC-1α pathways in the regulation of cardiac metabolism is well known but other players also contribute including sirtuins and integrins-mediated outside-in activation of FAK and other kinases. These regulatory players act by up-regulating fatty acid uptake, transport to mitochondria and oxidation, and glucose uptake via GLUT4. This exercise-induced increase in mitochondria metabolic flexibility is important to sustain the energetic demand associated with cardiomyocyte hypertrophy and hyperplasia promoted by IGF-1 and neuregulin-1-induced PI3K/Akt signaling. So, the timeless advice of Hippocrates "walking is the best medicine" seems to be justified by the promotion of mitochondrial health and, consequently, the beneficial metabolic remodeling of the heart.

Fetal growth restriction shortens cardiac telomere length, but this is attenuated by exercise in early life

BACKGROUND AND AIMS

Fetal and postnatal growth restriction cause a predisposition to cardiovascular disease (CVD) in adulthood. Telomeres are repetitive DNA-protein structures that protect chromosome ends, and the loss of these repeats (a reduction in telomere length) is associated with CVD. As exercise preserves telomere length and cardiovascular health, the aim of this study was to determine the effects of growth restriction and exercise training on cardiac telomere length and telomeric genes.

METHODS AND RESULTS

Pregnant Wistar Kyoto rats underwent bilateral uterine vessel ligation to induce uteroplacental insufficiency and fetal growth restriction ("Restricted"). Sham-operated rats had either intact litters ("Control") or their litters reduced to five pups with slowed postnatal growth ("Reduced"). Control, Restricted, and Reduced male rats were assigned to Sedentary, Early exercise (5-9 wk of age), or Late exercise (20-24 wk of age) groups. Hearts were excised at 24 wk of age for telomere length and gene expression measurements by quantitative PCR. Growth restriction shortened cardiac telomere length ( P < 0.001), but this was rescued by early exercise ( P < 0.001). Early and Late exercise increased cardiac weight index ( P < 0.001), but neither this nor telomere length was associated with expression of the telomeric genes Tert, Terc, Trf2, Pnuts, or Sirt1.

DISCUSSION AND CONCLUSIONS

Growth restriction shortens cardiac telomere length, reflecting the cardiac pathologies associated with low birth weight. Exercise in early life may offer long-term protective effects on cardiac telomere length, which could help prevent CVD in later life.

Octopamine Drives Endurance Exercise Adaptations in Drosophila

Endurance exercise is an effective therapeutic intervention with substantial pro-healthspan effects. Male Drosophila respond to a ramped daily program of exercise by inducing conserved physiological responses similar to those seen in mice and humans. Female flies respond to an exercise stimulus but do not experience the adaptive training response seen in males. Here, we use female flies as a model to demonstrate that differences in exercise response are mediated by differences in neuronal activity. The activity of octopaminergic neurons is specifically required to induce the conserved cellular and physiological changes seen following endurance training. Furthermore, either intermittent, scheduled activation of octopaminergic neurons or octopamine feeding is able to fully substitute for exercise, conferring a suite of pro-healthspan benefits to sedentary Drosophila. These experiments indicate that octopamine is a critical mediator of adaptation to endurance exercise in Drosophila.

Chemotherapeutic Drugs and Mitochondrial Dysfunction: Focus on Doxorubicin, Trastuzumab, and Sunitinib

Many cancer therapies produce toxic side effects whose molecular mechanisms await full elucidation. The most feared and studied side effect of chemotherapeutic drugs is cardiotoxicity. Also, skeletal muscle physiology impairment has been recorded after many chemotherapeutical treatments. However, only doxorubicin has been extensively studied for its side effects on skeletal muscle. Chemotherapeutic-induced adverse side effects are, in many cases, mediated by mitochondrial damage. In particular, trastuzumab and sunitinib toxicity is mainly associated with mitochondria impairment and is mostly reversible. Vice versa, doxorubicin-induced toxicity not only includes mitochondria damage but can also lead to a more robust and extensive cell injury which is often irreversible and lethal. Drugs interfering with mitochondrial functionality determine the depletion of ATP reservoirs and lead to subsequent reversible contractile dysfunction. Mitochondrial damage includes the impairment of the respiratory chain and the loss of mitochondrial membrane potential with subsequent disruption of cellular energetic. In a context of increased stress, AMPK has a key role in maintaining energy homeostasis, and inhibition of the AMPK pathway is one of the proposed mechanisms possibly mediating mitochondrial toxicity due to chemotherapeutics. Therapies targeting and protecting cell metabolism and energy management might be useful tools in protecting muscular tissues against the toxicity induced by chemotherapeutic drugs.

The beneficial role of exercise in mitigating doxorubicin-induced Mitochondrionopathy

Doxorubicin (DOX) is a widely used antineoplastic agent for a wide range of cancers, including hematological malignancies, soft tissue sarcomas and solid tumors. However, DOX exhibits a dose-related toxicity that results in life-threatening cardiomyopathy. In addition to the heart, there is evidence that DOX toxicity extends to other organs. This general toxicity seems to be related to mitochondrial network structural, molecular and functional impairments. Several countermeasures for these negative effects have been proposed, being physical exercise, not only one of the most effective non-pharmacologic strategy but also widely recommended as booster against cancer-related fatigue. It is widely accepted that mitochondria are critical sensors of tissue functionality, both modulated by DOX and exercise. Therefore, this review focuses on the current understanding of the mitochondrial-mediated mechanisms underlying the protective effect of exercise against DOX-induced toxicity, not only limited to the cardiac tissue, but also in other tissues such as skeletal muscle, liver and brain. We here analyze recent developments regarding the beneficial effects of exercise targeting mitochondrial responsive phenotypes against redox changes, mitochondrial bioenergetics, apoptotic, dynamics and quality control signalling affected by DOX treatment.

Untargeted metabolomics analysis of ischemia-reperfusion-injured hearts ex vivo from sedentary and exercise-trained rats

INTRODUCTION

The effects of exercise on the heart and its resistance to disease are well-documented. Recent studies have identified that exercise-induced resistance to arrhythmia is due to the preservation of mitochondrial membrane potential.

OBJECTIVES

To identify novel metabolic changes that occur parallel to these mitochondrial alterations, we performed non-targeted metabolomics analysis on hearts from sedentary and exercise-trained rats challenged with isolated heart ischemia-reperfusion injury (I/R).

METHODS

Eight-week old Sprague-Dawley rats were treadmill trained 5 days/week for 6 weeks (exercise duration and intensity progressively increased to 1 h at 30 m/min up a 10.5% incline, 75-80% VO_2max). The recovery of pre-ischemic function for sedentary rat hearts was 28.8 ± 5.4% (N = 12) compared to exercise trained hearts, which recovered 51.9% ± 5.7 (N = 14) (p < 0.001).

RESULTS

Non-targeted GC-MS metabolomics analysis of (1) sedentary rat hearts; (2) exercise-trained rat hearts; (3) sedentary rat hearts challenged with global ischemia-reperfusion (I/R) injury; and (4) exercise-trained rat hearts challenged with global I/R (10/group) revealed 15 statistically significant metabolites between groups by ANOVA using Metaboanalyst (p < 0.001). Enrichment analysis of these metabolites for pathway-associated metabolic sets indicated a > 10-fold enrichment for ammonia recycling and protein biosynthesis. Subsequent comparison of the sedentary hearts post-I/R and exercise-trained hearts post-I/R further identified significant differences in three metabolites (oleic acid, pantothenic acid, and campesterol) related to pantothenate and CoA biosynthesis (p ≤ 1.24E-05, FDR ≤ 5.07E-4).

CONCLUSIONS

These studies shed light on novel mechanisms in which exercise-induced cardioprotection occurs in I/R that complement both the mitochondrial stabilization and antioxidant mechanisms recently described. These findings also link protein synthesis and protein degradation (protein quality control mechanisms) with exercise-linked cardioprotection and mitochondrial susceptibility for the first time in cardiac I/R.

Hepatopulmonary Syndrome: Oxidative Stress and Physical Exercise

Hepatopulmonary syndrome (HPS) may be defined by hepatic disease, gas exchange abnormalities that may lead to hypoxaemia, and the presence of pulmonary vascular dilations. The balance between the many substances involved in vasodilation and vasoconstriction is regulated by the liver; thus, liver damage may generate systemic changes throughout the body. The pulmonary tissue may be damaged by reactive oxygen species or nitric oxide. Dyspnoea is the most frequent pulmonary symptom, caused by tissue damage, and may become worse when an individual exercises. In experimental research the surgical model of bile duct ligation is the optimal model to simulate the typical lung alterations present in HPS, which results in an increase in oxidative stress in hepatic and pulmonary tissues. In liver injury, the muscular system may also be damaged, for example sarcopenia may seriously aggravate cirrhosis and is associated with cirrhotic patient mortality. Muscular changes can be explained by the actions of myostatin and insulin-like growth factor and the increase in body levels of ammonia. As a result of impaired cardiopulmonary and muscular conditions, HPS patients may exhibit a low exercise tolerance, low muscle strength, and low functionality. Liver disease can contribute to HPS oxidative stress and is one of the main factors responsible for the reduction of gas exchange. Physical exercise can be performed as a way of modifying this pathophysiological state. Studies that have investigated physical exercise as a therapy for cirrhosis suggest that this approach may be beneficial for cirrhotic patients, primarily with regard to muscular and cardiorespiratory injuries.

Melatonin Supplementation Ameliorates Energy Charge and Oxidative Stress Induced by Acute Exercise in Rat Heart Tissue

BACKGROUND

Regular physical exercises may help people to be more resistant to everyday problems; however, how acute and intense exercises affect the heart tissues functioning with maximum capacity and how melatonin changes the effect of acute and intense exercises are still not obvious. We aimed to comprehend whether melatonin intravenous injection supports the oxidative/antioxidative conditions and energy charge in heart tissues of rats exposed to acute swimming exercise.

METHODS

Thirty Wistar-albino male rats were categorized into 3 groups with equal number of subjects. Control group performed no application, and acute intensive swimming exercise group were subjected to acute intensive swimming exercise for 30 minutes, and melatonin group were applied 25 mg/kg single dose melatonin administration prior to 30 minutes acute intensive swimming exercise. The levels of malondialdehyde (MDA), and superoxide dismutase, catalase and glutathione peroxidase activities were measured by spectrophotometric method; and the levels of 3-nitrotyrosine (3-NT) and energy charge were determined by a high performance liquid chromatography.

RESULTS

Tissue MDA and 3-NT levels of the acute intensive exercise group were found to be higher than the control group. It was also found that the melatonin administration increased the energy charge and antioxidant activities, while decreased tissue MDA and 3-NT levels in heart tissues. Our results provide evidence for melatonin that can exert potent protective effects on oxidative stress and energy charge for heart tissues in acute swimming exercise.

CONCLUSIONS

These findings suggest that the direct beneficial effects of melatonin could be potentially applied on prevention of oxidative stress and energy deficit.

Potential signaling pathways of acute endurance exercise-induced cardiac autophagy and mitophagy and its possible role in cardioprotection

Cardiac myocytes are terminally differentiated cells and possess extremely limited regenerative capacity; therefore, preservation of mature cardiac myocytes throughout the individual's entire life span contributes substantially to healthy living. Autophagy, a lysosome-dependent cellular catabolic process, is essential for normal cardiac function and mitochondria maintenance. Therefore, it may be reasonable to hypothesize that if endurance exercise promotes cardiac autophagy and mitochondrial autophagy or mitophagy, exercise-induced cardiac autophagy (EICA) or exercise-induced cardiac mitophagy (EICM) may confer propitious cellular environment and thus protect the heart against detrimental stresses, such as an ischemia-reperfusion (I/R) injury. However, although the body of evidence supporting EICA and EICM is growing, the molecular mechanisms of EICA and EICM and their possible roles in cardioprotection against an I/R injury are poorly understood. Here, we introduce the general mechanisms of autophagy in an attempt to integrate potential molecular pathways of EICA and EICM and also highlight a potential insight into EICA and EICM in cardioprotection against an I/R insult.

Physical Activity, Obesity, and Subclinical Myocardial Damage

OBJECTIVES

This study sought to evaluate the association of physical activity with chronic myocardial damage, assessed by elevated high-sensitivity cardiac troponin T (hs-cTnT), in individuals with and without obesity.

BACKGROUND

Physical activity is associated with reduced risk of heart failure (HF), particularly among obese people. The role of chronic myocardial damage in this association is uncertain.

METHODS

We studied 9,427 participants in the Atherosclerosis Risk in Communities Study without cardiovascular disease, with body mass index >18.5 kg/m2. Physical activity was categorized per American Heart Association guidelines as recommended, intermediate, or poor. We evaluated cross-sectional associations of physical activity and obesity with elevated hs-cTnT (≥14 ng/l). In prospective analyses, we quantified the association of elevated hs-cTnT with HF risk within cross-categories of baseline physical activity and obesity.

RESULTS

People with poor physical activity were more likely to have elevated hs-cTnT than those with recommended levels (odds ratio [OR]: 1.39; 95% confidence interval [CI]: 1.15 to 1.68). In cross-categories of physical activity and obesity, using the non-obese/recommended activity group as the reference, individuals with obesity and poor activity were most likely to have elevated hs-cTnT (OR: 2.46; 95% CI: 1.91 to 3.19), whereas the obese/recommended activity group had a weaker association (OR: 1.68; 95% CI: 1.28 to 2.21; p < 0.001 for interaction between physical activity and obesity). In prospective analyses, elevated hs-cTnT was strongly associated (p < 0.001) with incident HF in all obesity/physical activity cross-categories (p > 0.20 for interaction).

CONCLUSIONS

Physical activity is inversely associated with chronic subclinical myocardial damage. Physical activity might lessen the association between obesity and subclinical myocardial damage, which could represent a mechanism by which physical activity reduces HF risk.

Mitochondrial Metabolism in Aging Heart

Altered mitochondrial metabolism is the underlying basis for the increased sensitivity in the aged heart to stress. The aged heart exhibits impaired metabolic flexibility, with a decreased capacity to oxidize fatty acids and enhanced dependence on glucose metabolism. Aging impairs mitochondrial oxidative phosphorylation, with a greater role played by the mitochondria located between the myofibrils, the interfibrillar mitochondria. With aging, there is a decrease in activity of complexes III and IV, which account for the decrease in respiration. Furthermore, aging decreases mitochondrial content among the myofibrils. The end result is that in the interfibrillar area, there is ≈50% decrease in mitochondrial function, affecting all substrates. The defective mitochondria persist in the aged heart, leading to enhanced oxidant production and oxidative injury and the activation of oxidant signaling for cell death. Aging defects in mitochondria represent new therapeutic targets, whether by manipulation of the mitochondrial proteome, modulation of electron transport, activation of biogenesis or mitophagy, or the regulation of mitochondrial fission and fusion. These mechanisms provide new ways to attenuate cardiac disease in elders by preemptive treatment of age-related defects, in contrast to the treatment of disease-induced dysfunction.

Levels of Hepatic Activating Transcription Factor 6 and Caspase-3 Are Downregulated in Mice after Excessive Training

Recently, we demonstrated that different running overtraining (OT) protocols with the same external load, but performed downhill (OTR/down), uphill (OTR/up), and without inclination (OTR), led to hepatic fat accumulation. As the disruption of endoplasmic reticulum (ER) homeostasis is linked to animal models of fatty liver disease, we investigated the effects of these OT models on the proteins related to ER stress (i.e., BiP, inositol-requiring enzyme 1, protein kinase RNA-like endoplasmic reticulum kinase, eIF2alpha, ATF6beta, and glucose-regulated protein 94) and apoptosis (C/EBP-homologous protein, Caspase-3, 4, and 12, Bax, and tumor necrosis factor receptor-associated factor 2) in livers of C57BL/6 mice. Also, aerobic training can attenuate cardiac ER stress and improve exercise capacity. Therefore, we investigated whether the decrease in performance induced by our OT protocols is linked to ER stress and apoptosis in mouse hearts. The rodents were divided into six groups: naïve (N, sedentary mice), control (CT, sedentary mice submitted to the performance evaluations), trained (TR), OTR/down, OTR/up, and OTR groups. Rotarod, incremental load, exhaustive, and grip force tests were used to evaluate performance. After the grip force test, the livers and cardiac muscles (i.e., left ventricle) were removed and used for immunoblotting. All of the OT protocols led to similar responses in the performance parameters and displayed significantly lower hepatic ATF6beta values compared to the N group. The OTR/down group exhibited lower liver cleaved caspase-3 values compared to the CT group. However, the other proteins related to ER stress and apoptosis were not modulated. Also, the cardiac proteins related to ER stress and apoptosis were not modulated in the experimental groups. In conclusion, the OT protocols decreased the levels of hepatic ATF6beta, and the OTR/down group decreased the levels of hepatic cleaved caspase-3. Also, the decrease in performance induced by our OT models is not associated with ER stress and apoptosis in mice hearts.

Aerobic exercise in anthracycline-induced cardiotoxicity: a systematic review of current evidence and future directions

Cancer and cardiovascular disease are major causes of morbidity and mortality worldwide. Older cancer patients often wrestle with underlying heart disease during cancer therapy, whereas childhood cancer survivors are living long enough to face long-term unintended cardiac consequences of cancer therapies, including anthracyclines. Although effective and widely used, particularly in the pediatric population, anthracycline-related side effects including dose-dependent association with cardiac dysfunction limit their usage. Currently, there is only one United States Food and Drug Administration-approved drug, dexrazoxane, available for the prevention and mitigation of cardiotoxicity related to anthracycline therapy. While aerobic exercise has been shown to reduce cardiovascular complications in multiple diseases, its role as a therapeutic approach to mitigate cardiovascular consequences of cancer therapy is in its infancy. This systematic review aims to summarize how aerobic exercise can help to alleviate unintended cardiotoxic side effects and identify gaps in need of further research. While published work supports the benefits of aerobic exercise, additional clinical investigations are warranted to determine the effects of different exercise modalities, timing, and duration to identify optimal aerobic training regimens for reducing cardiovascular complications, particularly late cardiac effects, in cancer survivors exposed to anthracyclines.

Regular treadmill exercise inhibits mitochondrial accumulation of cholesterol and oxysterols during myocardial ischemia-reperfusion in wild-type and ob/ob mice

Mitochondria play a central role in the irreversible damages induced to the heart by a prolonged period of ischemia followed by reperfusion. We previously demonstrated that (1) myocardial ischemia-reperfusion induces mitochondrial accumulation of cholesterol and oxysterols that are deleterious for the organelle; (2) inhibition of cholesterol and oxysterol accumulation prevents mitochondrial injury at reperfusion; (3) exercise is cardioprotective and remains efficient in the presence of co-morbidities such as obesity. The aim of this study was to investigate whether regular exercise limits mitochondrial cholesterol and oxysterol accumulation in wild-type and obese mice. Wild-type C57BL/6J and obese (ob/ob) mice were assigned to sedentary conditions or regular treadmill exercise and submitted to 30min of coronary artery occlusion followed by 15min of reperfusion. Regular exercise improved oxidative phosphorylation, restored the antioxidant capacity of the heart by increasing the expression of SOD1 and catalase and reduced the mitochondrial generation of oxysterols in wild-type as well as in ob/ob mice. In wild-type animals, exercise limited the production of oxysterols. In ob/ob mice, despite hypercholesterolemia, chronic exercise abolished the mitochondrial accumulation of cholesterol and concomitantly reduced the generation of 7α-hydroxycholesterol, 7-ketocholesterol and cholesterol-5α,6α-epoxide. In conclusion, regular exercise prevents the mitochondrial accumulation of cholesterol and oxysterols which occurs during early reperfusion of an ischemic myocardium in mice. This effect is observed in normo and hypercholesterolemic animals. It may be partly responsible for the antioxidant properties of regular exercise and contribute to its cardioprotective effect in obese conditions.

Oxidative status of the myocardium in response to different intensities of physical training

The intensity of exercise determines the metabolic pathway and the energetic substrate that is spent. Our study sought to identify the effects of different intensities of swimming on myocardial oxidative status and the blood lipid profile. Eighty Wistar rats (male and female) submitted to different intensities of a swimming regimen (low, LS; moderate, MS; or high, HS) for 16 weeks. Samples of blood and myocardium from the left ventricle were collected to determine lipid profiles and oxidative status. Reactive oxygen species (ROS) and antioxidant capacity against peroxyl radicals (ACAP), lipid profiles and lipid peroxidation was analyzed. ROS levels and ACAP were higher in male rats than in female rats overall (p<0.05). However, ACAP in the myocardium was significantly elevated in LS female rats compared to the MS and HS female rats, which had a significantly lower ACAP compared to all other groups. LS and MS training in both sexes and HS training (in females) led to significant decreases in the heart's lipid peroxidation. Amelioration of the lipid profile and reduction in oxidative damage contributed to a physiological state that benefits cardiovascular function in exercised animals. The results show that low and moderate intensity exercise promotes beneficial adaptations.

Mitochondrial dysfunction in bipolar disorder: Evidence, pathophysiology and translational implications

Bipolar disorder (BD) is a chronic psychiatric illness characterized by severe and biphasic changes in mood. Several pathophysiological mechanisms have been hypothesized to underpin the neurobiology of BD, including the presence of mitochondrial dysfunction. A confluence of evidence points to an underlying dysfunction of mitochondria, including decreases in mitochondrial respiration, high-energy phosphates and pH; changes in mitochondrial morphology; increases in mitochondrial DNA polymorphisms; and downregulation of nuclear mRNA molecules and proteins involved in mitochondrial respiration. Mitochondria play a pivotal role in neuronal cell survival or death as regulators of both energy metabolism and cell survival and death pathways. Thus, in this review, we discuss the genetic and physiological components of mitochondria and the evidence for mitochondrial abnormalities in BD. The final part of this review discusses mitochondria as a potential target of therapeutic interventions in BD.

Exercise-induced protection against reperfusion arrhythmia involves stabilization of mitochondrial energetics

Mitochondria influence cardiac electrophysiology through energy- and redox-sensitive ion channels in the sarcolemma, with the collapse of energetics believed to be centrally involved in arrhythmogenesis. This study was conducted to determine if preservation of mitochondrial membrane potential (ΔΨm) contributes to the antiarrhythmic effect of exercise. We utilized perfused hearts, isolated myocytes, and isolated mitochondria exposed to metabolic challenge to determine the effects of exercise on cardiac mitochondria. Hearts from sedentary (Sed) and exercised (Ex; 10 days of treadmill running) Sprague-Dawley rats were perfused on a two-photon microscope stage for simultaneous measurement of ΔΨm and ECG. After ischemia-reperfusion, the collapse of ΔΨm was commensurate with the onset of arrhythmia. Exercise preserved ΔΨm and decreased the incidence of fibrillation/tachycardia (P < 0.05). Our findings in intact hearts were corroborated in isolated myocytes exposed to in vitro hypoxia-reoxygenation, with Ex rats demonstrating enhanced redox control and sustained ΔΨm during reoxygenation. Finally, we induced anoxia-reoxygenation in isolated mitochondria using high-resolution respirometry with simultaneous measurement of respiration and H2O2 Mitochondria from Ex rats sustained respiration with lower rates of H2O2 emission than Sed rats. Exercise helps sustain postischemic mitochondrial bioenergetics and redox homeostasis, which is associated with preserved ΔΨm and protection against reperfusion arrhythmia. The reduction of fatal ventricular arrhythmias through exercise-induced mitochondrial adaptations indicates that mitochondrial therapeutics may be an effective target for the treatment of heart disease.

Endurance training prevents negative effects of the hypoxia mimetic dimethyloxalylglycine on cardiac and skeletal muscle function

Hypoxic preconditioning is a promising strategy to prevent hypoxia-induced damages to several tissues. This effect is related to prior stabilization of the hypoxia-inducible factor-1α via inhibition of the prolyl-hydroxylases (PHDs), which are responsible for its degradation under normoxia. Although PHD inhibition has been shown to increase endurance performance in rodents, potential side effects of such a therapy have not been explored. Here, we investigated the effects of 1 wk of dimethyloxalylglycine (DMOG) treatment (150 mg/kg) on exercise capacity, as well as on cardiac and skeletal muscle function in sedentary and endurance-trained rats. DMOG improved maximal aerobic velocity and endurance in both sedentary and trained rats. This effect was associated with an increase in red blood cells without significant alteration of skeletal muscle contractile properties. In sedentary rats, DMOG treatment resulted in enhanced left ventricle (LV) weight together with impairment in diastolic function, LV relaxation, and pulse pressure. Moreover, DMOG decreased maximal oxygen uptake (state 3) of isolated mitochondria from skeletal muscle. Importantly, endurance training reversed the negative effects of DMOG treatment on cardiac function and restored maximal mitochondrial oxygen uptake to the level of sedentary placebo-treated rats. In conclusion, we provide here evidence that the PHD inhibitor DMOG has detrimental influence on myocardial and mitochondrial function in healthy rats. However, one may suppose that the deleterious influence of PHD inhibition would be potentiated in patients with already poor physical condition. Therefore, the present results prompt us to take into consideration the potential side effects of PHD inhibitors when administrated to patients.

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.

Molecular Characterization of Reactive Oxygen Species in Myocardial Ischemia-Reperfusion Injury

Myocardial ischemia-reperfusion (I/R) injury is experienced by individuals suffering from cardiovascular diseases such as coronary heart diseases and subsequently undergoing reperfusion treatments in order to manage the conditions. The occlusion of blood flow to the tissue, termed ischemia, can be especially detrimental to the heart due to its high energy demand. Several cellular alterations have been observed upon the onset of ischemia. The danger created by cardiac ischemia is somewhat paradoxical in that a return of blood to the tissue can result in further damage. Reactive oxygen species (ROS) have been studied intensively to reveal their role in myocardial I/R injury. Under normal conditions, ROS function as a mediator in many cell signaling pathways. However, stressful environments significantly induce the generation of ROS which causes the level to exceed body's antioxidant defense system. Such altered redox homeostasis is implicated in myocardial I/R injury. Despite the detrimental effects from ROS, low levels of ROS have been shown to exert a protective effect in the ischemic preconditioning. In this review, we will summarize the detrimental role of ROS in myocardial I/R injury, the protective mechanism induced by ROS, and potential treatments for ROS-related myocardial injury.

Modulation of cardiovascular toxicity in Hodgkin lymphoma: potential role and mechanisms of aerobic training

Hodgkin lymphoma (HL) outcomes have improved due to advances in cancer treatment. However, HL survivors remain at increased risk for cardiovascular (CV) morbidity and mortality related to the long-term cardiotoxicity of HL treatment, particularly anthracycline chemotherapy and mediastinal radiotherapy. The role of aerobic training for the prevention of CV disease in the general population has been well established. However the safety and efficacy of aerobic training on CV outcomes has not been well studied in HL survivors. The purpose of this paper is to provide an up-to-date summary of the treatment-related adverse CV effects in HL survivors, review the CV benefits of exercise and review the limited evidence on the potential CV benefit of aerobic training in HL survivors.

Exercise Prevention of Cardiovascular Disease in Breast Cancer Survivors

Thanks to increasingly effective treatment, breast cancer mortality rates have significantly declined over the past few decades. Following the increase in life expectancy of women diagnosed with breast cancer, it has been recognized that these women are at an elevated risk for cardiovascular disease due in part to the cardiotoxic side effects of treatment. This paper reviews evidence for the role of exercise in prevention of cardiovascular toxicity associated with chemotherapy used in breast cancer, and in modifying cardiovascular risk factors in breast cancer survivors. There is growing evidence indicating that the primary mechanism for this protective effect appears to be improved antioxidant capacity in the heart and vasculature and subsequent reduction of treatment-related oxidative stress in these structures. Further clinical research is needed to determine whether exercise is a feasible and effective nonpharmacological treatment to reduce cardiovascular morbidity and mortality in breast cancer survivors, to identify the cancer therapies for which it is effective, and to determine the optimal exercise dose. Safe and noninvasive measures that are sensitive to changes in cardiovascular function are required to answer these questions in patient populations. Cardiac strain, endothelial function, and cardiac biomarkers are suggested outcome measures for clinical research in this field.

Genetic manipulation of cardiac ageing

Ageing in humans is associated with a significant increase in the prevalence of cardiovascular disease. We still do not fully understand the molecular mechanisms underpinning this correlation. However, a number of insights into which genes control cardiac ageing have come from studying hearts of the fruit fly, Drosophila melanogaster. The fly's simple heart tube has similar molecular structure and basic physiology to the human heart. Also, both fly and human hearts experience significant age-related morphological and functional decline. Studies on the fly heart have highlighted the involvement of key nutrient sensing, ion channel and sarcomeric genes in cardiac ageing. Many of these genes have also been implicated in ageing of the mammalian heart. Genes that increase oxidative stress, or are linked to cardiac hypertrophy or neurodegenerative diseases in mammals also affect cardiac ageing in the fruit fly. Moreover, fly studies have demonstrated the potential of exercise and statins to treat age-related cardiac disease. These results show the value of Drosophila as a model to discover the genetic causes of human cardiac ageing.

Endoplasmic Reticulum Stress Response in Non-alcoholic Steatohepatitis: The Possible Role of Physical Exercise

Sedentary lifestyle coupled with excessive consumption of high caloric food has been related to the epidemic increase of non-alcoholic fatty liver disease, which can progress from simple steatosis to non-alcoholic steatohepatitis (NASH), fibrosis, cirrhosis and, eventually, may culminate in hepatocellular carcinoma. Although the precise mechanisms underlying the progression of NASH are not completely understood, endoplasmic reticulum (ER) dysfunction seems to play a key role in the process. Hepatic ER stress has been associated to hepatic steatosis, insulin resistance, inflammation, oxidative stress and hepatocyte death, contributing to liver dysfunction. Physical exercise seems to be the most effective preventive and therapeutic non-pharmacological strategy to mitigate several features related to NASH, possibly targeting most of the referred mechanisms associated with the pathophysiology of ER-related NASH. Nevertheless, little is known about the impact of physical exercise on NASH-related ER stress. In this review, we will discuss the ER stress associated to NASH conditions and highlight the possible benefits of physical exercise in the attenuation and/or reversion of NASH-related ER stress.

Mechanisms Involved in Exercise-Induced Cardioprotection: A Systematic Review

BACKGROUND

Acute myocardial infarction is the leading cause of morbidity and mortality worldwide. Furthermore, research has shown that exercise, in addition to reducing cardiovascular risk factors, can also protect the heart against injury due to ischemia and reperfusion through a direct effect on the myocardium. However, the specific mechanism involved in exerciseinduced cardiac preconditioning is still under debate.

OBJECTIVE

To perform a systematic review of the studies that have addressed the mechanisms by which aerobic exercise promotes direct cardioprotection against ischemia and reperfusion injury.

METHODS

A search was conducted using MEDLINE, Literatura Latino-Americana e do Caribe de Informação em Ciências da Saúde, and Scientific Electronic Library Online databases. Data were extracted in a standardized manner by two independent researchers, who were responsible for assessing the methodological quality of the studies.

RESULTS

The search retrieved 78 studies; after evaluating the abstracts, 30 studies were excluded. The manuscripts of the remaining 48 studies were completely read and, of these, 20 were excluded. Finally, 28 studies were included in this systematic review.

CONCLUSION

On the basis of the selected studies, the following are potentially involved in the cardioprotective response to exercise: increased heat shock protein production, nitric oxide pathway involvement, increased cardiac antioxidant capacity, improvement in ATP-dependent potassium channel function, and opioid system activation. Despite all the previous investigations, further research is still necessary to obtain more consistent conclusions.

How exercise may amend metabolic disturbances in diabetic cardiomyopathy

SIGNIFICANCE

Over-nutrition and sedentary lifestyle has led to a worldwide increase in obesity, insulin resistance, and type 2 diabetes (T2D) associated with an increased risk of development of cardiovascular disorders. Diabetic cardiomyopathy, independent of hypertension or coronary disease, is induced by a range of systemic changes and may through multiple processes result in functional and structural cardiac derangements. The pathogenesis of this cardiomyopathy is complex and multifactorial, and it will eventually lead to reduced cardiac working capacity and increased susceptibility to ischemic injury.

RECENT ADVANCES

Metabolic disturbances such as altered lipid handling and substrate utilization, decreased mechanical efficiency, mitochondrial dysfunction, disturbances in nonoxidative glucose pathways, and increased oxidative stress are hallmarks of diabetic cardiomyopathy. Interestingly, several of these disturbances are found to precede the development of cardiac dysfunction.

CRITICAL ISSUES

Exercise training is effective in the prevention and treatment of obesity and T2D. In addition to its beneficial influence on diabetes/obesity-related systemic changes, it may also amend many of the metabolic disturbances characterizing the diabetic myocardium. These changes are due to both indirect effects, exercise-mediated systemic changes, and direct effects originating from the high contractile activity of the heart during physical training.

FUTURE DIRECTIONS

Revealing the molecular mechanisms behind the beneficial effects of exercise training is of considerable scientific value to generate evidence-based therapy and in the development of new treatment strategies.

Endurance training prevents TWEAK but not myostatin-mediated cardiac remodelling in cancer cachexia

Strategies to prevent tumour burden-induced cardiac remodelling that might progress to heart failure are necessary to improve patients' health outcomes and tolerability to cancer therapies. Exercise has been suggested as a measure to prevent cardiac damage; however, its effectiveness on regulating cardiac remodelling secondary to cancer was never addressed. Using an animal model of mammary tumorigenesis, we studied the impact of 35weeks of endurance training on heart, focusing on the signalling pathways modulated by pro-inflammatory and wasting cytokines. The cardiac fibrosis and myofiber disorganization induced by tumour burden was paralleled by the increase of myostatin and TWEAK with the activation of signalling pathways involving Smad-3, NF-κB, TRAF-6 and atrogin-1. The activation of Akt/mTOR was observed in heart from rats with tumours, for which contributed the extracellular matrix. Endurance training prevented the increase of serum and cardiac TWEAK promoted by cancer, as well as the activation of NF-κB, TRAF6, atrogin-1 and p70S6K in heart. Data highlight the impact of exercise in the modulation of signalling pathways activated by wasting cytokines and the resulting outcomes on heart adaptation. Future studies focused on the cellular pathways underlying cardiac remodelling will assist in the development of exercise programs targeting cancer-related cardiac alterations.

Physical exercise prior and during treatment reduces sub-chronic doxorubicin-induced mitochondrial toxicity and oxidative stress

Doxorubicin (DOX) is an anti-cancer agent whose clinical usage results in a cumulative and dose-dependent cardiotoxicity. We have previously shown that exercise performed prior to DOX treatment reduces the resulting cardiac(mito) toxicity. We sought to determine the effects on cardiac mitochondrial toxicity of two distinct chronic exercise models (endurance treadmill training-TM and voluntary free-wheel activity-FW) when used prior and during DOX treatment. Male-young Sprague-Dawley rats were divided into six groups (n=6 per group): SAL+SED (saline sedentary), SAL+TM (12-weeks TM), SAL+FW (12-weeks FW), DOX+SED (7-weeks of chronic DOX treatment 2mg/kg per week), DOX+TM and DOX+FW. DOX administration started 5weeks after the beginning of the exercise protocol. Heart mitochondrial ultrastructural alterations, mitochondrial function (oxygen consumption and membrane potential), semi-quantification of oxidative phosphorylation (OXPHOS) proteins and their in-gel activity, as well as proteins involved in mitochondrial oxidative stress (SIRT3, p66shc and UCP2), biogenesis (PGC1α and TFAM), acetylation and markers for oxidative damage (carbonyl groups, MDA,SH, aconitase, Mn-SOD activity) were evaluated. DOX treatment resulted in ultrastructural and functional alterations and decreased OXPHOS. Moreover, DOX decreased complex I activity and content, mitochondrial biogenesis (TFAM), increased acetylation and oxidative stress. TM and FW prevented DOX-induced alteration in OXPHOS, the increase in oxidative stress, the decrease in complex V activity and in complex I activity and content. DOX-induced decreases in TFAM and SIRT3 content were prevented by TM only. Both chronic models of physical exercise performed before and during the course of sub-chronic DOX treatment translated into an improved mitochondrial bioenergetic fitness, which may result in part from the prevention of mitochondrial oxidative stress and damage.

Effect of exercise training on oxidative stress and mitochondrial function in rat heart and gastrocnemius muscle

OBJECTIVE

This study aimed to explore the effect of endurance training on oxidative parameters and mitochondrial function in gastrocnemius and heart muscle.

METHODS

Male Wistar rats were trained by running for 6 weeks. In vitro measurements of the rates of hydroxyl radical ((•)OH) production, oxygen consumption (in either the absence, basal rate (V0), or the presence, maximal rate (Vmax), of adenosine diphosphate), and adenosine triphosphate (ATP) production were made simultaneously in permeabilized fibers. The mitochondrial function was explored after exposure or non-exposure to an in vitro generator system of reactive oxygen species (ROS).

RESULTS

Vmax was not affected by training, but V0 decreased. In conditions of maximal mitochondrial functioning, an increase in ATP rate and a decrease in (•)OH production occurred simultaneously. In vitro ROS exposure disturbed mitochondrial function, but training modified the vulnerability of Vmax and ATP rate to ROS in different ways.

DISCUSSION

We hypothesize that the part of Vmax devoted to proton leakage was decreased in trained rats, consequently improving ATP synthesis. The data suggest that, after training, there is more efficient use of electrons in respiratory chain energy production, rather than a greater ROS scavenging capacity.