Responses of rat myocardial antioxidant defences and heat shock protein HSP72 induced by 12 and 24-week treadmill training

Effect of Stanozolol and/or Cannabis Abuse on Hypertrophic Mechanism and Oxidative Stress of Male Albino Rat Cardiac Tissue in Relation to Exercise: A Sport Abuse Practice

Adolescents commonly co-abuse many drugs including anabolic androgenic steroids either they are athletes or non-athletes. Stanozolol is the major anabolic used in recent years and was reported grouped with cannabis. The current study aimed at evaluating the biochemical and histopathological changes related to the hypertrophic effects of stanozolol and/or cannabis whether in condition of exercise practice or sedentary conditions. Adult male Wistar albino rats received either stanozolol (5 mg/kg, s.c), cannabis (10 mg/kg, i.p.), and a combination of both once daily for two months. Swimming exercise protocol was applied as a training model. Relative heart weight, oxidative stress biomarkers, cardiac tissue fibrotic markers were evaluated. Left ventricular morphometric analysis and collagen quantification was done. The combined treatment exhibited serious detrimental effects on the heart tissues. It increased heart tissue fibrotic markers (Masson's trichrome stain (p < 0.001), cardiac COL3 (p < 0.0001), and VEGF-A (p < 0.05)), lowered heart glutathione levels (p < 0.05) and dramatically elevated oxidative stress (increased malondialdehyde (p < 0.0001) and 8-OHDG (p < 0.0001)). Training was not ameliorating for the observed effects. Misuse of cannabis and stanozolol resulted in more hypertrophic consequences of the heart than either drug alone, which were at least largely assigned to oxidative stress, heart tissue fibrotic indicators, histological alterations, and morphometric changes.

Can Active Aerobic Exercise Reduce the Risk of Cardiovascular Disease in Prehypertensive Elderly Women by Improving HDL Cholesterol and Inflammatory Markers?

This study aims to verify the efficacy of exercise programs designed to prevent and treat hypertension-induced cardiovascular disease (CVD) by analyzing the effects of a 6-month active aerobic exercise program, administered to prehypertensive elderly women, on reducing the risk of developing CVD by enhancing their physical fitness level and improving the detailed markers of high-density lipoprotein cholesterol (HDL-C) and inflammatory markers. We assigned the elderly women (≥65 years) recruited into normal blood pressure (120–129/80–84; NBP, n = 18) and high-normal blood pressure (130–139/85–89; HNBP, n = 12) groups according to the European guidelines for the management of arterial hypertension. The exercise program was made up of combined workouts of elastic band resistance exercise and aerobics with dance music. The program took place three times a week for six months, with each session lasting 60 min. We measured pre- and post-intervention body composition, blood pressure, physical fitness level, blood lipids profile, HDL-C, SAA, TNF-α, IL-6, IL-4, IL-15, CRP, and HSP70 and calculated the Framingham risk scores for comparison. A significant post-intervention reduction in the mean systolic blood pressure (SBP) was observed in the HNBP group (p < 0.001), with significant increase in HDL-C (p < 0.01) and significant decrease in serum amyloid A (SAA) concentration (p < 0.01). A significant improvement in physical fitness factors such as physical efficiency index (PEI) was also observed in the HNBP group (p < 0.05). The post-intervention TNF-α, IL-6, and SAA concentrations were more significantly lower in the HNBP than in the NBP group (p < 0.05). Compared to the baseline values, a significant decrease in SAA concentration (p < 0.01) and significant increase in HSP70 concentration (p < 0.001) were observed in the HNBP group. The HNBP group’s 10-year CVD risk was also significantly reduced (p < 0.05). The pre–post differences in SBP and DBP were significantly correlated with those in the anti-inflammatory markers IL-4 and IL-15 (p < 0.01). In conclusion, the 6-month active aerobic exercise program of moderate intensity administered to prehypertensive elderly women (≥65 years) had the effect of reducing the 10-year CVD risk through a substantial reduction in SBP, overall physical fitness improvement, increase in HDL-C, decrease in SAA concentration, and substantial decrease in inflammatory biomarkers. It was also confirmed that an increase in anti-inflammatory markers, which showed a small range of increase with respect to the decrease in blood pressure, may have a major effect.

Pharmacological and Therapeutic Aspects of Plants from the Genus Ferula: A Comprehensive Review

Inspired by nature, humankind has been able to attain significant achievements in the drug and food industries. Particularly, medicinal plants are a rich source of medicinal, cosmetic, sanitary, and aromatic substances. Genus Ferula from the Apiaceae family is a plant genus that possesses over 170 species, which have been carefully documented with regard to their medicinal properties. Ferula spp. affects many body organs, and their respective functions, in humans, such as the immune system, gastrointestinal tract, genitourinary, endocrine, respiratory, cardiovascular, nervous system, bone (skeleton), and teeth. In spite of the benefits, ferulosis (Ferula toxicity) is an important aspect of Ferula consumption in humans and animals. Hemorrhagic problems and infertility are important signs of ferulosis. In this review, we have described all of the effects of the active ingredients of Ferula spp. and their mechanisms of actions, when known, based on an extensive literature review. Thus, our review opens a window of the benefits of Ferula as a phyto-pharmaceutical and its therapeutic applications in pharmacy, dentistry, and medicine.

Combination of exercise training and L-arginine reverses aging process through suppression of oxidative stress, inflammation, and apoptosis in the rat heart

Aging-induced progressive decline of molecular and metabolic factors in the myocardium is suggested to be related with heart dysfunction and cardiovascular disease. Therefore, we evaluated the effects of exercise training and L-arginine supplementation on oxidative stress, inflammation, and apoptosis in ventricle of the aging rat heart. Twenty-four 24-month-aged Wistar rats were randomly divided into four groups: the aged control, aged exercise, aged L-arginine (orally administered with 150 mg/kg for 12 weeks), and aged exercise + L-arginine groups. Six 4-month-old rats were also considered the young control. Animals with training program performed exercise on a treadmill 5 days/week for 12 weeks. After 12 weeks, protein levels of Bax, Bcl-2, pro-caspase-3/cleaved caspase-3, cytochrome C, and heat shock protein (HSP)-70 were assessed. Tissue contents of total anti-oxidant capacity, superoxide dismutase, catalase, and levels of tumor necrosis factor alpha (TNF-α), interleukin (IL)-1β, and IL-6 were analyzed. Histological and fibrotic changes were also evaluated. Treadmill exercise and L-arginine supplementation significantly alleviated aging-induced apoptosis with enhancing HSP-70 expression, increasing anti-oxidant enzyme activity, and suppressing inflammatory markers in the cardiac myocytes. Potent attenuation in apoptosis, inflammation, and oxidative stress was indicated in the rats with the combination of L-arginine supplementation and exercise program in comparison with each group (p < 0.05). In addition, fibrosis percentage and collagen accumulation were significantly lower in the rats with the combination treatment of L-arginine and exercise (p < 0.05). Treadmill exercise and L-arginine supplementation provided protection against age-induced increase in the myocyte loss and formation of fibrosis in the ventricle through potent suppression of oxidative stress, inflammations, and apoptosis pathways.

Detectable levels of eHSP72 in plasma are associated with physical activity and antioxidant enzyme activity levels in hypertensive subjects

Previous studies reported that extracellular HSP72 (eHSP72) correlates with poor prognosis, markers of vascular dysfunction, and the severity of cardiovascular diseases, associated with a systemic oxidative and inflammatory profile. On the other hand, eHSP72 may represent immune-regulatory signaling that is related to exercise benefits, but the association between physical activity levels and eHSP72 levels is not established. Thus, since regular physical activity may avoid oxidative stress and inflammation, we investigate whether detectable levels of eHSP72 in plasma are associated with physical activity and antioxidant enzyme activity levels in hypertensive subjects. Physical activity levels of hypertensive subjects (n = 140) were measured by tri-axial movement sensor pedometer for 24 h during 5 consecutive days. One day after, blood was collected into heparinized tubes for oxidative stress analyses (catalase-CAT and superoxide dismutase-SOD activities and malondialdehyde levels) or in disodium EDTA tubes for eHSP72 assays. Thus, hypertensive subjects were classified as physically inactive (< 10,000 footsteps/day) or active (> than 10,000 footsteps/day) and according detectable or not detectable eHSP72 levels in plasma, performing the inactive/eHSP72-, active/eHSP72-, inactive/eHSP72+, and active/eHSP72+ groups. We found that detectable levels of eHSP72 in plasma were associated with physical activity levels and low oxidative stress profile (Higher CAT and SOD activities and low malondialdehyde levels). eHSP72 levels can be used as a biomarker of the amount of physical activity necessary to improve antioxidant defense and thus cardiovascular health in hypertensive subjects.

Effects of intermittent ladder-climbing exercise training on mitochondrial biogenesis and endoplasmic reticulum stress of the cardiac muscle in obese middle-aged rats

The aim of this study is to investigate the effects of intermittent ladder-climbing exercise training on mitochondrial biogenesis and ER stress of the cardiac muscle in high fat diet-induced obese middle-aged rats. We induced obesity over 6 weeks of period in 40 male Sprague-Dawley rats around 50 weeks old, and were randomly divided into four experimental groups: chow, HFD, exercise+HFD, and exercise+chow. The exercising groups underwent high-intensity intermittent training using a ladder-climbing and weight exercise 3 days/week for a total of 8 weeks. High-fat diet and concurrent exercise resulted in no significant reduction in body weight but caused a significant reduction in visceral fat weight (p<0.05). Expression of PPARδ increased in the exercise groups and was significantly increased in the high-fat diet+exercise group (p<0.05). Among the ER stress-related proteins, the expression levels of p-PERK and CHOP, related to cardiac muscle damage, were significantly higher in the cardiac muscle of the high-fat diet group (p<0.05), and were significantly reduced by intermittent ladder-climbing exercise training (p<0.05). Specifically, this reduction was greater when the rats underwent exercise after switching back to the chow diet with a reduced caloric intake. Collectively, these results suggest that the combination of intermittent ladder-climbing exercise training and a reduced caloric intake can decrease the levels of ER stress-related proteins that contribute to cardiac muscle damage in obesity and aging. However, additional validation is required to understand the effects of these changes on mitochondrial biogenesis during 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.

Melatonin reduces oxidative stress and cardiovascular changes induced by stanozolol in rats exposed to swimming exercise

OBJECTIVE

Anabolic-androgenic steroids (AAS) are nominated for clinical use to promote protein synthesis in many therapeutic conditions. However, the indiscriminate use of AAS is related to hazardous cardiac disturbances and oxidative stress. We designed a study to investigate whether prolonged treatment with high doses of stanozolol modifies the activities of some antioxidant enzymes in the heart in sedentary and trained rats and whether this treatment causes alterations of cardiovascular parameters. In addition, the effectiveness of melatonin as an antioxidant and as a modulator of the cardiovascular side effects of stanozolol (STA) treatment was analyzed.

MATERIALS AND METHODS

Thirty male Wistar rats were divided into the following six groups: sedentary (S), stanozolol sedentary (SS), stanozolol-melatonin sedentary (SMS), trained (T), stanozolol trained (ST) and stanozolol-melatonin trained (SMT). The stanozolol-treatment rats received 5 mg.kg(-1) by subcutaneous injection before each exercise session (5 d.wk(-1), i.e., 25 mg.kg(-1).wk(-1)), while control groups received only saline solution injection. The melatonin-treatment groups received intraperitoneal injections of melatonin (10 mg.kg(-1)), 5 d.wk(-1) for 6 wk. Electrocardiography, blood pressure and antioxidant enzyme activity measurements were performed at the end of the experimental period for cardiac function and molecular assessment.

RESULTS

This is the first time that the in vivo effects of melatonin treatment on stanozolol-induced cardiovascular side effects have been studied. Stanozolol induced bradycardia and significantly increased cardiac superoxide dismutase and catalase activities. Trained stanozolol-treated rats experienced an increase in blood pressure and relative heart weight, and they developed left cardiac axis deviation. Although melatonin did not prevent cardiac hypertrophy in exercised stanozolol-treated animals, it maintained blood pressure and cardiac catalase activity, and it prevented stanozolol-induced cardiac electrical axis deviation.

CONCLUSION

In conclusion, under our experimental conditions, chronic stanozolol administration induced mild cardiovascular side effects that were partly attenuated by melatonin treatment. However, these results showed that the combination of melatonin and exercise could minimize the stanozolol side effects in the cardiovascular system.

Role of four-week resistance exercise in preserving the heart against ischaemia-reperfusion-induced injury

Objective

We studied the cardioprotective effect of resistance training against ischaemia–reperfusion-induced injury.

Methods

Forty male rats were divided into trained and sedentary groups (n = 20 for each). The trained rats were exercised at 12 repetitions/set, four sets/day and five days/week for four weeks. Transient regional ischaemia of the left anterior descending coronary artery (40 min) was followed by 80 min of reperfusion.

Results

Baseline developed and diastolic pressures and coronary flow were similar in the two groups. While diastolic pressure increased and developed pressure and coronary flow decreased in both the ischaemic and perfusion periods (as indices of cardiac damage), there were no statistically significant differences between the trained and sedentary groups in these parameters. Resistance training did not significantly change the infarct size and apoptosis rate.

Conclusion

We did not see a cardioprotective effect of resistance exercise against ischaemia–reperfusion-induced injury in this study. A precise conclusion about this issue needs more investigations.

Effect of treadmill exercise and Ferula gummosa on myocardial HSP72, vascular function, and antioxidant defenses in spontaneously hypertensive rats

This study evaluates the effect of treadmill exercise and Ferula gummosa (FG) on heat shock protein (HSP72), biomarkers related to vascular function, and oxidant/antioxidant system in the heart tissue of spontaneously hypertensive rats treated with N(ω)-nitro-L-arginine-methyl ester (L-NAME). Fifty adult male Wistar rats are randomly classified into five groups: treadmill exercise, FG, combination of treadmill exercise + FG, L-NAME, and saline. Treadmill exercise was performed between 25 and 64 minutes at the speed of 15-22 m per minute for 8 weeks and five sessions a week. The FG will be fed through gavage with 90 mg/kg dosage. Hypertension was induced by l-NAME (10 mg/kg) for 8 weeks and six sessions a week. Administration of L-NAME for 8 weeks caused significant increase in HSP72, angiotensin-converting enzyme (ACE), and protein carbonyl (PC), and significant decrease in glutathione peroxidase (GPx) and nitric oxide (NO) level, when compared with the saline group. In contrast, both treadmill exercise and/or FG protocols, in particular, the combined protocol, led to the improvement in HSP72 and balance in oxidant/antioxidant process and inhibited vascular dysfunction, when compared with the L-NAME group. Moreover, no significant differences were detected in the HSP72 level between rats in the treadmill exercise and FG groups. These results provide a rationale for an inhibitory role and a cardioprotective effect of lifestyle related to the health in the attenuation of hypertension-induced cardiotoxicity.

Interaction between overtraining and the interindividual variability may (not) trigger muscle oxidative stress and cardiomyocyte apoptosis in rats

Severe endurance training (overtraining) may cause underperformance related to muscle oxidative stress and cardiomyocyte alterations. Currently, such relationship has not been empirically established. In this study, Wistar rats (n = 19) underwent eight weeks of daily exercise sessions followed by three overtraining weeks in which the daily frequency of exercise sessions increased. After the 11th training week, eight rats exhibited a reduction of 38% in performance (nonfunctional overreaching group (NFOR)), whereas eleven rats exhibited an increase of 18% in performance (functional overreaching group (FOR)). The red gastrocnemius of NFOR presented significantly lower citrate synthase activity compared to FOR, but similar to that of the control. The activity of mitochondrial complex IV in NFOR was lower than that of the control and FOR. This impaired mitochondrial adaptation in NFOR was associated with increased antioxidant enzyme activities and increased lipid peroxidation (in muscle and plasma) relative to FOR and control. Cardiomyocyte apoptosis was higher in NFOR. Plasma creatine kinase levels were unchanged. We observed that some rats that presented evidence of muscle oxidative stress are also subject to cardiomyocyte apoptosis under endurance overtraining. Blood lipid peroxides may be a suitable biomarker for muscle oxidative stress that is unrelated to severe muscle damage.

Differential expression of caveolins and myosin heavy chains in response to forced exercise in rats

Exercise training can improve strength and lead to adaptations in the skeletal muscle and nervous systems. Skeletal muscles can develop into two types: fast and slow, depending on the expression pattern of myosin heavy chain (MHC) isoforms. Previous studies reported that exercise altered the distribution of muscle fiber types. It is not currently known what changes in the expression of caveolins and types of muscle fiber occur in response to the intensity of exercise. This study determined the changes in expression of caveolins and MHC type after forced exercise in muscular and non-muscular tissues in rats. A control (Con) group to which forced exercise was not applied and an exercise (Ex) group to which forced exercise was applied. Forced exercise, using a treadmill, was introduced at a speed of 25 m/min for 30 min, 3 times/day (07:00, 15:00, 23:00). Homogenized tissues were applied to extract of total RNA for further gene analysis. The expression of caveolin-3 and MHC2a in the gastrocnemius muscle of female rats significantly increased in the Ex group compared with the Con group (P<0.05). Furthermore, in the gastrocnemius muscle of male rats, the expression of MHC2x was significantly different between the two groups (P<0.05). There was an increased expression in caveolin-3 and a slightly decreased expression in TGFβ-1 in muscular tissues implicating caveolin-3 influences the expression of MHC isoforms and TGFβ-1 expression. Eventually, it implicates that caveolin-3 has positive regulatory function in muscle atrophy induced by neural dysfunction with spinal cord injury or stroke.

Effect of seabuckthorn (Hippophae rhamnoides ssp. sinensis) leaf extract on the swimming endurance and exhaustive exercise-induced oxidative stress of rats

BACKGROUND

Seabuckthorn (SBT) leaves have significant antioxidant, immunomodulatory and anti-inflammatory properties. The objective of this study was to assess the anti-fatigue, antioxidant and tissue-protective properties of aqueous lyophilised extracts of SBT dried leaves in the hearts of Wistar male rats undergoing exhaustive physical exercise. Doses of 50, 200 and 800 mg kg⁻¹ body weight (BW) day⁻¹ were given orally for 1 week. A week later the rats were forced to swim in barrels until they were exhausted. The times were noted to establish the effective dose of the extracts in rats. After establishing the effective dose, the rats were then sacrificed and assessed for various biochemical parameters.

RESULTS

SBT leaf aqueous extracts (200 and 800 mg kg⁻¹ BW) markedly prolonged the swim time of rats. Supplementation with SBT leaf aqueous extracts helped reduce the exhaustive exercise-induced increase in malondialdehyde level and selenium-dependent glutathione peroxidase activity. Alanine aminotransferase and creatine kinase levels were lowered in the exhaustive exercise with SBT treatment group (E + SBT) compared with the exhaustive exercise group (E).

CONCLUSION

The findings suggest that SBT leaf aqueous extract supplements can enhance exercise capacity and protect against oxidative damage caused by exhaustive exercise in rats.

High-dose testosterone propionate treatment reverses the effects of endurance training on myocardial antioxidant defenses in adolescent male rats

This study was aimed at evaluation of changes in activities of selected antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase) and contents of key nonenzymatic antioxidants (glutathione, protein thiol groups, and α- and γ-tocopherols) in the left heart ventricle of young male Wistar rats subjected to endurance training (treadmill running, 1 h daily, 5 days a week, for 6 weeks) or/and testosterone propionate treatment (8 or 80 mg/kg body weight, intramuscularly, once a week, for 6 weeks) during adolescence. The training alone increased the activities of key antioxidant enzymes, but lowered the pool of nonenzymatic antioxidants and enhanced myocardial oxidative stress as evidenced by elevation of the lipid peroxidation biomarker malondialdehyde. The lower-dose testosterone treatment showed mixed effects on the individual components of the antioxidant defense system, but markedly enhanced lipid peroxidation. The higher-dose testosterone treatment decreased the activities of the antioxidant enzymes, lowered the contents of the nonenzymatic antioxidants, except for that of γ-tocopherol, reversed the effect of endurance training on the antioxidant enzymes activities, and enhanced lipid peroxidation more than the lower-dose treatment. These data demonstrate the potential risk to cardiac health from exogenous androgen use, either alone or in combination with endurance training, in adolescents.

Effect of short- and long-term strength exercise on cardiac oxidative stress and performance in rat

Increase in heart metabolism during severe exercise facilitates production of ROS and result in oxidative stress. Due to shortage of information, the effect of chronic strength exercise on oxidative stress and contractile function of the heart was assessed to explore the threshold for oxidative stress in this kind of exercise training. Male Wistar rats (80) were divided into two test groups exercised 1 and 3 months and two control groups without exercise. Strength exercise was carried by wearing a Canvas Jacket with weights and forced rats to lift the weights. Rats were exercised at 70% of maximum lifted weight 6 days/week, four times/day, and 12 repetitions each time. Finally, the hearts of ten rats/group were homogenized and MDA, SOD, GPX, and catalase (CAT) were determined by ELISA method. In other ten rats/group, left ventricle systolic and end diastolic pressures (LVSP and LVEDP) and contractility indices (LVDP and +dp/dt max) and relaxation velocity (-dp/dt max) were recorded. The coronary outflow was collected. Short- and long-term strength exercise increased heart weight and heart/BW ratio (P < 0.05). In the 3-month exercise group, basal heart rate decreased (P < 0.05). LVEDP did not change but LVDP, +dp/dt max, -dp/dt max, and coronary flow significantly increased in both exercise groups (P < 0.05). None of MDA or SOD, GPX, and CAT significantly changed. The results showed that sub-maximal chronic strength exercise improves heart efficiency without increase in oxidative stress index or decrease in antioxidant defense capacity. These imply that long-time strength exercise up to this intensity is safe for cardiac health.

alpha-Lipoic acid supplementation enhances heat shock protein production and decreases post exercise lactic acid concentrations in exercised standardbred trotters

Heat shock protein (HSP) expression is an adaptive mechanism against the disruption of cell homeostasis during exercise. Several antioxidant supplementation strategies have been used to enhance tissue protection. In this study, we examined the effects of a redox modulator, alpha-lipoic acid (LA) on HSP responses in six standardbred trotters following intense aerobic exercise. DL-LA supplementation (25 mg kg(-1) d(-1)) for five weeks increased the resting levels of HSP90 (1.02+/-0.155 in control and 1.26+/-0.090 after supplementation in arbitrary units) and the recovery levels of inducible HSP70 (0.89+/-0.056 in control and 1.05+/-0.089 after supplementation in arbitrary units) in skeletal muscle. Furthermore, LA increased skeletal muscle citrate synthase activity at rest and lowered the blood lactate concentration during exercise without any changes in the heart rate. LA had no effect on concentrations of HSP60, HSP25 or GRP75 in skeletal muscle. LA decreased the exercise-induced increases in plasma aspartate aminotransferase and creatine kinase concentrations during recovery. Our results suggest that LA supplementation may enhance tissue protection and increase oxidative capacity of the muscle in horse.

Effect of different models of physical exercise on oxidative stress markers in mouse liver

The aim of this study was to investigate the effect of different protocols of physical exercise on oxidative stress markers in mouse liver. Twenty-eight male CF1 mice (30-35 g) were distributed into 4 groups (n = 7) - untrained (UT), continuous running (CR), downhill running (D-HR), and intermittent running (IR) - and underwent an 8-week training program. Forty-eight hours after the last training session, the animals were killed, and their livers were removed. Blood lactate, creatine kinase, citrate synthase, thiobarbituric acid reactive species, carbonyl, superoxide dismutase (SOD), and catalase (CAT) activities were assayed. Results show a decrease in the level of lipoperoxidation and protein carbonylation in the CR and D-HR groups. SOD activity was significantly increased and CAT activity was reduced in the CR and D-HR groups. Our findings indicate that CR and D-HR may be important for decreasing oxidative damage and in the regulation of antioxidant enzymes (SOD and CAT) in the livers of trained mice.

Heat shock proteins and exercise: a primer

Heat shock proteins (HSPs) are, in general, prosurvival molecules within the cellular environment, and the overexpression of even just 1 family of HSPs can lead to protection against and improvements after a variety of stressors. Not surprisingly, a fertile area of study has grown out of efforts to exploit the innate biologic behaviour of HSPs. Exercise, because of the inherent physiologic stresses associated with it, is but 1 stimulus that can result in a robust increase in various HSPs in several tissues, not the least of which happen to be the heart and skeletal muscle. The purpose of this review is to introduce the reader to the major HSP families, the control of their expression, and some of their biologic functions, specifically with respect to the influence of exercise. Moreover, as the first in a series of reviews from a common symposium, we will briefly introduce the concepts presented by the other authors, which include the effects of different exercise paradigms on skeletal muscle HSPs in the adult and aged systems, HSPs as regulators of inflammation, and the ion channel stabilizing effects of HSPs.

Increased temperature and protein oxidation lead to HSP72 mRNA and protein accumulation in the in vivo exercised rat heart

Expression of myocardial heat shock protein 72 (HSP72), mediated by its transcription factor, heat shock factor 1 (HSF1), increases following exercise. However, the upstream stimuli governing exercise-induced HSF1 activation and subsequent Hsp72 gene expression in the whole animal remain unclear. Exercise-induced increases in body temperature may promote myocardial radical production, leading to protein oxidation. Conceivably, myocardial protein oxidation during exercise may serve as an important signal to promote nuclear HSF1 migration and activation of Hsp72 expression. Therefore, these experiments tested the hypothesis that prevention of exercise-induced increases in body temperature attenuates cardiac protein oxidation, diminishes HSF1 activation and decreases HSP72 expression in vivo. To test this hypothesis, in vivo exercise-induced changes in body temperature were manipulated by exercising male rats in either cold (4 degrees C) or warm ambient conditions (22 degrees C). Warm exercise increased both body temperature (+3 degrees C) and myocardial protein oxidation, whereas these changes were attenuated by cold exercise. Interestingly, exercise in both conditions did not significantly increase myocardial nuclear localized phosphorylated HSF1. Nonetheless, warm exercise elevated left-ventricular HSP72 mRNA by ninefold and increased myocardial HSP72 protein levels by threefold compared with cold-exercised animals. Collectively, these data indicate that elevated body temperature and myocardial protein oxidation promoted exercise-induced cardiac HSP72 mRNA expression and protein accumulation following in vivo exercise. However, these results suggest that exercise-induced myocardial HSP72 protein accumulation is not a result of nuclear-localized, phosphorylated HSF1, indicating that other transcriptional or post-transcriptional regulatory mechanisms are involved in exercise-induced HSP72 expression.

Gene expression responses over 24 h to lengthening and shortening contractions in human muscle: major changes in CSRP3, MUSTN1, SIX1, and FBXO32

Resistance training using lengthening (eccentric) contractions induces greater increases in muscle size than shortening (concentric) contractions, but the underlying molecular mechanisms are not clear. Using temporal expression profiling, we compared changes in gene expression within 24 h of an acute bout of each type of contractions conducted simultaneously in the quadriceps of different legs. Five healthy young men performed shortening contractions with one leg while the contralateral leg performed lengthening contractions. Biopsies were taken from both legs before exercise and 3, 6, and 24 h afterwards, in the fed state. Expression profiling ( n = 3) was performed using a custom-made Affymetrix MuscleChip containing probe sets of ∼3,300 known genes and expressed sequence tags expressed in skeletal muscle. We identified 51 transcripts differentially regulated between the two exercise modes. Using unsupervised hierarchical clustering, we identified four distinct clusters, three of which corresponded to unique functional categories (protein synthesis, stress response/early growth, and sarcolemmal structure). Using quantitative RT-PCR ( n = 5), we verified expression changes (lengthening/shortening) in SIX1 (3 h, −1.9-fold, P < 0.001), CSRP3 (6 h, 2.9-fold, P < 0.05), and MUSTN1 (24 h, 4.3-fold, P < 0.05). We examined whether FBXO32/atrogin-1/MAFbx, a known regulator of protein breakdown and of muscle atrophy was differentially expressed: the gene was downregulated after lengthening contractions (3 h, 2.7-fold, P < 0.05; 6 h, 3.3-fold, P < 0.05; 24 h, 2.3-fold, P < 0.05). The results suggested that lengthening and shortening contractions activated distinct molecular pathways as early as 3 h postexercise. The molecular differences might contribute to mechanisms underlying the physiological adaptations seen with training using the two modes of exercise.

Short-Term Exercise Does Not Increase ER Stress Protein Expression in Cardiac Muscle

PURPOSE

Both short-term (three to five consecutive days) and long-term (weeks to months) endurance exercise training provides cardioprotection against ischemia-reperfusion (IR)-induced injury. However, the mechanisms responsible for exercise-induced cardioprotection are not well understood. Emerging evidence indicates that endoplasmic reticulum (ER) damage contributes to IR-induced myocardial injury. It follows that exercise-induced expression of ER stress proteins could serve as the mediators of exercise-induced cardioprotection against IR injury. Hence, these experiments tested the hypothesis that exercise training is associated with an increase in ER stress proteins in the heart.

METHODS

Adult male Sprague-Dawley rats (N=13) were habituated to treadmill running for 5 d, followed by five 60-min exercise bouts (approximately 70% of VO2max) on consecutive days. Infarct area resulting from IR was determined by a standard histological (triphenyltetrazolium chloride (TTC)) method. Cardiac levels of ER stress proteins Grp78, Grp94, and calreticulin were analyzed via Western blot. Moreover, we determined myocardial levels of heat shock protein 72 (HSP72) along with ER proteins associated with cellular injury, including CHOP, caspase 12, Puma, Noxa, and ATF3.

RESULTS

Our exercise protocol resulted in cardioprotection as evidenced by reduced infarct size (P<0.05) and increased myocardial HSP72 levels (+227%; P<0.01) in the exercise-trained animals. Nonetheless, exercise training did not increase (P>0.05) cardiac levels of the ER stress proteins, Grp78, Grp94, and calreticulin. Moreover, exercise did not alter myocardial levels of CHOP, caspase 12, Puma, Noxa, or ATF3.

CONCLUSION

These data reveal that short-term exercise training does not elevate ER stress proteins in the heart. Hence, the cardioprotective effect of short-term exercise training does not seem to be linked to ER stress adaptation.

Exercise training improves myocardial tolerance to ischemia in male but not in female rats

Acute exercise increases myocardial tolerance to ischemia-reperfusion (I-R) injury in male but not in female rat hearts, possibly due to a decreased heat shock protein 70 (Hsp70) response in the female hearts. This study examined whether repetitive exercise training would increase Hsp70 and myocardial tolerance to I-R injury in female rat hearts. Adaptations in myocardial manganese superoxide dismutase (MnSOD) and endothelial nitric oxide synthase (eNOS) were also assessed. Ten-week old male (M) and female (F) Sprague-Dawley rats ( n = 40 total) exercise-trained for 14 wk; the last 8 wk consisted of running 1 h at 30 m/min (2% incline), 5 days/wk. Following training, left ventricle mechanical function (LVMF) was monitored for 30 min of reperfusion following 30 min of global ischemia (Langendorff procedure). Myocardial Hsp70 content was not different in M and F control groups, while increases were observed in both trained groups (M greater than F; P < 0.05). Although MnSOD content did not differ between groups, endothelial nitric oxide synthase (eNOS) levels were decreased in F, with no change in M, following training ( P < 0.05). Hearts from control F demonstrated a greater recuperation of all indices of LVMF following I-R compared with control M hearts ( P < 0.05). Hearts of trained M exhibited improved recovery of LVMF (left ventricular diastolic pressure, left ventrcular end-diastolic pressure, +dP/d t, −dP/d t) during reperfusion compared with control M hearts ( P < 0.05). In contrast, hearts of trained F did not show any change in recovery from I-R. Hence, exercise training is more beneficial to M than F in improving myocardial function following I-R injury.

MRP1/GS-X pump ATPase expression: is this the explanation for the cytoprotection of the heart against oxidative stress-induced redox imbalance in comparison to skeletal muscle cells?

Striated muscle activity is always accompanied by oxidative stress (OxStress): the more intense muscle work and/or its duration, the more a redox imbalance may be attained. In spite of cardiac muscle functioning continuously, it is well known that the heart does not suffer from OxStress-induced damage over a broad physiological range. Although the expression of antioxidant enzymes may be of importance in defending heart muscle against OxStress, a series of combined antioxidant therapeutic approaches have proved to be mostly ineffective in avoiding cellular injury. Hence, additional mechanisms may be involved in heart cytoprotection other than antioxidant enzyme activities. The strong cardiotoxic effect of doxorubicin-induced cancer chemotherapy shed light on the possible role for multidrug resistance-associated proteins (MRP) in this context. Muscle activity-induced 'physiological' OxStress enhances the production of glutathione disulfide (GSSG) thus increasing the ratio of GSSG to glutathione (GSH) content inside the cells, which, in turn, leads to redox imbalance. Since MRP1 gene product (a GS-X pump ATPase) is a physiological GSSG transporter, adult Wistar rats were tested for MRP1 expression and activity in the heart and skeletal muscle (gastrocnemius), in as much as the latter is known to be extremely sensitive to muscle activity-induced OxS. MRP1 expression was completely absent in skeletal muscle. In contrast, the heart showed an exercise training-dependent induction of MRP1 protein expression which was further augmented (2.4-fold) as trained rats were challenged with a session of acute exercise. On the other hand, inducible expression of the 70-kDa heat shock protein (HSP70), a universal marker of cellular stress, was completely absent in the heart of sedentary and acutely exercised rats, whereas skeletal muscle showed a conspicuous exercise-dependent HSP70 expression, which decreased by 45% with exercise training. This effect was paralleled by a 58% decrease in GSH content in skeletal muscle which was even higher (an 80%-fall) after training thus leading to a marked redox imbalance ([GSSG]/[GSH] raised up to 38-fold). In the heart, GSH contents and [GSSG]/[GSH] ratio remained virtually unchanged even after exercise challenges, while GS-X pump activity was found to be 20% higher in the heart related to skeletal muscle. These findings suggest that an intrinsic higher capacity to express the MRP1/GS-X pump may dictate the redox status in the heart muscle thus protecting myocardium by preventing GSSG accumulation in cardiomyocytes as compared to skeletal muscle fibres.

Mild exercise training, cardioprotection and stress genes profile

To improve current knowledge of the molecular mechanisms underlying exercise-induced cardioprotection in a rat model of mild exercise training, Sprague-Dawley rats were trained to run on a treadmill up to 55% of their maximal oxygen uptake for 1 h/day, 3 days/week, 14 weeks, with age-matched sedentary controls (n = 20/group). Rats were sacrificed 48 h after the last training session. Despite lack of cardiac hypertrophy, training decreased blood hemoglobin (7.94 +/- 0.21 mM vs. 8.78 +/- 0.23 mM, mean +/- SE, P = 0.01) and increased both plasma malondialdehyde (0.139 +/- 0.005 mM vs. 0.085 +/- 0.009 mM, P = 0.05) and the activity of Mn-superoxide dismutase (11.6 +/- 0.6 vs. 16.5 +/- 1.6 mU/microg, P = 0.01), whereas total superoxide dismutase activity was unaffected. When subjected to 30-min ischemia followed by 90-min reperfusion, hearts from trained rats (n = 5) displayed reduced infarct size as compared to controls (37.26 +/- 0.92% vs. 49.09 +/- 2.11% of risk area, P = 0.04). The biochemical analyses in the myocardium, which included gene expression profiles, real-time PCR, Western blot and determination of enzymatic activity, showed training-induced upregulation of the following mRNAs and/or proteins: growth-arrest and DNA-damage induced 153 (GADD153/CHOP), heme-oxygenase-1 (HO-1), cyclooxygenase-2 (Cox-2), heat-shock protein 70/72 (HSP70/72), whereas heat-shock protein 60 (HSP60) and glucose-regulated protein 75 (GRP75) were decreased. As a whole, these data indicate that mild exercise training activates a second window of myocardial protection against ischemia/reperfusion by upregulating a number of protective genes, thereby warranting further investigation in man.

Effect of training and detraining on the expression of heat shock proteins in m. triceps brachii of untrained males and females

Forty untrained persons were randomized to four different training protocols that exercised the m. triceps brachii. Group 1 and 2 performed high intensity (HI) elbow extensions and group 3 and 4 performed low intensity (LI) elbow extensions. Group 1 and 3 trained until they had accumulated a matching high volume (HV) of training, while group 2 and 4 trained until they had accumulated a matching low volume (LV) of training. Training for 5-8 weeks increased the HSP72, HSP27 and GRP75 levels in the subjects' m. triceps brachii by 111, 71 and 192%, respectively (Fig. 1a-c). There were, however, no significant differences in the heat shock protein (HSP) responses to training between the four training groups (Fig. 2a-c). The frequency of extreme responses to exercise was, however, higher after HI exercise than after LI exercise, indicating that HI exercise induces extreme HSP reactions in some subjects. When we assigned the subjects to three clusters, according to the total number of repetitions they had lifted, the subjects who had lifted the highest number of repetitions had lower PostExc HSP levels compared with subjects that lifted the lowest number of repetitions (Fig. 3a-c). Additionally, there was a negative non-linear regression (Fig. 4a-c) between the subjects PreExc levels of HSP72, HSP27 and GRP75 and the percentage change in their respective protein concentration after training (r = -0.75, -0.89 and -0.88, all P < 0.0001). Thus, the PreExc level of HSPs seems to be an important "regulator" of HSP expression following the training.

Exercise training affects age-induced changes in SOD and heat shock protein expression in rat heart

The aim of this study was to test the effects of age and chronic exercise training on antioxidant and heat shock protein (Hsp) expression by comparing the hearts of young (Y), sedentary old (SO) and trained old (TO) rats. In SO rats, there were: (a) changes in myocardial structure and function; (b) increased malondialdehyde levels; (c) no changes in superoxide-dismutase (SOD) enzymes; (d) reduced Hsp70 expression; and (e) increased Hsp27 expression. In TO rats, SOD enzymes and Hsp70 expression were increased and Hsp27 was further increased. Malondialdehyde level did not differ between TO and SO rats, which shows that chronic exercise did not affect the peroxidation index. In summary, by increasing Hsp27 and Hs70 levels, prolonged exercise partially counterbalanced the heart age-related effects in the antioxidant system without altering peroxidation levels. These findings suggest that the beneficial effects on aged-related cardiovascular changes could be connected to the "anti-oxidant" effects of prolonged exercise training.

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

Myocardial injury is a major contributor to the morbidity and mortality associated with coronary artery disease. Regular exercise has been confirmed as a pragmatic countermeasure to protect against cardiac injury. Specifically, endurance exercise has been proven to provide cardioprotection against cardiac insults in both young and old animals. Proposed mechanisms to explain the cardioprotective effects of exercise are mediated, at least partially, by redox changes and include the induction of myocardial heat shock proteins, improved cardiac antioxidant capacity, and/or elevation of other cardioprotective molecules. Understanding the molecular basis for exercise-induced cardioprotection is important in developing exercise strategies to protect the heart during and after insults. Data suggest that these positive modulator effects occur at different levels of cellular organization, being mitochondria fundamental organelles that are sensitive to disturbances imposed by exercise on basal homeostasis. At present, which of these protective mechanisms is essential for exercise-induced cardioprotection remains unclear. This review analyzes the biochemical, morphological and functional outcomes of acute and chronic exercise on the overall cardiac muscle tissue and in isolated mitochondria. Some redox-based mechanisms behind the cross-tolerance effects particularly induced by endurance training, against certain stressors responsible for the impairments in cardiac homeostasis caused by aging, diabetes, drug administration or ischemia-reperfusion are also outlined. Further work should be addressed in order to clarify the precise regulatory mechanisms by which physical exercise augments heart tolerance against many cardiotoxic agents.

Effects of exercise and training in hypoxia on antioxidant/pro-oxidant balance

OBJECTIVE

The aim was to investigate the effects of acute exercise under hypoxic condition and the repetition of such exercise in a 'living low-training high' training on the antioxidant/prooxidant balance.

DESIGN

Randomized, repeated measures design.

SETTING

Faculté de Médecine, Clermont-Ferrand, France.

SUBJECTS

Fourteen runners were randomly divided into two groups. A 6-week endurance training protocol integrated two running sessions per week at the second ventilatory threshold into the usual training.

INTERVENTION

A 6-week endurance training protocol integrated two running sessions per week at the second ventilatory threshold into the usual training. The first hypoxic group (HG, n=8) carried out these sessions under hypoxia (3000 m simulated altitude) and the second normoxic group (NG, n=6) in normoxia. In control period, the runners were submitted to two incremental cycling tests performed in normoxia and under hypoxia (simulated altitude of 3000 m). Plasma levels of advanced oxidation protein products (AOPP), malondialdehydes (MDA) and lipid oxidizability, ferric-reducing antioxidant power (FRAP), lipid-soluble antioxidants (alpha-tocopherol and beta-carotene) normalized for triacyglycerols and cholesterol were measured before and after the two incremental tests and at rest before and after training.

RESULTS

No significant changes of MDA and AOPP level were observed after normoxic exercise, whereas hypoxic exercise induced a 56% rise of MDA and a 44% rise of AOPP. Plasma level of MDA and arterial oxygen hemoglobin desaturations after the acute both exercises were highly correlated (r=0.73). alpha-Tocopherol normalized for cholesterol and triacyglycerols increased only after hypoxic exercise (10-12%, P<0.01). After training, FRAP resting values (-21%, P<0.05) and alpha-tocopherol/triacyglycerols ratio (-24%, P<0.05) were diminished for HG, whereas NG values remained unchanged.

CONCLUSIONS

Intense exercise and hypoxia exposure may have a cumulative effect on oxidative stress. As a consequence, the repetition of such exercise characterizing the 'living low-training high' model has weakened the antioxidant capacities of the athletes.

SPONSORSHIP

International Olympic Committee and the Direction Régionale de la Jeunesse et des Sports de la Région Auvergne.

Endurance training limits the functional alterations of heart rat mitochondria submitted to in vitro anoxia-reoxygenation

BACKGROUND

Studies analysing the effect of endurance training on heart mitochondrial function submitted to in vitro anoxia-reoxygenation (A-R) are missing. The present study aimed to investigate the effect of moderate endurance treadmill training (14 weeks) against rat heart mitochondrial dysfunction induced by in vitro A-R.

METHODS

Respiratory parameters (state 3, state 4, ADP/O and respiratory control ratio-RCR) and oxidative damage markers (carbonyl groups and malondialdehyde) were determined in isolated mitochondria before and after 1 min anoxia followed by 4 min reoxygenation. Levels of heat shock protein 60 kDa (HSP60) and 70 kDa (HSP70) were measured before A-R in mitochondria and whole muscle homogenate, respectively.

RESULTS

A-R significantly impaired the rate of state 3 and state 4 respiration, as well as the RCR and ADP/O in the sedentary group. However, mitochondrial state 3 respiration was significantly higher in trained than in the sedentary group both before and after A-R. The impairments in RCR, ADP/O ratio and state 4 induced by A-R in sedentary group were significantly attenuated in endurance-trained group. The inhibition of state 4 induced by GDP was significantly higher in trained than in sedentary group. Oxidative modifications of mitochondrial proteins and phospholipids were found in sedentary group after A-R, although limited in trained group. Increased levels of mitochondrial HSP60 and tissue HSP70 accompanied the lower decrease in the respiratory function after A-R observed in trained group.

CONCLUSION

We therefore concluded that endurance training limited the impairments on rat heart mitochondria caused by the oxidant insult inflicted by in vitro A-R.

Heat shock-induced attenuation of hydroxyl radical generation and mitochondrial aconitase activity in cardiac H9c2 cells

A mild heat shock (hyperthermia) protects cells from apoptotic and necrotic deaths by inducing overexpression of various heat shock proteins (Hsps). These proteins, in combination with the activation of the nitric oxide synthase (NOS) enzyme, play important roles in the protection of the myocardium against a variety of diseases. In the present work we report that the generation of potent reactive oxygen species (ROS), namely ·OH in cardiac H9c2 cells, is attenuated by heat shock treatment (2 h at 42°C). Western blot analyses showed that heat shock treatment induced overexpression of Hsp70, Hsp60, and Hsp25. The observed ·OH was found to be derived from the superoxide (O2−·) generated by the mitochondria. Whereas the manganese superoxide dismutase (MnSOD) activity was increased in the heat-shocked cells, the mitochondrial aconitase activity was reduced. The mechanism of O2−· conversion into ·OH in mitochondria is proposed as follows. The O2−· leaked from the electron transport chain, oxidatively damages the mitochondrial aconitase, releasing a free Fe2+. The aconitase-released Fe2+combines with H2O2to generate ·OH via a Fenton reaction and the oxidized Fe3+recombines with the inactivated enzyme after being reduced to Fe2+by other cellular reductants, turning it over to be active. However, in heat-shocked cells, because of higher MnSOD activity, the excess H2O2causes irreversible damage to the mitochondrial aconitase enzyme, thus inhibiting its activity. In conclusion, we propose that attenuation of ·OH generation after heat shock treatment might play an important role in reducing the myocardial ischemic injury, observed in heat shock-treated animals.

Effects of endurance training and acute exhaustive exercise on antioxidant defense mechanisms in rat heart

We investigated whether 8-week treadmill training strengthens antioxidant enzymes and decreases lipid peroxidation in rat heart. The effects of acute exhaustive exercise were also investigated. Male rats (Rattus norvegicus, Sprague-Dawley strain) were divided into trained and untrained groups. Both groups were further divided equally into two groups where the rats were studied at rest and immediately after exhaustive exercise. Endurance training consisted of treadmill running 1.5 h day(-1), 5 days week(-1) for 8 weeks. For acute exhaustive exercise, graded treadmill running was conducted. Malondialdehyde level in heart tissue was not affected by acute exhaustive exercise in untrained and trained rats. The activities of glutathione peroxidase and glutathione reductase enzymes decreased by both acute exercise and training. Glutathione S-transferase and catalase activities were not affected. Total and non-enzymatic superoxide scavenger activities were not affected either. Superoxide dismutase activity decreased by acute exercise in untrained rats; however, this decrease was not observed in trained rats. Our results suggested that rat heart has sufficient antioxidant enzyme capacity to cope with exercise-induced oxidative stress, and adaptive changes in antioxidant enzymes due to endurance training are limited.

Voluntary physical exercise and coronary flow velocity reserve: a transthoracic colour Doppler echocardiography study in spontaneously hypertensive rats

In the present study, we have developed and demonstrated a coronary artery imaging protocol in rats using transthoracic high-frequency CDE (colour Doppler echocardiography) to investigate the potential direct effects of exercise on CFVR (coronary flow velocity reserve). SHR (spontaneously hypertensive rats) performed voluntary exercise for 6 weeks. Rats were then submitted to ultrasonographic examination and CFVR measurements. The LAD (left anterior descending coronary artery) was visualized using transthoracic CDE in a modified parasternal long-axis view. Doppler measurement was made in mid-LAD during baseline and adenosine-induced hyperaemic condition. Gene and protein expression in cardiac tissue were studied using real-time PCR and immunohistochemistry. Adenosine infusion significantly (P<0.001, as determined by ANOVA) decreased HR, without affecting blood pressure in anaesthetized SHR. A significantly greater adenosine dose-dependent response was seen in exercised rats compared with controls (P=0.02, as determined by ANOVA). The baseline flow velocity in mid-LAD was 0.33±0.06 and 0.41±0.14 m/s in the exercised and control animals respectively (P value was not significant). The maximum adenosine-induced response was reached at a dose of 140 μg·kg−1 of body weight·min−1, and CFVR averaged at 2.6±0.53 and 1.5±0.24 in exercised and control animals respectively (P<0.01). Gene expression of CuZnSOD was up-regulated by 21% in exercised animals compared with controls (1.1±0.16 compared with 0.89±0.09; P<0.01), whereas eNOS expression was unchanged. In conclusion, CFVR in rats can be non-invasively assessed using CDE with high feasibility. Physical exercise is associated with improved CFVR and antioxidative capacity in SHR.

Voluntary exercise protects against acute doxorubicin cardiotoxicity in the isolated perfused rat heart

The clinical use of doxorubicin (DOX) is limited by a dose-dependent cardiotoxicity. The purpose of this study was to determine whether voluntary exercise training would confer protection against DOX cardiotoxicity in the isolated perfused rat heart. Female Sprague-Dawley rats were randomly assigned to standard holding cages or cages with running wheels for 8 wk. Twenty-four hours after the sedentary (SED) or voluntary exercise (VEX) running period, rats were anesthetized with pentobarbital sodium, and hearts were isolated and perfused with oxygenated Krebs-Henseleit (KH) buffer at a constant flow of 15 ml/min. After a 20-min stabilization period, hearts were paced at 300 beats per minute and perfused with KH buffer containing 10 μM DOX for 60 min. A set of control hearts from SED and VEX rats were perfused under identical conditions without DOX for the same period. DOX perfusion led to significant decreases in left ventricular developed pressure, +dP/d t, and −dP/d t, and significant increases in LV lipid peroxidation in sedentary rats compared with non-DOX controls ( P < 0.05). Prior voluntary exercise training attenuated these DOX-induced effects and was associated with a significant increase (78%, P < 0.05) in heat shock protein (HSP72), but not mitochondrial isoform of SOD (MnSOD) or CuZnSOD protein expression in the hearts of wheel-run animals. These data indicate that chronic physical activity may provide resistance against the cardiac dysfunction and oxidative damage associated with DOX exposure and provide novel evidence of HSP72 induction in the heart after voluntary exercise.

Endurance training attenuates doxorubicin-induced cardiac oxidative damage in mice

BACKGROUND

There is a lack of studies reporting the influence of DOX treatment on chronically exercised animals. This study intended to determine the effect of endurance swimming training on cardiac muscle tolerance to in vivo DOX-induced damage, analyzing the levels of oxidative stress markers, the response of antioxidant system and the expression of 60 and 70 kDa heat shock proteins (HSP).

METHODS

Forty-four Charles River CD1 male mice were randomly assigned to either non-trained placebo (NT+P) and non-trained DOX (NT+DOX) or trained placebo (T+P) and trained DOX (T+DOX). Twenty-four hours after completion of a 14-week training, cardiac ventricles were extracted for biochemical assays of oxidative stress and damage markers, antioxidant enzymes and HSPs.

RESULTS

DOX treatment per se (single 20 mg kg(-1) dose), administrated 24 h after the last exercise bout, elevated (p<0.05) plasma cardiac troponin I (cTnI), HSP60, % oxidized glutathione, thiobarbituric acid reactive substances and carbonyl groups and reduced -SH groups. However, training induced a significant increase (p<0.05) on total and reduced glutathione (GSH), HSP60 expression, and decreased the rise of plasma cTnI as well as cardiac carbonyl groups contents in DOX hearts, when compared to NT+DOX mice. Although catalase activity of T+DOX was significantly higher than T+P, no changes were observed in the activities of superoxide dismutase, glutathione peroxidase and glutathione reductase. Neither DOX nor training induced significant variations in HSP70.

CONCLUSION

Training improved myocardial tolerance to DOX-induced damage. It is likely that the improvement in responses to DOX was related to training-induced increases in GSH and HSP60.

Habitual exercise program protects murine intestinal, skeletal, and cardiac muscles against aging

Aging and aerobic exercise are two conditions known to interfere with health and quality of life, most likely by inducing oxidative stress to the organism. We studied the effects of aging on the morphological and functional properties of skeletal, cardiac, and intestinal muscles and their corresponding oxidative status in C57BL/6 mice and investigated whether a lifelong moderate exercise program would exert a protective effect against some deleterious effects of aging. As expected, aged animals presented a significant reduction of physical performance, accompanied by a decrease of gastrocnemius cross-sectional area and cardiac hypertrophy. However, most interesting was that aging dramatically interfered with the intestinal structure, causing a significant thickening of the ileum muscular layer. Senescent intestinal myocytes displayed many mitochondria with disorganized cristae and the presence of cytosolic lamellar corpuscles. Lipid peroxidation of ileum and gastrocnemius muscle, but not of the heart, increased in aged mice, thus suggesting enhanced oxidative stress. With exception of the intestinal muscle responsiveness, animals submitted to a daily session of 60 min, 5 days/wk, at 13 up to 21 m/min of moderate running in treadmill during animal life span exhibited a reversion of all the observed aging effects on intestinal, skeletal, and heart muscles. The introduction of this lifelong exercise protocol prevented the enhancement of lipid peroxidation and sarcopenia and also preserved cellular and ultracellular structures of the ileum. This is the first time that the protective effect of a lifelong regular aerobic physical activity against the deleterious effects of aging on intestinal muscle was demonstrated.

Moderate endurance training prevents doxorubicin-induced in vivo mitochondriopathy and reduces the development of cardiac apoptosis

The objective of this work was to test the hypothesis that endurance training may be protective against in vivo doxorubicin (DOX)-induced cardiomyopathy through mitochondria-mediated mechanisms. Forty adult (6-8 wk old) male Wistar rats were randomly divided into four groups (n = 10/group): nontrained, nontrained + DOX treatment (20 mg/kg), trained (14 wk of endurance treadmill running, 60-90 min/day), and trained + DOX treatment. Mitochondrial respiration, calcium tolerance, oxidative damage, heat shock proteins (HSPs), antioxidant enzyme activity, and apoptosis markers were evaluated. DOX induces mitochondrial respiratory dysfunction, oxidative damage, and histopathological lesions and triggers apoptosis (P < 0.05, n = 10). However, training limited the decrease in state 3 respiration, respiratory control ratio (RCR), uncoupled respiration, aconitase activity, and protein sulfhydryl content caused by DOX treatment and prevented the increased sensitivity to calcium in nontrained + DOX-treated rats (P < 0.05, n = 10). Moreover, training inhibited the DOX-induced increase in mitochondrial protein carbonyl groups, malondialdehyde, Bax, Bax-to-Bcl-2 ratio, and tissue caspase-3 activity (P < 0.05, n = 10). Training also increased by approximately 2-fold the expression of mitochondrial HSP-60 and tissue HSP-70 (P < 0.05, n = 10) and by approximately 1.5-fold the activity of mitochondrial and cytosolic forms of SOD (P < 0.05, n = 10). We conclude that endurance training protects heart mitochondrial respiratory function from the toxic effects of DOX, probably by improving mitochondrial and cell defense systems and reducing cell oxidative stress. In addition, endurance training limited the DOX-triggered apoptosis.

Antioxidants and ecto-5'-nucleotidase are not involved in the training-induced cardioprotection against ischaemia-reperfusion injury

Isolated Langendorff-perfused hearts from sedentary and prolonged (24 weeks) treadmill-trained rats were subjected to 30 min of normoxic perfusion either alone or followed by 20 min of global ischaemia, or by 20 min of global ischaemia and 15 min of normoxic reperfusion. Pre-ischaemic values of antioxidant enzyme activities and ecto-5'-nucleotidase activity were not different in sedentary and trained hearts but a 5-fold increase of 72-kDa heat shock protein (HSP72) levels was detected in trained myocardium. After ischaemia and reperfusion (I/R), metabolic recovery was better in trained than in sedentary hearts as indicated by higher ATP and creatine phosphate levels. However, antioxidant enzymatic activities, glutathione reductase, and total and mitochondrial superoxide dismutase decreased in trained rats after I/R, whereas they remained unchanged in the sedentary ones. Ecto-5'-nucleotidase activity was modified by I/R in sedentary as well as in trained hearts while HSP72 content did not change. Ecto-5'-nucleotidase activity and HSP72 content increased in parallel by the 30-min perfusion period. In conclusion, the cardioprotection induced by long-term training could be mediated by the exercise-induced increase in HSP72 levels and is not related to enhanced antioxidant systems or ecto-5'-NT activity.