Glutathione status and reactive oxygen generation in tissues of young and old exercised rats

Neuromechanism, recovery effect and case study of swimming training intervention in children with cerebral palsy: A case report

BACKGROUND

Cerebral palsy, hereinafter referred to as "cerebral palsy", refers to a non progressive injury that occurs during the development of brain tissue in fetuses or infants. The patients often have walking dysfunction, abnormal balance ability and abnormal body stability, which are mainly caused by Cranial nerves injury.

PATIENT CONCERNS

One child diagnosed with ataxia cerebral palsy by the hospital was recruited, aged 6 years and 9 months. The symptoms were: lower limb adduction and internal rotation, left neck tilt to the left due to insufficient muscle tension, and eyes squint to the right. The movement is clumsy and the coordination ability of limbs is poor; Its body balance function is poor, the sitting and standing position cannot keep the body upright and balanced for a long time, and the coordination of the random movement of hands and eyes is poor; Weak spatial cognition and orientation ability; Have persistent central motor dysfunction. When walking, the body leans forward and sideways, and the gait is staggered, which is easy to fall; In terms of expression, it shows vague language and unclear speech; Relatively retarded in intelligence.

DIAGNOSIS AND INTERVENTION

The study used swimming training intervention to report a twelve months training intervention program for a child with ataxic cerebral palsy, and evaluated it with Berg balance scale and modified Ashworth scale.

OUTCOMES

Swimming training has a significant effect on the rehabilitation of children with ataxic cerebral palsy; The forces from different directions in the water can improve the balance of children with cerebral palsy; Muscle endurance training with medium load intensity can help restore unilateral muscle tension deficiency to a certain extent, and make bilateral muscle tension gradually becomes.consistent, thus enhancing the balance ability, gait and body stability of children with cerebral palsy.

Impact of cancer cachexia on respiratory muscle function and the therapeutic potential of exercise

Cancer cachexia is defined as a multi-factorial syndrome characterised by an ongoing loss of skeletal muscle mass and progressive functional impairment, estimated to affect 50-80% of patients and responsible for 20% of cancer deaths. Elevations in the morbidity and mortality rates of cachectic cancer patients has been linked to respiratory failure due to atrophy and dysfunction of the ventilatory muscles. Despite this, there is a distinct scarcity of research investigating the structural and functional condition of the respiratory musculature in cancer, with the majority of studies exclusively focusing on limb muscle. Treatment strategies are largely ineffective in mitigating the cachectic state. It is now widely accepted that an efficacious intervention will likely combine elements of pharmacology, nutrition and exercise. However, of these approaches, exercise has received comparatively little attention. Therefore, it is unlikely to be implemented optimally, whether in isolation or combination. In consideration of these limitations, the current review describes the mechanistic basis of cancer cachexia and subsequently explores the available respiratory- and exercise-focused literature within this context. The molecular basis of cachexia is thoroughly reviewed. The pivotal role of inflammatory mediators is described. Unravelling the mechanisms of exercise-induced support of muscle via antioxidant and anti-inflammatory effects in addition to promoting efficient energy metabolism via increased mitochondrial biogenesis, mitochondrial function and muscle glucose uptake provide avenues for interventional studies. Currently available pre-clinical mouse models including novel transgenic animals provide a platform for the development of multi-modal therapeutic strategies to protect respiratory muscles in people with cancer.

Adropin increases with swimming exercise and exerts a protective effect on the brain of aged rats

Adropin is a protein in the brain that decreases with age. Exercise has a protective effect on the endothelium by increasing the level of adropin in circulation. In this study, whether adropin, whose level in the brain decreases with age, may increase with swimming exercise, and exhibit a protective effect was investigated. Young and aged male Sprague Dawley rats were submitted to 1 h of swimming exercise every day for 8 weeks. Motor activity parameters were recorded at the end of the exercise or waiting periods before the animals were euthanized. Increased motor functions were observed in only the young rats that exercised regularly. Adropin levels in the plasma, and the adropin and VEGFR2 immunoreactivities and p-Akt (Ser473) levels in the frontal cortex were significantly increased in the aged rats that exercised regularly. It was also observed that the BAX/Bcl2 ratio and ROS-RNS levels decreased, while the TAC levels increased in the aged rats that exercised regularly. The results of the study indicated that low-moderate chronic swimming exercise had protective effects by increasing the level of adropin in the frontal cortex tissues of the aged rats. Adropin is thought to achieve this effect by increasing the VEGFR2 expression level and causing Akt (Ser473) phosphorylation. These results indicated that an exercise-mediated increase in endogenous adropin may be effective in preventing the destructive effects of aging on the brain.

The Therapeutic Role of Exercise and Probiotics in Stressful Brain Conditions

Oxidative stress has been recognized as a contributing factor in aging and in the progression of multiple neurological disorders such as Parkinson’s disease, Alzheimer’s dementia, ischemic stroke, and head and spinal cord injury. The increased production of reactive oxygen species (ROS) has been associated with mitochondrial dysfunction, altered metal homeostasis, and compromised brain antioxidant defence. All these changes have been reported to directly affect synaptic activity and neurotransmission in neurons, leading to cognitive dysfunction. In this context two non-invasive strategies could be employed in an attempt to improve the aforementioned stressful brain status. In this regard, it has been shown that exercise could increase the resistance against oxidative stress, thus providing enhanced neuroprotection. Indeed, there is evidence suggesting that regular physical exercise diminishes BBB permeability as it reinforces antioxidative capacity, reduces oxidative stress, and has anti-inflammatory effects. However, the differential effects of different types of exercise (aerobic exhausted exercise, anaerobic exercise, or the combination of both types) and the duration of physical activity will be also addressed in this review as likely determinants of therapeutic efficacy. The second proposed strategy is related to the use of probiotics, which can also reduce some biomarkers of oxidative stress and inflammatory cytokines, although their underlying mechanisms of action remain unclear. Moreover, various probiotics produce neuroactive molecules that directly or indirectly impact signalling in the brain. In this review, we will discuss how physical activity can be incorporated as a component of therapeutic strategies in oxidative stress-based neurological disorders along with the augmentation of probiotics intake.

Effects of exercise training on the glutathione antioxidant system

Purpose

The glutathione (GSH) antioxidant system has been shown to play an important role in the maintenance of good health and disease prevention. Various approaches have been used to enhance GSH availability including diet, nutritional supplementation, and drug administration, with minor to moderate success. Exercise training has evolved as a new approach. The purpose of this study was to investigate the effects of aerobic exercise training (AET), circuit weight training (CWT), and combined training (AET + CWT) on general adaptations, and resistance to acutely induced oxidative stress, as assessed by changes in the GSH antioxidant system.

Methods

Eighty healthy sedentary volunteers participated in the study who were randomly assigned to four groups: control (no exercise); AET, CWT, and AET + CWT. Exercise training programs were designed to simulate outpatient cardiac rehabilitation (40 min × 3 days × 6 weeks). Venous blood sampling was taken at rest and post maximal graded exercise test (GXT). A new improved spectrophotometric venous assay analysis technique was used. A mixed model repeated measures analysis of variance design was used with t-tests for preplanned comparisons evaluated at Bonferroni-adjusted α levels.

Results

Effectiveness of the exercise training programs was demonstrated by significant between-group (exercise group versus control) comparisons. AET, CWT, and AET + CWT showed significant pretraining-posttraining increases in resting GSH and glutathione-glutathione disulfide ratio (GSH:GSSG), and significant decreases in GSSG levels ( P <0.005). AET + CWT showed the most pronounced effect compared with AET or CWT alone ( P <0.025).

Conclusion

This study represents the first longitudinal investigation involving the effects of multiple modes of exercise training on the GSH antioxidant system with evidence, suggesting the GHS:GSSG ratio as the most sensitive change marker. The significant findings of this study have potential clinical implications to individuals involved in cardiac and pulmonary rehabilitation. Eur J Cardiovasc Prev Rehabil 14:630-637 © 2007 The European Society of Cardiology

Molecular Aspects of Exercise-induced Cardiac Remodeling

Exercise-induced cardiac remodeling is typically an adaptive response associated with cardiac myocyte hypertrophy and renewal, increased cardiac myocyte contractility, sarcomeric remodeling, cell survival, metabolic and mitochondrial adaptations, electrical remodeling, and angiogenesis. Initiating stimuli/triggers of cardiac remodeling include increased hemodynamic load, increased sympathetic activity, and the release of hormones and growth factors. Prolonged and strenuous exercise may lead to maladaptive exercise-induced cardiac remodeling including cardiac dysfunction and arrhythmia. In addition, this article describes novel therapeutic approaches for the treatment of heart failure that target mechanisms responsible for adaptive exercise-induced cardiac remodeling, which are being developed and tested in preclinical models.

Blood reflects tissue oxidative stress: a systematic review

We examined whether the levels of oxidative stress biomarkers measured in blood reflect the tissue redox status. Data from studies that measured redox biomarkers in blood, heart, liver, kidney and skeletal muscle were analyzed. In seven out of nine investigated redox biomarkers (malondialdehyde, reduced glutathione, superoxide dismutase, catalase, glutathione peroxidase, vitamin C and E) there was generally good qualitative and quantitative agreement between the blood and tissues. In contrast, oxidized glutathione and the reduced to oxidized glutathione ratio showed poor agreement between the blood and tissues. This study suggests that most redox biomarkers measured in blood adequately reflect tissue redox status.

Effects of vitamin C and E supplementation on endogenous antioxidant systems and heat shock proteins in response to endurance training

Reactive oxygen and nitrogen species are important signal molecules for adaptations to training. Due to the antioxidant properties of vitamin C and E, supplementation has been shown to blunt adaptations to endurance training. In this study, we investigated the effects of vitamin C and E supplementation and endurance training on adaptations in endogenous antioxidants and heat shock proteins (HSP). Thirty seven males and females were randomly assigned to receive Vitamin C and E (C + E; C: 1000 mg, E: 235 mg daily) or placebo (PLA), and underwent endurance training for 11 weeks. After 5 weeks, a subgroup conducted a high intensity interval session to investigate acute stress responses. Muscle and blood samples were obtained to investigate changes in proteins and mRNA related to the antioxidant and HSP system. The acute response to the interval session revealed no effects of C + E supplementation on NFκB activation. However, higher stress responses to exercise in C + E group was indicated by larger translocation of HSPs and a more pronounced gene expression compared to PLA. Eleven weeks of endurance training decreased muscle GPx1, HSP27 and αB‐crystallin, while mnSOD, HSP70 and GSH remained unchanged, with no influence of supplementation. Plasma GSH increased in both groups, while uric acid decreased in the C + E group only. Our results showed that C + E did not affect long‐term training adaptations in the antioxidant‐ and HSP systems. However, the greater stress responses to exercise in the C + E group might indicate that long‐term adaptations occurs through different mechanisms in the two groups.

Reactive oxygen species are important signal molecules for adaptations to training. Previously vitamin C and E supplements has been shown to blunt adaptations to endurance training. In this study, we investigated the effects of vitamin C and E supplementation and endurance training on adaptations in endogenous antioxidants and heat shock proteins.

Cancer cachexia prevention via physical exercise: molecular mechanisms

Cancer cachexia is a debilitating consequence of disease progression, characterised by the significant weight loss through the catabolism of both skeletal muscle and adipose tissue, leading to a reduced mobility and muscle function, fatigue, impaired quality of life and ultimately death occurring with 25-30 % total body weight loss. Degradation of proteins and decreased protein synthesis contributes to catabolism of skeletal muscle, while the loss of adipose tissue results mainly from enhanced lipolysis. These mechanisms appear to be at least, in part, mediated by systemic inflammation. Exercise, by virtue of its anti-inflammatory effect, is shown to be effective at counteracting the muscle catabolism by increasing protein synthesis and reducing protein degradation, thus successfully improving muscle strength, physical function and quality of life in patients with non-cancer-related cachexia. Therefore, by implementing appropriate exercise interventions upon diagnosis and at various stages of treatment, it may be possible to reverse protein degradation, while increasing protein synthesis and lean body mass, thus counteracting the wasting seen in cachexia.

Repeated short-term daily exercise ameliorates oxidative cerebral damage and the resultant motor dysfunction after transient ischemia in rats

Long-term exercise prior to brain ischemia enhances the activities of antioxidant enzymes and leads to a significant reduction in brain damage and neurological deficits in rats subjected to transient middle cerebral artery occlusion. However, it has not been established whether relatively short-term exercise generates similar results following middle cerebral artery occlusion. We aimed to determine whether short-term exercise could reduce oxidative damage and prevent sensori-motor dysfunction. Male Wistar rats were subjected to perform daily exercise on a treadmill for 30 min at a speed of 15 m/min for 3 weeks, followed by a 90-min middle cerebral artery occlusion. Animals were assessed after middle cerebral artery occlusion for neurological deficits and sensori-motor function. Brain tissues were processed to evaluate infarct volume and oxidative damage. Oxidative stress was assessed using immunohistochemistry for 4-hydroxy-2-nonenal-modified proteins and 8-hydroxy-2'-deoxyguanosine. Antioxidant enzymes were evaluated using immunohistochemistry for thioredoxin and activity assay for superoxide dismutase. Exercise for 3 weeks decreased the severity of paralysis and impairment in forelimb motor coordination. Furthermore, exercise had effect on superoxide dismutase and reduced the infarct volume and the number of cells immunopositive for 4-hydroxy-2-nonenal-modified proteins and 8-hydroxy-2'-deoxyguanosine. Our results suggest that pre-conditioning treadmill exercise for 3 weeks is useful for ameliorating ischemia-induced brain injury.

Does exercise reduce brain oxidative stress? A systematic review

The aim of the present systematic review was to investigate the influence of different exercise programs on brain oxidative stress. A search of the literature was conducted up to 1 December 2012 across five databases: PUBMED, SCOPUS, SPORTS DISCUS, Web of Science, and The Cochrane Library. The search strategy used in the electronic databases mentioned was established as: (swim* OR exercise OR training) AND ("oxidative stress" AND brain) for each database. A methodological quality assessment valuation/estimation was additionally carried out in the final sample of studies. Of 1553 potentially eligible papers, 19 were included after inclusion and exclusion criteria. The methodological quality assessment showed a total score in the Quality Index between 40% and 80%, with a mean quality of 56.8%. Overall, regular moderate aerobic exercise appears to promote antioxidant capacity on brain. In contrast, anaerobic or high-intensity exercise, aerobic-exhausted exercise, or the combination of both types of training could deteriorate the antioxidant response. Future investigations should be focused on establishing a standardized exercise protocol, depending on the exercise metabolism wanted to test, which could enhance the objective knowledge in this topic.

Exercise-induced adaptations of cardiac redox homeostasis and remodeling in heterozygous SOD2-knockout mice

A reduced expression of the manganese-dependent superoxide dismutase (SOD2) is characterized by increased cardiac oxidative stress. Oxidative stress has also been described in situations of physical exercise. We investigated the influence of physical exercise (EX; treadmill 1 h/day at 15 m/min, 5 days/wk, at an angle of 5° for a duration of 8 wk) on cardiac function [heart frequency (HF), echocardiography, morphometry], oxidative stress [reactive oxygen species (ROS)], and antioxidative defence capacity (peroxiredoxin 1–6) in male SOD2-knockout (SOD2_EX) and wild-type mice (WT_EX) compared with untrained age-matched animals (WT_CON; SOD2_CON). In SOD2_CON, heart weight, cardiomyocyte diameter, and cardiac ROS were significantly larger and peroxiredoxin isoforms 4–6 lower than in WT_CON. The vessel-to-cardiomyocyte ratio, cardiac VEGF-concentration, and cardiac function were similar in SOD2_CON and WT_CON. Both groups tolerated the exercise protocol well. In WT, exercise significantly increased vessel-to-cardiomyocyte ratio and ROS-generation and downregulated peroxiredoxin isoforms 4–6 and VEGF generation. The vessel-to-cardiomyocyte ratio, cardiac VEGF concentration, and cardiac ROS were not altered in SOD2_EX compared with SOD2_CON, but a significant upregulation of cardiac peroxiredoxin 1 and 4 was observed. Similar to the result observed in WT_EX, peroxiredoxin 3 was upregulated in SOD2_EX. Chronic exercise shifted the (mal)adaptive hypertrophic into a compensated dilated cardiac phenotype in SOD2_EX. In conclusion, downregulation of SOD2 induces a maladaptive cardiac hypertrophy. In this situation, physical exercise results in a further deterioration of cardiac remodeling despite an upregulation of the antioxidative defense system.

Reactive oxygen species: impact on skeletal muscle

It is well established that contracting muscles produce both reactive oxygen and nitrogen species. Although the sources of oxidant production during exercise continue to be debated, growing evidence suggests that mitochondria are not the dominant source. Regardless of the sources of oxidants in contracting muscles, intense and prolonged exercise can result in oxidative damage to both proteins and lipids in the contracting myocytes. Further, oxidants regulate numerous cell signaling pathways and modulate the expression of many genes. This oxidant-mediated change in gene expression involves changes at transcriptional, mRNA stability, and signal transduction levels. Furthermore, numerous products associated with oxidant-modulated genes have been identified and include antioxidant enzymes, stress proteins, and mitochondrial electron transport proteins. Interestingly, low and physiological levels of reactive oxygen species are required for normal force production in skeletal muscle, but high levels of reactive oxygen species result in contractile dysfunction and fatigue. Ongoing research continues to explore the redox-sensitive targets in muscle that are responsible for both redox regulation of muscle adaptation and oxidant-mediated muscle fatigue.

Nigella sativa: reduces the risk of various maladies

Coinage of terms like nutraceuticals, functional, and pharma foods has diverted the attention of human beings to where they are seeking more natural cures. Though pharmaceutical drugs have been beneficial for human health and have cured various diseases but they also impart some side effects. Numerous plants have been tested for their therapeutic potential; Nigella sativa, commonly known as black cumin, is one of them. It possesses a nutritional dense profile as its fixed oil (lipid fraction), is rich in unsaturated fatty acids while essential oil contains thymoquinone and carvacrol as antioxidants. N. sativa seeds also contain proteins, alkaloids (nigellicines and nigelledine), and saponins (alpha-hederin) in substantial amounts. Recent pharmacological investigations suggested its potential role, especially for the amelioration of oxidative stress through free radical scavenging activity, the induction of apoptosis to cure various cancer lines, the reduction of blood glucose, and the prevention of complications from diabetes. It regulates hematological and serological aspects and can be effective in dyslipidemia and respiratory disorders. Moreover, its immunopotentiating and immunomodulating role brings balance in the immune system. Evidence is available supporting the utilization of Nigella sativa and its bioactive components in a daily diet for health improvement. This review is intended to focus on the composition of Nigella sativa and to elaborate its possible therapeutic roles as a functional food to prevent an array of maladies.

Clinical cardioprotection and the value of conditioning responses

Adjunctive cardioprotective strategies for ameliorating the reversible and irreversible injuries with ischemia-reperfusion (I/R) are highly desirable. However, after decades of research, the promise of clinical cardioprotection from I/R injury remains poorly realized. This may arise from the challenges of trialing and effectively translating experimental findings from laboratory models to patients. One can additionally consider whether features of the more heavily focused upon candidates could limit or preclude therapeutic utility and thus whether we might shift attention to alternate strategies. The phenomena of preconditioning and postconditioning have proven fertile in identification of experimental means of cardioprotection and are the most intensely interrogated responses in the field. However, there is evidence these processes, which share common molecular signaling elements and end effectors, may be poor choices for clinical exploitation. This includes evidence of age dependence, limiting efficacy in target aged or senescent hearts; refractoriness to conditioning stimuli in diseased myocardium; interference from a variety of relevant pharmaceuticals; inadvertent induction of these responses by prior ischemia or commonly used drugs, precluding further benefit; and sex dependence of protective signaling. This review focuses on these features, raising questions about current research strategies, and the suitability of these widely studied phenomena as rational candidates for clinical translation.

Exercise-induced oxidative stress: cellular mechanisms and impact on muscle force production

The first suggestion that physical exercise results in free radical-mediated damage to tissues appeared in 1978, and the past three decades have resulted in a large growth of knowledge regarding exercise and oxidative stress. Although the sources of oxidant production during exercise continue to be debated, it is now well established that both resting and contracting skeletal muscles produce reactive oxygen species and reactive nitrogen species. Importantly, intense and prolonged exercise can result in oxidative damage to both proteins and lipids in the contracting myocytes. Furthermore, oxidants can modulate a number of cell signaling pathways and regulate the expression of multiple genes in eukaryotic cells. This oxidant-mediated change in gene expression involves changes at transcriptional, mRNA stability, and signal transduction levels. Furthermore, numerous products associated with oxidant-modulated genes have been identified and include antioxidant enzymes, stress proteins, DNA repair proteins, and mitochondrial electron transport proteins. Interestingly, low and physiological levels of reactive oxygen species are required for normal force production in skeletal muscle, but high levels of reactive oxygen species promote contractile dysfunction resulting in muscle weakness and fatigue. Ongoing research continues to probe the mechanisms by which oxidants influence skeletal muscle contractile properties and to explore interventions capable of protecting muscle from oxidant-mediated dysfunction.

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.

Carnitine and Lipoic Acid Alleviates Protein Oxidation in Heart Mitochondria During Aging Process

Oxidative modification alters the function of proteins and is thought to play an important role in the decline of cellular function during aging process. In the present study, we have evaluated the levels of oxidant production, protein oxidation, reduced and oxidized glutathione in young, middle aged and aged rats. The animals were divided into six groups, each group consisting of six animals each. Groups I and II were young rats, Groups III and IV were middle-aged rats and Groups V and VI were aged rats. Groups II, IV and VI were treated with carnitine (300 mg/kg bw) and Dl-alpha-Lipoic acid (100 mg/kg bw) for 28 days. Statistical significance was carried out using ANOVA. There was a significant reduction in the levels of reduced glutathione and Redox ratio (P<0.05) in aged rats whereas elevation in the levels of oxidant production, protein carbonyls, advanced oxidation protein products and oxidized glutathione were observed. Co-supplementation of carnitine and lipoic acid improved these levels to near normalcy. Thus we conclude that the utilization of carnitine and lipoic acid will lead to an improvement in the quality of living during the later stages of life by preventing free radical induced damage to the proteins.

Exercise by lifelong voluntary wheel running reduces subsarcolemmal and interfibrillar mitochondrial hydrogen peroxide production in the heart

Evidence suggests that mitochondrial dysfunction and oxidant production, in association with an accumulation of oxidative damage, contribute to the aging process. Regular physical activity can delay the onset of morbidity, increase mean lifespan, and reduce the risk of developing several pathological states. No studies have examined age-related changes in oxidant production and oxidative stress in both subsarcolemmal (SSM) and interfibrillar (IFM) mitochondria in combination with lifelong exercise. Therefore, we investigated whether long-term voluntary wheel running in Fischer 344 rats altered hydrogen peroxide (H2O2) production, antioxidant defenses, and oxidative damage in cardiac SSM and IFM. At 10–11 wk of age, rats were randomly assigned to one of two groups: sedentary and 8% food restriction (sedentary; n = 20) or wheel running and 8% food restriction (runners; n = 20); rats were killed at 24 mo of age. After the age of 6 mo, running activity was maintained at an average of 1,145 ± 248 m/day. Daily energy expenditure determined by doubly labeled water technique showed that runners expended on average ∼70% more energy per day than the sedentary rats. Long-term voluntary wheel running significantly reduced H2O2production from both SSM (−10.0%) and IFM (−9.6%) and increased daily energy expenditure (kJ/day) significantly in runners compared with sedentary controls. Additionally, MnSOD activity was significantly lowered in SSM and IFM from wheel runners, which may reflect a reduction in mitochondrial superoxide production. Activities of the other major antioxidant enzymes (glutathione peroxidase and catalase) and glutathione levels were not altered by wheel running. Despite the reduction in mitochondrial oxidant production, no significant differences in oxidative stress levels (4-hydroxy-2-nonenal-modified proteins, protein carbonyls, and malondialdehyde) were detected between the two groups. The health benefits of chronic exercise may be, at least partially, due to a reduction in mitochondrial oxidant production; however, we could not detect a significant reduction in several selected parameters of oxidative stress.

Biochemical evaluation of antioxidant function after a controlled optimum physical exercise among adolescents

Sensible physical exercise is shown to prevent certain neurovascular problems. However, in recent times, non-traumatic sudden death in young athletes has been observed and the incidence level is always very disturbing, because of the spontaneous nature of the occurrence. It most commonly occurs fivefold more in male than female athletes. Although it is believed that congenital cardiovascular disease is the leading cause of non-traumatic sudden athletic death, however, sudden physical alteration in the biochemical composition of the body system may, at least in part, play an important role. The role of antioxidants in the general maintenance of homeostasis has already been established. In this study, total antioxidant function in athletes subjected to controlled physical exercise was evaluated to determine the extent to which intensive physical exercise could alter the health conditions if adequate actions are not taken to adjust the biochemistry of the body system. Ten male field-track athletes were exercised using a fixed workload treadmill test. Blood samples were drawn before and after the exercise. The subjects exercised almost to their maximum running distance at a higher "fatigue" workload for a maximum of 20 min each day for five days. The lymphocytes' total antioxidant function was measured by addition of a peroxide (oxidative stress) to complete the medium. Lymphocyte growth response with peroxide was reported as a percentile of growth responses from a reference range of apparently healthy individuals. Values below the 25th percentile indicate a deficient antioxidant function. The results showed that although vitamin B3, B6, and B12 requirements were normal, there was a consistent low value in the total percentile of vitamins B1 (<79%), B2 (<54%), folate (<33%, and biotin (<70%). There was a dramatic decrease in the mean values of antioxidant function (38.1%) in all the subjects as opposed to the reference range of <75%. Overall reduction antioxidant function indicates decreased ability to resist oxidative stress, or an increased oxidant load, suggesting increased antioxidant utilization and/or cellular "tear and wear" scenario. It is therefore suggested that after intensive physical exercise, antioxidant functions should be monitored and supplemented whenever necessary to maintain the integrity of the cellular function.

Oxidant activity in skeletal muscle fibers is influenced by temperature, CO2 level, and muscle-derived nitric oxide

Free radicals are produced continuously by skeletal muscle fibers. Extracellular release of reactive oxygen species (ROS) and nitric oxide (NO) derivatives has been demonstrated, but little is known about intracellular oxidant regulation. We used a fluorescent oxidant probe, 2',7'-dichlorofluorescin (DCFH), to assess net oxidant activity in passive muscle fiber bundles isolated from mouse diaphragm and studied in vitro. We tested the following three hypotheses. 1) Net oxidant activity is decreased by muscle cooling. 2) CO(2) exposure depresses intracellular oxidant activity. 3) Muscle-derived ROS and NO both contribute to overall oxidant activity. Our results indicate that DCFH oxidation was diminished by cooling muscle fibers from 37 degrees C to 23 degrees C (P < 0.001). The rate of DCFH oxidation correlated positively with CO(2) exposure (0-10%; P < 0.05) and negatively with concurrent changes in pH (7.0-8.5; P < 0.05). Separate exposures to anti-ROS enzymes (superoxide dismutase, 1 kU/ml; catalase, 1 kU/ml), a glutathione peroxidase mimetic (ebselen, 30 microM), NO synthase inhibitors (N(omega)-nitro-l-arginine methyl ester, 1 mM; N(omega)-monomethyl-l-arginine, 1 mM), or an NO scavenger (hemoglobin, 1 microM) each inhibited DCFH oxidation (P < 0.05). Oxidation was increased by hydrogen peroxide, 100 microM, an NO donor (NOC-22, 400 microM), or the substrate for NO synthase (l-arginine, 5 mM). We conclude that net oxidant activity in resting muscle fibers is 1) decreased at subphysiological temperatures, 2) increased by CO(2) exposure, and 3) influenced by muscle-derived ROS and NO derivatives to similar degrees.

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

AIM

The purpose of this study was to determine the effects of both a short (12 weeks) and a long-term (24 weeks) endurance treadmill-training programme on the levels of oxidative stress markers, the activity of the enzymatic antioxidants, and the content of the 72 kDa heat shock protein (HSP72) in rat myocardium.

METHODS

Thirty male Wistar rats were randomly assigned to exercise trained (n = 16) and sedentary (n = 14) groups. After 12 week of training, eight rats were killed while the remaining eight continued the training programme until 24 week.

RESULTS

Seven sedentary controls were killed together with each trained group. Levels of thiobarbituric acid-reactive substances (TBARS), protein carbonyls, and total and oxidized glutathione (tGSH and GSSG) in myocardial homogenates were unchanged by training irrespective of the protocol duration. However, an increased content of the oxidative stress biomarkers was detected in hearts from both the 24-week trained rats and their sedentary controls when compared with their corresponding 12-week groups. The antioxidant enzymatic activities total and mitochondrial superoxide dismutase (tSOD and mtSOD, respectively), glutathione peroxidase (GPX) and glutathione reductase (GR), remained unchanged after the 12-week training period whereas a significant increase in tSOD and mtSOD activities (18%, P < 0.05) was observed in heart homogenates of 24-week trained animals as compared with their sedentary controls. HSP72 expression levels were not significantly modified after 12 week of training but a threefold increase was detected after 24 week (P < 0.05).

CONCLUSION

These results demonstrate that a long-term endurance training (24 weeks) induced discrete increases in antioxidant enzyme activities in rat myocardium and elicited a marked enhancement in HSP72 expression levels. However, a shorter training programme (12 weeks), was not effective in increasing heart antioxidant defences.

Loss of exercise-induced cardioprotection after cessation of exercise

Endurance exercise provides cardioprotection against ischemia-reperfusion (I/R) injury. Exercise-induced cardioprotection is associated with increases in cytoprotective proteins, including heat shock protein 72 (HSP72) and increases in antioxidant enzyme activity. On the basis of the reported half-life of these putative cardioprotective proteins, we hypothesized that exercise-induced cardioprotection against I/R injury would be lost within days after cessation of exercise. To test this, male rats (4 mo) were randomly assigned to one of five experimental groups: 1). sedentary control, 2). exercise followed by 1 day of rest, 3). exercise followed by 3 days of rest, 4). exercise followed by 9 days of rest, and 5). exercise followed by 18 days of rest. Exercise-induced increases (P < 0.05) in left ventricular catalase activity and HSP72 were evident at 1 and 3 days postexercise. However, at 9 days postexercise, myocardial HSP72 and catalase levels declined to sedentary control values. To evaluate cardioprotection during recovery from I/R, hearts were isolated, placed in working heart mode, and subjected to 20.5 min of global ischemia followed by 30 min of reperfusion. Compared with sedentary controls, exercised animals sustained less I/R injury as evidenced by maintenance of a higher (P < 0.05) percentage of preischemia cardiac work during reperfusion at 1, 3, and 9 days postexercise. The exercise-induced cardioprotection vanished by 18 days after exercise cessation. On the basis of the time course of the loss of cardioprotection and the return of HSP72 and catalase to preexercise levels, we conclude that HSP72 and catalase are not essential for exercise-induced protection during myocardial stunning. Therefore, other cytoprotective molecules are responsible for providing protection during I/R.

Relation between voluntary physical activity and oxidant/antioxidant status in rats

The relationship between voluntary distance running and antioxidant capacity was studied in rats after three weeks voluntary running. Hydroxyl radical level, reduced glutathione level, activities of glutathione reductase and superoxide dismutase were measured in plasma, liver, brain, soleus and gastrocnemius white muscle. Hydroxyl radical level of liver negatively correlated with the running distance (r=-0.616, P<0.001). The reduced glutathione levels of liver and brain increased depending on the running distance and the correlation was confirmed between them in liver (r=0.638, P<0.01) and brain (r=0.766, P<0.001). The hydroxyl radical level in liver positively correlated with the activities of glutathione reductase (r=0.464, P<0.05) and superoxide dismutase (r=0.549, P<0.05). A significant positive correlation was detected between the hydroxyl radical level and superoxide dismutase activity in brain (r=0.488, P<0.05). These results demonstrate that physical activity correlates well with glutathione level and anti-oxidant enzyme activities in liver, suggesting a close relation between physical activity and induction of antioxidant systems.

Reactive oxygen species in pregnant rats: effects of exercise and thermal stress

With the aim of evaluating the effect of interaction between physical training or exercise only during pregnancy and thermal stress on oxidative stress, and antioxidant mechanism sedentary pregnant rats (PS), exercised pregnant rats only during pregnancy (PE) and trained rats submitted to also exercise during pregnancy (PT) were compared (N=63). Exercise sessions consisted of swimming at 80% of maximal work load supported into water at 28 degrees C (hypothermia, PS 28, PE28, PT28) or 35 degrees C (thermal neutrality, PS35, PE35, PT35) or 39 degrees C (hyperthermia, PS39, PE39, PT39), for 30 min. The initial body weight in all groups of rats was from 177 to 207 g. On the 20th day of pregnancy, 24 h after the last immersion or swimming session venous blood was collected to determine oxidative stress. Plasma concentrations of means malondialdehyde (MDA) values measured as thiobarbituric acid reactive substances (TBARS); total glutathione (GSH) and vitamin E were determined. The oxidative stress index was calculated from the ratio TBARS/GSH and TBARS/Vitamin E. TBARS did not change on the group PE at different temperatures of water; TBARS were higher for PS28 than PS35 and PS39; PT35 had higher values than PT28 and PT39. For GSH, PS39 was lower than PS35; PE28 was higher than PE35 and PE39 and PT35 were lower than PT28 and PT39. Plasma concentration of vitamin E did not present any difference for sedentary rats at different water temperatures, but for PE28, the values were lower than for PE35 and PE39, whereas PT39 was lower than PT35 and PT28. In relation to TBARS/GSH, it was verified an increase in oxidative stress for PS28 (in relation to PS35 and PS39), PE35, and PT35 (in relation to PE28 and PE39 or PT28 and PT39); regarding the ratio TBARS/vitamin E, the highest values were obtained at 35 degrees C for PS and PT groups and at 39 for PE group. These results have shown the great complexity of the interaction between physical training, thermal stress and pregnancy. Apparently, hypothermia produces large index of oxidative stress only in sedentary rats, but this index was greater at 35 degrees C in relation to extreme temperatures for trained rats. These results have suggested that physical training allows a more efficient activation of antioxidant mechanisms under thermal stress.

Interrelationship of smoking, paraoxonase activity, and leisure time physical activity: a population-based study

METHODS: We determined the effect of smoking on PON1 activity levels in a population-based sample of 1380 subjects and examined the possibility of regular physical activity modulating the effect of cigarette smoking on PON1 activity levels at a population level. RESULTS: Mean PON1 activity was significantly lower in smokers than in non- or ex-smokers (237.6+/-8.4 vs. 276.7+/-5.3 U/l, mean+/-S.E.M.; P= 0.001). PON1 activity levels were significantly higher in physically active subjects than in those who were inactive (296.1+/-10.4 vs. 260.1+/-9.2 U/l; P=0.002). Inactive smokers showed significantly lower PON1 activity levels than inactive nonsmokers (P=0.002). These differences disappeared when active nonsmokers were compared with active smokers. Serum PON1 activity levels were found to be significantly increased in active smokers compared to those in inactive smokers. A statistically significant interaction (P=0.003) between smoking and physical activity on PON1 activity was observed. CONCLUSION: Smoking appears to have a deleterious effect on PON1 activity levels. Being physically active clearly attenuates this effect.

Effect of gender differences and voluntary exercise on antioxidant capacity in rats

The effects of gender difference and voluntary exercise on antioxidant capacity in rats were evaluated. The subjects were divided into two groups, physically active and sedentary. In the sedentary group, the level of hydroxyl radical in the liver was higher (P<0.001) in male rats than in female rats, however, in the physically active group, the level in male rats was lower (P<0.05) than in female rats. The levels of reduced glutathione (GSH) in physically active males and females were higher compared to those in the sedentary group. The physically active group also showed an increase in antioxidant enzymes, such as glutathione peroxidase (GPx), glutathione reductase (GR) and superoxide dismutase activities. The level of liver GSH was higher in physically active females than in physically active males. For both groups, GPx and GR activities in females were significantly higher than in males. These results indicate that female rats have an intrinsically higher antioxidant capacity, which resulted in increased levels of GSH via the glutathione redox cycle and gamma-glutamyl cycle enzymes. The adaptation to altered antioxidant capacity, induced by physical activity, appeared to be affected by gender differences.

Oxidative damage increases with age in a canine model of human brain aging

We assayed levels of lipid peroxidation, protein carbonyl formation, glutamine synthetase (GS) activity and both oxidized and reduced glutathione to study the link between oxidative damage, aging and beta-amyloid (Abeta) in the canine brain. The aged canine brain, a model of human brain aging, naturally develops extensive diffuse deposits of human-type Abeta. Abeta was measured in immunostained prefrontal cortex from 19 beagle dogs (4-15 years). Increased malondialdehyde (MDA), which indicates increased lipid peroxidation, was observed in the prefrontal cortex and serum but not in cerebrospinal fluid (CSF). Oxidative damage to proteins (carbonyl formation) also increased in brain. An age-dependent decline in GS activity, an enzyme vulnerable to oxidative damage, and in the level of glutathione (GSH) was observed in the prefrontal cortex. MDA level in serum correlated with MDA accumulation in the prefrontal cortex. Although 11/19 animals exhibited Abeta, the extent of deposition did not correlate with any of the oxidative damage measures, suggesting that each form of neuropathology accumulates in parallel with age. This evidence of widespread oxidative damage and Abeta deposition is further justification for using the canine model for studying human brain aging and neurodegenerative diseases.

Age-related changes in the distribution of nitrotyrosine in the cerebral cortex and hippocampus of rats

A wealth of indirect evidence implicates oxidative damage of cellular constituents in aging, as well as in the pathogenesis of the neurodegenerative diseases of later years. In the present study, we have determined age-related changes in the distribution of 3-nitrotyrosine (3-NT) in the cerebral cortex and hippocampus of rats. In adult rats, no 3-NT-immunoreactive cells were found in the cerebral cortex and hippocampus, whereas 3-NT immunoreactivity was significantly increased in aged rats. Some pyramidal cells of CA3 area and granule cells of the dentate gyrus highly expressed 3-NT in aged rats. Many interneurons located within stratum pyramidale and stratum oriens of CA1 were strongly immunoreactive for 3-NT. Our first demonstrations of increased 3-NT in the cerebral cortex and hippocampus during aging implicate these areas as sites for functionally significant oxidative damage. The mechanisms underlying the increased immunoreactivity for 3-NT, and the functional implications of this increase, require elucidation.

Detection of reactive oxygen and reactive nitrogen species in skeletal muscle

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are usually identified with pathological states and mediators of cellular injury. However, over the last decade ROS and RNS have been identified in skeletal muscle under physiological conditions. Detection of ROS and RNS production by skeletal muscle cells is fundamental to the problem of differentiating between physiological and pathological levels. The goal of this paper is to review the techniques that have been used to detect ROS and RNS in skeletal muscle. Electron spin resonance, fluorescent assays, cyotchrome c reduction, chemiluminescence, hydroxylation of salicylate, and nitration of phenylalanine are some of the assay systems that have been used thus far. A large body of evidence now indicates that ROS and RNS are continually produced by many different skeletal muscle types studied in vivo, in situ, and in vitro. Under resting conditions, ROS and RNS are detectable in both intracellular and extracellular compartments. Production increases during both non-fatiguing and fatiguing muscle contractions. In the absence of disease, the individual molecular species detected in skeletal muscle include parent radicals for the ROS and RNS cascades: superoxide anions and nitric oxide. Both are generated at rates estimated to range from pmol-to-nmol/mg muscle/minute. Evidence indicates that hydrogen peroxide, hydroxyl radicals, and peroxynitrite are also present under physiological conditions. However, the molecular species that mediate specific biological effects remains largely undetermined, as do the sources of ROS and RNS within muscle fibers. Eventual delineation of the mechanisms whereby ROS and RNS regulate cellular function will hinge on our understanding of the production and distribution of ROS and RNS within skeletal muscle.

Role of vitamin E and oxidative stress in exercise

Reactive oxygen species (ROS) play an important role as mediators of skeletal muscle damage and inflammation after strenuous exercise. These ROS arise largely from increases in mitochondrial oxygen consumption and electron transport flux. Bouts of intense exercise are associated with increases in lipid peroxidation, generating malondialdehyde and F(2alpha)-isoprostanes, and the release of muscle enzymes like lactate dehydrogenase and creatine kinase. Dietary and enzymatic antioxidant defenses appear to play a protective role in muscle cells by reducing associated oxidative damage to lipids, nucleic acids, and protein. However, studies of the use of dietary antioxidants like vitamin E to reduce exercise-induced muscle injury have met with mixed success. The equivocal nature of these results appear to reflect a diversity of factors including the antioxidant(s) tested, the nature and timing of the exercise, the age and fitness of the subjects, and the methodology for assessing oxidative stress.

Regular exercise improves cognitive function and decreases oxidative damage in rat brain

The biochemical mechanisms by which regular exercise significantly benefits health and well being, including improved cognitive function, are not well understood. Four-week-old (young) and 14-month-old (middle aged) Wistar rats were randomly assigned to young control and young exercised, middle-aged control and middle-aged exercised groups. Exercise groups were exposed to a swimming regime of 1 h a day, 5 days a week for 9 weeks. The passive avoidance test showed that middle-aged exercised rats had significantly (P<0.05) better short- (24 h) and long-term (72 h) memory than aged-matched control rats. Conditioned pole-jumping avoidance learning was improved markedly in both age groups by exercise. Brain thiobarbituric acid-reactive substances and 8-hydroxy-2'deoxyguanosine content in the DNA did not change significantly, while the protein carbonyl levels decreased significantly (P<0.05) in both exercised groups. This decrease was accompanied by an increase in the chymotrypsin-like activity of proteasome complex in the exercised groups, whereas trypsin-like activity did not differ significantly between all groups. The DT-diaphorase activity increased significantly (P<0.05) in the brain of young exercised animals. These data show that swimming training improves some cognitive functions in rats, with parallel attenuation of the accumulation of oxidatively damaged proteins.

The effects of chronic exercise on anesthesia induced hepatotoxicity

A hypoxic rat model of halothane-induced hepatotoxicity, which is known to produce liver damage, was used to determine the effects of chronic exercise on halothane-induced hepatotoxicity and on reduced hepatic glutathione (GSH) levels. Metabolism of volatile anesthetics may generate metabolites that can cause mild and transient hepatotoxicity.

METHODS

Six male Sprague-Dawley rats completed a 10-wk (5 d x wk(-1)) treadmill running protocol. Twelve age-matched animals were used as sedentary controls. After the completion of exercise training, rats were exposed for 2 h to 1% halothane in 14% O2. Twenty-four hours later, animals were anesthetized with sodium pentobarbital and sacrificed. Livers were excised, stained, and evaluated for hepatotoxicity using a histopathological 0 (normal) to 5 (severe damage) point categorical scale and for the determination of GSH levels.

RESULTS

Median histopathologic scores revealed significantly lower indications of hepatotoxicity in exercise animals as compared with control animals (score = 0.25 vs 1.50; P < 0.05). Liver damages scores between 1 and 5 were observed in 75% (9 of 12) of the control animals, whereas only 1 of 6 exercise animals had a score greater than 1 (P < 0.05). No significant difference was observed in reduced GSH levels.

CONCLUSIONS

Chronic exercise improves the detoxicant ability of the liver for halothane anesthesia as noted by the ameliorated liver damage and reduced incidence of halothane-induced hepatotoxicity in the exercise animals.

Physical exercise and antioxidant defenses in the heart

Cardiac muscle relies highly on aerobic metabolism. Heart muscle has a high oxygen uptake at resting conditions, which increases many fold during exhaustive physical exercise. Such a high rate of oxidative metabolism is often associated with enhanced production of reactive oxygen metabolites. A single bout of strenuous exercise has been demonstrated to induce oxidative damage in heart. Such oxidant insult may lead to adaptive responses and strengthen antioxidant defenses in the heart tissue. Endurance exercise training has indeed been shown to upregulate heart tissue antioxidant defenses. Recently, we have observed that even predominantly anaerobic sprint training regimens may enhance cardiac antioxidant defenses. Regular physical exercise may beneficially influence cardiac antioxidant defenses and promote overall cardiac function.

Basal and IL-1beta-stimulated cytokine and neuropeptide mRNA expression in brain regions of young and old Long-Evans rats

Young and old Long-Evans rats respond with fevers of equal magnitude and duration to the brain administration of interleukin-1beta (IL-1beta). Here, we characterized brain regional mRNA expression of cytokine and neuropeptide components in response to the brain administration of IL-1beta. We used specific and highly sensitive RNase protection assays to determine mRNA changes for IL-1beta, IL-1 receptor type I (IL-1RI), IL-1R accessory proteins I and II (IL-1R AcP I and II), IL-1 receptor antagonist (IL-1Ra), transforming growth factor-beta1 (TGF-beta1), glycoprotein 130 (gp 130), leptin receptor (OB-R), neuropeptide Y (NPY) and pro-opiomelanocortin (POMC) in the cerebellum, parieto-frontal cortex, hippocampus, hypothalamus, and midbrain of male young (3-5 months) and old (24-26 months) Long-Evans rats. In both young and old rats, IL-1beta induced a significant up-regulation of cerebellar IL-1Ra, IL-1RI, and TGF-beta1 mRNAs; hippocampal TGF-beta1 mRNA; hypothalamic IL-1beta, IL-1Ra, TGF-beta1, and gp 130 mRNAs; and midbrain IL-1beta and TGF-beta1 mRNAs. There were no age-related differences in any cytokine mRNA levels under basal or IL-1beta-stimulated conditions. Levels of hypothalamic POMC mRNA were different between age groups under basal and stimulated conditions. IL-1R AcP I and leptin receptor did not change in any brain region from either young or old rats, suggesting specificity of transcriptional changes. The data show that old Long-Evans rats are not defective in their capacity to develop an appropriate cytokine response to the brain administration of IL-1beta. The implications of these findings for neuroimmunological-neuroinflammatory and neurotoxic/neurodegenerative processes are discussed.

Myocardial and skeletal muscle aging and changes in oxidative stress in relationship to rigorous exercise training

Cardiac and skeletal muscle are very different functional tissues, and we would expect a variation in the ROS generation, in ageing and rigorous exercise-related in both tissues. We determined TBARS, total SOD, Cu, ZnSOD and MnSOD activities, and the patterns of SOD isoenzymes in skeletal muscle and heart of male Wistar rats, young and old, in rest and after rigorous exercise. There were no differences in the levels of lipoperoxidation in aged rest animals in both tissues, but the level was increased after exhaustion. The level of SOD activities was bigger in the heart than in skeletal muscle. Total SOD and Cu, ZnSOD activities were higher in old rest animals in the skeletal muscle than in young rest rats. This change did not occur in the heart. After rigorous exercise, the level of SOD activities was increased in young rats in both tissues. However, in old exhausted rats, the activities were only elevated in the heart. Different Cu, ZnSOD isoenzyme patterns showed in relation to tissues. In the skeletal muscle in old animals, the Cu, ZnSOD isoenzyme pattern was modified. The rigorous exercise did not change this pattern. The pattern of MnSOD isoenzyme was not varied in either tissue, age nor and exercise.

Effects of endurance physical training on hydroxyl radical generation in rat tissues

Physical exercise is known to increase oxygen consumption to compensate for enhanced ATP consumption and thus to induce oxidative stress in tissues. Our previous data indicate that training significantly increased the hydroxyl radical level in rat tissues after physical exercise, but reduced the basal level in aged rats. This result suggests the paradoxical effect of physical training, which may be to increase or scavenge reactive oxygen species (ROS) generated by physical exercise. In this paper, the effects of training on the levels of hydroxyl radicals and the anti-oxidative glutathione system, were examined in rats. After 3 weeks' training, rats were sacrificed at rest or after treadmill running, and the levels of hydroxyl radicals trapped with salicylic acid, reduced (GSH); and oxidized glutathione (GSSG) in tissues were quantified by high-performance liquid chromatography-electrochemical detection (HPLC-ECD). Endurance training reduced the basal level of hydroxyl radicals significantly in plasma and soleus muscle. In liver and brain a similar tendency was observed, but the difference was not statistically significant. In liver the basal level of GSH increased significantly after training. Slower training with longer duration reduced the basal levels of hydroxyl radical in plasma more markedly than more intense training. These results suggest that endurance exercise can increase the anti-oxidative capacity in rats.

Membrane and receptor modifications of oxidative stress vulnerability in aging. Nutritional considerations

Evidence suggests that oxidative stress (OS) may contribute to the pathogenesis of age-related decrements in neuronal function and that OS vulnerability increases as a function of age. In addition to decreased endogenous protection, increases in OS vulnerability may result from changes in membrane lipids and distribution of receptor subtype. Using a PC-12 cell model system, we have shown that H2O2 or dopamine (DA) exposure induced deficits in the cell's ability to clear (extrude/sequester, E/S) Ca2+ that are similar to those seen in aging. When plasma membrane concentrations of sphingomyelin (SPM) were used, the SPM metabolite, sphingosine-1-phosphate was increased to the same levels as those seen in aging, and enhancement of OS-induced decreases in calcium E/S following KCL depolarization was observed. Differential decreases in CA2+ E/S were also seen following DA-induced OS in COS-7 cells transfected with one of five muscarinic receptor subtypes. Cells transfected with either M1, M2, or M4 receptors showed significantly greater vulnerability to OS (as expressed by greater decrements in calcium E/S and cell death) than those transfected with M3 or M5 receptors. The vitamin E analogue, Trolox, and the nitrone-trapping agent, PBN, were not effective in altering E/S decrements but were effective in preventing cell death 24 h after OS exposure. These findings suggest that putative regional (e.g., striatum and hippocampus) increases in OS vulnerability and loss of neuronal function in aging may be dependent upon membrane SPM concentration and receptor subtype. In related studies, attempts were made to determine whether increased OS protection via nutritional increases in antioxidant levels in rats [using diets supplemented with vitamin E (500IU/kg), strawberry extracts (9.4 g/kg dried aqueous extract, DAE), spinach (6.7 g/kg DAE), or blueberry extracts (10 g/kg DEA for six weeks)] would protect against exposure to 100% O2 (a model of accelerated neuronal aging). Results indicated that these diets were effective in preventing OS-induced decrements in several parameters (e.g., nerve growth factor decreases), suggesting that although there may be increases in OS vulnerability in aging, phytochemicals present in antioxidant-rich foods may be beneficial in reducing or retarding the functional central nervous system deficits seen in aging or oxidative insult.

Long-term dietary strawberry, spinach, or vitamin E supplementation retards the onset of age-related neuronal signal-transduction and cognitive behavioral deficits

Recent research has indicated that increased vulnerability to oxidative stress may be the major factor involved in CNS functional declines in aging and age-related neurodegenerative diseases, and that antioxidants, e.g., vitamin E, may ameliorate or prevent these declines. Present studies examined whether long-term feeding of Fischer 344 rats, beginning when the rats were 6 months of age and continuing for 8 months, with diets supplemented with a fruit or vegetable extract identified as being high in antioxidant activity, could prevent the age-related induction of receptor-mediated signal transduction deficits that might have a behavioral component. Thus, the following parameters were examined: (1) oxotremorine-enhanced striatal dopamine release (OX-K+-ERDA), (2) cerebellar beta receptor augmentation of GABA responding, (3) striatal synaptosomal 45Ca2+ clearance, (4) carbachol-stimulated GTPase activity, and (5) Morris water maze performance. The rats were given control diets or those supplemented with strawberry extracts (SE), 9.5 gm/kg dried aqueous extract (DAE), spinach (SPN 6.4 gm/kg DAE), or vitamin E (500 IU/kg). Results indicated that SPN-fed rats demonstrated the greatest retardation of age-effects on all parameters except GTPase activity, on which SE had the greatest effect, whereas SE and vitamin E showed significant but equal protection against these age-induced deficits on the other parameters. For example, OX-K+-ERDA enhancement was four times greater in the SPN group than in controls. Thus, phytochemicals present in antioxidant-rich foods such as spinach may be beneficial in retarding functional age-related CNS and cognitive behavioral deficits and, perhaps, may have some benefit in neurodegenerative disease.

Exercise training reduces myocardial lipid peroxidation following short-term ischemia-reperfusion

PURPOSE

The purpose of these experiments was to test the hypothesis that endurance exercise training will reduce myocardial lipid peroxidation following short-term ischemia and reperfusion (I-R).

METHODS

Female Sprague-Dawley rats (4 months old) were randomly assigned to either a sedentary control group (N = 13) or to an exercise training group (N = 13). The exercise trained animals ran 4 d.wk-1 (90 min.d-1) at approximately 75% V02max. Following a 10-wk training program, animals were anesthetized, mechanically ventilated, and the chest was opened by thoracotomy. Coronary occlusion was achieved by a ligature around the left coronary artery; occlusion was maintained for 5 min followed by a 10-min period of reperfusion.

RESULTS

Although training did not alter (P > 0.05) myocardial activities of antioxidant enzymes (superoxide dismutase and glutathione peroxidase), training was associated with significant increase (P > 0.05) in heat shock protein (HSP72) in the left ventricle. Compared with controls, trained animals exhibited significantly lower levels (P < 0.05) of myocardial lipid peroxidation following I-R.

CONCLUSION

These data support the hypothesis that exercise training provides protection against myocardial lipid peroxidation induced by short-term I-R in vivo.