Update on thiol status and supplements in physical exercise

C60 fullerene attenuates muscle force reduction in a rat during fatigue development

C₆₀ fullerene (C₆₀) as a nanocarbon particle, compatible with biological structures, capable of penetrating through cell membranes and effectively scavenging free radicals, is widely used in biomedicine. A protective effect of C₆₀ on the biomechanics of fast (m. gastrocnemius) and slow (m. soleus) muscle contraction in rats and the pro- and antioxidant balance of muscle tissue during the development of muscle fatigue was studied compared to the same effect of the known antioxidant N-acetylcysteine (NAC). C₆₀ and NAC were administered intraperitoneally at doses of 1 and 150 mg kg^-1, respectively, daily for 5 days and 1 h before the start of the experiment. The following quantitative markers of muscle fatigue were used: the force of muscle contraction, the level of accumulation of secondary products of lipid peroxidation (TBARS) and the oxygen metabolite H₂O₂, the activity of first-line antioxidant defense enzymes (superoxide dismutase (SOD) and catalase (CAT)), and the condition of the glutathione system (reduced glutathione (GSH) content and the activity of the glutathione peroxidase (GP_x) enzyme). The analysis of the muscle contraction force dynamics in rats against the background of induced muscle fatigue showed, that the effect of C₆₀, 1 h after drug administration, was (15-17)% more effective on fast muscles than on slow muscles. A further slight increase in the effect of C₆₀ was revealed after 2 h of drug injection, (7-9)% in the case of m. gastrocnemius and (5-6)% in the case of m. soleus. An increase in the effect of using C₆₀ occurred within 4 days (the difference between 4 and 5 days did not exceed (3-5)%) and exceeded the effect of NAC by (32-34)%. The analysis of biochemical parameters in rat muscle tissues showed that long-term application of C₆₀ contributed to their decrease by (10-30)% and (5-20)% in fast and slow muscles, respectively, on the 5th day of the experiment. At the same time, the protective effect of C₆₀ was higher compared to NAC by (28-44)%. The obtained results indicate the prospect of using C₆₀ as a potential protective nano agent to improve the efficiency of skeletal muscle function by modifying the reactive oxygen species-dependent mechanisms that play an important role in the processes of muscle fatigue development.

Effects of heat stimulation and l-ascorbic acid 2-phosphate supplementation on myogenic differentiation of artificial skeletal muscle tissue constructs

Although skeletal muscle tissue engineering has been extensively studied, the physical forces produced by tissue-engineered skeletal muscles remain to be improved for potential clinical utility. In this study, we examined the effects of mild heat stimulation and supplementation of a l-ascorbic acid derivative, l-ascorbic acid 2-phosphate (AscP), on myoblast differentiation and physical force generation of tissue-engineered skeletal muscles. Compared with control cultures at 37°C, mouse C2C12 myoblast cells cultured at 39°C enhanced myotube diameter (skeletal muscle hypertrophy), whereas mild heat stimulation did not promote myotube formation (differentiation rate). Conversely, AscP supplementation resulted in an increased differentiation rate but did not induce skeletal muscle hypertrophy. Following combined treatment with mild heat stimulation and AscP supplementation, both skeletal muscle hypertrophy and differentiation rate were enhanced. Moreover, the active tension produced by the tissue-engineered skeletal muscles was improved following combined treatment. These findings indicate that tissue culture using mild heat stimulation and AscP supplementation is a promising approach to enhance the function of tissue-engineered skeletal muscles. Copyright © 2015 John Wiley & Sons, Ltd.

Prepubertal children with suitable fitness and physical activity present reduced risk of oxidative stress

To assess the impact of fitness status and physical activity on oxidative stress in prepubertal children, we measured selected biomarkers such as protein carbonyls (PC), lipid peroxidation products, and total nitrites, as well as the antioxidant system: total glutathione (TG), oxidized glutathione (GSSG), reduced glutathione (GSH), superoxide dismutase activity, and glutathione peroxidase. A total of 132 healthy children ages 7-12, at prepubertal stage, were classified into two groups according to their fitness level: low fitness (LF) and high fitness (HF). They were observed while engaged in an after-school exercise program, and a questionnaire was created to obtain information on their physical activity or sedentary habits. Plasma and red blood cells were obtained to analyze biomarkers. Regarding oxidative stress markers, the LF group and the sedentary group showed higher levels of TG and GSSG and a lower GSH/GSSG ratio than the HF group and the children engaged in physical activity. A negative association was found between PC and GSSG and TG and between TG and the GSH/GSSG ratio. Moreover, a negative correlation was found between GSSG and fitness, with a positive correlation with the GSH/GSSG ratio. TG, GSSG, and the GSH/GSSG ratio seem to be reliable markers of oxidative stress in healthy prepubertal children with low fitness or sedentary habits. This research contributes to the recognition that an adequate level of fitness and recreational physical activity in childhood leads to better health and oxidative status.

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.

Effect of exercise on oxidative stress biomarkers

Acute bouts of aerobic and anaerobic exercise can induce a state of oxidative stress, as indicated by an increase in oxidized molecules in a variety of tissues and body fluids. The extent of oxidation is dependent on the exercise mode, intensity, and duration, and is specifically related to the degree of oxidant production. Findings of increased oxidative stress have been reported for both healthy and diseased subjects following single bouts of exercise. While acute exercise has the ability to induce an oxidative stress, this same exercise stimulus appears necessary to allow for an upregulation in endogenous antioxidant defenses. This chapter presents a summary of exercise-induced oxidative stress.

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.

Redox regulation of vitamin C transporter SVCT2 in C2C12 myotubes

We have previously demonstrated that skeletal muscle cells possess efficient systems for vitamin C accumulation; in particular, the SVCT2 transporter for ascorbic acid uptake seems to play a crucial role. In this study, we investigated the regulatory mechanism(s) accounting for SVCT2 activity in C2C12 myotubes. We found that transcription of the SVCT2 gene could be positively or negatively modulated by the presence of oxidant (H(2)O(2)) or antioxidant (lipoate) compounds, respectively. This redox-mediated regulation of SVCT2 expression seemed to be achieved via AP-1 and NF-kappaB signaling. Our findings could be relevant in skeletal muscle, where reactive oxygen species, naturally produced during physical exercise, can induce muscle damage. Thus, the redox-sensitive SVCT2 expression can be placed among the adaptive responses induced by contractile activity.

Effect of soy- and whey protein-isolate supplemented diet on the redox parameters of trained mice

BACKGROUND

A number of clinical trials have successfully been performed using whey and/or soy proteins in the treatment of many diseases. They both have antioxidant properties, which appears to be a factor in aerobic physical performance as well. In addition, these are the most often used supplements that sportsmen take to increase their performance.

AIM OF THE STUDY

To investigate the effect of whey and soy protein supplementation on redox parameters in the muscle, on body weight, and body composition in swimming-trained and non-trained animals.

METHODS

The effect of whey and soy protein-isolate supplementation on muscle redox parameters, body weight, and body composition in trained and non-trained mice was investigated after a single exhaustive bout of exercise. Steady state free radical concentration measured using electron spin resonance (ESR) spectroscopy, reduced and oxidized glutathione ratio, thiobarbituric acid-reactive substances (TBARS), and protein carbonyl levels of the red leg muscle were measured.

RESULTS

Free radical concentrations and glutathione composition of the tissue indicated that whey protein supplementation of the regular diet was able to prevent oxidative stress regardless of training. Soy protein supplementation decreased TBARS only in the muscle of untrained animals, while training per se lowered protein damage in all investigated groups. A mixture of soy and whey protein supplementation resulted in leaner animals after training, but had no synergistic effect on either of the measured redox parameters.

CONCLUSIONS

Athletes consuming these supplements could train with higher exercise intensity. The antioxidant effect of the two proteins is based on different mechanisms of action.

Analytical aspects of oxidatively modified substances in sports and exercises

Despite the health-promoting effects of physical activity, exercise enhances the formation of free radicals and other reactive species in animals and humans. Numerous techniques have been established to investigate the diverse modifications of biomolecules by oxidative stress. These analytical procedures include different methods, ranging from simple photometric assays to a combination of chromatographic methods with mass spectrometry. We summarize briefly those analytical techniques of oxidative damage to biomolecules that have been applied to the investigation of oxidative stress during exercise.

Anaerobic Exercise and Oxidative Stress: A Review

Oxidative stress and subsequent damage to cellular proteins, lipids, and nucleic acids, as well as changes to the glutathione system, are well documented in response to aerobic exercise. However, far less information is available on anaerobic exercise-induced oxidative modifications. Recent evidence indicates that high intensity anaerobic work does result in oxidative modification to the above-mentioned macromolecules in both skeletal muscle and blood. Also, it appears that chronic anaerobic exercise training can induce adaptations that act to attenuate the exercise-induced oxidative stress. These may be specific to increased antioxidant defenses and/or may act to reduce the generation of pro-oxidants during and after exercise. However, a wide variety of exercise protocols and assay procedures have been used to study oxidative stress pertaining to anaerobic work. Therefore, precise conclusions about the exact extent and location of oxidative macromolecule damage, in addition to the adaptations resulting from chronic anaerobic exercise training, are difficult to indicate. This manuscript provides a review of anaerobic exercise and oxidative stress, presenting both the acute effects of a single exercise bout and the potential for adaptations resulting from chronic anaerobic training. Key words: antioxidants, free radicals, training, lipid peroxidation, protein carbonyls

Acute and severe hypobaric hypoxia-induced muscle oxidative stress in mice: the role of glutathione against oxidative damage

This study intended to analyze: (1) the effects of acute and severe hypoxia exposure on skeletal muscle oxidative stress and oxidative damage markers; (2) the protective role of the antioxidant glutathione against oxidative damage; and (3) the expression of heat shock protein 70 kDa (HSP70) induced by this hypoxic insult. Forty mice were divided into four groups: control + placebo (C+P), hypoxia + placebo (H+P), control + l-buthionine-[ S, R]-sulfoximine (BSO, a GSH-depleting compound) (C+BSO) and hypoxia + BSO (H+BSO). Hypoxia groups were continuously exposed for 24 h to a hypobaric hypoxic environment equivalent to an altitude of 7000 m and sacrificed immediately after. Control groups were maintained at sea level during the experimental protocol. Analyzed biochemical parameters were: reduced (GSH) and oxidized (GSSG) glutathione, thiobarbituric acid reactive substances (TBARS), sulfhydryl protein groups (SH), N-acetyl-beta- d-glucosaminidase (NAG) and HSP70 protein. Hypoxia (H+P) per se, compared to C+P, induced a significant increase in %GSSG (5.68 vs. 1.14%), TBARS (436.7 vs. 227.9 nM), NAG (4.49 vs. 3.35 U/mg) and HSP70 (178.7 vs. 100%). Compared with H+P, H+BSO showed a significant decrease in total glutathione (19.30 vs. 6.13 nmol/mg) and an additional increase in %GSSG (5.68 vs. 11.33%) and in HSP70 expression (178.7 vs. 202.2%). However, no further oxidative damage was observed in H+BSO. These data suggest that acute hypoxia per se might enhance oxidative stress; however, the glutathione system seems to have a modest role in skeletal muscle protection against hypoxia-induced oxidative stress. Moreover, hypoxia and BSO treatment is a sufficient stimulus to promote HSP70 overexpression.