Exercise and oxidative stress: p,otential effects of antioxidant dietary strategies in sports

Free radicals are produced during aerobic cellular metabolism and have key roles as regulatory mediators in signaling processes. Oxidative stress reflects an imbalance between production of reactive oxygen species and an adequate antioxidant defense. This adverse condition may lead to cellular and tissue damage of components, and is involved in different physiopathological states, including aging, exercise, inflammatory, cardiovascular and neurodegenerative diseases, and cancer. In particular, the relationship between exercise and oxidative stress is extremely complex, depending on the mode, intensity, and duration of exercise. Regular moderate training appears beneficial for oxidative stress and health. Conversely, acute exercise leads to increased oxidative stress, although this same stimulus is necessary to allow an up-regulation in endogenous antioxidant defenses (hormesis). Supporting endogenous defenses with additional oral antioxidant supplementation may represent a suitable noninvasive tool for preventing or reducing oxidative stress during training. However, excess of exogenous antioxidants may have detrimental effects on health and performance. Whole foods, rather than capsules, contain antioxidants in natural ratios and proportions, which may act in synergy to optimize the antioxidant effect. Thus, an adequate intake of vitamins and minerals through a varied and balanced diet remains the best approach to maintain an optimal antioxidant status. Antioxidant supplementation may be warranted in particular conditions, when athletes are exposed to high oxidative stress or fail to meet dietary antioxidant requirements. Aim of this review is to discuss the evidence on the relationship between exercise and oxidative stress, and the potential effects of dietary strategies in athletes. The differences between diet and exogenous supplementation as well as available tools to estimate effectiveness of antioxidant intake are also reported. Finally, we advocate the need to adopt an individualized diet for each athlete performing a specific sport or in a specific period of training, clinically supervised with inclusion of blood analysis and physiological tests, in a comprehensive nutritional assessment. (C) 2015 Elsevier Inc. All rights reserved.

Effect of melatonin intake on oxidative stress biomarkers in male reproductive organs of rats under experimental diabetes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Tropical soils with high aluminum concentrations cause oxidative stress in two tomato genotypes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Low intensity physical exercise attenuates cardiac remodeling and myocardial oxidative stress and dysfunction in diabetic rats

We evaluated the effects of a low intensity aerobic exercise protocol on cardiac remodeling and myocardial function in diabetic rats. Wistar rats were assigned into four groups: sedentary control (C-Sed), exercised control (C-Ex), sedentary diabetes (DM-Sed), and exercised diabetes (DM-Ex). Diabetes was induced by intraperitoneal injection of streptozotocin. Rats exercised for 9 weeks in treadmill at 11 m/min, 18 min/day. Myocardial function was evaluated in left ventricular (LV) papillary muscles and oxidative stress in LV tissue. Statistical analysis was given by ANOVA or Kruskal-Wallis. Echocardiogram showed diabetic groups with higher LV diastolic diameter-to-body weight ratio and lower posterior wall shortening velocity than controls. Left atrium diameter was lower in DM-Ex than DM-Sed (C-Sed: 5.73 ± 0.49; C-Ex: 5.67 ± 0.53; DM-Sed: 6.41 ± 0.54; DM-Ex: 5.81 ± 0.50 mm; P < 0.05 DM-Sed vs C-Sed and DM-Ex). Papillary muscle function was depressed in DM-Sed compared to C-Sed. Exercise attenuated this change in DM-Ex. Lipid hydroperoxide concentration was higher in DM-Sed than C-Sed and DM-Ex. Catalase and superoxide dismutase activities were lower in diabetics than controls and higher in DM-Ex than DM-Sed. Glutathione peroxidase activity was lower in DM-Sed than C-Sed and DM-Ex. Conclusion. Low intensity exercise attenuates left atrium dilation and myocardial oxidative stress and dysfunction in type 1 diabetic rats.

The oxidation of p-phenylenediamine, an ingredient used for permanent hair dyeing purposes, leads to the formation of hydroxyl radicals: oxidative stress and DNA damage in human immortalized keratinocytes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The immune system is limited by oxidative stress: dietary selenium promotes optimal antioxidative status and greatest immune defense in pacu Piaractus mesopotamicus

Reactive oxygen species (ROS) are reactive molecules containing oxygen, that form as byproducts of aerobic metabolism, including immune system processes. Too much ROS may cause oxidative stress. In this study, we examined whether it can also limit the production of immune system compounds. To assess the relationship between antioxidant status and immunity we evaluated the effect of dietary supplementation with organic selenium, given at various levels for 10 days, on the antioxidant and immune system of the pacu fish (Piaractus mesopotamicus). Fish fed a diet containing 0.6 mg Se-yeast kg(-1) showed significant improvement in antioxidant status, as well as in hematological and immunological profiles. Specifically, they had the highest counts for catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), red blood cells, and thrombocytes; the highest leukocyte count (particularly for monocytes); and the highest serum lysozyme activity. There was also a positive correlation between GPx and lysozyme in this group of fish. These findings indicate that short-term supplementation with 0.6 mg Se-yeast kg(-1) reestablished the antioxidative status, allowing the production of innate components which can boost immunity without the risk of oxidative stress. This study shows a relationship between oxidative stress and immunity, and, from a practical perspective, shows that improving immunity and health in pacu through the administration of selenium could improve their growth performance.

Changes in the oxidative stress biomarkers in liver of streptozotocin-diabetic rats treated with combretum lanceolatum flowers extract

Aims: The study investigated the in vivo antioxidant activity and the in vitro radical scavenging capacity of the Combretum lanceolatum Pohl (Combretaceae) flowers ethanolic extract (ClEtOH) in streptozotocin-diabetic rats. Place and Duration of Study: Department of Chemistry, Federal University of Mato Grosso, Cuiabá, Brazil; between February 2012 and December 2012. Methodology: Male Wistar rats were divided into four groups: Normal rats treated with water/vehicle (N); diabetic rats treated with water (DC); diabetic rats treated with 250 mg/kg (DT250) or with 500mg/kg (DT500) of ClEtOH. After 21 days of treatment, liver samples were used for the analysis of the oxidative stress biomarkers and activity of antioxidant enzymes. In vitro radical scavenger capacity was investigated by the following methods: DPPH radical scavenging, ABTS radical cation decolorization and crocin bleaching assays. Results: Significant oxidative stress was observed in liver of DC, since the malondialdehyde (MDA, biomarker of lipoperoxidation) levels were increased in comparison with N. Increased activities of the antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were also observed in DC, which could represent a compensatory mechanism against oxidative stress. Glutathione (GSH) levels were lower and similar between N and DC. The MDA levels were significantly decreased in liver of rats from DT250 and DT500, reaching levels similar those of N, suggesting that ClEtOH prevented lipoperoxidation. The treatment of diabetic rats with ClEtOH also increased the GSH levels, as well as increased the GSH-Px activity, and did not change the SOD activity. The results of in vitro radical scavenging capacity indicated that ClEtOH is highly active. Conclusion: These findings indicate that ClEtOH has antioxidant properties in liver of diabetic rats, decreasing lipoperoxidation and increasing the endogenous antioxidant responses. Both the antihyperglycemic effect and the capacity to scavenge free radicals may be related to the antioxidant activity of ClEtOH in diabetes.

Understanding the influence of oxidative stress and physical exercise in the relationship between blood pressure and uric acid

Due to the high incidence and prevalence of hypertension, especially in the elderly population, several studies have been developed to understand the relationship between etiological factors and blood pressure control. It has been demonstrated that hypertensive patients tend to present a status of hyperuricemia. This result suggested that there is a relationship between blood pressure and uric acid concentrations. However there is still a lack of studies that focus on this relationship, and especially how physical exercise could affect the relationship between both of them. Thus, the purpose of this study is to review and discuss the relationship between hypertension and uric acid concentration pointing the oxidative stress as the main factor of this relationship and discuss the physical exercise as the main preventive factor of high uric acid concentrations and oxidative stress. It has been described an increase in oxidative stress during the uric acid pathway because the high production of anions superoxide. This in turn, increases the activation of renin-angiotensin system and decreases nitric oxide bioavailability which will compromise the vasodilatation mechanism. However physical exercises have been associated with improvements in antioxidant capacity and nitric oxide production and bioavailability which will improve the blood pressure control.

The role of oxidative stress in renal injury related to obesity

The mechanisms linking obesity to kidney damage are unknown. AGEs are responsible for renal damage in obese individuals. The receptor AGEs (RAGE) contributes to nuclear transcription factors that result in the production of proinflammatory cytokines and this seems to contribute to the development of renal disease. Thus, intervention with antioxidant can have an important effect in the prevention and treatment of pro-oxidant and pro-inflammatory state in the kidneys resulting from obesity.

cDNA representational difference analysis used in the identification of genes expressed by Trichophyton rubrum during contact with keratin

Dermatophytes are adapted to infect skin, hair and nails by their ability to utilize keratin as a nutrient source. Trichophyton rubrum is an anthropophilic fungus, causing up to 90% of chronic cases of dermatophytosis. The understanding of the complex interactions between the fungus and its host should include the identification of genes expressed during infection. To identify the genes involved in the infection process, representational difference analysis (RDA) was applied to two cDNA populations from T. rubrum, one transcribed from the RNA of fungus cultured in the presence of keratin and the other from RNA generated during fungal growth in minimal medium. The analysis identified differentially expressed transcripts. Genes related to signal transduction, membrane protein, oxidative stress response, and some putative virulence factors were up-regulated during the contact of the fungus with keratin. The expression patterns of these genes were also verified by real-time PCR, in conidia of T. rubrum infecting primarily cultured human keratinocytes in vitro, revealing their potential role in the infective process. A better understanding of this interaction will contribute significantly to our knowledge of the process of dermatophyte infection.

An Arabidopsis Mitochondrial Uncoupling Protein Confers Tolerance to Drought and Salt Stress in Transgenic Tobacco Plants

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Does low-protein diet improve broiler performance under heat stress conditions?

Nutrition for broilers under high temperatures is extremely important for brazilian broiler chicken industry because the amounts of consumed nutrients and environmental temperature have great effects on bird performance and carcass quality. Among diet nutrients, protein has the highest heat increment; thus, during many years, diets with low protein level were recommended in order to reduce heat production in broiler chickens under heat stress. However, reports have shown that low-protein diets have negative effects on broiler performance when environmental temperature is high, because during heat stress, low food intake associated to a low diet protein induce amino acid deficiencies. Other studies have shown that broilers fed low-protein diets increase their energy requirement for maintenance with higher heat production. Thus, with the growth of broiler industry in tropical areas more challenges need to be faced by the farmers. So, both the ambient and nutritional conditions ought to be well managed to avoid negative effects on poultry production once they can affect the metabolism (body heat production under low temperature and body heat dissipation under high temperature) with consequence on poultry performance (meat and eggs).

Brain and hepatic Hsp70 protein levels in heat-acclimated broiler chickens during heat stress

In the present study we have investigated the effects of heat acclimation on brain and hepatic Hsp70 protein levels and body temperature of broiler chickens in response to gradual heat stress. Two groups of broilers were raised up to 47 days of age under distinct temperature conditions: thermoneutral (TN, according to bird age) or hot environmental (HS, 31-33°C). At 46 days of age, the birds reared at high ambient temperature were transferred to thermoneutrality conditions. After 18 h, these birds and the birds reared at thermoneutral temperature were submitted to gradual heat stress in a climatic chamber so that environment temperature was increased from 28 to 40ºC at a rate of 2ºC/h. Colonic temperature was measured using a thermometer sensor probe at each two hours, and hepatic and brain tissues were collected immediately after slaughter in order to assess Hsp70 protein level by Western blotting analysis. The colonic temperatures of birds reared at high temperature increased steeply during the first 2 h of heat stress (1.06ºC/h) and more slowly thereafter (0.59ºC/h). Broilers reared at thermoneutral temperature showed a small increase in the first 4 h of heat stress (0.18ºC/h) and then colonic temperature increased sharply (0.72ºC/h). Nevertheless, both groups presented similar final colonic temperature by the end of the stress period. Hsp70 levels (ng Hsp70 µg total protein-1) did not change in the liver or brain of the birds reared at high temperature. on the other hand, both liver and brain Hsp70 levels increased significantly during heat stress in the animals reared at thermoneutrality, with a higher expression of this peptide in brain tissue.