Oxidative stress during rehabilitation from protein malnutrition associated with aerobic exercise in rats

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

5-AMINOLEVULINIC ACID-INDUCED ALTERATIONS OF OXIDATIVE-METABOLISM IN SEDENTARY AND EXERCISE-TRAINED RATS

5-Aminolevulinic acid (ALA), a heme precursor that accumulates in acute intermittent porphyria patients and lead-exposed individuals, has previously been shown to autoxidize with generation of reactive oxygen species and to cause in vitro oxidative damage to rat liver mitochondria. We now demonstrate that chronically ALA-treated rats (40 mg/kg body wt every 2 days for 15 days) exhibit decreased mitochondrial enzymatic activities (superoxide dismutase, citrate synthase) in liver and soleus (type I, red) and gastrocnemius (type IIb, white) muscle fibers. Previous adaptation of rats to endurance exercise, indicated by augmented (cytosolic) CuZn-superoxide dismutase (SOD) and (mitochondrial) Mn-SOD activities in several organs, does not protect the animals against liver and soleus mitochondrial damage promoted by intraperitoneal injections of ALA. This is suggested by loss of citrate synthase and Mn-SOD activities and elevation of serum lactate levels, concomitant to decreased glycogen content in soleus and the red portion of gastrocnemius (type IIa) fibers of both sedentary and swimming-trained ALA-treated rats. In parallel, the type IIb gastrocnemius fibers, which are known to obtain energy mainly by glycolysis, do not undergo these biochemical changes. Consistently, ALA-treated rats under swimming training reach fatigue significantly earlier than the control group. These results indicate that ALA may be an important prooxidant in vivo.

Conventional (MG-BR46 Conquista) and Transgenic (BRS Valiosa RR) Soybeans Have No Mutagenic Effects and May Protect Against Induced-DNA Damage In Vivo

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Protective effect of safranine on the mitochondrial damage induced by Fe(II)citrate: Comparative study with trifluoperazine

In this study, we show that safranine at the concentrations usually employed as a probe of mitochondrial membrane potential significantly protects against the oxidative damage of mitochondria induced by Fe(II)citrate. The effect of safranine was illustrated by experiments showing that this dye strongly inhibits both production of thiobarbituric acid-reactive substances and membrane potential decrease when energized mitochondria were exposed to Fe(II)citrate in the presence of Ca 2+ ions. Similar results were obtained with the lipophylic compound trifluoperazine. It is proposed that, like trifluoperazine, safranine decreases the rate of lipid peroxidation due to its insertion in the membrane altering the physical state of the lipid phase.

Evaluation of a protein deficient diet in rats through blood oxidative stress biomarkers

Protein malnutrition leads to functional impairment in several organs, which is not fully restored with nutritional recovery. Little is known about the role of oxidative stress in the genesis of these alterations. This study was designed to assess the sensitivity of blood oxidative stress biomarkers to a dietary protein restriction. Male Wistar rats were divided into two groups, according to the diet fed from weaning (21 days) to 60 day old: normal protein (17% protein) and low protein (6% protein). Serum protein, albumin, free fatty acid and liver glycogen and lipids were evaluated to assess the nutritional status. Blood glutathione reductase (GR) and catalase (CAT) activities, plasma total sulfhydryl groups concentration (TSG) as well as plasma thiobarbituric acid reactive substances (TBARs) and reactive carbonyl derivatives (RCD) were measured as biomarkers of the antioxidant system and oxidative damage, respectively. The glucose metabolism in soleus muscle was also evaluated as an index of stress severity imposed to muscular mass by protein malnutrition. No difference was observed in muscle glucose metabolism or plasma RCD concentration between both groups. However, our results showed that the low protein group had higher plasma TBARs (62%) concentration and lower TSG (44%) concentration than control group, indicating increased reactive oxygen species production in low protein group. The enhancement of erythrocyte GR (29%) and CAT (28%) activities in this group also suggest an adaptation to the stress generated by the protein deficiency. Taken together, the results presented here show that the biomarkers used were able to reflect the oxidative stress level induced by this specific protein deficient diet.

Natural gaps associated with oxidative stress in Willisornis poecilinotus (Aves: Thamnophilidae) in a tropical forest

Os distúrbios naturais nas florestas tropicais contribuem para heterogeneidade do habitat, alterando os padrões de distribuição das aves. Estas alterações no ambiente elevam o metabolismo, promovendo distúrbios no balanço redox, e em consequência o estresse oxidativo. O objetivo deste estudo foi comparar a abundância de Willisornis poecilinotus entre clareiras e sub-bosque de dossel intacto associando-a a altura da vegetação na Floresta Nacional de Caxiuanã. A seguir, foi avaliado o estresse oxidativo e os fatores promotores de estresse foram determinados nos ambientes selecionados. Foram capturados 81 espécimes de W. poecilinotus. O número de capturas foi superior nas clareiras, quando comparado ao sub-bosque de dossel contínuo. Os espécimes capturados nas clareiras apresentaram índices de estresse oxidativo significativamente elevados. Foi observada correlação significativa entre os marcadores de estresse oxidativo nas clareiras. As variações do biomarcador de dano oxidativo e do estresse oxidativo foram explicadas somente pelo sítio de amostragem. Estes resultados sugerem que as clareiras são sítios de estímulos estressores para W. poecilinotus o que provavelmente resulta da maior demanda metabólica para novas estratégias de forrageio e para evitar a predação.

Oxidative stress on cardiotoxicity after treatment with single and multiple doses of doxorubicin

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

Dose-dependent effect of Resveratrol on bladder cancer cells: Chemoprevention and oxidative stress

Background: Over 6 million people die annually in the world because of cancer. Several groups are focused on studying cancer chemoprevention approaches. Resveratrol, a polyphenol, at high dosages, has been reported as antitumor and chemopreventive. However, it has a dose-dependent effect on cell death, even on some cancer cells. Objectives: Our aim was to investigate this dose-dependent effect on human bladder carcinoma ECV304 cells during oxidative stress condition. Methods: For this purpose. ECV304 cells incubated with different Resveratrol concentrations were analyzed as for their metabolic rate, membrane permeability, DNA fragmentation, anti/proapoptotic protein levels and phosphatidylserine exposure after oxidative stress. Results: Resveratrol induced cell death at high concentrations (>20 mu M), but not at low ones (0.1-20 mu M). Pretreatment with 2.5 mu M protected the cells from oxidative damage, whereas 50 mu M intensified the cell death and significantly increased Bad/Bcl-2 ratio (proapoptotic/antiapoptotic proteins). Resveratrol was able to modulate NO and PGE(2) secretion and performed an anti-adhesion activity of neutrophils on PMA-activated ECV304 cells. Conclusions: Resveratrol at high doses induces cell death of ECV304 cells whereas low doses induce protection. Modulation of Bcl-2 protein induced by Resveratrol could be mediating this effect. This information about the role of Resveratrol on cancer alerts us about its dose-dependent effects and could lead the design of future chemoprevention strategies. Published by Elsevier Ireland Ltd.

Dietary carotenoid lutein protects against DNA damage and alterations of the redox status induced by cisplatin in human derived HepG2 cells

Several epidemiological and experimental studies has been reported that lutein (LT) presents antioxidant properties. Aim of the present study was to investigate the protective effects of LT against oxidative stress and DNA damage induced by cisplatin (cDDP) in a human derived liver cell line (HepG2). Cell viability and DNA-damage was monitored by MU and comet assays. Moreover, different biochemical parameters related to redox status (glutathione, cytochrome-c and intracellular ROS) were also evaluated. A clear DNA-damage was seen with cDDP (1.0 mu M) treatment. In combination with the carotenoid, reduction of DNA damage was observed after pre- and simultaneous treatment of the cells, but not when the carotenoid was added to the cells after the exposure to cDDP. Exposure of the cells to cDDP also caused significant changes of all biochemical parameters and in co-treatment of the cells with LT, the carotenoid reverted these alterations. The results indicate that cDDP induces pronounced oxidative stress in HepG2 cells that is related to DNA damage and that the supplementation with the antioxidant LT may protect these adverse effects caused by the exposure of the cells to platinum compound, which can be a good predict for chemoprevention. (C) 2011 Elsevier Ltd. All rights reserved.

Hydroxyl scavenging activity accounts for differential antioxidant protection of Plantago major against oxidative toxicity in isolated rat liver mitochondria

Objectives The aim of this work was to study the effects of P. major against the oxidative damage of isolated rat liver mitochondria. Methods The extracts were obtained using methanol (MeOH), ethyl acetate (EAc), dichloromethane (DCM), and hexane (Hex) as solvents. Key findings Hex, DCM, and EAc totally, and MeOH partially, inhibited ROS generation and lipid peroxidation of membranes induced by Fe2+ or t-BOOH. However, only MeOH was able to prevent the t-BOOH-induced glutathione and NAD(P)H oxidation. All extracts chelated Fe2+ and reduced DPP Hradicals. EPR analysis revealed that P. major exhibited potent scavenger activity for hydroxyl radicals. Conclusions The potent antioxidant activity exhibited by P. major was able to prevent oxidative mitochondrial damage, contributing to the understanding of its hepatoprotective action against ROS-mediated toxicity.

Nitroxides attenuate carrageenan-induced inflammation in rat paws by reducing neutrophil infiltration and the resulting myeloperoxidase-mediated damage

Tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl) and other cyclic nitroxides have been shown to inhibit the chlorinating activity of myeloperoxidase (MPO) in vitro and in cells. To examine whether nitroxides inhibit MPO activity in vivo we selected acute carrageenan-induced inflammation on the rat paw as a model. Tempol and three more hydrophobic 4-substituted derivatives (4-azido, 4-benzene-Sulfonyl, and 4-(4-phenyl-1H-1,2,3-triazol-1-yl)) were synthesized, and their ability to inhibit the in vitro chlorinating activity of MPO and carrageenan-induced inflammation in rat paws was evaluated. All of the tested nitroxides inhibited the chlorinating activity of MPO in vitro with similar IC50 values (between 1.5 and 1.8 mu M). In vivo, the attenuation of carrageenan-induced inflammation showed some correlation with the lipophilicity of the nitroxide at early time points but the differences in the effects were small (< 2-fold) compared with the differences in lipophilicity (> 200-fold). No inhibition of MPO activity in vivo was evident because the levels of MPO activity in rat paws correlated with the levels of MPO protein'. Likewise, paw edema, levels of nitrated and oxidized proteins, and levels of plasma exudation correlated with the levels of MPO protein in the paws of the animals that were untreated or treated with the nitroxides. The effects of the nitroxides in vivo were compared with those of 4-aminobenzoic hydrazide and of colchicine. Taken together, the results indicate that nitroxides attenuate carrageenan-induced inflammation mainly by reducing neutrophil migration and the resulting MPO-mediated damage. Accordingly, tempol was shown to inhibit rat neutrophil migration in vitro. (C) 2012 Elsevier Inc. All rights reserved.

Low-level laser therapy (LLLT) in human progressive-intensity running: effects on exercise performance, skeletal muscle status, and oxidative stress

The aim of this work was to evaluate the effects of low-level laser therapy (LLLT) on exercise performance, oxidative stress, and muscle status in humans. A randomized double-blind placebo-controlled crossover trial was performed with 22 untrained male volunteers. LLLT (810 nm, 200 mW, 30 J in each site, 30 s of irradiation in each site) using a multi-diode cluster (with five spots - 6 J from each spot) at 12 sites of each lower limb (six in quadriceps, four in hamstrings, and two in gastrocnemius) was performed 5 min before a standardized progressive-intensity running protocol on a motor-drive treadmill until exhaustion. We analyzed exercise performance (VO(2 max), time to exhaustion, aerobic threshold and anaerobic threshold), levels of oxidative damage to lipids and proteins, the activities of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT), and the markers of muscle damage creatine kinase (CK) and lactate dehydrogenase (LDH). Compared to placebo, active LLLT significantly increased exercise performance (VO(2 max) p = 0.01; time to exhaustion, p = 0.04) without changing the aerobic and anaerobic thresholds. LLLT also decreased post-exercise lipid (p = 0.0001) and protein (p = 0.0230) damages, as well as the activities of SOD (p = 0.0034), CK (p = 0.0001) and LDH (p = 0.0001) enzymes. LLLT application was not able to modulate CAT activity. The use of LLLT before progressive-intensity running exercise increases exercise performance, decreases exercise-induced oxidative stress and muscle damage, suggesting that the modulation of the redox system by LLLT could be related to the delay in skeletal muscle fatigue observed after the use of LLLT.

Der enzymatische und anti-oxidative Mechanismus des anti-atherogenen Enzyms Paraoxonase-2

Das humane Enzym PON2 ist in eine Vielzahl pathophysiologischer Prozesse involviert und ist durch zwei Funktionen gekennzeichnet - eine enzymatische Laktonase-Aktivität und eine anti-oxidative Aktivität. Durch die Laktonase-Aktivität hydrolysiert PON2 vorwiegend das bakterielle Signalmolekül 3oxoC12. PON2 ist als Bestandteil des angeborenen Immunsystems anzusehen und trägt wahrscheinlich zur Immunabwehr gegen Infektionen mit den human-pathogenen Pseudomonas aeruginosa Bakterien bei. Durch die anti-oxidative Aktivität vermindert PON2 oxidative Schäden und verringert redox-abhängige pro-apoptotische Stimulation. Diese einzigartige Funktion von PON2 ist jedoch ambivalent zu betrachten, da hohe PON2-Spiegel zwar Arteriosklerose reduzieren können, aber im Verdacht stehen Tumorzellen zu stabilisieren.rnIn dieser Arbeit wurden die noch unbekannten Mechanismen und der Zusammenhang der enzymatischen und der anti-oxidativen Aktivität analysiert. In diesem Rahmen wurde gezeigt, dass PON2 spezifisch die Superoxidfreisetzung an Komplex I und III der Atmungskette in der inneren Mitochondrienmembran reduzieren kann. PON2 veränderte dabei weder die Aktivitäten der Superoxiddismutasen noch die Cytochrom C-Expression. Weiterhin konnte in dieser Arbeit erstmals gezeigt werden, dass PON2 O2- nicht direkt abbaut, sondern vielmehr dessen Bildung verhindert. Diese Erkenntnisse implizieren, dass PON2 die anti-oxidative Aktivität über eine Beeinflussung des Quinon-Pools vermittelt. Anhand von verschiedenen Punktmutationen konnte gezeigt werden, dass die Histidinreste-114 und -133 für die Laktonase-Aktivität essentiell sind. Weiterhin wurden die Glykosylierungsstellen von PON2 identifiziert und gezeigt, dass die Glykosylierung, nicht aber der natürliche Polymorphismus Ser/Cys311 für die Laktonase-Aktivität von Bedeutung ist. Von besonderer Bedeutung ist, dass keine dieser Mutationen die anti-oxidative Aktivität beeinflusste, wodurch erstmals die Unabhängigkeit der beiden Funktionen von PON2 gezeigt werden konnte. rnEs war bekannt, dass PON2 gegen intrinsische und ER-Stress-induzierte Apoptose schützt. Die Spezifität der anti-oxidativen / anti-apoptotischen Wirkung wurde hier an einem weiteren pathophysiologischen Modell untersucht. 7-Ketocholesterol (7-KC) ist der Hauptbestandteil des pro-arteriosklerotischen oxLDL und verursacht in Zellen des Gefäßsystems ER-Stress, oxidativen Stress und Apoptose. Unerwarteterweise konnte PON2 Endothelzellen nicht gegen den 7-KC-induzierten Zelltod schützen. Mehrere unabhängige experimentelle Ansätze belegen, dass 7-KC in Endothelzellen im Gegensatz zu Gefäßmuskelzellen den Zelltod über Autophagie und nicht über ER-Stress oder intrinsische Apoptose bewirkt. Weiterhin führt 7-KC, wie auch 3oxoC12 und Thapsigargin zu einem Abbau der PON2-mRNA, die über die 5’UTR der PON2-mRNA vermittelt wird. Diese Arbeit vermittelt detaillierte mechanistische Einsichten in die Funktionen von PON2, die für ihre Rolle bei Arteriosklerose, in der körpereigenen Immunabwehr und bei Krebs entscheidend sind.rn

In vivo and in vitro effects of antioxidant compounds and PPAR γ modulators on rainbow trout oxidative stress and lipid metabolism.

The aquafeed use of raw plant materials, as protein and lipid sources, has been considered and approved as a sustainable alternative to fish products (fish meal and oils) because the current trend to use high-lipid diets has been shown to induce undesirable increase in fat depots or further physiological alterations, such as induction of oxidative stress. In the aquaculture perspective, the addition of natural substances with antioxidant properties is an emerging strategy for protecting biological systems and foodstuffs from oxidative damage. Among natural substances, hydroxytyrosol (HT) and caffeic acid (CA) have attracted considerable attention as food antioxidant additives and modulators of physiological and molecular pathways involved in energy metabolism and adiposity. The aim of this study was to evaluate the effects of CA and HT on lipid metabolism and oxidative stress of rainbow trout (Oncorhynchus mykiss). In vitro results showed the potential anti-obesogenic effects of the compounds CA and HT on the adipose tissue of the rainbow trout. To support these data, in vitro assays performed (MTT, ORO, immunofluorescence) resulted in accordance among them; only results from proliferating cell nuclear antigen (PCNA) assay were not significant. In vivo results showed a possible anti-obesogenic effect of CA in liver and HT in adipose tissue. Regarding oxidative stress, we could hypothesize a possible anti-oxidant role of CA in liver.

Vitamin C deficiency in weanling guinea pigs: differential expression of oxidative stress and DNA repair in liver and brain

Neonates are particularly susceptible to malnutrition due to their limited reserves of micronutrients and their rapid growth. In the present study, we examined the effect of vitamin C deficiency on markers of oxidative stress in plasma, liver and brain of weanling guinea pigs. Vitamin C deficiency caused rapid and significant depletion of ascorbate (P < 0.001), tocopherols (P < 0.001) and glutathione (P < 0.001), and a decrease in superoxide dismutase activity (P = 0.005) in the liver, while protein oxidation was significantly increased (P = 0.011). No changes in lipid oxidation or oxidatively damaged DNA were observed in this tissue. In the brain, the pattern was markedly different. Of the measured antioxidants, only ascorbate was significantly depleted (P < 0.001), but in contrast to the liver, ascorbate oxidation (P = 0.034), lipid oxidation (P < 0.001), DNA oxidation (P = 0.13) and DNA incision repair (P = 0.014) were all increased, while protein oxidation decreased (P = 0.003). The results show that the selective preservation of brain ascorbate and induction of DNA repair in vitamin C-deficient weanling guinea pigs is not sufficient to prevent oxidative damage. Vitamin C deficiency may therefore be particularly adverse during the neonatal period.