Does hydrostatic pressure have an effect on reactive oxygen species in the eel?

Eels are submitted to hydrostatic pressure (HP) during their spawning migration (about 6000 Km). Before migration, they change from the yellow to the silver stage (silvering process). The effects of HP in relation to the silvering process have been studied on aerobic metabolism and more precisely on reactive oxygen species (ROS) metabolism. HP acclimatization of yellow eels improves oxidative phosphorylation together with supposed concomitant changes in electron leak and ROS production. Therefore hydroxyl radical (OH*) production, superoxyde dismutase and catalase activities, malondialdehyde content and in parallel oxygen consumption were measured in the red muscle of long-term pressure exposed and control group yellow and silver eels. At atmospheric pressure, yellow eels exhibited significantly higher oxygen consumption and OH* production than silver eels; and significantly lower malondialdehyde content. This could be due to the increase in membrane fluidity induced by the silvering process. Long-term HP exposure decreases yellow eel oxygen consumption which becomes similar to that of the silver stage. In parallel there is a decrease in OH* production and concomitantly antioxidant enzyme activities follow the same tendency. Thus the respiratory chain improvement in pressure acclimatized yellow eels is accompanied by a ROS production decrease which could mean an electron leak decrease.     

Exercise as an antioxidant: it up-regulates important enzymes for cell adaptations to exercise

Aims. – To assess the role of the reactive oxygen species (ROS) in cell signalling and in the regulation of gene expression.Methods. – Exercise causes oxidative stress only when exhaustive. Strenuous exercise causes oxidation of glutathione, release of cytosolic enzymes, and other signs of cell damage. We have tested this hypothesis by studying the effect of inhibition of ROS production by allopurinol (an inhibitor of xanthine oxidase, a free radical generating enzyme) on cell signalling pathways in marathon runners and in rats submitted to exhaustive exercise by running on a treadmill.Results. – Exercise caused an activation of NF-κB in lymphocytes from marathon runners which was completely prevented by allopurinol. In the rat model exercise caused an activation of MAP kinases in gastrocnemius muscle. This in turn activated the NF-κB pathway and consequently the expression of important enzymes associated with defence against ROS (superoxide dismutase) and adaptation to exercise (eNOS and iNOS). All these changes were abolished when ROS production was prevented by allopurinol.Conclusion. – Thus we report evidence that ROS act as signals in exercise because decreasing their formation prevents activation of important signalling pathways which cause useful adaptations in cells. Because these signals result in an up-regulation of powerful antioxidant enzymes, exercise itself can be considered as an antioxidant.     

模拟失重大鼠腹主动脉内皮依赖性舒张反应变化与氧化应激水平有关

目的探讨模拟失重大鼠腹主动脉内皮依赖性舒张反应的变化与氧化应激水平的关系。方法采用3周尾吊大鼠模型模拟失重状态,通过血管环张力实验检测内皮依赖性血管舒张反应,蛋白印迹技术以及DHE荧光探针技术观察悬吊(SUS)大鼠和正常对照(Con)大鼠动脉血管NOX4、p22phox蛋白表达及氧化应激水平变化。结果尾吊3周后,大鼠腹主动脉内皮依赖性舒张反应减弱,NADPH氧化酶抑制剂Apocynin以及超氧化物歧化酶SOD能够部分恢复舒张反应。SUS组腹主动脉活性氧簇(ROS)水平较Con组增高(P<0.05);腹主动脉p22phox蛋白表达悬吊组较对照组增高(P<0.05);NOX4蛋白表达两组间无明显变化。结论氧化应激水平增高可能与模拟失重所致腹主动脉内皮依赖性舒张反应减弱有关。     

过度训练对大鼠腹膜巨噬细胞活性氧生成能力的影响及其相关机制研究

目的:了解过度训练对巨噬细胞活性氧生成能力的影响及其相关机制。方法:8周龄健康雄性Wistar大鼠16只,随机分为安静对照组和过度训练组,每组8只。过度训练组进行11周递增负荷跑台训练,最后一次训练结束后36 h断头处死,分离纯化腹膜巨噬细胞。流式细胞术测定其活性氧(ROS)生成量,荧光定量PCR技术测定NADPH氧化酶gp91phox、p22phox、p47phox亚基和葡萄糖-6-磷酸脱氢酶(G6PD)基因表达。结果:与安静对照组相比,过度运动组巨噬细胞ROS生成量显著降低(P=0.003),gp91phox、p22phox亚基表达量无显著变化(P>0.05),p47phox亚基表达量显著增加(P<0.05),G6PD表达量无显著差异(P>0.05)。结论:过度训练可显著降低大鼠腹膜巨噬细胞ROS生成水平,这并非通过抑制NADPH氧化酶亚基表达和抑制NADPH氧化酶生成途径实现,可能有其它调控机制参与。     

Redox regulation of skeletal muscle glucose transport

Although the control of carbohydrate metabolism may be regulated by numerous factors, the redox state of the cell is of primary importance. The redox state may be influenced by a number of different factors, including different reactive oxygen species (ROS) and reactive nitrogen species (RNS) collectively, called reactive oxygen/nitrogen species (RONS). This review attempts to summarize the importance of redox regulation in relation to glucose transport and regulation of carbohydrate metabolism in skeletal muscle. In addition, prior studies implicating the role of different RONS in the control of glucose transport in skeletal muscle will be presented. Finally, the possible involvement of the cGMP, p21ras, and mean arterial pressure (MAP) kinase signal transduction cascades, which have been implicated with redox-sensitive alterations in glucose transport, will also be discussed.     

Antibacterial effect of singlet oxygen depending on bacteria surface charge

Here, we investigated the bactericidal effects of two types of photoinduced reactive oxygen species (ROS), superoxide anion and singlet oxygen, on bacteria with distinct surface charges. We fabricated photofunctional polymer films (PFPFs) capable of generating both types of ROS, and they were subjected to photodynamic inactivation tests for 12 various strains of Acinetobacter baumannii. The results showed that the type I ROS (superoxide anion) was significantly dependent on the surface charge of the bacteria owing to charge-charge repulsion, while the type II ROS (singlet oxygen) was independent of the surface charge of the bacteria. These results could be significant in enhancing treatment efficiency in the clinical field.     

Pulsed electromagnetic field (PEMF) prevents pro-oxidant effects of H2O2 in SK-N-BE(2) human neuroblastoma cells

Purpose The redox milieu, together with reactive oxygen species (ROS) accumulation, may play a role in mediating some biological effects of extremely-low-frequency electromagnetic fields (ELF-EMF). Some of us have recently reported that a pulsed EMF (PEMF) improves the antioxidant response of a drug-sensitive human neuroblastoma SH-SY5Y cell line to pro-oxidants. Since drug resistance may affect cell sensitivity to redox-based treatments, we wanted to verify whether drug-resistant human neuroblastoma SK-N-BE(2) cells respond to a PEMF in a similar fashion. Materials and methods SK-N-BE(2) cells were exposed to repeated 2?mT, 75?Hz PEMF (15?min each, repeated 3 times over 5 days), and ROS production, Mn-dependent superoxide dismutase (MnSOD)-based antioxidant protection and viability were assessed after 10?min or 30?min 1?mM hydrogen peroxide. Sham controls were kept at the same time in identical cell culture incubators. Results The PEMF increased the MnSOD-based antioxidant protection and reduced the ROS production in response to a pro-oxidant challenge. Conclusions Our work might lay foundation for the development of non-invasive PEMF-based approaches aimed at elevating endogenous antioxidant properties in cellular or tissue models.     

NADPH oxidase-produced superoxide mediated a 50-Hz magnetic field-induced epidermal growth factor receptor clustering

Purpose: A 50-Hz magnetic field (MF) was found to induce epidermal growth factor receptor (EGFR) clustering in our previous study. The aim of this work was to investigate the molecular mechanisms that mediated MF-induced EGFR clustering.

Materials and methods: Human amniotic epithelial (FL) cells were exposed to a 50-Hz MF. Total reactive oxygen species (ROS), cytoplasmic and mitochondrial superoxide production were detected by DCFH-DA, DHE and MitoSOX, respectively. EGFR clustering was analyzed using confocal microscopy after indirect immunofluorescence staining.

Results: Results showed that exposing FL cells to MF at intensity higher than 0.2?mT for 15?min enhanced total ROS production. Additionally, enhanced total ROS and cytoplasmic superoxide production were observed after exposing cells to MF at 0.4?mT for 5, 15, or 30?min, while mitochondrial superoxide production for 15 or 30?min. Pretreatment with Nox inhibitor, DPI, effectively inhibited MF-induced cytoplasmic superoxide production and subsequent EGFR clustering while mitochondrial superoxide production was not affected.

Conclusions: Nox-produced superoxide mediated a 50-Hz magnetic field-induced EGFR clustering.     

Antioxidants and exercise.

Muscular exercise results in an increased production of radicals and other forms of reactive oxygen species.Further more, growing evidence implicates cytotoxic ROS as an underlying cause in exercise-induced disturbances in muscle redox status that could result in muscle fatigue or injury. Muscle cells contain complex cellular defense mechanisms to minimize the risk for oxidative injury. Two major classes of endogenous protective mechanisms work together to reduce the harmful effects of oxidants in the cell: (1) enzymatic and (2) nonenzymatic antioxidants. Key antioxidant enzymes include superoxide dismutase, glutathione peroxidase, and catalase. These enzymes are responsible for removing superoxide radicals, hydrogen peroxide or organic hydroperoxides, and hydrogen peroxide, respectively. Important nonenzymatic antioxidants include vitamins E and C, beta-carotene, GSH, uric acid, ubiquinone, and bilirubin. Vitamin E, beta-carotene, and ubiquinone are located in lipid regions of the cell, whereas uric acid, GSH, and bilirubin are in aqueous compartments of the cell. Although numerous animal experiments have demonstrated that the addition of antioxidants can improve muscular performance, to date, limited evidence shows that dietary supplementation with antioxidants improves human performance. This is an important area for future research.     

线粒体靶向药物的研究进展

电离辐射产生的活性氧（ROS）和自由基攻击DNA、脂质、蛋白质等生物大分子,造成机体细胞和组织的损伤。体内ROS主要来自线粒体,辐射造成线粒体损伤,使细胞内ROS持续增加。线粒体靶向抗氧化剂由于靶向在线粒体释放,能够高效地消除辐射导致的线粒体内过量ROS,保护线粒体,降低电离辐射对细胞的损伤,被认为是一类有前景的辐射损伤防护药。近年来,文献报道了多种线粒体靶向给药系统,笔者主要分析了线粒体靶向给药系统的方法及其发展趋势以及在辐射防护上的应用潜能。     

Pressure and temperature interactions on aerobic metabolism in migrating silver eels: results in vitro.

The European eel (Anguilla anguilla) migrates (6000 km) from European coast towards the supposed spawning area: the Sargasso Sea. This intensive and sustained swimming activity is performed without feeding and by using essentially red muscle i.e. aerobic metabolism. Temperature and hydrostatic pressure vary during migration and have known effects on energy metabolism, mainly on mitochondrial functioning. We raise the question about the existence of a pressure-temperature combination that optimizes energy metabolism. We have measured the maximal oxygen consumption (MO2) of red muscle fibres of silver eel (migrating stage) in a temperature range (5 to 25 degrees C) covering what can be reasonably expected during the migration. We have combined (random order) three temperatures (5, 15, 25 degrees C) with 5 different pressures steps from 0.1 to 10.1 MPa (corresponding to depths from surface to 1000 m). The results show that when an adequate temperature is chosen as a reference, pressure effects and pressure sensitivity depend on the temperature. Based on the fact that energy budget is limited in migrating eels, we consider that the best conditions are low temperature and high pressure.     

Fundamental model assays on chemical damages to ribonucleic acids caused by oxygen radicals in aqueous solution

A partial decomposition of RNA molecules in Saccharomyces cerevisiae is caused by photochemically produced superoxide anion radical (O2-.). Hydroxyl radicals (OH.) lead to complete destruction of RNA. Such radicals as originating from peroxidase-hydrogen peroxide reaction cause a partial decomposition of RNA molecules. All RNA species are damaged to the same extent by radicals. Damages due to oxygen radicals can be prevented or reduced by strong radical captors (dimethyl sulfoxide, 1,4-diazabicyclo-(2,2,2)-octane or superoxide dismutase). All these reactions proceed in aqueous solution. Correlations with the use of radicals in radiotherapy are discussed.     

Contraction-induced oxidants as mediators of adaptation and damage in skeletal muscle

Contracting skeletal muscle generates reactive oxygen and nitrogen species (ROS) that can induce changes in gene expression or cell damage depending upon the pattern of production and the endogenous protective systems. The hypothesis is presented that skeletal muscle uses contraction-induced ROS as signals to induce adaptive responses including maintenance of oxidant homeostasis and prevention of oxidative damage.     

葛根素对氧自由基的清除和抗氧化性损伤作用

目的　研究葛根素 (Puerarin ,Pue)对氧自由基的清除以及抗氧化性损伤作用。方法　以核黄素 -光系统产生超氧阴离子 ,Fenton反应产生羟自由基 (·OH) ,研究Pue对氧自由基的清除作用 ;以过氧化氢 (H2 O2 )引起红细胞溶血 ,黄嘌呤 -黄嘌呤氧化酶 (X -XOD)致豚鼠心室乳头肌损伤 ,研究Pue的抗氧化性损伤作用。结果　Pue能清除超氧阴离子和·OH ;抑制H2 O2 引起红细胞溶血和脂质过氧化物生成 ;增强心室乳头肌超氧化物歧化酶 (SOD)活性 ,降低丙二醛 (MDA)含量 ,保护乳头肌免受超氧阴离子的损伤。结论　Pue对氧自由基有清除作用 ,并能预防性对抗H2 O2 和超氧阴离子引起的氧化性损伤     

Nitric oxide, reactive oxygen species, and skeletal muscle contraction

Nitric oxide (NO) derivatives and reactive oxygen species (ROS) modulate contractile function of respiratory and limb skeletal muscle. The intracellular processes regulated by NO and ROS remain enigmatic, however. Studies of reduced preparations have identified a number of regulatory proteins that exhibit altered function when exposed to exogenous NO or ROS donors ex vivo. The relative importance of these targets in the intact cell is not known and conflicting theories abound regarding the mechanism(s) whereby NO and ROS regulate contraction. This review article provides a personal perspective on the processes regulated by NO and ROS by addressing three major topics: 1) the regulatory mechanisms by which endogenous NO depresses force production, 2) the processes whereby endogenous ROS modulate contraction of unfatigued muscle, and 3) the site(s) of action and reversibility of ROS effects in muscle fatigue.     

The relationship of oxygen uptake to superoxide dismutase and catalase activity in human skeletal muscle

A considerable amount of evidence now makes it clear that aerobic tissues require an elaborate enzyme system to remove the harmful reaction products of oxygen reduction. A portion of this protective system has been studied in human muscle and rat tissues. The VO2 max as well as the superoxide dismutase and catalase activity of vastus lateralis muscle of 12 healthy, male subjects was measured. The subjects with a high aerobic capacity (VO2 max greater than 60 ml . kg-1 . min-1) had significantly greater levels of both superoxide dismutase and catalase. There was also a linear relationship between both superoxide dismutase and catalase and VO2 max. The tissue oxygen consumption, and enzyme activity of the liver, heart, lung, and gastrocnemius from 24 rats was also studied. There VO2 and tissue enzyme activity of both superoxide dismutase and catalase.     

Fe~(2+)-次黄嘌呤-黄嘌呤氧化酶产生的活性氧损伤脱氧核糖的研究

Fe~(2+)-次黄嘌呤-黄嘌呤氧化酶体系产生的活性氧能诱发脱氧核糖的损伤,使之转变为硫代巴比妥酸反应物(TBAS).增加黄嘌呤氧化酶或脱氧核糖的浓度都增加TBAS的生成量.Fe~(2+)促进TBAS的生成,此促进作用随着Fe~(2+)浓度的升高而很快达到饱和.超氧化物歧化酶(SOD)或过氧化氢酶(CAT)都能抑制TBAS的生成.间接证明体系中的TBAS是由活性氧攻击脱氧核糖而形成的.并且羟自由基是起主要作用的活性氧.     

Exercise training-induced alterations in skeletal muscle antioxidant capacity: a brief review.

Cellular oxidants include a variety of reactive oxygen, nitrogen, and chlorinating species. It is well established that the increase in metabolic rate in skeletal muscle during contractile activity results in an increased production of oxidants. Failure to remove these oxidants during exercise can result in significant oxidative damage of cellular biomolecules. Fortunately, regular endurance exercise results in adaptations in the skeletal muscle antioxidant capacity, which protects myocytes against the deleterious effects of oxidants and prevents extensive cellular damage. This review discusses the effects of chronic exercise on the up-regulation of both antioxidant enzymes and the glutathione antioxidant defense system. Primary antioxidant enzymes superoxide dismutase, glutathione peroxidase, and catalase will be discussed as well as glutathione, which is an important nonenzymatic antioxidant. Growing evidence indicates that exercise training results in an elevation in the activities of both superoxide dismutase and glutathione peroxidase along with increased cellular concentrations of glutathione in skeletal muscles. It seems plausible that increased cellular concentrations of these antioxidants will reduce the risk of cellular injury, improve performance, and delay muscle fatigue.     

氧化应激在低压缺氧性肺动脉高压形成中的作用

目的观察低氧对血清中活性氧(ROS)水平的影响,探讨氧化应激在低压缺氧性肺动脉高压形成中的作用。方法将24只Wistar大鼠随机分为平原对照组(C组),缺氧组(H组),N-乙酰半胱氨酸组(N组),缺氧+N-乙酰半胱氨酸组(H+N组)。建立低压缺氧模型21 d后,测定其右心室收缩压(RVSP)和平均肺动脉压(mPAP);HE染色观察各组大鼠的肺动脉壁厚度;比色法测定血清中ROS的含量。结果与C组相比,H组RVSP、mPAP明显升高(均P<0.05),HE染色示H组肺动脉壁增厚,且血清中ROS水平明显升高(P<0.05);给予ROS清除剂NAC后,RVSP及mPAP降低,肺血管重塑减弱。结论低氧时氧化应激参与了低压缺氧性肺动脉高压的形成。     

Effects of nerve growth factor on antioxidative system in the thalamus of MPTP treated Wistar rats

1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced parkinsonism is one of the most useful models for the study of that disease. It has been suggested that MPTP-induced neurotoxicity may involve the production of reactive oxygen species. MPTP was applied intracerebrally, unilaterally, in the striatum in single dose of 0.09 g/kg b.w. The second group was treated both with MPTP and nerve growth factor (NGF) in dose of 7 ng/ml. NGF was applied immediately after the neurotoxin. Control group was treated with 0.9% saline solution in the same manner. Animals were decapitated 7 days after the treatment. In the group treated with MPTP, the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) was decreased in ipsilateral thalamus, compared to control values as well as to the contralateral thalamus. In the same structures superoxide anion production was increased, compared to controls. Following the application of both MPTP and NGF, the activity of SOD and GSH-Px remained on control values, while the superoxide anion content was decreased, compared to controls. These results indicate a temporal and spatial propagation of oxidative stress and spread protective effects of NGF on the thalamus, the structure that is distant, but very tightly connected with striatum, the place of direct neurotoxic damage.