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Effect of paraquat on cellular defense enzymes and glutathione level of Funalia trogii.

The effect of paraquat on the activities of antioxidant defense and detoxifying enzymes of the white-rot fungus Funalia trogii was determined. Paraquat increased the activities of glutathione reductase (GR), glutathione transferase (GT) and superoxide dismutase at 1 mmol/L, while at 0.1 mmol/L it did not affect the activity of GR and GT. It depressed the catalase activity and the amount of glutathione at all concentrations used. Paraquat treatment probably depresses antioxidant defense components such as catalase and glutathione.

Antioxidants↗

Glutathione and glutathione-linked enzymes in normal human aortic smooth muscle cells: chemical inducibility and protection against reactive oxygen and nitrogen species-induced injury.

Substantial evidence suggests a crucial role for glutathione (GSH) and GSH-linked enzymes in protecting against oxidative vascular disorders. However, studies on the chemical inducibility of these antioxidant defenses and their protective effects on oxidant injury in normal human vascular cells are currently lacking. Accordingly, this study was undertaken to investigate the inducibility of GSH, glutathione reductase (GR), glutathione peroxidase (GPx), and glutathione S-transferase (GST) by the chemoprotective agent, 3H-1,2-dithiole-3-thione (D3T) in cultured normal human aortic smooth muscle cells (HASMCs). HASMCs expressed measurable levels/activities of GSH, GR, GPx, and GST. Incubation of HASMCs with low micromolar concentrations of D3T resulted in a marked elevation in total cellular GSH content and GR activity. The protein and mRNA expression of gamma-glutamylcysteine ligase (GCL) and GR were also upregulated by D3T. In addition, D3T caused significant increases in mitochondrial GSH content and GR activity. In contrast, neither cellular GPx nor GST activity was altered after D3T treatment. Pretreatment of HASMCs with D3T afforded remarkable protection against reactive oxygen and nitrogen species (ROS/RNS)-mediated cell injury. Depletion of cellular GSH by pretreatment with buthionine sulfoximine (BSO), an inhibitor of GSH biosynthesis led to marked potentiation of the ROS/RNS-induced cell injury. Moreover, co-treatment of HASMCs with BSO was found to completely abolish the D3T-mediated GSH elevation, and remarkably reverse D3T cytoprotection against the ROS/RNS-elicited injury. Taken together, this study demonstrates that both GSH/GCL and GR in normal HASMCs are inducible by D3T, and that upregulation of GSH biosynthesis appears to be the predominant mechanism underlying D3T-mediated cytoprotection against ROS/RNS-elicited injury to human vascular smooth muscle cells.

Antineoplastic Agents↗

Distribution of glutathione and glutathione-related enzyme systems in mitochondria and cytosol of cultured cerebellar astrocytes and granule cells.

The cellular and regional distribution of glutathione (GSH) and GSH-related enzyme systems involved in cellular defense against reactive oxygen species and electrophilic xenobiotics in the nervous system has been extensively studied. However, little is known about the subcellular distribution of GSH systems in brain tissue and cultured neural cells. The present study investigates the distribution of mitochondrial and cytosolic GSH and GSH-related enzymes in cultured cerebellar astrocytes and granule cells, and compares them with levels in the adult rat cerebellum. Cytosolic GSH levels and cytosolic activities of glutathione reductase (GR), glutathione peroxidase (GPX) and glutathione-S-transferase (GST) in astrocytes were 57, 153, 245, and 92% higher than those found in granule cells, respectively. In contrast, granule cells contained significantly higher mitochondrial GSH levels than astrocytes. Granule cells also demonstrated comparable mitochondria/cytosolic concentrations of GSH and GR, GPX and GST activities to those observed in the cerebellar tissue, whereas ratios in astrocytes were markedly lower. Although in vitro treatments with 100 microM ethacrynic acid depleted both cytosolic and mitochondrial GSH in cultured astrocytes and granule cells in a time-dependent fashion, cellular GSH in granule cells was more resistant to the GSH-depleting agent than astrocytes. These results suggest that although GSH and GSH-related enzymes are abundant in cytosolic compartments of astrocytes, mitochondrial pools are relatively small. Since brain mitochondria are sites of significant hydrogen peroxide generation, the mitochondrial localization of GSH and its associated enzymes in neural cells provide important defenses against toxic oxygen species in the nervous system. Differences in subcellular distribution of GSH systems in individual neural cell types may provide a basis for selective cellular and/or subcellular expression of neurotoxicity.

Animals↗

Schistosoma mansoni: levels of antioxidants and resistance to oxidants increase during development.

The effects of cell-free generated oxidants on migrating and developing stages of Schistosoma mansoni were investigated and the levels of antioxidant enzymes and of glutathione were determined for each stage. Schistosomula and 2-week-old parasites recovered from the livers of infected mice showed similar susceptibility to killing by added hydrogen peroxide and t-butylhydroperoxide. However, when glucose (0.5 mM)-glucose oxidase (2.5 mU ml-1) and xanthine (0.5 mM) or hypoxanthine (0.5 mM)-xanthine oxidase (5.0 mU ml-1) systems were used to generate hydrogen peroxide and oxygen free-radicals, schistosomula were more susceptible to oxidative killing than the 2-week-old parasites. The 4- and 8-week-old worms were more resistant to oxidants than all of the younger stages. High levels of superoxide dismutase (16.2-24.8 U mg-1 protein) were present in all stages. Catalase was not detected. Glutathione peroxidase activity with cumene hydroperoxide as substrate was not detectable in the schistosomula but the activity was present in the 2-week-old parasites. However, hydrogen peroxide-sensitive glutathione peroxidase activity was present in all the stages with a threefold difference in activity between schistosomula and the adult stages. Glutathione-s-transferase activity was significantly lower in the schistosomula, lung stages, and the 2-week-old parasites than in the older stages. Progressive increases in the levels of glutathione reductase and glutathione were also observed with development. The differences in the levels of antioxidants between different stages of development may partly explain the increase in resistance to oxidant-mediated damage as the parasite develops.

Animals↗

Oxidative damage and changes in the glutathione redox system in erythrocytes from rats treated with hexachlorocyclohexane.

The concentration of reduced glutathione in the erythrocytes of rats was significantly decreased 24-72 hr after the rats were treated with 300 mg commercial hexachlorocyclohexane/kg body weight (one-third of the LD50), given ip. The activities of glutathione reductase, glutathione-S-transferase and glucose-6-phosphate dehydrogenase were also significantly decreased 24 hr after treatment but there was no change in glutathione peroxidase activity. The results suggest that hexachlorocyclohexane produces significant changes in the glutathione redox system of rat erythrocytes leading to oxidative membrane damage.

Animals↗

Translactational exposure of F1 mouse pups to selenium.

In an investigation of the modulation of certain neonatal xenobiotic-metabolizing enzymes in liver of mouse pups postnatally exposed to selenium through the transmammary route, sodium selenite was administered in drinking water to lactating dams at the dose levels of 1 or 5 ppm from day 1 of lactation and continued daily for 14 or 21 days. The higher dose of selenium was found to increase the hepatic acid-soluble sulfhydryl content significantly after 21 days of treatment in dams, their pups (P < 0.01) and in the 14-day-old male pups (P < 0.05). Cytochrome b5 content decreased in the livers of dams that received 5 ppm selenium (P < 0.01) and in the F1 pups (P < 0.01) translactationally exposed to selenium for 14 days. Cytochrome P-450 content decreased in dams and pups exposed to 5 ppm selenium for 14 days and either dose for 21 days (P < 0.01). Hepatic glutathione S-transferase decreased in the dam that had received 5 ppm selenium for 14 days (P < 0.05) and in the 14-day-old pups (P < 0.01). Glutathione reductase and glutathione peroxidase activities decreased in both dams and pups (P < 0.01). The overall suppression of neonatal hepatic detoxification enzymes demonstrates that selenium may have far-reaching consequences on neonatal growth, development and drug pharmacokinetics.

Animals↗

Effect of asoka on the intracellular glutathione levels and skin tumour promotion in mice.

The bark of Saraka asoca (asoka) is commonly used to treat various diseases by the Indian system of medicine and in Sri Lanka. Further purification and chemical analysis of the active compound from the bark extract of asoka showed that (-)-epicatechin was responsible for the observed antitumour/anticarcinogenic activity. Papilloma formation in mice initiated with 7,12-dimethylbenz[a]anthracene (DMBA) and promoted using croton oil was inhibited by the topical application of 100 mg/kg body weight (b.w.) of (-)-epicatechin isolated from asoka bark extract. Oral administration of the same dose restricted the growth of s.c. injected 20 methylcholanthrene (MCA) induced soil tissue fibrosarcomas significantly in mice. Elevations of almost 2-4-fold in the intracellular reduced glutathione and related enzymes viz., glutathione reductase and glutathione S-transferase of sarcoma-180 tumour cells were noted in the presence of 1 microgram/ml of (-)-epicatechin, further highlighting its antiproliferative effect.

9,10-Dimethyl-1,2-benzanthracene↗

Sensitivity analysis and error structure of progress curves.

Both the sensitivity of the monitored signal in progress curves to variations in enzyme concentration and the standard deviation of this signal were analyzed as a function of the proportion of transformed substrate. Three enzymes catalyzing essentially irreversible reactions were used as model systems: HIV-1 protease, glutathione reductase, and glutathione transferase. For all enzymes analyzed, the sensitivity was maximal when 60-80% of the substrate had been transformed. The standard deviation of reaction progress curve data replicates was also maximal at these substrate conversion levels, a result that was attributed to the influence of the sensitivity to random dispersion of the enzyme concentration. On this basis, we developed a model for the standard deviation of reaction progress curves that gave a good description of the experimental data and efficiently reduced the heteroscedasticity of residuals in a weighted fit of progress curves. This standard deviation model can be used for obtaining more efficient parameter estimates, to simulate noise in Monte Carlo procedures, and to delineate detection limits of enzyme inhibition. The transient increases in the sensitivity and in the standard deviation in progress curves are proposed to be features common to most enzymatic assays.

Calibration↗

Time-course variations of oxyradical metabolism, DNA integrity and lysosomal stability in mussels, Mytilus galloprovincialis, during a field translocation experiment.

Harbours can be considered as model environments for developing and validating field monitoring procedures and to investigate mechanistic relationships between different biological responses. In this study, several biomarkers were investigated in marine mussels caged for 4 weeks into an industrialised harbour of north-west Italy. Organisms were collected at different time intervals to better characterise the sensitivity, temporal variations and interactions of analysed responses. Besides single antioxidants (catalase, glutathione S-transferases, glutathione reductase, total glutathione), the total oxyradical scavenging capacity (TOSC) assay was used to analyse the capability of the whole antioxidant system to neutralise specific forms of radicals: these data were further integrated by measurement of DNA integrity, oxidised bases and the impairment of lysosomal membrane stability in haemocytes. Results showed a biphasic trend for single antioxidants and TOSC, with no variation or increase during the first 2 weeks of exposure to the polluted site followed by a progressive decrease up to a severe depletion in the final part of the experiment. These findings suggest an initial counteractive response of mussels toward the enhanced prooxidant challenge, while antioxidants appeared overwhelmed at longer exposure periods. The hypothesis of reactive oxygen species (ROS) mediated toxicity is supported by the appearance of cell damages (DNA integrity and lysosome membrane stability), which exhibited a progressive enhancement during the course of the experiment with a maximum impairment after 30 days of exposure.

Analysis of Variance↗

Determination of photosynthetic and enzymatic biomarkers sensitivity used to evaluate toxic effects of copper and fludioxonil in alga Scenedesmus obliquus.

Modulated PAM fluorometry and Plant Efficiency Analyser methods were used to investigate photosynthetic fluorescence parameters of alga Scenedesmus obliquus exposed to inhibitory effect of fungicides copper sulphate and fludioxonil (N-(4-nitrophenyl)-N'-propyl-uree). The change of those parameters were studied when alga S. obliquus have been exposed during 48 h to different concentrations of fungicides (1, 2 and 3 mgl(-1)). Under the same condition, enzymatic activities of catalase, ascorbate peroxidase, glutathione reductase and glutathione S-transferase were investigated to evaluate antioxidative response to fungicides effects. The change of sensitivity of those parameters was dependent to the mode of fungicide action, their concentration and time of exposure. For copper effects, the most indicative photosynthetic biomarkers were parameters Q(N) as non-photochemical fluorescence quenching, Q(Emax) as the proton induced fluorescence quenching and ABS/RC as the antenna size per photosystem II reaction center. Copper induced oxidative stress was indicated by increased activity of catalase serving as the most sensitive and valuable enzymatic biomarker. On the other hand, fludioxonil effect on photosynthetic parameters was very negligible and consequently not very useful as biomarkers. However, fludioxonil induced strong antioxidative activities associated with cytosol enzymes, as we found for catalase, ascorbate peroxidase and glutathione S-transferase activities. By obtained results, we may suggest for the activation of those enzymes to be sensitive and valuable biomarkers of oxidative stress induced by fludioxonil. Determination of biomarkers sensitivity may offer advantages in providing real criteria to use them for ecotoxicological diagnostic studies.

Ascorbate Peroxidases↗

Lead induced changes in antioxidant metabolism of horsegram (Macrotyloma uniflorum (Lam.) Verdc.) and bengalgram (Cicer arietinum L.).

One-month old horsegram (Macrotyloma uniflorum (Lam.) Verdc. cv VZM1) and bengalgram (Cicer arietinum L. cv Annogiri) were exposed to different regimes of lead stress as Pb(NO3)2 at 0, 200, 500 and 800 ppm concentrations. The extent of oxidative damage as the rate of lipid peroxidation, antioxidative response and the accumulation of lead in roots and shoots of both plants were evaluated after 12 days of lead stress. Lead (Pb) treated plants showed increased levels of lipid peroxidation as evidenced from the increased malondialdehyde content coupled with the increase in the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione reductase (GR), glutathione S-transferase (GST) compared to control (untreated) plants. Lead stress caused significant changes in the activity of antioxidative enzymes. The effect of lead was found to be concentration dependent. Higher concentration of lead (800 ppm) resulted 2- to 3-fold increase in SOD, catalase and peroxidase activities, 3- to 5-fold increase in GR activity and 3- to 4-fold increase in GST activity in roots and leaves of both horsegram and bengalgram plants. Lead stress caused a significant increase in the rate of peroxidation as showed in the levels of malondialdehyde content in roots and leaves of both plant species. Horsegram registered lower Pb accumulation than bengalgram, however localization of Pb was greater in roots than leaves in both plants. In general, lipid peroxide levels and antioxidative enzyme activities were higher in horsegram than bengalgram and also more in roots than leaves which best concordance with the lead contents of both the plants and organs. These results suggest that Pb toxicity causes oxidative stress in plants and the antioxidative enzymes SOD, CAT, POD, GR, GST could play a pivotal role against oxidative injury.

Antioxidants↗

Glutathione levels and enzyme activity in the tissues of bank vole Clethrionomys glareolus chronically exposed to a mixture of metal contaminants.

The biochemical response to chronic heavy metal exposure was studied in tissues of bank voles Clethrionomys glareolus. Animals were collected from three sites located 4, 8 and 30km from a zinc-lead smelter, the area's main source of metal contamination. Concentrations of Cd, Pb, Zn and Fe were measured in the liver, kidneys and gonads to assess the level of metal intoxication. In response to intoxication, organisms activate detoxification mechanisms which can protect animals from metals' toxicity. Glutathione plays an important role in toxic substance detoxification. Total glutathione (tGSH) and glutathione disulfide (GSSG) were measured in the tissues. Also, the activity of glutathione reductase (GR), glutathione peroxidase (GPX), and glutathione-S-transferase (GST) was measured in the studied tissues. Results indicate that levels of all studied parameters were tissue and site-dependent. Evidence indicates that the most sensitive parameter of metal toxicity for animals living in a chronically contaminated environment is the GSH/GSSG ratio. In our study, the GSH/GSSG ratio was decreased in the liver of animals with high Cd levels. However, the relationship between Pb and the GSH/GSSG ratio was positive in the gonads. Cadmium and lead negatively influenced GPX activity in the liver; this was probably connected with inhibition of the Se-dependent fraction. The relationship between iron and GR activity in the kidney was also negative, but other correlations for iron both in liver and kidney were not significant. Positive correlations between Zn levels and GST and GR activity were found in the gonads of bank voles.

Animals↗

Antioxidant responses to benzo[a]pyrene and Aroclor 1254 exposure in the green-lipped mussel, Perna viridis.

In this study, the green-lipped mussel, Perna viridis (L.), was exposed to two concentrations of benzo[a]pyrene (B[a]P) (0.3 microg l(-1); 3 microg l(-1)) and two concentrations of Aroclor 1254 (0.5 microg l(-1); 5 microg l(-1)). In addition, a mixture of the contaminants was used (0.3 microg l(-1) B[a]P+0.5 microg l(-1) Aroclor 1254; 3 microg l(-1) B[a]P+5 microg l(-1) Aroclor 1254). All concentrations were nominal. A suite of enzymes [glutathione S transferase (GST), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR)], glutathione (GSH) level and lipid peroxidation (LPO) in the mussel gill and hepatopancreas were monitored over 18 days. CAT and GSH in gill tissue were positively correlated with concentration of Aroclor 1254. Activity of hepatic GST and SOD was significantly related to body burden of Aroclor 1254. LPO, GR and GPx in gill and hepatopancreas and hepatic GST were positively correlated with B[a]P concentration. The results indicate the importance of using biomarkers specific to the type of contaminant(s) that are likely to be present. Controlled laboratory experiments, such as this study, are useful in ascertaining biomarkers suitable for use with complex contaminant mixtures in the marine environment.

Animals↗

Pro-oxidant activity of aluminum in the rat hippocampus: gene expression of antioxidant enzymes after melatonin administration.

Aluminum (Al)-induced pro-oxidant activity and the protective role of exogenous melatonin, as well as the mRNA levels of some antioxidant enzymes, were determined in the hippocampi of rats following administration of Al and/or melatonin. Two groups of male rats were intraperitoneally injected with Al (as Al lactate) or melatonin only, at doses of 7 and 10 mg/kg/day, respectively, for 11 weeks. During this period, a third group of animals received Al (7 mg/kg/day) plus melatonin (10 mg/kg/day). At the end of the treatment, hippocampus was removed and processed to examine the following oxidative stress markers: glutathione transferase (GST), reduced glutathione (GSH), oxidized glutathione (GSSG), superoxide dismutase (SOD), glutathione reductase (GR), glutathione peroxidase (GPx), catalase (CAT), thiobarbituric acid reactive substances (TBARS), as well as protein content. Gene expression of Cu-ZnSOD, MnSOD, GPx, and CAT was evaluated by real-time RT-PCR. On the other hand, Al, Fe, Mn, Cu, and Zn concentrations in hippocampus were also determined. The results show that Al exposure promotes oxidative stress in the rat hippocampus, with an increase in Al concentrations. The biochemical changes observed in this tissue indicate that Al acts as pro-oxidant agent, while melatonin exerts antioxidant action by increasing the mRNA levels of the antioxidant enzymes evaluated. The protective effects of melatonin, together with its low toxicity and its capacity to increase mRNA levels of antioxidant enzymes, suggest that this hormone might be administered as a potential supplement in the treatment of neurological disorders in which oxidative stress is involved.

Aluminum Compounds↗

Mannosylated liposomal flavonoid in combating age-related ischemia-reperfusion induced oxidative damage in rat brain.

Active oxygen species alter the activities of the enzymes involved in the defence against free radicals and substantially influence the aging process and age-dependent neuropathology. Unilamellar liposomes were used to deliver flavonoidal antioxidant quercetin (QC) to rat brain. Antioxidant potential of QC loaded in mannosylated (QC 7.2 micromol/kg b.wt.) liposomes (50 nm) was investigated by an in vivo model of cerebral ischemia and reperfusion on Sprague Dawley young (2 months old, b.wt. 160-180 g) and aged (20 months old, b.wt. 415-440 g) rats. Animals were made ischemic for 30 min by bilateral clamping of the common carotid artery followed by a 30 min cerebral reperfusion by withdrawing the clamping. Diene level and (GSSG/GSH) ratio were found to be higher in normal aged, compared to normal young rat brain. Superoxide dismutase, catalase, glucose-6-phosphate dehydrogenase, glutathione reductase and glutathione S-transferase activities were lower in normal aged rat brain. Further reduction of these antioxidant enzymes was observed in aged rat brain by the induction of cerebral ischemia and reperfusion. Mannosylated liposomally encapsulated QC treatment resulted in a significant preservation of the activities of antioxidant enzymes and a marked inhibition of cellular edema formation in neuronal cells of young and old rats.

Aging↗

Antioxidant defenses and lipid peroxidation in the cerebral cortex and hippocampus following acute exposure to malathion and/or zinc chloride.

This study investigates the effects of acute exposure to organophosphate insecticide malathion (250 mg/kg, i.p.) and/or ZnCl2 (5 mg/kg, i.p.), with the following parameters: lipid peroxidation and the activity of acetylcholinesterase (AChE), glutathione reductase (GR), glutathione S-transferase (GST), glutathione peroxidase (GPx), glucose-6-phosphate dehydrogenase (G6PDH), and the levels of total glutathione (GSH-t) in the hippocampus and cerebral cortex of female rats. Malathion exposure elicited lipid peroxidation and reduced AChE activity in the cerebral cortex and hippocampus. It also reduced the activity of GR and GST, and increased G6PDH activity in the cerebral cortex, without changing the levels of GSH-t and GPx activity. ZnCl2 exposure reduced AChE activity and caused a mild pro-oxidative effect, since lipid peroxidation was increased in the hippocampus. ZnCl2, individually or in combination with malathion, caused a reduction in GR and GST activity in the cerebral cortex. Malathion and/or ZnCl2 did not change the GSH-t levels. Moreover, ZnCl2 prevented the increase in G6PDH activity caused by malathion. It showed that ZnCl2 had little effect against the changes induced by malathion. In fact, zinc itself produced pro-oxidant action, such as the reduction in the activity of the antioxidant enzymes GR and GST.

Acetylcholinesterase↗

Effect of food deprivation on oxidative stress biomarkers in fish (Sparus aurata).

Oxidative stress in fish (Sparus aurata) as a consequence of food restriction and fasting, has been studied. Four groups of fish were maintained for 46 days under different conditions of food supplementation: a control group with no food restriction (ratio of food/fish of 2% w/w), two groups of animals with restricted food supplement (1 and 0.5%) and a fasting group (no meal addition). Finally, all the fish were provided with food at the same ratio as the control group for the last 7 days. Sampling and weighing of fish were carried out every week and their livers were used for the analysis of known biomarkers of oxidative stress. Malondialdehyde and oxidized glutathione levels increased at the third week in fish with partial or total food deprivation, but these levels returned to normal values when the fish readapted to the control conditions. Antioxidant enzymes were also analyzed and significant increases in superoxide dismutase (SOD), glutathione reductase and glutathione peroxidase activities were found in parallel with food restriction; however catalase activity decreased in fasting fish. New SOD isoforms were detected by isoelectrofocusing in fish under food restriction at the second week, which disappeared when starved fish returned to the control conditions. These new SOD isoforms were detected before the appearance of other usual oxidative stress biomarkers.

Animals↗

NGF prevents changes in rat brain glutathione-related enzymes following transection of the septohippocampal pathway.

The activities of the enzymes glutathione reductase (GRD), glutathione peroxidase (GPX), and glutathione S-transferase (GST) were studied in several rat brain areas following the aspirative transection of the septohippocampal pathway (fimbria fornix) and the administration of nerve growth factor (NGF) or cytochrome c. One group of animals remained untreated. This lesion resulted in a decreased hippocampal GRD and septal GST activities, as well as, in an increase in GPX activity from the frontal cortex, striatum, and septum. NGF prevented the lesion-induced changes in hippocampal GRD and septal GPX. These findings show that the insult resulting from the aspiration of the fimbria fornix bundle involves modifications in glutathione-related enzymes, and, therefore, in the antioxidant status of brain tissue. These changes in glutathione metabolism could be a consequence of the oxidative damage to GRD and GST proteins or represent a compensatory response of GPX to the oxidative threat The restoring effects of NGF on altered enzyme activities are possibly linked to its known neuroprotective action.

Animals↗