Analyses of impact of metal ion contamination on carp (Cyprinus carpio L.) gill cell suspensions

The decline in fish population because of water contamination is problem. As a result of direct exposure in water, it has been readily accepted that the gills are the main site of water contamination and toxicity (e.g., metal ions). In the present study, we investigated metal ion contamination on the functional capacity of carp gill cells with antioxidant interactions in an in vitro study. The extent of cellular membrane damage, lipid peroxidation (LPO) (as TBARS levels), and glutathione (GSH) content were investigated after the addition of two metal ion compounds (viz., CuSO₄ and HgCl₂) in various concentrations (300, 500, 700, 1000, and 3000 μM) to gill cell preparation of the freshwater fish carp (Cyprinus carpio L.) with modulations by bovine serum albumin (BSA) (0.5% and 1.0%) and dimethyl sulfoxide (DMSO) (0.5%) as free-radical scavengers. The Comet assay technique was also performed for the highest concentrations of the two mentioned metal ions as an index of DNA breaks. The outcomes were as follows: (1) Copper and mercury increased the rate of LPO dose dependently (r=+0.995 and r=+0.993, respectively; p<0.001), but the GSH content was only marginally affected (r=−0.787 and r=−0.844, respectively; p<0.05). (2) Depletion of GSH molecules by copper had a wider range than mercury. (3) In the highest concentration of metal ions (3000 μM), both DMSO and 1.0% BSA showed a pro-oxidative potential to elevate the levels of TBARS (p<0.001), but for other concentrations when supplemented with three scavengers, a fall in the levels of the latter was found. (4) The addition of 1.0% BSA to medium containing 3000 μM of metal ions caused a significant decline in GSH content (p<0.01). (5) Copper and mercury could cause a high rate of DNA breaks (single stranded) in carp gill cell suspensions as a Comet appearance. These findings indicate that copper and mercury have a deleterious influence on membrane integrity and GSH content in a relatively dose-dependent manner. The complexes of metal ions and thiol (−SH) residues of cell proteins could also act as a potential cell toxicant leading to disturbances in cell functions causing cell death. DNA fragmentation is frequent in metal ion contamination.     

Oxidative stress and genotoxic effects in gill and kidney of Anguilla anguilla L. exposed to chromium with or without pre-exposure to beta-naphthoflavone

Fish in the aquatic environment can be subjected to a multipollution state and the occurrence of sequential exposures is an important aspect of eco-toxicological research. In this context, a preceding exposure can affect a toxic response to a subsequent exposure. Therefore, the current study was based on sequential exposures, viz. to a PAH-like compound (beta-naphthoflavone, BNF) followed by a heavy metal (chromium, Cr), focusing on the assessment of oxidative stress responses and their role in induction of genotoxicity. Oxidative stress responses in gill and kidney were investigated in European eel (Anguilla anguilla L.), and measured as lipid peroxidation (LPO), glutathione peroxidase (GPX), catalase (CAT) and glutathione S-transferase (GST) activity, and reduced glutathione (GSH) concentration, whereas genotoxicity was measured as DNA strand breakage. Fish were exposed for 24 h to two Cr concentrations (100 microM, 1 mM), with or without pre-exposure to BNF (2.7 microM, 24 h). In gill, a GSH decrease was observed along with loss of DNA integrity at all exposure conditions except at the lowest Cr concentration, showing a crucial role of GSH over genotoxicity. Moreover, sporadic induction of antioxidant enzymes was not effective in the protection against genotoxicity. However, a different mechanism seems to occur in kidney, since the loss of DNA integrity detected for all exposed groups was not accompanied by alterations in antioxidant levels. With regards to peroxidative damage, both organs showed an LPO increase after sequential exposure to BNF and 100 microM Cr. However, no association between LPO induction and antioxidant responses could be established, showing that LPO is not predictable solely on the basis of antioxidant depletion. The interference of BNF pre-exposure with the response of organs to Cr showed a marked dependence on the Cr concentration. Gill showed synergistic effects on LPO and GPX increase, as well as on CAT and GSH decrease for the lowest Cr concentration. However, for the highest concentration an additive effect on decrease of DNA integrity and an antagonistic effect on the increase of GPX were observed. In kidney, synergistic effects were evident on LPO increase and GSH decrease for the lowest Cr concentration, as well as on CAT and GST decrease for the highest concentration. In contrast, an antagonistic action was observed on DNA integrity loss for both Cr concentrations. The current results are relevant in assessing the interactions of PAHs and metals and contribute to a better knowledge about oxidative stress and mechanisms of genotoxicity in fish.     

Melatonin reduces oxidative stress induced by ochratoxin A in rat liver and kidney

Melatonin (MEL) displays antioxidant and free radical scavenger properties. In the present study, the effect of MEL on the oxidative stress induced by ochratoxin A (OTA) administration in rats was investigated. Four groups of 15 rats each were used: controls, MEL-treated rats (5 mg/kg body mass), OTA-treated rats (250 μg/kg) and MEL+OTA-treated rats. After 4 weeks of treatment, the levels of malondialdehyde (MDA), a lipid peroxidation product (LPO) were measured in serum and homogenates of liver and kidney. Also, the levels of glutathione (GSH), and activities of glutathione reductase (GR), glutathione peroxidase (GSPx), superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST) in liver and kidney were determined. In OTA-treated rats, the levels of LPO in serum and in both liver and kidney were significantly increased compared to levels in controls. Concomitantly, the levels of GSH and enzyme activities of SOD, CAT, GSPx and GR in both liver and kidney were significantly decreased in comparison with controls. In rats received MEL+OTA, the changes in the levels of LPO in serum and in liver and kidney were not statistically significant compared to controls. Concomitantly, the levels of GSPx, GR and GST activities in both liver and kidney tissues were significantly increased in comparison with controls. Similar increases in GSPx, GR and GST activities were also observed in MEL-treated rats when compared with controls. In conclusion, the oxidative stress may be a major mechanism for the toxicity of OTA. MEL has a protective effect against OTA toxicity through an inhibition of the oxidative damage and stimulation of GST activities. Thus, clinical application of melatonin as therapy should be considered in cases of ochratoxicosis.     

Glutathione and GSH-dependent enzymes in patients with liver cirrhosis and hepatocellular carcinoma

We investigated glutathione level, activities of selenium independent GSH peroxidase, selenium dependent GSH peroxidase, GSH S-transferase, GSH reductase and the rate of lipid peroxidation expressed as the level of malondialdehyde in liver tissues obtained from patients diagnosed with cirrhosis or hepatocellular carcinoma. GSH level was found to be lower in malignant tissues compared to adjacent normal tissues and it was higher in cancer than in cirrhotic tissue. Non-Se-GSH-Px activity was lower in cancer tissue compared with adjacent normal liver or cirrhotic tissue, while Se-GSH-Px activity in cancer was found to be similar to its activity in cirrhotic tissue and lower compared to control tissue. An increase in GST activity was observed in cirrhotic tissue compared with cancer tissue, whereas the GST activity in cancer was lower than in adjacent normal tissue. The activity of GSH-R was similar in cirrhotic and cancer tissues, but higher in cancer tissue compared to control liver tissue. An increased level of MDA was found in cancer tissue in comparison with control tissue, besides its level was higher in cancer tissue than in cirrhotic tissue. Our results show that the antioxidant system of cirrhosis and hepatocellular carcinoma is severely impaired. This is associated with changes of glutathione level and activities of GSH-dependent enzymes in liver tissue. GSH and enzymes cooperating with it are important factors in the process of liver diseases development.     

Accumulation and oxidative stress biomarkers in Japanese flounder larvae and juveniles under chronic cadmium exposure

This study investigated how Cd exposure affected oxidative biomarkers in Japanese flounder, Paralichthys olivaceus, at early life stages (ELS). Fish were exposed to waterborne Cd (0–48 µg L^− 1) from embryonic to juvenile stages for 80 days. Growth, Cd accumulation, activities of superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), glutathione S-transferase (GST, EC 2.5.1.18), and levels of glutathione (GSH) and lipid peroxidation (LPO) were investigated at three developmental stages. Flounder growth decreased and Cd accumulation increased with increasing Cd concentration. In metamorphosing larvae, CAT and SOD activities were inhibited and GSH level was elevated, while LPO was enhanced by increasing Cd concentrations. CAT and GST activities of settling larvae were inhibited but GSH level was elevated at high Cd concentrations. In juveniles, SOD activity and LPO level were increased but GST activity was inhibited as Cd concentration increased. Antioxidants in flounder at ELS were able to develop ductile responses to defend against oxidative stress, but LPO fatally occurred due to Cd exposure. These biochemical parameters could be used as effective oxidative biomarkers for evaluating Cd contamination and toxicity in marine environments: CAT, SOD, GSH, and LPO for metamorphosing stage; CAT, GSH, and GST for settling stage; and SOD, GST, and LPO for juvenile stage.     

N‐nitrosodimethylamine changes the expression of glutathione S‐transferase in the liver of male mice: The role of antioxidants

The present study investigated the protective effect of gossypol, selenium, zinc, or glutathione (GSH) against dimethylnitrosamine (DMN)‐induced hepatotoxicity in the livers of male mice. The expression and the activity of glutathione S‐transferase (GST), levels of GSH, and free radicals (malondialdehyde (MDA)), as well as the activity of glutathione reductase were determined after the treatment of mice for seven consecutive days with low or high doses of gossypol, selenium, zinc, or GSH. In experimental groups, DMN was administered as a single dose for 2 h after the repeated dose treatments of mice for seven consecutive days with each antioxidant. DMN reduced the expression and inhibited the activity of GST. However, repeated treatments of mice with low‐dose gossypol or high dose of either selenium or GSH followed by a single dose of DMN induced the expression and the activity of GST. In contrast, low‐dose treatments of mice with zinc, selenium, or GSH followed by a single dose of DMN reduced the expression and the activity of GST compared to either control or DMN‐treated groups. In addition, high‐dose treatment with either gossypol or selenium markedly induced the levels of GSH compared to either control or DMN‐treated groups. Interestingly, pretreatment of mice with high dose of either gossypol or selenium for seven consecutive days followed by a single dose of DMN decreased the levels of MDA, whereas DMN induced such levels. It is concluded that high dose of either gossypol or selenium is a stronger protector than zinc and GSH in ameliorating the toxic effects of DMN. © 2008 Wiley Periodicals, Inc. J Biochem Mol Toxicol 22:389–395, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jbt.20255     

Investigation of lipid peroxide and glutathione redox status of chicken concerning on high dietary selenium intake

This study was designed to investigate the effects of excess (24.5 mg Se/kg feed) inorganic and organic dietary selenium supplementation on 3-week-old broilers. The experiments lasted 4 days. Intensity of lipid peroxidation processes (malondialdehyde, MDA) and the amount (reduced glutathione, GSH) and activity (glutathione peroxidase activity, GSHPx) of gluathione redox system were measured in blood plasma, red blood cell hemolysate and liver. Voluntary feed intake in the selenium-treated groups reduced remarkably. Elevated GSH concentration and GSHPx activity were measured in plasma and liver of both selenium-treated groups compared to the untreated control and the 'pair-fed' controls. The lipid peroxidation processes in the liver showed higher intensity than the control due to both selenium treatment. The applied dose of selenite and selenomethionine does not inhibit, but even improves the activity of glutathione redox system in the liver during the early period of selenium exposure.     

Does mercury promote lipid peroxidation?

In order to explore the observed association among mercury, atherosclerosis, and coronary heart disease, the effects of mercury, copper, and iron on the peroxidation of low-density lipoprotein (LDL) and on the enzymatic activities of glutathione peroxidase and myeloperoxidase were investigated in vitro. On the basis of our nuclear magnetic resonance (NMR) experiments, we conclude that mercury does not promote the direct nonenzymatic peroxidation of LDL, like copper and iron. In our enzyme measurements, mercury inhibited slightly myeloperoxidase, although not significantly in presence of LDL. Instead, inorganic mercury, but not methylmercury chloride, inhibited glutathione peroxidase effectively and copper event at 10 μmol/L, below physiological concentrations, doubled the inhibition rate. Copper and iron had no direct effect on glutathione peroxidase, but they both seem to activate production of HOCl by myeloperoxidase. We conclude here that, first, mercury and methylmercury do not promote direct lipid peroxidation, but that, second, a simultaneous exposure to high inorganic mercury, copper, and iron and low selenium concentrations can lead to a condition in which mercury promotes lipid peroxidations. This mechanism provides a plausible molecular-level explanation for the observed association between high body mercury content and atherosclerosis.     

Selenium Pretreatment Upregulates the Antioxidant Defense and Methylglyoxal Detoxification System and Confers Enhanced Tolerance to Drought Stress in Rapeseed Seedlings

In order to observe the possible regulatory role of selenium (Se) in relation to the changes in ascorbate (AsA) glutathione (GSH) levels and to the activities of antioxidant and glyoxalase pathway enzymes, rapeseed (Brassica napus) seedlings were grown in Petri dishes. A set of 10-day-old seedlings was pretreated with 25 μM Se (Sodium selenate) for 48 h. Two levels of drought stress (10% and 20% PEG) were imposed separately as well as on Se-pretreated seedlings, which were grown for another 48 h. Drought stress, at any level, caused a significant increase in GSH and glutathione disulfide (GSSG) content; however, the AsA content increased only under mild stress. The activity of ascorbate peroxidase (APX) was not affected by drought stress. The monodehydroascorbate reductase (MDHAR) and glutathione reductase (GR) activity increased only under mild stress (10% PEG). The activity of dehydroascorbate reductase (DHAR), glutathione S-transferase (GST), glutathione peroxidase (GPX), and glyoxalase I (Gly I) activity significantly increased under any level of drought stress, while catalase (CAT) and glyoxalase II (Gly II) activity decreased. A sharp increase in hydrogen peroxide (H₂O₂) and lipid peroxidation (MDA content) was induced by drought stress. On the other hand, Se-pretreated seedlings exposed to drought stress showed a rise in AsA and GSH content, maintained a high GSH/GSSG ratio, and evidenced increased activities of APX, DHAR, MDHAR, GR, GST, GPX, CAT, Gly I, and Gly II as compared with the drought-stressed plants without Se. These seedlings showed a concomitant decrease in GSSG content, H₂O₂, and the level of lipid peroxidation. The results indicate that the exogenous application of Se increased the tolerance of the plants to drought-induced oxidative damage by enhancing their antioxidant defense and methylglyoxal detoxification systems.     

The effects of selenium on oxidative stress biomarkers in the freshwater characid fish matrinxã, Brycon cephalus (Günther, 1869) exposed to organophosphate insecticide Folisuper 600 BR (methyl parathion)

Methyl parathion (MP), an organophosphate widely applied in agriculture and aquaculture, induces oxidative stress due to free radical generation and changes in the antioxidant defense system. The antioxidant roles of selenium (Se) were evaluated in Brycon cephalus exposed to 2 mg L(-1) of Folisuper 600 BR (MP commercial formulation - MPc, 600 g L(-1)) for 96 h. Catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), glutathione S-transferase (GST), reduced glutathione (GSH) and lipid peroxidation (LPO) levels in the gills, white muscle and liver were evaluated in fish fed on diets containing 0 or 1.5 mg Se kg(-1) for 8 weeks. In fish treated with a Se-free diet, the MPc exposure increased SOD and CAT activities in all tissues. However, the GPx activity decreased in white muscle and gills whereas no alterations were observed in the liver. MPc also increased GST activity in all tissues with a concurrent decrease in GSH levels. LPO values increased in white muscle and gills and did not change in liver after MPc exposure. A Se-supplemented diet reversed these findings, preventing increases in LPO levels and concurrent decreases in GPx activity in gills and white muscle. Similarly, GSH levels were maintained in all tissue after MPc exposure. These results suggest that dietary Se supplementation protects cells against MPc-induced oxidative stress.     

Antioxidant response and oxidative stress levels in Macrobrachium borellii (Crustacea: Palaemonidae) exposed to the water-soluble fraction of petroleum

The aim of the present work was to evaluate the effect of the water soluble fraction of hydrocarbons (WSF) on the antioxidant status of the freshwater prawn Macrobrachium borellii. First, seasonal variations were studied in a non-polluted area. Hepatopancreas and gills showed season-related fluctuations in catalase (CAT), glutathione-S-transferase (GST) activities and in lipid peroxidation levels (LPO), but not in superoxide dismutase (SOD). Then, adults were exposed semi-statically to sublethal doses for 7days. CAT, SOD, GST, and glutathione peroxidase (GPx) activities and LPO, reduced glutathione (GSH) and protein oxidation (PO) levels were determined. Exposed individuals showed significant increases in CAT, SOD, and GST activities in hepatopancreas and CAT activity in gills. GPx activity did not vary in either tissues. While LPO levels increased, GSH levels decreased significantly in hepatopancreas of exposed animals, but PO levels showed no variation. Induction of SOD was also assessed by Real-time PCR mRNA expression in hepatopancreas. The non-enzymatic antioxidant activity was also tested; ABTS 2,2'-azino-bis(3-ethyl-benzothiazoline-6-sulfonic acid) was higher in hemolymph of treated-prawns compared to controls, but ferric reducing activity of plasma assay (FRAP) values did not change. Taken together, the present results indicated that the antioxidant defenses of M. borellii, mainly in hepatopancreas, were significantly affected by aquatic hydrocarbon contamination, regardless of the season.     

Oxidative DNA damage induced by iron chloride in the larvae of the lace coral Pocillopora damicornis

Biochemical and molecular biomarkers tools are utilized as early warning signatures of contaminant exposure to target and non-target organisms. The objective of this study was to investigate the sublethal effects of iron chloride to the larvae of the lace coral Pocillopora damicornis by measuring a suit of oxidative-stress biomarkers. The larvae were exposed to a range of sublethal concentrations of iron chloride (0.01, 0.1, 1, 10, and 100 ppm) for seven days. With reference to oxidative stress biomarkers, the no-observed effect concentration (NOEC) and the lowest observed effect concentration (LOEC) of iron chloride were observed to be 0.01 and 100 ppm respectively. At the end of the seventh day the antioxidant status of the larvae was evaluated by the levels of glutathione (GSH), glutathione peroxidase (GPX), glutathione reductase (GR), and glutathione-S-transferase (GST), in both experimental and control groups. For the quantification of cellular oxidative damage, lipid peroxidation (LPO) activity was determined in the same and the extent of DNA damage was assessed by the expression of DNA apurinic/apyrimidinic (AP) sites. Iron chloride exhibited a concentration-dependent inhibition of GSH and GPX and induction of GR, GST, LPO, and DNA-AP sites in the P. damicornis larvae when compared to the control group. The oxidative stress biomarkers of the larvae exposed to 0.1, 1, and 10 ppm of iron chloride did not show any significant overall differences when compared to the control group. However the activities of LPO, GSH, GPX, GR, GST and DNA-AP in the larval group exposed to 100 ppm of iron chloride exhibited statistically significant (P=0.002, 0.003, 0.002, 0.002, 0.005 and 0.007) differences when compared to the control group. The research results indicated that iron chloride in concentrations at the 100 ppm level caused oxidative stress in the P. damicornis larvae.     

Liver cancer is induced by a subnecrogenic dose of DENA when associated with fasting/refeeding: role of glutathione-transferase and lipid peroxidation.

In previous studies, we reported that fasting/refeeding has a role in sustaining the initiation of liver cancer by a subnecrogenic (noninitiating) dose of diethylnitrosamine (DENA). This research investigated whether the metabolic alterations imposed by fasting/refeeding provide an imbalance between the generation of carcinogenic molecules and the scavenger defense mechanisms in rat liver. Metabolism of DENA, levels of reduced glutathione (GSH) and GSH transferase (GST) activity, as well as basal and stimulated malondialdehyde (MDA) production, were examined. Rats fasted for 4 days showed a decrease in the liver levels of GSH, GST activity, monounsaturated fatty acids and % of labeled nuclei. After 1 day of refeeding, at which point DENA was administered, the levels of GSH recovered, GST activity remained below control values, basal and stimulated MDA production and content of total polyunsaturated fatty acids in liver phospholipids decreased. One day after DENA treatment, MDA production further decreased, although the % of labeled nuclei increased. No significant changes in the content of arachidonic acid, the main target of peroxidation, were observed at any time. The results indicated that the induction of the hepatocellular carcinoma was associated with a depression of GST activity and lipid peroxidation when rats were given 20 mg/kg of DENA after 1 day of refeeding after 4-day fasting.     

Glutathione-deficient state of nervous tissues in starved animals intensifies lipid peroxidation and oxidation of protein SH-groups

The levels of the lipid peroxidation products (LPO), different forms of protein SH-groups and their oxidation rate in the homogenates of the mesencephalon, hypothalamus and sensorymotor cortex of normal and GSH-deficient rats under 3-day food starvation were studied. It was shown, that the basic level of LPO products--lipid hydroperoxides and malonic dialdehyde (MDA) in hypothalamus and sensorymotor cortex of normal animals are by 20-30% (p < 0.05) higher and reduced glutathione (GSH) content is 2 times higher, than these values in mesencephalon. Under 3 day starvation of normal animals activation of the LPO observed only in the hypothalamus and sensorymotor cortex, whereas under 3 day starvation of the GSH-deficient rats formed by the intraparenteraly injection of diethylmaleate in a dose of 2.5 mmol/kg of body weight in all investigated structures the lipid hydroperoxides and MDA increased many times (2-3 times), the content of the surface and masked protein SH-groups decreased and essentially increased the oxidation rate of these functional groups. It was proposed that GSH and its enzymes participate in the LPO regulation and protection of protein SH-groups from oxidative damage at this event the intensity of this prosesse depends on structural and functional organization of nervous tissues.     

Antioxidant and lipid peroxidation responses in Mytilus galloprovincialis exposed to mixtures of benzo(a)pyrene and copper

This study aimed to assess the antioxidant system potential and lipid peroxidative effects, in the gill and digestive gland of Mytilus galloprovincialis exposed to individual and binary mixtures of benzo(a)pyrene (BaP) and Cu for 7 days. Data demonstrated that in mussels exposed to BaP antioxidant enzymes (catalase--CAT, total glutathione peroxidase--tGPx, glutathione S-transferase--GST and glutathione reductase--GR) and lipid peroxidation (LPO) increased in the gill. On the contrary, in the digestive gland inhibitory antioxidant effects (superoxide dismutase-SOD, GR, metallothioneins-MT) and no changes in LPO levels were detected. Cu was also a potent oxidant agent since MT and LPO levels increased in mussel gill, despite no LPO effect in the digestive gland. For both single contaminants the organ specificity and distinct physiologic/metabolism roles were evident in terms of antioxidant capacity. Gill SOD inhibition, MT and GST unchanged was a result of "simple independent action" of exposure to BaP and Cu. "Interactions" in the binary mixtures, led to absence of changes in LPO effects. In the digestive gland, BaP and Cu interactions were also responsible for the GST and LPO enhancement (antagonistic effects). The current findings demonstrate the differences in antioxidant responses where the organ dependency highlights each contaminant particular mode of action. Generally, in the gill "non-interactive" effects occurred with the lowest Cu concentration while "interactions" exist for the mixture with the highest Cu concentrations. In the digestive gland, "interactions" and "no interaction" effects occurred in all the binary mixtures. Complex contaminant mixtures interact differently based on target tissue which may lead to an imbalance in the mussels health status.     

Acorus calamus extracts and nickel chloride: prevention of oxidative damage and hyperproliferation response in rat kidney

Nickel, a major environmental pollutant, is known for its clastogenic, toxic, and carcinogenic potential. In this article, we report the effect of Acorus calamus on nickel chloride (NiCl2)-induced renal oxidative stress, toxicity, and cell proliferation response in male Wistar rats. NiCl2 (250 micromol/kg body weight/mL) enhanced reduced renal glutathione content (GSH), glutathione- S-transferase (GST), glutathione reductase (GR), lipid peroxidation (LPO), H2O2 generation, blood urea nitrogen (BUN), and serum creatinine with a concomitant decrease in the activity of glutathione peroxidase (GPx) (p < 0.001). NiCl2 administration also dose-dependently induced the renal ornithine decarboxylase (ODC) activity several-fold as compared to salinetreated control rats. Similarly, renal DNA synthesis, which is measured in terms of [3H] thymidine incorporation in DNA, was elevated following NiCl2 treatment. Prophylactic treatment of rats with A. calamus (100 and 200 mg/kg body weight po) daily for 1 wk resulted in the diminution of NiCl2- mediated damage, as evident from the downregulation of glutathione content, GST, GR, LPO, H2O2 generation, BUN, serum creatinine, DNA synthesis (p < 0.001), and ODC activity (p < 0.01) with concomitant restoration of GPx activity. These results clearly demonstrate the role of oxidative stress and its relation to renal disfunctioning and suggest a protective effect of A. calamus on NiCl2-induced nephrotoxicity in a rat experimental model.     

Aortic-banding induces myocardial oxidative stress and changes in concentration and activity of antioxidants in male Wistar rats

Myocardial activity and gene expression of antioxidant defenses and oxidative damage were examined in an experimental model of pressure overload hypertrophy. Male Wistar rats were divided into abdominal aortic-banded or sham-operated groups. After 30 days, arterial pressure and heart rate were measured. Heart, lung, and liver were extracted and weighted to evaluate cardiac hypertrophy and pulmonary and hepatic congestion. Heart homogenates were prepared to quantify lipid peroxidation (LPO); the activities of superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), glutathione peroxidase (GPx) and glutathione reductase (GR); and Cu-Zn SOD and GST concentrations. Total glutathione (GSH) myocardial content was also measured. Arterial pressure (142 +/- 17 mmHg) and cardiac hypertrophy index (3.4 +/- 0.45 mg/g) were significantly increased (by 38% and 22%, respectively, p<0.0001) in the aortic-banded group. LPO was enhanced by 55% in the aortic-banded group (11891 +/- 766 cps/mg protein, p<0.001) compared with that in the controls. SOD activity and concentration were higher (40% and 38%, 15.15 +/- 1.03 U/mg protein, 49.187 pixels, respectively, p<0.05) in the aortic-banded group than in the controls. Aortic-banding induced a decrease by 28% in GST (48 +/- 10 pmol/min/mg protein, p<0.005), by 36% in GPx (38.2 +/- 9.5 nmol/min/mg protein, p<0.005), by 31% in GR activities (1.55 +/- 0.23 nmol/mg protein, p<0.0005), and by 43% in GSH content (0.13 +/- 0.02 nmol/mg protein, p<0.005). In conclusion, in this model it was observed that myocardial oxidative stress induces alterations in antioxidant enzyme activities and protein expression. The follow up of these parameters could afford an early therapeutical window to avoid heart failure progression.     

Glutathione metabolism in Urtica dioica in response to cadmium based oxidative stress

To investigate the antioxidative response of glutathione metabolism in Urtica dioica L. to a cadmium induced oxidative stress, activities of glutathione reductase (GR), glutathione-S-transferase (GST), and glutathione peroxidase (GSH-Px), content of reduced (GSH) and oxidized (GSSG) glutathione, lipid peroxidation (LPO), and also accumulation of Fe, Zn, Mn, Cu besides Cd were determined in the roots, stems, and leaves of plants exposed to 0 (control), 0.045, and 0.09 mM CdCl₂ for 58 h. Whereas the Cd content continuously increased in all organs, the Fe, Zn, Mn, and Cu content decreased in dependence on the applied Cd concentration and incubation time. The Cd treatment resulted in increased GR and GST activities in all organs, however, GSH-Px activity was dependent on Cd concentration and plant organ. The GSH/GSSG ratio maintained above the control level in the stems at both Cd concentrations. The LPO was generally close to the control values in the roots and stems but it increased in the leaves especially at 0.09 mM Cd.     

Selenium-Induced Up-Regulation of the Antioxidant Defense and Methylglyoxal Detoxification System Reduces Salinity-Induced Damage in Rapeseed Seedlings

The present study investigates the regulatory role of exogenous selenium (Se) in the antioxidant defense and methylglyoxal (MG) detoxification systems in rapeseed seedlings exposed to salt stress. Twelve-day-old seedlings, grown in Petri dishes, were supplemented with selenium (25 μM Na₂SeO₄) and salt (100 and 200 mM NaCl) separately and in combination, and further grown for 48 h. The ascorbate (AsA) content of the seedlings decreased significantly with increased salt stress. The amount of reduced glutathione (GSH) and glutathione disulfide (GSSG) increased with an increase in the level of salt stress, while the GSH/GSSG ratio decreased. In addition, the ascorbate peroxidase (APX) and glutathione S-transferase (GST) activity increased significantly with increased salt concentration (both at 100 and 200 mM NaCl), while glutathione peroxidase (GPX) activity increased only at moderate salt stress (100 mM NaCl). Glutathione reductase (GR) activity remained unchanged at 100 mM NaCl, while it was decreased under severe (200 mM NaCl) salt stress. Monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), catalase (CAT), glyoxalase I (Gly I), and glyoxalase II (Gly II) activities decreased upon the imposition of salt stress, whereas a sharp decrease of these activities was observed under severe salt stress (200 mM NaCl). Concomitant increases in the levels of H₂O₂ and lipid peroxidation (MDA) were also measured. Exogenous Se treatment alone had little effect on the non-enzymatic and enzymatic components. However, further investigation revealed that Se treatment had a synergistic effect: in salt-stressed seedlings, it increased the AsA and GSH contents; GSH/GSSG ratio; and the activities of APX, MDHAR, DHAR, GR, GST, GPX, CAT, Gly I, and Gly II. As a result, addition of Se in salt-stressed seedlings led to a reduction in the levels of H₂O₂ and MDA as compared to salt stress alone. These results suggest that the exogenous application of Se rendered the plants more tolerant to salt stress-induced oxidative damage by enhancing their antioxidant defense and MG detoxification systems.