Ethanol-induced alterations of the antioxidant defense system in rat kidney

We report here the effects of chronic ethanol consumption on the antioxidant defense system in rat kidney. Thirty-two male Wistar rats were randomly divided in two identical groups and were treated as follows: control group (water for fluid) and the ethanol-fed group (2 g/kg body weight/24 h). The animals were sacrificed after 10 weeks, and respectively 30 weeks of ethanol consumption, and the renal tissue was isolated and analyzed. Results revealed that kidney alcohol dehydrogenase activities increased significantly after ethanol administration, but the electrophoretic pattern of alcohol dehydrogenase isoforms was unmodified. The SDS polyacrylamidegel electrophoretic study of kidney proteins has revealed the appearance of two new protein bands after long-term ethanol consumption. The kidney reduced glutathione/oxidized glutathione ratio decreased, indicating an oxidative stress response due to ethanol ingestion. The malondialdehyde contents and xanthine oxidase activities were unchanged. The antioxidant enzymatic defense system showed a different response during the two periods of ethanol administration. After 10 weeks, catalase, glutathione peroxidase, glutathione reductase, and glucose-6-phosphate dehydrogenase were activated, while superoxide dismutase, glutathione transferase, and gamma-glutamyltranspeptidase levels were stationary. After 30 weeks, superoxide dismutase and glutathione peroxidase activities were unmodified, but catalase, glutathione transferase, gamma-glutamyltranspeptidase, glutathione reductase, and glucose-6-phosphate dehydrogenase activities were significantly increased. Remarkable changes have been registered after 30 weeks of ethanol administration for glutathione reductase and glucose-6-phosphate dehydrogenase activities, including an increase by 106 and 216' of control values, respectively. These results showed specific changes in rat kidney antioxidant system and glutathione status as a consequence of long-term ethanol administration.     

Ethanol‐induced alterations of the antioxidant defense system in rat kidney

We report here the effects of chronic ethanol consumption on the antioxidant defense system in rat kidney. Thirty‐two male Wistar rats were randomly divided in two identical groups and were treated as follows: control group (water for fluid) and the ethanol‐fed group (2 g/kg body weight/24 h). The animals were sacrificed after 10 weeks, and respectively 30 weeks of ethanol consumption, and the renal tissue was isolated and analyzed. Results revealed that kidney alcohol dehydrogenase activities increased significantly after ethanol administration, but the electrophoretic pattern of alcohol dehydrogenase isoforms was unmodified. The SDS polyacrylamidegel electrophoretic study of kidney proteins has revealed the appearance of two new protein bands after long‐term ethanol consumption. The kidney reduced glutathione/oxidized glutathione ratio decreased, indicating an oxidative stress response due to ethanol ingestion. The malondialdehyde contents and xanthine oxidase activities were unchanged. The antioxidant enzymatic defense system showed a different response during the two periods of ethanol administration. After 10 weeks, catalase, glutathione peroxidase, glutathione reductase, and glucose‐6‐phosphate dehydrogenase were activated, while superoxide dismutase, glutathione transferase, and γ‐glutamyltranspeptidase levels were stationary. After 30 weeks, superoxide dismutase and glutathione peroxidase activities were unmodified, but catalase, glutathione transferase, γ‐glutamyltranspeptidase, glutathione reductase, and glucose‐6‐phosphate dehydrogenase activities were significantly increased. Remarkable changes have been registered after 30 weeks of ethanol administration for glutathione reductase and glucose‐6‐phosphate dehydrogenase activities, including an increase by 106 and 216' of control values, respectively. These results showed specific changes in rat kidney antioxidant system and glutathione status as a consequence of long‐term ethanol administration. © 2005 Wiley Periodicals, Inc. J Biochem Mol Toxicol 19:386‐395, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jbt.20101     

Immobilization stress in rat tissues: alterations in protein oxidation, lipid peroxidation and antioxidant defense system

We determined the effects of immobilization stress on antioxidant status, protein oxidation and lipid peroxidation in brain, liver, kidney, heart and stomach of rats. Sixteen male Wistar rats (3 months old) were divided into controls (C) and immobilization stress group (IS). IS rats were immobilized for 180 min/day for 15 days. Plasma corticosterone levels were increased in IS group. Copper,zinc-superoxide dismutase activities were increased in brain, liver and kidney, but decreased in the heart and stomach after immobilization. Catalase activities were increased in brain, kidney and heart, and decreased in liver and stomach. Selenium-dependent glutathione peroxidase activities were decreased in brain and kidney, but increased in heart and stomach. Reduced glutathione levels were decreased, while protein carbonyl, conjugated dienes and thiobarbituric acid-reactive substances levels were increased in all tissues. Our results showed that the response of antioxidant defense system to stress differs for each tissue, and protein oxidation and lipid peroxidation is induced by immobilization stress in peripheral tissues.     

Influence of dietary ginger (Zingiber officinales Rosc) on antioxidant defense system in rat: comparison with ascorbic acid

Ginger (Z. officinale; 1% w/w) significantly lowered lipid peroxidation by maintaining the activities of the antioxidant enzymes--superoxide dismutase, catalase and glutathione peroxidase in rats. The blood glutathione content was significantly increased in ginger fed rats. Similar effects were also observed after natural antioxidant ascorbic acid (100 mg/kg, body wt) treatment. The results indicate that ginger is comparatively as effective as ascorbic acid as an antioxidant.     

The daily dietary selenium intake of West German adults

The selenium content of food consumed in the Federal Republic of Germany (FRG) was determined for the estimation of the dietary selenium intake of West German adults. The daily dietary selenium intake of men is 47 micrograms (micrograms) and that of women 38 micrograms, corresponding to 0.67 microgram/kg body weight per day for both men and women. Animal protein is the main source of dietary selenium, accounting for 65.5% of the total selenium intake. Pork contributes 25.1% to the total Se intake, reflecting the current consumption and the selenium supplementation of feedstock rather than the availability of selenium from natural dietary sources. The selenium intake of adults in West Germany is only slightly higher than in New Zealand, Finland, and Italy, nearly equal to that in Belgium and France, and distinctly lower than in Great Britain, the USA, Canada, and Japan.     

Neuroprotective effects of zinc on antioxidant defense system in lithium treated rat brain

With a view to find out whether zinc affords protection against lithium toxicity the activities of antioxidant enzymes and lipid peroxidation profile were determined in the cerebrum and cerebellum of lithium treated female Sprague Dawley rats. Lipid peroxidation was significantly increased in both the cerebrum and the cerebellum of animals administered with lithium for a total duration of 4 months as compared to the normal control group. On the contrary, the activities of catalase and glutathione-s-transferase (GST) were significantly reduced after 4 months of lithium treatment. The activity of superoxide dismutase (SOD) was significantly increased in the cerebrum after 4 months lithium administration, whereas in the cerebellum the enzyme activity was unaffected. No significant change in the levels of reduced glutathione (GSH) was found in either cerebrum or cerebellum after 2 months of lithium treatment. However, 4 months lithium treatment did produce significant changes in GSH levels in the cerebrum and in the cerebellum. Zinc supplementation for 4 months in lithium-treated rats significantly increased the activities of catalase and GST in the cerebellum, showing that the treatment with zinc reversed the lithium induced depression in these enzyme activities. Though, zinc treatment tended to normalize the SOD activity in the cerebrum yet it was still significantly higher in comparison to normal levels. From the present study, it can be concluded that the antiperoxidative property of zinc is effective in reversing the oxidative stress induced by lithium toxicity in the rat brain.     

Effect of selenium on lead-induced alterations in rat brain

The effects of lead (Pb) and selenium (Se) interactions on central nervous system (CNS) functions were seen in adult rats by both biochemical and histologic pathological alterations. Pb administration of 20 mg/kg body wt for 8 wk showed degenerative changes only in the cerebral cortex. The changes in the cerebellar regions were not significant. Biochemically a marked decrease in the DNA, RNA, and protein content was seen following lead treatment. These decreases were significant in both the regions of the brain. During the concomitant administration of Pb and Se, the alterations in the transverse section of cerebral cortex showed only marginal changes. The values of DNA and RNA content showed significant improvement in both regions of the brain compared to the Pb treated group.     

Vitamin E and selenium administration as a modulator of antioxidant defense system: biochemical assessment and modification

Exposure of cells to ionizing radiation leads to the formation of reactive oxygen species (ROS) that are associated with radiation-induced cytotoxicity. Because of the serious damaging potential of ROS, cells depend on the elaboration of the antioxidant defense system (AODS), both enzymatic and nonenzymatic oxidant defense mechanisms. The deficiency in important components of the endogenous AODS leads to the accumulation of oxidative stress inducing oxidative damage. The antioxidant enzymes superoxide dismutase and glutathione peroxidase are key intracellular antioxidants in the metabolism of ROS. In the current study, we investigated the potential role of these antioxidant enzymes in radioresistance during the evaluation of the compensatory role of some exogenous micronutrients against oxidative stress Animals were categorized into eight groups, receiving vitamin E (α-tocopherol) and/or selenium (Se) with or without whole-body γ-irradiation (6.5 Gy). The results indicate that antioxidant pretreatments before irradiation may have some beneficial effects against irradiation-induced injury. The results also indicate that selenium and vitamin E act alone and in an additive fashion as radioprotecting agents. The results further suggest that selenium confers protection in part by inducing or activating cellular free-radical scavenging systems and by enhancing peroxide breakdown, whereas vitamin E appears to confer its protection by an alternate complementary mechanism.     

Determination of selenium in serum by FI-HG-AAS and calculation of dietary intake

A method was developed for the determination of selenium concentration in serum by flow injection-hydride generation-atomic absorption spectrometry (FI-HG-AAS) following microwave digestion of serum samples and reduction of selenate to selenite. The detection limit of the method was 0.3 μg Se/L and the characteristic concentration, corresponding to the 0.0044 absorbance signal, was 0.12 μg Se/L. The results from the analysis of two Seronorm standard reference materials showed good agreement with the certified values. The method was then used to analyze selenium in sera of Austrian and Slovenian people for the calculation of dietary intakes. The selenium concentrations in sera of mothers at delivery, their neonates, and the male and female adults were 71 ± 14, 42 ± 6, 75 ± 21, and 65 ± 16 μg/L for the Austrians and 62 ± 15, 34 ± 7, 70 ± 12, and 66 ± 15 μg/L for the Slovenians. The dietary intakes of selenium of the mothers and the male and the female adults were calculated as 52, 37, and 46 μg/d for the Austrians and 45, 38, and 32 μg/d for the Slovenians.     

Effect of chronic cadmium exposure on antioxidant defense system in some tissues of rats: protective effect of selenium

The effects of selenium (Se) on antioxidant defense system in liver and kidneys of rats with cadmium (Cd)-induced toxicity were examined. Cd exposure (15 mg Cd/kg b.m./day as CdCl(2) for 4 weeks) resulted in increased lipid peroxidation (LP) in both organs (p<0.005 and p<0.01). Vitamin C (Vit C) was decreased in the liver (p<0.005), whereas vitamin E (Vit E) was increased in the liver and kidneys (p<0.005 and p<0.05) of Cd-exposed animals. Superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were decreased in both tissues (p<0.05 and p<0.005), whereas catalase (CAT) activity was decreased only in liver (p<0.005). Glutathione S-transferase (GST) increased in both tissues (p<0.005 and p<0.01). Treatment with Se (0.5 mg Se/kg b.m./day as Na(2)SeO(3) for 4 weeks) significantly increased liver and kidneys SOD and GSH-Px activities (p<0.05 to p<0.005), as well as CAT and GST activities only in the liver (p<0.01). In animals exposed to Se, both the concentrations of Vit C (p<0.01) and Vit E (p<0.005) were increased in both tissues. Co-treatment with Se resulted in reversal of oxidative stress with significant decline in analyzed tissues Cd burden. Our results show that Se may ameliorate Cd-induced oxidative stress by decreasing LP and altering antioxidant defense system in rat liver and kidneys and that Se demonstrates the protective effect from cadmium-induced oxidative damage.     

Interaction between dietary selenium and 2-acetylaminofluorene in the rat

The effect of dietary selenium on the metabolism of 2-acetylaminofluorene (AAF) and on its interaction with hepatic DNA was studied in male, Charles River rats. All studies were commenced at least 3 weeks after placing weanling rats on a tomla yeastbased Se-deficient diet or the same diet supplemented with 0.5 ppm Se as Na₂SeO₃. Analysis of radioactive metabolites generated during in vitro incubation of [9-¹⁴C]-AAF with hepatic microsomes showed that Se-supplemented rats produced greater amounts of noncarcinogenic, phenolic metabolites than did Se-deficient animals. No significant difference was noted between the two dietary groups with respect to the production of the proximate carcinogenic metabolite,N-hydroxy-AAF. Analysis of urinary metabolites excreted during a 24-h period following a single ip injection of [9-¹⁴C]-AAF showed that Se-deficient animals produced 2–3 times as much N-hydroxy-AAF as did the supplemented rats. The increased excretion of the proximate carcinogenic metabolite by Se-deficient rats occurred both as the free and glucuronic acid conjugated forms. In contrast, Se-deficient rats excreted lower amounts of noncarcinogenic AAF metabolites. Taken together, these results suggest that dietary Se alters AAF biotransformation so as to decrease metabolic activation while enhancing detoxification pathways. The effect of dietary Se on AAF-DNA interactions was assessed in two ways. First, it was found that Se had no effect on the total amount of AAF residues covalently bound to hepatic DNA in vivo. This lack of effect was observed both at early (1-24 h) and late (4-7 d) intervals after administering a single ip injection of [9-¹⁴C]-AAF to rats from both dietary groups. In contrast, alkaline sucrose gradient analysis revealed a marked protective.effect of Se against AAF-induced DNA single-strand breaks. Further studies showed that the protective effect of Se was not mediated by a more rapid rate of repair of DNA damage. Accordingly, in addition to its favorable actions on carcinogen metabolism, the ability of Se to protect DNA against reactive metabolites may play a role in its reported anticarcinogenic activity.     

Sulphadoxine-pyrimethamine alters the antioxidant defense system in blood of rabbit

Sulphadoxine-pyrimethamine (SP) despite reported resistance remains an important drug of choice for the treatment and control of malaria in most endemic areas. Exacerbation of intra-erythrocytic oxidative stress might contribute to the process of elimination of malaria parasites in the body. The effect of treatment with SP on the antioxidant defense system was investigated using rabbit as a model. Ten male rabbits were divided into two groups of five animals each. The first group was administered with normal saline and served as control. The second group received a single dose of SP (26.25mg/kg body weight). Blood samples were collected before and at 6, 12 and 24 h after drug administration. Activity of cellular enzymatic antioxidants, superoxide dismutase (SOD) and catalase (CAT), and level of reduced glutathione (GSH) were assayed using standard spectrophotometric methods. Serum lipid peroxidation was assessed by the formation of thiobarbituric acid reactive species (TBARS) while protein content was assayed by the method of Lowry et al., 1951. SOD activity was observed to increase progressively by 4.9, 63.4 and 120.8% at 6, 12 and 24 h respectively, after drug administration. Similarly, CAT activity increased by 44.5, 82.6 and 116.3% at 6, 12 and 24 h, respectively. TBARS level also increased significantly by 45.5, 118.2 and 186.4%, respectively. However, the level of GSH decreased by 41.9% at 6 h and remained so up till the 12 h, but by 24 h after drug administration, the level of the thiol substance has increased considerably up to 48.4% above the baseline level. SP treatment altered the antioxidant defense system in blood and may therefore induce oxidative stress by generating reactive oxygen species. This might play significant role in the therapeutic and adverse effects associated with the drug.     

Effect of dietary selenium restriction on selected parameters of selenium status in men with high life-long intake

The influence of selenium (Se) restriction on disposition in plasma and urine fractions of infused (74)Se (selenite) was studied when adult males (Enshi City, Hubei Province, PRC) whose habitual daily Se intake is approximately 480 microg per day were transferred to Lichuan County, where the daily intake is approximately 30 microg. The subjects received an infusion (106 microg Se) on the day before consuming foods low in Se and a second infusion (113 microg Se) 63 days later. Blood and 24-hour urine samples were collected each day for 7 days after the first infusion and on days 22, 43, and 62 following the first infusion. Urine and blood were also collected daily for the next 7 days after the second infusion. Plasma total Se concentration increased for 7 days after each of the two infusions and urine Se decreased exponentially following both the first and second infusions. The excretion of trimethylselenonium followed the same pattern as the total urinary Se. Surprisingly, there was not a significant difference in selenite retention between the two infusion periods, and the data indicated that, regardless of the chemical form of Se present in various organs, its catabolism leading to excretion in urine followed the same pathway as that of selenite. Labeled Se was incorporated predominantly in the plasma selenoprotein P fraction and the half-life of Se in this fraction was determined to be 1.9 to 2.9 days. Thus, a longer depletion period is required in these subjects to obtain more significant changes.     

The glutathione-dependent system of placenta antioxidant defense in miscarriage

The glutathione-dependent system of antioxidant defense was studied in the chorionic and placental tissues of women with miscarriage. In the case of spontaneous abortion, the level of glutathione peroxidase reached the maximum even in trimester I and remained more than 1.5-fold higher during the whole gestation period than in the placental tissue of women with physiological pregnancy and delivery. The activity of glutathione reductase in miscarriage was insignificantly different from that in the control group. The activity of glutathione S-transferase in miscarriage was similar to that in the control group during trimester I and remained low during the whole gestation, contributing to a decrease in nonspecific defense in the mother-placenta-fetus system, leading to pathology of the fetus and infant. It is concluded that oxidative stress in the placental tissues is an essential pathogenic factor of miscarriage.     

The response of the antioxidant defense system in rat hepatocytes challenged with oxysterols is modified by Covi-ox

Suspension cultures of isolated rat hepatocytes were used to investigate whether 7-ketocholesterol and cholestane-3,5,6-triol exert oxidative stress in cells as manifested by increased lipid peroxidation and the induction of the antioxidant enzymes catalase, glutathione peroxidase and superoxide dismutase. The oxysterols were found to increase the levels of both superoxide dismutase and catalase and to have variable effects on glutathione peroxidase activity. Increased lipid peroxidation was not observed, indicating that the endogenous antioxidant defense system was capable of protecting against any oxidative stress that might otherwise by exerted by 7-ketocholesterol or cholestane-3,5,6-triol. Covi-ox, a natural tocopherol blend reduced the effects of both oxysterols on the antioxidant enzymes. A concurrent reduction in the production of thiobarbituric acid-reactive substances in Covi-ox-treated cells is indirect evidence that reactive oxygen species were produced by oxysterols in hepatocyte suspension cultures.     

Cadmium-induced alterations of the structural features of pectins in flax hypocotyl

In the course of our studies on the putative role of pectins in the control of cell growth, we have investigated the effect of cadmium on their composition, remodelling and distribution within the epidermis and fibre tissues of flax hypocotyl (Linum usitatissimum L.). Cadmium-stressed seedlings showed a significant inhibition of growth whereas the hypocotyl volume did not significantly change, due to the swelling of most tissues. The structural alterations consisted of significant increase of the thickness of all cell walls and the marked collapse of the sub-epidermal layer. The pectic epitopes recognized by the anti-PGA/RGI and JIM5 antibodies increased in the outer parts of the epidermis (external tangential wall and junctions) and fibres (primary wall and junctions). Concomitantly, there was a remarkable decrease of JIM7 antibody labelling and consequently an increase of the ratio JIM5/JIM7. Conversely, the ratio JIM7/JIM5 increased in the wall domains closest to the plasmalemma, which would expel the cadmium ions from the cytoplasm. The hydrolysis of cell walls revealed a cadmium-induced increase of uronic acid in the pectic matrix. Sequential extractions showed a remodelling of both homogalacturonan and rhamnogalacturonan I. In fractions enriched in primary walls, the main part of the pectins became cross-linked and could be extracted only with alkali. In fractions enriched in secondary walls, the homogalacturonan moieties were found more abundantly in the calcium-chelator extract while the rhamnogacturonan level increased in the boiling water extract.     

Ascorbate deficient semi-dwarf asfL1 mutant of Lathyrus sativus exhibits alterations in antioxidant defense

An ascorbate-deficient semi-dwarf mutant asfL-1 was detected in 250 Gy γ-ray treated grass pea (Lathyrus sativus L.) cv. BioR-231. The mutant contained only 42 % of leaf and 20 % of root ascorbate content of mother control (MC). I investigated the possible causes of ascorbate deficiency and its effect on growth and antioxidant defense in control and 150 mM NaCl-treated seedling after 60 d growth period. Ascorbate deficiency was due to significant reduction in activities of monodehydroascorbate reductase and dehydroascorbate reductase as well as increase in ascorbate oxidase, leading to considerable decrease in redox state. Despite low ascorbate pool and decrease in ascorbate peroxidase activity, shoot and root biomass production in asfL-1 mutant were similar to MC plants, even at NaCl treatment. High accumulation of glutathione (GSH) coupled with high activities of GSH reductase, catalase, GSH peroxidase and peroxidase in both tissues of the mutant permitted efficient recycling of GSH and scavenging of H₂O₂ through well integrated catalase/peroxidase system, despite high superoxide dismutase activity under NaCl treatment. The collapse of this system led to inhibition of growth in NaCl-treated mother plants. Together, the results suggested that asfL-1 plants undertook a major reshuffle in its antioxidant defense machinery, which effectively counterbalanced the negative impact of ascorbate deficiency and remained unperturbed by NaCl treatment to maintain normal growth and biomass production.