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PubMed2005

Expression of ascorbate peroxidase and glutathione reductase in roots of rice seedlings in response to NaCl and H2O2.

The accumulation of H2O2 by NaCl was observed in the roots of rice seedlings. Treatment with NaCl caused an increase in the activities of ascorbate peroxidase (APX) and glutathione reductase (GR) and the expression of OsAPX and OsGR in rice roots. Exogenously applied H2O2 also enhanced the activities of APX and GR and the expression of OsAPX and OsGR in rice roots. The accumulation of H2O2 in rice roots in response to NaCl was inhibited by the NADPH oxidase inhibitors, diphenyleneiodonium chloride (DPI) and imidazole (IMD). However, DPI, IMD, and dimethylthiourea, a H2O2 trap, did not reduce NaCl-enhanced activities of APX and GR and expression of OsAPX and OsGR. It appears that H2O2 is not involved in the regulation of NaCl-induced APX and GR activities and OsAPX and OsGR expression in rice roots.

Ascorbate Peroxidases↗
PubMed1989

Modulation of embryonic glutathione reductase and phenytoin teratogenicity by 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU).

The teratogenicity of phenytoin may be mediated through a reactive electrophilic and/or free radical intermediate which, if not detoxified, may interact with fetal cellular macromolecules and initiate teratologic effects. Glutathione (GSH) maintains cellular physiological processes and detoxifies xenobiotic reactive intermediates. The role of GSH in protection against phenytoin embryopathy was studied by altering GSH homeostasis using 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), an inhibitor of glutathione reductase. BCNU was administered to pregnant CD-1 mice on gestational day 12, in doses ranging from 10 to 50 mg/kg i.p., with or without phenytoin, 55 or 65 mg/kg i.p., given 4 and 24 hr after BCNU. BCNU alone in doses of 10, 25 or 50 mg/kg resulted in a dose-related increase in the incidence of resorptions, cleft palates and postpartum death (P less than .05), and in lowered fetal weight (P less than .05). Fetuses exposed to 50 mg/kg of BCNU had an array of gross abnormalities, and this dose was not used in subsequent studies. BCNU, 25 mg/kg, inhibited GSH reductase activity by 23% in the placenta (P less than .05) and by 30% in the embryo (P less than .05) at 4 hr after treatment. Embryonic, but not placental GSH reductase activity remained significantly inhibited at 24 hr after BCNU. A BCNU dose-related increase in the incidence of resorptions (P less than .0001) and postpartum death (P less than .05) was seen in groups treated with both BCNU and 65 mg/kg of phenytoin, compared to controls treated with either chemical alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2002

The capacity of glutathione reductase in cell protection from the toxic effect of heated oils.

This empirical study tries to focus on the evidence that the wrong use of oil in food cooking leads to health problems. High temperatures associated with the repeated use of the same oil lead to the breakdown of some fatty acids, forming numerous toxic polymer compounds and peroxides. The obtained data have showed that the ratios of polymer compounds reached 11.3% in oil heated continuously for 10 h at 220 degrees C, and 37.8% in frying oil (FO). Moreover, the polar compound ratios reached 25.6% and 47.6% in continuously heated oil (CHO) and FO, respectively. However, the peroxide concentrations were 157.1 and 133.6 mM/kg in CHOs and FOs, respectively. The observed results have allowed the study of the role of the glutathione redox system in the detoxification and elimination of different toxic peroxides resulting from heated oils. On a diet of 10% of CHO and FO, a significant increase in glutathione peroxidase (GPx) and glutathione reductase (GR) activities appears. This combined relationship between the decreased glutathione content and the increased GPx and GR activities in rats fed on CHO and FO confirms the participation of the glutathione redox system in the detoxifying reactions of continuously accumulated peroxides.

Animals↗
PubMed1976

Effect of simultaneous thiamin and riboflavin deficiencies on the determination of transketolase and glutathione reductase.

Thiamin and/or riboflavin status have been assessed in rats simultaneously deprived of both vitamins and subsequently repleated with either one or the other in succession. Undernutrition in control rats was found to depress the activity of the erythrocyte enzymes (transketolase and glutathione reductase, respectively) used to assess status. On the other hand, the activity coefficients obtained by in vitro stimulation of the enzymes with their respective missing cofactors were not suppressed. Therefore the activity coefficients were superior indices of thiamin and riboflavin nutriture compared to the enzyme activities. When activity coefficients were used as the indices of vitamin status there did not appear to be interference from the simultaneous deficiency of the alternate vitamin. Apparent interference was encountered when the enzyme activity itself was used as the criteria.

Animals↗
PubMed1997

[The effect of different high riboflavin supplements during pregnancy and lactation on performance and erythrocyte glutathione reductase activity of rats].

In two experiments with 160 female Sprague-Dawley rats the influence of various dietary riboflavin supplementations during lactation and during pregnancy and lactation were examined on food intake, body mass, reproduction, hematologic profile and the erythrocyte glutathione reductase activity coefficient (EGR-AC). In the first trial rats were fed a semisynthetic, riboflavin-deficient diet, based on casein and corn starch with various riboflavin supplementations during lactation (0, 2, 4, 6, 8, 10, 12, 40, 400, 4000 mg riboflavin/kg diet). In the second experiment the rats received supplements of 1 and 20 mg riboflavin/kg diet, respectively, during pregnancy. After parturition each group was divided into three sub-groups with riboflavin supplementations during lactation of 1, 5 and 20 mg/kg diet, respectively. Both investigations ended at the 14th day of lactation. Food intake was decreased significantly by 25% and 11% in the groups without riboflavin supplementation or 1 mg riboflavin/kg diet. In the same groups body mass was reduced by 11% and 4%, respectively. With regard to the reproduction parameters the riboflavin supply influenced only the litter mass at the 14th day of lactation and only lactational supply was relevant. In both trials the results of the hematologic profile showed no differences. In riboflavin deficiency (0 or 1 mg riboflavin/kg diet, respectively) the EGR-AC was increased significantly to 1.9 and 1.8, respectively. At the supplementation of 4-5 mg riboflavin/kg diet EGR-AC reached a plateau of 1.45, which was not improved by higher supplements. Concerning the whole reproduction cycle (trial II) there was a stronger influence of the actual lactation-supply on EGR-AC, on the other hand a riboflavin deficiency in pregnancy could be compensated only partially by an optimal supply in lactation. Therefore, based on the parameter EGR-AC an optimal riboflavin supply is recommended for each part of the reproduction cycle. By means of EGR-AC also the riboflavin requirement for lactating rats was derived. Feeding a semisynthetic diet (17.4 MJ ME/kg DM, 20.8% crude protein in DM) a supplementation of 5-6 mg riboflavin/kg or a total content of 6-7 mg/kg diet is recommended.

Animals↗
PubMedDate not supplied

Isolation and characterization of glutathione reductase from Physarum polycephalum and stage-specific expression of the enzyme in life-cycle stages with different oxidation-reduction levels.

Physarum polycephalum has a life cycle with several distinct phases that have different oxidation-reduction requirements. To investigate the relationship between the life cycle and the oxidation-reduction state, we isolated glutathione reductase (GR; EC 1.6.4.2) from Physarum microplasmodia. The enzyme was found to be a homodimer with a subunit M(r) of 49,000, and K(m) values for oxidized glutathione and NADPH of 40 and 28.6 microM, respectively. We then constructed a cDNA library from microplasmodium mRNA and cloned GR cDNA from the library. The isolated cDNA consisted of 1,475 bp encoding a polypeptide of 452 amino acids. The amino acid sequence similarity was about 50% with GRs of other organisms, and several conserved sequence motifs thought to be necessary for activity are evident in the Physarum enzyme. Escherichia coli transformed with an expression vector containing the cDNA synthesized the active GR. Genomic Southern blot analysis indicated that the GR gene is present as a single copy in the Physarum genome. Immunoblot analysis and RT-PCR analysis detected GR mRNA expression in the microplasmodium, plasmodium, and sclerotium, but not in the spore or flagellate. GR activity was low in the spore and flagellate. These results suggest that the glutathione oxidation-reduction system relates to the Physarum life cycle.

Amino Acid Sequence↗
PubMed1990

Antimalarial action of flavin analogues seems not be due to inhibition of glutathione reductase of host erythrocytes.

A series of 10-(4'-chlorophenyl)-3-substituted flavins (1a-f) were examined with respect to their antimalarial properties. They were tested against Plasmodium falciparum in vitro and Plasmodium vinckei vinckei in vivo. The proposition that they might act through glutathione reductase (GR) (EC 1.6.4.2) inhibition has been studied. Inhibition of P. falciparum in vitro by these compounds shows only slight variation between analogues; in contrast, inhibition of human erythrocyte GR by members of the same series is highly variable, indicating that this is probably not their primary mode of antimalarial action. Results of the P. vinckei vinckei screen showed that 10-(4'-chlorophenyl)-3-methyl,3-ethyl and 3-propyl substituted flavins are active in vivo over the dose range screened (10-70 mg/kg).

Animals↗
PubMed1977

Effects of hyperoxia on glutathione reductase activity, membrane proteins, and esterases of rabbit erythrocytes.

Rabbits were exposed to 100% oxygen at pressures of 256 to 1520 mm Hg for up to 5 d and the blood and erythrocytes of these animals were examined for changes that could be related to hyperoxia. Glutathione reductase activity of erythrocytes was reduced 5 to 29% by hyperoxia, whereas that of the plasma was not significantly altered. Significant changes in red and white cell counts, including differential leukocyte count, could not be detected. Electrophoretic analysis of the proteins and esterases derived from plasma and membranes and cytoplasmic fractions of erythrocytes did not reveal changes attributable to hyperoxia.

Animals↗
PubMed1999

Identification of S-(n-butylcarbamoyl)glutathione, a reactive carbamoylating metabolite of tolbutamide in the rat, and evaluation of its inhibitory effects on glutathione reductase in vitro.

Tolbutamide (TOLB), a widely used hypoglycemic agent in the therapy of non-insulin-dependent diabetes mellitus, has been reported to be teratogenic and/or embryotoxic in several animal species and humans. It has been proposed that the teratogenic effects of TOLB are linked to drug-mediated depletion of glutathione (GSH) through inhibition of the enzyme glutathione reductase (GR), although the mechanism by which this inhibition occurs remains unknown. In the study presented here, rats were injected with TOLB (200 mg/kg ip), and bile was collected for analysis by liquid chromatography/tandem mass spectrometry (LC/MS/MS). This led to the identification of S-(n-butylcarbamoyl)glutathione (SBuG), a reactive GSH conjugate derived from n-butyl isocyanate, as a minor metabolite of TOLB in bile. Upon incubation of SBuG (0.25-1.0 mM) with GR from either yeast or bovine intestinal mucosa in the presence of NADPH (0.20 mM), enzyme activity was lost in a time- and concentration-dependent manner. No inhibition was observed when NADPH was omitted from incubations, or when the natural substrate for the enzyme, glutathione disulfide (GSSG, 0.05 mM), was added. TOLB itself did not inhibit GR over the concentration range of 0.8-2.0 mM. It is concluded that metabolic activation of TOLB in vivo leads to the generation of reactive intermediates (n-butyl isocyanate and SBuG) which carbamoylate and thereby inhibit GR. At critical periods of organogenesis, the resulting perturbation of GSH homeostasis in exposed tissues may play a key role in the teratogenic and/or embryotoxic effects of TOLB.

Animals↗
PubMedDate not supplied

Postsynthetic changes of glutathione peroxidase (EC 1.11.1.9) and glutathione reductase (EC 1.6.4.2) in the ageing bovine lens.

Postsynthetic changes in the enzyme and structural proteins play an important role in the mechanisms of ageing of the lens, when development of protein aggregates and -S-S- linking occurs. Protection of the free -SH groups through the glutathione peroxidase and glutathione reductase system is a prerequisite to avoid these phenomena. Investigations on these two enzymes in young and old bovine lens tissues showed that they are themselves subjected to age-dependent modifications. With increasing age, the specific activity decreases while a simultaneous increase in heat lability occurs. This means that in the course of postsynthetic processes the stability of the conformation decreases and that finally the catalytic properties are lost.

Aging↗
PubMed2004

Glutathione reductase is expressed at high levels in pancreatic islet cells.

Reactive oxygen species are, at least partly, involved in the diabetogenic agent-induced dysfunction of pancreatic beta-cells because the expression of antioxidative and redox proteins is low. We examined the levels of antioxidant/redox proteins, peroxiredoxins-1, -4, and -6 and glutathione reductase (GR), by immunohistochemistry and found that the expression of GR was very high in pancreatic islet cells compared to exocrine cells. When diabetes was induced by an intravenous injection of streptozotocin, the pre-administration of 1,3-bis[2-chloroethyl]-1-nitrosourea, an irreversible inhibitor of GR, made islet cells more vulnerable to streptozotocin. These data point to a pivotal role of the glutathione redox system in pancreatic islet cells against diabetogenic stress.

Animals↗
PubMed1982

Chromosome localization of the genes for isocitrate dehydrogenase-1, isocitrate dehydrogenase-2, glutathione reductase, and phosphoglycerate kinase-1 in the American mink (Mustela vison).

Twenty-eight hybrid clones with different mink chromosomes were derived from the fusion of Chinese hamster and American mink (mustela vison) cells. This set of clones made it possible to assign the mink genes for isocitrate dehydrogenase-1 (soluble) to chromosome 4, for isocitrate dehydrogenase-2 (mitochrondrial) to chromosome 10, for glutathione reductase to chromosome 6, and for phosphoglycerate kinase-1 to the X chromosome.

Animals↗
PubMed2004

The glutathione reductase inhibitor carmustine induces an influx of Ca2+ in PC12 cells.

We studied the effects of carmustine (1,3-bis(2-chloroethyl)-1-nitrosourea) on the intracellular Ca(2+) concentration ([Ca(2+)](i)) in PC12 cells using fura-2 fluorescence imaging. Carmustine (100 microM) caused a delayed increase in [Ca(2+)](i) that developed within approximately 3 h. This effect was enhanced in cells that were pretreated with an inhibitor of glutathione (GSH) synthesis, buthionine sulfoximine (BSO, 200 microM, 24 h), and was suppressed in cells that were treated with an antioxidant deferoxamine (50 microM). The carmustine-induced increase in [Ca(2+)](i) was absolutely dependent on the presence of extracellular Ca(2+) and could be inhibited by dihydropyridine blockers of L-type voltage-gated Ca(2+) channels (nimodipine or nitrendipine, 10 microM). The increase in [Ca(2+)](i) was also suppressed in Cl(-)-free solution and in the presence of the Cl(-) channel blockers, indanyloxyacetic acid 94 (IAA-94, 100 microM) and 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB, 100 microM). The inhibition was complete when the blockers were applied simultaneously with carmustine and was partial when the blockers were applied after the initial increase in [Ca(2+)](i). We conclude that carmustine induces an influx of extracellular Ca(2+) through L-type Ca(2+) channels and that this effect is mediated by oxidative stress that results from the depletion of GSH following the inhibition by carmustine of glutathione reductase.

Animals↗
PubMed1985

Glutathione reductase of calf trabecular meshwork.

Hydrogen peroxide has been found in both calf and human aqueous humor at a level of 25 microM. It is likely, therefore, that trabecular meshwork possesses mechanisms for detoxifying H2O2, both to protect itself and other more distal structures of the outflow pathway from oxidative damage. We have recently demonstrated an active glutathione peroxidase in calf trabecular meshwork. In this study, we have characterized the complementary enzyme, glutathione reductase. The activity was present at a level of 0.120 units/min/g wet of tissue (0.005 units/min/mg soluble protein). The enzyme quickly lost activity in crude extracts but could be stabilized by heating at 60 degrees C for 30 min. Denatured protein was removed by centrifuging at 43,000 X g. Heating at 80 degrees C for 10 min destroyed all enzyme activity. Addition of 1 mM GSSG protected the enzyme completely from heat denaturation; NADP+ and GSH offered some protection but NADPH provided none. The supernatant from the 60 degrees C heat treatment was further purified by affinity chromatography on 2',5'-ADP-agarose. Overall purification was 200-fold with a yield of 80%. The pH optimum of the purified enzyme was 7.0. The KmS for NADPH and GSSG were 19 microM and 78 microM, respectively. The heat inactivation properties of the purified enzyme were identical to those in the crude extract. An enzyme activity stain on disc gel electrophoresis showed that the enzyme exists in only one form.

Animals↗
PubMed1983

Activity changes of glyoxalases I-II and glutathione reductase in regenerating rat liver.

In regenerating rat liver Glyoxalase I activity shows a significant increase 24-48 hrs after partial hepatectomy. Glyoxalase II activity is significantly increased at 16, 48, and 72 hrs, and shows a transient decrease at 24 hrs after surgery. It is likely that the observed changes in Glyoxalases I and II activities during hepatic regeneration are correlated with the different roles of these enzymes. Glutathione reductase activity, significantly reduced within 8-72 hrs after surgery, does not show any correlation with Glyoxalases. These studied enzyme activities do not display significant changes in the sham-operated animals.

Animals↗
PubMed1998

Low activity of superoxide dismutase and high activity of glutathione reductase in erythrocytes from centenarians.

OBJECTIVE: to compare the activities of antioxidative enzymes in erythrocytes between centenarians and a younger group of elderly subjects. DESIGN: cross-sectional study. SETTING: county of Funen, Denmark. SUBJECTS: 41 centenarians aged between 100 and 105 years and 52 community control subjects aged between 60 and 79 years. MEASUREMENTS: enzyme activities of superoxide dismutase (CuZn-SOD), glutathione peroxidase, catalase and glutathione reductase (GR) in erythrocytes. Functional capacity among the centenarians was evaluated by Katz' index of activities of daily living, the Physical Performance Test and Mini-Mental State Examination. RESULTS: the mean CuZn-SOD activity was significantly lower and the mean GR activity was significantly higher in centenarians than in the group of elderly people. The centenarians with the lowest cognitive and physical functional capacity and who did not survive at least 1 year after blood sampling tended to have the lowest CuZn-SOD activities. The range of GR activity was shifted toward higher values in the centenarian group than in the younger group and those centenarians having the best functional capacity tended to have the highest GR activity. CONCLUSIONS: CuZn-SOD activity is decreased in centenarians, probably because of reduced demand for the enzyme at lower metabolic rate and oxygen consumption. Subjects with high GR activity occur more frequently among centenarians than expected, possibly due to their better survival. The role of GR in disease prevention and as a predictor for longevity deserves to be further explored.

Activities of Daily Living↗
PubMed1995

Deficiency of two red-cell flavin enzymes in a population in Sardinia: was glutathione reductase deficiency specifically selected for by malaria?

In two areas in Italy where malaria was endemic--in the Po delta and Maremma on the west coast--we have found a high prevalence of an inherited flavin-deficient red cell in the normal population, suggesting selection by malaria. This study in Sardinia enabled a direct comparison of red-cell activities of FAD-dependent glutathione reductase (EGR) and FMN-dependent pyridoxine phosphate (PNP) oxidase in an ethnically homogeneous population, between two coastal villages where malaria was endemic from 300 B.C. and two mountain villages with no history of malaria. Both enzyme activities were significantly lower on the coast, and it did not seem that this could be explained by possible small differences in dietary riboflavin. As was thought to be the case in Ferrara and Grosseto, it is probable that a genetically controlled flavin-deficient red cell was selected for by malaria. Low EGR apoenzyme activity was more common on the coast, usually explaining the accompanying low basic EGR activity, and may also have been selected for by malaria. This adds to evidence from others that the mechanism of defence of a flavin-deficient red cell against malaria may be through EGR deficiency. It could also play a part in the protection given by heterozygous beta-thalassemia. The multifactorial protection of the population against malaria is discussed.

Adolescent↗