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PubMed2005

Influence of melatonin on cell proliferation, antioxidative enzyme activities and lipid peroxidation in 3T3-L1 preadipocytes--an in vitro study.

Melatonin, acting via MT1, MT2 and MT3 membrane receptors, influences central and peripheral regulatory mechanisms of energy homeostasis in mammals. In peripheral tissues, it evokes the pro-proliferative effect in a number of normal cells. Moreover, this hormone inhibits lipolysis in subcutaneous adipocytes in vitro and reduces free oxygen metabolites-induced damage acting directly, as a free radical scavenger, and indirectly, by stimulation of antioxidative enzyme activities. The aim of the study was to examine the effects of melatonin on cell proliferation, antioxidative enzyme activities and malondialdehyde (MDA) concentration in 3T3-L1 preadipocyte cell culture. We found that melatonin (10(-3) and 10(-6) M/L) stimulated cell proliferation in dose- and time-depending manner, and this effect was inhibited by a relatively selective MT2 receptor antagonist - luzindole (10(-4) M/L). Melatonin, increased activities of manganese containing and copper-zinc containing superoxide dismutase (MnSOD and Cu/ZnSOD) isoenzymes, catalase, glutathione reductase and glutathione peroxidase after 24 h of incubation. In contrast, after 48 h of incubation, activities of all studied enzymes were lower than in the control group. There were no changes in MDA concentrations after 24 h of incubation, whereas, in melatonin-treated media, after 48 h of the experiment, MDA level was significantly decreased. Our results demonstrate that melatonin, acting via MT2 receptors, stimulates proliferation of 3T3-L1 preadipocytes and this action could be due to the enhancement in antioxidative enzyme activities and attenuation of lipid peroxidation by this indole.

3T3-L1 Cells↗

PubMed1991

[Status of the processes of free-radical oxidation and the antioxidation system in patients with a severe course of hepatitis B].

Sixty patients with severe forms of acute viral hepatitis B (AVHB) without symptoms of acute hepatic encephalopathy (AHE) and 20 AVHB patients with such symptoms were examined for red blood cell and serum levels of dienic conjugates (DC), malonic dialdehyde (MDA), reduced glutathione (RG), activity of superoxydismutase (SOD), catalase, glutathione peroxidase-1 (GP1), glutathione peroxidase-2 (GP2), glutathione reductase (GR), glutathione transferase (GT). Elevated MDA and DC concentrations were found in grave AVHB, in coma and precoma DC reduced. MDA levels in precoma fell, in coma rose. The activity of SOD, GP1, GP2, GR and RG concentration were low, especially in AHE symptoms. GT and catalase activity proved high in severe AVHB with a trend to lowering in precoma and coma.

Antioxidants↗

PubMed1990

Role of glutathione in the regulation of anterior chamber hydrogen peroxide.

Catalase inhibition leads to an increase in the t 1/2 for hydrogen peroxide loss from the anterior chamber and increased tissue damage. BCNU (1,3-bis-(2-chloroethyl)-l-nitrosourea) and BSO (buthionine sulfoxamine) were used to suppress glutathione reductase and glutathione synthesis, respectively. Intravitreal BSO (1 to 4 mg) reduced total glutathione levels of iris by 80%, and aqueous glutathione levels by 70%. BSO caused the t 1/2 for hydrogen peroxide disappearance from the anterior chamber to increase after 10 microliters of 10 mM peroxide was injected intracamerally but not after 25 or 50 mM peroxide injections. Catalase inhibition, however, had more influence at 50 mM than with 10 or 25 mM injections. The glutathione redox system is operative at low aqueous hydrogen peroxide concentrations and catalase is of greater importance at higher peroxide concentrations.

Amitrole↗

PubMed1987

[The function of enzymes for the antioxidative protection of the bone marrow cells in rats during irradiation, bone fracture and combined radiation injury].

The activity of superoxide dismutase, glutathione peroxidase, glutathione reductase and glutathione: dehydroascorbate oxidoreductase is lower in the bone marrow than in the liver. The changes in the cellular antioxidative enzymatic system during leg bones fracture and X-ray irradiation are more pronounced in the rat bone marrow, as compared to the liver. The data obtained are in keeping with selective bone-marrow radiosensitivity and with the effect of exogenous superoxide dismutase and glutathione as radioprotectors.

Acute Disease↗

PubMedDate not supplied

[Effect of vitamin E from by-products of cotton oil processing on the glutathione peroxidase system in rats].

The activities of glucose-6-phosphate dehydrogenase, glutathione reductase and glutathione peroxidase from liver, skeletal muscles and erythrocytes of rats fed a vitamin E-deficient, or supplemented, diet were studied. Vitamin E was added in the diet either as a pure pharmacy form of alpha-tocopherol or as a tocopherol mixture derived from oil wastes. The deficiency of vitamin E caused an increase in the activity of the above mentioned enzymes. Both alpha-tocopherol and the tocopherol mixture were found to influence the glutathione peroxidase system. The dose-dependent response of the glutathione peroxidase system was revealed. Possible mechanisms of the changes in the antioxidizing enzymes induced by vitamin E are discussed.

Animals↗

PubMed1979

Differential sensitivity of tumor cells to externally generated hydrogen peroxide. Role of glutathione and related enzymes.

(1) Oxygen uptake and lactate production of different strains of ascites tumor cells were assayed after exposure to an extracellular photochemical system known to produce reactive oxygen derivatives. The various cells tested showed differential sensitivity to the treatment, ranging from nearly full inactivation of Ehrlich cells to nearly full resistance of Yoshida cells. (2) Glucose plus succinate added after the treatment reestablished basal oxygen uptake capacity suggesting that the cell membrane was the primary site of damage. This was confirmed by dye-permeabilization and protein leakage in sensitive cells. (3) H2O2 was shown to be the only relevant oxygen derivative in the production of cell damage: catalase was the only externally added agent that protected sensitive cells, and H2O2 (congruent to 10(-3) M) had the same effects as the photochemical treatment. (4) While the absence of catalase is a feature common to all tumors tested, sensitivity to H2O2 appears to be related to cellular levels of glutathione peroxidase and of its subsidiary enzymes glucose-6-phosphate dehydrogenase, glutathione reductase and glutathione synthetase.

Animals↗

PubMed1995

Biochemical changes in heat stressed promastigotes of Leishmania donovani.

On exposing promastigotes of L. donovani (Dd-8) to 34 degrees C for 30 hr, the flagella were shed, and size was decreased with 10% viability loss. The in vitro and in vivo infectivity of two forms was more or less similar. The 45Ca2+ uptake by the transformed cells was increased as compared to normal cells. Activity of 5'-nucleotidase was increased while activity of Mg(2+)-ATPase remained same. Parasite antioxidant enzymes were also significantly altered by heat shock. There was significant increase in superoxide dismutase, glutathione reductase and glutathione peroxidase. It was accompanied by decrease in ratio of reduced glutathione to oxidized glutathione.

Animals↗

PubMed1994

Erythrocyte antioxidant enzyme activity in CMF treated breast cancer patients.

Most of breast cancer patients are treated with CMF, which is a combination of three anticancer agents, cyclophosphamide, methotrexate and 5-fluorouracil. Metabolites of CMF induce lipid peroxidation by inactivating the antioxidant enzymes, thereby rendering the system inefficient in management of the free radical attack. Acrolein and phosphoramide mustard are the metabolites of cyclophosphamide which are among the causative agents which reduce the activity of superoxide dismultase, catalase, glutathione peroxidase, glutathione reductase, glutathione-S-transferase and glucose-6-phosphate dehydrogenase in erythrocytes of CMF treated breast cancer patients.

Antineoplastic Combined Chemotherapy Protocols↗

PubMedDate not supplied

[Effect of the drug stibyl on the enzymatic activity of the antioxidant defense system in chickens].

We have investigated the change of peroxidase, catalase, glutathione reductase and glutathione peroxidase activity in the organs and tissues of chickens when introducing the products of albumens interaction with carbohydrates into the ration under the conditions of Maiyer's reaction (stibel preparation). It was found that the effect of stibel on the activity of antioxidant enzymes of chickens has age peculiarities. When introducing the addition to the chickens ration in the starting period (1-30 days) it causes the decrease of superoxide dismutase and catalase activity, and increase of peroxidase and glutathione peroxidase activity. In the finishing period (30-59 days) the drug stimulates the activity of superoxide dismutase and inhibits other enzymes of the chicken antioxidant system. The degree of expression of the mentioned effects depends on the organ specificity and on the nature of albumen and carbohydrate components of food addition and also on the ration saturation with metabolic energy and protein.

Animals↗

PubMedDate not supplied

[Tocopherol level and lipid peroxidation in Wistar rat tissues during adaptation to cold].

The content of lipid peroxidation (LPO) products and tocopherol was studied in the plasma, adrenals, brown fat, heart, thymus, liver tissue, microsomes and mitochondria of Wistar rats in various periods of cold acclimation (+4 degrees C during 2, 5, 24 hours and 5, 10, 15, and 49 days). Within the first 24 hours of cold exposure, there were periods of low levels of LPO products which, as their following elevation, did not coincide in time both for various tissues and for subcellular structures. The liver was used as an example to show that the activity of glutathione reductase and glutathione peroxidase enhanced. The rats' adaptation to moderately low temperatures occurred with the stabilized LPO processes and elevated body's tissue tocopherol levels: in the first hours of exposure by mobilizing its endogenous stores, on long-term exposure by enhancing its utilization from the diet.

Adaptation, Physiological↗

PubMed1996

Anti-oxidant enzymes, gamma-glutamyl transpeptidase and lipid peroxidation in kidney of rats exposed to cigarette smoke.

Glutathione reductase (GR), glutathione peroxidase (GSH Px) and catalase (Cat) were determined in the kidneys of rats exposed to cigarette smoke for 3 months. Activity of the brush-border enzyme gamma-glutamyl transpeptidase (GGT), glutathione (GSH) and lipid peroxide levels (LPX) were also estimated in both, kidney homogenates and urine. Activities of GR, Cat, GGT and the levels of GSH were decreased in the kidney. However, the activities of GSH Px and LPX levels were increased. Urinary excretion of GGT, GSH and LPX were also higher. Fall in the activity of GR and rise in the activity of GSH Px, may perturb the reduced glutathione/oxidised glutathione ratio, which in turn could lead to increased LPX seen in chronic cigarette smoke exposure.

Animals↗

PubMedDate not supplied

Elevation of mouse liver glutathione level by low-dose gamma-ray irradiation and its effect on CCl4-induced liver damage.

We examined the elevation of glutathione (GSH) levels in the liver of C57BL/6 female mice after low-dose r-ray irradiation and its inhibitory effect on CClI4-induced liver damage. The liver GSH level increased soon after irradiation with 50 cGy of gamma-rays, reached a maximum at around 12 post-treatment, and returned almost to the control level by 24 h. The activities of glutathione reductase, and glutathione peroxidase also showed the same pattern of change, while the activity of gamma-glutamylcysteine synthetase showed a gradual increase up to 24 h. The effect of pre-irradiation on CCl4-induced liver damage was also investigated. The activities of glutamic oxaloacetic transaminase and glutamic pyruvic transaminase in serum were markedly increased 12 h post-treatment with CCl4. Both increases were significantly suppressed by a single low-dose pre-irradiation. Malondialdehyde, a marker of lipidperoxidation, was also greatly elevated after CCl4 treatment, and its increase was suppressed by irradiation. These results suggest low-dose gamma-ray irradiation might be effective for the prevention of and/or therapy of various reactive oxygen species-related diseases including cancer.

Animals↗

PubMedDate not supplied

[Antioxidants of blood enzymes in kidney function disorders in man].

The activities of lipid peroxidation processes and enzymes of antioxidant system in the blood of patient with renal failure have been studied. The results demonstrated stimulation of lipid peroxidation processes in blood serum, cellular membranes of erythrocytes and in urine. The study of the antioxidant system discovered the inhibition of various enzymes: superoxide dismutase and peroxidase, inhibiting production of active oxygen forms; transferring and ceruloplasmin as regulators of Fe2+/Fe3+ ratio, glutathione reductase and glutathione peroxidase influencing the ratio of oxidated and reduced glutathione forms and the level of SH-groups. So, determination of lipid peroxidation processes and antioxidant enzymes in blood is the sensitive inform test in diagnostics of chronic renal failure.

Antioxidants↗

PubMed1998

Biochemical characterization of in vivo alkylating agent resistance of a murine EMT-6 mammary carcinoma. Implication for systemic involvement in the resistance phenotype.

While cancer drug resistance has been extensively studied in cell culture, little is known about more clinically relevant in vivo resistance. The in vivo resistance of a murine mammary carcinoma EMT-6 to alkylating agents was demonstrated in the present study to be associated with multiple biochemical changes. These included an up to 1.5-fold increase in activity of phase II drug metabolizing enzymes (DMEs), such as glutathione (GSH), glutathione reductase (GR), glutathione S-transferase (GST), glutathione peroxidase (GPX) and aldehyde dehydrogenase (ALDH), and an up to 88% decrease of phase I DME activity [7-ethoxycumarin O-deethylase (ECOD), P450 reductase (PR)] in the resistant tumors compared with the parental tumor. Transplant of either parental or resistant tumors to mice was accompanied by a decrease of both phase I and phase II DME activity in the livers of female Balb/C mice compared with the non-tumor mice. Moreover, at the protein level, while cytochrome P450 (CYP) IIB1/2 in the liver of mouse bearing both the sensitive and the resistant tumor was significantly diminished compared to that in the liver of non-tumor control mouse in Western analysis, there was actually an increase of this protein in the liver of the host bearing either of the two resistant tumors compared to that of the sensitive tumor-bearing animal. Although this in vivo resistance phenotype is not expressed in cell culture, the profile of most of the enzyme changes in the resistant tumors remained similar in in vitro culture of the isolated tumor cells. Collectively, these results demonstrate that this in vivo alkylating agent resistance is associated with multiple changes of both phase I and phase II DMEs in the resistant tumors, and some of these, such as CYP IIB1/2 protein are further altered in the resistant tumor-bearing mouse liver, suggesting a potential role of systemic factors in this resistance phenotype.

7-Alkoxycoumarin O-Dealkylase↗

PubMed1985

1-Methyl-4-phenyl-pyridinium-induced inhibition of nicotinamide adenosine dinucleotide cytochrome c reductase.

The effect of 1-methyl-4-phenyl-pyridinium (MPP+), the main toxic metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a parkinsonism-causing neurotoxin, upon the activity of nicotinamide adenine dinucleotide (NADH) cytochrome c reductase (EC 1.6.99.3) and upon that of glutathione reductase (EC 1.6.4.2) was monitored spectrophotometrically. For the cytochrome c reductase, the increase in absorbance of reduced cytochrome c was measured at 550 nm; for evaluating glutathione reductase, the absorbance of nicotinamide adenine dinucleotide phosphate (NADPH) was followed at 340 nm. MPP+ but not MPTP reversibly inhibited NADH cytochrome c reductase, but not glutathione reductase. This may be a direct mechanism of cell toxicity by this neurotoxin.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

PubMed1987

Trypanothione reductase from Trypanosoma cruzi. Purification and characterization of the crystalline enzyme.

The structural differences between trypanothione reductase of Trypanosoma cruzi and human glutathione reductase, an enzyme of known three-dimensional structure, offer an opportunity for rational drug design against Chagas' disease. As a first step in the analysis of the parasite enzyme we report its purification and characterization. 2.2 mg trypanothione reductase was extracted from 33 g wet weight of cultured epimastigotes or from 4 g lyophilized cells. The flavoenzyme was purified 2400-fold to homogeneity in three steps with an overall yield of 45%. The enzyme is a dimer with a subunit Mr of 50,000. Using NADPH (Km = 5 microM) and trypanothione disulfide (Km = 45 microM) as substrates, a turnover number of 14,200 min-1 was estimated. Trypanothione reductase, the parasite enzyme, and glutathione reductase, the host enzyme, exhibit mutually exclusive specificities for their respective disulfide substrates. When screening cell cultures or column eluates for the presence of trypanothione reductase, a microassay based on Ellman's reagent as indicator was used. A mixture of regioisomeric glutathionylspermidine disulfides isolated from Escherichia coli served as substrate in this microassay. Experimentally, the catalytic cycle of the enzyme can be subdivided into the half-reactions Eox + NADPH + H+----EH2 + NADP+, and EH2 + trypanothione disulfide----Eox + dihydrotrypanothione. This is also true for the crystallized enzyme in the presence of 2 M (NH4)2SO4. The spectral properties of trypanothione reductase both in the oxidized form (Eox) and in the two-electron-reduced form (EH2) closely resemble those of human glutathione reductase. Both proteins contain a flavin and a redox-active disulfide at the catalytic site. After reduction of Eox to EH2, trypanothione reductase can be inactivated by specifically alkylating one of the nascent active-site thiols.

Animals↗

PubMedDate not supplied

[Photoperiodic changes of the glutathione system of the brain under acute hypoxia].

The effect of acute hypoxic hypobaric hypoxia on the content of reduced glutathione and the activity of glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase and glutathione S-transferase, as well as 5'-nucleotidase in homogenates of juvenile male rats under conditions of varying photoperiodic duration: natural conditions of illumination, continuous illumination and continuous darkness were studied. Photoperiodic changes were revealed in the glutathione system of the control animals: the activity of glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase reduces under constant light, while the activity of glutathione peroxidase and glutathione S-transferase increases under conditions of constant darkness. The greatest inhibitory effect on the state of the glutathione system is brought about by constant light in case of acute hypoxia: the content of reduced glutathione decreases along with a sharp drop of the activity of glutathione S-transferase and glucose-6-phosphate dehydrogenase, observed against the background of decreased glutathione reductase activity. Permanent dark conditions eliminate partially or completely the negative effect of acute hypoxia on the glutathione system of the brain. The obtained results are indicator of a possibility of protecting role of melatonin in case of acute hypoxia.

5'-Nucleotidase↗

PubMed1993

Effect of long-term exposure to cold on the antioxidant defense system in the rat.

Catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR), and glutathione-S-transferase (GST) activities as well as glutathione (GSH), ascorbic acid (AsA), and vitamin E concentrations were analyzed in the blood, liver, brain, interscapular brown adipose tissue (IBAT), and small intestine of rats exposed to low environmental temperature (4 degrees C; 35, 75, and 105 d of exposure) and in controls of the same age exposed to an environmental temperature of 22 +/- 2 degrees C. Prolonged cold exposure resulted in an increase in GSH-Px in IBAT and in small intestine after 35, 75, and 105 d of exposure. Catalase activity in cold-exposed animals was higher in IBAT after 75 and 105 d of cold exposure. Glutathione reductase activity was greater in brain after 35 d, in liver after 75 d, and in IBAT after 105 d of exposure to low temperatures as compared to the controls. In contrast, GST activity was lower in liver and IBAT after 35 and 75 d of cold exposure. AsA and GSH (determined only 105 d after cold exposure) were markedly higher in IBAT, whereas plasma GSH was lower and plasma AsA was higher in cold-exposed animals. The observed changes in analysed components of the antioxidant defense system under conditions of prolonged exposure to low temperature suggest that a reorganization the activity of this system at the molecular level occurred. Although other studies indicate that a 21-d cold exposure is sufficient for adaptation of thermogenesis, the present study shows that in general, longer periods are required for the registration of the changes in the antioxidant defense system.

Adipose Tissue, Brown↗