Total GSH-Px Activity Research Articles

Selenium supplementation during invitro maturation enhances meiosis and developmental capacity of yak oocytes.

The objectives of the present study were to investigate the effects of selenium (Se) supplementation during invitro maturation (IVM) on the developmental capacity of yak (Bos grunniens) oocytes. Nuclear maturation, DNA integrity, glutathione peroxidase (GSH-Px) activity, subsequent embryonic development, and gene expression after invitro fertilization (IVF) were evaluated. The Se concentrations in yak plasma and follicular fluid were 0.142 and 0.069μg/mL, respectively. The DNA damage in cumulus cells decreased significantly with 2 and 4μg/mL supplementation of sodium selenite to IVM medium (P<0.05). Total GSH-Px activity in oocytes increased in all Se supplementation groups, and the 2 and 4μg/mL groups were significantly higher than the control group (0μg/mL). However, the cleavage rate was not significantly different after Se supplementation (P>0.05). The IVF blastocyst formation rates of 0, 1 and 4μg/mL sodium selenite groups were 47.7%, 51.2% and 58.9%, respectively. The 2μg/mL sodium selenite group had the highest blastocyst formation rate (60.5%). Gene expression analysis revealed that the quantity of transcripts associated with selenoprotein and protein synthesis were high in the 2 and 4μg/mL groups. In conclusion, both GSH-Px activity of oocytes and DNA integrity of cumulus cells significantly increased with supplemental Se during oocyte IVM. Considering that embryonic development is responsive to Se supplementation, we inferred that appropriate Se concentrations during IVM were beneficial for yak oocyte maturation and subsequent development.

Glutathione dependent enzyme activities in the foot of three freshwater mussel species in the Sava river, Serbia

We investigated activities of glutathione peroxidase (GSH-Px), glutathione reductase (GR), and the phase II biotransformation enzyme glutathione-S-transferase (GST) in the foot of three freshwater mussel species: Unio pictorum (Up), Unio tumidus (Ut), and Sinanodonta woodiana (Sw) from the Sava River. Specific and total GSH-Px activity was lower in Sw than in Up and Ut. Total GR activity was higher in Up than in Sw. Specific GST activity was higher in Up than in Ut. Total GST activity was higher in Up than in Ut and Sw. Electrophoretic analysis of proteins shows species specifities between the investigated mussel species. Our study represents the first comprehensive report of the investigated glutathione-dependent enzyme activities in the foot of three freshwater mussel species from the Sava River, Serbia. .

Effects of chronic dietary cadmium on hepatic glutathione levels and glutathione peroxidase activity in starlings (Sturnus vulgaris).

The effects of chronic exposure to dietary cadmium on the levels of hepatic glutathione (GSH) and on the activity of the glutathione peroxidase enzymes (GSH-Px) were studied for the first time in starlings (Sturnus vulgaris). Thirty-three individuals (17 females and 16 males) were divided into three groups: One represented the untreated control and two were respectively fed with diets containing 10 and 50 ppm cadmium chloride (CdCl(2)). The total duration of treatment was 22 weeks. The three groups respectively accumulated mean hepatic Cd residues of 2.29, 75.71, and 208.49 ppm. Hepatic GSH increased in the treated groups respectively 24% and 52% in comparison to controls. Total GSH-Px activity in the liver was inhibited in the group fed with 50 ppm, due to inhibition of the selenium-dependent fraction of the enzyme, while the selenium-independent fraction did not change significantly. During the treatment, after 14 weeks of exposure to cadmium, the 50 ppm-treated group showed a 47% decrease of the activity of the selenium-dependent GSH-Px and a 50% increase of the somatic liver index in comparison with controls.

Effects of mild chronic heat exposure on the concentrations of thiobarbituric acid reactive substances, glutathione, and selenium, and glutathione peroxidase activity in the mouse liver.

To determine whether mild and chronic heat stress leads to oxidative stress and to differentiate such effects of different exposure periods, we kept male ICR-mice at an ambient temperature of either 35 degrees C or 25 degrees C for 6 hours, 3 days, or 7 days and measured the concentrations of thiobarbituric acid reactive substances (TBARS), glutathione (GSH), selenium (Se), and glutathione peroxidase (GSH-Px) activities in the liver. Since the food consumption of the heat-exposed group was only half that of the control, we prepared pair-fed groups, which were kept at 25 degrees C and whose food consumption were limited to those of the heat-exposed group for the 3-day and the 7-day exposure. TBARS concentrations of the liver was significantly higher in the heat group than the control after the 3-day exposure, while there was no significant difference among the groups after the 7-day exposure. There was no significant difference in GSH concentrations between the heat-exposed group and the control after the 7-day exposure, when the GSH concentration of the pair-fed group was significantly lower than that of the control. Hepatic cytosolic Se GSH-Px activity in the heat group was significantly less than that in the control group after the 6-hour exposure and it tended to be lower in the heat group than that of the control group after the 7-day exposure, while there was no difference in the total GSH-Px activity among the three groups. Our results showed that mild and chronic heat exposure may cause oxidative damage to organisms and that GSH-related anti-oxidative systems would play an important role to defensive reaction.

Antioxidant and detoxifying fish enzymes as biomarkers of river pollution

The activity of several antioxidant and detoxifying enzymes, superoxide dismutase SOD, GSH peroxidase GSHPx, GSSG reductase GSR and GSH S transferase GST, the contents of thiobarbituric acid reactive substances TBARS, and the SOD and GST isoenzyme patterns were studied in the livers of chubs Leuciscus cephalus from reference river areas and polluted urban sites. Livers of polluted fish contained higher concentrations of transition metals, especially copper and iron. Total GSHPx activity was 1.8 fold higher in the polluted fish than in reference animals, while the SOD and GSR activities and the TBARS content were not significantly changed. Three new SOD isoforms pI 4.45, 5.1, 5.2 and a higher intensity of the band pI 4.2 were observed after isoelectrofocusing of polluted fish extracts. Total GST activity was higher in fish from polluted areas. The GST isoenzyme pattern was studied using subunit specific substrates DCNB, EPNP, EA, NPB, NBC and by Western blot using antibodies specific to rat GST subunits 1, 8 Alpha class, 3 Mu class and 7 Pi class. Reference and polluted fish lacked cross reactivity towards Alpha class GSTs. Reference fish displayed weaker cross reactivity towards CST 7 and 2.3 fold lower activity with EA, while higher cross reaction with GST 3 was observed in polluted fish.

Changes in pancreatic glutathione peroxidase and superoxide dismutase activities in the prediabetic diabetes-prone BB rat.

Pancreatic superoxide dismutase (SOD) and glutathione peroxidase (GSHPx) activities were measured during the development of diabetes in diabetes-prone BB rats (BBdp) prior to insulin dependence. The pancreata from seven to eight BBdp rats of each sex were examined at ages 5, 7, 10, and 18 weeks and compared with age-matched control BB rats (BBc). At Week 18, BBdp rats had moderate to high insulitis but normal levels of blood glucose and insulin. Pancreatic CuZnSOD activity in BBdp rats was two times higher than the activity seen in BBc rats at age 5-10 weeks but then declined to the same level as seen in BBc rats at 18 weeks of age. MnSOD activity increased over time in the BBdp rats but remained very low in BBc rats. These changes in CuZnSOD and MnSOD activity resulted in BBdp rats having twice the pancreatic total SOD activity compared with BBc rats (P < 0.0001). Total GSHPx activity was significantly reduced in the pancreata from both male and female BBdp rats compared with their respective controls (P < 0.01 and P < 0.0001, respectively). The lower total GSHPx activity was due to reduced selenium-dependent GSHPx (SeGSHPx) activity. Erythrocyte and plasma activity of these enzymes was not different between rats with or without insulitis, indicating that differences in enzyme activities were confined to the pancreas. Thus, changes in pancreatic antioxidant enzyme activities occur prior to the development of diabetes symptoms in BBdp rats and may be related to the destruction of the pancreatic B cells and ultimate development of diabetes.

Dietary Se and tumor glutathione peroxidase and superoxide dismutase activities

The purpose of this study was to examine tumor activity of the radical scavenging enzymes selenium dependent glutathione peroxidase (SeGSHPx), cupro,zinc-superoxide dismutase (CuZnSOD), and manganese dependent SOD (MnSOD) from rats fed varying amounts of selenium and to compare the effects due to diet with those due to the development of the tumor. Enzyme activities were measured in mammary tumors from DMBA-treated rats fed 0.035, 0.1, 1.0, and 2.0 mg Se/kg diet for 25 weeks ( n = 58,33,24, and 14 tumors from 8, 8, 7, and 8 tumor-bearing rats, respectively). Increasing dietary Se had no effect on tumor SeGSHPx, non-SeGSHPx, and MnSOD activities. In contrast, tumor CuZnSOD and total SOD activities decreased with increasing dietary Se. Tumor size had a significant effect on MnSOD, SeGSHPx, non-SeGSHPx, and total GSHPx activities with increasing activity observed with increasing tumor weight. Malignant tumors were unique in two ways with respect to the activity of antioxidative protective enzymes. Tumor SeGSHPx activity was unresponsive to dietary Se while CuZnSOD and total SOD activities were significantly reduced with increasing dietary Se compared to erythrocytes, liver, and spleen from the same animals. Thus, the overall effect of high dietary Se was to decrease the ratio of total SOD to total GSHPx activity ( P < 0.003). Tumor size had no effect on the ratio. This ratio of total SOD/GSHPx activity was several-fold higher in tumors than in other tissues from the same animals.

Role of Selenium‐Dependent Glutathione Peroxidase in Protecting against t‐Butyl Hydroperoxide‐Induced Damage in Hepatocytes

The role of the selenoenzyme glutathione peroxidase (Se-GSHPx) in protecting against oxidative injury was studied in hepatocytes isolated from rats fed either a low-selenium (Se-) or a selenium-adequate (Se+, control) diet. In rats fed Se- diet for eight weeks the selenium content of plasma and liver was lowered to 15 and 8%, respectively. No Se-GSHPx and only 5% of total GSHPx activity was detected in Se- hepatocytes. However, the Se- hepatocytes were as resistant as the Se+ cells to oxidative injury by 0.8 mM tert-butyl hydroperoxide (t-BuOOH), or 0.2 mM t-BuOOH plus 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), an inhibitor of oxidized glutathione (GSSG) reductase. Only at 1.5 mM t-BuOOH or at 0.5 mM t-BuOOH with BCNU were cell damage and lipid peroxidation more evident in Se- cells. At all t-BuOOH concentrations used the depletion of cellular glutathione (GSH) was similar in magnitude in Se- and Se+ cells, but Se+ cells released more glutathione (mainly GSSG), obviously due to their higher Se-GSHPx activity. These results suggest that hepatocytes devoid of Se-GSHPx activity maintain a high capacity to resist peroxidative attack, either via residual (non-Se)GSHPx activity or other compensatory GSH-associated detoxication mechanisms.

Seasonal changes in total and selenium-dependent glutathione peroxidase activity in bovine semen in relation to lipid peroxide

There were significant seasonal changes in total and selenium-dependent glutathione peroxidase activity and level of lipid peroxide in bull whole semen. Increased selenium-dependent GSH-Px in autumn and total GSH-Px activity in winter may decrease the rate of lipid peroxidation in bovine semen.

Non-selenium-dependent glutathione peroxidase activity in rat lung: Association with lung glutathione S-transferase activity and the effects of hyperoxia

To determine if non-selenium-dependent glutathione peroxidase (Non-Se GSH-Px) activity is present in rat lung, we fractionated rat lung soluble fractions from rats fed a selenium-deficient or control diet and measured glutathione peroxidase activity with both cumene hydroperoxide and hydrogen peroxide as substrates. We also measured glutathione S-transferase (GSH S-transferase) activity in the fractions with 1-chloro-2,4-dinitrobenzene as substrate. Non-Se GSH-Px activity was present (about 34% of total GSH-Px activity), and the peak present in the gel filtration chromatogram coeluted with the GSH S-transferase peak. We then measured GSH S-transferase activity in lung-soluble fractions from rats exposed to room air or 85% O 2 for 5 days. Lung GSH S-transferase activity was increased in the oxygen-exposed animals when compared to the air-exposed controls. The increase in GSH S-transferase activity could represent the induction of lung non-Se GSH-Px activity.

Influence of Dietary Peroxides, Selenium and Vitamin E on Glutathione Peroxidase of the Gastrointestinal Tract

The influence of dietary peroxides, vitamin E and selenium on glutathione peroxidase (GSH-Px) activity in the gastrointestinal tract of the rat was investigated. Feeding 7% oxidized stripped corn oid (peroxide value 1,000) in a diet adequate in selenium and vitamin E increased the specific activity of GSH-Px in the stomach mucosa. Feeding oxidized oil produced an increase in the wet weight of the intestinal mucosa which was associated with a decrease in the specific activity of the enzyme. Total GSH-Px activity in the intestinal mucosa was unchanged or moderately increased. These changes were unaffected by the presence of vitamin E in the diet. Dietary peroxides had no effect on GSH-Px activity in the plasma or in the perirenal and paraepididymal adipose tissues. Subacute vitamin E deficiency had no consistent effect on the activity of the enzyme in several tissues examined. In rats fed a Se deficient diet glutathione peroxidase activity decreased markedly in most tissues but only slightly in the intestinal mucosa. The moderate decrease in the intestine may be explained by the accessibility of residual dietary Se to the mucosal cells. The role of Se in the detoxification of peroxides in foods and the response of gastrointestinal GSH-Px to dietary peroxides are discussed.