Serum selenium concentration and glutathione peroxidase activity and selenium content in testes of Polish Konik horses from selenium- -deficient area in North-Western Poland

The aim of this study was to determine serum selenium concentrations in Polish Konik horses residing in the Odra Delta Nature Park (Poland) and to evaluate the activity of glutathione peroxidase and Se content in testes of this horse breed. In over 95% of cases, serum Se concentration was below the optimal range, and none of the horses examined was deficient in this trace element. The lack of Se deficiency in the animals examined suggests however, that the Polish Konik horses have a natural ability to the optimal use of nutrients available in their life area. Testicular content of Se and GSHPx activity in the colts was higher than those found in stallions, and a positive relationship between these antioxidants was demonstrated. The differences in Se contents and GSHPx activities in testes between colts and stallions suggest that selenoenzymes play important roles during the puberty of male horses.

Effect of diets with different inclusion levels of distillers dried grain with solubles combined with lysine and methionine supplementation on the lipid peroxidation and glutathione status of chickens

To study the possible effects of different inclusion levels of distillers dried grain with solubles (DDGS) on the lipid peroxidation and glutathione redox status of chickens, 200 three-week-old Ross 308 cockerels were assigned to four treatment groups of 50 birds each. The groups were fed a control and three experimental, isocaloric and isonitrogenous grower diets containing 15, 20 and 25% DDGS, respectively, combined with lysine (Lys) and methionine (Met) supplementation until 6 weeks of age. It was found that DDGS inclusion increased the ether extract content of the diets which resulted in higher reduced glutathione (GSH) content and elevated glutathione peroxidase activity (GSHPx) in the liver. However, DDGS addition with Lys and Met supplementation did not influence the malondialdehyde content of the blood and the liver. The oleic acid proportion of the diet showed a close positive correlation with GSH content of the liver. A smaller ratio of methionine and cysteine in the diet with DDGS resulted in significantly higher liver GSH content. GSHPx activity increased parallel with the elevated GSH content of the liver homogenate, suggesting that the enzyme is activated by the actual supply of its co-substrate. In conclusion, the results show that DDGS, even at a high inclusion level combined with Lys and Met supplementation, has no initiative effect on lipid peroxidation in the blood and liver of broiler chickens.

Selenium Status in Heifers, Late Pregnancy Cows and Their Calves in the Šumava Region, Czech Republic

The objective of this study was to ascertain selenium status in beef cattle in different stages of production in the Šumava region. In the region, blood collections and analyses for selected metabolic variables were performed in 54 animals in different production stages (18 heifers, 18 cows in late pregnancy and 18 calves aged 3 weeks on the average). Three herds were studied. The selenium status was determined both directly by measuring serum selenium (Se) contents and indirectly by measuring glutathione peroxidase (GSH-Px) activity in whole blood. The mean serum selenium concentration in all the animals under study (n = 54) was 30.6 μg/l +/- 2.91, and mean GSH-Px activity was 167.01 μkat/l +/- 92.39. In heifers, mean serum selenium concentration was 34.81 μg/l +/- 13.84; mean GSHPx activity was 186.96 μkat/l +/- 112.15. In late pregnancy cows, mean serum selenium concentration was 26.58 μg/l +/- 8.01, mean GSH-Px activity was 94.55 +/- 35.72 μkat/l. In calves, mean serum selenium concentration and GSH-Px activity were 30.41 μg/l +/- 12 and 219.54 μkat/l +/- 64.41, respectively. There was a statistically significant difference between the heifers and late pregnancy cows in both variables under study. However, between the late pregnancy cows and the calves, only the difference in GSH-Px activity was significant. The results indicate severe Se deficiency in the animals under study. It means apart from other things that mineral licks used did not provide enough minerals to meet the basic requirements of the animals.

Bioavailability of selenium from raw or cured selenomethionine-enriched fillets of Atlantic salmon (Salmo salar) assessed in selenium-deficient rats

The bioavailability of Se from raw and cured selenomethionine-enriched (Se-enriched) salmon fillets was assessed in Se-deficient male albino rats (Mol: Wist). A low-Se Torula yeast feed was supplemented with 0, 50, 100, 150 or 200 μg Se/kg as sodium selenite or as Se from raw or cured Se-enriched salmon. The diets were fed to weanling rats for 10 and 30 d. Bioavailability of Se was assessed by metabolic balance, Se accumulation in femur, muscle, liver and plasma, and induction of Se-dependent glutathione peroxidase (EC 1·11·1.9; GSHpx) in plasma as response parameters. Except for the metabolic balance results, the slope-ratio method was used when calculating Se bioavailability from raw or cured Se-enriched fish fillets (test food) relative to sodium selenite (standard). The data for fractional apparent absorption and fractional retention showed differences (P<0·05) among all three Se sources in the order raw salmon > cured salmon > selenite. At 10 d, Se from raw and cured Se-enriched fish fillets tended to be more bioavailable than selenite. This was supported by the observations for Se accumulation in femur and muscle and induction of GSHpx activity. At 30 d, all response parameters showed a higher bioavailability of Se from raw and cured Se-enriched fish fillets compared with selenite. Differences (P<0·05) in Se accumulation in muscle at 10 and 30 d, and differences (P<0·05) in fractional apparent absorption and fractional retention suggested that curing salmon altered the utilisation of Se. The experimental results showed that enrichment of fish fillets with selenomethionine yields fillets with high Se bioavailability.

Effects of methionine on endogenous antioxidants in the heart

The deficiency of methionine, an essential amino acid, is associated with cardiovascular lesions. Because different types of cardiac pathologies are caused by a decrease in antioxidants, we examined the effects of methionine on myocardial antioxidant enzymes in hemodynamically assessed rats that were treated with methionine (10 mg/ml) in drinking water for 12, 24, and 48 h. Glutathione peroxidase (GSHPx) activity was significantly increased to 150.5 ± 12.2 and 191.7 ± 13.7% of the control value at 12 and 24 h, respectively, followed by a decline to 120 ± 24.6% at 48 h. The mRNA levels of GSHPx at these time points were 151.2 ± 12.0, 218.7 ± 35.3, and 173.5 ± 25.2%, respectively. Superoxide dismutase (SOD) activity was 144.3 ± 3.7, 114.3 ± 10.1, and 143.1 ± 11.2% at 12, 24, and 48 h, respectively. Catalase (Cat) activity was 272.4 ± 5.4, 237.8 ± 16.6, and 224.1 ± 17.3% of the control value. The expression of Cat and SOD mRNA was unchanged at 12, 24, and 48 h. The lipid peroxidation was decreased by 24.4 ± 11.2, 54.9 ± 0.1, and 6.4 ± 2.1% at 12, 24, and 48 h, respectively. Methionine had no effect on the ventricular or aortic pressures, heart rate, and myocardial glutathione levels at any of the time points. The study shows that methionine has a significant effect on the myocardial antioxidant enzyme activities, and only changes in GSHPx enzyme activity correlated with the mRNA changes. These antioxidant changes may have a role in the beneficial effects of methionine in pathological rather than physiological conditions.

Inhibition of I kappa B-alpha phosphorylation and degradation and subsequent NF-kappa B activation by glutathione peroxidase overexpression.

We report here that both kappa B-dependent transactivation of a reporter gene and NF-kappa B activation in response to tumor necrosis factor (TNF alpha) or H2O2 treatments are deficient in human T47D cell transfectants that overexpress seleno-glutathione peroxidase (GSHPx). These cells feature low reactive oxygen species (ROS) levels and decreased intracellular ROS burst in response to TNF alpha treatment. Decreased ROS levels and NF-kappa B activation were likely to result from GSHPx increment since these phenomena were no longer observed when GSHPx activity was reduced by selenium depletion. The cellular contents of the two NF-kappa B subunits (p65 and p50) and of the inhibitory subunit I kappa B-alpha were unaffected by GSHPx overexpression, suggesting that increased GSHPx activity interfered with the activation, but not the synthesis or stability, of Nf-kappa B. Nuclear translocation of NF-kappa B as well as I kappa B-alpha degradation were inhabited in GSHPx-overexpressing cells exposed to oxidative stress. Moreover, in control T47D cells exposed to TNF alpha, a time correlation was observed between elevated ROS levels and I kappa B-alpha degradation. We also show that, in growing T47D cells, GSHPx overexpression altered the isoform composition of I kappa B-alpha, leading to the accumulation of the more basic isoform of this protein. GSHPx overexpression also abolished the TNF alpha-mediated transient accumulation of the acidic and highly phosphorylated I kappa B-alpha isoform. These results suggest that intracellular ROS are key elements that regulate the phosphorylation of I kappa B-alpha, a phenomenon that precedes and controls the degradation of this protein, and then NF-kappa B activation.