The relationship of erythrocyte glutathione peroxidase to blood selenium in swine

The erythrocyte glutathione peroxidase activity and blood selenium have been investigated in swine fed a Se deficient diet with, and without, selenium supplementation. A highly significant correlation (r = 0.90) between erythrocyte glutathione peroxidase and blood selenium was found.     

The effects of dietary oxidized fat and selenium source on performance,glutathione peroxidase,and glutathione reductase activity in broiler chickens

Normal or elevated selenium status of broilers, which is influenced by dietary selenium sources, improves the bird’s ability to overcome the adverse effects of reactive oxygen metabolites. The objective of this study was to evaluate the effects of feeding graded levels of peroxidized poultry fat on blood and hepatic glutathione peroxidase (GSH-Px), and hepatic glutathione reductase activity in broiler chickens fed either inorganic sodium selenite (SEL) or organic selenium enriched in the organic selenium yeast product Sel-Plex (SP). Nine starter diets, varying in levels of oxidized fat (0, 3, and 6 mEq/kg) and dietary selenium sources, were fed to 360 male chicks from hatch to 21 d of age. Sel-Plex or SEL was added to the basal diet to provide either 0 or 0.2 ppm of supplemental selenium in the diets. Blood and hepatic samples were obtained for each treatment group at 21 d of age. Neither peroxidized fat nor selenium source significantly altered the activity of hepatic glutathione reductase (P ≤ 0.05). Blood GSH-Px was influenced significantly by both fat and selenium source (P ≤ 0.05), but the fat × selenium source interaction was not significant (P ≥ 0.3). A selenium source effect on the hepatic GSH-Px activity (P ≤ 0.05) was evidenced by higher GSH-Px activity, even in the basal diet with no added peroxidized fat. An increase in GSH-Px activity was seen in the erythrocyte and hepatic samples in both the SEL and SP treatments when peroxidized fat was given at 3 mEq/kg, but in the erythrocytes and in the hepatic tissues from SEL-supplemented birds, there was an apparent inhibition of GSH-Px activity. This inhibition was not seen in the hepatic tissue samples from SP-fed birds. Because elevated GSH-Px activity is indicative of oxidative stress, it was concluded that dietary SP supplementation resulted in better selenium and redox status in broilers than did SEL. These results indicate that the dietary selenium supplied in an organic form (selenium yeast as SP) improved the selenium and redox status in broilers, leading to greater resistance to oxidative stress than when the inorganic form of selenium (SEL) was fed.     

不同硒水平对生长育肥猪血液生化指标的影响

试验研究了宁夏常用饲料中不同硒水平对生长育肥猪血液生化指标的影响。结果表明 :(1 )谷胱甘肽过氧化物酶 (GSH PX)活性随饲粮硒水平的增加 ,呈现下降 上升 下降的动态变化趋势。谷胱甘肽硫转移酶可反映缺硒的程度。 (2 )缺硒组仔猪血硒含量和全血中GSH PX均处于缺硒边缘状态 ,在临界值以下 ,不能满足仔猪的代谢需要。 (3)随饲粮硒水平的逐渐增加 ,猪瘟的抗体水平和淋巴细胞转化率明显升高 ,以饲粮中添加硒 0 45mg/kg时达到最高 ,仔猪发病率最低     

硒的生化特性与谷胱甘肽系统

介绍了硒的生理生化特性,重点阐述了硒与谷胱甘肽系统在抗氧化防御体系中的作用以及硒蛋白的研究进展。硒和谷胱甘肽(GSH)系统在氧化防御反应中起着关键性作用。其中GSH的主要功能是直接阻断氧化物生成和促进抗氧化物生成的还原反应;此外,GSH在代谢、细胞信号传导和蛋白质间相互作用中也具有辅助性功能,还可调节机体防御反应。硒在哺乳动物细胞中的保护作用受含硒氨基酸如硒半胱氨酸、硒蛋氨酸的调控。谷胱甘肽过氧化物酶(GSH-Px)的活性位点含有硒半胱氨酸残基。其它含硒蛋白(如硒蛋白P和硫氧还蛋白还原酶)也具有抗氧化特性。合成的有机硒复合物(如Ebselen)在机体氧化应激中是一种极具应用前景的抗氧化剂。硒蛋白和有机硒复合物在预防过亚硝酸盐的生成中也起着重要作用。     

Combined Therapeutic Effect of Dietary Selenium and Vitamin Ε on Manifested Vesd Syndrome in Weaned Pigs

By using a therapeutic dietary supplementation in pigs, which had developed the vitamin Ε and selenium deficiency (VESD) syndrome, the same amounts of α-tocopheryl acetate and selenium were found to be effective as under prophylactic conditions. The experiment thus supported the conclusions that the addition of 5 mg DL-α-tocopheryl acetate/kg and 135 μg selenium/kg to a diet, which contained only traces of vitamin Ε and selenium, represents a level of minimal requirement. Glutathione peroxidase activity in blood serum was used to evaluate the selenium status in pigs. A modified method for determination of tocopherol in fat tissue was described. The addition of 15 mg α-tocopheryl acetate/kg diet was demonstrated to be sufficient to maintain the tocopherol stores in body fat at an unchanged level.     

The stability of glutathione peroxidase activity in plasma from cattle,pigs and sheep on storage in the presence and absence of glutathione

Ovine, bovine and porcine plasma glutathione peroxidase (GSH-Px) activity decreased on storage at both 4°C and 20°C. The ovine and bovine enzymes were significantly less stable than the porcine enzyme. The addition of GSH to a final concentration of 2 mmol/L to plasma samples at the commencement of storage retarded the loss of both ovine and bovine plasma GSH-Px activity. The ovine enzyme was unique in that after inactivation by storage at 4°C, incubation with GSH restored the enzyme activity. It is recommended that plasma GSH-Px should be assayed fresh, or otherwise stored at –20°C.     

Bioavailability to chicks of selenium in barley, oats and meat meal

Day-old White Leghorn chicks deficient in selenium (Se) were fed a low Se basal diet (containing adequate level of vitamin E) for 2 weeks depletion period before they were given the experimental diets containing different levels of Se for 4 weeks. Dietary treatments contained 0.03, 0.06, 0.09 or 0.12 mg Se/kg as sodium selenite, barley, oats, meat meal or their extracted counterparts. Plasma GSH-Px activity was observed at weekly intervals, while the Se concentration of plasma and liver were determined at the end of the study. The biological availability of Se in the test ingredients was measured by the induction of plasma GSH-Px activity. In comparison to sodium selenite (100 %) it was: 77 % for barley, 80 % for extracted barley, 37 % for oats, 62 % for extracted oats, 20 % for meat meal, and 26 % for extracted meat meal. Using the retention of Se in plasma as a criterion, the following biological availability of Se was observed: barley 151 %; extracted barley 102 %; oats 90 %; extracted oats 107 %; meat meal 40 %; and extracted meat meal 47 %. Similarly, the efficiency of the test ingredients in increasing the Se concentration in liver was: barley 82 %; extracted barley 90 %; oats 67 %; extracted oats 98 %; meat meal 26 %; and extracted meat meal 31 %. The greater biopotency of the natural Se sources for increasing the Se concentration of the chick tissues than for inducing the plasma GSH-Px activity in comparison to sodium selenite, indicated that proportionally less amounts of the Se retained in the chick plasma from the natural sources were incorporated into the metabolic active form of Se, i.e., GSH-Px. Therefore, the plasma GSH-Px activity was suggested as the more reliable criterion to be used for the evaluation of the bioavailability of Se.     

Effect of selenium on performance, serum selenium concentration and glutathione peroxidase activity in pigs

Pigs from sows fed a diet deficient in Se and low in vitamin E were fed a Torula yeast diet supplemented with 100 IU dl-alpha-tocopheryl acetate/kg of diet. Dietary treatments were levels of supplemental Se of 0, .025, .050, .075 or .100 ppm. Some death loss occurred in pigs receiving no supplemental Se at approximately 5 wk of age. Autopsy revealed liver and heart lesions typical of vitamin E-Se deficiency. Selenium supplement had no significant effect on average daily gain, feed intake or gain to feed ratio for the 4-wk experiment. Selenium status of pigs was determined by serum Se concentration and serum glutathione peroxidase (GSH-Px) activity. Serum Se increased linearly (P less than .01) with increasing supplemental Se. Serum GSH-Px activity increased linearly (P less than .01) and quadratically (P less than .05) with increasing supplemental Se. With time, the level of serum Se and GSH-Px activity decreased in unsupplemental pigs, but increased in pigs fed diets supplemented with Se and resulted in significant interactions (P less than .01) between dietary Se level and time on experiment. The correlation between serum Se concentration and GSH-Px activity was .81 (P less than .01).     

The levels of selenium and glutathione peroxidase activity in blood of sheep, cows and pigs.

The levels of selenium (Se) and glutathione peroxidase (GPX) in the blood of sheep, cows and pigs under farm conditions were examined. Sheep appear to form two distinct groups, namely high Se and GPX and low Se and GPX. The high group gave ranges of 133-249 ng/ml and 77-179 iu/g Hb for blood Se and GPX respectively, while the low group showed levels of 21-67 ng/ml and 2-20 iu/g Hb. Overall sheep blood showed a high correlation between Se and GPX (r = 0-92, P less than 0-001). Cow bloods formed one group, all having low Se and GPX levels except for a single outlier. Omitting this animal, the overall ranges were 9-72 ng/ml and 6-36 iu/g Hb for Se and GPX respectively. Blood Se and GPX activity were significantly correlated (r = 0-59, P less than 0-001). Pigs formed a single group also, with the difference that while their blood Se was high, the corresponding blood GPX activities were relatively low. Overall ranges were 93-193 ng/ml and 17-69 iu/g Hb for Se and GPX respectively. Correlation between blood Se level and GPX activity in this species was not significant (r = 0-27, P more than 0-1).     

Serum glutathione peroxidase activity reflects short-term increases in selenium intake in goats

The objective of this study was to determine if serum glutathione peroxidase activity reflects short-term changes in the selenium status of goats. Angora goat kids (n=14) were fed pelleted luceme containing 20 microg/kg of selenium, and treated orally with either selenium (0.1 mg/kg of liveweight weekly, as sodium selenate) or de-ionised water. Serum activity of glutathione peroxidase was increased in response to supplementation and differed from that of controls within 24 hours of supplementation. The change in serum glutathione peroxidase activity during the 21 days after the start of weekly supplementation closely followed changes in serum selenium concentration. The results of this study suggest that serum glutathione peroxidase activity reflects the short-term improvement in the selenium status of Angora goat kids following oral supplementation with sodium selenate.     

Seasonal variation of selenium status of Norwegian dairy cows and effects of selenium supplementation

Blood selenium levels were found to fluctuate throughout the year, being highest during the indoor season when the greatest amounts of compound concentrates were fed. From October to January the average blood selenium levels increased from 0.10 μg/ml to 0.18 μg/ml (15 cows). Subcutaneous injections of barium selenate (500 mg selenium) increased the blood selenium levels significantly. The treated group (15 cows) reached average levels of about 0.21 μg/ml blood during the indoor season.The effect of oral supplementation of sodium selenite (for 2 months) on the levels of plasma selenium, blood selenium and glutathione peroxidase activity was investigated. Plasma selenium was found to give an immediate reflection of the daily selenium intake. Maximum activity of glutathione peroxidase was reached 1 month after the end of the supplementation period.It is concluded that if selenium enriched concentrates are used in a normal feeding regimen, further supplementation with selenium does not seem to be necessary.     

Comparative effect of selenium in wheat, barley, fish meal and sodium selenite for prevention of exudative diathesis in chicks

Groups af White Leghorn chicks obtained from dams deprived on selenium (Se), were fed from hatching a low-Se-vitamin E basal diet alone, or supplemented with 0.02, 0.04, 0.06 or 0.08 mg Se/kg diet, as sodium selenite (Na2SeO₃ · 5H₂O), wheat, barley or fish meal. Prevention of the Se-vitamin E deficiency responsive disease exudative diathesis (ED) as it was clinical observed, induction of the plasma Se dependent enzyme glutathione peroxidase (GSH-Px) activity, and Se concentration in the cardiac muscle were observed to be dietary Se level and source dependent. Slope ratio assay was applied to estimate the biological availability of Se in the natural sources relative to Se in sodium selenite. For the prevention of ED, the bioavailability of Se in wheat, barley and fish meal was 99, 85 and 80 %, respectively. The increase in the plasma GSH-Px activity revealed a bioavailability for Se in wheat, barley and fish meal of 79, 71 and 66 %, respectively. Using retention of Se in the cardiac muscle as the bioassay, a bioavailability of 108, 87 and 100 % was calculated for wheat, barley and fish meal Se, respectively.     

Estimation of the selenium requirement of growing guinea pigs (Cavia porcellus)

The aim of the study was to determine the selenium (Se) requirement of guinea pigs as a species unable to synthesize ascorbic acid. Forty-nine male guinea pigs (average weight 208 ± 3.5 g) were divided into an initial status group and six experimental groups. The animals received a Se deficient Torula yeast based basal diet (<0.02 mg Se and 26 mg α-tocopherol/kg) or a Se addition of 0.05, 0.10, 0.15, 0.20 and 0.25 mg/kg diet as sodium selenate for 10 weeks. There was no significant difference in weight gain (final weight 643 ± 21 g) between the groups and no clinical symptoms of Se deficiency occurred. With the exception of the testes, there was an increasing Se concentration in liver, plasma and haemolysate dependent on supplementation level. Glutathione peroxidase was determined in the plasma and Se dependent glutathione peroxidase (GPx1) in haemolysate, liver, kidney, heart and lung. Thioredoxin reductase (TR) activity was measured in liver, kidney and heart and deiodinase activity in the liver. A phospholipid hydroperoxide reducing activity with Se influence was determined in liver, kidney, heart, testes and brain. With the exception of GPx1 activity in heart and haemolysate and TR activity in the kidney, all enzymes already reached their maximal activity at 0.05 mg Se/kg diet. The activities of GPx1 and TR were used as parameters for broken line analysis and a Se requirement of 0.080 mg Se/kg diet was derived as sufficient for growing guinea pigs adequately supplied with vitamin E.     

Comparison of selenium levels and glutathione peroxidase activity in bovine whole blood.

Blood glutathione peroxidase activity and selenium levels were found to correlate well, indicating that glutathione peroxidase activity can be used to assess blood selenium levels in beef cattle. The glutathione peroxidase activity of blood is less stable than is the selenium concentration but when blood was stored at 4 degrees C, the glutathione peroxidase activity remained constant for seven days.     

不同硒水平对生长育肥猪生产性能的影响

试验研究了宁夏常用饲粮中不同硒水平(添加硒0，0．15，0．30，0．45，0．60mg／kg)对生长育肥猪生产性能的影响。结果表明：(1)在饲粮中添加不同水平的硒，对各个饲养阶段生长育肥猪的日增重、日采食量和饲料报酬没有明显影响。但从全期来看。饲粮中添加硒0．30mg／kg时日增重最高。料重比最低。(2)综合肉质品质各项指标的测定结果。饲粮中添加硒0．30，0．45，0．60mg／kg时，肌肉保水性、嫩度较好。以饲粮中添加硒0．30mg／kg时为最好。补硒组肉色评分、肌肉新鲜度和抗应激能力均较缺硒组高，肉色评分以饲粮中添加硒0．30mg／kg时最为理想。(3)在宁夏缺硒地区的玉米-豆粕、胡麻饼型饲粮中。从满足正常生长发育的代谢需要、改善肉的品质及降低发病率等方面综合考虑。在15～90kg体重的生长育肥猪基础饲粮中建议添加0．30mg／kg硒为宜，饲粮硒水平为0．33mg／kg，特别是在15～30kg体重的仔猪阶段。从降低发病率的角度考虑。硒的添加量可适当提高。     

Distribution of glutathione peroxidase activity and selenium in the blood of dairy cows.

The distribution of glutathione peroxidase (GSH-Px) activity and selenium concentrations among several components in the blood of dairy cows was examined. Approximately 98% of the GSH-Px activity in peripheral blood was associated with the erythrocytes when enzyme activity was expressed as units per milliliter of blood. The GSH-Px activity expressed per cell was approximately fourfold greater for peripheral leukocytes than for erythrocytes. The cellular component contained a greater proportion (approx 73%) of whole blood selenium than did the plasma. A positive linear relationship (r = 0.958) between blood GSH-Px activity and blood selenium concentrations was found in dairy cattle under practical field conditions.     

The influence of dietary selenium levels on blood levels of selenium and glutathione peroxidase activity in the horse

Twenty mature geldings, averaging 535 kg, were used to determine the influence of dietary selenium (Se) on the blood levels of Se and Se-dependent glutathione peroxidase (SeGSH-Px) activity in the horse. Horses were randomly assigned within breed to four treatments consisting of five horses each and fed a basal diet containing .06 ppm of naturally occurring Se. Diets were supplemented with .05, .10 and .20 ppm Se, as sodium selenite. Blood was drawn for 2 wk before, and for 12 wk following, the inclusion of supplement Se in the diets. Whole blood and plasma Se concentrations and plasma SeGSH-Px activities were determined from all blood samples. Selenium concentrations in plasma and whole blood increased linearly from wk 1 to wk 5 and 6, respectively, in Se-supplemented horses. After these times, no significant changes in Se concentration were observed in Se-supplemented or in unsupplemented horses throughout the remainder of the 12-wk trial. Plasma Se reached plateaus of .10 to .11, .12 to .14, and .13 to .14 micrograms/ml in horses supplemented with .05, .10 and .20 ppm Se, respectively. Whole blood Se reached plateaus of .16 to .18, .19 to .21, and .17 to .18 micrograms/ml in horses supplemented with .05, .10 and .20 ppm Se, respectively. Plasma SeGSH-Px activity was not significantly affected by dietary treatment. Therefore, this enzyme was not a good indicator of dietary Se in these mature horses.     

Serum selenium concentrations and glutathione peroxidase activities in cattle grazing forages of various selenium concentrations

In cows from 15 dairy herds (n = 210), serum selenium (Se) concentrations ranged from 0.021 to 0.789 microgram/ml, whereas 0.05 to 0.40 microgram/ml is the reported range for adequate serum Se concentrations in cattle. Serum Se concentrations of dairy cattle appeared to follow a geographic distribution pattern. On the basis of herd mean serum Se concentrations, adequate serum Se concentrations were found in cattle from only 1 of 5 herds grazing forage in the geographic area classified as Se deficient for cattle. Adequate mean serum Se concentrations were found in cattle from 4 of 5 herds located in geographic areas described as having variable forage Se concentrations (Se-marginal areas). Of the 10 herds from these 2 areas, there were only 2 herds in which 95% of the cattle had serum Se concentrations in the Se-adequate range (0.05 to 0.40 microgram/ml). In 2 selected neighboring farms in the Se-deficient area, cattle in 1 herd had adequate serum Se concentrations and cattle in the other herd had less than adequate serum Se concentrations (less than 0.05 microgram/ml). Therefore, more cattle are at risk of developing Se-deficiency disease than is commonly believed and forage of neighboring farms may have different Se concentrations. Serum Se concentrations (up to 0.789 microgram/ml) correlated with glutathione peroxidase enzyme activity; this serum Se concentration (0.789 microgram/ml) is approximately 6.2 times higher than previously reported in dairy cattle. Therefore, RBC glutathione peroxidase activity may be useful in determining the diagnosis of chronic Se toxicosis.     

Relationship between blood selenium concentration or glutathione peroxidase activity, and milk selenium concentrations in New Zealand dairy cows

AIM: To determine the relationships between blood selenium (Se) concentrations or glutathione peroxidase activity (GSH-Px), and milk Se concentrations in dairy cows. METHODS: Seventy-two Friesian dairy cows were either untreated or injected with 0.5, 1.0 or 2.0 mg Se/kg liveweight as barium selenate (BaSeO4) formulations, resulting in 6 groups of animals with mean blood Se concentrations that varied from 212 to 2272 nmol/l. Milk samples were collected on Days 104 and 188, and blood samples were collected prior to treatment and on Days 41, 76, 104, 188, 244, and 292 after Se injection. RESULTS: Significant quadratic relationships between blood Se and milk Se concentrations, as well as blood GSH-Px activity and milk Se concentrations, were evident at Days 104 and 188. Using combined data, these were represented by the equations: milk Se = 27.3 + 0.073 blood Se -0.00001 (blood Se)2; R2=0.79, p<0.005, and; milk Se = 34.8 + 4.99 GSH-Px -0.068 (GSHPx)2; R2=0.79, p<0.005. CONCLUSIONS: The Se status of dairy cows can be assessed from milk Se concentrations. CLINICAL SIGNIFICANCE: Bulk-tank milk Se concentrations could be evaluated as a method to assess the Se status of dairy herds.