Se Glutathione Peroxidase Activity Research Articles

Effects of Selenium Supplementation in Patients with Mild Cognitive Impairment or Alzheimer’s Disease: A Systematic Review and Meta-Analysis

Elevated levels of oxidative stress could cause and aggravate Alzheimer’s disease (AD). Selenium (Se) is a trace element with antioxidant and anti-inflammatory activity with neuroprotective effects. To evaluate the effects of Se supplementation in patients with AD or mild cognitive impairment (MCI) through a systematic review and meta-analysis, data were searched and collected from four electronic databases, including clinical trial studies published until December 2020, following the PRISMA guidelines. Statistical analysis was performed by RevMan, and the risk of bias was assessed using the Rob 2 tool. A total of 1350 scientific papers were collected, and following evaluation 11 papers were included in the systematic review and 6 of these were used in the meta-analysis. Studies that evaluated only Se supplementation observed an improvement in Se levels, glutathione peroxidase (GPX) activity, and in some cognitive tests in MCI patients; similarly, improvement in Se levels and mini-mental score was also observed in AD patients. Regarding supplementation of Se plus other nutrients, improvement in cognitive tests was observed in both AD and MCI patients. Therefore, Se supplementation is a good alternative for patients with AD and MCI for improving Se levels and GPX activity. More detailed studies are required to further evaluate the effects of Se on the cognitive deficit and oxidative stress associated with AD and MCI.

Metabolic syndrome during gestation and lactation: An important renal problem in dams. selenium renal clearance

BackgroundMetabolic syndrome (MS) in lactating dams leads to several cardiometabolic changes related to selenium (Se) status and selenoproteins expression which produce hypertension. However, little is known about the state of these dams’ kidney functions and their Se deposits. MethodsTwo experimental groups of dam rats were used: control (Se: 0.1 ppm) and MS (Fructose 65 % and Se: 0.1 ppm). At the end of lactation (21d postpartum) kidney weight and protein content, Se deposits, and the activity of the antioxidant selenoprotein glutathione peroxidase (GPx) were measured in dams. Kidney functional parameters: albuminuria, creatinine clearance, serum aldosterone and uric acid levels and water and electrolyte (Na+ and K+) balance were also evaluated. Systolic blood pressure (SBP) was measured. ResultsIn MS dams at the end of lactation Se deposits and GPx activity are higher in the kidney; however, lipid renal peroxidation appears, relative Se clearance increases, and the dams have lost Se by urine. MS dams have polyuria and polydipsia, high uric acid serum levels, albuminuria and high creatinine clearance, implying glomerular renal malfunction with protein loss. They also present hypernatremia, hypokalemia and hyperaldosteronemia, leading to high SBP; however, a natriuretic process is taking place. ConclusionSince these alterations appear, at least in part, to be related to oxidative stress in renal cells, Se supplementation could be beneficial to avoiding greater lipid renal oxidation during lactation.

Alternative selenium supplement for sheep

This study investigated Se-dependent parameters in ewes after supplementation with an experimental Se product (P-Se) in comparison to sodium selenite. Six Dorset ewes averaging 93.0 (SE = 2.5) kg initial body weight were used in a replicated 3 × 3 Latin square design experiment balanced for residual effects. The study began with a 2-wk background, low-Se period and had 3 experimental periods of 3 weeks each, with 2-wk washout periods between them. The treatments studied were: (1) unsupplemented control (basal diet containing 0.065 mg Se/kg dry matter, DM); (2) basal diet supplemented with Na-selenite providing 0.25 mg Se/kg DM; and (3) basal diet supplemented with P-Se (containing 29 % Na-selenite and 71 % amorphous elemental Se) providing 0.27 mg Se/kg DM (P-Se). Blood samples (taken from the jugular vein) and spot urine and fecal samples were collected the day before the start of each experimental period, on the last day of each washout period, and once weekly during the experimental periods for analysis of Se concentration and glutathione peroxidase (GPx) activity (blood plasma only). Ewes supplemented with P-Se and Na-selenite had increased (P < 0.001) plasma Se concentration compared with ewes fed the control diet. Absolute concentration of Se in plasma was greater (P < 0.001) for ewes fed Na-selenite (80.9 μg/L) than for ewes fed P-Se (72.3 μg/L). Absolute plasma GPx activity was greater (P < 0.001) for ewes fed Na-selenite and P-Se compared with the control, but was not different between the Se treatments. Concentration of Se in fecal matter was greater (P < 0.001) for both Se sources than the control and fecal Se concentration was higher (P < 0.001) for P-Se compared with Na-selenite. Absolute Se concentration in urine was greater (P ≤ 0.003) for Na-selenite than the control and P-Se. Selenium supplementation of ewe diet increased Se concentration and GPx activity in blood plasma, regardless of Se source. Although P-Se had slightly inferior absorption, compared with Na-selenite, our data indicate that it can potentially be an effective source of dietary Se for mature ewes, but further studies are needed to confirm these results in other farm animal species and physiological stages.

Platelet Selenium Indices as Useful Diagnostic Surrogate for Assessment of Selenium Status in Lambs: an Experimental Comparative Study on the Efficacy of Sodium Selenite vs. Selenium Nanoparticles.

Unlike in human medicine, information on the platelet selenium (Se) concentration and glutathione peroxidase (GPx) activity, as potential biomarkers of Se status, is lacking in the field of veterinary medicine. The aims of this study were to compare the effects of sodium selenite (SeS) and Se nanoparticles (SeN) on platelet Se indices, and compare the results with those of conventional indices of Se status in sheep. Eighteen lambs with marginal Se status were assigned to a control (CON) group and two Se-treated groups administered either a single dose of Se at 0.055mg/kg BW subcutaneously as SeS or SeN. The Se concentration and GPx activity in plasma, erythrocytes, whole blood, and platelets were assessed at 14 time points during 90days. In Se-treated groups, Se concentrations and GPx activity increased significantly in plasma, whole blood, erythrocytes, and platelets. However, the responses in SeS group often started and peaked earlier and, in almost all time points, were more pronounced than the SeN group (P < 0.001), indicating that SeS compared to SeN was more biopotent in raising Se biomarkers. Se indices in platelets started and peaked later than those of short-term (in plasma) and earlier than those of long-term indices (in erythrocytes) indicating that platelet indices can serve as intermediate-term biomarkers of Se status. In conclusion, platelet indices of Se are promising proxy for currently used indices of Se status in sheep, regardless of Se source.

Is maternal dietary selenium intake related to antioxidant status and the occurrence of pregnancy complications?

Selenium (Se) is a trace element essential for the appropriate course of vital processes in the human body. It is also a constituent of the active center of glutathione peroxidase and other antioxidant compounds which play an important role in red-ox processes. Associations between lower blood selenium concentration and obstetric complications has been reported in many studies. The aim of this study was to determine the dietary selenium intake and serum selenium content in pregnant Polish women and relate this to antioxidant status as whole blood glutathione peroxidase (GPX) activity, serum uric acid (UA) content and serum total antioxidant status (TAS) and pregnancy complications occurrence. Ninety-four pregnant women at a mean age 30.6 ± 5.4 years from the Lower Silesia region of Poland were recruited to the study, 37% of studied group had pregnancy complications. The mean reported Se intake and serum selenium content for Polish pregnant women was in the first trimester – 53.99 μg/day and 44.36 μg/l, the second trimester – 58.93 μg/day and 43.16 μg/l and the third trimester – 62.89 μg/day and 40.97 μg/l, respectively. Selenium intake below or above recommended value hadn’t significant effect on GPX activity, TAS and UA levels. There were no statistical differences in selenium intake, serum selenium content, GPX activity and TAS and UA level between physiological and complicated pregnancy, but a positive correlation between Se intake and serum selenium content was observed during all period of gestation as well as in the second trimester of pregnancy between Se intake and GPX activity in group with physiological pregnancy where selenium intake was below the recommended level. Selenium intake above the recommended level was positively correlated also with serum UA level in first and second trimester of pregnancy. Despite weak, positive correlations in the first two trimesters of pregnancy between selenium supply and GPX activity and UA concentration we concluded that selenium intake does not significantly affect during pregnancy, both: markers of the antioxidant status of pregnant women and the occurrence of pregnancy complications.

Fructose exposure during gestation and lactation altered hepatic selenoprotein expression, oxidative balance and metabolic profile in female rat pups

Fructose-rich diets, an experimental model of induced metabolic syndrome (MS), affects pregnant and lactating rat dams, and moreover, it leads to an imbalance in their offspring’s metabolic profile. Selenium (Se) homeostasis and body distribution is also altered. Selenoproteins: Glutathione peroxidase (GPx) and selenoprotein P (SelP) appear to play a role in MS. To evaluate selenoproteins’ implication in the transmission of this pathology to the progeny, hepatic Se deposits, GPx activity, biomolecular oxidation and selenoproteins and AMPK expression were measured in the offspring of dams exposed to a fructose-rich diet (65%). Se intake and liver selenoproteins are affected by fructose exposition during early nutrition. Female fructose pups show a repletion of Se and oxidation in liver, higher GPx activity and expression of hepatic GPx1 and SelP, related to a lower activation of AMPK and serum insulin levels. Fructose exposure during early nutrition negatively alters selenoproteins, oxidation and metabolism in female pups.

Maternal ethanol consumption reduces Se antioxidant function in placenta and liver of embryos and breastfeeding pups

AimThe fetal alcohol exposition during pregnancy leads to different disorders in offspring, related to the oxidative stress generated by alcohol. It is well-documented that there is an impairment of the antioxidant selenoprotein Glutathione peroxidase (GPx) activity in ethanol offspring during the embryo period, although no-one has described Selenium (Se) status. The aim is to analyze for the first time Se deposits in vivo and Se's biological implication in embryos and placenta after alcohol exposure and in offspring whose mothers continued to drink ethanol during lactation. Materials and methodsSe deposits, GPx and glutathione reductase (GR) activity, lipid and protein oxidation and the expression of GPx1 were measured in placenta and liver of both embryos (E-19) and breastfeeding pups (L-21) in control and ethanol groups (20% v/v). Key findingsEthanol consumption decreased Se deposits, GPx activity and GPx1 expression, while increasing biomolecular oxidation in placenta and in the liver of E-19 and L-21. The GR/GPx ratio decreased in placenta and in E-19, together with an increase in lipid oxidation, while increased in the liver of L-21 pups with protein oxidation. Ethanol also decreased the GPx1 expression/GPx activity ratio in the liver of E-19 and L-21, indicating that alcohol decreases GPx activity by both depleting Se deposits and promoting GPx inactivation. In placenta GPx activity is proportional to the GPx1 expression found, so the ethanol affects GPx activity in offspring more than in dams. SignificanceTherefore, Se supplementation therapy in dams could contribute as an interesting antioxidant that prevents fetal alcohol syndrome.

Effects of Selenium Supplementation on the Diabetic Condition Depend on the Baseline Selenium Status in KKAy Mice.

Oxidative stress in obesity leads to insulin resistance in type 2 diabetes. Some selenoproteins possess antioxidant properties, suggesting that selenium (Se) may protect against type 2 diabetes; however, evidence from epidemiological studies is contradictory. We hypothesized that Se status before supplementation (baseline) contributes to the supplementation outcome. This study aimed to clarify the influence of baseline Se status on the effect of Se supplementation on the diabetic condition. Six-week-old KKAy mice were fed a diet without supplemental Se or with 0.1ppm Se in the form of L-selenomethionine (SeM) for 2weeks to create low-Se and sufficient-Se baseline statuses, respectively. For the next 4weeks, low-Se mice were given a SeM (0.5ppm Se)-supplemented diet, and sufficient-Se mice were given either a SeM (0.5ppm Se)- or sodium selenite (0.5ppm Se)-supplemented diet; control groups continued on baseline diets. Serum Se concentrations, glutathione peroxidase (GPx) activities, adiponectin levels, glucose tolerance, and insulin sensitivity were analyzed. All mice became diabetic during the 2-week baseline induction period. At the end of the supplementation period, Se-receiving groups demonstrated significantly higher Se concentrations and GPx activities than their respective controls. Sufficient-Se mice receiving SeM had lower blood glucose levels and better insulin sensitivity than control and sodium selenite-receiving mice, whereas low-Se mice receiving SeM showed no such improvements compared with their controls. Our results suggest that Se supplementation in the form of SeM may help prevent type 2 diabetes aggravation in people taking the 55μg/day Se recommended dietary allowance.

Involvement of the Selenium Level in Plasma Glutathione Peroxidase Activity in Newly Diagnosed Patients with Graves’ Disease and Hashimoto Thyroiditis

Disturbed antioxidant enzymes activities was known to be associated to Auto-Immune Thyroid Diseases (AITD), but it is noteworthy that the selenoenzyme glutathione peroxidase (GPx) showed the lowest activity and a selenium (Se) deficiency may be the major cause. Most studies conducted on AITD are focused on the effect of the Se supplementation on the evolution of these pathologies. The aim of this study was to evaluate the Se level in plasma of Graves’ disease (GD) and Hashimoto Thyroiditis (HT) patients and its relationship with the redox status of these AITD. For this purpose, the Se levels as well as the GPx activity were evaluated in the plasmas of 33 patients with AITD. Results were compared with those of 27 healthy controls and among the two groups of patients. Results concerning GD and HT patients revealed lower Se levels by comparison with healthy controls (p&lt;0.01 and p&lt;0.05 respectively). Just like the Se, the GPx activity was found to be significantly lower in GD and HT patients compared to controls (p&lt;0.01, p&lt;0.001 respectively). The comparison between AITD groups showed higher Se level for the HT group (p&lt;0.05), whereas, no significant differences were noted for the GPx activity. The correlation study showed positive correlation between Se level and GPx activity in HT group (r=0.64, p&lt;0.01); and negative correlations between Se and anti-thyroglobuline and anti-Thyroid Stimulating Hormone Receptor levels in GD group (r= -0.71, p&lt;0.05 and r= -0.73, p&lt;0.05 respectively). As a conclusion, our findings have shown that the Se deficiency may be involved in the redox misbalance in HT; further investigations are mandatory to elucidate the origin of the reduced GPx activity in GD patients.

EFFECT OF SELENIUM SUPPLEMENTATION VIA BRAZIL NUT (BERTHOLLETIA EXCELSA, HBK) ON THYROID HORMONES LEVELS IN HEMODIALYSIS PATIENTS: A PILOT STUDY.

thyroid function depends on trace mineral selenium (Se), being at the active center of the iodothyronine deiodinase that catalyzes the conversion of the thyroxine (T4) to the active form of thyroid hormone, triiodothyronine (T3). Hemodialysis (HD) patients have reduced T3 levels partly due to impaired hormonal conversion that can be related to Se deficiency, a common feature in these patients. This study evaluated the effect of Brazil nuts (richest Se source) on thyroid hormone levels in HD patients. we performed an uncontrolled intervention with 40 HD patients (53.3 ± 16.1 yrs, dialysis vintage 62.0 (8.0 - 207.0) months) that received one nut (≈5g, average 58.1 μg Se/g) per day for three months. Se plasma levels were determined by atomic absorption spectrophotometry with hydride generation and, serum T3, free T4 (FT4), TSH as well as glutathione peroxidase (GPx) activity were measured by ELISA. all patients were Se deficient and presented low T3 levels at baseline. After intervention, Se plasma levels (from 17.6 ± 11.6 to 153.4 ± 86.1 μg/L), GPx activity (from 33.7 ± 5.9 to 41.4 ± 11.2 nmol/min/mL), T3 (from 27.3 ± 8.8 to 50.2 ± 4.8ng/dL) and FT4 levels (0.87 ± 0.2 to 0.98 ± 0.4 ng/dL) were significantly increased (p < 0.05), while TSH levels were reduced (from 2.17 ± 1.3 to 1.96 ± 1.1 uUI/mL), but not significantly. in conclusion, increasing Se levels via Brazil nut supplementation was associated with improvement in thyroid hormone levels in HD patients, although the amount of Se given was not able to restore T3 to normal levels.

The Level of Selenium and Oxidative Stress in Workers Chronically Exposed to Lead.

The possible beneficial role of selenium (Se) on the oxidative stress induced by lead (Pb) is still unclear in humans. Therefore, the aim of the present study was to explore the associations among the Se levels, chronic Pb exposure, oxidative stress parameters, and parameters characterizing the function of the antioxidant defense system in men who are occupationally exposed to Pb. Based on the median serum Se concentrations, the 324 study subjects were divided into two subgroups: a subgroup with a low Se level (L-Se) and a subgroup with a high Se level (H-Se). The levels of lead (PbB) and zinc protoporphyrin (ZPP) in the blood and the delta-aminolevulinic acid (ALA) level in the urine served as indices of Pb exposure. The PbB level was significantly lower in the H-Se group compared to that in the L-Se group by 6 %. The levels of 8-hydroxyguanosine and lipofuscin (LPS) and the activity of superoxide dismutase were significantly lower in the H-Se group compared to that in the L-Se group by 17, 19, and 11 %, respectively. However, the glutathione level (GSH) and the activities of glutathione peroxidase (GPx) and catalase were significantly higher by 9, 23, and 3 %. Spearman correlations showed positive associations between the Se level and GPx activity and GSH level. A lower serum Se level in chronically Pb-exposed subjects is associated with higher Pb blood levels and an elevated erythrocyte LPS level, which reflects the intensity of oxidative stress. Besides, in a group of Pb-exposed subjects with lower serum Se level, depleted GSH pool and decreased activity of GPx in erythrocytes were reported. However, the present results are inadequate to recommend Se supplementation for chronic lead exposure at higher doses than would be included in a normal diet except for selenium deficiency.

Cofactor metals and antioxidant enzymes in cisplatin-treated rats: effect of antioxidant intervention

We explored the association between the activities of antioxidant enzymes and their metallic cofactors in rats treated with cisplatin. The antioxidant effects of aminoguanidine, and a combination of vitamins E and C were investigated. Plasma platin was significantly lower than liver and kidney. Cisplatin treatment caused significant increase in plasma Se-glutathione peroxidase activity. Activities of Se-glutathione peroxidase, glutathione S-transferase, catalase and Cu,Zn-superoxide dismutase have been found to be significantly decreased in liver and kidney compared to controls. Zn levels in these organs were diminished upon cisplatin treatment, while levels of Cu were unaffected. Interestingly, levels of iron, the cofactor of catalase, were found to be significantly increased in liver and kidney. Intervention with aminoguanidine or vitamins was generally prevented cisplatin-caused changes in the activity of enzymes and in the tissue levels of cofactor metals. These observations suggest that relation between activities of enzymes and levels of cofactor metals is multifactorial.

Gene expression of porcine blastocysts from gilts fed organic or inorganic selenium and pyridoxine

In this study, we determined how maternal dietary supplementation with pyridoxine combined with different sources of selenium (Se) affected global gene expression of porcine expanded blastocysts (PEB) during pregnancy. Eighteen gilts were randomly assigned to one of the three experimental diets (n=6 per treatment): i) basal diet without supplemental Se or pyridoxine (CONT); ii) CONT+0.3 mg/kg of Na-selenite and 10 mg/kg of HCl-pyridoxine (MSeB610); and iii) CONT+0.3 mg/kg of Se-enriched yeast and 10 mg/kg of HCl-pyridoxine (OSeB610). All gilts were inseminated at their fifth post-pubertal estrus and killed 5 days later for embryo harvesting. A porcine embryo-specific microarray was used to detect differentially gene expression between MSeB610 vs CONT, OSeB610 vs CONT, and OSeB610 vs MSeB610. CONT gilts had lower whole blood Se and erythrocyte pyridoxal-5-P concentrations than supplemented gilts (P<0.05). No treatment effect was observed on blood plasma Se-glutathione peroxidase activity (P=0.57). There were 10, 247, and 96 differentially expressed genes for MSeB610 vs CONT, OSeB610 vs CONT, and OSeB610 vs MSeB610 respectively. No specific biological process was associated with MSeB610 vs CONT. However, for OSeB610 vs CONT, upregulated genes were related with global protein synthesis but not to selenoproteins. The stimulation of some genes related with monooxygenase and thioredoxin families was confirmed by quantitative real-time RT-PCR. In conclusion, OSeB610 affects PEB metabolism more markedly than MSeB610. Neither Se sources with pyridoxine influenced the Se-glutathione peroxidase metabolic pathway in the PEB, but OSeB610 selectively stimulated genes involved with antioxidant defense.

Selenium bioavailability from shrimps (Penaeus vannamei Boone) and its effect on the metabolism of phospholipid and cholesterol ester

We evaluated selenium bioavailability from shrimps, and its effect on the metabolism of phospholipid (PL) and cholesterol ester (CE) using a mouse model. Experimental mice were categorized into 4 groups received different doses of Se from shrimps for 4 consecutive weeks. It was calculated that the bioavailability of Se from shrimps was ∼86–88% based on the apparent absorption. Comparing with control group, Se content in tissues and Glutathione peroxidase (GPx) activities in liver and blood increased significantly from selenium supplemented groups. The lipidomics analysis showed that there was no difference in detectable total species of PLs and CE in intestine samples, but the total content and the relative percentage of PLs and CE increased proportionally to the dose of Se intake. The results indicate that selenium supplementation lead to an increase in tissue Se concentration and GPx activity as well as changes in intestine PLs and CE, species and abundance of individual lipid fractions.

Role of selenium and glutathione peroxidase on development, growth, and oxidative balance in rat offspring

Selenium (Se), an essential trace metal, is important in both growth and reproduction and is the constituent of different selenoproteins. The glutathione peroxidase (GPx) family is the most studied as it prevents oxidative stress. Liver oxidation is considered as another mechanism involved in low birth weight. Therefore, in order to ascertain whether GPx is related to the effects of Se on growth during gestation and lactation, three groups of rat pups were used: control, Se deficient (SD), and Se supplemented (SS). Morphological parameters and reproductive indices were evaluated. Hepatic Se levels were measured by graphite furnace atomic absorption while spectrophotometry was used for activity of antioxidant enzymes and oxidative stress markers in liver and western blotting for expression of hepatic GPx1 and GPx4. The SD diet increased mortality at birth; decreased viability and survival indices; and stunted growth, length, and liver development in offspring, thus decreasing hepatic Se levels, GPx, glutathione reductase, and catalase activities, while increasing superoxide dismutase activity and protein oxidation. The SS diet counteracted all the above results. GPx1 expression was heavily regulated by Se dietary intake; however, although Se dietary deficiency reduced GPx4 expression, this decrease was not as pronounced. Therefore, it can be concluded that Se dietary intake is intimately related to growth, length, and directly regulating GPx activity primarily via GPx1 and secondly to GPx4, thus affecting liver oxidation and development. These results suggest that if risk of uterine growth retardation is suspected, or if a neonate with low birth weight presents with signs of liver oxidation, it may be beneficial to know about Se status.

Distribution of Selenium and Oxidative Stress in Breast Tumor-Bearing Mice

The present study investigated the effects of breast tumors on the blood and tissue distribution of essential trace mineral selenium (Se), and oxidative stress status of mice. Female 10-week-old BALB/cByJNarl mice were randomly assigned into control (CNL) and breast tumor-bearing (TB) groups. TB mice were injected subcutaneously into the right hind thigh with 5 × 106 EMT6 mouse mammary tumor cells. After 22 days, we measured Se concentrations, Se-dependent glutathione peroxidase (GPx) activities, and malondialdehyde (MDA) products (indicator of oxidative stress) in plasma, various tissues, and plasma vascular endothelial growth factor (VEGF) concentrations. There were no significant differences in body weights and daily intake between both groups. Compared with the CNL group, TB mice have decreases in plasma Se concentrations and GPx activities, as well as higher plasma VEGF and MDA concentrations. Plasma Se concentrations were also negatively correlated with plasma MDA and VEGF concentrations. Furthermore, tissue Se concentrations and GPx activities in TB animals were lower; whereas the MDA concentrations higher in various tissues including liver, kidney, brain, lung, spleen, and thymic tissues. In conclusion, disruption of Se homeostasis critically reflects oxidative stress in target tissues, thus may increase the risk for progression of breast cancer and metastasis.

Glutathione Peroxidase 1 Pro198Leu Polymorphism in Brazilian Alzheimer’s Disease Patients: Relations to the Enzyme Activity and to Selenium Status

Background/Aims: Oxidative stress plays a central role in Alzheimer’s disease (AD). Pro198Leu cytosolic glutathione peroxidase (GPx1) polymorphism seems to be associated with a lower activity of this enzyme, but there are no studies with AD patients. Thus, the aim was to determine the frequency of the GPx1 Pro198Leu polymorphism in AD patients and to verify its relation to glutathione peroxidase (GPx) activity and selenium (Se) status. Methods: The study was carried out in a group of AD elderly (n = 28) compared to a control group (n = 29). Blood Se concentrations were measured through hydride generation atomic absorption spectroscopy. GPx activity was determined using a commercial kit, and the polymorphism using amplified DNA sequencing. Results: The distribution of genotypes was not different between groups. The variant allele frequency was 0.179 (AD group) and 0.207 (control group). Although no differences regarding GPx activity were found between individuals with different genotypes, lower blood Se levels were found in Pro/Pro AD patients compared to Pro/Pro control subjects, which was not found in the Pro/Leu groups. Moreover, the association between the erythrocyte Se concentration and GPx activity was affected by the Pro198Leu genotype. Conclusions: Results indicate that this polymorphism had apparently affected Se status in AD patients and that more studies in this field are necessary.

Effect of zinc supplementation on glutathione peroxidase activity and selenium concentration in the serum, liver and kidney of rats chronically exposed to cadmium

It was investigated whether the ability of zinc (Zn) to prevent cadmium (Cd)-induced lipid peroxidation may be connected with its impact on glutathione peroxidase (GPx) activity and selenium (Se) concentration. GPx and Se were determined in the serum, liver and kidney of the rats that received Cd (5 or 50mg/L) or/and Zn (30mg/L) in drinking water for 6 months in whose the protective Zn impact was noted (Rogalska J, Brzóska MM, Roszczenko A, Moniuszko-Jakoniuk J. Enhanced zinc consumption prevents cadmium-induced alterations in lipid metabolism in male rats. Chem Biol Interact 2009;177:142–52). Moreover, dependences between these parameters, and indices of lipid peroxidation (F2-isoprostane, lipid peroxides, oxidized low density lipoprotein cholesterol) as well as concentrations of Cd and Zn were estimated. The supplementation with Zn during the exposure to 5mg Cd/L entirely antagonized the Cd-induced increase in GPx activity and Se concentration in the liver and kidney, but not in the serum. Zn administration during the treatment with 50mg Cd/L totally or partially prevented from the Cd-caused decrease in GPx activity and Se concentration in the serum, liver and kidney. At the higher level of Cd exposure, GPx activity in the serum and tissues positively correlated with Se concentration. Moreover, numerous correlations were noted between GPx and/or Se and the indices of lipid peroxidation. The results indicate that the protective impact of Zn against the Cd-induced lipid peroxidation during the relatively high exposure might be connected with its beneficial influence on Se concentration and GPx activity in the serum and tissues, whereas this bioelement influence at the moderate exposure seems to be independent of GPx and Se.

Effect of Selenium-Enriched Probiotics on Laying Performance, Egg Quality, Egg Selenium Content, and Egg Glutathione Peroxidase Activity

A 35-day experiment was conducted to evaluate the effect of selenium-enriched probiotics (SP) on laying performance, egg quality, egg selenium (Se) content, and egg glutathione peroxidase (GPX) activity. Five hundred 58-week-old Rohman laying hens were randomly allotted to 5 dietary treatments of 100 each. Each treatment had 5 replicates, and each replicate had 5 cages with 4 hens per cage. The SP was supplemented to a corn-soybean-meal basal diet at 3 different levels that supplied total Se at 0.2, 0.5, and 1.0 mg/kg. The basal diet served as a blank control, while the basal diet with supplemental probiotics served as a probiotics control. The results showed that dietary SP supplementation not only increased (p < 0.05) the rate of egg laying, day egg weight, mean egg weight, egg Se content, and egg GPX activity but also decreased (p < 0.05) the feed:egg ratio and egg cholesterol content. The egg Se content was gradually increased (p < 0.05) along with the increasing level of dietary Se. The SP supplementation also slowed down (p < 0.05) the drop of Haugh units (HU) of eggs stored at room temperature. The egg GPX activity had a positive correlation (p < 0.01) with egg Se content and a negative correlation (p < 0.01) with egg HU drop. These results suggested that Se contents, GPX activity, and HU of eggs were affected by the dietary Se level, whereas the egg-laying performance and egg cholesterol content were affected by the dietary probiotics. It was concluded that this SP is an effective feed additive that combines the organic Se benefit for hen and human health with the probiotics benefit for laying hen production performance. It was also suggested that the eggs from hens fed this SP can serve as a nutraceutical food with high Se and low cholesterol contents for both healthy people and patients with hyperlipidemia, fatty liver, or cardiovascular disease.

Effect of Selenium Depletion on Oxidative Stress in Mature Horses

s / Journal of Equine Veterinary Science 31 (2011) 230-356 257 [5] Bryden WL. Amino acid requirements of horses estimated from tissue composition. Proc Nutr Soc 1991;16:53. [6] Wilson JA, Graham-Thiers PM. Muscle and plasma amino acids in pregnant/lactating mares and their weanling foals. J Equine Vet Sci 2009;29:370. [7] Nutrient Requirements of Horses. 6th ed. Washington, DC: The National Academies Press; 2007. [8] Waggoner JW, LOxest CA, Mathis CP, Hallford DM, Petersen MK. Effects of rumen-protected methionine supplementation and bacterial lipopolysaccharide infusion on nitrogen metabolism and hormonal responses of growing beef steers. J Anim Sci 2009;87:681. Effect of Selenium Depletion on Oxidative Stress in Mature Horses M. Brummer, S. Hayes, J.E. Earing, S.M. McCown, and L.M. Lawrence University of Kentucky, Lexington, KY, USA Introduction: Glutathione peroxidase (GPx) plays an important role in the neutralization of hydroperoxides andhydrogenperoxide. Hydrogen peroxide can generate hydroxyl radicals which are regarded as a very harmful reactive oxygen species [1]. Selenium (Se) deficiency can result in decreased GPx activity; therefore our aim was to investigate the effect of low Se status on oxidative stress in mature idle horses. We hypothesized that Se depletion would result in a decrease in GPx activity, serum total antioxidant capacity (TAC) and an increase in oxidative stress, measured as serum malondialdehyde concentration (MDA). Type I deiodinase, is a selenoenzyme responsible for the conversion of inactive T4 to active T3. Therefore as additional indicators of Se status we measured triiodothyronine (T3), thyroxine (T4), and the T3:T4 ratio as changes in these hormones or in their ratio has been evaluated in horses fed varying levels of Se before [2]. Materials and Methods: Twenty eight mature horses (6 24 yr) were used in this study. The 28 horses included 8 geldings and 20 mares that had resided on the farm for at least 60 days prior to the study. The study period was 28 wks. Horses were kept on pasture ( .05). MDA concentrationwas not different between AS and LS at the initial or final time point, howeverMDAdid increaseover time (P< .05) in LS (from3.40 .86 nmol/mL to 4.04 .89 nmol/mL) while it remained similar in AS (4.68 1.78 nmol/mL to 5.09 1.09 nmol/mL). Two traditional indicators of Se status were measured: whole blood Se concentration and GPx activity. In addition the serum T3/ T4 ratio was determined. Type I deiodinase, the enzyme responsible for converting T4 to T3, has a greater ranking in terms of priority of Se supply than cytosolic GPx [2]. A change in this ratio is generally not observed during a marginal Se deficiency [2], so the increased ratio of T3/T4 in the LS horses along with the changes in whole blood Se and GPx suggests that the LS horses were at, or approaching, deficient Se status. TAC was expected to decrease in LS horses, but it was unaffected. The lack of change in TAC may point towards a compensatory mechanism within the antioxidant system, or lack of sensitivity of the assay as a measure of the GPx-associated antioxidant capacity in serum. GPx is only one of several compounds that contribute to total antioxidant capacity. MDA is a byproduct of lipid peroxidation [4]. We hypothesized that MDA concentrations would increase with decreasing Se status. Although MDA concentrations increased over time in the LS horses, the magnitude of the changes were relatively small. Much larger changes in MDA have been reported in response to exercise or disease in other studies [4] and some type of oxidative challenge might be necessary to produce more marked differences in MDA in the horses studied here. Conclusion: In this study feeding a low Se diet for 28 wks altered indicators of Se status, but appears to have hadminimal effects on the indicator of oxidative damage. However, more marked effects might have been observed if the horses had been challenged with an oxidative stressor such as exercise or disease. Further research in this area may provide better insight into the importance of Se in oxidative stress.