Effect of the chemical form of supranutritional selenium on selenium load and selenoprotein activities in virgin, pregnant, and lactating rats

Effects of Selenium-Enriched Protein from Ganoderma lucidum on the Levels of IL-1 β and TNF- α , Oxidative Stress, and NF- κ B Activation in Ovalbumin-Induced Asthmatic Mice

The purpose of this study was to compare the effect and toxicity of organic selenium (Pro-Se) with inorganic selenium (IOSe) in preventing asthma in ovalbumin-induced asthmatic mice. After the mice were treated orally with Pro-Se and IOSe, respectively, the plasma Se levels, Se accumulation in liver and kidney, tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β), oxidative stress, and NF-κB activation in lung were examined. The results showed that the serumal Se levels in the mice fed the Pro-Se were significant (P < 0.01) elevations. It results in restoration of the level of endogenous antioxidant enzyme, lower levels of TNF-α and IL-1β, and activated NF-κB in the asthmatic mice. Our experiments have demonstrated profound differences between the activities of organic selenium and inorganic selenium in experimental conditions. These data provide an important proof of the concept that organic selenium might be a new potential therapy for the management of childhood asthma in humans.

Evaluating the antioxidative activity of diselenide containing compounds in human blood

This study was designed to determine and compare the antioxidant effects of synthetic organoselenium compounds. In experimental trials three different diselenides were used: bis(2-hydroxyphenyl) diselenide, bis{[2-(4-hydroxybenzyl)imino]phenyl} diselenide and bis[2-(4-methylphenylsulfonylamino)phenyl] diselenide. The compounds were screened for antioxidant activities in human blood under oxidation stress conditions. Oxidative stress was induced in vitro in human blood platelet samples and in plasma by 0.1 mM peroxynitrite (ONOO(-)) or by Fe(2+). In experimental trials the levels of chosen oxidative stress markers (TBARS, O2(-), and protein carbonyl groups) were significantly decreased by the action of the tested compounds. The antioxidative properties and the changes in proteins and lipids in the presence of new synthesized selenoorganic compounds were studied in vitro and compared with activity of ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one)--a classical antioxidant, well known as the most important glutathione peroxidase mimetic agent. Our results indicate that the tested diselenides have distinctly protective effects against oxidative alterations of biomolecules caused by ONOO(-) and Fe(2+) in blood platelets and in plasma. Therefore it seems that not only ebselen with a wide spectrum of therapeutic actions but also other organoselenium compounds can be considered in the future as active pharmacological agents.

Dietary organic selenium improves growth, survival and resistance to Vibrio mimicus in cultured marron, Cherax cainii (Austin, 2002)

To determine the effects of dietary organic selenium (OS) supplementation on the growth performance and immune competence of marron, Cherax cainii (Austin, 2002), a group of marron were fed 0.2 g kg(-1) of Sel-Plex(®) supplemented basal diet and then compared with another group (control) of marron fed basal diet without any supplementation. After 90 days of feeding, final weight, average weekly gains (AWG), relative gain rate (RGR), specific growth rate (SGR), survival, total and differential haemocyte counts (THC and DHC), were compared between the two groups. Surviving marron from each group were then divided into three sub-groups (three tanks per sub-group with seven marron per tank); (1) first sub-group was injected with 20 μL of 3.24 × 10(6) cfu Vibrio mimicus; (2) the second sub-group was injected with 20 μL normal saline and (3) the third sub-group was not subjected to injection and became the control group. THC, DHC, neutral red retention time (NRRT) and Vibrio ranks of post-injected marron were evaluated for 96 h, at every 24-h interval. The results showed that after 90 days of feeding, final weight, AWG, RGR, SGR, survival, THC, proportion of hyaline cells of OS-fed marron were significantly higher (P < 0.05) than the control group, whereas proportion of granular and semigranular cells were not affected by dietary OS. After challenging with V. mimicus, survival rate of marron without dietary OS significantly decreased (P < 0.05) as compared to the control group of marron. THC of marron in all sub-groups were significantly reduced (P < 0.05) after the challenge. However, THC and granular cells of sub-groups fed OS were higher than other sub-groups. Vibrio ranks and NRRT of marron fed OS were significantly lower and slower, respectively, than marron fed without OS. These findings demonstrated the benefits of OS inclusion in the marron diet in terms of growth, health and disease resistance.

The Use of Selenium Enriched Enterococcus faecium as an Alternative Selenium Source for Growing-finishing Pigs

The aim of the study was to evaluate the effect of the feeding of selenium enriched Enterococcus faecium on selenium concentrations in muscle tissue and on meat quality indicators in finishing pigs. Groups of pigs fed Se-enriched E. faecium (n = 12), sodium selenite (n = 12) and Se-enriched yeast (n = 12) were used in the study. The tested feed mixtures were fed for a period of 3 months before the pigs were slaughtered. The selenium concentrations in muscle tissue achieved by the use of Se-enriched E. faecium were comparable to those achieved in sodium selenite diets and lower (p ≤ 0.05) compared to Se-enriched yeast. Concentration of Se in serum and glutathione peroxidase (GSH-Px) activities did not differ in animals fed different Se forms. No differences in indices of meat quality were found among the groups. Se-enriched E. faecium bacteria can be recommended as an alternative selenium source for finisher pigs with the similar efficacy as sodium selenite.

Effects of chemical species of selenium on maternal transfer during pregnancy and lactation

AIMS

This study compares the transfer from mother to fetuses and pups of selenium (Se) in the form of selenite, selenate, and selenomethionine (SeMet) labeled with different homo-elemental isotopes.

MAIN METHODS

To completely substitute endogenous Se with natural abundance with Se enriched with a single stable isotope (82Se), female Wistar rats delivered by mother fed 82Se-selenite were fed Se-deficient diet and drinking water containing 82Se-selenite immediately after weaning, and then mated with male Wistar rat at the age of 15-17 weeks. The pregnant rats were divided into two groups. One group was fed Se-deficient diet and drinking water containing 76Se-selenite, 78Se-selenate, and 77Se-SeMet from gestation days 11 to 20. The other group was fed the same diet and drinking water containing the three Se species after delivery for 10 days of lactation. Non-pregnant rats were also fed Se mixture and Se-deficient diet for 10 days.

KEY FINDING

Tissue and plasma Se concentrations showed significant changes among non-pregnant, pregnant, and lactating rats. The peak corresponding to selenoprotein P (Sel P) in serum of pregnant rats was reduced. The concentration of 77Se originating from SeMet was higher than those of 76Se from selenite and 78Se from selenate in the stomach content of pups.

SIGNIFICANCE

Inorganic Se species are more preferably transformed into Sel P than SeMet, and Sel P is effectively incorporated into placenta during pregnancy. On the other hand, SeMet is a more efficient Se source than inorganic Se species during lactation.

Effects of selenium status and supplementary seleno-chemical sources on mouse T-cell mitogenesis

Although selenium is thought to be essential for various immune responses, the excess supplementation may have an adverse effect on certain immunological functions. The present study was designed to determine the effective chemical forms of selenium and their optimal levels on T-cell mitogenesis with splenic cells from mice given a selenium-deficient diet for 8 weeks to avoid effects of cellular selenium sources. Although selenium in tissues, except for spleen and thymus, was almost depleted by feeding selenium-deficient diet, the lymphoid organs still contained low levels of selenium. Both activities of cellular glutathione peroxidase (cGPx) and thioredoxin reductase (TR) in liver and splenic cells showed a tendency to decrease by selenium deficiency. However, splenic cells were tolerant against decrease of the selenoenzyme activities, and TR was also more tolerant than cGPx. T-cell proliferation of the selenium-insufficient splenic cells induced by concanavalin A was increased by addition of Na2SeO3, Na2SeO4, Na2Se, seleno-DL-cystine, seleno-L-methionine and selenocystamine. Their promoting action was observed at levels lower than 0.1 micromol/L and was completely suppressed at the highest concentration (1 micromol/L), except for selenocystamine. Na2SeO3 was one of the efficient selenocompounds for the mitogenesis, which was concomitant with the significant induction of cGPx and TR. However, recovery of cGPx activity in the selenium-insufficient cells by supplementary Na2SeO3 was only partial,while TR activity was readily recovered from selenium deficiency. These results therefore indicate that only low levels of selenium is essential for T-cell mitogenesis even in selenium-insufficient splenic cells, and TR, which is readily recovered by Na2SeO3, may be the critical enzyme.

Efficacy of dietary selenium sources on growth and carcass characteristics of growing-finishing pigs fed diets containing high endogenous selenium

A study was conducted to determine the efficacy of organic (Se-yeast, SelenoSource AF, Diamond V Mills Inc., Cedar Rapids, IA) and inorganic sources of Se on growth performance, tissue Se accretion, and carcass characteristics of growing-finishing pigs fed diets with high endogenous Se content. A total of 180 pigs at 34.4 +/- 0.06 kg of BW were allotted to 1 of 5 dietary treatments: a negative control without added Se (NC); 3 treatment diets with 0.1, 0.2, or 0.3 mg/kg of added Se from an organic source; and a diet with 0.3 mg/kg of added Se as sodium selenite. Each treatment had 6 pens, with 6 pigs per pen-replicate. Experimental diets were changed twice at 66.1 +/- 0.5 kg and 99.0 +/- 0.9 kg of BW, and were fed until the pigs reached market weight. Growth performance was measured at the end of each phase. Upon reaching 129.9 +/- 1.4 kg of BW, the pigs were transported to a local abattoir (Seaboard Foods, Guymon, OK), where carcass, loin, and liver samples were obtained. Hair and blood samples were obtained at the beginning and end of the study for Se analysis. Growth performance did not differ (P > 0.05) among treatments. Percent drip loss of the NC pigs was greater (2.41 vs. 1.75, P = 0.011) compared with pigs supplemented with Se. Pigs fed diets with added Se had greater Se concentrations in the liver (0.397 vs. 0.323 ppm, P = 0.015), loin (0.236 vs. 0.132 ppm, P < 0.001), serum (0.087 vs. 0.062 ppm, P = 0.047), and hair (0.377 vs. 0.247 ppm, P = 0.003) compared with the NC pigs. Percentage drip loss was linearly reduced [percent drip loss = 2.305 - (2.398 x Se), r2 = 0.29, P = 0.007] as dietary organic Se concentration increased. The Se concentration (ppm) in the liver [liver Se = 0.323 + (0.291 x Se), r2 = 0.33, P = 0.003], loin [loin Se = 0.122 + (0.511 x Se), r2 = 0.57, P < 0.001], serum [serum Se = 0.060 + (0.113 x Se), r2 = 0.33, P = 0.004] and hair [hair Se = 0.237 + (0.638 x Se), r2 = 0.56, P < 0.001] increased linearly as dietary organic Se concentration increased. Slope ratio analysis indicated that the relative bioavailability of organic Se for percent drip loss and loin and hair Se response was 306, 192, and 197% of that for inorganic Se, respectively. The results of the study show a potential advantage of organic Se supplementation in reducing drip loss even when the basal diet contains an endogenously high Se concentration of 0.181 ppm.

Selenium, the thyroid, and the endocrine system

Recent identification of new selenocysteine-containing proteins has revealed relationships between the two trace elements selenium (Se) and iodine and the hormone network. Several selenoproteins participate in the protection of thyrocytes from damage by H(2)O(2) produced for thyroid hormone biosynthesis. Iodothyronine deiodinases are selenoproteins contributing to systemic or local thyroid hormone homeostasis. The Se content in endocrine tissues (thyroid, adrenals, pituitary, testes, ovary) is higher than in many other organs. Nutritional Se depletion results in retention, whereas Se repletion is followed by a rapid accumulation of Se in endocrine tissues, reproductive organs, and the brain. Selenoproteins such as thioredoxin reductases constitute the link between the Se metabolism and the regulation of transcription by redox sensitive ligand-modulated nuclear hormone receptors. Hormones and growth factors regulate the expression of selenoproteins and, conversely, Se supply modulates hormone actions. Selenoproteins are involved in bone metabolism as well as functions of the endocrine pancreas and adrenal glands. Furthermore, spermatogenesis depends on adequate Se supply, whereas Se excess may impair ovarian function. Comparative analysis of the genomes of several life forms reveals that higher mammals contain a limited number of identical genes encoding newly detected selenocysteine-containing proteins.

Time-dependent influence of supranutritional organically bound selenium on selenium accumulation in growing wether lambs

Crossbred wethers (n = 36; BW = 36.0 kg; SD = 3.4) were used to assess the time-dependent influence of supranutritional organically bound Se on Se accumulation. Four wethers were slaughtered before the trial began (d 0). The remaining wethers were fed diets containing adequate (0.2 microg of Se/g of DM) or supranutritional Se (2.9 microg of Se/g of DM; in the form of high-Se wheat grain) for 14, 28, 42, or 56 d before slaughter (four wethers per Se treatment at each slaughter day). The DMI was set at 3.1% of BW and adjusted weekly based on a targeted ADG of 150 g. Daily Se intake by wethers fed the adequate and supra-nutritional Se diets ranged from 5.3 to 5.9, and 79.0 to 95.0 microg of Se/kg of BW, respectively, and did not differ (P = 0.84 to 0.99) between slaughter day groups within Se treatment. Neither Se treatment nor Se treatment x slaughter day interactions were significant for BW, G:F, or liver, kidneys, and spleen weights (P = 0.06 to 0.84). Within the supranutritional Se treatment, Se contents of most organs and tissues from wethers slaughtered on d 14, 28, 42, and 56 were nearly twice the concentrations (P < 0.01) of wethers slaughtered on d 0. When regressed against the number of days the wethers were fed supranutritional Se, Se concentrations increased (P < 0.001) cubically in kidneys and plasma, quadratically in duodenum, lung, liver, and spleen, and linearly in heart, muscle, and wool. For total Se in kidneys, liver, and spleen, the response was quadratic (P < 0.03). Excluding skeletal muscle, heart, and wool, Se in other organs and tissues reached apparent steady-state concentrations 14 to 28 d after commencement of supranutritional Se diets. Selenium concentrations in skeletal muscle accumulated in a linear manner (P < 0.001) throughout the 56-d feeding period. High-Se grains can be used strategically to deliver supranutritional Se and rapidly enhance Se depots in sheep, a task that does not seem attainable with Se salts. Furthermore, a 100-g portion of uncooked loin (LM) from the wethers fed supranutritional Se contained 196 to 250% of the recommended Se requirement for humans.