Investigation of the protective effects of different forms of selenium in freezing dog semen: Comparison of nanoparticle selenium and sodium selenite.

This study aimed to investigate the protective effects of nanoparticle selenium (SeNP) and sodium selenite (SS) on preventing oxidative stress during the freezing process of dog semen. A total of six dogs were used in the study. The ejaculate was collected from dogs three times at different times by massage method. A total of 18 ejaculates were used and each ejaculate was divided in five experimental groups. The experimental groups were designed to tris extender containing no antioxidants control, 1 µg/mL SeNP1, 2 µg/mL SeNP2, and 1 µg/mL SS1 and 2 µg/mL SS2. Extended semen were equilibrated for 1 h at 4°C, then frozen in liquid nitrogen vapour and stored in liquid nitrogen (~-196°C). After thawing, semen samples were evaluated in terms of CASA motility and kinematic parameters, spermatozoa plasma membrane integrity and viability (HE Test), spermatozoa morphology (SpermBlue) and DNA fragmentation (GoldCyto). Antioxidant enzyme activity (glutathione peroxidase; GPX, superoxide dismutase; SOD, catalase; CAT) and lipid peroxidation (malondialdehyde; MDA) were evaluated in frozen-thawed dog sperm. When the results were evaluated statistically, the progressive motility, VCL, and VAP kinematic parameters in the SeNP1 group were significantly higher than the control group after thawing (p < .05). The highest ratio of plasma membrane integrity and viable spermatozoa was observed in the SeNP1 group, but there was no statistical difference found between the groups (p > .05). Although the ratio of total morphological abnormality was observed to be lower in all groups to which different selenium forms were added, compared to the control group, no statistical difference was found. Spermatozoa tail abnormality was significantly lower in the SeNP1 group than in the control and SS2 group (p < .05). The lowest ratio of fragmented DNA was observed in the SeNP1 group, but there was no statistical difference was found between the groups (p > .05). Although there was no statistical difference between the groups in the evaluation of sperm antioxidant profile, the highest GPX, SOD and CAT values and the lowest lipid peroxidation values were obtained in the SeNP1 group. As a result, it was determined that 1 µg/mL dose of SeNP added to the tris-based extender in dog semen was beneficial on spermatological parameters, especially sperm kinematic properties and sperm morphology, and therefore nanoparticle selenium, a nanotechnology product, made a significant contribution to the freezing of dog semen.

Effects of replacing Na selenite in laying hen feed with selenized glucose on production performance, egg quality, egg selenium content, microbial population, immunological response, antioxidant enzymes, and fatty acid composition.

This study aimed to explore the effects of selenized glucose (SeGlu) and Na selenite supplementation on various aspects of laying hens such as production performance, egg quality, egg Se concentration, microbial population, antioxidant enzymes activity, immunological response, and yolk fatty acid profile. Using a 2 × 2 factorial design, 168 laying hens at 27-wk of age were randomly divided into 4 treatment groups with 7 replications. Se source (Na selenite and SeGlu) and Se level (0.3 and 0.6 mg/kg) were used as treatments. When 0.3 mg SeGlu/kg was compared to 0.3 mg Na selenite/kg, the interaction findings revealed that 0.3 mg SeGlu/kg increased egg production percent and shell ash (P < 0.05). When compared to 0.3 mg Na selenite/kg, dietary supplementation with 0.3 and 0.6 mg SeGlu/kg resulted in an increase in albumen height, Haugh unit, and yolk color of fresh eggs (P < 0.05). SeGlu enhanced albumen height, Haugh unit, shell thickness (P < 0.01), albumen index, yolk share, specific gravity, shell ash (P < 0.05) of fresh eggs and shell thickness (P < 0.05) of stored eggs as compared to Na selenite. The interaction showed that 0.6 mg SeGlu/kg enhanced yolk Se concentration while decreasing malondialdehyde levels in fresh egg yolk (P < 0.05). SeGlu enhanced Se concentration in albumen and glutathione peroxidase activity in plasma (P < 0.05) as compared to Na selenite. 0.6 mg Se/kg increased lactic acid bacteria, antibody response to sheep red blood cells, and lowered ∑n-6 PUFA/ ∑n-3 PUFA ratio (P < 0.05). As a result, adding SeGlu to the feed of laying hens enhanced egg production, egg quality, egg Se concentration, fresh yolk lipid oxidation, and glutathione peroxidase enzyme activity.

Preclinical Evaluation of Sodium Selenite in Mice: Toxicological and Tumor Regression Studies after Striatum Implantation of Human Glioblastoma Stem Cells.

Glioblastoma (GBM) is the most aggressive malignant glioma, with a very poor prognosis; as such, efforts to explore new treatments and GBM's etiology are a priority. We previously described human GBM cells (R2J-GS) as exhibiting the properties of cancer stem cells (growing in serum-free medium and proliferating into nude mice when orthotopically grafted). Sodium selenite (SS)-an in vitro attractive agent for cancer therapy against GBM-was evaluated in R2J-GS cells. To go further, we launched a preclinical study: SS was given orally, in an escalation-dose study (2.25 to 10.125 mg/kg/day, 5 days on, 2 days off, and 5 days on), to evaluate (1) the absorption of selenium in plasma and organs (brain, kidney, liver, and lung) and (2) the SS toxicity. A 6.75 mg/kg SS dose was chosen to perform a tumor regression assay, followed by MRI, in R2J-GS cells orthotopically implanted in nude mice, as this dose was nontoxic and increased brain selenium concentration. A group receiving TMZ (5 mg/kg) was led in parallel. Although not reaching statistical significance, the group of mice treated with SS showed a slower tumor growth vs. the control group (p = 0.08). No difference was observed between the TMZ and control groups. We provide new insights of the mechanisms of SS and its possible use in chemotherapy.

Selenium and the 15kDa Selenoprotein Impact Colorectal Tumorigenesis by Modulating Intestinal Barrier Integrity.

Selenoproteins play important roles in many cellular functions and biochemical pathways in mammals. Our previous study showed that the deficiency of the 15 kDa selenoprotein (Selenof) significantly reduced the formation of aberrant crypt foci (ACF) in a mouse model of azoxymethane (AOM)-induced colon carcinogenesis. The objective of this study was to examine the effects of Selenof on inflammatory tumorigenesis, and whether dietary selenium modified these effects. For 20 weeks post-weaning, Selenof-knockout (KO) mice and littermate controls were fed diets that were either deficient, adequate or high in sodium selenite. Colon tumors were induced with AOM and dextran sulfate sodium. Surprisingly, KO mice had drastically fewer ACF but developed a similar number of tumors as their littermate controls. Expression of genes important in inflammatory colorectal cancer and those relevant to epithelial barrier function was assessed, in addition to structural differences via tissue histology. Our findings point to Selenof's potential role in intestinal barrier integrity and structural changes in glandular and mucin-producing goblet cells in the mucosa and submucosa, which may determine the type of tumor developing.

Effects of Sodium Selenite Injection on Serum Metabolic Profiles in Women Diagnosed with Breast Cancer-Related Lymphedema-Secondary Analysis of a Randomized Placebo-Controlled Trial Using Global Metabolomics.

In our previous study, intravenous (IV) injection of selenium alleviated breast cancer-related lymphedema (BCRL). This secondary analysis aimed to explore the metabolic effects of selenium on patients with BCRL. Serum samples of the selenium-treated (SE, n = 15) or the placebo-controlled (CTRL, n = 14) groups were analyzed by ultra-high-performance liquid chromatography with Q-Exactive Orbitrap tandem mass spectrometry (UHPLC-Q-Exactive Orbitrap/MS). The SE group showed a lower ratio of extracellular water to segmental water (ECW/SW) in the affected arm to ECW/SW in the unaffected arm (arm ECW/SW ratio) than the CTRL group. Metabolomics analysis showed a valid classification at 2-weeks and 107 differential metabolites were identified. Among them, the levels of corticosterone, LTB4-DMA, and PGE3-which are known anti-inflammatory compounds-were elevated in the SE group. Pathway analysis demonstrated that lipid metabolism (glycerophospholipid metabolism, steroid hormone biosynthesis, or arachidonic acid metabolism), nucleotide metabolism (pyrimidine or purine metabolism), and vitamin metabolism (pantothenate and CoA biosynthesis, vitamin B6 metabolism, ascorbate and aldarate metabolism) were altered in the SE group compared to the CTRL group. In addition, xanthurenic acid levels were negatively associated with whole blood selenium level (WBSe) and positively associated with the arm ECW/SW. In conclusion, selenium IV injection improved the arm ECW/SW ratio and altered the serum metabolic profiles in patients with BCRL, and improved the anti-inflammatory process in lipid, nucleotide and vitamin pathways, which might alleviate the symptoms of BCRL.

Increasing selenium supply during the close-up dry period improves nutrient metabolism and attenuates inflammatory response after calving in dairy cows.

The objective of this study was to investigate whether feeding selenium (Se)-replete cows a Se-yeast supplement in late pregnancy affects nutrient metabolism and inflammatory response during the periparturient period. Twenty cows were randomly assigned to two groups with 10 cows each. Cows in one group received Se-yeast at 0.3 mg Se/kg DM during the last 4 weeks before calving in addition to fed a TMR containing supplemented sodium selenite at 0.3 mg Se/kg DM (Se-yeast), while cows in another group were only fed a TMR containing supplemented sodium selenite at 0.3 mg Se/kg DM (Control). Blood samples were collected and analyzed for nonesterified fatty acids (NEFA), ß-hydroxybutyrate (BHBA), glucose, insulin, tumor necrosis factor-α (TNF-α), interleukin (IL)-1ß, IL-6, serum amyloid A (SAA), haptoglobin (Hp), and albumin. In control cows, plasma NEFA, IL-1ß, IL-6, SAA, and Hp levels increased after calving, but glucose, insulin, and albumin levels decreased after parturition. Se-yeast supplemental cows had lower postpartum concentrations of NEFA, TNF-α, IL-1ß, IL-6, SAA, and Hp, and higher postpartum levels of glucose, insulin, and albumin compared with control cows. The results indicate that feeding Se-replete cows a Se-yeast supplement in late pregnancy improves nutrient metabolism and attenuates the inflammatory response after calving.

Selenium nanoparticles inhibit the formation of atherosclerosis in apolipoprotein E deficient mice by alleviating hyperlipidemia and oxidative stress.

Atherosclerosis can cause severe cardiovascular diseases, which is the most common cause of death in the world. It's of great significance to study the prevention and treatment of atherosclerosis. Selenium nanoparticles (SeNPs) has drawn more and more attention due to high biological activity, high bioavailability, strong antioxidant capacity and low toxicity, exhibiting great potential in biomedical application. Thus, this study aimed at explore the anti-atherosclerotic effect of two kinds of SeNPs, bovine serum albumin (BSA) surface-decorated SeNPs and chitosan (CS) surface-decorated SeNPs (CS-SeNPs), in apolipoprotein E deficient (ApoE-/-) mice fed with a high-cholesterol and high-fat diet, and the possible mechanisms. The results demonstrated that both BSA-SeNPs (25, 50 and 100 µg Se/kg body weight/day) and CS-SeNPs (50 µg Se/kg body weight/day) could reduce atherosclerotic lesions in ApoE-/- mice after oral administration for 12 weeks. And these effects might mainly attributed to the ability of BSA-SeNPs and CS-SeNPs to inhibit hyperlipidemia by suppressing hepatic cholesterol and fatty acid metabolism, and alleviate oxidative stress by enhancing antioxidant activity. Moreover, the benefits of BSA-SeNPs were dose-dependent and the medium dose of BSA-SeNPs (50 µg Se/kg body weight/day) was optimal. Generally, BSA-SeNPs with mean size 38.5 nm and negative surface charge showed better anti-atherosclerotic effect than CS-SeNPs with mean size 65.8 nm and positive surface charge. These results suggested that SeNPs could significantly alleviate the formation of atherosclerosis in ApoE-/- mice, possibly by inhibiting hyperlipidemia and oxidative stress, exhibiting a potential to serve as an anti-atherosclerotic agent.

Selenium supplementation inhibits IGF-1 signaling and confers methionine restriction-like healthspan benefits to mice.

Methionine restriction (MR) dramatically extends the healthspan of several organisms. Methionine-restricted rodents have less age-related pathology and increased longevity as compared with controls, and recent studies suggest that humans might benefit similarly. Mechanistically, it is likely that the decreased IGF-1 signaling that results from MR underlies the benefits of this regimen. Thus, we hypothesized that interventions that decrease IGF-1 signaling would also produce MR-like healthspan benefits. Selenium supplementation inhibits IGF-1 signaling in rats and has been studied for its putative healthspan benefits. Indeed, we show that feeding mice a diet supplemented with sodium selenite results in an MR-like phenotype, marked by protection against diet-induced obesity, as well as altered plasma levels of IGF-1, FGF-21, adiponectin, and leptin. Selenomethionine supplementation results in a similar, albeit less robust response, and also extends budding yeast lifespan. Our results indicate that selenium supplementation is sufficient to produce MR-like healthspan benefits for yeast and mammals.

The mixed application of organic and inorganic selenium shows better effects on incubation and progeny parameters.

This experiment aims to study the effects of dietary selenium (Se) sources on the production performance, reproductive performance, and maternal effect of breeder laying hens. A total of 2,112 Hyline brown breeder laying hens of 42 wk of age were selected and randomly divided into 3 groups, with 8 repeats in each group and 88 chickens per repeat. The sources of dietary Se were sodium selenite (SS, added at 0.3 mg/kg), L-selenomethionine (L-SM, added at 0.2 mg/kg), and combination of SS and L-SM (SS 0.15 mg/kg + L-SM 0.15 mg/kg). The pretest period was 7 d, and the breeding period was 49 d. Compared with 0.3 mg/kg SS, the addition of 0.2 mg/kg L-SM in the diet significantly increased the hatchability (P < 0.05) and the Se content (P < 0.05) in egg yolk and chicken embryo tissues and improved the activity of yolk glutathione peroxidase (GSH-px) effectively (P < 0.05). Treatment with 0.2 mg/kg L-SM also reduced the content of yolk malondialdehyde (P < 0.05) and significantly improved the antioxidant performance of 1-day-old chicks, as manifested by increased activity of antioxidant enzymes (GSH-px, total antioxidant capacity and the ability to inhibit hydroxyl radicals) in serum, pectoral, heart, and liver (P < 0.05). This treatment decreased the malondialdehyde content (P < 0.05) and increased the expression of liver glutathione peroxidase 4 and deiodinase 1 mRNA (P < 0.05). Adding L-SM to the diets of chickens increased the hatchability of breeder eggs as well as the amount of Se deposited and antioxidant enzyme activity in breeder eggs and embryos. Compared with SS, L-SM was more effectively transferred from the mother to the embryo and offspring, showing efficient maternal nutrition. For breeder diets, the combination of organic and inorganic Se (0.15 mg/kg SS + 0.15 mg/kg L-SM) is an effective nutrient supplementation technology program for effectively improving the breeding performance of breeders and the antioxidant performance and health level of offspring chicks.

Efficacy and safety of an adsorbent and anti-oxidative vaginal gel on CIN1 and 2, on high-risk HPV, and on p16/Ki-67: a randomized controlled trial.

PURPOSE: The effect of SAM vaginal gel, a medical device containing adsorptive silicon dioxide and antioxidative sodium selenite and citric acid, on histologically-proven cervical intraepithelial neoplasia type 2 (CIN2) as well as p16 positive CIN1, and on the presence of the onco-marker p16 was investigated. METHODS: 216 women aged 25-60 years were randomized to either receive an intravaginal daily dose of SAM gel for three 28-day periods, or be followed-up without intervention. The primary endpoint was efficacy, defined as a combined histological and cytological regression. At baseline and after 3 months participants had: a guided biopsy including p16 immunohistochemical (IHC) staining, only if a lesion was visible at colposcopy; a cervical smear for cytology, high-risk human papillomavirus (hr-HPV) and a p16/Ki-67 test. At 6 months a further cytology and p16/Ki-67 test was performed. RESULTS: Regression of CIN lesions was observed in 78 out of 108 patients (72.2%) in the SAM gel arm and in 27 out of 108 patients (25.0%) in the control arm. Similarly, the change in the p16/Ki-67 cytological test status was significantly in favor of the treatment arm. The prevalence of hr-HPV decreased significantly (p < 0.001) in the treatment arm, from 87.0% to 39.8%, while it slightly increased in the control arm, from 78.7% to 83.3%. At 6 months the cytological regression in the treatment group and the highly significant effect on p16/Ki-67 was still present. CONCLUSION: SAM vaginal gel enhances the regression of cervical lesions and clears hr-HPV and p16/Ki-67 in smears significantly, thus offering an active non-destructive management to prevent cervical cancer. TRIAL REGISTRATION NUMBER: ISRCTN11009040, date of registration: 10/12/2019; https://doi.org/10.1186/ISRCTN11009040 ; retrospectively registered.

Antidiabetic effects of selenium-enriched Bifidobacterium longum DD98 in type 2 diabetes model of mice.

Both selenium and probiotics have shown antidiabetic effects in a type 2 diabetes model. The objective of this study is to investigate the alleviating effects of selenium-enriched Bifidobacterium longum DD98 (Se-B. longum DD98) on diabetes in mice and explore the possible underlying mechanism. A type 2 diabetes model was established using a high-fat diet and streptozotocin (STZ) injection in mice. To investigate the beneficial effects of Se-B. longum DD98, diabetic mice were then treated with B. longum DD98, Se-B. longum DD98, or sodium selenite (Na2SeO3) for three weeks. The results suggested that all three treatments could reduce the levels of fasting blood glucose (FBG), glycated hemoglobin (HbA1c), insulin and leptin, improve glucose tolerance, regulate lipid metabolism, and protect against the impairment of the liver and pancreas, while Se-B. longum DD98 showed a greater effect on relieving the above mentioned symptoms of type 2 diabetes in mice. Furthermore, this effect was associated with butyrate production and inflammatory response. Se-B. longum DD98 better increased the level of butyrate in feces and decreased the levels of proinflammatory cytokines in the pancreas compared with B. longum DD98 and Na2SeO3, leading to ameliorative insulin resistance. Se-B. longum DD98 also improved the glucagon like peptide-1 (GLP-1) level in serum and intestinal cells, which protected the pancreatic ß-islet cells from damage induced by type 2 diabetes. These results demonstrated that Na2SeO3, B. longum DD98, or Se-B. longum DD98 could alleviate the progression of type 2 diabetes in mice. Se-B. longum DD98 showed greater antidiabetic effects than the other two treatments, and could be considered as a promising candidate for treating type 2 diabetes.

The Role of Selenium Mineral Trace Element in Exercise: Antioxidant Defense System, Muscle Performance, Hormone Response, and Athletic Performance. A Systematic Review.

Exercise overproduces oxygen reactive species (ROS) and eventually exceeds the body's antioxidant capacity to neutralize them. The ROS produce damaging effects on the cell membrane and contribute to skeletal muscle damage. Selenium (Se), a natural mineral trace element, is an essential component of selenoproteins that plays an important role in antioxidant defense. The activity of the enzyme glutathione peroxidase (GPx), a highly-efficient antioxidant enzyme, is closely dependent on the presence of Se. These properties of Se may be potentially applicable to improve athletic performance and training recovery. We systematically searched for published studies to evaluate the effectiveness of Se supplementation on antioxidant defense system, muscle performance, hormone response, and athletic performance among physically active individuals. We used the Preferred Reporting Elements for Systematic Reviews and Meta-Analysis (PRISMA) guidelines and searched in SCOPUS, Web of Science (WOS), and PubMed databases to identify published studies until March 2020. The systematic review incorporated original studies with randomized controlled crossover or parallel design in which intake of Se administered once a day was compared with the same placebo conditions. No exclusions were applied for the type of physical exercise performed, the sex, nor the age of the participants. Among 150 articles identified in the search, 6 met the criteria and were included in the systematic review. The methodological quality of the studies was evaluated using the McMaster Critical Review Form. Oral Se supplementation with 180 µg/day or 240 µg/day (selenomethionine) and 200 µg/day (Sodium Selenite), significantly decreased lipid hydroperoxide levels and increased GPx in plasma, erythrocyte, and muscle. No significant effects were observed on athletic performance, testosterone hormone levels, creatine kinase activity, and exercise training-induced adaptations on oxidative enzyme activities or on muscle fiber type myosin heavy chain expression. In addition, Se supplementation showed to have a dampening effect on the mitochondria changes in chronic and acute exercise. In summary, the use of Se supplementation has no benefits on aerobic or anaerobic athletic performance but it may prevent Se deficiencies among athletes with high-intensity and high-volume training. Optimal Se plasma levels may be important to minimize chronic exercise-induced oxidative effects and modulate the exercise effect on mitochondrial changes.

Copper sulfate and sodium selenite lipid-microencapsulation modifies ruminal microbial fermentation in a dual-flow continuous-culture system.

Undesirable interactions between trace mineral elements and ruminal contents may occur during digestion when mineral salts are supplemented. Antimicrobial effects of copper sulfate (CuSO4) may affect ruminal digestibility of nutrients when fed as a source of copper (Cu), while sodium selenite (Na2SeO3) may be reduced in the rumen to less available forms of selenium (Se). Our objective was to evaluate if protection of CuSO4 and Na2SeO3 by lipid-microencapsulation would induce changes on ruminal microbial fermentation. We used 8 fermentors in a dual-flow continuous-culture system in a 4 × 4 duplicated Latin square with a 2 × 2 factorial arrangement of treatments. Factors were CuSO4 protection (unprotected and protected by lipid-microencapsulation) and Na2SeO3 protection (unprotected and protected by lipid-microencapsulation). Treatments consisted of supplementation with 15 mg/kg of Cu and 0.3 mg/kg of Se from either unprotected or protected (lipid-microencapsulated) sources, as follows: (1) Control (unprotected CuSO4 + unprotected Na2SeO3); (2) Cu-P (protected CuSO4 + unprotected Na2SeO3); (3) Se-P (unprotected CuSO4 + protected Na2SeO3); (4) (Cu+Se)-P (protected CuSO4 + protected Na2SeO3). All diets had the same nutrient composition and fermentors were fed 106 g of dry matter/d. Each experimental period was 10 d (7 d of adaptation and 3 d for sample collections). Daily pooled samples of effluents were analyzed for pH, NH3-N, nutrient digestibility, and flows (g/d) of total N, NH3-N, nonammonia N (NAN), bacterial N, dietary N, and bacterial efficiency. Kinetics of volatile fatty acids was analyzed in samples collected daily at 0, 1, 2, 4, 6, and 8 h after feeding. Main effects of Cu protection, Se protection, and their interaction were tested for all response variables. Kinetics data were analyzed as repeated measures. Protection of Cu decreased acetate molar proportion, increased butyrate proportion, and tended to decrease acetate:propionate ratio in samples of kinetics, but did not modify nutrient digestibility. Protection of Se tended to decrease NH3-N concentration, NH3-N flow, and CP digestibility; and to increase flows of nonammonia N and dietary N. Our results indicate that protection of CuSO4 may increase butyrate concentration at expenses of acetate, while protection of Na2SeO3 tended to reduce ruminal degradation of N. Further research is needed to determine the effects of lipid-microencapsulation on intestinal absorption, tissue distribution of Cu and Se, and animal performance.

Supplementation of insulin-transferrin-sodium selenite in culture medium improves the hypothermic storage of bovine embryos produced in vitro.

Hypothermic storage of gametes and embryos at 4 °C can be used as an alternative to cryopreservation, but hypothermic preservation can maintain embryo viability for a short duration only. This study investigated the effect of insulin-transferrin-sodium selenite (ITS) in embryo culture medium on hypothermic storage of bovine embryos at 4 °C. Day 7 bovine embryos were subjected to hypothermic storage in tissue culture medium 199 supplemented with 50% fetal bovine serum and 25 mM HEPES for different time durations. After recovery, the embryos were assessed for survival and hatching rate and gene and protein expression levels. Supplementation of embryo culture medium with ITS significantly increased (P < 0.05) the survival and hatching ability of blastocysts stored at 4 °C for 72 h compared to the control group (100% and 76.3% vs 68.5% and 40.5%, respectively). Furthermore, the beneficial effects of ITS on embryos were associated with greater (P < 0.05) total cell number per blastocyst and lesser apoptotic cells number. Moreover, embryos cultured in ITS had lower intracellular lipid content. The protein expression of sirt1 was greater (P < 0.05) in the ITS group, however, caspase3 protein expression was significantly lesser (P < 0.05) in the ITS group. Quantitative reverse transcription PCR indicated that the mRNA levels of SIRT1 and HSP70 were (P < 0.05) increased upon culture with ITS; however, the mRNA levels of the pro-apoptotic genes BAX and CASP3 were reduced (P < 0.05). Taken together, these data suggest that supplementation of embryo culture medium with ITS improves in vitro bovine embryo quality and survival following hypothermic storage.

Co-administration of Selenium with Inorganic Mercury Alters the Disposition of Mercuric Ions in Rats.

Mercury (Hg) is a common environmental toxicant to which humans are exposed regularly through occupational and dietary means. Although selenium supplementation has been reported to prevent the toxic effects of Hg in animals, the mechanisms for this prevention are not well understood. The purpose of the current study was to determine the effects of selenium on the disposition and toxicity of Hg. Wistar rats were injected intravenously with a non-nephrotoxic dose (0.5 µmol kg-1) or a nephrotoxic dose (2.5 µmol kg-1) of HgCl2 (containing radioactive Hg) with or without co-administration of sodium selenite (Na2SeO3). Twenty-four hours after exposure, rats were euthanized, and organs were harvested. Co-administration of SeO32- with HgCl2 reduced the renal burden of Hg and the urinary excretion of Hg while increasing the amount of Hg in blood and spleen. We propose that Hg reacts with reduced selenite in the blood to form large Hg-Se complexes that are unable to be filtered at the glomerulus. Consequently, these complexes remain in the blood and are able to accumulate in blood-rich organs. These complexes, which may have fewer toxic effects than other species of Hg, may be eliminated slowly over the course of weeks to months.

Performance, carcass characteristics and meat quality of Nellore cattle supplemented with supranutritional doses of sodium selenite or selenium-enriched yeast.

The enrichment of meat with selenium is important to improve the intake of selenium by humans. The effects of supranutritional doses of sodium selenite or selenium-enriched yeast on performance, carcass characteristics and meat quality were evaluated using 63 Nellore cattle in a completely randomized design with two sources (sodium selenite and selenium-enriched yeast), three levels (0.3, 0.9 and 2.7 mg Se/kg DM) and control treatment (without addition of selenium). Final body weight (BW), average daily gain, dry matter intake and gain to feed ratio (G : F) at the end of 84 days of supplementation were not influenced by treatments (P>0.05). Values of pH, ribeye area, back fat thickness and marbling score were also not influenced by treatments ( P>0.05). Dressing percentage was greater (P=0.02) in Nellore cattle supplemented with organic Se (58.70%) compared to animals supplemented with inorganic Se (57.94%). Hot carcass weight increased ( P=0.05) with the increasing of Se levels in the diet. Colour, shear force (SF), cooking and drip loss remained unchanged ( P>0.05); however thiobarbituric acid reactive substances was 15.51% higher with inorganic Se compared with organic Se. The selenium concentration in the meat of animals receiving organic selenium was higher ( P<0.001) than that of animals receiving sodium selenite, at all levels (0.3; 0.9 and 2.7 mg/kg DM). The meat of animals receiving 2.7 mg of organic Se/kg of DM presented concentration of 372.7 µg Se/kg in the L.dorsi muscle, and the intake of 150 g of this meat by humans provides approximately 100% of the recommended Se intake (55 µg Se/day for adults). Therefore, the use of supranutritional doses of 2.7 mg Se/kg of DM, regardless of source, is a way of naturally producing selenium-enriched meat without compromising performance, carcass characteristics and quality of Nellore bovine meat.

The Effect of Selenium on CYP450 Isoform Activity and Expression in Pigs.

Selenium is an essential nutrient in diets; however, the effects of selenium on enzyme metabolic activation are not currently clear. Cytochromes P450 (CYP450) are major phase I metabolic enzymes involved in the biotransformation of xenobiotics and endogenous compounds to form electrophilic reactive metabolites. To investigate the effect of selenium on CYP450 isoform activity, the Landrace pigs were divided into three groups: the control group (containing Se 0.15 mg/kg), the Se-deficient group (Se 0.03 mg/kg), and the Se-supply group (Se 0.35 mg/kg). After 1 week of administration, a mixed solution (20 mg/kg of dextromethorphan, phenacetin, chlorzoxazone, and 10 mg/kg of testosterone in a CMC-Na solution) was intravenously injected into all pigs. The mixed solution content and pharmacokinetic parameters were assayed by HPLC and DAS, respectively. To investigate the effect of selenium on CYP450 isoform expression, RNA-Seq analysis, Western boltting, and qPCR were used. Results showed that Se-supply group significantly increased the activity and expression of CYP1A2 and CYP2D25, and decreased CYP3A29. Se-deficient group decreased the activity of CYP1A2, CYP2D25, and CYP2E1. These results demonstrated that selenium content affecting the activity or expression of the CYP450 isoform may lead to a food-drug interaction.

Comparative study of yeast selenium vs. sodium selenite on growth performance, nutrient digestibility, anti-inflammatory and anti-oxidative activity in weaned piglets challenged by Salmonella typhimurium.

The present study was conducted to investigate the effects of dietary supplementation of selenium from different sources on the growth performance, nutrient digestibility, and blood immune indices of piglets orally challenged with Salmonella typhimurium (ST). In a 2 × 2 factorial arrangement, 32 piglets (6.43 ± 0.54 kg of body mass) were assigned into four groups with or without dietary inclusion of sodium selenite (SS) or yeast selenium (YS) and with or without ST challenge (5 ml 1 × 109 cfu/ml ST or 5 ml saline) on d 13. In each period, YS increased average daily feed intake and average daily gain but did not reach statistical significance. During the challenged stage, piglets fed YS had higher digestibility of dry matter, crude protein, crude fat, and YS reduced the amount of Escherichia coli in feces. Additionally, YS regulated the composition of T-lymphocyte subset and influenced the production of inflammatory cytokines. In conclusion, in this study selenium-enriched yeast was more effective in enhancing nutrient digestibility, and inhibiting inflammation and oxidative stress by inducing the activity of the lymphocytes, expression of antioxidant enzymes and so on.

Pharmacokinetics of Sodium Selenite in Rat Plasma and Tissues After Intragastric Administration.

The purpose of this research is to investigate the absorption, distribution, excretion, and pharmacokinetics of selenite in rats after intragastric administration, and thus illustrate the efficiency of selenium (Se) supplementation. After a single gavage of sodium selenite, a concentration of Se in plasma and tissues was determined by inductively coupled plasma mass spectrometry (ICP-MS) at different time points. Through fitting the data with the metabolic kinetic model, the corresponding kinetic parameters were determined for plasma and tissues, including kidney, liver, heart, muscle, and gonad. While the metabolic kinetics of sodium selenite in plasma, liver, and kidney of rats was well reflected by a two-compartment open model, that in heart and gonad was fitted to a one-compartment open model, and that in muscle was fitted to a one-compartment open model with a lag time. The results indicate that sodium selenite was absorbed by plasma and tissues quickly and was eliminated slowly after intragastric administration. Based on the results, we propose that multi-supplementation of Se with low dosage is superior to single supplementation with high dosage, in terms of avoiding selenosis.

Early morphological changes in cardiac mitochondria after subcutaneous administration of trastuzumab in rabbits: possible prevention with oral selenium supplementation.

Trastuzumab-mediated cardiotoxicity poses a significant challenge in the treatment of human epidermal growth factor receptor 2-positive breast cancer. To understand the underlying mechanisms, we conducted experiments to determine ultrastructural changes of rabbit cardiac tissue under different experimental conditions, including differing doses of trastuzumab and supplementation with oral sodium selenite, an antioxidant. Histopathology revealed lymphocyte and macrophage infiltration in myocardium of rabbits receiving four doses of trastuzumab. Transmission electron microscopy showed substantial changes with trastuzumab, including edema with separation of myofibril bundles and rupture of sarcomeres. Within mitochondria, edema resulted in disorganization of the cristae. Some mitochondria exhibited eccentric projections of their membranes with disruption of both inner and outer membranes. These changes were seen to a lesser extent in rabbits who received oral sodium selenite prior to trastuzumab. Selenium is integral to functioning of mitochondrial glutathione peroxidases, important antioxidants that also maintain membrane integrity. If mitochondria are disrupted as part of trastuzumab cardiac toxicity, selenium supplementation might be an important therapeutic or preventive consideration. Larger studies to explore this hypothesis are warranted.