Mechanisms Underlying the Metabolic Pathway of Selenium and the Interactions between Selenium and Other Elements

基于形态形成技术，研究了微量营养素硒在体内代谢转化的机理。方法：1.给大鼠灌胃富集稳定同位素标记的硒化合物，采用高效液相-电感耦合等离子体质谱多元素同时检测的方法对标记的硒的化学形态进行测定。有机和无机形式的硒都可以作为硒的营养来源。采用高效液相色谱-电感耦合等离子体质谱(HPLCICMS)法对大鼠静脉或口服富硒后的无机形态硒、亚硒酸盐和亚硒酸盐进行了测定。尿硒主要代谢产物为适量(0.2μg/g日粮)和过量硒(2.0μg/g日粮)。通过质谱学和~1H-核磁共振数据推测其化学结构为一种新的含硒糖。新陈代谢的…使用一种具有代表性的硒氨基酸--硒蛋氨酸，研究了有机形式硒的更多途径。用化学方法合成了富硒蛋氨酸，并将其应用于大鼠。硒蛋氨酸的硒以与无机亚硒酸盐相同的亚硒糖的形式排入尿液中，这表明即使在过量喂养的情况下，硒蛋氨酸的硒也会被识别为硒而代谢。通过饲喂适量和过量的富硒蛋氨酸，比较了无机亚硒酸盐和有机亚硒蛋氨酸对硒的利用效率。在饲养30天后，测定了大部分器官和体液中富硒与天然硒的相对比例。指出了两种营养硒化学物质在器官间和两种营养物质之间交换率的特点。硒与其他元素的生物相互作用以前主要集中在汞、硒与血浆蛋白硒蛋白P之间形成三元络合物，现在则集中在砷上。根据大鼠给药后砷的形态数据，特别是通过表征胆汁中砷的化学形态，即甲基化和还原反应的代谢物以及与谷胱甘肽的结合，揭示了砷在肝脏中的精确代谢途径。较少

Mechanisms underlying the metabolic transformation of the micronutrient selenium in the body have been studied based on the speciation technique.1. Selenium chemicals labeled with an enriched stable isotope were administered to rats, and the chemical forms of the labeled selenium were determined by the HPLC-ICP MS method with simultaneous detection of multi-elements.2. Both organic and inorganic forms of selenium can be utilized as the nutritional source for selenium. Inorganic forms of selenium, selenite and selenate labeled with an enriched selenium were administered intravenously or orally to rats, and the chemical forms of labeled selenium in the bloodstream, liver and urine were determined by the HPLC-ICP MS method. The major urinary selenium metabolite was obtained by feeding adequate (0.2 μg/g diet) and excessive selenium (2.0 μg/g diet). The chemical structure was deduced to be a new selenium-containing sugar (selenosugar) by mass spectrometric and ^1H-NMR data.3. The metabolic … More pathways for organic forms of selenium were studied using a representative selenoamino acid, selenomethionine. ^<82>Se-Enriched selenomethionine was synthesized chemically, and it was administered to rats. Selenium of selenomethionine was excreted into the urine in the form of the same selenosugar as that of inorganic selenite, suggesting selenium of selenomethionine is metabolized with recognition of selenomethionine as selenium even by feeding it at an excessive dose.4. Efficiency for the utilization of selenium was compared between inorganic selenite and organic selenomethionine by feeding enriched ones at adequate and excessive doses. The relative ratios between enriched and naturally occurring selenium were determined for most of organs and body fluids with time after feeding them for 30 days. Characteristics in the exchange ratios were pointed out among organs and between the two nutritional selenium chemicals.5. Biological interactions of selenium with other elements were focused on the formation of ternary complex between mercury, selenium and the plasma protein selenoprotein P previuously and now on arsenic. Precise metabolic pathway for arsenic in the liver was revealed based on the speciation data after administering arsenite to rats, especially by characterizing chemical forms of arsenic in the bile, namely metabolites by methylation and reduction reactions, and conjugation with glutathione. Less