Absorption, distribution, metabolism and excretion of selenium following oral administration of elemental selenium nanoparticles or selenite in rats

Abstract

A suspension of nanoparticles of BSA-stabilized red amorphous elemental selenium (Se) or an aqueous solution of sodium selenite was repeatedly administered by oral gavage for 28 days at 0.05 mg kg À1 bw per day (low dose) or at 0.5 mg kg À1 bw per day (high dose) as Se to female rats. Prior to administration, the size distribution of the Se nanoparticles was characterized by dynamic light scattering and transmission electron microscopy, which showed that the particles' mean diameter was 19 nm and ranged in size from 10 to 80 nm. Following administration of the high dose of Se nanoparticles or selenite the concentration of Se was determined by ICP-MS in the liver, kidney, urine, feces, stomach, lungs, and plasma at the mg g À1 level and in brain and muscle tissue at the sub-mg g À1 level. In order to test if any elemental Se was present in the liver, kidney or feces, an in situ derivatization selective to elemental Se was performed by treatment with sulfite, which resulted in formation of the selenosulfate anion. This Se species was selectively and quantitatively determined by anion exchange HPLC and ICP-MS detection. The results showed that elemental Se was present in the livers, kidneys and feces of animals exposed to low and high doses of elemental Se nanoparticles or to selenite, and was also detected in the same samples from control animals. The fraction of Se present as elemental Se in livers and kidneys from the high dose animals was significantly larger than the similar fraction in samples from the low dose animals or from the controls.This suggested that the natural metabolic pathways of Se were exhausted when given the high dose of elemental Se or selenite resulting in a non-metabolized pool of elemental Se. Both dosage forms of Se were bioavailable as demonstrated by the blood biomarker selenoprotein P, which was equally up-regulated in the high-dose animals for both dosage forms of Se. Finally, the excretion of Se in urine and its occurrence as Se-methylseleno-N-acetyl-galactosamine and the trimethylselenonium-ion demonstrated that both dosage forms were metabolized and excreted. The results of the study showed that both forms of Se were equally absorbed, distributed, metabolized and excreted, but the detailed mechanism of the fate of the administered elemental Se or selenite in the gastro-intestinal tract of rats remains unclear.

A Prospective Investigation of Graves' Disease and Selenium: Thyroid Hormones, Auto-Antibodies and Self-Rated Symptoms

“…The samples were centrifuged and stored as plasma at -70°C with EDTA and were analysed together. The SePP was determined by affinity HPLC with ICP-MS detection and isotope dilution quantification of Se using a method previously described in detail [19]. …”

Anti-hyperglycemic activity of selenium nanoparticles in streptozotocin-induced diabetic rats

“…A Philips CM100 transmission electron microscope (TEM) (FEI, Eindhoven, the Netherlands), operating at 80 kV accelerating voltage was then used to image the size and shape of the SeNPs. 13 animals Adult male albino rats of the Wistar strain weighing 110-140 g were obtained from the Holding Company for Biological Products and Vaccines (VACSERA, Cairo, Egypt). After acclimatizing for 7 days, the animals were divided into seven groups (with seven rats per group) and housed in wire-bottomed cages in a room kept at 25°C±1°C and under a 12 hour light/12 hour dark cycle.…”

“…A STZ-SeNPs group consisted of diabetic rats treated with SeNPs at 0.1 mg of SeNPs/kg administered orally. 13 A STZ-insulin (Ins) group consisted of diabetic rats treated with standard drug insulin (6 U/kg, subcutaneous [sc] administration). Finally, a STZ-SeNPs-Ins group consisted of diabetic rats treated with SeNPs and the standard drug insulin.…”

XAS studies of Se speciation in selenite-fed rats

“…Recently, Loeschner et al reported the presence of elemental selenium in the liver (17% of total Se) and kidneys (40% of total Se) of rats fed 0.5 mg Se as selenite per kg of body weight per day for 28 days. 36 The species was detected by anion exchange HPLC and ICP-MS after being reduced in situ with sodium sulfite to the selenosulfate anion. Elemental Se was also detectable in the liver and kidneys of rats fed control and low Se diets, although at much lower concentrations (<10% of total Se).…”