Bioavailability of selenium from selenotrisulfides in primary cultured neuronal cells

Abstract

Selenium plays vital roles as a defense against oxidative stress in the central nervous system. This essential micronutrient is transported to the brain in the form of selenoprotein P. Additionally, small molecular-mass selenium compounds are also suggested to participate in supplying selenium to the brain, although its definitive transport pathways to the brain still remain unclear. Selenotrisulfide (−S−Se−S−, STS) is a metabolic intermediate of selenium and can react with free cysteine (Cys) thiols in proteins through the thiol-exchange reaction (R−S−Se−S−R’ + R”−SH → R−S−Se−S−R” + R’−SH). These reactions of free Cys thiols in human hemoglobin (Hb) and serum albumin (HSA) with STS are involved in the selenium metabolic and/or transport pathway in red blood cells. In this study, rat dorsal root ganglion (DRG) neurons are supplemented with STS species including STSs bound to HSA and Hb to determine the selenium utilization efficiency from STS species. After incubation with STS species for 72 h, the cellular selenium concentration and activity of selenium-dependent glutathione peroxidase in DRG neurons increased as well as those incubated with selenious acid. Selenium from STS is thought to be absorbed and utilized for the selenoprotein synthesis in neurons.

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