ABSTRACT
A review of studies on radioprotection by selenium (Se) compounds indicates that various inorganic and organic selenium compounds, when administered at pharmacologic doses, provide a small degree of protection, as measured by increased survival of irradiated rodents. A dose reduction factor (DRF = treatment LD50/30 divided by control LD50/30) no greater than 1.2 can be achieved by administration of selenium compounds. Both the inorganic salt sodium selenite and the organic Se compound selenomethionine enhance the survival of β-irradiated mice (60Co, 20 cGy/min) when injected IP either before (–24 hr or –1 hr) or shortly after (+15 min) radiation exposure. An advantage of selenomethionine is lower lethal and behavioral toxicity (locomotor activity decrement) compared to sodium selenite, when they are administered at equivalent doses of Se. Pretreatment or simultaneous treatment with sodium selenite improves the radioprotective efficacy of WR-2721 (S-2-(3-aminopropylamino)-ethylphosphorothioic acid), one of the most effective radioprotective agents. The lethal toxicity, but not the behavioral toxicity, of WR2721 is reduced by pretreatment with sodium selenite. Pretreatment with sodium selenite also contributes to the increased survival and accelerated hematopoietic regeneration observed in irradiated mice that are treated with WR-2721 in combination with the immunomodulator glucan. The radioprotective effects of selenium compounds, administered alone or in combination with other agents, may be related to their ability to serve as precursors of glutathione peroxidase and other endogenous selenium-containing compounds, or as unmetabolized compounds to detoxify peroxides directly.
