Comparison of short-term toxicity between Nano-Se and selenite in mice

We previously reported that, as compared with selenite, nano red elemental selenium (Nano-Se) had lower acute toxicity in mice and similar bioavailability in terms of up-regulating seleno-enzymes. The short-term toxicity of both selenite and Nano-Se in mice was further compared in this study. At an oral dose of 6 mg/kg bw per day administered for consecutive 12 days, selenite and Nano-Se completely and partially suppressed mice growth respectively. Abnormal liver function was more pronounced with selenite treatment than Nano-Se as indicated by the increase of both alanine aminotransferase and aspartate aminotransferase in serum. Selenite inhibited liver catalase and superoxide dismutase activities, whereas, Nano-Se did not affect these two antioxidant enzymes. Selenite increased the malondialdehyde content of liver, but Nano-Se decreased it. Both Se forms had similar effects on depletion of reduced glutathione and up-regulated glutathione peroxidase. Nano-Se was more potent than selenite in the induction of glutathione S-transferase. At oral doses of 2 or 4 mg/kg bw per day for consecutive 15 days, selenite was more active than Nano-Se in supressing growth, deleting reduced glutathione, and inhibiting superoxide dismutase activities. Taken together, these results indicate that over a short-term, a high-dose of selenite caused more pronounced oxidative stress, greater liver injury, and prominent retardation of growth as compared to Nano-Se.