Time course of arsenic species in the brain and liver of mice after oral administration of arsenate.

The understanding of the biomethylation process of arsenic is essential to uncover the mechanisms of arsenic toxicity. This work analyzes the time course of arsenic species in the brain and liver of adult mice, after a single oral administration of three arsenate doses [2.5, 5.0 and 10 mg As(V)/kg]. Quantification of arsenic species was performed by means of liquid chromatography coupled to atomic fluorescence 2, 5, 8, 12 and 24 h after administration. The results show that 2 h after arsenate administration inorganic arsenic arrives to the liver and its concentration diminishes gradually until becoming non-detectable at 12 h. Arsenic takes longer to appear in the brain and it is present only as dimethyl arsinic acid. Since arsenic concentration decreases in liver while it increases in the brain, this suggests that the arsenic metabolite reaches the brain after formation in the liver. Importantly, the fact that dimethyl arsinic acid is no longer present after 24 h suggests the existence of a mechanism to clear this metabolite from brain tissue.