, 1992, Kajiwara et al., 1996, Simmons-Willis et al., check details 2002, Adachi, 2006 and Yin et al., 2008). Corroborating this hypothesis, our group recently reported that mice chronically treated with the MeHg–Cys complex show enhanced Hg uptake, especially in the liver, when compared

to other organs, such as the brain and kidney (Roos et al., 2010). These results are most likely due to the fact that the liver is a central organ of protein metabolism and receives amino acids absorbed at the intestinal levels as well as those derived from other organs and systems (Duarte, 2003). Although hepatic cells contain some of the same carriers that have been implicated in the transport of Hg in other organs, the precise mechanisms underlying the MeHg uptake across the membrane into normal hepatocytes as well as the influence of the MeHg–Cys complex on Hg uptake and hepatoxicity have not previously been well defined. Consequently, our study was primarily designed to investigate the Hg content in hepatic cells, at both cytosolic and mitochondrial levels after exposure to MeHg or the MeHg–Cys complex. Several previous studies have investigated and reported on the toxicology of MeHg, but, to date, only chelating agents have been employed to facilitate

SB203580 the removal of Hg from the body (Pingree et al., 2001 and Carvalho et al., 2007). However, these drugs are of limited use because of their adverse side effects. In the present study, we have tested the possible use of Met as an efficacious agent capable of protecting against the deleterious effects of MeHg. We observed that the Hg concentration in liver slices and in the mitochondria isolated from liver slices was higher after exposure to the MeHg–Cys complex (Fig. 1). Notably, we observed that Met decreased MeHg uptake by liver slices (Fig. 1). These results are different from those reported by Adachi (2006) after exposure of mice to MeHg. Adachi reported that Met can increase the hepatic deposition of Hg 2 h

after intravenously administration of MeHg and/or methionine. Since we have used only a single time-point of exposure of liver slices to MeHg (30 min) and/or Met (45 min), Fenbendazole we cannot disregard the possibility that uptake of MeHg could be increased in the presence of Met. Alternatively, the decrease in Hg uptake in the slices by Met may be, at least in part, related to the relatively high concentration of Met in the medium and, consequently, to direct interaction between MeHg and Met, thus lowering the effective free concentration of MeHg. Accordingly, we can posit that the effect observed in the presence of Met may be related to a direct interaction of the sulfur atom and/or amino end of Met with MeHg (Rabenstein and Fairhurst 1975). Alternatively, Met may be reducing the uptake of MeHg complexed with endogenous cysteine in liver slices. In addition, here we have worked with an in vitro system derived from rats.