“…Mercury causes depletion of the principal cellular antioxidants, with high affinity for the thionic group (Azevedo, 2003), the functional group of the amino acid, cysteine. Beyond effects on the retinal cell (eg, Bonci et al, 2006), various other cells of the nervous system appear to be affected by exposure to the metal (Nascimento & Chasin, 2001). The observation that methylmercury induces oxidative stress in the brain of house mice (Yee & Choi, 1994) led Aschner et al (1995Aschner et al ( , 1998Aschner et al ( , 2000 to consider that there are two critical components in the neurotoxicology of methylmercury: the increase in extracellular concentration of glutamate as a result of alterations in the astrocyte function (Aschner, Vitarella, Allen, Conklin, & Cowan, 1998), as well as direct interaction with the cysteine transporter, causing a decrease in the concentration of cysteine for synthesis of glutathione; and interference with the function of the astrocyte transporter of glutamate, causing an increase in the extracellular concentration of this neurotransmitter (Morken, Sonnewald, Aschner, & Syversen, 2005); this activity is modulated by adenosine (Aschner, Mullaney, Wagoner, Jr., Lash, & Kimelberg, 1995) and by glutathione (Kaur, Aschner, & Syversen, 2006).…”