In vivo effects of inorganic mercury (HgCl2) on striatal dopaminergic system

In the present study, the effects of intrastriatal administration of differ ent concentrations (40 muM, 400 muM, and 4 mM) of inorganic mercury (HgCl2) on the dopaminergic system of rat striatum were evaluated, using a microdi alysis technique coupled to liquid chromatography-electrochemical detection . In previous studies, we discussed the effects of organic mercury (MeHg) a dministration on the striatal dopaminergic system on the basis of changes i n the release and metabolism of striatal dopamine (DA), In the present stud y it is demonstrated that intrastriatal administration of all concentration s of HgCl2 produced significant increases in the output of DA (1.240, 2500, and 2658% for the concentrations of 30 muM, 400 muM, and 4 mM HgCl2, respe ctively) from rat striatal tissue, associated with significant decreases in striatal levels of its metabolites dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) with the concentrations of 400 muM and 4 mM HgCl2 ( 74.4 and 3.4% for DOPAC and 71.0 and 50.6% for HVA, respectively), whereas no changes in metabolite levels mere observed with the concentration of 40 muM HgCl2. These effects are explained as a result of stimulated DA release and/or changed DA metabolism. The effects of intrastriatal administration of HgCl2 were compared with those of MeHg on DA extracellular levels. (C) 2 001 Academic Press.