Probucol increases glutathione peroxidase-1 activity and displays long-lasting protection against methylmercury toxicity in cerebellar granule cells

El pdf del artículo es el manuscrito de autor.Methylmercury (MeHg) is an environmental neurotoxicant whose molecular mechanisms underlying toxicity remain elusive. Here we investigated molecular events involved in MeHg-induced neurotoxicity in cultured cerebellar granule cells (CGCs) as well as potential protective strategies for such toxicity. Glutathione peroxidase (GPx-1) activity was significantly (p = 0.0017) decreased at 24 h before MeHg-induced neuronal death (day in vitro 4). This event was related to enhanced susceptibilities to hydrogen- or tert-butyl-peroxides and increased lipid peroxidation. However, intracellular calcium levels, glutamate uptake and glutathione levels, as well as glutathione reductase and catalase activities, were not changed by MeHg exposure at this time-point. Probucol (PB), a lipid-lowering drug, displayed a long-lasting protective effect against MeHg-induced neurotoxicity. The beneficial effects of PB were correlated to increased GPx-1 activity and decreased lipid peroxidation. The protection afforded by PB was significantly higher when compared to the antioxidants ascorbic acid and trolox. In vitro studies with the purified GPx-1 proved that MeHg inhibits and PB activates the enzyme activity. Overexpression of GPx-1 prevented MeHg-induced neuronal death. These data indicate that (i) GPx-1 is an important molecular target involved in MeHg-induced neurotoxicity and (ii) PB, which increases GPx-1 activity in CGCs, induces enduring protection against such toxicity. The results bring out new insights on the potential therapeutic strategies for poisonings to MeHg and other pathological conditions related to increased production and/or decreased detoxification of peroxides.This study was supported by the Grant FIS PI061212 and 2005-SGR-00826 (Ministry of Health and Generalitat de Catalunya, respectively, Spain). Marcelo Farina was recipient of a post- doctoral fellowship (Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPq/201362/2007-4) and received financial support from CNPq (479239/2007-0) and FAPESC (Jovens Pesquisadores - FAPESC/CNPq 04/2007).Peer reviewe