Tl(I) and Tl(III) differentialy affect the antioxidant defense system in PC12 cells

PUGA MOLINA, L. C.; VERSTRAETEN, S.V

Potrero de Los Funes, San Luis

Congreso; XLVII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2011

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Previously, we demonstrated that the exposure of rat pheochromocytoma (PC12) cells to a single dose of Tl(I) or Tl(III) (10-100 μM) resulted in an early oxidative stress status due to higher mitochondrial H2O2 production. In the current work we evaluated the effects of a short-term exposition (6 h) to Tl(I) or Tl(III) (10-100 μM) affected PC12 cells antioxidant defensesystem, measuring the expression and activity of the enzymes catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR). While CATexpression was not affected by Tl, a significant and concentrationdependent decrease in its activity was observed for both cations. Mn-SOD expression was increased in Tl(I)-treated cells, anddecreased in Tl(III)-treated cells. Total SOD activity was increased by Tl(I) (10-25 μM), while higher Tl(I) concentrations or Tl(III) decreased its activity. Accordingly to its function as H2O2 metabolizing enzyme, GPx activity was increased regardless the cation assessed. However, GR activity was slightly increased only in cells exposed to Tl(III). These results suggest an earlymisbalance between H2O2 production and degradation in Tl-exposed cells, effect that could be partially responsible for the toxic effects of these cations.