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

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

Potrero de 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 uM) 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 uM) affected PC12 cells antioxidant defense system, measuring the expression and activity of the enzymes catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR). While CAT expression was not affected by Tl, a significant and concentration-dependent decrease in its activity was observed for both cations. Mn-SOD expression was increased in Tl(I)-treated cells, and decreased in Tl(III)-treated cells. Total SOD activity was increased by Tl(I) (10-25 uM), 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 early misbalance between H2O2 production and degradation in Tl-exposed cells, effect that could be partially responsible for the toxic effects of these cations. This work was supported by grants of the University of Buenos Aires (B086) and CONICET (PIP 112-200801-01977), Argentina.