Modulation of the hepatic antioxidant defense system by air polluants from urban areas

RESUMO

This study describes the changes induced by organic extracts from airborne particuiate matter in some enzymes related to the antioxidant defense system as well as in peroxisomal acyl CoA oxidase activity in rat liver. After 48 h of i.p. injection (40 mg/kg b.wt.) the hepatic GSH content decreased by about 30 per cent, which was accompanied by a parallel increase in glutathione-S-transferase activity. In contrast the activity of glutathione peroxidase was significantly decreased (p < 0.05).Peroxisomal acyl CoA-oxidase was enhanced by about 40 per cent with a parallel increase of liver catalase (27 per cent), the peroxisomal H2O2-destroying enzyme. With the only exception hepatic lipid peroxidation, that remains unchanged, all the effects showed a dose-dependent response with respect to the content of polycyclic aromatic hydrocarbons in the organic airborne extracts. However, the content of other chemical pollutants such as plasticizers, pestcides and other organic compounds must be taken into account. These results suggest that organic extracts from Santiago airborne particles might induce a prooxidant state. According to this view the increase in GSTs and catalase activity may be considered as a protective response against the damage induced by airborne pollutants.