OXIDATIVE STRESS TO DNA, PROTEIN, AND ANTIOXIDANT ENZYMES (SUPEROXIDE-DISMUTASE AND CATALASE) IN RATS TREATED WITH BENZO(A)PYRENE

Oxidative DNA damage (as 8-hydroxydeoxyguanosine; 8-OHdG), carbonyl co ntent of proteins, and activities of superoxide dismutase (SOD) and ca talase were investigated in female Sprague-Dawley rats orally treated with benzo(a)pyrene (B(a)P) (75 mg/rat). HPLC-ECD system showed that B (a)P increased the level of 8-OHdG in tissues (liver, kidney, and lung ), but a statistical significance was observed only in the liver (3.5- fold increase) and kidney (two-fold increase). In the liver, the peak level (21 +/- 5 8-OHdG residues/10(5) dG) was obtained 12 h after trea tment and returned close to control level (9 +/- 2 8-OHdG residues/10( 5) dG) at 24 h, but 8-OHdG was persistent in the kidney. Carbonyl cont ents measured as an index of protein oxidation were slightly increased (23 similar to 35%) in the cytosolic fraction of tissues, but a signi ficant increase (2.19 nmol/mg protein, 35% increase) was observed only in the liver 6 h after treatment, similar to 8-OHdG. However, the rat e of increase was relatively low compared to that of 8-OHdG. In contra st to DNA and protein damages, the activities of SOD and catalase in t he tissues were decreased after treatment (P < 0.01) and gradually inc reased to control levels. SOD and catalase activities in organs of rat s were inversely correlated with oxidative damages to DNA and protein. The data suggest that B(a)P oxidatively altered DNA, protein, and ant ioxidant enzymes in rats and this might be associated with B(a)P carci nogenesis. (C) 1997 Elsevier Science Ireland Ltd.