EFFECTS OF PROBUCOL ON HYPERCHOLESTEROLEMIA-INDUCED CHANGES IN ANTIOXIDANT ENZYMES

Effects of high cholesterol diet (0.5% and 1%) on the activity of anti oxidant enzymes [superoxide dismutase (SOD), catalase (CAT) and glutat hione peroxidase (GSH-P-x)] in the aortic tissue of rabbits were inves tigated in the absence or presence of probucol (0.5 gm/kg daily, orall y). Five groups of ten rabbits each were studied. Group I, regular rab bit chow diet; Group II, chow + 0.5% cholesterol; Group III, chow + 0. 5% cholesterol + probucol; Group IV, chow + 1% cholesterol and Group V , chow + 1% cholesterol + probucol. The aorta was removed at the end o f 4 months for measurement of the antioxidant enzymes. An increase in activity of aortic antioxidant enzymes was noted in cholesterol-fed ra bbits (Groups II and IV), being similar for SOD and catalase but highe r for GSH-P-x in Group IV as compared to Group II. Probucol was ineffe ctive in altering this cholesterol-induced increase in enzyme activity except in Group III where it increased the activity of GSH-P-x. These results suggest that aortic antioxidant enzymes are affected in hyper cholesterolemia and that probucol is ineffective in altering the aorti c antioxidant enzyme activity except GSH-P-x activity which increased in 0.5% cholesterol-fed The protective effects of probucol against hyp ercholesterolemic atherosclerosis may be partly due to an increase in the GSH-P-x activity at low levels of hypercholesterolemia. At higher levels of hypercholesterolemia, the protective effects of probucol cou ld be due to its antioxidant activity.