Long-Term Effects of Dietary Polychlorinated Biphenyl and High Level of Vitamin E on Ascorbic Acid and Lipid Metabolism in Rats

Abstract

Long-term feeding of purified diets containing (per kg diet) 100 mg of polychlorinated biphenyl (PCB) and 1000 mg of vitamin E (RRR-α-tocopheryl acetate) to male Wistar rats was carried out. Rats fed a diet containing PCB rapidly became hypercholesterolemic and maintained high cholesterol levels throughout the 240 d of the experiment. Rats fed a high dietary level of vitamin E plus PCB had higher serum cholesterol and lower liver cholesterol than rats fed a lower level of vitamin E plus PCB. In rats fed PCB, urinary excretion of ascorbic acid was higher than in rats not fed PCB. Urinary ascorbic acid was lower in rats fed high levels of vitamin E plus PCB than in those fed the normal levels of vitamin E plus PCB. Rats fed PCB had lower liver vitamin A storage and higher vitamin A in kidney than rats not fed PCB. This implies that a redistribution of vitamin A occurred in rats fed PCB. Histological observations revealed that central halves of the hepatic lobules of rats fed PCB showed distinct changes consisting of hypertrophy of hepatocytes in the perivenous region and accumulation of vacuoles (lipid droplets) in the cells in the remaining affected portion. Administration of a high dose of vitamin E could not ameliorate this lesion while the treatment depressed effectively the lipid peroxidation. This suggests that the lipid peroxidation was not responsible for the hepatic damage induced by PCB.