Effect of PCB (polychlorobiphenyls) on on L-ascorbic acid, pyridoxal phosphate and riboflavin contents in various organs and on hepatic metabolism of L-ascorbic acid in the rat.

Effects of continuous oral administration of PCB (polychlorobiphenyls, 10-100 mg/kg/day, 4 weeks) on tissue levels of L-ascorbic acid (vitamin C), pyridoxal phosphate and riboflavin (vitamin B2) in various organs and on hepatic metabolism of L-ascorbic acid were examined in male Wistar rats weighing 150-250 g. Riboflavin contents in the liver, kidney, brain, heart and testis were not altered by PCB treatments, whereas the hepatic level of pyridoxal phosphate, a biologically active form of vitamin B6, was significantly reduced by PCB administration. Under the same experimental conditions, L-ascorbic acid contents in the liver, kidney, lung and testis showed a significant increase. Histochemical studied revealed that in the adrenal gland, increase of L-ascorbic acid was localized in the fasciculate and reticular zones of cortex, respectively. It was found that increase of L-ascorbic acid in the liver is caused predominantly by activation of biosynthesis at the steps of galactose to D-glucuronic acid and is not due to changes in the catabolic processes of L-ascorbic acid per se. Possible significance of these changes in tissue levels and/or metabolism of vitamins in the occurrence of PCB intoxication is briefly discussed.