Vitamin A status, polybrominated biphenyl (PBB) toxicosis, and common bile duct hyperplasia in rats

The interaction between dietary concentrations of vitamin A and PBB was evaluated in two experiments. In the first experiment, male weanling rats were used in a 2 X 3 factorial experiment. Concentrations of PBB were 0, 10, or 100 mg/kg of diet and diets were either vitamin A-deficient or were supplemented with 3000 IU vitamin A palmitate/kg of diet. In the second experiment the design was similar except that two vitamin A-supplemented diets were used, one containing 3,000 IU/vitamin A palmitate/kg of diet and the other 30,000 IU. Diets contained either 0 or 100 mg of PBB/kg. Clinical signs of vitamin A deficiency and mortality occurred early in rats fed vitamin A-deficient diets containing 100 mg of PBB/kg. Vitamin A supplementation provided partial protection against decreased weight gain associated with PBB. Decreases in thymic weight associated with PBB toxicosis were prevented by supplementation with vitamin A. Massive enlargement of the common bile duct occurred in rats fed a vitamin A-deficient diet containing 100 mg of PBB/kg. Histologically, this lesion consisted of extensive hyperplasia. A significant decrease in retinol concentrations in the sera was recorded in rats fed vitamin A-deficient diets containing 100 mg of PBB/kg. Interaction between vitamin A deficiency and PBB toxicosis affected vitamin A metabolism as manifested by the appearance of appreciable amounts of retinyl acetate in the liver vitamin A profile. These results suggest an interaction between PBB toxicity and vitamin A and emphasize the importance of nutritional factors such as vitamin A in assessment of PBB toxicosis.