3,4,3',4'-Tetrachlorobiphenyl-Induced Effects in the Rat Liver. I. Serum and Hepatic Retinoid Reduction and Morphologic Changes

Abstract

The distribution of 3,4,3',4'-tetrachlorobiphenyl (TCB), its effects on serum and hepatic retinoid content, and liver morphology were investigated in adult female WAG/Rij rats. Animals received a single intraperitoneal injection of either a corn oil vehicle, 15 or 200 mg TCB/kg body weight and were killed at 1, 3, 7, and 14 days after treatment. One rat of the high-dose group that had received 200 mg TCB/kg containing 1.85 mCi of 3H-TCB was sacrificed at each sampling time. There was a significant increase in liver weight when expressed as a percentage of body weight in the high-dose group at day 3 (122% of controls), day 7 (116% of controls), and day 14 (110% of controls). There was a rapid rise in the amount of 3H-TCB present in the liver that peaked at day 7 followed by a rapid decline in the amount of radiolabeled material by day 14. Greater than 90% of the radiolabeled material in the liver was parent compound. TCB treatment induced a significant decrease in serum retinol content in the high-dose group at day 3 (39% of controls) and day 7 (46% of controls) following exposure. There was a significant decrease in hepatic retinol content in the high-dose group at day 3 (34% of controls), day 7 (25% of controls), and day 14 (42% of controls) following exposure. TCB treatment induced a significant decrease in hepatic retinyl palmitatc content in the high-dose group at day 7 (56% of controls) following exposure. Ultrastructural alterations in hepatocytes included the proliferation and vesiculation of endoplasmic reticulum, and mitochondrial enlargement with paracrystalline inclusions. There was an associated change in the number, size, and distribution of lipid droplets in hepatocytes and fat-storing cells following exposure. The results of this study indicate that TCB treatment induces a marked reduction in serum and hepatic retinoid content accompanied by morphologic changes in liver cell populations.