Toxicity of PCB 105 in the rat liver: an ultrastructural and biochemical study

PCB 105 (2,3,3',4,4'-pentachlorobiphenyl) congener was fed to weanling Sprague-Dawley rats in a diet combined with 4% corn oil. The animals were distributed randomly into 10 groups, each of which contained 10 males and 10 females, and rats in 8 groups received diets containing PCB at concentrations of 0.05, 0.5, 5, and 50 ppm. Animals in the other 2 groups served as controls. After 13 weeks, the animals were humanely killed and liver samples were obtained and prepared for transmission electron microscopy. Ultrastructural alterations revealed in the hepatocytes of animals fed the PCB included smooth endoplasmic reticulum proliferation, atypical mitochondrial cristae, and augmentation of peroxisome numbers (in animals fed high PCB concentrations). Biochemical alterations were estimated by using hepatic microsomal pentoxyresorufin-O-dealkylase (PROD) and ethoxyresorufin-O-deethylase (EROD) activities. A dose-dependent increase in EROD and PROD activities was discovered; only in the animals of highest PCB dose group, however, was EROD found to be significant (p < .05). Based on our previous work, this congener is relatively less toxic than PCB 126, 118, and 153 and is similar in toxicity to 156.