COMPARATIVE TOXICITY OF POLYCHLORINATED BIPHENYL AND POLYBROMINATED BIPHENYL IN THE RAT-LIVER - LIGHT AND ELECTRON-MICROSCOPIC ALTERATIONS AFTER SUB-ACUTE DIETARY EXPOSURE

  • 1 January 1978
    • journal article
    • research article
    • Vol. 1  (3) , 241-257
Abstract
The comparative toxicity of polychlorinated biphenyl (PCB) and polybrominated biphenyl[PBB] in livers was studied in male Holtzman rats. Animals (4 wk old) were fed at dietary levels of 0, 5, 50 or 500 ppm for 5 wk and then sacrificed. The mean liver-body weight ratios of the 50 and 500 ppm groups were increased. Histopathologic examination of the livers revealedfatty degenerative change associated with both compounds. This change was more marked at 500 than at 50 ppm. Various sized lamellar cytoplasmic inclusions were detected in livers of animals fed 500 ppm of either compound. The inclusions were more numerous in the PBB-treated rats. Several animals fed 50 ppm PBB had a few inclusions. In rats that received 500 ppm PBB, hypertrophic degenerative hepatocytes were present around the central veins. On the periphery of this change there were occasionally multinucleated hepatocytes. EM examination at a dose level of 5 ppm in the PCB and PBB groups showed a slight proliferation of smooth endoplasmic reticulum (SER), a moderate increase of lipid droplets and some liposomes, and a marked proliferation of Golgi condensing vesicles containing lipoprotein particles. A decreased number of mitochondria and lysosomes was observed. At 50 ppm, similar but more marked ultrastructural alterations were seen. An increased number of branched and cup-shaped profiles of mitochondria and a decreased number of Golgi condensing vesicles containing lipoprotein particles were observed. Concentric membranous cytoplasmic whorls were encountered only in the 50 ppm PBB-treated rats. At 500 ppm the number of mitochondria decreased in both groups. There was a marked increase in the number of SER and liposomes concomitant with a decreased number of Golgi condensing vesicles containing lipoprotein granules. Membranous whorls were present in the 500 ppm groups.