Subchronic toxicity of pentachlorobiphenyl congeners n. 126 or 118 in the rat liver. An electron microscope study.
3,3',4,4',5-Pentachlorobiphenyl (PCB) or congener n. 126 and 2,3',4,4',5-pentachlorobiphenyl or congener n. 118 were given independently to male and female Sprague-Dawley weanling rats. Experimental diets were prepared by dissolving the congeners in 4% corn oil. The congeners were administered as follows: congener n. 126--groups of three animals, either male or female, in each group were placed on the respective diets containing 0.1, 1.0, 10.0 ppb congener, 5.0 micrograms/kg bw loading dose + 10.0, or 100 ppb; congener n. 118--the females were dosed with 2, 20, 200, and 2,000 ppb congener, and the males received 10, 100, 1,000, 10,000 ppb. Thirteen weeks after the start of dosing with the two congeners, liver samples were obtained from all the animals and prepared for electron microscopy. In the congener n. 126-exposed animals, the alterations noted in a dose-related fashion consisted of a marked increase in the profiles of smooth endoplasmic reticulum (SER), and in the heightened number of lipid droplets in many parenchymal cells. Mitochondria showed abnormalities such as dumb-bell shapes, and the cristae parallel to the long axis of the organelle. Lipofuscin granules were numerous in the liver of animals that received 100 ppb of the congener; notably the females of the treatment group expressed this trait more abundantly than the males of the group. We conclude that the compound is mildly toxic. In the animals administered congener n. 118, the alterations were revealed in the liver of both male and female animals in a dose-related manner, also the most evident hepatocyte architectural modifications included an augmentation of SER profiles, mitochondrial aberrations, and an elevated number of lysosomal elements and lipid droplets. Abnormal shapes, and cristae in atypical orientation comprised mitochondrial aberrations. Alterations in the liver morphology of the females were qualitatively similar to those in the males; however, the dose levels used in the latter were five-folds of that which were given to the females. We conclude that the females are more sensitive than the males of the species to congener n. 118. We further conclude that congener n. 118 is less toxic than n. 126 since the lesions were induced by several-folds high dose levels used for the former.
Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Canada.
K
K
MacLellan
A
A
Singh
I
I
Chu
R
R
Poon
D C
DC
Villeneuve
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000648:ultrastructure; D005260:Female; D008055:Lipids / Q000032:analysis; D008099:Liver / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure*; D008297:Male; D008854:Microscopy, Electron; D008928:Mitochondria / Q000648:ultrastructure; D011078:Polychlorinated Biphenyls / Q000633:toxicity*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012727:Sex Characteristics; D013997:Time Factors
D008055:Lipids; C070055:2,3',4,4',5-pentachlorobiphenyl; D011078:Polychlorinated Biphenyls; C023035:3,4,5,3',4'-pentachlorobiphenyl