title: Dose-dependent promoting effect of polychlorinated biphenyls on enzyme-altered islands in livers of adult and weanling rats.
abstract: The effect of the technical mixture of polychlorinated biphenyls (PCBs) Clophen A 50 on the appearance of enzyme-altered islands initiated by diethylnitrosamine (DEN) in livers of 6 and 3 weeks old female Sprague-Dawley rats was studied. The loss of adenosine-5'-triphosphatase (ATPase), the emergence of gamma-glutamyltranspeptidase (GGTase), and the glycogen storage were used as histochemical markers. Islands were initiated by gastric intubation of 12 X 8 mg DEN/kg body weight/day in adults, or with 1 X 8 mg DEN/kg body weight in weanlings. Clophen A 50 alone initiated only few islands. A dose-dependent enhancement in number and area of islands by an additional treatment with Clophen A 50 of DEN-pretreated animals (2-100 mg/kg body weight/weekly, for 7 weeks) was observed in both age groups. In adults, doses between 2 and 100 mg/kg body weight increased number and area of ATPase-deficient islands 2 to 12-fold. In weanlings, application of 10-100 mg/kg body weight resulted in an increase of number and area up to 7- and 12-fold, respectively. No promoting effect was found with 2 mg/kg body weight compared to DEN-treated weanlings. The number of islands with coincidence of the three histochemical markers was enhanced dose-dependently in adults, and less marked also in weanlings after the application of the promoter.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D004052:Diethylnitrosamine / Q000633:toxicity; D005260:Female; D008099:Liver / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D008112:Liver Glycogen / Q000378:metabolism; D011078:Polychlorinated Biphenyls / Q000633:toxicity*; D051381:Rats; D011919:Rats, Inbred Strains; D005723:gamma-Glutamyltransferase / Q000378:metabolism*
chemical_list: D008112:Liver Glycogen; D004052:Diethylnitrosamine; C025647:clophen A50; D011078:Polychlorinated Biphenyls; D005723:gamma-Glutamyltransferase; D000251:Adenosine Triphosphatases