Bioaccumulation of tetra-through octachlorinated dibenzo-p-dioxins in two different mixtures and their biochemical effects on enzymes of carbohydrate metabolism in mice

Abstract

Two different mixtures of various PCDD homologues and congeners originating from octachlorodibenzo-p-dioxin by dechlorination were administered by oral gavage once a week to C57BL/6J (B6) and DBA/2J (D2) mice, respectively, for up to 15 weeks followed by a short recovery period. Each mouse strain was tested with two different doses of these mixtures as well as with 2,3,7,8-TCDD. Neither the clinical symptoms nor the development of body weight varied from those observed in control animals. Liver weight increased in a dose-dependent manner, and significant treatment-specific thymus involution was observed. TCDD and most of the 2,3,7,8-congeners reached steady state concentrations in the liver approximately 10 weeks after starting the administration. Modulations in carbohydrate metabolism were observed in the liver under the influence of all treatments. Investigation of epidermal metabolism revealed signs of hyperproliferation as evidenced by an increase in ornithine decarboxylase activity and of thymidine triphosphate incorporation in B6, but not in D2 mice.