COMPARATIVE-STUDIES ON THE INDUCTION OF ETHOXYRESORUFIN O-DEETHYLASE BY 2,3,7,8-TCDD AND 2,3,7,8-TBRDD

Ethoxyresorufin O-deethylase (EROD) activity was measured in rat liver homogenates subsequent to a single subcutaneous injection of 2,3,7,8-tetrabromodibenzo-p-dioxin (TBrDD). The rate of induction was compared with that observed after treatment with the corresponding chlorinated substance (2,3,7,8-tetrachlorodibenzo-p-dioxin; TCDD) using the same experimental set-up. The time-dependence of the induction profile of EROD activity after treatment with 600 ng TBrDD/kg body wt was almost identical with that observed after an injection of 300 ng TCDD/kg body wt. When measured 7 days after the injection the extent of EROD induction was largely linear (in a double logarithmic plot) over the concentration range between 0.02 to 6 nmole TBrDD/kg body wt. The results of our studies indicate that TBrDD is a similarly powerful inducer of EROD in rat liver as TCDD. © 1990.