Abstract
The effect of 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) was studied on the activities of arylhydrocarbon hydroxylase, ethoxycoumarin deethylase, cytochrome c reductase, epoxide hydratase, UDP glucuronosyltransferase, and glutathione S-transferase in the liver, kidney, lung, small intestinal mucosa, and testis of male Wistar rats. There was a severalfold increase in the activity of monooxygenase in the liver, kidney, and lung, whereas virtually no effect could be detected in the intestine or testes. The proportion of 3- and 9-hydroxylation of the total hydroxylation of benzo( a)pyrene decreased in the liver, but increased in the kidney. TCDD had no significant effect on epoxide hydratase or glutathione S-transferase activities in any tissues. UDP glucuronosyltransferase exhibited a sevenfold increase in the liver, less than twofold in the kidney, and none in other tissues. Treatment of the microsomes with digitonin, trypsin, or phospholipase A did not reveal additional induction UDP glucurnosyltransferase, although all were able to increase measurable enzymatic activity in control and TCDD-treated animals. TCDD seems to be different from phenobarbital and polycyclic hydrocarbons as an effector of not only monooxygenase but also epoxide hydratase, UDP glucuronosyltransferase, and glutathione S-transferase.
Published Version
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