Increase of Hepatic and Serum Aldehyde Dehydrogenase Activity after TCDD Treatment

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), a contaminant of some herbicides, is an extremely potent enzyme inducer. Male albino rats of two genetically different substrains developed for the inducibility (RR) and non-inducibility (rr) of aldehyde dehydrogenase by phenobarbital were given TCDD 80 μg/kg as a single dose 6 days before analysis. rr-Animals having no induction of the hepatic soluble high-Km aldehyde dehydrogenase by phenobarbital showed an approximate 25-fold increase in activity after TCDD treatment. The increase in aldehyde dehydrogenase activity could be detected only when measured with a millimolar substrate concentration. The aldehyde dehydrogenase activity in serum was increased 3-fold after TCDD administration in both substrains.