Comparative Enzyme Induction and Lindane Metabolism in Rats Pre-treated with Various Organochlorine Pesticides

Abstract

1. The comparative effect of 7 days pre-treatment with one of seven organo-chlorine pesticides on the metabolism of lindane in vivo and on the metabolism of EPN, p-nitroanisole and methyl orange in vitro was investigated.2. Mirex was the most potent inducer of the oxidative hydrolysis of EPN, the O-demethylation of p-nitroanisole and the azo reduction of methyl orange. Chlordane and DDT were equipotent followed by hexachlorobenzene, toxaphene, pentac and penphene. Enzyme activity of rats pre-treated with the latter three pesticides was not significantly higher than that of controls.3. DDT stimulated significantly greater metabolism of lindane than did pre-treatment with any of the other six pesticides. In general DDT, mirex, chlordane and hexachlorobenzene were the most effective activators of lindane metabolism followed by toxaphene, pentac and penphene. Only pre-treatment with penphene failed to stimulate a significantly higher excretion of radio-labelled lindane metabolites than that excreted by controls.4. Comparative differences in lindane metabolism in vivo were not adequately reflected by the determination of enzyme activities in vitro.5. Pre-treatment with organochlorine pesticides altered lindane metabolism by selective effects on specific metabolic pathways.