Effects of pesticides on metabolism of steroid hormone by rodent liver microsomes.

Liver microsomal steroid hydroxylating enzymes and prostatic testosterone-5alpha-reductase were studied in rat and mouse. Organochlorine and organophosphate pesticides tended to inhibit liver steroid hydroxylations, while carbofuran slightly stimulated them. Neither species was consistently more sensitive to pesticide effects than the other. All the pesticides bound to cytochrome P-450, producing Type I spectral changes. Values of Ks ranged from 1.9 to 8.7 mM for organochlorine and organophosphate compounds. Affinity for carbofuran was much lower (Ks=100-200mM).