DDT and its metabolite DDE alter steroid hormone secretion in human term placental explants by regulation of aromatase activity

Placental explants were used to compare the effects of two isomers of DDT (1,1,1,-trichloro-2,2-bis(p-chlorophenyl)ethane), p,p′-DDT and o,p′-DDT and their metabolites p,p′-DDE and o,p′-DDE (1,1,-dichloro-2,2-bis(p-chlorophenyl)ethylene) on steroid hormone secretion (estradiol (E2) and progesterone (P4)). Explants were treated with 1, 10, 100 ng/ml or 1 μg/ml of each compound for 24 h. We found that all investigated compounds at all doses caused reductions of estradiol secretion. Moreover, it was shown that the inhibition of estradiol secretion was due to direct action on aromatase activity. Twenty-four-hour exposure to p,p′-DDE, o,p′-DDT or o,p′-DDE at doses of 100 ng/ml or 1 μg/ml increased P4 secretion, suggesting that these compounds act on P450scc. The fluorometric assay confirmed that all investigated compounds inhibited aromatase activity at a concentration of 100 ng/ml. Our findings suggest that by decreasing estradiol secretion with concomitant stimulation of progesterone secretion, DDT could be a factor that influences the outcome of pregnancy.