Studies of catecholestrogen metabolism during normal pregnancy: changes of plasma catecholestrogen levels after DHA-S or E1-S injection

So as to evaluate metabolism of catecholestrogens during pregnancy, changes in plasma unconjugated estradiol (E2), estrone (E1), 2-methoxyestradiol (2-mE2) and 2-methoxyestrone (2-mE1) concentrations were measured after a bolus injection of 40mg of estrone-sulfate (E1-S) or 100mg of dehydroepiandrosterone-sulfate (DHA-S) to normal pregnant women near term. The injection of E1-S resulted in a marked rise in plasma 2-mE1 levels followed by a rapid marked increase in the plasma E1 concentration. The injection of DHA-S produced a small increase in the plasma 2-mE2 levels in spite of a marked increase in the plasma E2 concentration. No significant correlation between E2 and 2-mE2 was found, however, significant correlations between E1 and 2-mE1, between E1 and 2-mE2 and between 2-mE2 in in both groups were demonstrated. The marked increase in 2-mE1 compared to a small increase in 2-mE2 after DHA-S injection indicates that E2 may participate in the formation of catecholestrogen via its conversion to E1 during pregnancy. These results suggest that the main route for the formation of catecholestrogen is via E2----E1----(2OHE1)----2-mE1 in normal pregnancy near term.