The serum ferroxidase system and the effect of estrogen on plasma iron

Estrogen effects on plasma iron and ferroxidase activity in some mammals and domestic fowl are studied, to investigate a possible estrogen mechanism on iron through its action on the ferroxidase system. Although estrogen generally induces ceruloplasmin, iron mobilization, characterized by a rise in plasma iron, was evident only in rats and chickens. Gonadotrophin treatment confirmed these results. A decreasing affect on plasma iron was noted in rabbits and guinea-pigs, substantiated by some bibliographical data. Ferroxidase activity increased and a copper-dependent factor was evident in copper injected species. Iron mobilization, however, was produced only in rats and chickens. D-penicillamine treatment considerably lowered ferroxidase activity in rats and suppressed the estradiol increasing plasma iron effect. This response to the copper-chelating drug did not take place in the other species. This phenomenon could be explained by the presence of two copper-dependent ferroxidases (ferroxidase I or ceruloplasmin and ferroxidase II) in rat plasma, as recently published.