Changes in oestrogen metabolism induced in rat liver microsomes by subcutaneous pellets of oestrone and testosterone

Oestrone administered in the form of subcutaneous pellets produced marked changes in the metabolism of [14C]oestradiol by male rat liver microsomes. The high yield of both 2-hydroxyoestradiol and water-soluble metabolites was decreased to the level normally observed in females and this effect was induced by relatively small amounts of oestrogen within a few days after implantation. The action of testosterone on the hepatic metabolism of oestrogens was also investigated together with the effect of removing the hormone pellets at different time intervals. In addition, the rate of absorption of the steroids was determined by direct weighing and, in the case of oestrone, controlled by using radioactive pellets of known specific activity.