Alpha-foetoprotein and oestrogen metabolism. I. -Influence of alpha-foetoprotein on the metabolism of steroids by rat liver microsomes in vitro.

Rat alpha-foetoprotein (AFP) was shown to inhibit the formation of water soluble metabolities of oestrone and oestradiol by incubation with microsomes from rat liver in the presence of NADPH. The results support the proposal that in young animals the low activity of enzymes responsible of oestradiol metabolism may be due in part to the presence of AFP and not only to the low level of these enzymes.