The effect of oestradiol-3N-bis-(2-chloroethyl)carbamate-17beta-phosphate (estracyt) on the 5alpha-reductase in the rat ventral prostate.

The ventral prostate of the rat both after in vitro incubation and in vivo experiments was found to contain appreciable 5alpha-reductase activity, whilst a very low activity was registered in the diaphragm and liver. Neither Estracyt nor LEO275 (Estracyt without the phosphate group in position 17 of the oestradiol moiety) had an inhibitory effect on the enzyme activity after in vitro incubation but equivalent amounts of oestradiol-17beta and oestradiol-17beta-phosphate significantly reduced 5alpha-reductase activity. When Estracyt was injected in vivo no influence on activity was registered in "short term" experiments while a significant inhibition was found after "long term" treatment in vivo. Possible explanations for this "long term" effect of Estracyt on 5alpha-reductase activity are discussed.