Histoenzymological studies of 3beta- and 17beta-hydroxysteroid dehydrogenases in the placentae and adrenal glands of bilaterally ovariectomized rats.

The distribution and activities of 5-unsaturated-3beta- and 17beta-hydroxysteroid dehydrogenases (HSD) have been studied during the pregnancy of normal and ovariectomized rats on days 17, 19 and 21 post coitum. No hormonal substitution was provided after bilateral ovariectomy on day 15 post-coitum. 5-Unsaturated-3beta-HSD was characterized with pregnenolone, 17alpha-hydroxypregnenolone and dehydroepiandrosterone as substrates; oestradiol-17beta and testosterone were used for the investigation of 17beta-HSD activity. With these substrates, it was found that the placental and adrenal activities and distribution of 5-unsaturated-3beta- and 17beta-HSD did not differ in ovariectomized and control rats and it is suggested that increased placental or adrenal steroidogenesis does not supplement deficient ovarian function in order to maintain pregnancy. In the pregnant rat, the ovaries do not control the activities of 5-unsaturated-3beta- and 17beta-HSD in the placenta.