INVITRO METABOLISM OF PROGESTERONE, 17-HYDROXYPROGESTERONE, AND 17,20-BETA-DIHYDROXY-4-PREGNEN-3-ONE BY OVARIES OF THE COMMON CARP CYPRINUS-CARPIO - PRODUCTION-RATES OF POLAR METABOLITES

[14C]Progesterone, 17-[3H]hydroxyprogesterone, and 17,20β-[3H]dihydroxy-4-pregnen-3-one (17,20βP) were incubated for 1, 3, 6 or 24 hr with ovaries from carp which had received injections of either carp pituitary extract or saline. All three substrates were very rapidly metabolized to polar products, but 17,20βP was not detected as a metabolite of either progesterone or 17-hydroxyprogesterone. The major metabolite in all incubations was very similar, but not identical, in chemical and chromatographic properties to 5β-pregnane-3α,6α,17,20β-tetrol. A compound isopolar with 5β-pregnane-3α,6α,17,20α-tetrol was isolated only in incubations of progesterone and 17-hydroxyprogesterone. It is suggested that hydroxylation and reduction may be a deactivation mechanism allowing 17,20βP to build up as an intermediate, and active maturation inducing steroid, only in response to the ovulatory gonadotrophin surge, thus assisting in synchrony of oocyte maturation. © 1990.