Steroidogenic effects of luteinizing hormone and prolactin on the rat ovary in vivo

Progesterone and 20α-dihydroprogesterone were measured in the ovarian venous blood of rats in early pro-oestrus, late dioestrus, day 5 of pseudopregnancy, and in androgen-treated animals with persistent oestrus. Little progesterone was secreted in early pro-oestrus or persistent oestrus (0·1 μg./hr.), but the secretion rose in dioestrus (2·1 μg./hr.) and in pseudopregnancy (7 μg./hr.). The 20α-dihydroprogesterone secretion was low in the persistent oestrous group; in all the other groups it was 1·5–3 μg./hr.

Treatment with luteinizing hormone increased progesterone secretion within 30 min. in pro-oestrus and persistent oestrus, had no significant effect in dioestrus, and depressed it markedly in pseudopregnancy. It appeared to have no significant effect on 20α-dihydroprogesterone secretion except during pseudopregnancy, when it was depressed.

Treatment with prolactin produced no effect within 30 min.in pro-oestrous, dioestrous or pseudopregnant animals.

Studies on the biosynthesis of 16-dehydro steroids. The metabolism of [4-14C]pregnenolone by boar adrenal and testis tissue in vitro

1. The metabolism of [4-(14)C]pregnenolone in vitro by boar adrenocortical and testis tissue has been studied. 2. Boar testis tissue formed three labelled Delta(16)-steroids, 5alpha-androst-16-en-3alpha-ol, 5alpha-androst-16-en-3beta-ol and androsta-4,16-dien-3-one. In adrenal tissue very much smaller yields of the same metabolites were obtained. 3. Both tissues produced labelled progesterone, androst-4-ene-3,17-dione and testosterone in varying quantities. The amount of progesterone was about 120 times greater in the adrenal tissue. In testis tissue dehydroepiandrosterone was found only in small quantity. 4. A pathway is suggested for the biosynthesis of Delta(16)-steroids from pregnenolone in boar testis tissue. The possibility that progesterone may be an intermediate is discussed.

Biosynthesis of cholestanol: 5-alpha-cholestan-3-one reductase of rat liver

The 3-beta-hydroxysteroid dehydrogenase of rat liver which catalyzes the conversion of 5alpha-cholestan-3-one to 5alpha-cholestan-3beta-ol is localized mainly in the microsomal fraction. The enzyme required NADPH as hydrogen donor and differed from the known 3-beta-hydroxysteroid dehydrogenases of the C(19) series in being inactive in the presence of NADH. The microsomal preparations did not reduce the 3-keto groups of cholest-4-en-3-one, cholest-5-en-3-one, or 5beta-cholestan-3-one to the corresponding 3beta-hydroxy compounds. The conversion of 5alpha-cholestan-3-one to 5alpha-cholestan-3beta-ol was only slightly inhibited by the reaction product or by other monohydroxy steroids, but a strong inhibitory effect was noted with cholest-5-en-3-one, 5alpha-cholestane-3beta, 7alpha-diol and 5alpha-cholestan-7-on-3beta-ol. The microsomes, but not high speed supernatant solution, catalyzed the reverse of the cholestanone reductase reaction, namely the conversion of 5alpha-cholestan-3beta-ol to 5alpha-cholestan-3-one in the presence of oxygen and an NADP-generating system. The action of the microsomal preparations upon 5alpha-cholestan-3-one produced 5alpha-cholestan-3alpha-ol in addition to the 3beta-epimer. The 3-alpha-hydroxysteroid dehydrogenase involved functioned with either NADH or NADPH as hydrogen donor. The ratio of 5alpha-cholestan-3beta-ol to 5alpha-cholestan-3alpha-ol formed from 5alpha-cholestan-3-one was approximately 10:1 and was independent of the sex of the animal from which the microsomes were prepared.

Steroid biosynthesis in vitro by tissue from a granulosa cell multilocular cystadenoma

A granulosa cell multilocular cystadenoma was removed from a 7-yr.-old girl who showed breast growth and had a history of almost continuous vaginal bleeding for 9 days. Tissue, which microscopically was shown to consist almost exclusively of granulosa cells, was incubated with [4-14C]-DHA and [7-3H]pregnenolone in Krebs-Ringer bicarbonate solution. The ability of this tissue to synthesize oestrogens from these precursors was investigated. These results and those of pre- and post-operative urinary steroid estimations are discussed in relation to current theories of steroid biosynthesis.

In vitro steroidogenesis in normal human ovarian tissue

Eleven samples of normal human ovarian tissue from the various phases of the cycle were incubated with 7-3H progesterone and 4-14C-5-pregnenolone. Isolation, identification and quantitation of the metabolites showed clearly that pregnenolone is a far better substrate than progesterone for the production of C19 steroids. Under the conditions of these incubations, 3β-ol dehydrogenase enzyme activity converted the majority of the metabolites into androstenedione. The accumulation of radioactive androstenedione at the end of the incubation exceeded that of testosterone except in the later part of the luteal phase.