The Conversion of Pregnenolone to a More Active Progestational Substance by Incubation With Endocrine Tissues in Vitro

Abstract

Incubation of pregnenolone with minced beef corpora lutea resulted in conversion of the steroid to a more active progestational substance as shown by biological assay on the endometrium of the spayed rabbit. Control studies with non-incubated pregnenolone and corpus luteum incubated without steroid, injected separately and in combination, all yielded negative results.To exclude bacterial action, experiments were repeated under sterile conditions, but without diminution in conversion activity.Negative results were obtained when pregnenolone was incubated with spleen, liver or ovaries. The incubation of this steroid with beef adrenal and human placenta, however, resulted in active conversion.It is noteworthy that the adrenal appears to be even more active in the conversion of pregnenolone than the corpus luteum. The association exhibited by the adrenal gland of a lower progesterone content and greater conversion activity, as compared with the corpus luteum, points to progesterone as a likely intermediate substance in the synthesis of the adrenal corticoids.