Conversion of labelled cholesterol to neutral steroids by human ovaries perfused in vivo.

Abstract

ABSTRACT Four human ovaries in mid-luteal phase have been perfused with tritium labelled cholesterol through the cannulated ovarian artery for thirty minutes. Three 15-min samples of ovarian venous blood have been collected, two during the perfusion and the third in the following 15 min. In two cases, 15 min after the beginning of the perfusion, highly purified human urinary LH was rapidly injected into the ovarian artery. The ovarian tissue and the three fractions of venous blood were analysed for phenolic and neutral steroids. In the ovarian tissue only progesterone (4-pregnene-3,20-dione), pregnenolone (3β-hydroxy-5-pregnen-20-one) and 17α-hydroxyprogesterone (17α-hydroxy-4-pregnene-3,20-dione) were isolated. The amount of progesterone isolated from the two ovaries injected with LH was five times higher as compared with the other two ovaries. No steroids were present in the samples of venous blood except in the two cases in which LH was injected, where progesterone was isolated only in the third sample. It is concluded that circulating cholesterol is utilized by the ovary at the mid-luteal phase for the synthesis of C21 steroids and that the presence of LH increases the production and the release of progesterone by the ovary.