Progesterone metabolism in human endometrial stromal and gland cells in culture

Metabolism of progesterone by human endometrium has been described, but the rapidity and extent of progesterone metabolism is incompletely documented in cellular fractions of normal endometrium. Therefore, we evaluated progesterone metabolism in separated stromal and gland cells in culture obtained from normal human endometrium by thin-layer chromatography. We rind that in both cell types, the most abundant metabolite is 3 beta-hydroxy-5 alpha-pregnan-20-one (70%), followed by 5 alpha-pregnane-3,20-dione (15%), and 3 alpha-hydroxy-5 alpha-pregnan-20-one (10%). A small amount is metabolized to 5 alpha-pregnane-3 alpha/3 beta,20 alpha-diols and to 3 beta,6 alpha-dihydroxy-5 alpha-pregnan-20-one. The metabolism of progesterone in cultured endometrial cells occurs rapidly; 70% of progesterone is metabolised in 8 h, and 90% by 24 h. We conclude that when in vitro experiments are conducted utilizing progesterone treatment, the rapidity and the extent of the metabolism of this steroid should be taken into account. (C) 1999 Elsevier Science Inc. All rights reserved.