Changes in the metabolic pattern of estrogens as a function of age in cultured myometrial cells: Synthesis of a lipoidal derivative of estradiol

The effect of ageing on estradiol (E 2 ) metabolism has been studied systematically in cultured ovine myometrial cells from the 2nd to the 25th subculture. Cell monolayers were incubated for various amounts of time with [ 3 H]E 2, and metabolites isolated from cells or medium by thin-layer chromatography (TLC). The main metabolites identified were estrone (E 1 ), estriol (E 3 ), 16- epi -E 3 and a lipoidal derivative of E 2 (LE 2 ). The latter had an R f of 0.90 and was recognized by its comigration with fatty acid on TLC and the release of E 2 after alkaline hydrolosis. In contrast to the other metabolites, LE 2 was found only in cells and was never secreted in the medium. In “young” cells (2nd subculture) the main metabolite was E 1 which represented 16.3% of the total radioactivity after 2 h of incubation and 33% after 8 h both in cells and medium. LE 2 appeared very slowly and represented only 13% after 8 h of incubation. In contrast in “old” cells (i.e. 10th subculture) LE 2 had become the most abundant metabolite representing as much as 25% of the total cellular radioactivity. This change from one metabolic pattern to the other was progressive and associated with a decrease in 17β-hydroxysteroid dehydrogenase (SDH) activity. LE 2 became prevalent relative to E 1 around the 5th subculture.