Formation of Estrogen Glucuronides by Human Granulosa-Luteal Cells Isolated from Human Menopausal Gonadotropin-Stimulated Cycles for in Vitro Fertilization

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Abstract
The formation of steroid glucuronides by human granulosa cells isolated from human menopausal gonadotropin (hMG)/human chorionic gonadotropin (hCG)-stimulated cycyles for in vitro fertilization was studied. From granulosa cells in suspension, 5 .times. 10-7 M androstenedione was converted into estradiol (2.50 .+-. 0.21 ng/ml), estrone (1.84 .+-. 0.16 ng/ml), estradiol glucuronide (0.38 .+-. 0.07 ng/ml), as well as estrone glucuronide (0.24 .+-. 0.04 ng/ml). When 5 .times. 10-7 M estradiol was incubated, estrone (15.5 .+-. 0.9 ng/ml) and estradiol glucuronide (0.12 .+-. 0.05 ng/ml) were detected in medium. Using the same preparation of granulosa cells, we have observed that androsterone could uniquely be transformed into androstane-3.alpha.,17.beta.-diol (1.42 .+-. 0.56 ng/ml), and only low amounts of steroid glucuronides could be detected. Since the formation of steroid glucuronides was extremely small when granulosa cells in suspension were used, we subsequently studied granulosa cells in culture. When 5 .times. 10-7 M estradiol was added, estrone (7.8 .+-. 1.3 ng/ml) and estradiol glucuronide (0.68 .+-. 0.08 ng/ml) were formed. The addition of follicle-stimulating hormone did not cause a further increase in estrone or estradiol glucuronide levels. As observed with granulosa cells in suspension, incubation with androsterone led to the formation of androstane-3.alpha.,17.beta.-diol (24.2 .+-. 0.07 ng/ml). Our data demonstrated the presence of glucuonyltransferase in human granulosa cells obtained from preovulatory follicles of hMG/hCG-treated women. In addition, since the conversion of androsterone into C-19 steroid glucoronide was relatively small, the present finding also indicates that the glucuronyltransferase enzymatic activity in granulosa-luteal cells preferentially conjugated estrogens.