THE EFFECT OF AROMATASE INHIBITOR ON BASAL AND TESTOSTERONE-SUPPLEMENTED ESTRADIOL SECRETION BY LEYDIG-CELLS IN-VITRO

The effect of increasing concentrations of aromatase inhibitor CGS 169 49 A on LH- and testosterone-supplemented estradiol secretion by Leydi g cells was studied. Leydig cells were obtained from mice at different ages from 15- to 140-day-old. They were either incubated for 6 hrs wi th LH and/or testosterone (LH/testosterone-supplemented cultures), or as the control cultures. Aromatase inhibitor was added for further 18h . After 24-h incubation period estradiol secretion was radioimmunologi cally examined. Leydig cell aromatase activity appeared to depend on t he age of the donor mice, being higher in mature than in juvenile anim als. Furthermore, the Leydig cells from 30-day-old mice seemed to reve al such an increasing aromatase activity resulting in the higher level of synthetized estradiol. Aromatase inhibitor influenced the Leydig c ell functions in a dose-dependent manner (60-70-day-old mice), or inde pendently of the dose used. This supports the hypothesis that Leydig c ells from the testes of mature mice are the main site of an active aro matase.