Estrogen and Androgen Receptors in Sertoli, Leydig, Myoid, and Epithelial Cells: Effects of Time in Culture and Cell Density*

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Abstract
Estrogen and androgen receptors were measured in the cytosol prepared from established cell lines of Sertoli, Leydig, myoid, and endothelial cells, as well as in primary Sertoli cell-enriched cultures. Estradiol-binding sites with characteristics of estrogen receptors were identified in established lines of Sertoli cells from rat [43 .+-. 7 (mean .+-. standard error of the mean) fmol/mg protein; Kd = 1.1 nM] and mouse (34 .+-. 4 fmol/mg protein; Kd = 0.9 nM). The binding sites were estrogen specific, since only estradiol and diethylstilbestrol, but not testosterone, progesterone, or dexamethasone, competed with [3H]estradiol for binding sites in the cytosol prepared from the cell lines. Exposure of the cells to estradiol (10 nM) resulted in accumulation of estrogen receptors in nuclei, with maximal uptake by 30 min. The estrogen receptor concentration was very low or undetectable (< 10 fmol/mg protein) in primary cultures of rat Sertoli cells that were cultured for 3 days. However, after 15 days in culture, the estrogen receptor concentration increased and reached levels similar to those in the established Sertoli cell lines. No estrogen receptors were measurable in myoid or endothelial cells. By contrast, androgen receptors were identified in all 5 cell lines and in primary Sertoli cells cultured for 3 and 15 days. The content of both estrogen and androgen receptors in the mouse Sertoli cell line increased as a function of cell density. Androgen receptors are present in all of the testicular somatic cell lines examined, and in primary Sertoli cells. Estrogen receptors are present in Sertoli cell and Leydig cell lines, but not in myoid and endothelial cell lines. The low estrogen receptor concentration in Sertoli cells cultured for 3 days increases 4-fold after 15 days in culture. Cell density is a major regulator of the concentrations of estrogen and androgen receptors in the Sertoli cell line.