Evidence for an androgen receptor in porcine Leydig cells.

Cytosol and nuclear androgen receptor concentrations were measured in freshly prepared and cultured Leydig cells of immature pig testis with exchange assays using [3H]methyltrienolone as labelled ligand. Androgen receptors in Leydig cells had high affinity for [3H]methyltrienolone and steroid binding specificity typical of an androgen receptor. The mean receptor concentrations were 76 fmol/mg protein and 210 fmol/mg DNA for cytosol and nuclei, respectively. In sucrose gradients, cytosol androgen receptors sedimented in the 4 S region. The cells maintained androgen receptors under culture conditions. Exposure of cultured cells to [3H]methyltrienolone (10 nmol/l) resulted in accumulation of androgen receptors in the nuclei with maximal uptake by 1 h. We conclude that methyltrienolone binding sites with characteristics of androgen receptors were identified in both cytosol and nuclei of porcine Leydig cells.