Glucocorticoid receptors and glucocorticoid effects in rat Sertoli cells

In this report we demonstrate glucocorticoid receptors in seminiferous tubules of the rat testis, and that these receptors are localized in Sertoli cells and peritubular cells. The receptors had high affinity for [3H]dexamethasone (Kd = 0.5 - 1 x 10(-9) M), and similar Kd values were calculated from equilibrium analysis and from rate studies (k1 = 1.5 x 10(6) M-1 min-1 and k-1 = 1.4 x 10(-3) min-1, O C). Binding specificity was typical for glucocorticoid receptors (affinity: dexamethasone greater than corticosterone greater than cortisol approximately R5020 approximately progesterone greater than aldosterone = R1881 greater than 17 beta-estradiol approximately cortisone approximately testosterone greater than 5 alpha-dihydrotestosterone). The concentration of glucocorticoid receptors in rat seminiferous tubules revealed an age-dependent decrease, coinciding with the increase in the number of germ cells. Glucocorticoid receptor levels were higher in Sertoli cells from immature rats than in cells from adult rats. Cultured peritubular cells from immature rats contained levels of glucocorticoid receptors similar to cultured Sertoli cells from rats of the same age. With a nick-translated human glucocorticoid receptor complementary DNA probe, a messenger RNA (mRNA) species of approximately 7 kilobase was clearly detected in both Sertoli cells and peritubular cells. In peritubular cells, a smaller mRNA species (5 kilobase) was also clearly detectable. In mRNA from whole testis tissue, a similar developmental pattern as for dexamethasone binding was found. Dexamethasone caused a concentration-dependent stimulation of mRNA levels for androgen binding protein and for the cAMP-dependent protein kinase regulatory subunit type II beta in cultured immature rat Sertoli cells. On the other hand, mRNA levels for glucocorticoid receptor decreased, whereas mRNA levels for beta-actin remained constant. This report documents for the first time the presence of glucocorticoid receptors and glucocorticoid effects in rat Sertoli cells, and is also the first demonstration of glucocorticoid receptors in peritubular cells of the rat testis.