Binding of estradiol and 5α-androstane-3β-17β-diol by the male rat enriched gonadotrop cells

Abstract

Dispersed pituitary cells from 42-day old male rats were separated using centrifugal elutriation. Based on LH and PRL cellular contents, fractionated cells were pooled into two fractions: “Lactotrop population” and “gonadotrop population”. Estradiol and 5α-androstane-3β,17β-diol binding was measured in these fractions. Results revealed that: (1) The steroid receptors are not destroyed by cell dispersion and elutriation. (2) The estradiol receptor content is higher in gonadotrop cells than in lactotrop cells. (3) The number of binding sites for the two steroids changes in the different fractions: whereas it is exactly similar in “lactotrop population”, it is much higher for estradiol than for 5α-androstane- 3β,17β-diol in “gonadotrop population”. These results suggest two different species—or conformations—of receptor binding sites for estradiol in the male rat pituitary; the first one could link both steroids, the second one would be specific for estradiol.