Progesterone receptors in vaginal tissue of post-menopausal women

Progesterone receptors were measured in both cytosolic and nuclear fractions in vaginal tissue samples obtained from a total of 17 post-menopausal women. Ten of the women were given oestriol (E3) intravaginally 6-24 h before surgery, while the remaining 7 received no treatment. Cytosolic receptors were not detected in any of the 7 tissue samples from the untreated women, but nuclear receptors were present in two cases. In the 10 women treated with E3, it was possible to measure cytosolic receptors in 5 tissue samples and nuclear receptors in 7 samples. The mean receptor concentrations in the cytosolic and nuclear fractions were similar (45-65 fmol/mg protein) and the apparent dissociation constant of the receptors in all the samples was 1-2 nmol/1. These data would seem to indicate that oestrogen treatment results in the synthesis of new receptors, although not in all tissues, which compounds the scepticism regarding the validity of the classical two-step model for steroid hormone action.