Characterization and assay of the nuclear and cytosolic progesterone (P) receptors in Premarin -primed human endometrium and myometrium after single-dose P administration

Abstract

Progesterone receptors (RP) were characterized and measured in the 0.4 M KCl nuclear extract and in the cytosol of 7 to 11 days Premarin (Premarin, Ayerst Laboratories, New York, NY) primed human endometrium and myometrium with [3H]R5020 as the ligand. The test group comprised 12 women who received progesterone injection 1 to 3 hours before tissue collection; the control group numbered 10 women. Receptor characteristics in both the endometrium and the myometrium, in the nuclear extract and cytosol in the test group and in the cytosol in the control group, were similar and were demonstrated by (1) high specificity, (2) sedimentation constant of 4.7 to 6.5S in the cytosols and 2.8 to 3.9S in the nuclear extract, (3) saturable affinity with Kd of 2.2 to 3.5 nM and 1.9 to 3.3 nM, respectively. Total RP levels (nuclear extract and cytosol) ranged from 1030 to 13,270 and 1280 to 17,300 fmol/mg DNA, respectively, in the endometria of women in the test and control groups. In 13 of 14 women myometrial total RP levels were higher than in the endometrium. There was a significant difference in the distribution of the RP between the test and the control groups: 50% and 48% of the receptor were measured in the nuclear extract in the endometrium and myometrium, respectively, in the test group, compared with 25% and 21% in the control group (P less than 0.001).