Cycle variation and distribution in the concentration of cytosol estrogen and progesterone receptors in the normal human uterus and myoma.

The concentrations of cytosol estrogen receptor (ERc) and cytosol progesterone receptor (PRc) in the human endometrium, myometrium, fallopian tube, cervix, and myoma obtained from 20 patients have been measured by the dextran-coated charcoal method using estradiol-17 beta and R5020. The concentration of ERc of the endometrium and fallopian tube were significantly higher in the first half of proliferative phase compared to the other periods of the cycle (P less than 0.02). Significantly higher concentrations of PRc of the endometrium, myometrium and fallopian tube were obtained in the second half of proliferative phase (P less than 0.01). The ERc of the myometrium and the cervix, and the PRc of the cervix did not show any significant difference in the concentration during the proliferative phase, but mean values of the proliferative phase were higher than those of the secretory phase (P less than 0.05). Similar cyclic variations of ERc and PRc throughout the menstrual cycle was observed in small myoma, less than 3 cm in diameter. The concentration of ERc of small myoma in the first half of proliferative phase was three times higher than that of normal myometrium (P less than 0.01), but there was no significant difference in the concentration of PRc. Dissociation constants of ERc and PRc in all the tissue examined were in the range of 10(-10) and 10(-9) M, respectively, and did not fluctuate throughout the menstrual cycle. Results suggest that the endometrium, myometrium and fallopian tube are in a group and the cervix is different from them in terms of the pattern of variation in the concentration of ERc and PRc and the ratio of PRc to ERc (PRc/ERc) throughout the menstrual cycle. It is noteworthy that the PRc/ERc of small myoma was lower than normal myometrium, suggesting the possible relation to the pathological growth of myoma.