TOTAL AND UNBOUND CYTOSOLIC ESTROGEN AND PROGESTERONE RECEPTORS IN MYOMETRIUM AND FIBROID AFTER GONADOTROPIN-RELEASING-HORMONE AGONIST TREATMENT

Objective: To study the changes in bound and unbound cytosolic estroge n receptor (ER) and progesterone receptor (PR) in fibroid and myometri um after treatment with gonadotropin-releasing hormone agonists (GnRH- a). Design: Prospective randomized study. Setting: A tertiary institut ional hospital. Patients: Thirty premenopausal women with normal regul ar menstrual cycles and uterine fibroids. Interventions: Patients were randomized to receive buserelin acetate for 3 months (n = 20) or no t reatment (n = 10) before hysterectomy. Main Outcome Measures: Bound an d unbound ER and PR. Results: In nontreated women, values of unbound E R and PR in fibroid were higher than in myometrium. There were no diff erences in total receptors. The total and unbound ER in myometrium was higher in treated than in nontreated women. There were no differences in fibroid. Conclusions: The higher content of unbound hormone recept ors in fibroid correlates with an exacerbation of the hormone dependen ce of this tissue compared with myometrium. The increase of total and unbound ER in myometrium after treatment suggests a higher level of sy nthesis or a lower level of degradation of receptors in this tissue.