Objective: To quantify messenger RNA (mRNA) levels of the two estrogen receptor isoforms, estrogen receptor-alpha (ER-alpha) and estrogen receptor-beta (ER-beta) in the eutopic endometrium and ovarian endometriotic cysts.
Design: Prospective study.
Setting: University hospital.
Patient(s): Patients with endometriosis and patients with uterine leiomyoma or carcinoma in situ.
Intervention(s): Gonadotropin-releasing hormone agonist (GnRH-a)-treated (n = 12) or untreated (n = 24) endometriotic cysts were obtained from 36 patients during laparoscopic cystectomy. Eutopic endometrium tissues were obtained from 24 patients during or immediately after surgery.
Main outcome measure(s): ER-alpha and ER-beta mRNA levels, using a real-time reverse transcription (RT)-polymerase chain reaction (PCR) assay, TaqMan RT-PCR.
Result(s): Eutopic endometrium and ovarian endometriotic cysts showed predominantly higher levels of ER-alpha mRNA than ER-beta mRNA. Although ER-alpha and ER-beta mRNA levels in the eutopic endometrium were affected by a cyclic change in ovarian hormones, ovarian endometriotic cysts were less affected. Moreover, a long-term hypoestrogenic state induced by GnRH-a especially decreased ER-alpha mRNA levels in endometriotic cysts. Consequently, the relative ratios of ER-alpha to ER-beta mRNA levels in both GnRH-a-treated and untreated endometriotic cysts were significantly lower than those in the eutopic endometrium.
Conclusion(s): The results suggest that the principal and regulatory effects of estrogens may be mediated mainly via ER-alpha rather than ER-beta in both the eutopic endometrium and endometriotic cysts.