Objective: To investigate the messenger ribonucleic acid (mRNA) expression of interleukin-1 (IL-1) type I receptor in the endometrial tissue of normal patients during the menstrual cycle.
Design: Prospective longitudinal study.
Setting: Department of Obstetrics and Gynecology, Stanford University Medical Center, Stanford, California.
Patients: Twenty fertile women between 19 and 41 years of age underwent hysterectomy for benign reasons (n = 9) and laparoscopy for tubal ligation (n = 11). In all cases, endometriosis was not visualized.
Interventions: Endometrial biopsy using the Novak curette was obtained at the time of surgery.
Main outcome measure: Total RNA extracted from unfractioned endometrial tissue was analyzed on Northern blots by using specific complementary deoxyribonucleic acid probes.
Results: We found IL-1 type I receptor mRNA expression in endometrial tissue throughout the entire menstrual cycle. However, IL-1 type I receptor mRNA levels were significantly higher during both early and late luteal phases than follicular and midluteal phases.
Conclusions: Our results demonstrate the presence of the IL-1 system in the human endometrium and that the receptor is regulated throughout the menstrual cycle with a 4.1-fold increased expression of the IL-1 receptor gene in the early luteal phase compared with preovulatory endometrium.