Oxytocin mRNA content in the endometrium of non-pregnant women

Objective To study oxytocin mRNA in the human endometrium at different phases of the menstrual cycle. Design An exploratory study in non-pregnant women. Setting The Department of Obstetrics and Gynecology, Lund University Hospital, Sweden. Participants Thirty-three women of fertile age undergoing hysterectomy or endometrial curettage on routine benign gynaecologic indications. Methods Endometrial tissue was obtained throughout the menstrual cycle. The presence of oxytocin mRNA was investigated by in situ hybridisation and by real time PCR. Main outcome measures Oxytocin mRNA signalling intensity found by in situ hybridisation of tissue obtained at different times of the menstrual cycle. Relative amounts of oxytocin mRNA measured by real time PCR. Results The signal for oxytocin mRNA obtained by in situ hybridisation was more pronounced in glandular epithelial cells than in stromal cells. Furthermore, it was most marked around mid-cycle. The expression of oxytocin mRNA was confirmed by real time PCR. Conclusions The results indicate that oxytocin may be synthesised in the endometrium of non-pregnant women, particularly in the glandular epithelial cells. Hormone released from these sources may have a paracrine action on the uterus. Oxytocin mRNA expression seems to be ovarian hormone dependent with the highest concentration around mid-cycle.