Oxytocin receptor gene expression of estrogen-stimulated human myometrium in extracorporeally perfused non-pregnant uteri

Oxytocin (OT) and the oxytocin receptor (OTR) seem to be less important for uterine contractility-associated disorders of the non-pregnant uterus compared to the pregnant uterus. In the present study, we investigated the mutual dependence of OTR, OT and 17beta-estradiol (E-2) with regard to the localization of OTR in the non-pregnant uterus. Utilizing our established model for extracorporeal perfusion of the human uterus, we perfused 15 human uteri for 27 h under physiological conditions without oestradiol (group A, n = 5) or with high E-2 Stimulation (group B, n = 5) followed by OT stimulation for both groups during the last 3 h of the experiment. Negative controls (n = 5) remained in perfusions for 27 h without any further hormone treatment. Gene expression of the myometrial OTR in both groups was compared using reverse transcriptase triple primer PCR. Stimulation with E-2 and OT led to significantly higher OTR gene expression than stimulation with OT alone. We also showed that concentrations of OTR transcripts increase from the lower uterine segment to the uterine fundus. However, maximum OTR levels of the uterine fundus in group B did not reach concentrations of specimens of third trimester of pregnancy which were used as positive controls. We conclude that our experimental model simulates a situation similiarly to the stimulated nonpregnant uterus in the therapeutic concepts of assisted reproduction. The data presented demonstrate that the dynamics of OTR expression can be modulated by stimulation with E-2 and OT, not only in the pregnant but also in the non-pregnant uterus.