Myometrial microvascular endothelial cells express oxytocin receptor

Objective 1. To establish whether microvascular endothelial cells from the human myometrium (MMECs) express oxytocin receptor, and to compare its expression levels relative to HUVECs. 2. To verify an upregulation of oxytocin receptor expression in MMECs as a result of vascular endothelial growth factor (VEGF), which had been found in a previous study. Design Laboratory scientific study. Setting University department. Population or Sample Myometrial biopsies from 12 hysterectomy specimens. Methods MMECs and HUVECs were established in vitro. Immunohistochemistry of in vitro cultures was performed to investigate protein expression of the oxytocin receptor. Semi-quantitative RT-PCR and Northern blots were performed to examine the presence and relative abundance of oxytocin receptor mRNA in MMECs and HUVECs, and in both cell types with and without VEGF. Total RNA from oxytocin acetate (100 nmol/L) and vehicle stimulated endothelial cell cultures was used to examine gene expression differences on a 10.5K cDNA microarray. Main outcome measures Oxytocin receptor mRNA and protein; gene expression analysis. Results Oxytocin receptor mRNA and protein was present in MMECs. The level of expression was the same as for the HUVECs, but much less than the pregnant myometrium. No effect on gene expression could be demonstrated by gene expression microarray following 10 hours of oxytocin stimulation. Twenty-four hours of VEGF stimulation did not significantly alter oxytocin receptor mRNA expression in MMECs or HUVECs. Conclusion The myometrial microvasculature expresses oxytocin receptor. This finding means that oxytocin may exert some of its effects on the myometrial microvasculature. No evidence could be found for a transcriptional effect of oxytocin stimulation in this study, but further work on the role of the myometrial vessel oxytocin receptor is needed.