Expression of the Oxytocin and V1a Vasopressin Receptors in Human Myometrium in Differing Physiologic States and following Misoprostol Administration

Abstract

Objective: To assess relative expression levels of mRNA for the oxytocin receptor (OTR) and the V1a vasopressin receptor (V1aR) in human myometrium in various physiologic states and to determine if misoprostol exposure affects the expression of mRNA for these receptors. Study Design: Using semiquantitative reverse transcription-polymerase chain reaction, we analyzed myometrial samples from 37 women (10 menopausal, 10 nongravid premenopausal, 10 gravidae, 7 premenopausal misoprostol-treated nongravid women) for the specific expression of mRNA messages for OTR and V1aR. The presence of the OTR and V1aR protein was confirmed by immunohistochemistry. Results: We found that the expression of OTR was significantly higher in gravid compared to premenopausal nongravid (p < 0.0001), misoprostol-treated (p < 0.001) and menopausal myometrium (p < 0.0001). Differences in V1aR expression were not statistically significant among the four study groups. Conclusion: The expression of OTR mRNA in myometrium is markedly increased during late gestation. V1aR expression is present in all physiologic states, and does not appear to be altered by the presence or absence of labor. Misoprostol administration does not appear to have an effect on OTR and V1aR mRNA receptor expression.