Oxytocin and vasopressin 1a receptor gene expression in the cycling or pregnant human uterus

OBJECTIVE: Our purpose was to compare concentrations of messenger ribonucle ic acid specific for the oxytocin receptor and for the vasopressin la recep tor in myometrial and endometrial tissues of pregnant and nonpregnant women . STUDY DESIGN: Tissues from pregnant uteri were obtained from 95 women who w ere undergoing cesarean delivery between 26 and 42 weeks' gestation. Tissue s from nonpregnant uteri were obtained from 7 cycling women who were underg oing hysterectomy. The competitive reverse-transcription polymerase chain r eaction method was used to determine messenger ribonucleic acid concentrati ons. RESULTS: A significant increase in oxytocin receptor messenger ribonucleic acid was found during the first half of pregnancy. Oxytocin receptor messen ger ribonucleic acid concentrations were lower in tissues with spontaneous contractions than in quiescent tissues and were decreased in patients with advanced labor. Vasopressin la receptor messenger ribonucleic acid concentr ations were high in tissues from both cycling and pregnant uteri but remain ed unchanged throughout gestation. CONCLUSION: The increase in oxytocin receptor protein concentrations seen i n pregnancy is only partially controlled by messenger ribonucleic acid abun dance. High concentrations of vasopressin la receptor messenger ribonucleic acid confirm the biologically active role of this receptor in both the cyc ling and the pregnant uterus.