Oxytocin receptors in bovine cervix during pregnancy and parturition: gene expression and cellular localization.

OBJECTIVES

Our purpose was to determine the expression of transcripts encoding the oxytocin receptor protein in bovine cervix during pregnancy and parturition, the cellular localization of immunoreactive oxytocin receptors, and oxytocin receptors concentrations in the same tissues.

STUDY DESIGN

Ribonuclease protection assay for oxytocin receptor messenger ribonucleic acid was used to determine gene expression in bovine cervical tissues obtained from 20 cows throughout pregnancy and parturition, cellular localization of oxytocin receptors was determined by immunohistochemistry, and tritiated oxytocin binding was measured in each tissue.

RESULTS

Oxytocin receptor gene expression and tritiated oxytocin binding were well correlated in each instance. During pregnancy the level of oxytocin receptor messenger ribonucleic acid was very low; it was increased at term with a further, marked increase at parturition. Tritiated oxytocin binding also increased dramatically at parturition and was most abundant in the mucosal layer. Strong oxytocin receptor immunoreactivity was present in mucosal epithelial cells, and scattered muscle cells in the muscular part showed the signal.

CONCLUSIONS

Our results, together with the previous finding that oxytocin stimulates prostaglandin E2 release from cervical tissue in vitro, indicate that cervical mucosal epithelial cells are targets for oxytocin at parturition and may mediate release of prostaglandin E2.