Autocrine/Paracrine Action of Oxytocin in Pig Endometrium1

Luminal epithelial cells of porcine endometrium are unresponsive to oxytocin (OT) in vitro although they express the greatest quantity of OT and receptors for OT in vivo. Therefore, the objective of this study was to determine if oxytocin acted in an autocrine manner on luminal epithelial cells to stimulate prostaglandin (PG)F2α secretion. Treatment of endometrial explants or enriched luminal epithelial cells with OT antagonist L-366,948 decreased (P < 0.05) basal secretion of PGF2α. Oxytocin increased (P < 0.01) PGF2α secretion from luminal epithelial cells that were pretreated with 1:5000 or 1:500 OT antiserum for 3 h to immunoneutralize endogenously secreted OT. However, OT only increased (P < 0.05) PGF2α secretion from glandular epithelial cells when pretreated with 1:500 OT antiserum. Pretreatment with OT antiserum did not alter the ability of OT to induce PGF2α secretion from stromal cells. Medium conditioned by culture of luminal epithelial cells stimulated (P < 0.05) phospholipase C activ...