Regulation of human oxytocin receptor (OTR) in primary human amnion cells

Abstract

Oxytocin-stimulated PGE₂ release is enhanced by the up-regulation of oxytocin receptors at the end of pregnancy. We have shown previously that OTR is upregulated by IL-1β and synergistically upregulated by C/EBPβ and NF-κB transcription factors in human myocytes. The present work was directed toward understanding the regulation of OTR in human amnion at term. OTR mRNA before and after labour was measured using real-time RT-PCR. The expression of OTR in labour (+) primary amnion cells is 16-fold higher than in labour (−) amnion cells (P < 0.001). Treatment with IL-1β resulted in a significant upregulation of OTR which peaked with a 17-fold induction after 6 hours (P < 0.001). IL-1β caused a 16-fold increase in OTR mRNA levels in labour (–) cells, bringing the expression level up to that found in labour (+) cells. Amnion cells were transfected with an OTR promoter reporter vector. Promoter activity was increased fivefold by co-transfection with C/EBPβ or NF-κB p65 (P < 0.05). Co-transfection of C/EBPβ and NF-κB p65 together increased OTR promoter activity 50-fold (P < 0.05).