Correlation of the Levels of Oxytocin Receptor and the Enzymes for Prostaglandin Synthesis to NF-�eB Activation in Human Pregnant Myometrium at Term

Abstract

The switch from pregnancy to delivery involves various changes in expression of uterine activation proteins (UAPs). Increasing body of evidence indicates that human labor is an inflammatory event which results in the activation of nuclear factor kappa B (NF-κB) in uterus. Our aim was to analyze the correlation between the level of activated NF-κB and the expression of UAPs including oxytocin receptor (OTR), cyclooxygenase-2 (COX-2), microsomal prostaglandin E synthase-1 (mPGES-1), and prostaglandin F synthase (PGFS) in pregnant human myometrium at term. The myometrial tissues were obtained from pregnant women who were in labor (TL) or not in labor (TNL) at term. Western blotting was used to determine the level of activated NF-κB and the expression of OTR, COX-2, mPGES-1 and PGFS in pregnant myometrium. The expression of OTR, COX-2, mPGES-1 and PGFS was significantly up-regulated in TL group compared with TNL group (P ＜ 0.01). The level of activated NF-κB was significantly higher in TL tissues than that in TNL biopsies (P ＜ 0.01). Significant positive correlations were found between the level of activated NF-κB and the expression of OTR (P＜0.05), COX-2 (P＜0.05), mPGES-1 (P＜0.01) or PGFS (P＜0.01). Upregulation of UAPs such as OTR, COX-2, mPGES and PGFS is correlated to the activation of NF-κB in pregnant human myometrium at term. Our data support the hypothesis that inflammation leads to uterus activation for labor.