Expression of cyclo-oxygenase types-1 and-2 in human myometrium throughoutpregnancy

Human labour is associated with increased prostaglandin synthesis within th e uterus. The aim of this study was to examine the expression of the two is oforms of the central prostaglandin synthetic enzyme, cyclooxygenase (COX-1 and COX-2) in human myometrium throughout pregnancy and to test the hypoth esis that COX in the myometrium may play a role in labour onset. Expression of COX-1 and COX-2 at the mRNA level was analysed using reverse transcript ase-polymerase chain reaction (RT-PCR) and at the protein level using Weste rn blotting. No significant changes of COX-1 RNA or protein expression were observed either with gestational age or labour. COX-2 mRNA and protein exp ression increased at term with significant upregulation occurring prior to the onset of labour (P < 0.005). These data would suggest that up-regulatio n of COX-2, rather than COX-1, mediates increased prostaglandin synthesis i n human myometrium at term. The increased COX-2 expression observed precede d labour onset, suggesting that COX-2 has a role in labour onset, rather th an its presence merely a consequence of labour.