The relative abundance of type 1 to type 2 cyclo-oxygenase mRNA in human amnion at term

The onset of labor in humans is associated with an increase in prostaglandin production. One of the key steps is the conversion of arachidonic acid to prostaglandin E2 by cyclo-oxygenase (Cox). Cox has been found to exist as two distinct genes, Cox-1 and Cox-2. We have used RT-PCR to study the relative abundance of mRNA from each Cox gene in amnion at term. Quantitation of PCR efficiency indicated an approximate 100 fold excess of Cox-2 messenger RNA over that for Cox-1. These data point to the importance of Cox-2 in the increased prostaglandin synthesis associated with labor. Further studies should therefore focus on the control mechanisms for Cox-2.