Objective: To investigate the activities of the 2 isoforms of prostaglandin synthetic enzyme cyclo-oxygenase (COX), COX-1 and COX-2, in the placental tissue of women with pre-eclampsia and healthy pregnant women. The relationship between placental lipid peroxidation and the activities of COX-1 and COX-2 was also investigated.
Methods: Tissue specimens were obtained from pre-eclamptic women (20 had severe pre-eclampsia and 38 had mild pre-eclampsia) and 27 healthy pregnant women who underwent cesarean section before the onset of labor. Malondialdehyde (MDA) levels and COX-1 and COX-2 activities were measured in placental tissue homogenates.
Results: Mean activities for COX-1 and COX-2 were significantly lower in women with severe pre-eclampsia than in healthy controls (P<0.05 and P<0.01, respectively). COX-1 and COX-2 activities were also lower in women with mild pre-eclampsia than in healthy controls, but the difference was of borderline significance (P=0.049 and P=0.059, respectively). The mean placental MDA level was significantly higher in pregnant women with severe and mild pre-eclampsia than in healthy pregnant women (P<0.01 for both). The correlation analysis showed significant negative correlations between MDA and COX-1 (r=-0.44, P<0.001) and MDA and COX-2 (r=-0.45, P<0.001) in the placental tissue of women with pre-eclampsia.
Conclusion: These results suggest that COX-1 and COX-2 activities are decreased in the placental tissue of women with pre-eclampsia, probably by oxidative stress.