PREGNANCY AND LIPID PEROXIDE-INDUCED ALTERATIONS OF EICOSANOID-METABOLIZING ENZYMES IN THE AORTA OF THE RAT

OBJECTIVES: We examined whether pregnancy modulates the expression of prostaglandin endoperoxide synthase, prostacyclin synthase, and thromb oxane A2 synthase in the systemic vasculature. Further, we examined wh ether elevated lipid peroxidation during pregnancy (induced by vitamin E deprivation) affects the normal adaptive process to pregnancy. STUD Y DESIGN: Western immunoblotting was performed on aortas from normal a nd vitamin E-deprived late pregnant (18 to 19 days) and age-matched vi rgin control rats. RESULTS: Normal pregnancy resulted in an increased expression of prostaglandin endoperoxide synthase (2.91 vs 1.06 fmol/n g deoxyribonucleic acid, p < 0.05). Surprisingly, the expression for b oth prostacyclin and thromboxane A2 synthases were significantly decre ased by pregnancy: prostacyclin synthase 2.60 versus 13.82 units/ng de oxyribonucleic acid and thromboxane A2 synthase 1.32 versus 9.85 units /ng of deoxyribonucleic acid. Elevation of endogenous lipid peroxidati on partially reversed this normal pregnancy trend in enzyme expression : prostaglandin endoperoxide synthase 1.85 fmol/ng deoxyribonucleic ac id, prostacyclin synthase 9.38 units/ng deoxyribonucleic acid, thrombo xane A2 synthase 4.36 units/ng deoxyribonucleic acid. CONCLUSION: Chan ges in prostanoid activity in the systemic vasculature during pregnanc y may be mediated by concerted induction and down-regulation of specif ic enzymes. Increased lipid peroxidation interferes with this normal p regnant pattern. Further studies on the cell-specific expression of th ese genes will help to define the cardiovascular role of prostaglandin s in pregnancy and in preeclampsia.