Induction of a decrease in renal NAD⁺-dependent 15-hydroxyprostaglandin dehydrogenase activity by estradiol in rats

The effect of estradiol administration on renal and pulmonary NAD⁺-dependent 15-hydroxyprostaglandin dehydrogenase activities in rats was studied. Estradiol induced a significant decrease in renal but not in pulmonary enzyme activity. Kinetic parameters for the renal enzyme from control and treated groups were compared. An identical apparent K_m for prostaglandin E₂ was obtained for the enzyme from both groups. V_max in the treated group was progressively decreased and plateaued 1 day after estradiol injection. The estradiol-induced decrease in renal enzyme activity was blocked by an anti-estrogen, nafoxidine, suggesting that the effect of estradiol was a receptor-mediated event. The decrease in renal prostaglandin catabolic enzyme activity induced by estradiol may result in prolonging the half-life of circulating prostacyclin and may account, in part, for the anti-thrombogenic effect of estradiol.