Estradiol Inhibits Arachidonic Acid Metabolism in Renal and Vascular Tissue

Abstract

The present study was designed to determine the effect of estrogen on the synthesis of eicosanoids. After ovarectomizing rats, 17β estradiol (25 μg/kg) was administered by s.c. injection. In control and treated animals, conversion of [1-¹⁴C] arachidonic acid was done in blood vessels, kidney cortex and medulla. The radiolabeled products were separated by high-performance liquid chromatography. After 17β estradiol treatment, significant reductions of 78% and 48% were seen in both cyclo- oxygenase and lipoxygenase products in blood vessels and kidney medulla, respectively. Further analysis showed no significant difference in the percent inhibition by 17β estradiol among the various eicosanoids. No significant effect by 17β estradiol was seen in the cortex. However, polar, unidentified, radioactive compounds were the major products in this tissue as well as being present in the blood vessels and medulla. The evidence suggests that 17β estradiol inhibition of eicosanoids, by increasing the acylation of arachidonic acid into tissue phospholipids, may be contributing to the development of hypertension and thromboembolism seen with this hormonal treatment.

Key Words:

• Estradiol
• Eicosanoids
• Blood vessels
• Kidney