Increased prostacyclin synthesis by atherosclerotic arteries from estrogen-treated monkeys

We hypothesized that the atheroinhibitory and cardioprotective effects of e strogen may be mediated in part through increased prostacyclin formation by the artery wall. Atherosclerotic abdominal aorta was collected at necropsy from ovariectomized female monkeys fed an atherogenic diet alone or with a dded Premarin(R). Basal and arachidonate-stimulated prostacyclin and thromb oxane synthesis by artery segments was measured by radioimmunoassay. In con trast to no observed differences in basal release of prostacyclin by the co ntrol and estrogen-treated arteries, there was a marked increase (similar t o 165%) in arachidonate-stimulated formation of prostacyclin by estrogen-tr eated arteries, and pros tacyclin synthesis was inversely correlated with p laque size. No differences were observed in basal or arachidonate-stimulate d thromboxane synthesis by the control and estrogen-treated arteries. In li ght of known antiatherogenic and vasodilatory effects of estrogen, increase d prostacyclin synthesis by estrogen-treated arteries may, in part, explain estrogen's beneficial effects on the artery wall. (C) 2001 Elsevier Scienc e Inc. All rights reserved.