PROSTAGLANDIN PRODUCTION DURING SPONTANEOUS LABOR AND AFTER TREATMENTWITH RU486 IN PREGNANT RHESUS MACAQUES

The production of prostaglandins from amnion, chorion, decidua, and my ometrium was studied in a superfusion system to determine the level of prostaglandin production during late pregnancy, during spontaneous la bor, and after in vivo treatment with RU486. Tissues were divided into three groups: those from pregnant control animals, those from animals receiving RU486 (20 mg/kg/day for 3 days) in vivo, and those from ani mals in spontaneous term labor. Tissues were collected at cesarean sec tion and placed in the superfusion system. After a 30-min equilibratio n period, fractions of media were collected after passing through the tissue chambers and were assayed for prostaglandin F-2 alpha (PGF(2 al pha)) and prostaglandin E(2) (PGE(2)). The results showed a significan t increase in PGF(2 alpha) from decidua of animals treated with RU486 compared to pregnant controls (pregnant: 3.01 +/- 0.45 ng/g/min; RU486 : 4.45 +/- 0.28 ng/g/min; p < 0.05). There was a dramatic increase in PGE, production by amnion from animals in spontaneous labor but not af ter RU486 treatment (pregnant: 0.21 +/- 0.06 ng/g/min; RU486: 0.56 +/- 0.09 ng/g/min; spontaneous labor: 5.83 +/- 0.43 ng/g/min; P < 0.01). We conclude that while progesterone is important for maintaining uteri ne quiescence during pregnancy, progesterone receptor blockade by RU48 6 does not lead to an increase in PGE(2) production by amnion as is sh own during normal spontaneous labor.