Some Effects of Prostaglandins E2 and F2α on the Pregnant Rhesus Monkey1

Abstract

Prostaglandin E₂(PGE₂) or prostaglandin F_2α (PGF_2α) was injected subcutaneously or infused intravenously into pregnant rhesus monkeys. Animals were between day 30 and 127 of pregnancy; pregnancy termination, serum progestin levels, and uterine contractility were parameters measured to determine efficacy. Subcutaneous injections of PGF_2α or PGE₂ terminated pregnancy in 8 of 13 animals when given between day 30 and 41 and beyond day 100 of pregnancy. Intravenous infusion terminated 3 of 7 animals between day 30 and 40 of pregnancy. Progestin levels were usually depressed within 24–48 hr after the initial administration of prostaglandin, whereas uterine contractility was increased within 20–30 min. Prostaglandin E₂ was about 10 times as potent as PGF_2α in causing uterine contractions; intravenous infusion of 0.8 and 8.0 μg/min, respectively, caused maximal uterine contractions during the latter half of pregnancy. The realtionship of these compounds to normal pregnant uterine physiology in the human and rhesus monkey is discussed.