Effects of PGF 2α and PGF 2α, 1–15 lactone on the corpus luteum and on early pregnancy in the rhesus monkey

Abstract

The effects of prostaglandin (PG)F 2α and PGF 2α, 1–15 lactone were compared in luteal phase, non-pregnant and in early pregnant rhesus monkeys. Animals treated with either PG after pretreatment with human chorionic gonadotropin (hCG) had peripheral plasma progesterone concentrations that were not statistically different from those in animals treated with hCG and vehicle. However, menstrual cycle lengths in monkeys treated with PGF 2α, 1–15 lactone were significantly (P <0.02) shorter than those in vehicle treated animals. In the absence of hCG pretreatment, plasma progesterone concentrations were significantly (P <0.008) lower by the second day after the initial treatment with either PGF 2α or PGF 2α, 1–15 lactone than in vehicle treated monkeys. Menstrual cycle lengths in monkeys treated with either PG were significantly (P <0.04) shorter than those in animals treated with vehicle. There were no changes in plasma progesterone concentrations in early pregnant monkeys treated with PGF 2α, and pregnancy was not interrupted. In contrast, plasma progesterone declined and pregnancy was terminated in 5 of 6 early pregnant monkeys treated with PGF 2α, 1–15 lactone. These data indicate that PGF 2α, 1–15 lactone decreases menstrual cycle lengths in non-pregnant rhesus monkeys. More importantly, PGF 2α, 1–15 lactone terminates early pregnancy in the monkey at a dose which is less than an ineffective dose of PGF 2α.