title: Effects of (15S)-15-methyl prostaglandin E2 alpha methyl ester and estrogens upon the corpus luteum and conceptus of the rhesus monkey.
abstract: The corpus luteum inhibiting activity of (15S)-15-methyl prostaglandin F2 alpha methyl ester (15M-PGF2 alpha) was determined when given in combination with estrogens. Administration of 15M-PGF2 alpha alone (3 injections of 500 microgram each) to monkeys concomitantly receiving hCG reduced serum progesterone concentrations to 50% of values observed in control animals. Ethinyl estradiol or mestranol alone did not inhibit the corpus luteum of the hCG-treated, nonpregnant monkey. Serum progesterone values for nonpregnant monkeys treated with 15M-PGF2 alpha plus estradiol-17 beta, ethinyl estradiol or mestranol did not differ statistically from those observed in monkeys treated with 15M-PGF2 alpha alone. The dose of 15M-PGF2 alpha (3 x 500 microgram) which only partially inhibited the corpus luteum of the hCG-treated, nonpregnant monkey promptly terminated gestation when given on Day 28 od fertile menstrual cycles. Pregnancy terminated in two of three treated monkeys when the dose of 15M-PGF2 alpha was reduced ten-fold (3 x 50 microgram). Mestranol alone reduced serum progesterone and estradiol-17 beta concentrations to one-half and one-third of pretreatment values, but did not interrupt pregnancy. Pregnancy terminated in only two of five monkeys when mestranol was administered with the low dose of 15M-PGF2 alpha. It is concluded that: 1) estrogens do not enhance the corpus luteum inhibiting of 15M-PGF2 alpha in the nonpregnant monkey; 2) the primary action of 15M-PGF2 alpha during early pregnancy is upon the conceptus and not the corpus luteum; 3) concomitant treatment with mestranol and 15M-PGF2 alpha offers no advantage of 15M-PGF2 alpha alone for the termination of early pregnancy; and 4) mestranol alone can impair the steroidogenic potential of the corpus luteum of early pregnancy, but is not sufficiently active to terminate gestation.
mesh_terms: D000818:Animals; D002260:Carboprost / Q000494:pharmacology*; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D003338:Corpus Luteum / Q000187:drug effects*; D004958:Estradiol / Q000494:pharmacology; D004967:Estrogens / Q000494:pharmacology*; D004997:Ethinyl Estradiol / Q000494:pharmacology; D005260:Female; D005333:Fetus / Q000187:drug effects; D008598:Menstruation; D008656:Mestranol / Q000494:pharmacology; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000187:drug effects*; D011374:Progesterone / Q000097:blood; D011461:Prostaglandins F, Synthetic / Q000494:pharmacology*
chemical_list: D006063:Chorionic Gonadotropin; D004967:Estrogens; D011461:Prostaglandins F, Synthetic; D004997:Ethinyl Estradiol; D011374:Progesterone; D004958:Estradiol; D002260:Carboprost; D008656:Mestranol