The effect of estrogen antagonism on progesterone production in early pregnancy in the baboon (Papio cynocephalus).
These studies were designed to investigate the role of estrogen on progesterone production in early pregnancy in the baboon, when the contribution of the corpus luteum and placenta has not been established. Oral administration of the estrogen antagonist MER-25 at two dosage levels (15 and 30 mg/kg/day) to the pregnant baboon from days 35 to 55 after conception results in a decline in peripheral plasma levels of progesterone within a few days and persists for at least 20 days after the termination of treatment with no effect on plasma estradiol levels. The same study was done with the use of a different estrogen antagonist, trioxifene mesylate (5 mg/kg/day), and there was no effect on plasma progesterone, although a transient depression in plasma estradiol was evident. These actions may be due to an inherent estrogenicity of trioxifene. In preliminary studies an effect of these estrogen antagonists on placental size and morphology has been observed. Estrogen deprivation in early pregnancy of the baboon results in a depression in plasma progesterone and indicates a placental requirement for estrogen in progesterone product at this stage of pregnancy.
D000022:Abortion, Spontaneous / Q000209:etiology; D000818:Animals; D004958:Estradiol / Q000097:blood*; D004978:Ethamoxytriphetol / Q000008:administration & dosage / Q000494:pharmacology*; D000431:Ethanol / Q000031:analogs & derivatives*; D005260:Female; D010215:Papio / Q000502:physiology*; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011270:Pregnancy, Animal; D011374:Progesterone / Q000097:blood*; D011759:Pyrrolidines / Q000008:administration & dosage / Q000494:pharmacology*
D011759:Pyrrolidines; D000431:Ethanol; D011374:Progesterone; D004958:Estradiol; D004978:Ethamoxytriphetol; C014934:trioxifene