Estrogen agonistic and antagonistic action of 8 non-steroidal antiestrogens on progestin receptor induction in rat pituitary gland and uterus.
All 8 non-steroidal antiestrogens tested considerably increased progestin receptor concentration in the uterus and, to a lesser extent, in the pituitary of ovariectomized rats. However, the pituitary was more sensitive than the uterus to the estrogen antagonistic action of these compounds, in that monohydroxytamoxifen, LY 117,018, enclomiphene, nitromifen, nafoxidine and trans-tamoxifen completely blocked progestin receptor induction by estradiol benzoate. In these tissues the order of the in vitro binding affinity of antiestrogens to cytoplasmic estrogen receptors was not correlated with either their in vivo estrogen agonistic or antagonistic potency.
D000818:Animals; D004958:Estradiol / Q000378:metabolism; D004965:Estrogen Antagonists / Q000494:pharmacology*; D005260:Female; D007031:Hypothalamus / Q000187:drug effects; D007700:Kinetics; D010902:Pituitary Gland / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D011960:Receptors, Estrogen / Q000187:drug effects; D011980:Receptors, Progesterone / Q000187:drug effects*; D014599:Uterus / Q000187:drug effects*
D004965:Estrogen Antagonists; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D004958:Estradiol