title: Progestin binding sites in the rat hypothalamus pituitary and uterus.
abstract: Specific, estrogen-inducible, nuclear radioactivity uptake has been demonstrated in the uterus, pituitary and hypothalamus of immature female rats after injection of a highly potent labelled progestin, R 5020 (17, 21-dimethyl-19-nor-pregna-4, 9-diene-3, 20-dione). A cytoplasmic progestin "receptor" has been characterized in these target tissues by an in vitro Dextran-coated charcoal adsorption method. R 5020 binds with the  same intrinsic dissociation constant to the receptor present in these tissues; it dissociates at the same rate from the uterine and pituitary receptor (k-1 = 1 multiplied by 10(-2) min (-1), but about 6 times slower than progesterone. This evidence, together with the similar hormone specificity in the uterus and pituitary, suggests that the progestin "receptor" is a similar entity in central and peripheral target tissues.
mesh_terms: D000818:Animals; D002369:Castration; D002467:Cell Nucleus / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D045166:Estradiol Congeners / Q000494:pharmacology; D005260:Female; D007031:Hypothalamus / Q000378:metabolism*; D009649:Norpregnadienes / Q000378:metabolism*; D010902:Pituitary Gland / Q000378:metabolism*; D045167:Progesterone Congeners / Q000378:metabolism*; D051381:Rats; D011980:Receptors, Progesterone / Q000378:metabolism*; D014599:Uterus / Q000378:metabolism*
chemical_list: D045166:Estradiol Congeners; D009649:Norpregnadienes; D045167:Progesterone Congeners; D011980:Receptors, Progesterone