Cytoplasmic progesterone receptors in the hypothalamus-preoptic area of the mouse: effect of estrogen priming.
A synthetic progestin, R5020, was used to identify cytoplasmic progestin receptors in the hypothalamuspreoptic area (HPOA) of ovariectomized mice. These high-affinity receptors exhibited an apparent dissociation constant of approx. 1 nM. The receptors were specific for progestins. [3H]R5020 binding was inhibited by more than 50% with a 50-fold excess of either radioinert R5020 or progesterone. 5 alpha-Dihydroprogesterone inhibited binding to a lesser extent. 3 alpha-Hydroxy-5 alpha-pregnane-20-one and cortisol did not compete for [3H]R5020 binding. Administration of estradiol benzoate (10 micrograms), 48 h prior to death, resulted in a 54% increase in the HPOA progestin receptor concentration when compared to oil-injected controls. These data demonstrate that there are specific and saturable cytoplasmic progestin receptors in the mouse HPOA and that the concentration of these receptors is increased after estrogen treatment.
D000818:Animals; D001667:Binding, Competitive; D003600:Cytosol / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D007031:Hypothalamus / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D009649:Norpregnadienes / Q000378:metabolism*; D011301:Preoptic Area / Q000378:metabolism*; D011397:Promegestone / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000187:drug effects / Q000378:metabolism*
D009649:Norpregnadienes; D011980:Receptors, Progesterone; D004958:Estradiol; D011397:Promegestone