title: Estrogen receptor replenishment. Evidence for receptor recycling.
abstract: Replenishment of uterine estrogen receptor was examined in immature rats following injection of 16 alpha-estradiol. 16 alpha-Estradiol is a "short-acting" estrogen that, after a single injection, stimulates early estrogenic responses (water imbibition, induced protein synthesis, etc.), but not long term responses (DNA synthesis). Replenishment after 16 alpha-estradiol injection was complete within 4 h. Furthermore, disappearance of receptor from the nucleus closely corresponded to a reappearance of receptor in the cytoplasm. In contrast to this, receptor replenishment following injection of 1 microgram of either diethylstilbesterol or 17 beta-estradiol was very slow and lagged behind the disappearance of nuclear receptor, leading to an apparent decrease in total receptor content. Half-lives for the clearance of nuclear estrogen-receptor complexes were estimated to be 30 min for 16 alpha-estradiol and 2 h for 17 beta-estradiol, respectively. Inhibition of protein synthesis by cycloheximide did not inhibit replenishment after 16 alpha-estradiol injection. Studies on replenishment after 17 beta-estradiol injection in the presence of cycloheximide could not be interpreted due to a decrease in total receptor content caused by long term cycloheximide treatment. Multiple injections of 17 alpha-estradiol did not lead to a lag in replenishment time or a decrease in total receptor content. This represents a case in which estrogen receptor replenishment appears to be due entirely to receptor recycling.
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004054:Diethylstilbestrol / Q000494:pharmacology*; D004958:Estradiol / Q000378:metabolism / Q000494:pharmacology*; D004964:Estriol / Q000494:pharmacology*; D005260:Female; D007700:Kinetics; D051381:Rats; D011960:Receptors, Estrogen / Q000187:drug effects / Q000378:metabolism*; D014599:Uterus / Q000378:metabolism*
chemical_list: D011960:Receptors, Estrogen; D004958:Estradiol; D004054:Diethylstilbestrol; D003513:Cycloheximide; D004964:Estriol