Nuclear oestrogen receptors in rat liver. Development of assay conditions, characterization and the translocation of oestrogens in vivo.
A method for the determination of specific oestrogen-receptor binding sites in rat liver nuclei is described. Nuclear receptors showed a high affinity for oestradiol (Kd approximately 3 x 10(-9)M), a low capacity, and a distinct specificity for substances with known oestrogenic and anti-oestrogenic activity. No sex differences were seen in the concentrations of nuclear receptors from either vehicle- or ethynyloestradiol-pretreated rats. Only a limited number of binding sites could be extracted with 0.4 M-KCl. The remaining sites, which were solubilized by sonication and treatment with deoxyribonuclease I, sedimented at 3-4 S. Of four oestrogens tested (oestradiol, ethynyloestradiol, diethylstilboestrol, tri-p-anisylchloroethylene), ethynyloestradiol was the most effective translocation agent in vivo, nuclear uptake occurring at doses below 1 microgram/rat; changes in salt extractability of nuclear receptors occurred at doses lower than those required to achieve absolute increases in nuclear receptor concentrations.
D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000378:metabolism; D004967:Estrogens / Q000378:metabolism; D004997:Ethinyl Estradiol / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D008099:Liver / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011960:Receptors, Estrogen / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors
D004967:Estrogens; D011960:Receptors, Estrogen; D004997:Ethinyl Estradiol; D004958:Estradiol