title: Estrogen derivatives for the external localization of estrogen-dependent malignancy.
abstract: Four radioiodinated estrogen derivatives were studied to determine their affinity for the estrogen-binding protein found in the cytosol of rabbit and rat uteri. In vitro determination of the binding properties by competitive-binding experiments and by sucrose-gradient centrifugation indicates that one of the derivatives, iodohexestrol, binds to the cytosol estrogen-binding protein. This in vitro behavior was related to in vivo distribution. Studies in immature female rats showed high uterine uptake of iodohexestrol at 2 hr (1.69% dose/gm). Iodohexestrol also has a high nonspecific binding in both the blood and the uterine cytosol. Thyroxine can diminish the nonspecific binding in vitro; in vivo the prior injection of thyroxine increased the 2-hr uterus-to-blood ratio from 1.9 to 10.4 The in vitro receptor-assay system was helpful in predicting in vivo distribution.
mesh_terms: D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D003600:Cytosol / Q000032:analysis; D004958:Estradiol; D045166:Estradiol Congeners; D004967:Estrogens; D005260:Female; D006589:Hexestrol / Q000031:analogs & derivatives; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D009369:Neoplasms / Q000175:diagnosis*; D011817:Rabbits; D051381:Rats; D011960:Receptors, Estrogen / Q000032:analysis*; D013974:Thyroxine / Q000494:pharmacology; D014599:Uterus / Q000032:analysis
chemical_list: D045166:Estradiol Congeners; D004967:Estrogens; D007457:Iodine Radioisotopes; D011960:Receptors, Estrogen; D006589:Hexestrol; D004958:Estradiol; D013974:Thyroxine