Studies with 17 beta(16 alpha-[125i]iodo)-estradiol, an estrogen receptor-binding radiopharmaceutical, in rats bearing mammary tumors.
We have studied the distribution of 17 beta(16 alpha-[125I]iodo)-estradiol (I-E2) in tumor-bearing and normal rats. High early adrenal-to-blood ratios (up to 22 at 5 min) were seen in all groups, but this fell to six at 1 hr. Uterus-to-blood ratios of 15 were found, and these were fairly constant up to 2 hr after administration. Uptake of label in the uterus, but not in the adrenals, was sensitive to excess diethylstilbestrol, which competes with I-E2 for estrogen receptors. Mean tumor-to-blood ratios of 1.4, 5.5, and 8.7 were seen at 1 hr in rats with transplanted, spontaneous, and N-nitrosomethylurea-induced tumors, respectively. Diethylstilbestrol was shown to reduce uptake of label by spontaneous tumors. Most of the radioactivity was excreted in the bile by 1 hr. Better estrogen-receptor-binding radiopharmaceuticals can probably be designed.
D000230:Adenocarcinoma / Q000000981:diagnostic imaging*; D000311:Adrenal Glands / Q000000981:diagnostic imaging / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D001646:Bile / Q000032:analysis; D004054:Diethylstilbestrol / Q000378:metabolism / Q000494:pharmacology; D004958:Estradiol / Q000378:metabolism*; D005260:Female; D007457:Iodine Radioisotopes / Q000378:metabolism*; D008099:Liver / Q000000981:diagnostic imaging / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008325:Mammary Neoplasms, Experimental / Q000000981:diagnostic imaging*; D008770:Methylnitrosourea / Q000378:metabolism / Q000494:pharmacology; D011877:Radionuclide Imaging; D051381:Rats; D011960:Receptors, Estrogen / Q000378:metabolism*; D014018:Tissue Distribution; D014599:Uterus / Q000000981:diagnostic imaging / Q000187:drug effects / Q000378:metabolism
D007457:Iodine Radioisotopes; D011960:Receptors, Estrogen; D004958:Estradiol; D008770:Methylnitrosourea; D004054:Diethylstilbestrol