Estrogen receptor binding radiopharmaceuticals: II. Tissue distribution of 17 alpha-methylestradiol in normal and tumor-bearing rats.
Tritiated 17 alpha-methylestradiol was synthesized to investigate the potential of the carbon-11-labeled analog as an estrogen-receptor-binding radiopharmaceutical. In vitro, 17 alpha-methylestradiol is bound with high affinity to the cytoplasmic estrogen receptor from rabbit uterus (Kd = 1.96 x 10(-10)M), and it sediments as an 8S hormone-receptor complex in sucrose gradients. The compound shows specific uptake in the uterus of the adult rat, within 1 hr after injection. After 30 min the uterine uptake was 1.73% dose/g. In female rats bearing DMBA-induced tumors, specific uterine and tumor uptakes were observed, although at 30 min the tumor uptake was only 23-30% of the uptake in the uterus. Tritiated 17 alpha-methylestradiol with a specific activity of 6 Ci/mmole showed a similar tissue distribution. Our results indicate that 17 alpha-methylestradiol is promising as an estrogen-receptor-binding radiopharmaceutical.
D015127:9,10-Dimethyl-1,2-benzanthracene; D000818:Animals; D004958:Estradiol / Q000031:analogs & derivatives* / Q000378:metabolism; D005260:Female; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011960:Receptors, Estrogen / Q000378:metabolism; D014018:Tissue Distribution; D014599:Uterus / Q000378:metabolism
D011960:Receptors, Estrogen; C038254:17-methylestradiol; D004958:Estradiol; D015127:9,10-Dimethyl-1,2-benzanthracene