125I-iodinated benzazepines bind to melanin: implications for the noninvasive localization of pigmented melanomas.
Both the 5-R and the 5-S enantiomers of [125I]2,3,4,5-tetrahydro-8-iodo-3-methyl-5-phenyl-1H-3-benzazepin- 7-ol bind to melanin. The interaction between the 5-R enantiomer and melanin permits visualization of melanomas in mice with a noninvasive imaging procedure. Two lines of evidence suggest that the interaction between iodinated ligands and melanin is not related to the D-1 dopamine receptor, a known target for the 5-R enantiomer: first, melanin binds both enantiomers of the 125I-iodinated benzazepine while the D-1 receptor binds only the 5-R enantiomer; second, the melanin binding site displays only a 5-fold difference in affinity towards the R- and S-enantiomers of SCH 23390 while the D-1 receptor displays a 100-fold difference in affinity towards these two molecules. Because both enantiomers of the iodinated benzazepine bind to a human pigmented melanoma, we propose that such compounds may be of use in the diagnosis of pigmented melanoma: in addition, we discuss the possible application of these molecules as a supplement to existing technology for the localization of pigmented melanomas.
D000818:Animals; D014150:Antipsychotic Agents / Q000378:metabolism; D001345:Autoradiography; D001552:Benzazepines / Q000378:metabolism; D001921:Brain / Q000000981:diagnostic imaging; D007457:Iodine Radioisotopes; D008543:Melanins / Q000378:metabolism; D008546:Melanoma, Experimental / Q000000981:diagnostic imaging*; D051379:Mice; D011485:Protein Binding; D011877:Radionuclide Imaging; D051381:Rats; D013237:Stereoisomerism
C049558:8-iodo-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepine-7-ol; D014150:Antipsychotic Agents; D001552:Benzazepines; D007457:Iodine Radioisotopes; D008543:Melanins