[123/125I]RTI-55, an in vivo label for the serotonin transporter

✍ Scribed by Ursula Scheffel; Robert F. Dannals; Elizabeth J. Cline; George A. Ricaurte; F. Ivy Carroll; Philip Abraham; Anita H. Lewin; Michael J. Kuhar

• Book ID: 104600431
• Publisher: John Wiley and Sons
• Year: 1992
• Tongue: English
• Weight: 582 KB
• Volume: 11
• Category: Article
• ISSN: 0887-4476
• DOI: 10.1002/syn.890110206

✦ Synopsis

lz3I1RTI-55, an iodinated derivative of the cocaine analog 3p-phenyltropane-2P-carboxylic acid methyl ester, was evaluated as a n agent for in vivo labeling of the serotonin transporter. Labeling of the precursor of RTI-55 with 1-123 was efficient and yielded a high specific activity product. After intravenous injection of [1231JRTI-55 into rats, the tracer accumulated in regions with high densities of serotonin and dopamine uptake sites. The distribution of ['"IlRTI-55 binding in areas rich in serotonin uptake sites correlated with [3Hlserotonin uptake measured in vitro in the same regions. Specific L1"I1RTI-55 binding to serotonin uptake sites was inhibited by paroxetine but not by GBR 12,909. Treatment of rats with neurotoxic doses of fenfluramine caused decreases of 66% (in the hypothalamus) to 83% (in the superior colliculi) of specific [lZ5I]RTI-55 binding in all areas except in the striatum and the olfactory tubercles (regions rich in dopamine transporters). These results indicate that [123'12511RTI-55 binds, although not selectively, to the serotonin transporter in vivo. Furthermore, they suggest that ['"I]RTI-55 holds promise as a SPECT imaging agent for the study of the serotonin transporter in humans in health and disease. Published 1992 Wiley-Liss, Inc.