Synthesis and evaluation of 1-{1-[5-(2′-[18F]Fluoroethyl)-2-thienyl]-cyclohexyl}piperidine as a potential in vivo radioligand for the NMDA receptor-Channel complex

Kazuhiro Orita, Shigeki Sasaki, Minoru Maeda, Atsushi Hashimoto, Toru Nishikawa, Tomoko Yugami, Kohei Umezu

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1-{1-[5-(2′-[18F]Fluoroethyl)-2-thienyl]cyclohexyl}piperidine (18FE-TCP) was prepared as a fluorine-substituted analogue of the potent NMDA receptor channel blocker, 1-[1-(2-thienyl)cyclohexyl]piperidine (TCP), by the mesylate displacement with [18F]fluoride ion with isolated radiochemical yields of 6-12%, and the synthesis time including a two step HPLC purification was 120 min. The regional distribution in rat brain after i.v. injection of 18FE-TCP was heterogeneous and similar to the known distribution of phencyclidine recognition sites, with hippocampus-cerebellum, striatum-cerebellum and cerebral cortex-cerebellum concentration ratios of 2.08, 1.7 and 1.54, respectively, 15 min post-injection. Furthermore, this localized regional cerebral distribution was blocked by co-injection with the unlabelled FE-TCP or pretreatment with cis-2-hydroxymethyl-r-1-(N-piperidyl)-1-(2-thienyl)cyclohexane, with the greatest reductions seen in the hippocampus followed by the striatum and cerebral cortex. However, relatively low receptor binding affinity and high non-specific binding due to its high lipophilicity suggest that 18FE-TCP may not be a suitable radioligand for in vivo PET investigations of the NMDA receptor-channel complex.

Original languageEnglish
Pages (from-to)865-873
Number of pages9
JournalNuclear Medicine and Biology
Issue number7
Publication statusPublished - Oct 1993

All Science Journal Classification (ASJC) codes

  • Molecular Medicine
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

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