Chemical and Pharmaceutical Bulletin
Online ISSN : 1347-5223
Print ISSN : 0009-2363
ISSN-L : 0009-2363
Regular Articles
Synthesis and Characterization of Novel Radioiodinated Triazole-Pyrolidine Derivative to Detect Orexin 2 Receptor in the Brain
Hiroyuki Watanabe Takuji IdeMasahiro Ono
Author information

2023 Volume 71 Issue 3 Pages 234-239


It is generally accepted that the orexin 2 receptor (OX2R) plays a critical role in the arousal-promoting function, and in vivo imaging of OX2R is expected to contribute to elucidation of orexin systems and the development of drugs to treat sleep disorder. In this study, we newly synthesized and characterized a radioiodinated triazole-pyrolidine derivative ([125I]TPI) to detect OX2R in the brain. In vitro studies using OX1R or OX2R expression cells showed selective binding of [125I]TPI to OX2R. In addition, in vitro autoradiography using rat brain sections showed high accumulation of radioactivity in the OX2R expression region. However, [125I]TPI showed low brain uptake in normal mice. These results suggest that [125I]TPI has a fundamental character to detect OX2R in vitro, but further structural modification to improve brain pharmacokinetics is required to use it for in vivo detection of OX2R.

Fullsize Image
Content from these authors
© 2023 The Pharmaceutical Society of Japan
Previous article Next article