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.
人们普遍认为,食欲素2受体(OX2R)在唤醒促进功能中起着关键作用,而体内OX2R成像有望帮助阐明食欲素系统,并开发治疗睡眠障碍的药物。在这项研究中,我们新合成了放射性
碘化三唑
吡咯烷衍
生物([125I]
TPI),并对其进行了表征,以检测大脑中的OX2R。使用OX1R或OX2R表达细胞的体外研究表明,[125I]
TPI与OX2R选择性结合。此外,使用大鼠脑切片的体外自动放射摄影显示,放射性物质在OX2R表达区域大量积聚。然而,在正常小鼠中,[125I]
TPI在大脑中的摄取量很低。这些结果表明,[125I]
TPI具有在体外检测OX2R的基本特性,但需要进一步的结构修饰以改善大脑药代动力学,才能用于体内检测OX2R。