In spite of previous efforts, there is lack of a radiotracer for imaging the 5HT1A receptor density in human brain, which is involved in several neurological brain disorders. The aim of this study was to prepare a new derivative of 1-(2-methoxyphenyl)piperazine (MPP) as a main chemical structure of 5HT1A receptor antagonist with 3-carbon linker and radiolabeled by [99mTc][Tc(CO)3(H2O)3]+ precursor. Docking studies before chemical synthesis showed similar fashion of interaction for both WAY100635 (potent 5HT1A receptor antagonist) and new designed ligand, despite of addition of 99mTc(CO)3 group in the structure of new ligand. MPP-(CH2)3-N3 was synthesized via three efficient and reliable chemical synthesis steps (more than 80% yield) then radiolabeled by addition of 2-ethynylpyridine and [99mTc][Tc(CO)3(H2O)3]+ precursor in one pot procedure (more than 95% radiochemical efficiency) through click chemistry method. After incubation, radiotracer was found stable in vitro up to 2 hours. Binding assays showed about 33% specific binding of radiotracer to the 5HT1A receptors. Brain biodistribution studies indicated (0.26 ± 0.05)% ID/g hippocampus uptake at 30 minutes post injection, which its specificity was verified through blocking studies. These results suggested that new designed radioligand might serve as a potent SPECT imaging agent to estimate status of 5HT1A receptors.
尽管之前做了很多努力,但仍缺乏一种放射性示踪剂来成像人脑中的 5HT1A 受体密度,而这种受体与多种脑神经疾病有关。本研究的目的是制备一种新的 1-(2-
甲氧基苯基)
哌嗪(
MPP)衍
生物,作为 5HT1A 受体
拮抗剂的主要
化学结构,并带有 3 个
碳链接,用[99mTc][Tc(CO)3(
H2O)3]+ 前体进行放射性标记。
化学合成前的对接研究表明,尽管新
配体的结构中加入了 99mTc(CO)3 基团,但 WAY100635(强效 5HT1A 受体
拮抗剂)和新设计的
配体的相互作用方式相似。
MPP-(
CH2)3-N3 通过三个高效可靠的
化学合成步骤合成(收率超过 80%),然后通过点击
化学方法,在一锅程序中加入
2-乙炔基吡啶和[99mTc][Tc(CO)3( )3]+ 前体进行放射性标记(放射
化学效率超过 95%)。经过培养后,放射性示踪剂在体外的稳定性可达 2 小时。结合试验显示,放射性示踪剂与 5HT1A 受体的特异性结合率约为 33%。脑
生物分布研究表明,注射后 30 分钟,海马吸收 ID/g 的比例为 (0.26 ± 0.05)%,其特异性通过阻断研究得到了验证。这些结果表明,新设计的放射性
配体可作为一种有效的
SPECT成像剂来评估5HT1A受体的状态。