Two new 11C-labelled ligands, N-(3-(4-hydroxyphenyl)propyl)-3-(4-methoxyphenyl)propylamine ([11C]2) and N-(3-(4-hydroxyphenyl)butyl)-3-(4-methoxyphenyl)butylamine ([11C]3) were designed based on bis(phenylalkyl)amines (1) which have been reported as polyamine site antagonists with high-selectivity for NR1A/2B NMDA receptors, and radiolabelling of the corresponding phenol precursors with [11C]methyl iodide was readily accomplished. The in vitro inhibition experiments using rat brain slices showed that [11C]2 and [11C]3 share the binding sites with spermine and/or ifenprodil but not with CP-101,606, a highly potent NR2B-selective NMDA antagonist, and that divalent cations such as Zn2+ produced significant inhibition of both [11C]2 and [11C]3 bindings. Intravenous injection of [11C]3 in mice showed almost homogenous distribution throughout the brain. Attempts to block the tracer uptake of [11C]3 by pre-injection with the unlabelled 3 or spermine in rats were unsuccessful, but a small decrease in the cerebral uptake of [11C]3 by co-treatment with the unlabelled 3 was observed in a monkey PET study. The present findings indicate that none of these 11C-labelled analogues have potential for PET study of binding sites on the N-methly-D-aspartate (NMDA) receptors.
两种新型11C标记的
配体,N-(3-(
4-羟基苯基)丙基)-3-(4-
甲氧基苯基)
丙胺([11C]2)和N-(3-(
4-羟基苯基)丁基)-3-(4-
甲氧基苯基)
丁胺([11C]3),是基于已被报道为高选择性NR1A/2B N
MDA受体
多胺位点拮抗剂的双(苯基烷基)胺(1)设计的,相关的
酚前体与[11C]甲基
碘化物的放射性标记相对容易实现。使用大鼠脑切片进行的体外抑制实验显示,[11C]2和[11C]3与精
氨酸和/或伊非普利共享结合位点,但不与CP-101,606(一种高效的NR2B选择性N
MDA拮抗剂)共享,并且
锌离子(Zn2+)等二价阳离子对[11C]2和[11C]3的结合产生显著抑制。对小鼠进行静脉注射[11C]3后,观察到其在大脑中的分布几乎均匀。在大鼠中尝试通过预注射无标记的3或精
氨酸以阻止[11C]3的示踪剂摄取未成功,但在猴子的PET研究中观察到无标记的3与[11C]3共同处理时脑内摄取有小幅下降。当前的发现表明,这些11C标记的类似物在N
MDA受体结合位点的PET研究中均无潜力。