Synthesis and evaluation of 1-[2-(4-[11C]methoxyphenyl)phenyl]piperazine for imaging of the serotonin 5-HT7 receptor in the rat brain
摘要:
1-[2-(4-Methoxyphenyl)phenyllpiperazine (4) is a potent serotonin 5-HT7 receptor antagonist (K-i; = 2.6 nM) with a low binding affinity for the 5-HT1A receptor (Ki = 476 nM). As a potential positron emission tomography (PET) radiotracer for the 5-HT7 receptor, [C-11](4) was synthesized at high radiochemical yield and specific activity, by O-[C-11]methylation of 2'-(piperazin-1-yl)[1,1'-biphenyl]-4-ol (6) with [C-11]methyl iodide. Autoradiography revealed that [C-11](4) showed in vitro specific binding with 5-HT7 in the rat brain regions, such as the thalamus which is a region with high 5-HT7 expression. Metabolite analysis indicated that intact [C-11](4) in the brain exceeded 90% of the radioactive components at 15 min after the radiotracer injection, although two radiolabeled metabolites were found in the rat plasma. The PET study of rats showed moderated uptake of [C-11](4) in the brain (1.2 SUV), but no significant regional difference in radioactivity in the brain. Pretreatment with 5-HT7-selective antagonist SB269970 (3) did not decrease the uptake of [C-11](4) in the rat brain. Further studies are warranted that focus on the development of PET ligand candidates with higher binding affinity for 5-HT7 and higher in vivo stability in brain than 4. (C) 2013 Elsevier Ltd. All rights reserved.
Synthesis and evaluation of 1-[2-(4-[11C]methoxyphenyl)phenyl]piperazine for imaging of the serotonin 5-HT7 receptor in the rat brain
摘要:
1-[2-(4-Methoxyphenyl)phenyllpiperazine (4) is a potent serotonin 5-HT7 receptor antagonist (K-i; = 2.6 nM) with a low binding affinity for the 5-HT1A receptor (Ki = 476 nM). As a potential positron emission tomography (PET) radiotracer for the 5-HT7 receptor, [C-11](4) was synthesized at high radiochemical yield and specific activity, by O-[C-11]methylation of 2'-(piperazin-1-yl)[1,1'-biphenyl]-4-ol (6) with [C-11]methyl iodide. Autoradiography revealed that [C-11](4) showed in vitro specific binding with 5-HT7 in the rat brain regions, such as the thalamus which is a region with high 5-HT7 expression. Metabolite analysis indicated that intact [C-11](4) in the brain exceeded 90% of the radioactive components at 15 min after the radiotracer injection, although two radiolabeled metabolites were found in the rat plasma. The PET study of rats showed moderated uptake of [C-11](4) in the brain (1.2 SUV), but no significant regional difference in radioactivity in the brain. Pretreatment with 5-HT7-selective antagonist SB269970 (3) did not decrease the uptake of [C-11](4) in the rat brain. Further studies are warranted that focus on the development of PET ligand candidates with higher binding affinity for 5-HT7 and higher in vivo stability in brain than 4. (C) 2013 Elsevier Ltd. All rights reserved.