In vitro and in vivo characterization of two C-11-labeled pet tracers for vesicular acetylcholine transporter.
Mol Imaging Biol
; 16(6): 773-80, 2014 Dec.
Article
en En
| MEDLINE
| ID: mdl-24865402
ABSTRACT
PURPOSE:
The vesicular acetylcholine transporter (VAChT) is a specific biomarker for imaging presynaptic cholinergic neurons. Herein, two potent and selective (11)C-labeled VAChT inhibitors were evaluated in rodents and nonhuman primates for imaging VAChT in vivo. PROCEDURES For both (-)-[(11)C]2 and (-)-[(11)C]6, biodistribution, autoradiography, and metabolism studies were performed in male Sprague Dawley rats. Positron emission tomography (PET) brain studies with (-)-[(11)C]2 were performed in adult male cynomolgus macaques; 2 h dynamic data was acquired, and the regions of interest were drawn by co-registration of the PET images with the MRI.RESULTS:
The resolved enantiomers (-)-2 and (-)-6 were very potent and selective for VAChT in vitro (K i < 5 nM for VAChT with >35-fold selectivity for VAChT vs. σ receptors); both radioligands, (-)-[(11)C]2 and (-)-[(11)C]6, demonstrated high accumulation in the VAChT-enriched striatum of rats. (-)-[(11)C]2 had a higher striatum to cerebellum ratio of 2.4-fold at 60 min; at 30 min, striatal uptake reached 0.550 ± 0.086 %ID/g. Uptake was also specific and selective; following pretreatment with (±)-2, striatal uptake of (-)-[(11)C]2 in rats at 30 min decreased by 50 %, while pretreatment with a potent sigma ligand had no significant effect on striatal uptake in rats. In addition, (-)-[(11)C]2 displayed favorable in vivo stability in rat blood and brain. PET studies of (-)-[(11)C]2 in nonhuman primates indicate that it readily crosses the blood-brain barrier (BBB) and provides clear visualization of the striatum; striatal uptake reaches the maximum at 60 min, at which time the target to nontarget ratio reached ~2-fold.CONCLUSIONS:
The radioligand (-)-[(11)C]2 has high potential to be a suitable PET radioligand for imaging VAChT in the brain of living subjects.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Isótopos de Carbono
/
Radiofármacos
/
Proteínas de Transporte Vesicular de Acetilcolina
Límite:
Animals
Idioma:
En
Revista:
Mol Imaging Biol
Asunto de la revista:
BIOLOGIA MOLECULAR
/
DIAGNOSTICO POR IMAGEM
Año:
2014
Tipo del documento:
Article
País de afiliación:
Estados Unidos