Effect of endogenous dopamine on extrastriatal [¹¹C]FLB 457 binding measured by PET.
Central dopaminergic systems are known to be implicated in the pathophysiology of schizophrenia and recent in vivo dopamine receptor imaging studies have focused on the measurement of extrastriatal dopamine receptor. However, there are only a limited number of ligands that can measure the low-density D2 receptor in extrastriatal regions and their sensitivity to endogenous dopamine in extrastriatal regions has not yet been fully examined. In this study, the effect of endogenous dopamine on the extrastriatal binding of [11C]FLB 457 was examined in the rhesus monkey after facilitation with 1 mg/kg of methamphetamine (MAP) and was compared with the effect on the striatal binding of [11C]raclopride. The indices of receptor binding were obtained by four methods using cerebellum as a reference region. The bindings of [11C]FLB 457 in the frontal cortex, temporal cortex, and thalamus were not significantly changed after MAP treatment, while the striatal binding of [11C]raclopride was decreased by more than 20%. These results suggest that [11C]FLB 457 is not sensitive to endogenous dopamine in the extrastriatal regions of rhesus monkeys, despite a sufficient dose of MAP to decrease the binding of [11C]raclopride in the striatum.
Okauchi
T
T
Division of Advanced Technology for Medical Imaging, National Institute of Radiological Sciences, Chiba 263-8555, Japan.
Suhara
T
T
Maeda
J
J
Kawabe
K
K
Obayashi
S
S
Suzuki
K
K
D000818:Animals; D001665:Binding Sites / Q000187:drug effects / Q000502:physiology; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D001931:Brain Mapping; D002250:Carbon Radioisotopes / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism*; D015259:Dopamine Agents / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology*; D065127:Dopamine D2 Receptor Antagonists; D004347:Drug Interactions / Q000502:physiology*; D008253:Macaca mulatta; D008297:Male; D008694:Methamphetamine / Q000494:pharmacology; D017072:Neostriatum / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D011759:Pyrrolidines / Q000378:metabolism*; D020891:Raclopride / Q000494:pharmacology; D011869:Radioligand Assay; D017448:Receptors, Dopamine D2 / Q000819:agonists / Q000378:metabolism; D015203:Reproducibility of Results; D012457:Salicylamides / Q000378:metabolism*; D014055:Tomography, Emission-Computed
D002250:Carbon Radioisotopes; D015259:Dopamine Agents; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D011759:Pyrrolidines; D017448:Receptors, Dopamine D2; D012457:Salicylamides; C065065:FLB 457; D020891:Raclopride; D008694:Methamphetamine; D004298:Dopamine