Positron emission tomography imaging of dopamine D2 receptors using a highly selective radiolabeled D2 receptor partial agonist

A series of microPET imaging studies were conducted in anesthetized rhesus monkeys using the dopamine D-2-selective partial agonist, [C-11]SV-III-130. There was a high uptake in regions of brain known to express a high density of D-2 receptors under baseline conditions. Rapid displacement in the caudate and putamen, but not in the cerebellum, was observed after injection of the dopamine D-2/3 receptor nonselective ligand S(-)-eticlopride at a low dosage (0.025 mg/kg/Lv.); no obvious displacement in the caudate, putamen and cerebellum was observed after the treatment with a dopamine D-3 receptor selective ligand WC-34 (0.1 mg/kg/i.v.). Pretreatment with lorazepam (1 mg/kg, i.v. 30 mm) to reduce endogenous dopamine prior to tracer injection resulted in unchanged binding potential (BP) values, a measure of D-2 receptor binding in vivo, in the caudate and putamen. D-Amphetamine challenge studies indicate that there is a significant displacement of [C-11]SV-III-130 by D-Amphetamine-induced increases in synaptic dopamine levels. (C) 2013 Elsevier Inc. All rights reserved.