PET imaging of dopamine D-2 receptors with [F-18]fluoroclebopride in monkeys: Effects of isoflurane- and ketamine-induced anesthesia

The purpose of the present study was to determine whether positron emission tomography (PET) studies in monkeys with the dopamine (DA) D-2 receptor li gand [F-18]fluroclebopride (FCP) would be significantly influenced by anest hetic induction with isoflurane (similar to 5.0%) compared to induction wit h 10 mg/kg ketamine. Five experimentally-naive adult male cynomolgus monkey s (Macaca fascicularis) were trained to sit calmly in a primate restraint c hair. Before thefirst PET scan, each monkey was anesthetized, by mask, with isoflurane. After complete sedation, the monkey was intubated and anesthes ia was maintained throughout the PET study by isoflurane (similar to 1.5%). At least 1 month later, a second PET study was conducted in which anesthes ia was induced with ketamine and maintained by isoflurane (similar to 1.5%) . Irrespective of induction anesthetic, there teas a high uptake of[F-18]FC P and a linear rate of washout from the basal ganglia for all monkeys. Ther e were also MO differences in time to peak uptake (similar to 25 min), in c learance half-life (t(1/2)= 140-164 min) or in D-2 binding (distribution vo lume ratios of 2.48 vs. 2.50). These results indicate that induction anesth etic did not differentially affect D-2 binding of [F-18]FCP in monkeys. Fur thermore, the low variability between studies indicates that [F-18]FCP is a n excellent ligand for longitudinal studies of D-2, receptors in monhuman p rimates. (C) 1999 American College of Neuropsychopharmacology. Published by Elsevier Science Inc.