Determination of in vivo Bmax and Kd for 11C-GR103545, an agonist PET tracer for κ-opioid receptors: a study in nonhuman primates.

Unlabelled: The κ-opioid receptors (KOR) are involved in mood disorders and addictive conditions. In vivo imaging studies of this receptor in humans have not been reported because of the lack of a selective ligand. We used a recently developed selective KOR agonist tracer, (11)C-GR103545, and performed a study in rhesus monkeys to estimate the in vivo receptor concentration (Bmax) and dissociation equilibrium constant (Kd).

Equivalence of arterial and venous blood for [11C]CO2-metabolite analysis following intravenous administration of 1-[11C]acetate and 1-[11C]palmitate.

Purpose: Sampling of arterial blood for metabolite correction is often required to define a true radiotracer input function in quantitative modeling of PET data. However, arterial puncture for blood sampling is often undesirable. To establish whether venous blood could substitute for arterial blood in metabolite analysis for quantitative PET studies with 1-[(11)C]acetate and 1-[(11)C]palmitate, we compared the results of [(11)C]CO2-metabolite analyses performed on simultaneously collected arterial and venous blood samples.

A new facile synthetic route to [11C]GSK189254, a selective PET radioligand for imaging of CNS histamine H3 receptor.

GSK189254 and its corresponding precursor GSK185071B were synthesized from 3-methoxyphenylacetic acid with 6-chloropyridine-3-carbolic acid or 6-chloronicotinamide in 8 and 7 steps with either 6% or 7% and either 14% or 16% yield, respectively. [(11)C]GSK189254 was prepared from GSK185071B with [(11)C]CH(3)OTf through N-[(11)C]methylation and isolated by HPLC combined with solid-phase extraction (SPE) in 50-60% radiochemical yield based on [(11)C]CO(2) and decay corrected to end of bombardment (EOB), with 370-740 GBq/μmol specific activity at EOB.

An automated SPE-based high-yield synthesis of [11C]acetate and [11C]palmitate: no liquid-liquid extraction, solvent evaporation or distillation required.

Introduction: An automated method is described for the rapid and high-yield synthesis of two of the most commonly used radioactive fatty acids: [(11)C]acetate and [(11)C]palmitate.

Methods: Reaction of [(11)C]CO(2) with the respective Grignard reagents in diethyl ether solution proceeded for 2 min at 40°C. Quenching of the reaction and liberation of nonreacted [(11)C]CO(2) occurred upon addition of a fourfold molar excess of aqueous 0.

Behavioral depression and positron emission tomography-determined serotonin 1A receptor binding potential in cynomolgus monkeys.

Context: Current animal models of depression are inadequate to further our understanding of depression. New models that allow for analysis of cognitive function and sex differences are needed.

Objective: To characterize serotonin 1A (5-HT(1A)) receptor binding potential (BP) and its relationship with specific characteristics of behavioral depression in cynomolgus monkeys.