Kinetics of [11C]N,N-dimethylphenylethylamine in mice and humans: potential for measurement of brain MAO-B activity.

Carbon-11-labeled N,N-dimethylphenylethylamine ([11C]DMPEA) was synthesized by the reaction of N-methylphenylethylamine with [11C]methyl iodide. This newly synthesized radiotracer was developed for the purpose of in vivo measurement of monoamine oxidase-B activity in the brain using a metabolic trapping method. Initially, biodistribution was investigated in mice. The rapid and high uptake of 11C radioactivity in the brain was observed following intravenous injection of [11C]DMPEA, the peak of which was reached at 1 min, followed by a decrease at 1-5 min and slowly thereafter. The kinetics of [11C]DMPEA in the human brain were determined using positron emission tomography (PET) and showed that 11C radioactivity increased gradually over 60 min following initial rapid uptake of 11C radioactivity, with basal ganglia and thalamus showing high accumulation.