In vivo evaluation in cynomolgus monkey brain and metabolism of [18F]fluorodeprenyl: A new MAO-B pet radioligand

In this study, we evaluated the in vivo characteristics of a new monoamine oxidase type B (MAO‐B) radioligand, [18F]fluorodeprenyl, by positron emission tomography (PET) in two cynomolgus monkeys. The brain uptake of [18F]fluorodeprenyl was more than 7% (600% SUV) of the total injected radioactivity and similar to that of [11C]deprenyl, an established MAO‐B radioligand. The highest uptake was observed in the striatum, one of the MAO‐B‐rich regions, with a peak at approximately 2–3 min after injection, followed by lower uptake in the thalamus and the cortex and lowest uptake in the cerebellum. Brain uptake of [18F]fluorodeprenyl was largely inhibited by preadministration of the MAO‐B inhibitor, L‐deprenyl, whereas clorgyline, a MAO Type A blocker, had no significant inhibitory effect, thus demonstrating selectivity for MAO‐B. [18F]Fluorodeprenyl showed relatively slow metabolism with the presence of two radiometabolite peaks with similar retention time as the labeled metabolites of [11C]deprenyl. These results suggest that [18F]fluorodeprenyl is a potential PET radioligand for visualization of MAO‐B activity. Synapse, 2012. © 2011 Wiley Periodicals, Inc.