Synthesis and biological evaluation of novel carbon-11 labeled pyridyl ethers: candidate ligands for in vivo imaging of α4β2 nicotinic acetylcholine receptors (α4β2-nAChRs) in the brain with positron emission tomography

The most abundant subtype of cerebral nicotinic acetylcholine receptors (nAChR), α4β2, plays a critical role in various brain functions and pathological states. Imaging agents suitable for visualization and quantification of α4β2 nAChRs by positron emission tomography (PET) would present unique opportunities to define the function and pharmacology of the nAChRs in the living human brain. In this study, we report the synthesis, nAChR binding affinity, and pharmacological properties of several novel 3-pyridyl ether compounds. Most of these derivatives displayed a high affinity to the nAChR and a high subtype selectivity for α4β2-nAChR. Three of these novel nAChR ligands were radiolabeled with the positron-emitting isotope 11C and evaluated in animal studies as potential PET radiotracers for imaging of cerebral nAChRs with improved brain kinetics.

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