Several Radiotracers(i.e. radioligands)
have been developed for PET that are ligands for specific neuroreceptor subtypes such as raclopride, fallypride and desmethoxyfallypride for dopamine D2/D3 receptors, McN 5652 and DASB for serotonin transporters, Mefway for serotonin 5HT1A receptors, Nifene for nicotinic acetylcholine receptors or enzyme substrates e.g. 6-FDOPA for the AADC enzyme.