Quantitative ex vivo and in vitro receptor autoradiography using 11C-labeled ligands and an imaging plate: a study with a dopamine D2-like receptor ligand [11C]nemonapride.

Ex vivo and in vitro autoradiography (ARG) with radioluminography is a useful technique to characterize newly developed 11C-labeled positron emission tomography (PET) tracers and to apply them to biological and pharmacological studies. In this report, we have described a method of evaluating the radioactivity distribution quantitatively in ex vivo and in vitro ARG using imaging plates and a dopamine D2-like receptor ligand [11C]nemonapride as a model compound. The photo-stimulated luminescence (PSL) values of the rat brain section provided by the imaging plates showed an excellent linear relationship with the radioactivity in a wide range under constant slice-thickness, although the PSL values slightly decreased with increasing slice-thickness both in ex vivo and in vitro ARG. The injection dose of 11C-tracers for ex vivo ARG was also discussed. We found saturable binding sites of [11C]nemonapride in the cortex besides the striatum both ex vivo and in vitro.