A pre-positron emission tomography study of L-3,4-dihydroxy-[3H]phenylalanine distribution in the rat.

The distribution of L-3,4-dihydroxy-[3H]phenylalanine (L-[3H]DOPA) was examined in rats following i.v. injection, to ascertain the possible usefulness of using this ligand to image dopaminergic systems using positron emission tomography. It was found that L-DOPA and its metabolites were preferentially localized in the basal ganglia as compared to other brain regions, and that this preferential localization could be abolished by lesioning of the nigro-striatal tract. The parameters of the L-DOPA uptake and the sensitivity of this uptake to alterations in dopaminergic pathways indicate that this ligand may be useful in visualizing aberrations in dopaminergic pathways in various pathological conditions.