Aromatic L-amino acid decarboxylase is present in serotonergic fibers of the striatum of the rat. A double-labeling immunofluorescence study.

The aim of the present study is to examine whether serotonergic fibers of the striatum of the rat contain aromatic L-amino acid decarboxylase (AADC). By use of a double-labeling immunofluorescence method, we showed that AADC was localized in serotonergic fibers of the striatum and cerebral cortex as well as in serotonergic cell bodies of the midbrain raphe nuclei. We previously demonstrated that serotonergic fibers of the rat striatum contained dopamine after intraperitoneal injection of L-dopa. These findings suggest that dopamine is produced from the injected L-dopa in serotonergic fibers of the rat striatum.