Simultaneous detection of tryptamine and dopamine in rat substantia nigra and raphe nuclei using specific antibodies.

Using a double-labelling procedure, morphological relationships existing between dopaminergic and indoleaminergic neuronal systems in the rat brain were investigated. First, thanks to a tryptamine (T) antiserum, we visualized this indoleamine in all mesencephalic regions and showed that the T-immunoreactivity (IR) seems to overlap with the stainings observed from serotonin and 5-methoxytryptamine antisera. Secondly, using a monoclonal anti-dopamine (DA) antibody and our anti-T antibodies, the simultaneous and specific detection of these compounds enabled us to define the spatial relationships existing between the dopaminergic and tryptaminergic neuronal systems from the substantia nigra (SN) to the raphe nuclei. No co-localization existed, but the intensity of T-IR decreased from back to front, whereas the DA-staining decreased in the opposite way, indicating possible interactions at the end of the SN and the B9 area.