Table 2.

Summary.

Dopamine accumulates in monoaminergic vesicles where it is completely stable due to a slightly low pH that prevents its autoxidation.

Free dopamine in the cytosol can be oxidized to form neuromelanin through the formation of ortho-quinones such as aminochrome that are potentially neurotoxic.

Aminochrome is a transient metabolite that is formed during neuromelanin synthesis and does not induce a propagative neurotoxic effect towards neighboring neu-rons.