Distribution of monoamine oxidase-containing neurons in the grass parakeet (Melopsittacus undulatus) brain

The distribution of monoamine oxidase (MAO)-containing neuronal somata was studied in the grass parakeet (Melopsittacus undulatus) brain by using a histochemical technique involving the coupled peroxidatic oxidation method, and compared with the distribution of the tyrosine hydroxylase-, aromatic L-amino acid decarboxylase-, serotonin-immunoreactive cells in the grass parakeet brain. MAO-containing neurons were located in the nucleus locus coeruleus, around the nucleus n. facialis (nVII), lateral region to the nucleus olivaris inferior and nucleus tractus solitarius, where noradrenaline neurons exist. Another group was located in the ventral region of nervi oculomotorii, caudal region of nucleus n. oculomotorii (nIII), the nucleus raphe and ventral to the nucleus olivaris superior, where serotonin neurons exist. A third group was the non-monoaminergic neurons which were located in the lobus parolfactorius, pareostriatum augmentatum and ventrolateral part of formatio reticularis mesencephali.