AROMATIC AMINO-ACID DECARBOXYLASE (AADC) IMMUNOHISTOCHEMISTRY IN VERTEBRATE BRAIN-STEM WITH AN ANTISERUM RAISED AGAINST AADC MADE IN ESCHERICHIA-COLI

Aromatic L-amino acid decarboxylase (AADC) is involved in the biosynthesis of catecholamines and indolamines. AADC is present in the nervous system, in the chromaffin cells, and in non-neuronal tissues. We tested the capacity of a new polyclonal antibody, obtained by immunization of rabbits with a recombinant protein beta-galactosidase-AADC, to detect monoaminergic neurons in the brainstem as well as monoaminergic paraneurons in the adrenal medulla from goldfish, frog, skink, quail, and mouse. In the adrenal gland we found an immunoreactivity that was consistent with the distributions of the chromaffin cells previously reported. In the brainstem, groups of immunoreactive neurons and several labelled fibers were observed in the five species studied. The raphe region showed cell bodies and processes similar to those previously identified as monoaminergic by other authors. In addition, in medulla oblongata and isthmic tegmentum we found, in goldfish, skink, and quail, neuronal groups similar to mammalian D groups which contain AADC but are devoided of serotonin and catecholamines.