Co-localization of N-acetyl-aspartyl-glutamate in central cholinergic, noradrenergic, and serotonergic neurons

• Published in: Synapse (New York, N.Y.) Vol. 1; no. 5; p. 455
• Main Authors: Forloni, G, Grzanna, R, Blakely, R D, Coyle, J T
• Format: Journal Article
• Language: English
• Published: United States 1987
• Subjects: Animals; Brain - cytology; Brain - enzymology; Choline O-Acetyltransferase - metabolism; Dipeptides - analysis; Dopamine beta-Hydroxylase - metabolism; Histocytochemistry; Immunohistochemistry; Male; Organ Specificity; Rats; Rats, Inbred Strains; Serotonin - analysis; Spinal Cord - cytology
• ISSN: 0887-4476
• DOI: 10.1002/syn.890010509

An immunohistochemical technique for simultaneously visualizing two different antigens has been used to investigate the presence of the acidic dipeptide, N-acetyl-aspartyl-glutamate (NAAG), in cholinergic, noradrenergic-adrenergic, and serotonergic neurons within CNS. The brain slices were processed sequentially with purified antisera against NAAG and then monoclonal antibody against choline acetyltransferase (ChAT), a marker for cholinergic neurons, or antiserum against dopamine-beta-hydroxylase (DBH), a marker of noradrenergic-adrenergic neurons, or antiserum against serotonin (5HT). Both antigens were revealed by the peroxidase reaction but with different chromogens, which are easily distinguishable. An intense double staining of NAAG-like immunoreactivity (NAAG-LI) and ChAT was observed in the motoneurons of the spinal cord as well as in the several motor components of cranial nerve nuclei including facial, ambiguus, and trigeminal nuclei. A partial colocalization of NAAG-LI and ChAT was evident in the perikarya of the basal forebrain cholinergic system, whereas cholinergic neurons of the medial septum exhibited only sporadic staining for NAAG-LI. A complete coexistence of NAAG-LI and DBH was observed in the locus coeruleus. Most of the other noradrenergic and adrenergic cell groups of the medulla region exhibited substantial co-localization with the exception of the A2 cell group, which was virtually devoid of NAAG-LI. In the dorsal raphe, only a low percentage of serotonergic neurons stained for NAAG-LI. The co-existence of NAAG-LI and serotonin was more evident in the neurons of the median raphe, although the majority of cells failed to show double staining.