Phenylethanolamine-N-methyltransferase - immunoreactive nerve terminals afferent to the mouse substantia nigra

In the substantia nigra pars compacta, many phenylethanolamine-N-methyltransferase immunoreactive (PNMT-ir) terminals as well as serotonin-ir terminals were observed for the first time to be very closely situated to the tyrosine hydroxylase (TH)-ir, aromatic L-amino acid decarboxylase-ir, and GTP cyclohydrolase I (GCH)-ir dopaminergic cells [Nagatsu, I., Arai, R., Sakai, M., Yamawaki, Y., Takeuchi, T., Karasawa, N. and Nagatsu, T., Neurosci. Lett., 224 (1997) 185-188]. Immunohistochemical colocalization of TH with GCH or PNMT in the somata and dendrites of TH-positive neurons in the rostral ventrolateral reticular formation of the medulla oblongata (C1 region, [Hokfelt, T., Fuxe, K., Goldstein, M. and Johansson, O., Brain Res., 66 (1974) 235-251]) was proved by a double-labeling immunofluorescence method with a confocal laser-scanning microscope, indicating that the neurons are adrenergic. These results suggest that dopaminergic neurons in the substantia nigra receive PNMT-ir, adrenergic afferents from the C1 region of the medulla oblongata.