Evidence for the existence of putative dopamine-, adrenaline- and noradrenaline-containing vagal motor neurons in the brainstem of the rat.

A combined technique utilizing retrograde transport of horseradish peroxidase (HRP) combined with immunocytochemistry using antibodies raised against tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DBH) and phenylethanolamine N-methyl transferase (PNMT) has been used to characterize monoaminergic neurons located within the region of the brainstem vagal motor nucleus. TH-immunoreactive (IR) but not DBH-IR and PNMT-IR neurons were double labelled predominantly at the caudal-most pole of the dorsal motor nucleus of the vagus (dmnX), whereas double-labelled PMNT and DBH plus TH-IR neurons extended from levels just rostral to the obex to 1-2 mm rostrally in the medial and lateral poles of the dmnX, respectively. The presence of putative dopamine (DA), noradrenaline (NA) and adrenaline (A) neurons in topographically distinct regions of the dmnX implicates, DA, NA and A in the modulation of cholinergic transmission at the level of parasympathetic ganglia in discrete parts of the thoracic and abdominal viscera.