Adrenergic neurons in the human brain demonstrated by immunohistochemistry with antibodies to phenylethanolamine N- methyltransferase (PNMT): Discovery of a new group in the nucleus tractussolitarius

Adrenaline neurons in human brain were demonstrated by immunohistochemistry using antibody to phenylethanolamine-N-methyltransferase (PNMT), the final enzyme in the pathway of adrenaline synthesis, using fixed frozen sections and a highly sensitive free floating technique which utilizes metallization. Small densely packed PNMT-immunoreactive neurons were observed to form a nucleus lying just ventrolateral to the area postrema and in the dorsal part of the nucleus tractus solitarius. Larger adrenergic neurons were also present in and around the lateral reticular nucleus and in relationship with the dorsal motor nucleus of the vagus in regions equivalent to the C1 and C2 groups in rats. Longitudinally oriented PNMT-positive axons constitute a subset of tyrosine hydroxylase-immunoreactive axons in the dorsomedial reticular formation.