Differential expression of the noradrenaline transporter in adrenergic chromaffin cells, ganglion cells and nerve fibres of the rat adrenal medulla

Expression of the noradrenaline transporter (NAT) was identified in various cell and fibre populations of the rat adrenal medulla, examined with immun ohistochemistry and confocal microscopy. Immunoreactivity for the catechola mine biosynthetic enzymes tyrosine hydroxylase (TH), aromatic-L-amino-acid decarboxylase (AADC) and dopamine beta -hydroxylase (DBH) was present in al l chromaffin cells, while phenylethanolamine N-methyltransferase (PNMT) was used to determine adrenergic chromaffin cell groups. Labelling with NAT an tibody was predominantly cytoplasmic and colocalised with PNMT immunoreacti vity. Noradrenergic chromaffin cells were not NAT immunoreactive. Additiona lly, NAT antibody labelling demonstrated clusters of ganglion cells (presum ably Type I) and nerve fibres. Expression of TH, AADC, DBH, PNMT and NAT mR NA was examined using reverse transcription-polymerase chain reaction (RT-P CR) from adrenal medulla punches and single chromaffin cells, and results w ere consistent with those obtained with immunocytochemistry. Chromaffin cel ls and fibres labelled with antibodies against growth associated protein-43 (GAP-43) were not NAT immunoreactive, while ganglion cells were doubled la belled with the two antibodies. The presence of NAT in adrenergic chromaffi n cells, and its absence from noradrenergic cells, suggests that the adrene rgic cell type is primarily responsible for uptake of catecholamines in the adrenal medulla. (C) 2001 Elsevier Science B.V. All rights reserved.