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Chemical coding of the human gastrointestinal nervous system: Cholinergic, VIPergic, and catecholaminergic phenotypes
Author(s) -
Anlauf Martin,
Schäfer Martin K.H.,
Eiden Lee,
Weihe Eberhard
Publication year - 2003
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.10599
Subject(s) - catecholaminergic , vesicular acetylcholine transporter , biology , cholinergic , enteric nervous system , cholinergic neuron , tyrosine hydroxylase , catecholaminergic cell groups , dopaminergic , neuroscience , vasoactive intestinal peptide , choline acetyltransferase , dopamine , medicine , neuropeptide , biochemistry , receptor
Abstract The aim of this investigation was to identify the proportional neurochemical codes of enteric neurons and to determine the specific terminal fields of chemically defined nerve fibers in all parts of the human gastrointestinal (GI) tract. For this purpose, antibodies against the vesicular monoamine transporters (VMAT1/2), the vesicular acetylcholine transporter (VAChT), tyrosine hydroxylase (TH), dopamine β‐hydroxylase (DBH), serotonin (5‐HT), vasoactive intestinal peptide (VIP), and protein gene product 9.5 (PGP 9.5) were used. For in situ hybridization 35 S‐labeled VMAT1, VMAT2, and VAChT riboprobes were used. In all regions of the human GI tract, 50–70% of the neurons were cholinergic, as judged by staining for VAChT. The human gut unlike the rodent gut exhibits a cholinergic innervation, which is characterized by an extensive overlap with VIPergic innervation. Neurons containing VMAT2 constituted 14–20% of all intrinsic neurons in the upper GI tract, and there was an equal number of TH‐positive neurons. In contrast, DBH was absent from intrinsic neurons. Cholinergic and monoaminergic phenotypes proved to be completely distinct phenotypes. In conclusion, the chemical coding of human enteric neurons reveals some similarities with that of other mammalian species, but also significant differences. VIP is a cholinergic cotransmitter in the intrinsic innervation of the human gut. The substantial overlap between VMAT2 and TH in enteric neurons indicates that the intrinsic catecholaminergic innervation is a stable component of the human GI tract throughout life. The absence of DBH from intrinsic catecholaminergic neurons indicates that these neurons have a dopaminergic phenotype. J. Comp. Neurol. 459:90–111, 2003. © 2003 Wiley‐Liss, Inc.