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Lookup NU author(s): Dr Mike Althaus
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Histamine is a mast cell mediator released e.g. during food allergy. The aim of the project was to identify the effect of histamine on rat submucosal neurons and the mechanisms involved. Cultured submucosal neurons from rat colon express H1, H2 and H3 receptors as shown by immunocytochemical staining confirmed by reverse transcriptase polymerase chain reaction (RT-PCR) with messenger RNA (mRNA) isolated from submucosal homogenates as starting material. Histamine evoked a biphasic rise of the cytosolic Ca(2+) concentration in cultured submucosal neurons, consisting in a release of intracellularly stored Ca(2+) followed by an influx from the extracellular space. Although agonists of all three receptor subtypes evoked an increase in the cytosolic Ca(2+) concentration, experiments with antagonists revealed that mainly H1 (and to a lesser degree H2) receptors mediate the response to histamine. In coculture experiments with RBL-2H3 cells, a mast cell equivalent, compound 48/80, evoked an increase in the cytosolic Ca(2+) concentration of neighbouring neurons. Like the response to native histamine, the neuronal response to the mast cell degranulator was strongly inhibited by the H1 receptor antagonist pyrilamine and reduced by the H2 receptor antagonist cimetidine. In rats sensitized against ovalbumin, exposure to the antigen induced a rise in short-circuit current (I sc) across colonic mucosa-submucosa preparations without a significant increase in paracellular fluorescein fluxes. Pyrilamine strongly inhibited the increase in I sc, a weaker inhibition was observed after blockade of protease receptors or 5-lipoxygenase. Consequently, H1 receptors on submucosal neurons seem to play a pivotal role in the communication between mast cells and the enteric nervous system.
Author(s): Bell A, Althaus M, Diener M
Publication type: Article
Publication status: Published
Journal: Pflügers Archiv - European Journal of Physiology
Year: 2015
Volume: 467
Issue: 8
Pages: 1809-1823
Print publication date: 01/08/2015
Online publication date: 16/09/2014
Acceptance date: 04/09/2014
ISSN (print): 0031-6768
ISSN (electronic): 1432-2013
Publisher: Springer
URL: https://doi.org/10.1007/s00424-014-1609-9
DOI: 10.1007/s00424-014-1609-9
PubMed id: 25224285
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