title: Proximal airway mucous cells of ovalbumin-sensitized and -challenged Brown Norway rats accumulate the neuropeptide calcitonin gene-related peptide.
abstract: Mucous cell hypersecretion and increased neuropeptide production play a role in the exacerbation of symptoms associated with asthma. The source of these neuropeptides have been confined to the contributions of small afferent nerves or possibly neuroendocrine cells. We tested the hypothesis that repeated exposure to allergen would alter the sources and abundance of neuropeptides in airways. Right middle lobes from rats (8 wk old) exposed to 2.5% ovalbumin (OVA) for five episodes (30 min each) or filtered air were inflation fixed with paraformaldehyde. The lobes were dissected to expose the airway tree, permeabilized with DMSO, and incubated in antibody to rat calcitonin gene-related peptide (CGRP), followed with a fluorochrome-labeled second antibody. CGRP-positive structures were imaged via confocal microscopy. Airways were later embedded in plastic and sectioned for cell identification. In animals challenged with OVA, CGRP-positive cells, not neuroendocrine or neuronal in origin (confirmed by a lack of protein gene product 9.5 signal), were recorded along the axial path. In section, this fluorescent signal was localized to granules within epithelial cells. Alcian blue/periodic acid-Schiff staining of these same sections positively identify these cells as mucous cells. Mucous cells of animals not challenged with OVA were not positive for CGRP. We conclude that episodic allergen exposure results in the accumulation of CGRP within mucous cells, creating a new source for the release of this neuropeptide within the airway.
authors.affiliation: Department of Anatomy, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.esschelegle@ucdavis.edu
authors.forename: Shawnessy D
authors.initials: SD
authors.lastname: Larson
authors.forename: Charles G
authors.initials: CG
authors.lastname: Plopper
authors.forename: Greg
authors.initials: G
authors.lastname: Baker
authors.forename: Brian K
authors.initials: BK
authors.lastname: Tarkington
authors.forename: Kendra C
authors.initials: KC
authors.lastname: Decile
authors.forename: Kent
authors.initials: K
authors.lastname: Pinkerton
authors.forename: James K
authors.initials: JK
authors.lastname: Mansoor
authors.forename: Dallas M
authors.initials: DM
authors.lastname: Hyde
authors.forename: Edward S
authors.initials: ES
authors.lastname: Schelegle
mesh_terms: D000485:Allergens / Q000276:immunology / Q000494:pharmacology; D000818:Animals; D001249:Asthma / Q000139:chemically induced / Q000378:metabolism*; D016085:Bronchoconstrictor Agents / Q000494:pharmacology; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism*; D002455:Cell Division; D003857:Deoxyuridine / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D004804:Eosinophils; D008297:Male; D016210:Methacholine Chloride / Q000494:pharmacology; D018613:Microscopy, Confocal; D009077:Mucins / Q000378:metabolism; D010047:Ovalbumin / Q000276:immunology / Q000494:pharmacology; D051381:Rats; D011914:Rats, Inbred BN; D020545:Respiratory Mucosa / Q000166:cytology* / Q000276:immunology / Q000378:metabolism*; D013936:Thymidine / Q000031:analogs & derivatives
chemical_list: D000485:Allergens; D016085:Bronchoconstrictor Agents; D009077:Mucins; D016210:Methacholine Chloride; D010047:Ovalbumin; D015740:Calcitonin Gene-Related Peptide; D013936:Thymidine; D003857:Deoxyuridine