Immunohistochemical characterization of nodose cough receptor neurons projecting to the trachea of guinea pigs

Mazzone, Stuart B. and McGovern, Alice E. (2008) Immunohistochemical characterization of nodose cough receptor neurons projecting to the trachea of guinea pigs. Cough, 4 9: 1-16. doi:10.1186/1745-9974-4-9


Author Mazzone, Stuart B.
McGovern, Alice E.
Title Immunohistochemical characterization of nodose cough receptor neurons projecting to the trachea of guinea pigs
Journal name Cough   Check publisher's open access policy
ISSN 1745-9974
Publication date 2008-10-19
Year available 2008
Sub-type Article (original research)
DOI 10.1186/1745-9974-4-9
Open Access Status DOI
Volume 4
Issue 9
Start page 1
End page 16
Total pages 16
Place of publication London, United Kingdom
Publisher BioMed Central
Collection year 2009
Language eng
Subject C1
110901 Autonomic Nervous System
970106 Expanding Knowledge in the Biological Sciences
Formatted abstract
Background
Cough in guinea pigs is mediated in part by capsaicin-insensitive low threshold mechanoreceptors (cough receptors). Functional studies suggest that cough receptors represent a homogeneous population of nodose ganglia-derived sensory neurons. In the present study we set out to characterize the neurochemical profile of cough receptor neurons in the nodose ganglia.

Methods
Nodose neurons projecting to the guinea pig trachea were retrogradely labeled with fluorogold and processed immunohistochemically for the expression of a variety of transporters (Na+/K+/2C1- co-transporter (NKCC1), α1 and α3 Na+/K+ ATPase, vesicular glutamate transporters (vGlut)1 and vGlut2), neurotransmitters (substance P, calcitonin gene-related peptide (CGRP), somatostatin, neuronal nitric oxide synthase (nNOS)) and cytosolic proteins (neurofilament, calretinin, calbindin, parvalbumin).

Results
Fluorogold labeled ~3 per cent of neurons in the nodose ganglia with an average somal perimeter of 137 ± 6.2 μm (range 90–200 μm). All traced neurons (and seemingly all nodose neurons) were immunoreactive for NKCC1. Many (> 90 per cent) were also immunoreactive for vGlut2 and neurofilament and between 50 and 85 per cent expressed α1 ATPase, α3 ATPase or vGlut1. Cough receptor neurons that did not express the above markers could not be differentiated based on somal size, with the exception of neurofilament negative neurons which were significantly smaller (P < 0.05). Less than 10 per cent of fluorogold labeled neurons expressed substance P or CGRP (and these had somal perimeters less than 110 μm) and none expressed somatostatin, calretinin, calbindin or parvalbumin. Two distinct patterns of nNOS labeling was observed in the general population of nodose neurons: most neurons contained cytosolic clusters of moderately intense immunoreactivity whereas less than 10 per cent of neurons displayed uniform intensely fluorescent somal labeling. Less than 3 per cent of the retrogradely traced neurons were intensely fluorescent for nNOS (most showed clusters of nNOS immunoreactivity) and nNOS immunoreactivity was not expressed by cough receptor nerve terminals in the tracheal wall.

Conclusion
These data provide further insights into the neurochemistry of nodose cough receptors and suggest that despite their high degree of functional homogeneity, nodose cough receptors subtypes may eventually be distinguished based on neurochemical profile.
Q-Index Code C1
Q-Index Status Confirmed Code

Document type: Journal Article
Sub-type: Article (original research)
Collections: 2009 Higher Education Research Data Collection
School of Biomedical Sciences Publications
 
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Created: Wed, 08 Apr 2009, 14:37:32 EST by Shirley Rey on behalf of School of Biomedical Sciences