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Seeholzer L. (Don't) take my breath away: Rare epithelial cells in our airways initiate reflexes to guard against harmful stimuli. Science 2024; 385:1428-1429. [PMID: 39325901 DOI: 10.1126/science.ads1317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/28/2024]
Abstract
Rare epithelial cells in our airways initiate reflexes to guard against harmful stimuli.
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Affiliation(s)
- Laura Seeholzer
- Julius Laboratory, University of California, San Francisco, San Francisco, CA, USA
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2
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Seeholzer LF, Julius D. Neuroendocrine cells initiate protective upper airway reflexes. Science 2024; 384:295-301. [PMID: 38669574 PMCID: PMC11407116 DOI: 10.1126/science.adh5483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 02/21/2024] [Indexed: 04/28/2024]
Abstract
Airway neuroendocrine (NE) cells have been proposed to serve as specialized sensory epithelial cells that modulate respiratory behavior by communicating with nearby nerve endings. However, their functional properties and physiological roles in the healthy lung, trachea, and larynx remain largely unknown. In this work, we show that murine NE cells in these compartments have distinct biophysical properties but share sensitivity to two commonly aspirated noxious stimuli, water and acid. Moreover, we found that tracheal and laryngeal NE cells protect the airways by releasing adenosine 5'-triphosphate (ATP) to activate purinoreceptive sensory neurons that initiate swallowing and expiratory reflexes. Our work uncovers the broad molecular and biophysical diversity of NE cells across the airways and reveals mechanisms by which these specialized excitable cells serve as sentinels for activating protective responses.
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Affiliation(s)
- Laura F Seeholzer
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - David Julius
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94143, USA
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3
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Abdali SS, Yokoyama T, Nakamuta N, Saino T, Yamamoto Y. Immunohistochemical analysis of glutamatergic and serotonergic signaling pathways in chemosensory cell clusters in the pharynx and larynx of rats. Tissue Cell 2023; 82:102122. [PMID: 37262979 DOI: 10.1016/j.tice.2023.102122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 05/19/2023] [Accepted: 05/26/2023] [Indexed: 06/03/2023]
Abstract
The present study examined cellular components and the localization of vesicular glutamate transporter (VGLUT) 1 and 2 and serotonin (5-HT) in chemosensory cell clusters in the rat pharynx and larynx. Triple immunolabeling for guanine nucleotide-binding protein G (t), subunit ⍺3 (GNAT3) and nucleoside triphosphate diphosphohydrolase 2 (NTPDase2) with synaptotagmin-1 (Syt1) revealed NTPDase2-immunoreactive type I-like cells in addition to GNAT3-immunoreactive type II-like and Syt1-immunoreactive type III-like cells in pharyngolaryngeal chemosensory cell clusters. Therefore, these clusters appear to comprise similar cell types to those in the lingual taste buds with slight morphological modifications. An immunofluorescence analysis of VGLUT1 or VGLUT2 and GNAT3 with P2X3 purinoceptors revealed that VGLUTs co-localized to P2X3-immunoreactive spherical nerve terminals closely associated with GNAT3-immunoreactive type II-like cells. Moreover, triple immunolabeling for Syt1/synaptosomal-associated protein, 25 kDa (SNAP25) and P2X3 with VGLUT1 or VGLUT2 revealed punctate immunoreactive products for VGLUT1 and VGLUT2 within P2X3-immunoreactive flat axon terminals wrapped around Syt1/SNAP25-immunoreactive type III-like cells. The afferent nerve fibers innervating cell clusters may contain glutamate and release it by exocytosis. On the other hand, immunoreactive products for 5-HT and dopa decarboxylase were detected in Syt1-immunoreactive cells, indicating the release of 5-HT by these cells. The present results suggest that chemosensory cell clusters in the pharynx and larynx may be modulated by intrinsic glutamate and 5-HT.
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Affiliation(s)
- Sayed Sharif Abdali
- Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba, Japan.
| | - Takuya Yokoyama
- Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba, Japan
| | - Nobuaki Nakamuta
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Tomoyuki Saino
- Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba, Japan
| | - Yoshio Yamamoto
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan
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4
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Hernández-Morato I, Yu VX, Pitman MJ. A review of the peripheral proprioceptive apparatus in the larynx. Front Neuroanat 2023; 17:1114817. [PMID: 36910514 PMCID: PMC9998684 DOI: 10.3389/fnana.2023.1114817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 01/19/2023] [Indexed: 03/14/2023] Open
Abstract
The larynx is an organ of the upper airway that participates in breathing, glutition, voice production, and airway protection. These complex functions depend on vocal fold (VF) movement, facilitated in turn by the action of the intrinsic laryngeal muscles (ILM). The necessary precise and near-instantaneous modulation of each ILM contraction relies on proprioceptive innervation of the larynx. Dysfunctional laryngeal proprioception likely contributes to disorders such as laryngeal dystonia, dysphagia, vocal fold paresis, and paralysis. While the proprioceptive system in skeletal muscle derived from somites is well described, the proprioceptive circuitry that governs head and neck structures such as VF has not been so well characterized. For over two centuries, researchers have investigated the question of whether canonical proprioceptive organs, muscle spindles, and Golgi tendon organs, exist in the ILM, with variable findings. The present work is a state-of-the-art review of the peripheral component of laryngeal proprioception, including current knowledge of canonical and possible alternative proprioceptive circuitry elements in the larynx.
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Affiliation(s)
- Ignacio Hernández-Morato
- Department of Otolaryngology-Head and Neck Surgery, Columbia University Irving Medical Center, New York, NY, United States
| | - Victoria X Yu
- Department of Otolaryngology-Head and Neck Surgery, Columbia University Irving Medical Center, New York, NY, United States
| | - Michael J Pitman
- Department of Otolaryngology-Head and Neck Surgery, Columbia University Irving Medical Center, New York, NY, United States
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5
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Yamamoto Y, Moriai H, Yokoyama T, Nakamuta N. Immunohistochemical distribution of proteins involved in glutamate release in subepithelial sensory nerve endings of rat epiglottis. Histochem Cell Biol 2021; 157:51-63. [PMID: 34613496 DOI: 10.1007/s00418-021-02038-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/26/2021] [Indexed: 11/25/2022]
Abstract
To elucidate the efferent functions of sensory nerve endings, the distribution of calretinin and vesicular glutamate transporter 1 (VGLUT1) in laryngeal laminar nerve endings and the immunohistochemical distribution of proteins associated with synaptic vesicle release, i.e., t-SNARE (SNAP25 and syntaxin 1), v-SNARE (VAMP1 and VAMP2), synaptotagmin 1 (Syt1), bassoon, and piccolo, were examined. Subepithelial laminar nerve endings immunoreactive for Na+-K+-ATPase α3-subunit (NKAα3) were largely distributed in the whole-mount preparation of the epiglottic mucosa, and several endings were also immunoreactive for calretinin. VGLUT1 immunoreactivity was observed within terminal part near the outline of the small processes of NKAα3-immunoreactive nerve ending. SNAP25, syntaxin 1, and VAMP1 immunoreactivities were detected in terminal parts of calretinin-immunoreactive endings, whereas VAMP2 immunoreactivity was only observed in a few terminals. Terminal parts immunoreactive for calretinin and/or VGLUT1 also exhibited immunoreactivities for Syt1, Ca2+ sensor for membrane trafficking, and for bassoon and piccolo, presynaptic scaffold proteins. The presence of vesicular release-related proteins, including SNARE proteins, in the terminals of laryngeal laminar endings indicate that intrinsic glutamate modulates their afferent activity in an autocrine-like manner.
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Affiliation(s)
- Yoshio Yamamoto
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, 18-8, Ueda 3-chome, Morioka, Iwate, 020-8550, Japan.
| | - Hisae Moriai
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, 18-8, Ueda 3-chome, Morioka, Iwate, 020-8550, Japan
| | - Takuya Yokoyama
- Department of Anatomy (Cell Biology), Iwate Medical University, 1-1-1 Idaidori, Yahaba, Iwate, 028-3694, Japan
| | - Nobuaki Nakamuta
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, 18-8, Ueda 3-chome, Morioka, Iwate, 020-8550, Japan
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6
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Yamamoto Y, Yokoyama T, Nakamuta N. Morphology of GNAT3-immunoreactive chemosensory cells in the nasal cavity and pharynx of the rat. J Anat 2021; 239:290-306. [PMID: 33677835 PMCID: PMC8273592 DOI: 10.1111/joa.13424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 02/18/2021] [Accepted: 02/19/2021] [Indexed: 10/22/2022] Open
Abstract
Solitary chemosensory cells and chemosensory cell clusters are distributed in the pharynx and larynx. In the present study, the morphology and reflexogenic function of solitary chemosensory cells and chemosensory cell clusters in the nasal cavity and pharynx were examined using immunofluorescence for GNAT3 and electrophysiology. In the nasal cavity, GNAT3-immunoreactive solitary chemosensory cells were widely distributed in the nasal mucosa, particularly in the cranial region near the nostrils. Solitary chemosensory cells were also observed in the nasopharynx. Solitary chemosensory cells in the nasopharyngeal cavity were barrel like or slender in shape with long lateral processes within the epithelial layer to attach surrounding ciliated epithelial cells. Chemosensory cell clusters containing GNAT3-immunoreactive cells were also detected in the pharynx. GNAT3-immunoreactive cells gathered with SNAP25-immunoreactive cells in chemosensory clusters. GNAT3-immunoreactive chemosensory cells were in close contact with a few SP- or CGRP-immunoreactive nerve endings. In the pharynx, GNAT3-immunoreactive chemosensory cells were also attached to P2X3-immunoreactive nerve endings. Physiologically, the perfusion of 10 mM quinine hydrochloride (QHCl) solution induced ventilatory depression. The QHCl-induced reflex was diminished by bilateral section of the glossopharyngeal nerve, suggesting autonomic reflex were evoked by chemosensory cells in pharynx but not in nasal mucosa. The present results indicate that complex shape of nasopharyngeal solitary chemosensory cells may contribute to intercellular communication, and pharyngeal chemosensory cells may play a role in respiratory depression.
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Affiliation(s)
- Yoshio Yamamoto
- Laboratory of Veterinary Anatomy and Cell BiologyFaculty of AgricultureIwate UniversityMoriokaJapan
| | - Takuya Yokoyama
- Department of Anatomy (Cell Biology)Iwate Medical UniversityYahabaJapan
| | - Nobuaki Nakamuta
- Laboratory of Veterinary Anatomy and Cell BiologyFaculty of AgricultureIwate UniversityMoriokaJapan
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7
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Zhuang J, Gao X, Wei W, Pelleg A, Xu F. Intralaryngeal application of ATP evokes apneic response mainly via acting on P2X3 (P2X2/3) receptors of the superior laryngeal nerve in postnatal rats. J Appl Physiol (1985) 2021; 131:986-996. [PMID: 34323594 DOI: 10.1152/japplphysiol.00091.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Aerosolized adenosine 5'-triphosphate (ATP) induces cough and bronchoconstriction by activating vagal sensory fibers' P2X3 and P2X2/3 receptors (P2X3R and P2X2/3R). The goal of this study is to determine the effect of these receptors on the superior laryngeal nerve (SLN)-mediated cardiorespiratory responses to ATP challenge. We compared the cardiorespiratory responses to intralaryngeal perfusion of either ATP or α,β-methylene ATP in rat pups before and after 1) intralaryngeal perfusion of A-317491 (a P2X3R and P2X2/3R antagonist); 2) bilateral section of the SLN; and 3) peri-SLN treatment with capsaicin (to block conduction in superior laryngeal C-fibers, SLCFs) or A-317491. The immunoreactivity (IR) of P2X3R and P2X2R was determined in laryngeal sensory neurons of the nodose/jugular ganglia. Lastly, a whole-cell patch clamp recording was used to determine ATP- or α,β-mATP-induced currents without and with A-317491 treatment. It was found that intralaryngeal perfusion of both ATP and α,β-mATP induced immediate apnea, hypertension, and bradycardia. The apnea was eliminated and the hypertension and bradycardia were blunted by intralaryngeal perfusion of A-317491 and peri-SLN treatment with either A-317491 or capsaicin, while all of the cardiorespiratory responses were abolished by bilateral section of the SLN. P2X3R- and P2X2R-IR were observed in nodose and jugular ganglionic neurons labeled by fluoro-gold (FG). ATP- and α,β-mATP-induced currents recorded in laryngeal C-neurons were reduced by 75% and 95% respectively by application of A-317491. It is concluded that in anesthetized rat pups, the cardiorespiratory responses to intralaryngeal perfusion of either ATP or α,β-mATP are largely mediated by activation of SLCFs' P2X3R-P2X2/3R.
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Affiliation(s)
- Jianguo Zhuang
- Pathophysiology Program, Lovelace Biomedical Institute, Albuquerque, NM, United States
| | - Xiuping Gao
- Pathophysiology Program, Lovelace Biomedical Institute, Albuquerque, NM, United States
| | - Wan Wei
- Pathophysiology Program, Lovelace Biomedical Institute, Albuquerque, NM, United States.,Graduate School, Beijing University of Chinese Medicine, Beijing, China
| | - Amir Pelleg
- Danmir Therapeutics, LLC, Haverford, PA, United States
| | - Fadi Xu
- Pathophysiology Program, Lovelace Biomedical Institute, Albuquerque, NM, United States
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8
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Hirakawa M, Yokoyama T, Yamamoto Y, Saino T. Morphology of P2X3-immunoreactive basket-like afferent nerve endings surrounding serosal ganglia and close relationship with vesicular nucleotide transporter-immunoreactive nerve fibers in the rat gastric antrum. J Comp Neurol 2021; 529:3866-3881. [PMID: 34297862 DOI: 10.1002/cne.25219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 07/05/2021] [Accepted: 07/16/2021] [Indexed: 11/11/2022]
Abstract
We previously reported P2X3 purinoceptor (P2X3)-expressing vagal afferent nerve endings with large web-like structures in the subserosal tissue of the antral lesser curvature, suggesting that these nerve endings were one of the vagal mechanoreceptors. The present study investigated the morphological relationship between P2X3-immunoreactive nerve endings and serosal ganglia in the rat gastric antrum by immunohistochemistry of whole-mount preparations using confocal scanning laser microscopy. P2X3-immunoreactive basket-like subserosal nerve endings with new morphology were distributed laterally to the gastric sling muscles in the distal antrum of the lesser curvature. Parent axons ramified into numerous nerve fibers with pleomorphic flattened structures to form basket-like nerve endings, and the parent axons were originated from large net-like structures of vagal afferent nerve endings. Basket-like nerve endings wrapped around the whole serosal ganglia, which were characterized by neurofilament 200 kDa-immunoreactive neurons with or without neuronal nitric oxide synthase immunoreactivity and S100B-immunoreactive glial cells. Furthermore, basket-like nerve endings were localized in close apposition to dopamine beta-hydroxylase-immunoreactive sympathetic nerve fibers immunoreactive for vesicular nucleotide transporter. These results suggest that P2X3-immunoreactive basket-like nerve endings associated with serosal ganglia are the specialized ending structures of vagal subserosal mechanoreceptors in order to increase the sensitivity during antral peristalsis, and are activated by ATP from sympathetic nerve fibers and/or serosal ganglia for the regulation of mechanoreceptor function.
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Affiliation(s)
- Masato Hirakawa
- Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba, Japan
| | - Takuya Yokoyama
- Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba, Japan
| | - Yoshio Yamamoto
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Tomoyuki Saino
- Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba, Japan
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9
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Pathak S, Slovarp L, Clary MS, Jetté ME. Laryngeal Chemoreflex in Health and Disease: A Review. Chem Senses 2021; 45:823-831. [PMID: 33247587 DOI: 10.1093/chemse/bjaa069] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The larynx plays a key role in airway protection via the laryngeal chemoreflex (LCR). This involuntary reflex can be evoked when hazardous substances activate mucosal receptors, which send signals to be processed within the brainstem. Although the LCR is meant to be protective, the reflex can become hyperstimulated, even to benign stimuli, which can result in pathological disorders, such as chronic cough and inducible laryngeal obstruction. In this review, we will outline the mechanism of the LCR and its associated pathological disorders.
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Affiliation(s)
- Shivani Pathak
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, University of Colorado, Aurora, CO, USA
| | - Laurie Slovarp
- School of Speech, Language, Hearing, & Occupational Sciences, University of Montana, Missoula, MT, USA
| | - Matthew S Clary
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, University of Colorado, Aurora, CO, USA
| | - Marie E Jetté
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, University of Colorado, Aurora, CO, USA
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10
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Foote AG, Thibeault SL. Sensory Innervation of the Larynx and the Search for Mucosal Mechanoreceptors. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2021; 64:371-391. [PMID: 33465318 PMCID: PMC8632506 DOI: 10.1044/2020_jslhr-20-00350] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 09/19/2020] [Accepted: 10/28/2020] [Indexed: 05/03/2023]
Abstract
Purpose The larynx is a uniquely situated organ, juxtaposed between the gastrointestinal and respiratory tracts, and endures considerable immunological challenges while providing reflexogenic responses via putative mucosal mechanoreceptor afferents. Laryngeal afferents mediate precise monitoring of sensory events by relay to the internal branch of the superior laryngeal nerve (iSLN). Exposure to a variety of stimuli (e.g., mechanical, chemical, thermal) at the mucosa-airway interface has likely evolved a diverse array of specialized sensory afferents for rapid laryngeal control. Accordingly, mucosal mechanoreceptors in demarcated laryngeal territories have been hypothesized as primary sources of sensory input. The purpose of this article is to provide a tutorial on current evidence for laryngeal afferent receptors in mucosa, the role of mechano-gated ion channels within airway epithelia and mechanisms for mechanoreceptors implicated in laryngeal health and disease. Method An overview was conducted on the distribution and identity of iSLN-mediated afferent receptors in the larynx, with specific focus on mechanoreceptors and their functional roles in airway mucosa. Results/Conclusions Laryngeal somatosensation at the cell and molecular level is still largely unexplored. This tutorial consolidates various animal and human researches, with translational emphasis provided for the importance of mucosal mechanoreceptors to normal and abnormal laryngeal function. Information presented in this tutorial has relevance to both clinical and research arenas. Improved understanding of iSLN innervation and corresponding mechanotransduction events will help shed light upon a variety of pathological reflex responses, including persistent cough, dysphonia, and laryngospasm.
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Affiliation(s)
- Alexander G. Foote
- Division of Otolaryngology–Head and Neck Surgery, University of Wisconsin–Madison
| | - Susan L. Thibeault
- Division of Otolaryngology–Head and Neck Surgery, University of Wisconsin–Madison
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11
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Liu J, Hu YS, Tang Y. Commentary: Vagal P2RY1 Receptors: A Novel Target for Airway Disease. Front Pharmacol 2021; 11:596003. [PMID: 33390983 PMCID: PMC7774324 DOI: 10.3389/fphar.2020.596003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 10/09/2020] [Indexed: 11/18/2022] Open
Affiliation(s)
- Juan Liu
- School of Sports Medicine and Health, Chengdu Sport University, Chengdu, China.,Sports Medicine Key Laboratory of Sichuan Province, Chengdu, China
| | - Yu-Shi Hu
- School of Sports Medicine and Health, Chengdu Sport University, Chengdu, China.,Sports Medicine Key Laboratory of Sichuan Province, Chengdu, China
| | - Yong Tang
- School of Sports Medicine and Health, Chengdu Sport University, Chengdu, China.,Sports Medicine Key Laboratory of Sichuan Province, Chengdu, China
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12
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Hirakawa M, Yokoyama T, Yamamoto Y, Saino T. Distribution and morphology of P2X3-immunoreactive subserosal afferent nerve endings in the rat gastric antrum. J Comp Neurol 2020; 529:2014-2028. [PMID: 33190284 DOI: 10.1002/cne.25069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 10/27/2020] [Accepted: 11/09/2020] [Indexed: 12/15/2022]
Abstract
The present study investigated the morphological characteristics of subserosal afferent nerve endings with immunoreactivity for the P2X3 purinoceptor (P2X3) in the rat stomach by immunohistochemistry of whole-mount preparations using confocal scanning laser microscopy. P2X3 immunoreactivity was observed in subserosal nerve endings proximal and lateral to the gastric sling muscles in the distal antrum of the lesser curvature. Parent axons ramified into several lamellar processes to form net-like complex structures that extended two-dimensionally in every direction on the surface of the longitudinal smooth muscle layer. The axon terminals in the periphery of P2X3-immunoreactive net-like structures were flat and looped or leaf-like in shape. Some net-like lamellar structures and their axon terminals with P2X3 immunoreactivity were also immunoreactive for P2X2. P2X3-immunoreactive nerve fibers forming net-like terminal structures were closely surrounded by S100B-immunoreactive terminal Schwann cells, whereas axon terminals twined around these cells and extended club-, knob-, or thread-like protrusions in the surrounding tissues. Furthermore, a retrograde tracing method using fast blue dye indicated that most of these nerve endings originated from the nodose ganglia of the vagus nerve. These results suggest that P2X3-immunoreactive subserosal nerve endings have morphological characteristics of mechanoreceptors and contribute to sensation of a mechanical deformation of the distal antral wall associated with antral peristalsis.
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Affiliation(s)
- Masato Hirakawa
- Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba-cho, Japan
| | - Takuya Yokoyama
- Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba-cho, Japan
| | - Yoshio Yamamoto
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Tomoyuki Saino
- Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba-cho, Japan
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13
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Taylor-Clark TE. Molecular identity, anatomy, gene expression and function of neural crest vs. placode-derived nociceptors in the lower airways. Neurosci Lett 2020; 742:135505. [PMID: 33197519 DOI: 10.1016/j.neulet.2020.135505] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 11/02/2020] [Accepted: 11/09/2020] [Indexed: 12/11/2022]
Abstract
The lower airways (larynx to alveoli) are protected by a complex array of neural networks that regulate respiration and airway function. Harmful stimuli trigger defensive responses such as apnea, cough and bronchospasm by activating a subpopulation of sensory afferent nerves (termed nociceptors) which are found throughout the airways. Airway nociceptive fibers are projected from the nodose vagal ganglia, the jugular vagal ganglia and the dorsal root ganglia, which are derived from distinct embryological sources: the former from the epibranchial placodes, the latter two from the neural crest. Embryological source determines nociceptive gene expression of receptors and neurotransmitters and recent evidence suggests that placode- and neural crest-derived nociceptors have distinct stimuli sensitivity, innervation patterns and functions. Improved understanding of the function of each subset in specific reflexes has substantial implications for therapeutic targeting of the neuronal components of airway disease such as asthma, viral infections and chronic obstructive pulmonary disease.
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Affiliation(s)
- Thomas E Taylor-Clark
- Molecular Pharmacology & Physiology, Morsani College of Medicine, University of South Florida, 12901 Bruce B Downs Blvd., Tampa, FL 33612, USA.
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14
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Hossain MZ, Ando H, Unno S, Kitagawa J. Targeting Chemosensory Ion Channels in Peripheral Swallowing-Related Regions for the Management of Oropharyngeal Dysphagia. Int J Mol Sci 2020; 21:E6214. [PMID: 32867366 PMCID: PMC7503421 DOI: 10.3390/ijms21176214] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 08/24/2020] [Accepted: 08/26/2020] [Indexed: 12/22/2022] Open
Abstract
Oropharyngeal dysphagia, or difficulty in swallowing, is a major health problem that can lead to serious complications, such as pulmonary aspiration, malnutrition, dehydration, and pneumonia. The current clinical management of oropharyngeal dysphagia mainly focuses on compensatory strategies and swallowing exercises/maneuvers; however, studies have suggested their limited effectiveness for recovering swallowing physiology and for promoting neuroplasticity in swallowing-related neuronal networks. Several new and innovative strategies based on neurostimulation in peripheral and cortical swallowing-related regions have been investigated, and appear promising for the management of oropharyngeal dysphagia. The peripheral chemical neurostimulation strategy is one of the innovative strategies, and targets chemosensory ion channels expressed in peripheral swallowing-related regions. A considerable number of animal and human studies, including randomized clinical trials in patients with oropharyngeal dysphagia, have reported improvements in the efficacy, safety, and physiology of swallowing using this strategy. There is also evidence that neuroplasticity is promoted in swallowing-related neuronal networks with this strategy. The targeting of chemosensory ion channels in peripheral swallowing-related regions may therefore be a promising pharmacological treatment strategy for the management of oropharyngeal dysphagia. In this review, we focus on this strategy, including its possible neurophysiological and molecular mechanisms.
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Affiliation(s)
- Mohammad Zakir Hossain
- Department of Oral Physiology, School of Dentistry, Matsumoto Dental University, 1780 Gobara Hirooka, Shiojiri, Nagano 399-0781, Japan;
| | - Hiroshi Ando
- Department of Biology, School of Dentistry, Matsumoto Dental University, 1780 Gobara, Hirooka, Shiojiri, Nagano 399-0781, Japan;
| | - Shumpei Unno
- Department of Oral Physiology, School of Dentistry, Matsumoto Dental University, 1780 Gobara Hirooka, Shiojiri, Nagano 399-0781, Japan;
| | - Junichi Kitagawa
- Department of Oral Physiology, School of Dentistry, Matsumoto Dental University, 1780 Gobara Hirooka, Shiojiri, Nagano 399-0781, Japan;
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Prescott SL, Umans BD, Williams EK, Brust RD, Liberles SD. An Airway Protection Program Revealed by Sweeping Genetic Control of Vagal Afferents. Cell 2020; 181:574-589.e14. [PMID: 32259485 PMCID: PMC7197391 DOI: 10.1016/j.cell.2020.03.004] [Citation(s) in RCA: 120] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 02/08/2020] [Accepted: 03/04/2020] [Indexed: 12/22/2022]
Abstract
Sensory neurons initiate defensive reflexes that ensure airway integrity. Dysfunction of laryngeal neurons is life-threatening, causing pulmonary aspiration, dysphagia, and choking, yet relevant sensory pathways remain poorly understood. Here, we discover rare throat-innervating neurons (∼100 neurons/mouse) that guard the airways against assault. We used genetic tools that broadly cover a vagal/glossopharyngeal sensory neuron atlas to map, ablate, and control specific afferent populations. Optogenetic activation of vagal P2RY1 neurons evokes a coordinated airway defense program-apnea, vocal fold adduction, swallowing, and expiratory reflexes. Ablation of vagal P2RY1 neurons eliminates protective responses to laryngeal water and acid challenge. Anatomical mapping revealed numerous laryngeal terminal types, with P2RY1 neurons forming corpuscular endings that appose laryngeal taste buds. Epithelial cells are primary airway sentinels that communicate with second-order P2RY1 neurons through ATP. These findings provide mechanistic insights into airway defense and a general molecular/genetic roadmap for internal organ sensation by the vagus nerve.
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Affiliation(s)
- Sara L Prescott
- Howard Hughes Medical Institute, Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Benjamin D Umans
- Howard Hughes Medical Institute, Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Erika K Williams
- Howard Hughes Medical Institute, Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Rachael D Brust
- Howard Hughes Medical Institute, Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Stephen D Liberles
- Howard Hughes Medical Institute, Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
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16
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Yokoyama T, Yamamoto Y, Hirakawa M, Kato K, Saino T. Vesicular nucleotide transporter-immunoreactive type I cells associated with P2X3-immunoreactive nerve endings in the rat carotid body. J Comp Neurol 2019; 528:1486-1501. [PMID: 31808543 DOI: 10.1002/cne.24837] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 11/21/2019] [Accepted: 12/02/2019] [Indexed: 12/23/2022]
Abstract
ATP is the major excitatory transmitter from chemoreceptor type I cells to sensory nerve endings in the carotid body, and has been suggested to be released by exocytosis from these cells. We investigated the mRNA expression and immunohistochemical localization of vesicular nucleotide transporter (VNUT) in the rat carotid body. RT-PCR detected mRNA expression of VNUT in extracts of the tissue. Immunoreactivity for VNUT was localized in a part of type I cells immunoreactive for synaptophysin (SYN), but not in glial-like type II cells immunoreactive for S100 and S100B. Among SYN-immunoreactive type I cells, VNUT immunoreactivity was selectively localized in the sub-population of tyrosine hydroxylase (TH)-immunorective type I cells associated with nerve endings immunoreactive for the P2X3 purinoceptor; however, it was not detected in the sub-population of type I cells immunoreactive for dopamine beta-hydroxylase. Multi-immunolabeling for VNUT, P2X3, and Bassoon revealed that Bassoon-immunoreactive products were localized in type I cells with VNUT immunoreactivity, and accumulated on the contact side of P2X3-immunoreactive nerve endings. These results revealed the selective localization of VNUT in the subpopulation of TH-immunoreactive type I cells attached to sensory nerve endings and suggested that these cells release ATP by exocytosis for chemosensory transmission in the carotid body.
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Affiliation(s)
- Takuya Yokoyama
- Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba, Japan
| | - Yoshio Yamamoto
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Masato Hirakawa
- Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba, Japan
| | - Kouki Kato
- Center for Laboratory Animal Science, National Defense Medical College, Tokorozawa, Japan
| | - Tomoyuki Saino
- Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba, Japan
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17
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Masuda H, Nakamuta N, Yamamoto Y. Morphology of GNAT3-immunoreactive chemosensory cells in the rat larynx. J Anat 2018; 234:149-164. [PMID: 30467855 DOI: 10.1111/joa.12914] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/24/2018] [Indexed: 01/07/2023] Open
Abstract
The upper airways play important roles in respiratory defensive reflexes. Although solitary chemosensory cells and chemosensory cell clusters have been reported in the laryngeal mucosa of mammalian species, the distribution and cellular morphology of chemosensory cells remain unclear. In the present study, the distribution and morphology of solitary chemosensory cells and chemosensory cell clusters were examined by immunofluorescence for GNAT3 on whole-mount preparations of the rat laryngeal mucosa. Electrophysiological experiments were performed to analyze the respiratory reflexes evoked by bitter stimuli to the laryngeal cavity. In the whole area of the laryngeal mucosa, the numbers of GNAT3-immunoreactive solitary chemosensory cells and chemosensory clusters were 421.0 ± 20.3 and 62.7 ± 6.9, respectively. GNAT3-immunoreactive solitary chemosensory cells were mainly distributed in the mucosa overlying epiglottic and arytenoid cartilage, and chemosensory clusters were mainly distributed on the edge of the epiglottis and aryepiglottic fold. GNAT3-immunoreactive solitary chemosensory cells were slender with elongated processes or had a flask-like/columnar shape. The number of GNAT3-immunoreactive cells in chemosensory clusters was 6.1 ± 0.4, ranging between 2 and 14 cells. GNAT3-immunoreactive cells in the cluster were variform and the tips of apical processes gathered at one point at the surface of the epithelium. The tips of apical cytoplasmic processes in solitary chemosensory cells and cells in the cluster were immunoreactive for espin, and faced the laryngeal cavity. Physiological experiments showed that the application of 10 mm quinine hydrochloride to the laryngeal cavity decreased respiratory frequency. The present results revealed the chemosensory field of the larynx and the morphological characteristics of the laryngeal chemosensory system for respiratory depression.
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Affiliation(s)
- Haruka Masuda
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Nobuaki Nakamuta
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Yoshio Yamamoto
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan
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18
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Triantafyllou A, Devaney KO, Hunt JL, Rinaldo A, Ferlito A. Structural biology of intraepithelial neuroendocrine cells in the larynx: Literature review. Pathol Res Pract 2018; 215:1-4. [PMID: 30396757 DOI: 10.1016/j.prp.2018.10.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Revised: 10/21/2018] [Accepted: 10/22/2018] [Indexed: 12/01/2022]
Abstract
Current knowledge of laryngeal neuroendocrine cells in man and other vertebrates is reviewed. Particular attention is paid to differences in the distribution of neuroendocrine cells between squamous and respiratory laryngeal mucosa, foetal versus post-natal spatial arrangements, relation to the laryngeal cavity and nerve fibres, and immunoreactivities of these cells. Methodological deficiencies and gaps in knowledge are outlined. Comparisons with neuroendocrine cells in lung and gut are drawn, caution with regard to existing histogenetic models of laryngeal neuroendocrine neoplasia is advised and lines of future research are suggested.
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Affiliation(s)
- Asterios Triantafyllou
- Department of Pathology, Liverpool Clinical Laboratories, Royal Liverpool University Hospital, Liverpool, UK; School of Dentistry, University of Liverpool, Liverpool, UK.
| | | | - Jennifer L Hunt
- Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | | | - Alfio Ferlito
- Coordinator of the International Head and Neck Scientific Group, Padua, Italy
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Distribution and morphology of baroreceptors in the rat carotid sinus as revealed by immunohistochemistry for P2X3 purinoceptors. Histochem Cell Biol 2018; 151:161-173. [PMID: 30244428 DOI: 10.1007/s00418-018-1734-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/18/2018] [Indexed: 01/08/2023]
Abstract
The morphological characteristics of baroreceptors in the rat carotid sinus were reevaluated by whole-mount preparations with immunohistochemistry for P2X3 purinoceptors using confocal scanning laser microscopy. Immunoreactive nerve endings for P2X3 were distributed in the internal carotid artery proximal to the carotid bifurcation, particularly in the region opposite the carotid body. Some pre-terminal axons in nerve endings were ensheathed by myelin sheaths immunoreactive for myelin basic protein. Pre-terminal axons ramified into several branches that extended two-dimensionally in every direction. The axon terminals of P2X3-immunoreactive nerve endings were flat and leaf-like in shape, and extended hederiform- or knob-like protrusions in the adventitial layer. Some axons and axon terminals with P2X3 immunoreactivity were also immunoreactive for P2X2, and axon terminals were closely surrounded by terminal Schwann cells with S100 or S100B immunoreactivity. These results revealed the detailed morphology of P2X3-immunoreactive nerve endings and suggested that these endings respond to a mechanical deformation of the carotid sinus wall with their flat leaf-like terminals.
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20
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Immunohistochemical characterization of brush cells in the rat larynx. J Mol Histol 2017; 49:63-73. [PMID: 29196853 DOI: 10.1007/s10735-017-9747-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 11/28/2017] [Indexed: 01/05/2023]
Abstract
The immunohistochemical characteristics of brush cells in the laryngeal mucosa were examined using immunohistochemistry for various immunohistochemical cell markers including villin at the light and electron microscopic levels. Cells that were immunoreactive to villin were barrel-shaped with thick cytoplasmic processes extending toward the lumen of the laryngeal cavity. Immunoelectron microscopic observations revealed thick and short microvilli with long rootlets of microfilaments. Numerous small clear vesicles and small finger-like cytoplasmic processes were observed in the apical process and lateral membrane, respectively. Double immunofluorescence showed villin-immunoreactive cells were not immunoreactive for the markers of solitary chemosensory cells, GNAT3 and phospholipase C, β2-subunit (PLCβ2), or for that of neuroendocrine cells, synaptosome-associated protein 25kD. Furthermore, immunoreactivities for cytokeratin 18 (CK18) and doublecortin like-kinase 1 in the perinuclear cytoplasm of villin-immunoreactive cells. However, some CK18-immunoreactive cells were immunoreactive to GNAT3 but not to villin. Regarding sensory innervation, only a few intraepithelial nerve endings with P2X3, SP, or CGRP immunoreactivity attached to villin-immunoreactive cells. In the present study, brush cells in the rat laryngeal mucosa were classified by immunoreactivity for villin, and were independent of other non-ciliated epithelial cells such as solitary chemosensory cells and neuroendocrine cells.
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21
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Yamamoto Y, Nakamuta N. Morphology of P2X3-immunoreactive nerve endings in the rat tracheal mucosa. J Comp Neurol 2017; 526:550-566. [PMID: 29124772 DOI: 10.1002/cne.24351] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 10/24/2017] [Accepted: 10/30/2017] [Indexed: 01/28/2023]
Abstract
Nerve endings with immunoreactivity for the P2X3 purinoreceptor (P2X3) in the rat tracheal mucosa were examined by immunohistochemistry of whole-mount preparations with confocal scanning laser microscopy. P2X3 immunoreactivity was observed in ramified endings distributed in the whole length of the trachea. The myelinated parent axons of P2X3-immunoreactive nerve endings ramified into several branches that extended two-dimensionally in every direction at the interface between the epithelial layer and lamina propria. The axonal branches of P2X3-immunoreactive endings branched off many twigs located just beneath the epithelium, and continued to intraepithelial axon terminals. The axon terminals of P2X3-immunoreactive endings were beaded, rounded, or club-like in shape and terminated between tracheal epithelial cells. Flat axon terminals sometimes partly ensheathed neuroendocrine cells with immunoreactivity for SNAP25 or CGRP. Some axons and axon terminals with P2X3 immunoreactivity were immunoreactive for P2X2, while some terminals were immunoreactive for vGLUT2. Furthermore, a retrograde tracing method using fast blue (FB) revealed that 88.4% of FB-labeled cells with P2X3 immunoreactivity originated from the nodose ganglion. In conclusion, P2X3-immunoreactive nerve endings in the rat tracheal mucosa have unique morphological characteristics, and these endings may be rapidly adapting receptors and/or irritant receptors that are activated by mucosal irritant stimuli.
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Affiliation(s)
- Yoshio Yamamoto
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Iwate, Japan
| | - Nobuaki Nakamuta
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Iwate, Japan
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23
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Yokoyama T, Saino T, Nakamuta N, Kusakabe T, Yamamoto Y. Three-dimensional architectures of P2X2-/P2X3-immunoreactive afferent nerve terminals in the rat carotid body as revealed by confocal laser scanning microscopy. Histochem Cell Biol 2016; 146:479-88. [DOI: 10.1007/s00418-016-1458-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2016] [Indexed: 12/16/2022]
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