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Ustaoglu A, Woodland P. Sensory Phenotype of the Oesophageal Mucosa in Gastro-Oesophageal Reflux Disease. Int J Mol Sci 2023; 24:ijms24032502. [PMID: 36768825 PMCID: PMC9917190 DOI: 10.3390/ijms24032502] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 01/14/2023] [Accepted: 01/18/2023] [Indexed: 02/03/2023] Open
Abstract
Gastroesophageal reflux disease (GORD) affects up to 20% of Western populations, yet sensory mechanisms underlying heartburn pathogenesis remain incompletely understood. While central mechanisms of heartburn perception have been established in earlier studies, recent studies have highlighted an important role of neurochemical, inflammatory, and cellular changes occurring in the oesophageal mucosa itself. The localization and neurochemical characterisation of sensory afferent nerve endings differ among GORD phenotypes, and could explain symptom heterogeneity among patients who are exposed to similar levels of reflux. Acid-induced stimulation of nociceptors on pain-sensing nerve endings can regulate afferent signal transmission. This review considers the role of peripheral mechanisms of sensitization in the amplification of oesophageal sensitivity in patients with GORD.
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Peiris M, Weerts ZZRM, Aktar R, Masclee AAM, Blackshaw A, Keszthelyi D. A putative anti-inflammatory role for TRPM8 in irritable bowel syndrome-An exploratory study. Neurogastroenterol Motil 2021; 33:e14170. [PMID: 34145938 DOI: 10.1111/nmo.14170] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2020] [Revised: 04/08/2021] [Accepted: 04/20/2021] [Indexed: 12/13/2022]
Abstract
BACKGROUND Chronic and recurring pain is a characteristic symptom in irritable bowel syndrome (IBS). Altered signaling between immune cells and sensory neurons within the gut may promote generation of pain symptoms. As transient receptor potential melastatin 8 (TRPM8) agonists, such as L-menthol in peppermint oil, have shown to attenuate IBS pain symptoms, we began investigating potential molecular mechanisms. METHODS Colonic biopsy tissues were collected from patients with IBS and controls, in two separate cohorts. Immunohistochemistry was performed to identify TRPM8 localization. Quantitative PCR was performed to measure mucosal mRNA levels of TRPM8. In addition, functional experiments with the TRPM8 agonist icilin were performed ex vivo to examine cytokine release from biopsies. Daily diaries were collected to ascertain pain symptoms. RESULTS In biopsy tissue from IBS patients, we showed that TRPM8 immunoreactivity is colocalized with immune cells predominantly of the dendritic cell lineage, in close approximation to nerve endings, and TRPM8 protein and mRNA expression was increased in IBS patients compared to controls (p < 0.001). TRPM8 mRNA expression showed a significant positive association with abdominal pain scores (p = 0.015). Treatment of IBS patient biopsies with icilin reduced release of inflammatory cytokines IL-1β, IL-6, and TNF-α (p < 0.05). CONCLUSIONS AND INFERENCES These data indicate TRPM8 may have important anti-inflammatory properties and by this virtue can impact neuro-immune disease mechanisms in IBS.
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Affiliation(s)
- Madusha Peiris
- Wingate Institute for Neurogastroenterology, Centre for Neuroscience, Trauma & Surgery, Blizard Institute, Queen Mary University of London, London, UK
| | - Zsa Zsa R M Weerts
- Division of Gastroenterology & Hepatology, Department of Internal Medicine, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Rubina Aktar
- Wingate Institute for Neurogastroenterology, Centre for Neuroscience, Trauma & Surgery, Blizard Institute, Queen Mary University of London, London, UK
| | - Ad A M Masclee
- Division of Gastroenterology & Hepatology, Department of Internal Medicine, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Ashley Blackshaw
- Wingate Institute for Neurogastroenterology, Centre for Neuroscience, Trauma & Surgery, Blizard Institute, Queen Mary University of London, London, UK
| | - Daniel Keszthelyi
- Division of Gastroenterology & Hepatology, Department of Internal Medicine, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, The Netherlands
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Jin X, Gharibani P, Yin J, Chen JDZ. Neuro-Immune Modulation Effects of Sacral Nerve Stimulation for Visceral Hypersensitivity in Rats. Front Neurosci 2021; 15:645393. [PMID: 34276280 PMCID: PMC8282909 DOI: 10.3389/fnins.2021.645393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 06/01/2021] [Indexed: 11/21/2022] Open
Abstract
Background: Visceral hypersensitivity (VH) is one of the underlying pathophysiologies of irritable bowel syndrome. Mast cell overactivation has been found to be one of the main causes of VH. We investigated the effects and mechanisms of actions of sacral nerve stimulation (SNS) on visceral pain in a rodent model of VH. Methods: The VH was established by an intrarectal infusion of AA in 10-day-old pups. Rats were chronically implanted with electrodes for SNS and recording electromyogram (EMG) and electrocardiogram. The acute study was performed in 2-randomized sessions with SNS (14 Hz, 330 μs, 40% motor threshold or MT, 30 min) or sham-SNS. Later on, rats were randomized into SNS/sham-SNS groups and a chronic study was performed with 2 h-daily SNS or sham-SNS for 21 days. Visceromotor reflexes were assessed by abdominal EMG and withdrawal reflex (AWR). Colon tissues were collected to study colonic acetylcholine (ACh), the enteric neurons (ChAT, nNOS, and PGP9.5), mast cells activity [Tryptase, prostaglandins E2 (PGE2), and cyclooxygenases-2 (COX2)] and pain markers [nerve growth factor (NGF) and Sub-P]. Key Results: Sacral nerve stimulation significantly improved visceromotor reflexes assessed by the EMG and AWR, compared with sham-SNS. SNS normalized the protein expressions of ChAT and nNOS and regulated mast cells activity by downregulating Tryptase, COX2, and PGE2. Neonatal AA administration upregulated NGF and Sub-P; chronic SNS significantly decreased these pain biomarkers. Concurrently, chronic SNS increased ACh in colon tissues and vagal efferent activity. Conclusions: Sacral nerve stimulation reduces VH in rats and this ameliorating effect might be attributed to the suppression of mast cell overactivation in the colon tissue via the modulation of autonomic nervous system functions.
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Affiliation(s)
- Xue Jin
- Division of Gastroenterology and Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Payam Gharibani
- Division of Neuroimmunology, Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Jieyun Yin
- Division of Gastroenterology and Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Jiande D Z Chen
- Division of Gastroenterology and Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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4
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Ustaoglu A, Sawada A, Lee C, Lei WY, Chen CL, Hackett R, Sifrim D, Peiris M, Woodland P. Heartburn sensation in nonerosive reflux disease: pattern of superficial sensory nerves expressing TRPV1 and epithelial cells expressing ASIC3 receptors. Am J Physiol Gastrointest Liver Physiol 2021; 320:G804-G815. [PMID: 33655767 DOI: 10.1152/ajpgi.00013.2021] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The underlying causes of heartburn, characteristic symptom of gastroesophageal reflux disease (GERD), remain incompletely understood. Superficial afferent innervation of the esophageal mucosa in nonerosive reflux disease (NERD) may drive nociceptive reflux perception, but its acid-sensing role has not yet been established. Transient receptor potential vanilloid subfamily member-1 (TRPV1), transient receptor potential melastatin 8 (TRPM8), and acid-sensing ion channel 3 (ASIC3) are regulators of sensory nerve activity and could be important reflux-sensing receptors within the esophageal mucosa. We characterized TRPV1, TRPM8, and ASIC3 expression in esophageal mucosa of patients with GERD. We studied 10 patients with NERD, 10 with erosive reflux disease (ERD), 7 with functional heartburn (FH), and 8 with Barrett's esophagus (BE). Biopsies obtained from the distal esophageal mucosa were costained with TRPV1, TRPM8, or ASIC3, and CGRP, CD45, or E-cadherin. RNA expression of TRPV1, TRPM8, and ASIC3 was assessed using qPCR. Patients with NERD had significantly increased expression of TRPV1 on superficial sensory nerves compared with ERD (P = 0.028) or BE (P = 0.017). Deep intrapapillary nerve endings did not express TRPV1 in all phenotypes studied. ASIC3 was exclusively expressed on epithelial cells most significantly in patients with NERD and ERD (P ≤0.0001). TRPM8 was expressed on submucosal CD45+ leukocytes. Superficial localization of TRPV1-immunoreactive nerves in NERD, and increased ASIC3 coexpression on epithelial cells in NERD and ERD, suggests a mechanism for heartburn sensation. Esophageal epithelial cells may play a sensory role in acid reflux perception and act interdependently with TRPV1-expressing mucosal nerves to augment hypersensitivity in patients with NERD, raising the enticing possibility of topical antagonists for these ion channels as a therapeutic option.NEW & NOTEWORTHY We demonstrate for the first time that increased pain perception in patients with nonerosive reflux disease likely results from expression of acid-sensitive channels on superficial mucosal afferents and esophageal epithelial cells, raising the potential for topical therapy.
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Affiliation(s)
- Ahsen Ustaoglu
- Wingate Institute of Neurogastroenterology, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Akinari Sawada
- Wingate Institute of Neurogastroenterology, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Chung Lee
- Wingate Institute of Neurogastroenterology, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Wei-Yi Lei
- Department of Medicine, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation and Tzu Chi University, Hualien, Taiwan
| | - Chien-Lin Chen
- Department of Medicine, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation and Tzu Chi University, Hualien, Taiwan
| | - Richard Hackett
- Centre for Tumour Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Daniel Sifrim
- Wingate Institute of Neurogastroenterology, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Madusha Peiris
- Wingate Institute of Neurogastroenterology, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Philip Woodland
- Wingate Institute of Neurogastroenterology, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
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Bian Z, Guo T, Jiang S, Chen L, Liu J, Zheng G, Feng B. High-Throughput Functional Characterization of Visceral Afferents by Optical Recordings From Thoracolumbar and Lumbosacral Dorsal Root Ganglia. Front Neurosci 2021; 15:657361. [PMID: 33776645 PMCID: PMC7991386 DOI: 10.3389/fnins.2021.657361] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 02/22/2021] [Indexed: 12/27/2022] Open
Abstract
Functional understanding of visceral afferents is important for developing the new treatment to visceral hypersensitivity and pain. The sparse distribution of visceral afferents in dorsal root ganglia (DRGs) has challenged conventional electrophysiological recordings. Alternatively, Ca2+ indicators like GCaMP6f allow functional characterization by optical recordings. Here we report a turnkey microscopy system that enables simultaneous Ca2+ imaging at two parallel focal planes from intact DRG. By using consumer-grade optical components, the microscopy system is cost-effective and can be made broadly available without loss of capacity. It records low-intensity fluorescent signals at a wide field of view (1.9 × 1.3 mm) to cover a whole mouse DRG, with a high pixel resolution of 0.7 micron/pixel, a fast frame rate of 50 frames/sec, and the capability of remote focusing without perturbing the sample. The wide scanning range (100 mm) of the motorized sample stage allows convenient recordings of multiple DRGs in thoracic, lumbar, and sacral vertebrae. As a demonstration, we characterized mechanical neural encoding of visceral afferents innervating distal colon and rectum (colorectum) in GCaMP6f mice driven by VGLUT2 promotor. A post-processing routine is developed for conducting unsupervised detection of visceral afferent responses from GCaMP6f recordings, which also compensates the motion artifacts caused by mechanical stimulation of the colorectum. The reported system offers a cost-effective solution for high-throughput recordings of visceral afferent activities from a large volume of DRG tissues. We anticipate a wide application of this microscopy system to expedite our functional understanding of visceral innervations.
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Affiliation(s)
- Zichao Bian
- Department of Biomedical Engineering, University of Connecticut, Mansfield, CT, United States
| | - Tiantian Guo
- Department of Biomedical Engineering, University of Connecticut, Mansfield, CT, United States
| | - Shaowei Jiang
- Department of Biomedical Engineering, University of Connecticut, Mansfield, CT, United States
| | - Longtu Chen
- Department of Biomedical Engineering, University of Connecticut, Mansfield, CT, United States
| | - Jia Liu
- Department of Biomedical Engineering, University of Connecticut, Mansfield, CT, United States
| | - Guoan Zheng
- Department of Biomedical Engineering, University of Connecticut, Mansfield, CT, United States
| | - Bin Feng
- Department of Biomedical Engineering, University of Connecticut, Mansfield, CT, United States
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Ustaoglu A, Nguyen A, Spechler S, Sifrim D, Souza R, Woodland P. Mucosal pathogenesis in gastro-esophageal reflux disease. Neurogastroenterol Motil 2020; 32:e14022. [PMID: 33118247 DOI: 10.1111/nmo.14022] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 10/02/2020] [Accepted: 10/05/2020] [Indexed: 12/14/2022]
Abstract
BACKGROUND Despite gastro-esophageal reflux disease affecting up to 20% of Western populations, relatively little is known about the molecular mechanisms underlying its most troublesome symptom: heartburn. Recent findings have unveiled the role of components of the esophageal mucosa in the pathogenesis of GERD including sensory nociceptive nerves and inflammatory mediators. Erosive esophagitis was long believed to develop as a result of acid injury at the esophageal lumen, but novel concepts suggest the generation of reflux-induced esophageal injury as a result of cytokine-mediated inflammation. Moreover, the localization and characterization of mucosal afferent nerves vary between GERD phenotypes and could explain the heterogeneity of symptom perception between patients who experience similar levels of acid reflux. PURPOSE The purpose of this review is to consider the crosstalk of different factors of the esophageal mucosa in the pathogenesis of GERD, with a particular focus on mucosal innervation and molecular basis of acid-induced cytokine response. We discuss the current understanding of the mucosal response to acid injury, the nociceptive role of acid-sensitive receptors expressed in the esophageal mucosa, and the role of esophageal epithelial cells in initiating the onset of erosive esophagitis.
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Affiliation(s)
- Ahsen Ustaoglu
- Wingate Institute of Neurogastroenterology, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Anh Nguyen
- Department of Medicine, Center for Esophageal Diseases, Baylor University Medical Center and Center for Esophageal Research, Baylor Scott & White Research Institute, Dallas, TX, USA
| | - Stuart Spechler
- Department of Medicine, Center for Esophageal Diseases, Baylor University Medical Center and Center for Esophageal Research, Baylor Scott & White Research Institute, Dallas, TX, USA
| | - Daniel Sifrim
- Wingate Institute of Neurogastroenterology, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Rhonda Souza
- Department of Medicine, Center for Esophageal Diseases, Baylor University Medical Center and Center for Esophageal Research, Baylor Scott & White Research Institute, Dallas, TX, USA
| | - Philip Woodland
- Wingate Institute of Neurogastroenterology, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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7
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Supraspinal Mechanisms of Intestinal Hypersensitivity. Cell Mol Neurobiol 2020; 42:389-417. [PMID: 33030712 DOI: 10.1007/s10571-020-00967-3] [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] [Received: 06/05/2020] [Accepted: 09/22/2020] [Indexed: 12/13/2022]
Abstract
Gut inflammation or injury causes intestinal hypersensitivity (IHS) and hyperalgesia, which can persist after the initiating pathology resolves, are often referred to somatic regions and exacerbated by psychological stress, anxiety or depression, suggesting the involvement of both the spinal cord and the brain. The supraspinal mechanisms of IHS remain to be fully elucidated, however, over the last decades the series of intestinal pathology-associated neuroplastic changes in the brain has been revealed, being potentially responsible for the phenomenon. This paper reviews current clinical and experimental data, including the authors' own findings, on these functional, structural, and neurochemical/molecular changes within cortical, subcortical and brainstem regions processing and modulating sensory signals from the gut. As concluded in the review, IHS can develop and maintain due to the bowel inflammation/injury-induced persistent hyperexcitability of viscerosensory brainstem and thalamic nuclei and sensitization of hypothalamic, amygdala, hippocampal, anterior insular, and anterior cingulate cortical areas implicated in the neuroendocrine, emotional and cognitive modulation of visceral sensation and pain. An additional contribution may come from the pathology-triggered dysfunction of the brainstem structures inhibiting nociception. The mechanism underlying IHS-associated regional hyperexcitability is enhanced NMDA-, AMPA- and group I metabotropic receptor-mediated glutamatergic neurotransmission in association with altered neuropeptide Y, corticotropin-releasing factor, and cannabinoid 1 receptor signaling. These alterations are at least partially mediated by brain microglia and local production of cytokines, especially tumor necrosis factor α. Studying the IHS-related brain neuroplasticity in greater depth may enable the development of new therapeutic approaches against chronic abdominal pain in inflammatory bowel disease.
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Abstract
Most of us live blissfully unaware of the orchestrated function that our internal organs conduct. When this peace is interrupted, it is often by routine sensations of hunger and urge. However, for >20% of the global population, chronic visceral pain is an unpleasant and often excruciating reminder of the existence of our internal organs. In many cases, there is no obvious underlying pathological cause of the pain. Accordingly, chronic visceral pain is debilitating, reduces the quality of life of sufferers, and has large concomitant socioeconomic costs. In this review, we highlight key mechanisms underlying chronic abdominal and pelvic pain associated with functional and inflammatory disorders of the gastrointestinal and urinary tracts. This includes how the colon and bladder are innervated by specialized subclasses of spinal afferents, how these afferents become sensitized in highly dynamic signaling environments, and the subsequent development of neuroplasticity within visceral pain pathways. We also highlight key contributing factors, including alterations in commensal bacteria, altered mucosal permeability, epithelial interactions with afferent nerves, alterations in immune or stress responses, and cross talk between these two adjacent organs.
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Affiliation(s)
- Luke Grundy
- Visceral Pain Research Group, College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Bedford Park, South Australia 5042, Australia; .,Centre for Nutrition and Gastrointestinal Diseases, University of Adelaide, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia 5000, Australia
| | - Andelain Erickson
- Visceral Pain Research Group, College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Bedford Park, South Australia 5042, Australia; .,Centre for Nutrition and Gastrointestinal Diseases, University of Adelaide, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia 5000, Australia
| | - Stuart M Brierley
- Visceral Pain Research Group, College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Bedford Park, South Australia 5042, Australia; .,Centre for Nutrition and Gastrointestinal Diseases, University of Adelaide, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia 5000, Australia
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9
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Tikoo S, Barki N, Jain R, Zulkhernain NS, Buhner S, Schemann M, Weninger W. Imaging of mast cells. Immunol Rev 2019; 282:58-72. [PMID: 29431206 DOI: 10.1111/imr.12631] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mast cells are a part of the innate immune system implicated in allergic reactions and the regulation of host-pathogen interactions. The distribution, morphology and biochemical composition of mast cells has been studied in detail in vitro and on tissue sections both at the light microscopic and ultrastructural level. More recently, the development of fluorescent reporter strains and intravital imaging modalities has enabled first glimpses of the real-time behavior of mast cells in situ. In this review, we describe commonly used imaging approaches to study mast cells in cell culture as well as within normal and diseased tissues. We further describe the interrogation of mast cell function via imaging by providing a detailed description of mast cell-nerve plexus interactions in the intestinal tract. Together, visualizing mast cells has expanded our view of these cells in health and disease.
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Affiliation(s)
- Shweta Tikoo
- The Centenary Institute, Newtown, NSW, Australia.,Discipline of Dermatology, Sydney Medical School, Sydney, NSW, Australia
| | - Natasja Barki
- LS Human Biology, Technical University München, München, Germany
| | - Rohit Jain
- The Centenary Institute, Newtown, NSW, Australia.,Discipline of Dermatology, Sydney Medical School, Sydney, NSW, Australia
| | | | - Sabine Buhner
- LS Human Biology, Technical University München, München, Germany
| | - Michael Schemann
- LS Human Biology, Technical University München, München, Germany
| | - Wolfgang Weninger
- The Centenary Institute, Newtown, NSW, Australia.,Discipline of Dermatology, Sydney Medical School, Sydney, NSW, Australia.,Department of Dermatology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
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Brierley SM, Hibberd TJ, Spencer NJ. Spinal Afferent Innervation of the Colon and Rectum. Front Cell Neurosci 2018; 12:467. [PMID: 30564102 PMCID: PMC6288476 DOI: 10.3389/fncel.2018.00467] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 11/16/2018] [Indexed: 12/12/2022] Open
Abstract
Despite their seemingly elementary roles, the colon and rectum undertake a variety of key processes to ensure our overall wellbeing. Such processes are coordinated by the transmission of sensory signals from the periphery to the central nervous system, allowing communication from the gut to the brain via the "gut-brain axis". These signals are transmitted from the peripheral terminals of extrinsic sensory nerve fibers, located within the wall of the colon or rectum, and via their axons within the spinal splanchnic and pelvic nerves to the spinal cord. Recent studies utilizing electrophysiological, anatomical and gene expression techniques indicate a surprisingly diverse set of distinct afferent subclasses, which innervate all layers of the colon and rectum. Combined these afferent sub-types allow the detection of luminal contents, low- and high-intensity stretch or contraction, in addition to the detection of inflammatory, immune, and microbial mediators. To add further complexity, the proportions of these afferents vary within splanchnic and pelvic pathways, whilst the density of the splanchnic and pelvic innervation also varies along the colon and rectum. In this review we traverse this complicated landscape to elucidate afferent function, structure, and nomenclature to provide insights into how the extrinsic sensory afferent innervation of the colon and rectum gives rise to physiological defecatory reflexes and sensations of discomfort, bloating, urgency, and pain.
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Affiliation(s)
- Stuart M Brierley
- Visceral Pain Research Group, Centre for Neuroscience, College of Medicine and Public Health, Flinders University, Bedford Park, SA, Australia.,Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, South Australian Health and Medical Research Institute (SAHMRI), University of Adelaide, Adelaide, SA, Australia
| | - Timothy J Hibberd
- Visceral Neurophysiology Laboratory, Centre for Neuroscience, College of Medicine and Public Health, Flinders University, Bedford Park, SA, Australia
| | - Nick J Spencer
- Visceral Neurophysiology Laboratory, Centre for Neuroscience, College of Medicine and Public Health, Flinders University, Bedford Park, SA, Australia
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Hockley JRF, Smith ESJ, Bulmer DC. Human visceral nociception: findings from translational studies in human tissue. Am J Physiol Gastrointest Liver Physiol 2018; 315:G464-G472. [PMID: 29848022 DOI: 10.1152/ajpgi.00398.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Peripheral sensitization of nociceptors during disease has long been recognized as a leading cause of inflammatory pain. However, a growing body of data generated over the last decade has led to the increased understanding that peripheral sensitization is also an important mechanism driving abdominal pain in highly prevalent functional bowel disorders, in particular, irritable bowel syndrome (IBS). As such, the development of drugs that target pain-sensing nerves innervating the bowel has the potential to be a successful analgesic strategy for the treatment of abdominal pain in both organic and functional gastrointestinal diseases. Despite the success of recent peripherally restricted approaches for the treatment of IBS, not all drugs that have shown efficacy in animal models of visceral pain have reduced pain end points in clinical trials of IBS patients, suggesting innate differences in the mechanisms of pain processing between rodents and humans and, in particular, how we model disease states. To address this gap in our understanding of peripheral nociception from the viscera and the body in general, several groups have developed experimental systems to study nociception in isolated human tissue and neurons, the findings of which we discuss in this review. Studies of human tissue identify a repertoire of human primary afferent subtypes comparable to rodent models including a nociceptor population, the targeting of which will shape future analgesic development efforts. Detailed mechanistic studies in human sensory neurons combined with unbiased RNA-sequencing approaches have revealed fundamental differences in not only receptor/channel expression but also peripheral pain pathways.
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Affiliation(s)
- James R F Hockley
- Department of Pharmacology, University of Cambridge , Cambridge , United Kingdom
| | - Ewan St John Smith
- Department of Pharmacology, University of Cambridge , Cambridge , United Kingdom
| | - David C Bulmer
- Department of Pharmacology, University of Cambridge , Cambridge , United Kingdom
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12
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Contribution of membrane receptor signalling to chronic visceral pain. Int J Biochem Cell Biol 2018; 98:10-23. [DOI: 10.1016/j.biocel.2018.02.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 02/15/2018] [Accepted: 02/19/2018] [Indexed: 12/18/2022]
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13
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Peiris M, Hockley JR, Reed DE, Smith ESJ, Bulmer DC, Blackshaw LA. Peripheral K V7 channels regulate visceral sensory function in mouse and human colon. Mol Pain 2018; 13:1744806917709371. [PMID: 28566000 PMCID: PMC5456027 DOI: 10.1177/1744806917709371] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Background Chronic visceral pain is a defining symptom of many gastrointestinal disorders. The KV7 family (KV7.1–KV7.5) of voltage-gated potassium channels mediates the M current that regulates excitability in peripheral sensory nociceptors and central pain pathways. Here, we use a combination of immunohistochemistry, gut-nerve electrophysiological recordings in both mouse and human tissues, and single-cell qualitative real-time polymerase chain reaction of gut-projecting sensory neurons, to investigate the contribution of peripheral KV7 channels to visceral nociception. Results Immunohistochemical staining of mouse colon revealed labelling of KV7 subtypes (KV7.3 and KV7.5) with CGRP around intrinsic enteric neurons of the myenteric plexuses and within extrinsic sensory fibres along mesenteric blood vessels. Treatment with the KV7 opener retigabine almost completely abolished visceral afferent firing evoked by the algogen bradykinin, in agreement with significant co-expression of mRNA transcripts by single-cell qualitative real-time polymerase chain reaction for KCNQ subtypes and the B2 bradykinin receptor in retrogradely labelled extrinsic sensory neurons from the colon. Retigabine also attenuated responses to mechanical stimulation of the bowel following noxious distension (0–80 mmHg) in a concentration-dependent manner, whereas the KV7 blocker XE991 potentiated such responses. In human bowel tissues, KV7.3 and KV7.5 were expressed in neuronal varicosities co-labelled with synaptophysin and CGRP, and retigabine inhibited bradykinin-induced afferent activation in afferent recordings from human colon. Conclusions We show that KV7 channels contribute to the sensitivity of visceral sensory neurons to noxious chemical and mechanical stimuli in both mouse and human gut tissues. As such, peripherally restricted KV7 openers may represent a viable therapeutic modality for the treatment of gastrointestinal pathologies.
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Affiliation(s)
- Madusha Peiris
- 1 Centre for Neuroscience and Trauma, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - James Rf Hockley
- 2 Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - David E Reed
- 3 GI Diseases Research Unit, Queen's University, Kingston, ON, Canada
| | | | - David C Bulmer
- 1 Centre for Neuroscience and Trauma, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - L Ashley Blackshaw
- 1 Centre for Neuroscience and Trauma, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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14
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McGuire C, Boundouki G, Hockley JRF, Reed D, Cibert-Goton V, Peiris M, Kung V, Broad J, Aziz Q, Chan C, Ahmed S, Thaha MA, Sanger GJ, Blackshaw LA, Knowles CH, Bulmer DC. Ex vivo study of human visceral nociceptors. Gut 2018; 67:86-96. [PMID: 27654583 PMCID: PMC5754853 DOI: 10.1136/gutjnl-2016-311629] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 08/22/2016] [Accepted: 08/23/2016] [Indexed: 12/20/2022]
Abstract
OBJECTIVE The development of effective visceral analgesics free of deleterious gut-specific side effects is a priority. We aimed to develop a reproducible methodology to study visceral nociception in human tissue that could aid future target identification and drug evaluation. DESIGN Electrophysiological (single unit) responses of visceral afferents to mechanical (von Frey hair (VFH) and stretch) and chemical (bradykinin and ATP) stimuli were examined. Thus, serosal afferents (putative nociceptors) were used to investigate the effect of tegaserod, and transient receptor potential channel, vanilloid 4 (TRPV4) modulation on mechanical responses. RESULTS Two distinct afferent fibre populations, serosal (n=23) and muscular (n=21), were distinguished based on their differences in sensitivity to VFH probing and tissue stretch. Serosal units displayed sensitivity to key algesic mediators, bradykinin (6/14 units tested) and ATP (4/10), consistent with a role as polymodal nociceptors, while muscular afferents are largely insensitive to bradykinin (0/11) and ATP (1/10). Serosal nociceptor mechanosensitivity was attenuated by tegaserod (-20.8±6.9%, n=6, p<0.05), a treatment for IBS, or application of HC067047 (-34.9±10.0%, n=7, p<0.05), a TRPV4 antagonist, highlighting the utility of the preparation to examine the mechanistic action of existing drugs or novel analgesics. Repeated application of bradykinin or ATP produced consistent afferent responses following desensitisation to the first application, demonstrating their utility as test stimuli to evaluate analgesic activity. CONCLUSIONS Functionally distinct subpopulations of human visceral afferents can be demonstrated and could provide a platform technology to further study nociception in human tissue.
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Affiliation(s)
- Cian McGuire
- National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - George Boundouki
- Wingate Institute of Neurogastroenterology, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - James R F Hockley
- Wingate Institute of Neurogastroenterology, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - David Reed
- Wingate Institute of Neurogastroenterology, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Vincent Cibert-Goton
- National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Madusha Peiris
- Wingate Institute of Neurogastroenterology, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Victor Kung
- National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - John Broad
- National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Qasim Aziz
- Wingate Institute of Neurogastroenterology, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Christopher Chan
- National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Shafi Ahmed
- National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Mohamed A Thaha
- National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Gareth J Sanger
- National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - L Ashley Blackshaw
- Wingate Institute of Neurogastroenterology, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Charles H Knowles
- National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - David C Bulmer
- National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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15
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Meng Y, Dong L, Sun B, Luo P, Zhang G, Rong W. In Vitro Characterization of the Electrophysiological Properties of Colonic Afferent Fibers in Rats. J Vis Exp 2017. [PMID: 28994815 DOI: 10.3791/56090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Dysfunction of the colonic sensory nerves has been implicated in the pathophysiology of several common conditions, including functional and inflammatory bowel diseases and diabetes. Here, we describe a protocol for the in vitro characterization of the electrophysiological properties of colonic afferents in rats. The colorectum, with the intact pelvic ganglion (PG) attached, is removed from the rat; superfused with carbogenated Krebs solution in the recording chamber; and cannulated at the oral and anal ends to allow for distension. A fine nerve bundle emanating from the PG is identified, and the multiunit afferent nerve activity is recorded using a suction electrode. Distension of the colonic segment elicits gradual increases in multiunit discharge. A principal component analysis is conducted to differentiate the low-threshold, the high-threshold, and the wide-dynamic range afferent fibers. Chemical sensitivity of colonic afferents can be studied through the bath or intraluminal administration of test compounds. This protocol can be modified for application to other species, such as mice and guinea pigs, and to study the differences in the electrophysiological properties of thoracolumbar/hypogastric and lumbosacral/pelvic afferents of the descending colon in normal and pathological conditions.
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Affiliation(s)
- Youqiang Meng
- Hongqiao International Institute of Medical Research, Tongren Hospital and Department of Physiology, Faculty of Basic Medical Sciences, Shanghai Jiaotong University School of Medicine
| | - Li Dong
- Hongqiao International Institute of Medical Research, Tongren Hospital and Department of Physiology, Faculty of Basic Medical Sciences, Shanghai Jiaotong University School of Medicine
| | - Biying Sun
- Hongqiao International Institute of Medical Research, Tongren Hospital and Department of Physiology, Faculty of Basic Medical Sciences, Shanghai Jiaotong University School of Medicine
| | - Ping Luo
- Hongqiao International Institute of Medical Research, Tongren Hospital and Department of Physiology, Faculty of Basic Medical Sciences, Shanghai Jiaotong University School of Medicine
| | - Guohua Zhang
- Hongqiao International Institute of Medical Research, Tongren Hospital and Department of Physiology, Faculty of Basic Medical Sciences, Shanghai Jiaotong University School of Medicine
| | - Weifang Rong
- Hongqiao International Institute of Medical Research, Tongren Hospital and Department of Physiology, Faculty of Basic Medical Sciences, Shanghai Jiaotong University School of Medicine;
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16
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Hockley JRF, González-Cano R, McMurray S, Tejada-Giraldez MA, McGuire C, Torres A, Wilbrey AL, Cibert-Goton V, Nieto FR, Pitcher T, Knowles CH, Baeyens JM, Wood JN, Winchester WJ, Bulmer DC, Cendán CM, McMurray G. Visceral and somatic pain modalities reveal Na V 1.7-independent visceral nociceptive pathways. J Physiol 2017; 595:2661-2679. [PMID: 28105664 DOI: 10.1113/jp272837] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 01/16/2017] [Indexed: 12/17/2022] Open
Abstract
KEY POINTS Voltage-gated sodium channels play a fundamental role in determining neuronal excitability. Specifically, voltage-gated sodium channel subtype NaV 1.7 is required for sensing acute and inflammatory somatic pain in mice and humans but its significance in pain originating from the viscera is unknown. Using comparative behavioural models evoking somatic and visceral pain pathways, we identify the requirement for NaV 1.7 in regulating somatic (noxious heat pain threshold) but not in visceral pain signalling. These results enable us to better understand the mechanisms underlying the transduction of noxious stimuli from the viscera, suggest that the investigation of pain pathways should be undertaken in a modality-specific manner and help to direct drug discovery efforts towards novel visceral analgesics. ABSTRACT Voltage-gated sodium channel NaV 1.7 is required for acute and inflammatory pain in mice and humans but its significance for visceral pain is unknown. Here we examine the role of NaV 1.7 in visceral pain processing and the development of referred hyperalgesia using a conditional nociceptor-specific NaV 1.7 knockout mouse (NaV 1.7Nav1.8 ) and selective small-molecule NaV 1.7 antagonist PF-5198007. NaV 1.7Nav1.8 mice showed normal nociceptive behaviours in response to intracolonic application of either capsaicin or mustard oil, stimuli known to evoke sustained nociceptor activity and sensitization following tissue damage, respectively. Normal responses following induction of cystitis by cyclophosphamide were also observed in both NaV 1.7Nav1.8 and littermate controls. Loss, or blockade, of NaV 1.7 did not affect afferent responses to noxious mechanical and chemical stimuli in nerve-gut preparations in mouse, or following antagonism of NaV 1.7 in resected human appendix stimulated by noxious distending pressures. However, expression analysis of voltage-gated sodium channel α subunits revealed NaV 1.7 mRNA transcripts in nearly all retrogradely labelled colonic neurons, suggesting redundancy in function. By contrast, using comparative somatic behavioural models we identify that genetic deletion of NaV 1.7 (in NaV 1.8-expressing neurons) regulates noxious heat pain threshold and that this can be recapitulated by the selective NaV 1.7 antagonist PF-5198007. Our data demonstrate that NaV 1.7 (in NaV 1.8-expressing neurons) contributes to defined pain pathways in a modality-dependent manner, modulating somatic noxious heat pain, but is not required for visceral pain processing, and advocate that pharmacological block of NaV 1.7 alone in the viscera may be insufficient in targeting chronic visceral pain.
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Affiliation(s)
- James R F Hockley
- Neuroscience and Pain Research Unit, Pfizer Ltd., The Portway Building, Granta Science Park, Cambridge, CB21 6GS, UK
| | - Rafael González-Cano
- Department of Pharmacology, Biomedical Research Centre (CIBM) and Institute of Neuroscience, Faculty of Medicine, University of Granada, Granada, Spain
| | - Sheridan McMurray
- Neuroscience and Pain Research Unit, Pfizer Ltd., The Portway Building, Granta Science Park, Cambridge, CB21 6GS, UK
| | - Miguel A Tejada-Giraldez
- Department of Pharmacology, Biomedical Research Centre (CIBM) and Institute of Neuroscience, Faculty of Medicine, University of Granada, Granada, Spain
| | - Cian McGuire
- National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, E1 2AT, UK
| | - Antonio Torres
- Department of Biochemistry, Biomedical Research Centre (CIBM) and Institute of Neuroscience, Faculty of Medicine, University of Granada, Granada, Spain
| | - Anna L Wilbrey
- Neuroscience and Pain Research Unit, Pfizer Ltd., The Portway Building, Granta Science Park, Cambridge, CB21 6GS, UK
| | - Vincent Cibert-Goton
- National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, E1 2AT, UK
| | - Francisco R Nieto
- Department of Pharmacology, Biomedical Research Centre (CIBM) and Institute of Neuroscience, Faculty of Medicine, University of Granada, Granada, Spain
| | - Thomas Pitcher
- Neuroscience and Pain Research Unit, Pfizer Ltd., The Portway Building, Granta Science Park, Cambridge, CB21 6GS, UK
| | - Charles H Knowles
- National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, E1 2AT, UK
| | - José Manuel Baeyens
- Department of Pharmacology, Biomedical Research Centre (CIBM) and Institute of Neuroscience, Faculty of Medicine, University of Granada, Granada, Spain
| | - John N Wood
- Molecular Nociception Group, Department of Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Wendy J Winchester
- Neuroscience and Pain Research Unit, Pfizer Ltd., The Portway Building, Granta Science Park, Cambridge, CB21 6GS, UK
| | - David C Bulmer
- National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, E1 2AT, UK
| | - Cruz Miguel Cendán
- Department of Pharmacology, Biomedical Research Centre (CIBM) and Institute of Neuroscience, Faculty of Medicine, University of Granada, Granada, Spain
| | - Gordon McMurray
- Neuroscience and Pain Research Unit, Pfizer Ltd., The Portway Building, Granta Science Park, Cambridge, CB21 6GS, UK
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17
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Reed DE, Vanner SJ. Emerging studies of human visceral nociceptors. Am J Physiol Gastrointest Liver Physiol 2017; 312:G201-G207. [PMID: 28007748 DOI: 10.1152/ajpgi.00391.2016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 12/12/2016] [Accepted: 12/13/2016] [Indexed: 01/31/2023]
Abstract
Animal studies have led to significant advances in our understanding of pain mechanisms in the intestine that could lead to altered signaling in disorders such as irritable bowel syndrome. However, how these translate to the human afferent nervous system is unclear. Recent studies have demonstrated that it is possible to use a variety of techniques, including electrophysiological recordings, to begin to examine these concepts in humans. This mini-review examines these studies to explore how well animal studies translate to humans suffering from irritable bowel syndrome, highlights some of the advantages and technical limitations of these approaches, and identifies some priorities for future studies using human tissues.
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Affiliation(s)
- David E Reed
- Gastrointestinal Diseases Research Unit, Kingston General Hospital, Queen's University, Kingston, Ontario, Canada
| | - Stephen J Vanner
- Gastrointestinal Diseases Research Unit, Kingston General Hospital, Queen's University, Kingston, Ontario, Canada
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18
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Ng KS, Brookes SJ, Montes-Adrian NA, Mahns DA, Gladman MA. Electrophysiological characterization of human rectal afferents. Am J Physiol Gastrointest Liver Physiol 2016; 311:G1047-G1055. [PMID: 27789454 PMCID: PMC5298880 DOI: 10.1152/ajpgi.00153.2016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 10/17/2016] [Indexed: 01/31/2023]
Abstract
It is presumed that extrinsic afferent nerves link the rectum to the central nervous system. However, the anatomical/functional existence of such nerves has never previously been demonstrated in humans. Therefore, we aimed to identify and make electrophysiological recordings in vitro from extrinsic afferents, comparing human rectum to colon. Sections of normal rectum and colon were procured from anterior resection and right hemicolectomy specimens, respectively. Sections were pinned and extrinsic nerves dissected. Extracellular visceral afferent nerve activity was recorded. Neuronal responses to chemical [capsaicin and "inflammatory soup" (IS)] and mechanical (Von Frey probing) stimuli were recorded and quantified as peak firing rate (range) in 1-s intervals. Twenty-eight separate nerve trunks from eight rectums were studied. Of these, spontaneous multiunit afferent activity was recorded in 24 nerves. Peak firing rates increased significantly following capsaicin [median 6 (range 3-25) spikes/s vs. 2 (1-4), P < 0.001] and IS [median 5 (range 2-18) spikes/s vs. 2 (1-4), P < 0.001]. Mechanosensitive "hot spots" were identified in 16 nerves [median threshold 2.0 g (range 1.4-6.0 g)]. In eight of these, the threshold decreased after IS [1.0 g (0.4-1.4 g)]. By comparison, spontaneous activity was recorded in only 3/30 nerves studied from 10 colons, and only one hot spot (threshold 60 g) was identified. This study confirms the anatomical/functional existence of extrinsic rectal afferent nerves and characterizes their chemo- and mechanosensitivity for the first time in humans. They have different electrophysiological properties to colonic afferents and warrant further investigation in disease states.
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Affiliation(s)
- Kheng-Seong Ng
- 1Academic Colorectal Unit, Sydney Medical School, Concord, University of Sydney, Sydney, Australia; ,2Enteric Neuroscience and Gastrointestinal Research Group, ANZAC Research Institute, University of Sydney, Sydney, Australia;
| | - Simon J. Brookes
- 3Discipline of Human Physiology, FMST, School of Medicine, Flinders University, Adelaide, Australia; and
| | - Noemi A. Montes-Adrian
- 2Enteric Neuroscience and Gastrointestinal Research Group, ANZAC Research Institute, University of Sydney, Sydney, Australia;
| | - David A. Mahns
- 4Department of Integrative Physiology, School of Medicine, Western Sydney University, Sydney, Australia
| | - Marc A. Gladman
- 1Academic Colorectal Unit, Sydney Medical School, Concord, University of Sydney, Sydney, Australia; ,2Enteric Neuroscience and Gastrointestinal Research Group, ANZAC Research Institute, University of Sydney, Sydney, Australia;
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19
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Nullens S, Deiteren A, Jiang W, Keating C, Ceuleers H, Francque S, Grundy D, De Man JG, De Winter BY. In Vitro Recording of Mesenteric Afferent Nerve Activity in Mouse Jejunal and Colonic Segments. J Vis Exp 2016. [PMID: 27805592 DOI: 10.3791/54576] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Afferent nerves not only convey information concerning normal physiology, but also signal disturbed homeostasis and pathophysiological processes of the different organ systems from the periphery towards the central nervous system. As such, the increased activity or 'sensitization' of mesenteric afferent nerves has been allocated an important role in the pathophysiology of visceral hypersensitivity and abdominal pain syndromes. Mesenteric afferent nerve activity can be measured in vitro in an isolated intestinal segment that is mounted in a purpose-built organ bath and from which the splanchnic nerve is isolated, allowing researchers to directly assess nerve activity adjacent to the gastrointestinal segment. Activity can be recorded at baseline in standardized conditions, during distension of the segment or following the addition of pharmacological compounds delivered intraluminally or serosally. This technique allows the researcher to easily study the effect of drugs targeting the peripheral nervous system in control specimens; besides, it provides crucial information on how neuronal activity is altered during disease. It should be noted however that measuring afferent neuronal firing activity only constitutes one relay station in the complex neuronal signaling cascade, and researchers should bear in mind not to overlook neuronal activity at other levels (e.g., dorsal root ganglia, spinal cord or central nervous system) in order to fully elucidate the complex neuronal physiology in health and disease. Commonly used applications include the study of neuronal activity in response to the administration of lipopolysaccharide, and the study of afferent nerve activity in animal models of irritable bowel syndrome. In a more translational approach, the isolated mouse intestinal segment can be exposed to colonic supernatants from IBS patients. Furthermore, a modification of this technique has been recently shown to be applicable in human colonic specimens.
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Affiliation(s)
- Sara Nullens
- Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp
| | - Annemie Deiteren
- Visceral Pain Group, Discipline of Medicine, University of Adelaide
| | - Wen Jiang
- Department of Biomedical Sciences, University of Sheffield
| | - Christopher Keating
- Department of Pharmacy, Pharmacology and Postgraduate Medicine, University of Hertfordshire
| | - Hannah Ceuleers
- Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp
| | - Sven Francque
- Department of Gastroenterology and Hepatology, Antwerp University Hospital
| | - David Grundy
- Department of Biomedical Sciences, University of Sheffield
| | - Joris G De Man
- Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp
| | - Benedicte Y De Winter
- Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp;
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21
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Abstract
Activation of visceral nociceptors by inflammatory mediators contributes to visceral hypersensitivity and abdominal pain associated with many gastrointestinal disorders. Purine and pyrimidine nucleotides (e.g., ATP and UTP) are strongly implicated in this process following their release from epithelial cells during mechanical stimulation of the gut, and from immune cells during inflammation. Actions of ATP are mediated through both ionotropic P2X receptors and metabotropic P2Y receptors. P2X receptor activation causes excitation of visceral afferents; however, the impact of P2Y receptor activation on visceral afferents innervating the gut is unclear. Here we investigate the effects of stimulating P2Y receptors in isolated mouse colonic sensory neurons, and visceral nociceptor fibers in mouse and human nerve-gut preparations. Additionally, we investigate the role of Nav1.9 in mediating murine responses. The application of UTP (P2Y2 and P2Y4 agonist) sensitized colonic sensory neurons by increasing action potential firing to current injection and depolarizing the membrane potential. The application of ADP (P2Y1, P2Y12, and P2Y13 agonist) also increased action potential firing, an effect blocked by the selective P2Y1 receptor antagonist MRS2500. UTP or ADP stimulated afferents, including mouse and human visceral nociceptors, in nerve-gut preparations. P2Y1 and P2Y2 transcripts were detected in 80% and 56% of retrogradely labeled colonic neurons, respectively. Nav1.9 transcripts colocalized in 86% of P2Y1-positive and 100% of P2Y2-positive colonic neurons, consistent with reduced afferent fiber responses to UTP and ADP in Na(v)1.9(-/-) mice. These data demonstrate that P2Y receptor activation stimulates mouse and human visceral nociceptors, highlighting P2Y-dependent mechanisms in the generation of visceral pain during gastrointestinal disease.
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22
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Zhang L, Song J, Hou X. Mast Cells and Irritable Bowel Syndrome: From the Bench to the Bedside. J Neurogastroenterol Motil 2016; 22:181-92. [PMID: 26755686 PMCID: PMC4819856 DOI: 10.5056/jnm15137] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 12/07/2015] [Accepted: 12/26/2015] [Indexed: 12/11/2022] Open
Abstract
Irritable bowel syndrome (IBS) is traditionally defined as a functional disorder since it lacks demonstrable pathological abnormalities. However, in recent years, low grade inflammatory infiltration, often rich in mast cells, in both the small and large bowel, has been observed in some patients with IBS. The close association of mast cells with major intestinal functions, such as epithelial secretion and permeability, neuroimmune interactions, visceral sensation, and peristalsis, makes researchers and gastroenterologists to focus attention on the key roles of mast cells in the pathogenesis of IBS. Numerous studies have been carried out to identify the mechanisms in the development, infiltration, activation, and degranulation of intestinal mast cells, as well as the actions of mast cells in the processes of mucosal barrier disruption, mucosal immune dysregulation, visceral hypersensitivity, dysmotility, and local and central stress in IBS. Moreover, therapies targeting mast cells, such as mast cell stabilizers (cromoglycate and ketotifen) and antagonists of histamine and serotonin receptors, have been tried in IBS patients, and have partially exhibited considerable efficacy. This review focuses on recent advances in the role of mast cells in IBS, with particular emphasis on bridging experimental data with clinical therapeutics for IBS patients.
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Affiliation(s)
- Lei Zhang
- Division of Gastroenterology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jun Song
- Division of Gastroenterology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaohua Hou
- Division of Gastroenterology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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23
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Matsumoto K, Kato S, Horie S. [Transient receptor potential cation channels in visceral pain]. Nihon Yakurigaku Zasshi 2015; 146:233-5. [PMID: 26656968 DOI: 10.1254/fpj.146.233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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24
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Deiteren A, De Man JG, Keating C, Jiang W, De Schepper HU, Pelckmans PA, Francque SM, De Winter BY. Mechanisms contributing to visceral hypersensitivity: focus on splanchnic afferent nerve signaling. Neurogastroenterol Motil 2015; 27:1709-20. [PMID: 26337498 DOI: 10.1111/nmo.12667] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 08/04/2015] [Indexed: 12/24/2022]
Abstract
BACKGROUND Visceral hypersensitivity is a main characteristic of functional bowel disorders and is mediated by both peripheral and central factors. We investigated whether enhanced splanchnic afferent signaling in vitro is associated with visceral hypersensitivity in vivo in an acute and postinflammatory rat model of colitis. METHODS Trinitrobenzene sulfonic acid (TNBS)-colitis was monitored individually by colonoscopy to confirm colitis and follow convalescence and endoscopic healing in each rat. Experiments were performed in controls, rats with acute colitis and in postcolitis rats. Colonic afferent mechanosensitivity was assessed in vivo by quantifying visceromotor responses (VMRs), and by making extracellular afferent recordings from splanchnic nerve bundles in vitro. Multiunit afferent activity was classified into single units identified as low threshold (LT), wide dynamic range (WDR), high threshold (HT), and mechanically insensitive afferents (MIA). KEY RESULTS During acute TNBS-colitis, VMRs were significantly increased and splanchnic nerve recordings showed proportionally less MIA and increased WDR and HT afferents. Acute colitis gave rise to an enhanced spontaneous activity of both LT and MIA and augmented afferent mechanosensitivity in LT, WDR and HT afferents. Postcolitis, VMRs remained significantly increased, whereas splanchnic nerve recordings showed that the proportion of LT, WDR, HT and MIA had normalized to control values. However, LT and MIA continued to show increased spontaneous activity and WDR and HT remained sensitized to colorectal distension. CONCLUSIONS & INFERENCES Visceral hypersensitivity in vivo is associated with sensitized splanchnic afferent responses both during acute colitis and in the postinflammatory phase. However, splanchnic afferent subpopulations are affected differentially at both time points.
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Affiliation(s)
- A Deiteren
- Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp, Antwerp, Belgium
| | - J G De Man
- Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp, Antwerp, Belgium
| | - C Keating
- Department of Biomedical Sciences, University of Sheffield, Sheffield, UK
| | - W Jiang
- Department of Biomedical Sciences, University of Sheffield, Sheffield, UK
| | - H U De Schepper
- Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp, Antwerp, Belgium
- Department of Gastroenterology and Hepatology, Antwerp University Hospital, Antwerp, Belgium
| | - P A Pelckmans
- Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp, Antwerp, Belgium
- Department of Gastroenterology and Hepatology, Antwerp University Hospital, Antwerp, Belgium
| | - S M Francque
- Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp, Antwerp, Belgium
- Department of Gastroenterology and Hepatology, Antwerp University Hospital, Antwerp, Belgium
| | - B Y De Winter
- Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp, Antwerp, Belgium
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25
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Blackshaw LA. Transient receptor potential cation channels in visceral sensory pathways. Br J Pharmacol 2014; 171:2528-36. [PMID: 24641218 DOI: 10.1111/bph.12641] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 01/09/2014] [Accepted: 01/20/2014] [Indexed: 01/03/2023] Open
Abstract
The extensive literature on this subject is in direct contrast to the limited range of clinical uses for ligands of the transient receptor potential cation channels (TRPs) in diseases of the viscera. TRPV1 is the most spectacular example of this imbalance, as it is in other systems, but it is nonetheless the only TRP target that is currently targeted clinically in bladder sensory dysfunction. It is not clear why this discrepancy exists, but a likely answer is in the promiscuity of TRPs as sensors and transducers for environmental mechanical and chemical stimuli. This review first describes the different sensory pathways from the viscera, and on which nociceptive and non-nociceptive neurones within these pathways TRPs are expressed. They not only fulfil roles as both mechano- and chemo-sensors on visceral afferents, but also form an effector mechanism for cell activation after activation of GPCR and cytokine receptors. Their role may be markedly changed in diseased states, including chronic pain and inflammation. Pain presents the most obvious potential for further development of therapeutic interventions targeted at TRPs, but forms of inflammation are emerging as likely to benefit also. However, despite much basic research, we are still at the beginning of exploring such potential in visceral sensory pathways.
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Affiliation(s)
- L Ashley Blackshaw
- Wingate Institute for Neurogastroenterology, Centre for Digestive Diseases, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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Sanger GJ, Broad J, Kung V, Knowles CH. Translational neuropharmacology: the use of human isolated gastrointestinal tissues. Br J Pharmacol 2014; 168:28-43. [PMID: 22946540 DOI: 10.1111/j.1476-5381.2012.02198.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 08/08/2012] [Accepted: 08/23/2012] [Indexed: 12/22/2022] Open
Abstract
Translational sciences increasingly emphasize the measurement of functions in native human tissues. However, such studies must confront variations in patient age, gender, genetic background and disease. Here, these are discussed with reference to neuromuscular and neurosecretory functions of the human gastrointestinal (GI) tract. Tissues are obtained after informed consent, in collaboration with surgeons (surgical techniques help minimize variables) and pathologists. Given the difficulties of directly recording from human myenteric neurones (embedded between muscle layers), enteric motor nerve functions are studied by measuring muscle contractions/relaxations evoked by electrical stimulation of intrinsic nerves; responses are regionally dependent, often involving cholinergic and nitrergic phenotypes. Enteric sensory functions can be studied by evoking the peristaltic reflex, involving enteric sensory and motor nerves, but this has rarely been achieved. As submucosal neurones are more accessible (after removing the mucosa), direct neuronal recordings are possible. Neurosecretory functions are studied by measuring changes in short-circuit current across the mucosa. For all experiments, basic questions must be addressed. Because tissues are from patients, what are the controls and the influence of disease? How long does it take before function fully recovers? What is the impact of age- and gender-related differences? What is the optimal sample size? Addressing these and other questions minimizes variability and raises the scientific credibility of human tissue research. Such studies also reduce animal use. Further, the many differences between animal and human GI functions also means that human tissue research must question the ethical validity of using strains of animals with unproved translational significance.
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Affiliation(s)
- G J Sanger
- Neurogastroenterology Group, Blizard Institute, Barts & The London School of Medicine and Dentistry, Queen Mary University of London, UK.
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Immune activation in irritable bowel syndrome: can neuroimmune interactions explain symptoms? Am J Gastroenterol 2013; 108:1066-74. [PMID: 23649183 DOI: 10.1038/ajg.2013.120] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 03/26/2013] [Indexed: 02/06/2023]
Abstract
Irritable bowel syndrome (IBS) is a functional disorder of the gastrointestinal (GI) tract characterized by pain or discomfort from the lower abdominal region, which is associated with altered bowel habit. Despite its prevalence, there is currently a lack of effective treatment options for patients. IBS has long been considered as a neurological condition resulting from alterations in the brain gut axis, but immunological alterations are increasingly reported in IBS patients, consistent with the hypothesis that there is a chronic, but low-grade, immune activation. Mediators released by immune cells act to either dampen or amplify the activity of GI nerves. Release of a number of these mediators correlates with symptoms of IBS, highlighting the importance of interactions between the immune and the nervous systems. Investigation of the role of microbiota in these interactions is in its early stages, but may provide many answers regarding the mechanisms underlying activation of the immune system in IBS. Identifying what the key changes in the GI immune system are in IBS and how these changes modulate viscerosensory nervous function is essential for the development of novel therapies for the underlying disorder.
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Abstract
Visceral sensory neurons activate reflex pathways that control gut function and also give rise to important sensations, such as fullness, bloating, nausea, discomfort, urgency and pain. Sensory neurons are organised into three distinct anatomical pathways to the central nervous system (vagal, thoracolumbar and lumbosacral). Although remarkable progress has been made in characterizing the roles of many ion channels, receptors and second messengers in visceral sensory neurons, the basic aim of understanding how many classes there are, and how they differ, has proven difficult to achieve. We suggest that just five structurally distinct types of sensory endings are present in the gut wall that account for essentially all of the primary afferent neurons in the three pathways. Each of these five major structural types of endings seems to show distinctive combinations of physiological responses. These types are: 'intraganglionic laminar' endings in myenteric ganglia; 'mucosal' endings located in the subepithelial layer; 'muscular-mucosal' afferents, with mechanosensitive endings close to the muscularis mucosae; 'intramuscular' endings, with endings within the smooth muscle layers; and 'vascular' afferents, with sensitive endings primarily on blood vessels. 'Silent' afferents might be a subset of inexcitable 'vascular' afferents, which can be switched on by inflammatory mediators. Extrinsic sensory neurons comprise an attractive focus for targeted therapeutic intervention in a range of gastrointestinal disorders.
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SCHEMANN MICHAEL, CAMILLERI MICHAEL. Functions and imaging of mast cell and neural axis of the gut. Gastroenterology 2013; 144:698-704.e4. [PMID: 23354018 PMCID: PMC3922647 DOI: 10.1053/j.gastro.2013.01.040] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 12/05/2012] [Accepted: 01/23/2013] [Indexed: 12/22/2022]
Abstract
Close association between nerves and mast cells in the gut wall provides the microanatomic basis for functional interactions between these elements, supporting the hypothesis that a mast cell-nerve axis influences gut functions in health and disease. Advanced morphology and imaging techniques are now available to assess structural and functional relationships of the mast cell-nerve axis in human gut tissues. Morphologic techniques including co-labeling of mast cells and nerves serve to evaluate changes in their densities and anatomic proximity. Calcium (Ca(++)) and potentiometric dye imaging provide novel insights into functions such as mast cell-nerve signaling in the human gut tissues. Such imaging promises to reveal new ionic or molecular targets to normalize nerve sensitization induced by mast cell hyperactivity or mast cell sensitization by neurogenic inflammatory pathways. These targets include proteinase-activated receptor (PAR) 1 or histamine receptors. In patients, optical imaging in the gut in vivo has the potential to identify neural structures and inflammation in vivo. The latter has some risks and potential of sampling error with a single biopsy. Techniques that image nerve fibers in the retina without the need for contrast agents (optical coherence tomography and full-field optical coherence microscopy) may be applied to study submucous neural plexus. Moreover, the combination of submucosal dissection, use of a fluorescent marker, and endoscopic confocal microscopy provides detailed imaging of myenteric neurons and smooth muscle cells in the muscularis propria. Studies of motility and functional gastrointestinal disorders would be feasible without the need for full-thickness biopsy.
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Affiliation(s)
- MICHAEL SCHEMANN
- Human Biology, Technische Universität
München, Freising, Germany
| | - MICHAEL CAMILLERI
- Clinical Enteric Neuroscience Translational and
Epidemiological Research (CENTER), Mayo Clinic, Rochester, Minnesota
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O'Neill J, Brock C, Olesen AE, Andresen T, Nilsson M, Dickenson AH. Unravelling the mystery of capsaicin: a tool to understand and treat pain. Pharmacol Rev 2013; 64:939-71. [PMID: 23023032 DOI: 10.1124/pr.112.006163] [Citation(s) in RCA: 220] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
A large number of pharmacological studies have used capsaicin as a tool to activate many physiological systems, with an emphasis on pain research but also including functions such as the cardiovascular system, the respiratory system, and the urinary tract. Understanding the actions of capsaicin led to the discovery its receptor, transient receptor potential (TRP) vanilloid subfamily member 1 (TRPV1), part of the superfamily of TRP receptors, sensing external events. This receptor is found on key fine sensory afferents, and so the use of capsaicin to selectively activate pain afferents has been exploited in animal studies, human psychophysics, and imaging studies. Its effects depend on the dose and route of administration and may include sensitization, desensitization, withdrawal of afferent nerve terminals, or even overt death of afferent fibers. The ability of capsaicin to generate central hypersensitivity has been valuable in understanding the consequences and mechanisms behind enhanced central processing of pain. In addition, capsaicin has been used as a therapeutic agent when applied topically, and antagonists of the TRPV1 receptor have been developed. Overall, the numerous uses for capsaicin are clear; hence, the rationale of this review is to bring together and discuss the different types of studies that exploit these actions to shed light upon capsaicin working both as a tool to understand pain but also as a treatment for chronic pain. This review will discuss the various actions of capsaicin and how it lends itself to these different purposes.
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Affiliation(s)
- Jessica O'Neill
- Neuroscience, Physiology and Pharmacology, University College London, London.
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31
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Perez-Burgos A, Wang B, Mao YK, Mistry B, McVey Neufeld KA, Bienenstock J, Kunze W. Psychoactive bacteria Lactobacillus rhamnosus (JB-1) elicits rapid frequency facilitation in vagal afferents. Am J Physiol Gastrointest Liver Physiol 2013; 304:G211-20. [PMID: 23139216 DOI: 10.1152/ajpgi.00128.2012] [Citation(s) in RCA: 150] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Mounting evidence supports the influence of the gut microbiome on the local enteric nervous system and its effects on brain chemistry and relevant behavior. Vagal afferents are involved in some of these effects. We previously showed that ingestion of the probiotic bacterium Lactobacillus rhamnosus (JB-1) caused extensive neurochemical changes in the brain and behavior that were abrogated by prior vagotomy. Because information can be transmitted to the brain via primary afferents encoded as neuronal spike trains, our goal was to record those induced by JB-1 in vagal afferents in the mesenteric nerve bundle and thus determine the nature of the signals sent to the brain. Male Swiss Webster mice jejunal segments were cannulated ex vivo, and serosal and luminal compartments were perfused separately. Bacteria were added intraluminally. We found no evidence for translocation of labeled bacteria across the epithelium during the experiment. We recorded extracellular multi- and single-unit neuronal activity with glass suction pipettes. Within minutes of application, JB-1 increased the constitutive single- and multiunit firing rate of the mesenteric nerve bundle, but Lactobacillus salivarius (a negative control) or media alone were ineffective. JB-1 significantly augmented multiunit discharge responses to an intraluminal distension pressure of 31 hPa. Prior subdiaphragmatic vagotomy abolished all of the JB-1-evoked effects. This detailed exploration of the neuronal spike firing that encodes behavioral signaling to the brain may be useful to identify effective psychoactive bacteria and thereby offer an alternative new perspective in the field of psychiatry and comorbid conditions.
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Affiliation(s)
- Azucena Perez-Burgos
- McMaster Brain-Body Institute, St. Joseph's Healthcare, Hamilton, Ontario, Canada.
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Bassan MS, Holt B, Moss A, Williams SJ, Sonson R, Bourke MJ. Carbon dioxide insufflation reduces number of postprocedure admissions after endoscopic resection of large colonic lesions: a prospective cohort study. Gastrointest Endosc 2013; 77:90-5. [PMID: 22867448 DOI: 10.1016/j.gie.2012.06.004] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Accepted: 06/06/2012] [Indexed: 02/08/2023]
Abstract
BACKGROUND Endoscopic resection (ER) for large colonic lesions is a safe and effective outpatient treatment. Postprocedural pain creates concern for perforation and often results in postprocedure admission (PPA). Carbon dioxide (CO(2)) insufflation has been shown to reduce pain scores after routine colonoscopy, but an influence on more critical outcomes such as PPA has not been shown. OBJECTIVE To assess the outcomes of patients undergoing ER for large colonic lesions, comparing those having air versus those having CO(2) insufflation. DESIGN Prospective, observational, cohort study. SETTING Academic, high-volume, tertiary-care referral center. PATIENTS Consecutive patients referred for ER of sessile colorectal polyps ≥20 mm. INTERVENTION ER with air or CO(2). MAIN OUTCOME MEASUREMENTS Rates of PPA, technical outcomes, complication rates. RESULTS ER was performed on 575 lesions ≥20 mm, 228 with CO(2) insufflation. Mean lesion size was 36.5 mm. Lesion and patient characteristics were similar in both groups. The use of CO(2) was associated with a 62% decrease in the PPA rate from 8.9% to 3.4% (P = .01). This was mainly because of an 82% decrease in PPA for pain from 5.7% to 1.0% (P = .006). There were no significant difference in the rates of complications. Multiple logistical regression was performed. The adjusted odds ratio (OR) of PPA (OR 0.39; 95% confidence interval [CI], 0.16-0.95; P = .04) and PPA for pain (OR 0.18; 95% CI, 0.04-0.78; P = .02) in the CO(2) group remained significant. LIMITATIONS Single center, nonrandomized study. CONCLUSION CO(2) insufflation significantly reduces PPA after ER of large colonic lesions, primarily because of reduced PPA for pain. CO(2) insufflation should be routinely used during ER of large colonic lesions.
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Affiliation(s)
- Milan S Bassan
- Department of Gastroenterology and Hepatology, Westmead Hospital, Sydney, New South Wales, Australia
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Iturrino J, Camilleri M, Busciglio I, Burton D, Zinsmeister AR. Sensations of gas and pain and their relationship with compliance during distension in human colon. Neurogastroenterol Motil 2012; 24:646-51, e275. [PMID: 22393902 PMCID: PMC3374900 DOI: 10.1111/j.1365-2982.2012.01901.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND Colonic mechanosensory afferents 'in parallel' to circular muscle activate prevertebral ganglion reflexes; 'in series', afferents convey visceral sensation to the central nervous system; and pain receptors are activated with muscle distension. Our aim was to analyze the relationships of gas and pain sensations during graded distensions, and the association of sensations with colonic compliance in conscious humans. METHODS The data were acquired in a prior study performed on 60 healthy volunteers (aged 18-75 years) under baseline conditions. Colonic compliance was measured in response to 4 mmHg stepwise balloon distensions to estimate pressure at half-maximum volume (Pr(50%)). Sensation ratings for gas and pain were averaged over distensions at 16, 24, 30 and 36 mmHg above baseline operating pressure. Associations between mean gas and pain ratings, and colonic compliance were assessed with Pearson correlations. KEY RESULTS Gas and pain sensations were significantly correlated at all levels of distension (all P < 0.001). Significant inverse correlations between Pr(50%) and sensations of gas and pain were observed, suggesting that lower compliance was associated with lower sensations. Up to 25% of the variance in sensation may be attributed to colonic compliance. CONCLUSIONS & INFERENCES These data are consistent with the hypothesis that, if circumferential colonic receptors are stimulated by distension to mediate gas and pain in humans, they are, at least partly, arranged 'in parallel' to the muscle layer.
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Affiliation(s)
- Johanna Iturrino
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER), College of Medicine, Mayo Clinic, Rochester, MN
- Division of Gastroenterology and Hepatology, College of Medicine, Mayo Clinic, Rochester, MN
| | - Michael Camilleri
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER), College of Medicine, Mayo Clinic, Rochester, MN
- Division of Gastroenterology and Hepatology, College of Medicine, Mayo Clinic, Rochester, MN
- Department of Physiology and Biomedical Engineering, College of Medicine, Mayo Clinic, Rochester, MN
| | - Irene Busciglio
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER), College of Medicine, Mayo Clinic, Rochester, MN
| | - Duane Burton
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER), College of Medicine, Mayo Clinic, Rochester, MN
| | - Alan R. Zinsmeister
- Department of Health Sciences Research, Division of Biomedical Statistics and Informatics, College of Medicine, Mayo Clinic, Rochester, MN
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Keszthelyi D, Troost F, Simrén M, Ludidi S, Kruimel J, Conchillo J, Masclee A. Revisiting concepts of visceral nociception in irritable bowel syndrome. Eur J Pain 2012; 16:1444-54. [DOI: 10.1002/j.1532-2149.2012.00147.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/20/2012] [Indexed: 12/12/2022]
Affiliation(s)
| | | | - M. Simrén
- Department of Internal Medicine; Institute of Medicine Sahlgrenska Academy; University of Gothenburg; Sweden
| | - S. Ludidi
- Division of Gastroenterology-Hepatology; Department of Internal Medicine; Maastricht University Medical Center; The Netherlands
| | - J.W. Kruimel
- Division of Gastroenterology-Hepatology; Department of Internal Medicine; Maastricht University Medical Center; The Netherlands
| | - J.M. Conchillo
- Division of Gastroenterology-Hepatology; Department of Internal Medicine; Maastricht University Medical Center; The Netherlands
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Current World Literature. Curr Opin Support Palliat Care 2012; 6:109-25. [DOI: 10.1097/spc.0b013e328350f70c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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36
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Mast cell–nerve axis with a focus on the human gut. Biochim Biophys Acta Mol Basis Dis 2012; 1822:85-92. [DOI: 10.1016/j.bbadis.2011.06.004] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 06/07/2011] [Accepted: 06/10/2011] [Indexed: 02/07/2023]
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Achieving translation in models of visceral pain. Curr Opin Pharmacol 2011; 11:575-81. [PMID: 22000605 DOI: 10.1016/j.coph.2011.09.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Accepted: 09/23/2011] [Indexed: 02/08/2023]
Abstract
The failure of drugs to modify pain end points in clinical trials for irritable bowel syndrome (IBS) highlights the knowledge gap that exists in the translation of efficacy in animal models of visceral pain into the clinic. Recent progress has been made towards improving the translation of visceral pain, particularly with regard to the activation of the sensory nerves which relay pain from the gut to the brain. This review will focus on studies which have identified the presence of an altered gastrointestinal and immune environment in IBS patients. The development of human gastrointestinal visceral afferent recordings has allowed direct comparison between sensory nerve studies in animals and human, as well as important advances in our understanding of the ion channels that underpin the changes in sensory nerve excitability.
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