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Buhner S, Schäuffele S, Giesbertz P, Demir IE, Zeller F, Traidl-Hoffmann C, Schemann M, Gilles S. Allergen-free extracts from birch, ragweed, and hazel pollen activate human and guinea-pig submucous and spinal sensory neurons. Neurogastroenterol Motil 2023:e14559. [PMID: 36989179 DOI: 10.1111/nmo.14559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 01/16/2023] [Accepted: 02/24/2023] [Indexed: 03/30/2023]
Abstract
BACKGROUND Non-allergenic, low molecular weight components of pollen grains are suspected to trigger changes in gut functions, sometimes leading to inflammatory conditions. Based on extensive neuroimmune communication in the gut wall, we investigated the effects of aqueous pollen extracts (APE) on enteric and spinal sensory neurons. METHODS Using Ca2+ and fast potentiometric imaging, we recorded the responses of guinea-pig and human submucous and guinea-pig dorsal root ganglion (DRG) neurons to microejection of low (<3 kDa) and high (≥3 kDa) molecular weight APEs of birch, ragweed, and hazel. Histamine was determined pharmacologically and by mass spectrometry (LC-MS/MS). KEY RESULTS Birch APE<3kDa evoked strong [Ca+2 ]i signals in the vast majority of guinea-pig DRG neurons, and in guinea-pig and human enteric neurons. The effect of birch APE≥3kDa was much weaker. Fast neuroimaging in human enteric neurons revealed an instantaneous spike discharge after microejection of birch, ragweed, and hazel APE<3kDa [median (interquartile range) at 7.0 Hz (6.2/9.8), 5.7 Hz (4.4/7.1), and 8.4 Hz (4.3/12.5), respectively]. The percentage of responding neurons per ganglion were similar [birch 40.0% (33.3/100.0), ragweed 50.8% (34.4/85.6), and hazel 83.3% (57.1/100.0)]. A mixture of histamine receptor (H1-H3) blockers significantly reduced nerve activation evoked by birch and ragweed APEs<3kDa , but was ineffective on hazel. Histamine concentrations in ragweed, birch and hazel APE's < 3 kDa were 0.764, 0.047, and 0.013 μM, respectively. CONCLUSIONS Allergen-free APEs from birch, ragweed, and hazel evoked strong nerve activation. Altered nerve-immune signaling as a result of severe pollen exposure could be a pathophysiological feature of allergic and non-allergic gut inflammation.
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Affiliation(s)
- Sabine Buhner
- Chair of Human Biology, Technical University Munich, Freising, Germany
| | | | - Pieter Giesbertz
- Molecular Nutrition Unit, Technical University Munich, Freising, Germany
| | - Ihsan Ekin Demir
- University Hospital Rechts der Isar, Technical University Munich, Munich, Germany
| | - Florian Zeller
- Department of Surgery, Academic Hospital Freising, Freising, Germany
| | - Claudia Traidl-Hoffmann
- Environmental Medicine, Faculty of Medicine, University of Augsburg, Augsburg, Germany
- Institute of Environmental Medicine, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Christine Kühne Center for Allergy Research and Education (CK-Care), Davos, Switzerland
| | - Michael Schemann
- Chair of Human Biology, Technical University Munich, Freising, Germany
| | - Stefanie Gilles
- Environmental Medicine, Faculty of Medicine, University of Augsburg, Augsburg, Germany
- Institute of Environmental Medicine, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
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Kollmann P, Elfers K, Maurer S, Klingenspor M, Schemann M, Mazzuoli-Weber G. Submucosal enteric neurons of the cavine distal colon are sensitive to hypoosmolar stimuli. J Physiol 2020; 598:5317-5332. [PMID: 32880976 DOI: 10.1113/jp280309] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 08/24/2020] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Neurons of the enteric submucous plexus are challenged by osmolar fluctuations during digestion and absorption of nutrients. Central neurons are very sensitive to changes in osmolality but knowledge on that issue related to enteric neurons is sparse. The present study focuses on investigation of osmosensitivity of submucosal neurons including potential molecular mediating mechanisms. Results show that submucosal neurons respond to hypoosmolar stimuli with increased activity which is partially mediated by the transient receptor potential vanilloid 4 channel. We provided important information on osmosensitive properties of enteric neurons. These data are fundamental to better explain the nerve-mediated control of the gastrointestinal functions during physiological and pathophysiological (diarrhoea) conditions. ABSTRACT Enteric neurons are located inside the gut wall, where they are confronted with changes in osmolality during (inter-) digestive periods. In particular, neurons of the submucous plexus (SMP), located between epithelial cells and blood vessels may sense and respond to osmotic shifts. The present study was conducted to investigate osmosensitivity of enteric submucosal neurons and the potential role of the transient receptor potential vanilloid 4 channel (TRPV4) as a mediator of enteric neuronal osmosensitivity. Therefore, freshly dissected submucosal preparations from guinea pig colon were investigated for osmosensitivity using voltage-sensitive dye and Ca2+ imaging. Acute hypoosmolar stimuli (final osmolality reached at ganglia of 94, 144 and 194 mOsm kg-1 ) were applied to single ganglia using a local perfusion system. Expression of TRPV4 in the SMP was quantified using qRT-PCR, and GSK1016790A and HC-067047 were used to activate or block the receptor, respectively, revealing its relevance in enteric osmosensitivity. On average, 11.0 [7.0/17.0] % of submucosal neurons per ganglion responded to the hypoosmolar stimulus. The Ca2+ imaging experiments showed that glia responded to the hypoosmolar stimulus, but with a delay in comparison with neurons. mRNA expression of TRPV4 could be shown in the SMP and blockade of the receptor by HC-067047 significantly decreased the number of responding neurons (0.0 [0.0/6.3] %) while the TRPV4 agonist GSK1016790A caused action potential discharge in a subpopulation of osmosensitive enteric neurons. The results of the present study provide insight into the osmosensitivity of submucosal enteric neurons and strongly indicate the involvement of TRPV4 as an osmotransducer.
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Affiliation(s)
- Patrick Kollmann
- Chair of Human Biology, Technical University of Munich, Freising, Germany
| | - Kristin Elfers
- Institute for Physiology and Cell Biology, University of Veterinary Medicine, Foundation, Hannover, Germany
| | - Stefanie Maurer
- Chair of Molecular Nutritional Medicine, Else Kröner-Fresenius Center for Nutritional Medicine & ZIEL Institute for Food & Health, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Martin Klingenspor
- Chair of Molecular Nutritional Medicine, Else Kröner-Fresenius Center for Nutritional Medicine & ZIEL Institute for Food & Health, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Michael Schemann
- Chair of Human Biology, Technical University of Munich, Freising, Germany
| | - Gemma Mazzuoli-Weber
- Institute for Physiology and Cell Biology, University of Veterinary Medicine, Foundation, Hannover, Germany
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3
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Compression and stretch sensitive submucosal neurons of the porcine and human colon. Sci Rep 2020; 10:13791. [PMID: 32796868 PMCID: PMC7428018 DOI: 10.1038/s41598-020-70216-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 07/24/2020] [Indexed: 01/28/2023] Open
Abstract
The pig is commonly believed to be a relevant model for human gut functions-however, there are only a few comparative studies and none on neural control mechanisms. To address this lack we identified as one central aspect mechanosensitive enteric neurons (MEN) in porcine and human colon. We used neuroimaging techniques to record responses to tensile or compressive forces in submucous neurons. Compression and stretch caused Ca-transients and immediate spike discharge in 5-11% of porcine and 15-24% of human enteric neurons. The majority of these MEN exclusively responded to either stimulus quality but about 9% responded to both. Most of the MEN expressed choline acetyltransferase and substance P; nitric oxide synthase-positive MEN primarily occurred in distal colon. The findings reveal common features of MEN in human and pig colon which we interpret as a result of species-independent evolutionary conservation rather than a specific functional proximity between the two species.
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4
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Minoshima W, Hosokawa C, Kudoh SN, Tawa K. Real-time fluorescence measurement of spontaneous activity in a high-density hippocampal network cultivated on a plasmonic dish. J Chem Phys 2020; 152:014706. [PMID: 31914750 DOI: 10.1063/1.5131497] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
High-density cultured neuronal networks have been used to evaluate synchronized features of neuronal populations. Voltage-sensitive dye (VSD) imaging of a dissociated cultured neuronal network is a critical method for studying synchronized neuronal activity in single cells. However, the signals of VSD are generally too faint-that is, the signal-to-noise ratio (S/N) is too low-to detect neuronal activity. In our previous research, a silver (Ag) plasmonic chip enhanced the fluorescence intensity of VSD to detect spontaneous neural spikes on VSD imaging. However, no high-density network was cultivated on the Ag plasmonic chip, perhaps because of the chemical instability of the Ag surface. In this study, to overcome the instability of the chip, we used a chemically stable gold (Au) plasmonic dish, which was a plastic dish with a plasmonic chip pasted to the bottom, to observe neuronal activity in a high-density neuronal network. We expected that the S/N in real-time VSD imaging of the Au plasmonic chip would be improved compared to that of a conventional glass-bottomed dish, and we also expected to detect frequent neural spikes. The increase in the number of spikes when inhibitory neurotransmitter receptors were inhibited suggests that the spikes corresponded to neural activity. Therefore, real-time VSD imaging of an Au plasmonic dish was effective for measuring spontaneous network activity in a high-density neuronal network at the spatial resolution of a single cell.
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Affiliation(s)
- Wataru Minoshima
- School of Science and Technology, Kwansei Gakuin University, Hyogo, Japan
| | - Chie Hosokawa
- School of Science and Technology, Kwansei Gakuin University, Hyogo, Japan
| | - Suguru N Kudoh
- School of Science and Technology, Kwansei Gakuin University, Hyogo, Japan
| | - Keiko Tawa
- School of Science and Technology, Kwansei Gakuin University, Hyogo, Japan
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5
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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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6
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Piezo proteins: incidence and abundance in the enteric nervous system. Is there a link with mechanosensitivity? Cell Tissue Res 2018; 375:605-618. [PMID: 30324494 DOI: 10.1007/s00441-018-2926-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 09/10/2018] [Indexed: 10/28/2022]
Abstract
Piezo channels play fundamental roles in many physiological processes. Their presence and functional role in the enteric nervous system is still not known. We hypothesize that they play a role in mechanotransduction in enteric neurons. Our aims are to quantify the presence of both Piezo1 and 2 in enteric neurons throughout the gastrointestinal tract using immunohistochemistry and analyze their function(s) using neuroimaging techniques and pharmacological investigations. In order to perform a systematic and comparative study, we performed our experiments in gastrointestinal tissue from guinea pigs, mice and humans. Piezo1 (20-70%) is expressed by both enteric neuronal cell bodies and fibers in the myenteric and submucosal plexi of all the species investigated. Generally, Piezo1 expressing somata are more numerous in the submucosal plexus (50-80%) than in the myenteric plexus (15-35%) apart from the stomach where Piezo1 is expressed in up to 60% of cell bodies. Myenteric Piezo1 neurons mainly (60-100%) but not exclusively, also express nitric oxide synthase, a minority express choline acetyltransferase. In the submucosal plexus, Piezo1 neurons co-express vasoactive intestinal peptide (40-90%). Conversely, expression of Piezo2 is extremely rare in the somata of enteric neurons and is present in few neurites. In functional experiments, 38-76% of the mechanosensitive neurons expressed Piezo1 channels. Statistical analysis showed a positive significant correlation between mechanosensitive and Piezo1 positive neurons. However, pharmacological experiments using an activator and an inhibitor of Piezo channels did not demonstrate changes in mechanotransduction. A major role of Piezo1 in the mechanosensitivity of enteric neurons can be excluded.
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7
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Fung C, Koussoulas K, Unterweger P, Allen AM, Bornstein JC, Foong JPP. Cholinergic Submucosal Neurons Display Increased Excitability Following in Vivo Cholera Toxin Exposure in Mouse Ileum. Front Physiol 2018; 9:260. [PMID: 29618987 PMCID: PMC5871806 DOI: 10.3389/fphys.2018.00260] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 03/06/2018] [Indexed: 12/16/2022] Open
Abstract
Cholera-induced hypersecretion causes dehydration and death if untreated. Cholera toxin (CT) partly acts via the enteric nervous system (ENS) and induces long-lasting changes to enteric neuronal excitability following initial exposure, but the specific circuitry involved remains unclear. We examined this by first incubating CT or saline (control) in mouse ileal loops in vivo for 3.5 h and then assessed neuronal excitability in vitro using Ca2+ imaging and immunolabeling for the activity-dependent markers cFos and pCREB. Mice from a C57BL6 background, including Wnt1-Cre;R26R-GCaMP3 mice which express the fluorescent Ca2+ indicator GCaMP3 in its ENS, were used. Ca2+-imaging using this mouse model is a robust, high-throughput method which allowed us to examine the activity of numerous enteric neurons simultaneously and post-hoc immunohistochemistry enabled the neurochemical identification of the active neurons. Together, this provided novel insight into the CT-affected circuitry that was previously impossible to attain at such an accelerated pace. Ussing chamber measurements of electrogenic ion secretion showed that CT-treated preparations had higher basal secretion than controls. Recordings of Ca2+ activity from the submucous plexus showed that increased numbers of neurons were spontaneously active in CT-incubated tissue (control: 4/149; CT: 32/160; Fisher's exact test, P < 0.0001) and that cholinergic neurons were more responsive to electrical (single pulse and train of 20 pulses) or nicotinic (1,1-dimethyl-4-phenylpiperazinium (DMPP; 10 μM) stimulation. Expression of the neuronal activity marker, pCREB, was also increased in the CT-treated submucous plexus neurons. c-Fos expression and spontaneous fast excitatory postsynaptic potentials (EPSPs), recorded by intracellular electrodes, were increased by CT exposure in a small subset of myenteric neurons. However, the effect of CT on the myenteric plexus is less clear as spontaneous Ca2+ activity and electrical- or nicotinic-evoked Ca2+ responses were reduced. Thus, in a model where CT exposure evokes hypersecretion, we observed sustained activation of cholinergic secretomotor neuron activity in the submucous plexus, pointing to involvement of these neurons in the overall response to CT.
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Affiliation(s)
- Candice Fung
- Department of Physiology, The University of Melbourne, Parkville, VIC, Australia
| | - Katerina Koussoulas
- Department of Physiology, The University of Melbourne, Parkville, VIC, Australia
| | - Petra Unterweger
- Department of Physiology, The University of Melbourne, Parkville, VIC, Australia
| | - Andrew M Allen
- Department of Physiology, The University of Melbourne, Parkville, VIC, Australia.,Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Joel C Bornstein
- Department of Physiology, The University of Melbourne, Parkville, VIC, Australia
| | - Jaime P P Foong
- Department of Physiology, The University of Melbourne, Parkville, VIC, Australia
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8
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Buhner S, Hahne H, Hartwig K, Li Q, Vignali S, Ostertag D, Meng C, Hörmannsperger G, Braak B, Pehl C, Frieling T, Barbara G, De Giorgio R, Demir IE, Ceyhan GO, Zeller F, Boeckxstaens G, Haller D, Kuster B, Schemann M. Protease signaling through protease activated receptor 1 mediate nerve activation by mucosal supernatants from irritable bowel syndrome but not from ulcerative colitis patients. PLoS One 2018. [PMID: 29529042 PMCID: PMC5846775 DOI: 10.1371/journal.pone.0193943] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Background & aims The causes of gastrointestinal complaints in irritable bowel syndrome (IBS) remain poorly understood. Altered nerve function has emerged as an important pathogenic factor as IBS mucosal biopsy supernatants consistently activate enteric and sensory neurons. We investigated the neurally active molecular components of such supernatants from patients with IBS and quiescent ulcerative colitis (UC). Method Effects of supernatants from 7 healthy controls (HC), 20 IBS and 12 UC patients on human and guinea pig submucous neurons were studied with neuroimaging techniques. We identify differentially expressed proteins with proteome analysis. Results Nerve activation by IBS supernatants was prevented by the protease activated receptor 1 (PAR1) antagonist SCHE79797. UC supernatants also activated enteric neurons through protease dependent mechanisms but without PAR1 involvement. Proteome analysis of the supernatants identified 204 proteins, among them 17 proteases as differentially expressed between IBS, UC and HC. Of those the four proteases elastase 3a, chymotrypsin C, proteasome subunit type beta-2 and an unspecified isoform of complement C3 were significantly more abundant in IBS compared to HC and UC supernatants. Of eight proteases, which were upregulated in IBS, the combination of elastase 3a, cathepsin L and proteasome alpha subunit-4 showed the highest prediction accuracy of 98% to discriminate between IBS and HC groups. Elastase synergistically potentiated the effects of histamine and serotonin–the two other main neuroactive substances in the IBS supernatants. A serine protease inhibitor isolated from the probiotic Bifidobacterium longum NCC2705 (SERPINBL), known to inhibit elastase-like proteases, prevented nerve activation by IBS supernatants. Conclusion Proteases in IBS and UC supernatants were responsible for nerve activation. Our data demonstrate that proteases, particularly those signalling through neuronal PAR1, are biomarker candidates for IBS, and protease profiling may be used to characterise IBS.
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Affiliation(s)
- Sabine Buhner
- Human Biology, Technische Universität München, Freising, Germany
| | - Hannes Hahne
- Proteomics and Bioanalytics, Technische Universität München, Freising, Germany
| | - Kerstin Hartwig
- Human Biology, Technische Universität München, Freising, Germany
| | - Qin Li
- Human Biology, Technische Universität München, Freising, Germany
- Department of Physiology, Shangdong University, Shangdong, China
| | - Sheila Vignali
- Human Biology, Technische Universität München, Freising, Germany
| | - Daniela Ostertag
- Human Biology, Technische Universität München, Freising, Germany
| | - Chen Meng
- Proteomics and Bioanalytics, Technische Universität München, Freising, Germany
| | | | - Breg Braak
- Department of Gastroenterology and Hepatology, Academic Medical Center, Amsterdam, The Netherlands
| | | | | | - Giovanni Barbara
- Department of Medical and Surgical Sciences, St. Orsola Hospital, Bologna, Italy
| | - Roberto De Giorgio
- Department of Clinical Sciences, Nuovo Arcispedale S. Anna, University of Ferrara, Ferrara, Italy
| | - Ihsan Ekin Demir
- Department of General Surgery, University Hospital Rechts der Isar, Technische Universität München, Germany
| | - Güralp Onur Ceyhan
- Department of General Surgery, University Hospital Rechts der Isar, Technische Universität München, Germany
| | | | - Guy Boeckxstaens
- Translational Research Centre for Gastrointestinal Disorders, University Hospital Gasthuisberg, Catholic University of Leuven, Leuven, Belgium
| | - Dirk Haller
- Nutrition and Immunology, Technische Universität München, Freising, Germany
| | - Bernhard Kuster
- Proteomics and Bioanalytics, Technische Universität München, Freising, Germany
| | - Michael Schemann
- Human Biology, Technische Universität München, Freising, Germany
- * E-mail:
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9
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Koussoulas K, Swaminathan M, Fung C, Bornstein JC, Foong JPP. Neurally Released GABA Acts via GABA C Receptors to Modulate Ca 2+ Transients Evoked by Trains of Synaptic Inputs, but Not Responses Evoked by Single Stimuli, in Myenteric Neurons of Mouse Ileum. Front Physiol 2018; 9:97. [PMID: 29487540 PMCID: PMC5816811 DOI: 10.3389/fphys.2018.00097] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 01/29/2018] [Indexed: 12/16/2022] Open
Abstract
γ-Aminobutyric Acid (GABA) and its receptors, GABAA,B,C, are expressed in several locations along the gastrointestinal tract. Nevertheless, a role for GABA in enteric synaptic transmission remains elusive. In this study, we characterized the expression and function of GABA in the myenteric plexus of the mouse ileum. About 8% of all myenteric neurons were found to be GABA-immunoreactive (GABA+) including some Calretinin+ and some neuronal nitric oxide synthase (nNOS+) neurons. We used Wnt1-Cre;R26R-GCaMP3 mice, which express a genetically encoded fluorescent calcium indicator in all enteric neurons and glia. Exogenous GABA increased the intracellular calcium concentration, [Ca2+]i of some myenteric neurons including many that did not express GABA or nNOS (the majority), some GABA+, Calretinin+ or Neurofilament-M (NFM)+ but rarely nNOS+ neurons. GABA+ terminals contacted a significantly larger proportion of the cell body surface area of Calretinin+ neurons than of nNOS+ neurons. Numbers of neurons with GABA-induced [Ca2+]i transients were reduced by GABAA,B,C and nicotinic receptor blockade. Electrical stimulation of interganglionic fiber tracts was used to examine possible effects of endogenous GABA release. [Ca2+]i transients evoked by single pulses were unaffected by specific antagonists for each of the 3 GABA receptor subtypes. [Ca2+]i transients evoked by 20 pulse trains were significantly amplified by GABAC receptor blockade. These data suggest that GABAA and GABAB receptors are not involved in synaptic transmission, but suggest a novel role for GABAC receptors in modulating slow synaptic transmission, as indicated by changes in [Ca2+]i transients, within the ENS.
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Affiliation(s)
| | | | | | | | - Jaime P. P. Foong
- Department of Physiology, University of Melbourne, Parkville, VIC, Australia
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10
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Kugler EM, Michel K, Kirchenbüchler D, Dreissen G, Csiszár A, Merkel R, Schemann M, Mazzuoli-Weber G. Sensitivity to Strain and Shear Stress of Isolated Mechanosensitive Enteric Neurons. Neuroscience 2018; 372:213-224. [PMID: 29317262 DOI: 10.1016/j.neuroscience.2017.12.052] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 12/20/2017] [Accepted: 12/27/2017] [Indexed: 10/18/2022]
Abstract
Within the enteric nervous system, the neurons in charge to control motility of the gastrointestinal tract reside in a particular location nestled between two perpendicular muscle layers which contract and relax. We used primary cultured myenteric neurons of male guinea pigs to study mechanosensitivity of enteric neurons in isolation. Ultrafast Neuroimaging with a voltage-sensitive dye technique was used to record neuronal activity in response to shear stress and strain. Strain was induced by locally deforming the elastic cell culture substrate next to a neuron. Measurements showed that substrate strain was mostly elongating cells. Shear stress was exerted by hydrodynamic forces in a microchannel. Both stimuli induced excitatory responses. Strain activated 14% of the stimulated myenteric neurons that responded with a spike frequency of 1.9 (0.7/3.2) Hz, whereas shear stress excited only a few neurons (5.6%) with a very low spike frequency of 0 (0/0.6) Hz. Thus, shear stress does not seem to be an adequate stimulus for mechanosensitive enteric neurons (MEN) while strain activates enteric neurons in a relevant manner. Analyzing the adaptation behavior of MEN showed that shear stress activated rapidly/slowly/ultraslowly adapting MEN (2/62/36%) whereas strain only slowly (46%) and ultraslowly (54%) MEN. Paired experiments with strain and normal stress revealed three mechanosensitive enteric neuronal populations: one strain-sensitive (37%), one normal stress-sensitive (17%) and one strain- and stress-sensitive (46%). These results indicate that shear stress does not play a role in the neuronal control of motility but normal stress and strain.
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Affiliation(s)
- Eva Maria Kugler
- Human Biology, Technische Universität München, Freising-Weihenstephan, 85354, Germany.
| | - Klaus Michel
- Human Biology, Technische Universität München, Freising-Weihenstephan, 85354, Germany.
| | - David Kirchenbüchler
- Institute of Complex Systems - Biomechanics, Research Center Jülich, 52425 Jülich, Germany.
| | - Georg Dreissen
- Institute of Complex Systems - Biomechanics, Research Center Jülich, 52425 Jülich, Germany.
| | - Agnes Csiszár
- Institute of Complex Systems - Biomechanics, Research Center Jülich, 52425 Jülich, Germany.
| | - Rudolf Merkel
- Institute of Complex Systems - Biomechanics, Research Center Jülich, 52425 Jülich, Germany.
| | - Michael Schemann
- Human Biology, Technische Universität München, Freising-Weihenstephan, 85354, Germany.
| | - Gemma Mazzuoli-Weber
- Human Biology, Technische Universität München, Freising-Weihenstephan, 85354, Germany.
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11
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Hibberd TJ, Travis L, Wiklendt L, Costa M, Brookes SJH, Hu H, Keating DJ, Spencer NJ. Synaptic activation of putative sensory neurons by hexamethonium-sensitive nerve pathways in mouse colon. Am J Physiol Gastrointest Liver Physiol 2018; 314:G53-G64. [PMID: 28935683 DOI: 10.1152/ajpgi.00234.2017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The gastrointestinal tract contains its own independent population of sensory neurons within the gut wall. These sensory neurons have been referred to as intrinsic primary afferent neurons (IPANs) and can be identified by immunoreactivity to calcitonin gene-related peptide (CGRP) in mice. A common feature of IPANs is a paucity of fast synaptic inputs observed during sharp microelectrode recordings. Whether this is observed using different recording techniques is of particular interest for understanding the physiology of these neurons and neural circuit modeling. Here, we imaged spontaneous and evoked activation of myenteric neurons in isolated whole preparations of mouse colon and correlated recordings with CGRP and nitric oxide synthase (NOS) immunoreactivity, post hoc. Calcium indicator fluo 4 was used for this purpose. Calcium responses were recorded in nerve cell bodies located 5-10 mm oral to transmural electrical nerve stimuli. A total of 618 recorded neurons were classified for CGRP or NOS immunoreactivity. Aboral electrical stimulation evoked short-latency calcium transients in the majority of myenteric neurons, including ~90% of CGRP-immunoreactive Dogiel type II neurons. Activation of Dogiel type II neurons had a time course consistent with fast synaptic transmission and was always abolished by hexamethonium (300 μM) and by low-calcium Krebs solution. The nicotinic receptor agonist 1,1-dimethyl-4-phenylpiperazinium iodide (during synaptic blockade) directly activated Dogiel type II neurons. The present study suggests that murine colonic Dogiel type II neurons receive prominent fast excitatory synaptic inputs from hexamethonium-sensitive neural pathways. NEW & NOTEWORTHY Myenteric neurons in isolated mouse colon were recorded using calcium imaging and then neurochemically defined. Short-latency calcium transients were detected in >90% of calcitonin gene-related peptide-immunoreactive neurons to electrical stimulation of hexamethonium-sensitive pathways. Putative sensory Dogiel type II calcitonin gene-related peptide-immunoreactive myenteric neurons may receive widespread fast synaptic inputs in mouse colon.
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Affiliation(s)
- Timothy J Hibberd
- Discipline of Human Physiology and Centre for Neuroscience, Flinders University , Adelaide South Australia
| | - Lee Travis
- Discipline of Human Physiology and Centre for Neuroscience, Flinders University , Adelaide South Australia
| | - Lukasz Wiklendt
- Discipline of Human Physiology and Centre for Neuroscience, Flinders University , Adelaide South Australia
| | - Marcello Costa
- Discipline of Human Physiology and Centre for Neuroscience, Flinders University , Adelaide South Australia
| | - Simon J H Brookes
- Discipline of Human Physiology and Centre for Neuroscience, Flinders University , Adelaide South Australia
| | - Hongzhen Hu
- Department of Anesthesiology, Washington University , Saint Louis, Missouri
| | - Damien J Keating
- Discipline of Human Physiology and Centre for Neuroscience, Flinders University , Adelaide South Australia
| | - Nick J Spencer
- Discipline of Human Physiology and Centre for Neuroscience, Flinders University , Adelaide South Australia
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Buhner S, Barki N, Greiter W, Giesbertz P, Demir IE, Ceyhan GO, Zeller F, Daniel H, Schemann M. Calcium Imaging of Nerve-Mast Cell Signaling in the Human Intestine. Front Physiol 2017; 8:971. [PMID: 29238306 PMCID: PMC5712982 DOI: 10.3389/fphys.2017.00971] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 11/14/2017] [Indexed: 12/12/2022] Open
Abstract
Introduction: It is suggested that an altered microenvironment in the gut wall alters communication along a mast cell nerve axis. We aimed to record for the first time signaling between mast cells and neurons in intact human submucous preparations. Methods: We used the Ca2+ sensitive dye Fluo-4 AM to simultaneously image changes in intracellular calcium [Ca+2]i (%ΔF/F) in neurons and mast cells. Data are presented as median with interquartile ranges (25/75%). Results: We recorded nerve responses in 29 samples upon selective activation of 223 mast cells by IgE receptor cross linking with the antibody mAb22E7. Mast cells responded to mAb22E7 with a median [Ca+2]i increase of 20% (11/39) peaking 90 s (64/144) after the application. Only very few neurons responded and the median percentage of responding neuronal area was 0% (0/5.9). Mast cell activation remained in the presence of the fast sodium channel blocker tetrodotoxin. Specific neuronal activation by transmural electrical field stimulation (EFS) in 34 samples evoked instantaneously [Ca+2]i signals in submucous neurons. This was followed by a [Ca+2]i peak response of 8%ΔF/F (4/15) in 33% of 168 mast cells in the field of view. The mast cell response was abolished by the nerve blocker tetrododoxin, reduced by the Calcitonin Gene-Related Peptide receptor 1 antagonist BIBN-4096 and the Vasoactive Intestinal Peptide receptor antagonist PG97-269, but not by blockade of the neurokinin receptors 1-3. Conclusion: The findings revealed bidirectional signaling between mast cells and submucous neurons in human gut. In our macroscopically normal preparations a nerve to mast cell signaling was very prominent whereas a mast cell to nerve signaling was rather rare.
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Affiliation(s)
- Sabine Buhner
- Human Biology, Technische Universität München, Freising, Germany
| | - Natasja Barki
- Human Biology, Technische Universität München, Freising, Germany
| | - Wolfgang Greiter
- Human Biology, Technische Universität München, Freising, Germany
| | - Pieter Giesbertz
- Molecular Nutrition Unit, Technische Universität München, Freising, Germany
| | - Ihsan E. Demir
- Department of General Surgery, University Hospital Rechts der Isar, Technische Universität München, Munich, Germany
| | - Güralp O. Ceyhan
- Department of General Surgery, University Hospital Rechts der Isar, Technische Universität München, Munich, Germany
| | | | - Hannelore Daniel
- Molecular Nutrition Unit, Technische Universität München, Freising, Germany
| | - Michael Schemann
- Human Biology, Technische Universität München, Freising, Germany
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13
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Ostertag D, Annahazi A, Krueger D, Michel K, Demir IE, Ceyhan GO, Zeller F, Schemann M. Tryptase potentiates enteric nerve activation by histamine and serotonin: Relevance for the effects of mucosal biopsy supernatants from irritable bowel syndrome patients. Neurogastroenterol Motil 2017; 29. [PMID: 28374503 DOI: 10.1111/nmo.13070] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 02/23/2017] [Indexed: 01/02/2023]
Abstract
BACKGROUND We previously showed that mucosal biopsy supernatants from irritable bowel syndrome patients activated neurons despite low concentrations of tryptase, histamine, and serotonin which individually would not cause spike discharge. We studied the potentiating responses between these mediators on excitability of enteric neurons. METHODS Calcium-imaging was performed using the calcium-sensitive dye Fluo-4 AM in human submucous plexus preparations from 45 individuals. Histamine, serotonin, and tryptase were applied alone and in combinations to evaluate nerve activation which was assessed by analyzing increase in intracellular Ca2+ ([Ca2+ ]i ), the proportion of responding neurons and the product of both defined as Ca-neuroindex (NI). Protease activated receptor (PAR) 2 activating peptide, PAR2 antagonist and the serine protease-inhibitor FUT-175 were used to particularly investigate the role of proteases. KEY RESULTS Histamine or serotonin (1 μmol/L each) evoked only few small responses (median NI [25%/75%]: 0 [0/148]; 85 [0/705] respectively). Their combined application evoked statistically similar responses (216 [21/651]). Addition of the PAR2 activator tryptase induced a significantly higher Ca-NI (1401 [867/4075]) compared to individual application of tryptase or to coapplied histamine and serotonin. This synergistic potentiation was neither mimicked by PAR2 activating peptide nor reversed by the PAR2 antagonist GB83, but abolished by FUT-175. CONCLUSIONS & INFERENCES We observed synergistic potentiation between histamine, serotonin, and tryptase in enteric neurons, which is mediated by proteolytic activity rather than PAR2 activation. This explained neuronal activation by a cocktail of these mediators despite their low concentrations and despite a relatively small PAR2-mediated response in human submucous neurons.
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Affiliation(s)
- D Ostertag
- Human Biology, Technical University of Munich, Freising, Germany
| | - A Annahazi
- Human Biology, Technical University of Munich, Freising, Germany
| | - D Krueger
- Human Biology, Technical University of Munich, Freising, Germany
| | - K Michel
- Human Biology, Technical University of Munich, Freising, Germany
| | - I E Demir
- Department of Surgery, Klinikum Rechts der Isar, Technical University of Munich, Munich, Germany
| | - G O Ceyhan
- Department of Surgery, Klinikum Rechts der Isar, Technical University of Munich, Munich, Germany
| | - F Zeller
- Department of Surgery, Klinikum Freising, Freising, Germany
| | - M Schemann
- Human Biology, Technical University of Munich, Freising, Germany
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14
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Excitability and Synaptic Transmission in the Enteric Nervous System: Does Diet Play a Role? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 891:201-11. [PMID: 27379647 DOI: 10.1007/978-3-319-27592-5_19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Changes in diet are a challenge to the gastrointestinal tract which needs to alter its processing mechanisms to continue to process nutrients and maintain health. In particular, the enteric nervous system (ENS) needs to adapt its motor and secretory programs to deal with changes in nutrient type and load in order to optimise nutrient absorption.The nerve circuits in the gut are complex, and the numbers and types of neurons make recordings of specific cell types difficult, time-consuming, and prone to sampling errors. Nonetheless, traditional research methods like intracellular electrophysiological approaches have provided the basis for our understanding of the ENS circuitry. In particular, animal models of intestinal inflammation have shown us that we can document changes to neuronal excitability and synaptic transmission.Recent studies examining diet-induced changes to ENS programming have opted to use fast imaging techniques to reveal changes in neuron function. Advances in imaging techniques using voltage- or calcium-sensitive dyes to record neuronal activity promise to overcome many limitations inherent to electrophysiological approaches. Imaging techniques allow access to a wide range of ENS phenotypes and to the changes they undergo during dietary challenges. These sorts of studies have shown that dietary variation or obesity can change how the ENS processes information-in effect reprogramming the ENS. In this review, the data gathered from intracellular recordings will be compared with measurements made using imaging techniques in an effort to determine if the lessons learnt from inflammatory changes are relevant to the understanding of diet-induced reprogramming.
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Fung C, Boesmans W, Cirillo C, Foong JPP, Bornstein JC, Vanden Berghe P. VPAC Receptor Subtypes Tune Purinergic Neuron-to-Glia Communication in the Murine Submucosal Plexus. Front Cell Neurosci 2017; 11:118. [PMID: 28487635 PMCID: PMC5403822 DOI: 10.3389/fncel.2017.00118] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 04/10/2017] [Indexed: 12/20/2022] Open
Abstract
The enteric nervous system (ENS) situated within the gastrointestinal tract comprises an intricate network of neurons and glia which together regulate intestinal function. The exact neuro-glial circuitry and the signaling molecules involved are yet to be fully elucidated. Vasoactive intestinal peptide (VIP) is one of the main neurotransmitters in the gut, and is important for regulating intestinal secretion and motility. However, the role of VIP and its VPAC receptors within the enteric circuitry is not well understood. We investigated this in the submucosal plexus of mouse jejunum using calcium (Ca2+)-imaging. Local VIP application induced Ca2+-transients primarily in neurons and these were inhibited by VPAC1- and VPAC2-antagonists (PG 99-269 and PG 99-465 respectively). These VIP-evoked neural Ca2+-transients were also inhibited by tetrodotoxin (TTX), indicating that they were secondary to action potential generation. Surprisingly, VIP induced Ca2+-transients in glia in the presence of the VPAC2 antagonist. Further, selective VPAC1 receptor activation with the agonist ([K15, R16, L27]VIP(1-7)/GRF(8-27)) predominantly evoked glial responses. However, VPAC1-immunoreactivity did not colocalize with the glial marker glial fibrillary acidic protein (GFAP). Rather, VPAC1 expression was found on cholinergic submucosal neurons and nerve fibers. This suggests that glial responses observed were secondary to neuronal activation. Trains of electrical stimuli were applied to fiber tracts to induce endogenous VIP release. Delayed glial responses were evoked when the VPAC2 antagonist was present. These findings support the presence of an intrinsic VIP/VPAC-initiated neuron-to-glia signaling pathway. VPAC1 agonist-evoked glial responses were inhibited by purinergic antagonists (PPADS and MRS2179), thus demonstrating the involvement of P2Y1 receptors. Collectively, we showed that neurally-released VIP can activate neurons expressing VPAC1 and/or VPAC2 receptors to modulate purine-release onto glia. Selective VPAC1 activation evokes a glial response, whereas VPAC2 receptors may act to inhibit this response. Thus, we identified a component of an enteric neuron-glia circuit that is fine-tuned by endogenous VIP acting through VPAC1- and VPAC2-mediated pathways.
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Affiliation(s)
- Candice Fung
- Department of Physiology, The University of MelbourneParkville, VIC, Australia.,Laboratory for Enteric Neuroscience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), KU LeuvenLeuven, Belgium
| | - Werend Boesmans
- Laboratory for Enteric Neuroscience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), KU LeuvenLeuven, Belgium
| | - Carla Cirillo
- Laboratory for Enteric Neuroscience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), KU LeuvenLeuven, Belgium
| | - Jaime P P Foong
- Department of Physiology, The University of MelbourneParkville, VIC, Australia
| | - Joel C Bornstein
- Department of Physiology, The University of MelbourneParkville, VIC, Australia
| | - Pieter Vanden Berghe
- Laboratory for Enteric Neuroscience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), KU LeuvenLeuven, Belgium
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16
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Li Q, Michel K, Annahazi A, Demir IE, Ceyhan GO, Zeller F, Komorowski L, Stöcker W, Beyak MJ, Grundy D, Farrugia G, De Giorgio R, Schemann M. Anti-Hu antibodies activate enteric and sensory neurons. Sci Rep 2016; 6:38216. [PMID: 27905561 PMCID: PMC5131267 DOI: 10.1038/srep38216] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 11/07/2016] [Indexed: 02/07/2023] Open
Abstract
IgG of type 1 anti-neuronal nuclear antibody (ANNA-1, anti-Hu) specificity is a serological marker of paraneoplastic neurological autoimmunity (including enteric/autonomic) usually related to small-cell lung carcinoma. We show here that IgG isolated from such sera and also affinity-purified anti-HuD label enteric neurons and cause an immediate spike discharge in enteric and visceral sensory neurons. Both labelling and activation of enteric neurons was prevented by preincubation with the HuD antigen. Activation of enteric neurons was inhibited by the nicotinic receptor antagonists hexamethonium and dihydro-β-erythroidine and reduced by the P2X antagonist pyridoxal phosphate-6-azo (benzene-2,4-disulfonic acid (PPADS) but not by the 5-HT3 antagonist tropisetron or the N-type Ca-channel blocker ω-Conotoxin GVIA. Ca++ imaging experiments confirmed activation of enteric neurons but not enteric glia. These findings demonstrate a direct excitatory action of ANNA-1, in particular anti-HuD, on visceral sensory and enteric neurons, which involves nicotinic and P2X receptors. The results provide evidence for a novel link between nerve activation and symptom generation in patients with antibody-mediated gut dysfunction.
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Affiliation(s)
- Qin Li
- Human Biology, Technical University of Munich, Freising, Germany.,Department of Physiology, Shandong University School of Medicine, Jinan, China
| | - Klaus Michel
- Human Biology, Technical University of Munich, Freising, Germany
| | - Anita Annahazi
- Human Biology, Technical University of Munich, Freising, Germany
| | - Ihsan E Demir
- Department of Surgery, Klinikum Rechts der Isar, Technical University of Munich; Munich, Germany
| | - Güralp O Ceyhan
- Department of Surgery, Klinikum Rechts der Isar, Technical University of Munich; Munich, Germany
| | | | - Lars Komorowski
- Institute for Experimental Immunology, Euroimmun AG, Lübeck, Germany
| | - Winfried Stöcker
- Institute for Experimental Immunology, Euroimmun AG, Lübeck, Germany
| | - Michael J Beyak
- GI Diseases Research Unit, Queen's University, Kingston, ON, Canada
| | - David Grundy
- Department of Biomedical Sciences, University of Sheffield, Sheffield, UK
| | | | - Roberto De Giorgio
- Department of Medical and Surgical Sciences and Center for Applied Biomedical Research, University of Bologna, Bologna, Italy
| | - Michael Schemann
- Human Biology, Technical University of Munich, Freising, Germany
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17
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Mañé N, Viais R, Martínez-Cutillas M, Gallego D, Correia-de-Sá P, Jiménez M. Inverse gradient of nitrergic and purinergic inhibitory cotransmission in the mouse colon. Acta Physiol (Oxf) 2016; 216:120-31. [PMID: 26347033 DOI: 10.1111/apha.12599] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 07/09/2015] [Accepted: 09/02/2015] [Indexed: 02/06/2023]
Abstract
AIM Gastrointestinal smooth muscle relaxation is accomplished by the neural corelease of ATP or a related purine and nitric oxide. Contractions are triggered by acetylcholine and tachykinins. The aim of this work was to study whether regional differences in neurotransmission could partially explain the varied physiological roles of each colonic area. METHODS We used electrophysiological and myography techniques to evaluate purinergic (L-NNA 1 mm incubated tissue), nitrergic (MRS2500 0.3 μm incubated tissue) and cholinergic neurotransmission (L-NNA 1 mm and MRS2500 0.3 μm incubated tissue) in the proximal, mid and distal colon of CD1 mice (n = 42). RESULTS Purinergic electrophysiological responses elicited by single pulses (28 V) were greater in the distal (IJPfMAX = -35.3 ± 2.2 mV), followed by the mid (IJPfMAX = -30.6 ± 1.0 mV) and proximal (IJPfMAX = -11.7 ± 1.1 mV) colon. In contrast, nitrergic responses decreased from the proximal colon (IJPsMAX = -11.4 ± 1.1 mV) to the mid (IJPsMAX = -9.1 ± 0.4 mV), followed by the distal colon (IJPsMAX = -1.8 ± 0.3 mV). A similar rank of order was observed in neural mediated inhibitory mechanical responses including electrical field stimulation-mediated responses and neural tone. ADPβs concentration-response curve was shifted to the left in the distal colon. In contrast, NaNP responses did not differ between regions. Cholinergic neurotransmission elicited contractions of a similar amplitude throughout the colon. CONCLUSION An inverse gradient of purinergic and nitrergic neurotransmission exists through the mouse colon. The proximal and mid colon have a predominant nitrergic neurotransmission probably due to the fact that their storage function requires sustained relaxations. The distal colon, in contrast, has mainly purinergic neurotransmission responsible for the phasic relaxations needed to propel dehydrated faeces.
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Affiliation(s)
- N. Mañé
- Department of Cell Biology, Physiology and Immunology and Neuroscience Institute; Universitat Autònoma de Barcelona; Barcelona Spain
| | - R. Viais
- Center for Drug Discovery and Innovative Medicines (MedInUP); Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto (ICBAS-UP); Porto Portugal
| | - M. Martínez-Cutillas
- Department of Cell Biology, Physiology and Immunology and Neuroscience Institute; Universitat Autònoma de Barcelona; Barcelona Spain
| | - D. Gallego
- Department of Cell Biology, Physiology and Immunology and Neuroscience Institute; Universitat Autònoma de Barcelona; Barcelona Spain
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd); Instituto de Salud Carlos III; Barcelona Spain
| | - P. Correia-de-Sá
- Center for Drug Discovery and Innovative Medicines (MedInUP); Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto (ICBAS-UP); Porto Portugal
| | - M. Jiménez
- Department of Cell Biology, Physiology and Immunology and Neuroscience Institute; Universitat Autònoma de Barcelona; Barcelona Spain
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd); Instituto de Salud Carlos III; Barcelona Spain
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18
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Advanced 3D Optical Microscopy in ENS Research. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 891:193-9. [DOI: 10.1007/978-3-319-27592-5_18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Three-Dimensional Gastrointestinal Organoid Culture in Combination with Nerves or Fibroblasts: A Method to Characterize the Gastrointestinal Stem Cell Niche. Stem Cells Int 2015; 2016:3710836. [PMID: 26697073 PMCID: PMC4677245 DOI: 10.1155/2016/3710836] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 07/06/2015] [Accepted: 07/09/2015] [Indexed: 12/12/2022] Open
Abstract
The gastrointestinal epithelium is characterized by a high turnover of cells and intestinal stem cells predominantly reside at the bottom of crypts and their progeny serve to maintain normal intestinal homeostasis. Accumulating evidence demonstrates the pivotal role of a niche surrounding intestinal stem cells in crypts, which consists of cellular and soluble components and creates an environment constantly influencing the fate of stem cells. Here we describe different 3D culture systems to culture gastrointestinal epithelium that should enable us to study the stem cell niche in vitro in the future: organoid culture and multilayered systems such as organotypic cell culture and culture of intestinal tissue fragments ex vivo. These methods mimic the in vivo situation in vitro by creating 3D culture conditions that reflect the physiological situation of intestinal crypts. Modifications of the composition of the culture media as well as coculturing epithelial organoids with previously described cellular components such as myofibroblasts, collagen, and neurons show the impact of the methods applied to investigate niche interactions in vitro. We further present a novel method to isolate labeled nerves from the enteric nervous system using Dclk1-CreGFP mice.
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20
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Mazzuoli-Weber G, Schemann M. Mechanosensitive enteric neurons in the guinea pig gastric corpus. Front Cell Neurosci 2015; 9:430. [PMID: 26578888 PMCID: PMC4630284 DOI: 10.3389/fncel.2015.00430] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 10/13/2015] [Indexed: 01/27/2023] Open
Abstract
For long it was believed that a particular population of enteric neurons, referred to as intrinsic primary afferent neuron (IPAN)s, encodes mechanical stimulation. We recently proposed a new concept suggesting that there are in addition mechanosensitive enteric neurons (MEN) that are multifunctional. Based on firing pattern MEN behaved as rapidly, slowly, or ultra-slowly adapting RAMEN, SAMEN, or USAMEN, respectively. We aimed to validate this concept in the myenteric plexus of the gastric corpus, a region where IPANs were not identified and existence of enteric sensory neurons was even questioned. The gastric corpus is characterized by a particularly dense extrinsic sensory innervation. Neuronal activity was recorded with voltage sensitive dye imaging after deformation of ganglia by compression (intraganglionic volume injection or von Fry hair) or tension (ganglionic stretch). We demonstrated that 27% of the gastric neurons were MEN and responded to intraganglionic volume injection. Of these 73% were RAMEN, 25% SAMEN, and 2% USAMEN with a firing frequency of 1.7 (1.1/2.2), 5.1 (2.2/7.7), and of 5.4 (5.0/15.5) Hz, respectively. The responses were reproducible and stronger with increased stimulus strength. Even after adaptation another deformation evoked spike discharge again suggesting a resetting mode of the mechanoreceptors. All MEN received fast synaptic input. Fifty five percent of all MEN were cholinergic and 45% nitrergic. Responses in some MEN significantly decreased after perfusion of TTX, low Ca(++)/high Mg(++) Krebs solution, capsaicin induced nerve defunctionalization and capsazepine indicating the involvement of TRPV1 expressing extrinsic mechanosensitive nerves. Half of gastric MEN responded to intraganglionic volume injection as well as to ganglionic stretch and 23% responded to stretch only. Tension-sensitive MEN were to a large proportion USAMEN (44%). In summary, we demonstrated for the first time compression and tension-sensitive MEN in the stomach; many of them responded to one stimulus modality only. Their proportions and the basic properties were similar to MEN previously identified by us in other intestinal region and species. Unlike in the intestine, the responsiveness of some gastric MEN is enhanced by extrinsic TRPV1 expressing visceral afferents.
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Affiliation(s)
| | - Michael Schemann
- Human Biology, Technische Universitaet Muenchen Freising, Germany
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21
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Kugler EM, Michel K, Zeller F, Demir IE, Ceyhan GO, Schemann M, Mazzuoli-Weber G. Mechanical stress activates neurites and somata of myenteric neurons. Front Cell Neurosci 2015; 9:342. [PMID: 26441520 PMCID: PMC4569744 DOI: 10.3389/fncel.2015.00342] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 08/18/2015] [Indexed: 12/24/2022] Open
Abstract
The particular location of myenteric neurons, sandwiched between the 2 muscle layers of the gut, implies that their somata and neurites undergo mechanical stress during gastrointestinal motility. Existence of mechanosensitive enteric neurons (MEN) is undoubted but many of their basic features remain to be studied. In this study, we used ultra-fast neuroimaging to record activity of primary cultured myenteric neurons of guinea pig and human intestine after von Frey hair evoked deformation of neurites and somata. Independent component analysis was applied to reconstruct neuronal morphology and follow neuronal signals. Of the cultured neurons 45% (114 out of 256, 30 guinea pigs) responded to neurite probing with a burst spike frequency of 13.4 Hz. Action potentials generated at the stimulation site invaded the soma and other neurites. Mechanosensitive sites were expressed across large areas of neurites. Many mechanosensitive neurites appeared to have afferent and efferent functions as those that responded to deformation also conducted spikes coming from the soma. Mechanosensitive neurites were also activated by nicotine application. This supported the concept of multifunctional MEN. 14% of the neurons (13 out of 96, 18 guinea pigs) responded to soma deformation with burst spike discharge of 17.9 Hz. Firing of MEN adapted rapidly (RAMEN), slowly (SAMEN), or ultra-slowly (USAMEN). The majority of MEN showed SAMEN behavior although significantly more RAMEN occurred after neurite probing. Cultured myenteric neurons from human intestine had similar properties. Compared to MEN, dorsal root ganglion neurons were activated by neurite but not by soma deformation with slow adaptation of firing. We demonstrated that MEN exhibit specific features very likely reflecting adaptation to their specialized functions in the gut.
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Affiliation(s)
- Eva M Kugler
- Human Biology, Technische Universitaet Muenchen Freising, Germany
| | - Klaus Michel
- Human Biology, Technische Universitaet Muenchen Freising, Germany
| | - Florian Zeller
- Department of Surgery, Klinikum Freising Freising, Germany
| | - Ihsan E Demir
- Department of Surgery, Klinikum Rechts der Isar, Technische Universitaet Muenchen Munich, Germany
| | - Güralp O Ceyhan
- Department of Surgery, Klinikum Rechts der Isar, Technische Universitaet Muenchen Munich, Germany
| | - Michael Schemann
- Human Biology, Technische Universitaet Muenchen Freising, Germany
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Boesmans W, Hao MM, Vanden Berghe P. Optical Tools to Investigate Cellular Activity in the Intestinal Wall. J Neurogastroenterol Motil 2015; 21:337-51. [PMID: 26130630 PMCID: PMC4496899 DOI: 10.5056/jnm15096] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 06/10/2015] [Indexed: 12/13/2022] Open
Abstract
Live imaging has become an essential tool to investigate the coordinated activity and output of cellular networks. Within the last decade, 2 Nobel prizes have been awarded to recognize innovations in the field of imaging: one for the discovery, use, and optimization of the green fluorescent protein (2008) and the second for the development of super-resolved fluorescence microscopy (2014). New advances in both optogenetics and microscopy now enable researchers to record and manipulate activity from specific populations of cells with better contrast and resolution, at higher speeds, and deeper into live tissues. In this review, we will discuss some of the recent developments in microscope technology and in the synthesis of fluorescent probes, both synthetic and genetically encoded. We focus on how live imaging of cellular physiology has progressed our understanding of the control of gastrointestinal motility, and we discuss the hurdles to overcome in order to apply the novel tools in the field of neurogastroenterology and motility.
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Affiliation(s)
- Werend Boesmans
- Laboratory for Enteric NeuroScience (LENS), Translational Research Center for GastroIntestinal Disorders (TARGID), Department of Clinical and Experimental Medicine, University of Leuven, Leuven, Belgium
| | - Marlene M Hao
- Laboratory for Enteric NeuroScience (LENS), Translational Research Center for GastroIntestinal Disorders (TARGID), Department of Clinical and Experimental Medicine, University of Leuven, Leuven, Belgium
| | - Pieter Vanden Berghe
- Laboratory for Enteric NeuroScience (LENS), Translational Research Center for GastroIntestinal Disorders (TARGID), Department of Clinical and Experimental Medicine, University of Leuven, Leuven, Belgium
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Hawkins JL, Denson JE, Miley DR, Durham PL. Nicotine stimulates expression of proteins implicated in peripheral and central sensitization. Neuroscience 2015; 290:115-25. [PMID: 25637801 PMCID: PMC5894823 DOI: 10.1016/j.neuroscience.2015.01.034] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 12/19/2014] [Accepted: 01/07/2015] [Indexed: 12/26/2022]
Abstract
Pain patients who are nicotine dependent report a significantly increased incidence and severity of pain intensity. The goal of this study was to determine the effects of prolonged nicotine administration on inflammatory proteins implicated in the development of peripheral and central sensitization of the trigeminal system. Behavioral, immunohistochemical, and microarray studies were utilized to investigate the effects of nicotine administered daily for 14 days via an Alzet® osmotic pump in Sprague Dawley rats. Systemic nicotine administration caused a significant increase in nocifensive withdrawals to mechanical stimulation of trigeminal neurons. Nicotine stimulated expression of the pro-inflammatory signal transduction proteins phosphorylated-extracellular signal-regulated kinase (p-ERK), phosphorylated-c-Jun N-terminal kinase (p-JNK), and protein kinase A (PKA) in the spinal trigeminal nucleus. Nicotine also promoted elevations in the expression of glial fibrillary acidic protein (GFAP), a biomarker of activated astrocytes, and the microglia biomarker ionized calcium-binding adapter molecule 1 (Iba1). Similarly, levels of eleven cytokines were significantly elevated with the largest increase in expression of TNF-α. Levels of PKA, p-ERK, and p-JNK in trigeminal ganglion neurons were increased by nicotine. Our findings demonstrate that prolonged systemic administration of nicotine promotes sustained behavioral and cellular changes in the expression of key proteins in the spinal trigeminal nucleus and trigeminal ganglion implicated in the development and maintenance of peripheral and central sensitization.
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Affiliation(s)
- J L Hawkins
- Center for Biomedical & Life Sciences, Missouri State University, Springfield, MO, USA
| | - J E Denson
- Center for Biomedical & Life Sciences, Missouri State University, Springfield, MO, USA
| | - D R Miley
- Center for Biomedical & Life Sciences, Missouri State University, Springfield, MO, USA
| | - P L Durham
- Center for Biomedical & Life Sciences, Missouri State University, Springfield, MO, USA.
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Liñán-Rico A, Wunderlich JE, Enneking JT, Tso DR, Grants I, Williams KC, Otey A, Michel K, Schemann M, Needleman B, Harzman A, Christofi FL. Neuropharmacology of purinergic receptors in human submucous plexus: Involvement of P2X₁, P2X₂, P2X₃ channels, P2Y and A₃ metabotropic receptors in neurotransmission. Neuropharmacology 2015; 95:83-99. [PMID: 25724083 DOI: 10.1016/j.neuropharm.2015.02.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 02/11/2015] [Accepted: 02/15/2015] [Indexed: 02/08/2023]
Abstract
RATIONALE The role of purinergic signaling in human ENS is not well understood. We sought to further characterize the neuropharmacology of purinergic receptors in human ENS and test the hypothesis that endogenous purines are critical regulators of neurotransmission. EXPERIMENTAL APPROACH LSCM-Fluo-4/(Ca(2+))-imaging of postsynaptic Ca(2+) transients (PSCaTs) was used as a reporter of synaptic transmission evoked by fiber tract electrical stimulation in human SMP surgical preparations. Pharmacological analysis of purinergic signaling was done in 1,556 neurons (identified by HuC/D-immunoreactivity) in 235 ganglia from 107 patients; P2XR-immunoreactivity was evaluated in 19 patients. Real-time MSORT (Di-8-ANEPPS) imaging tested effects of adenosine on fast excitatory synaptic potentials (fEPSPs). RESULTS Synaptic transmission is sensitive to pharmacological manipulations that alter accumulation of extracellular purines: Apyrase blocks PSCaTs in a majority of neurons. An ecto-NTPDase-inhibitor 6-N,N-diethyl-D-β,γ-dibromomethyleneATP or adenosine deaminase augments PSCaTs. Blockade of reuptake/deamination of eADO inhibits PSCaTs. Adenosine inhibits fEPSPs and PSCaTs (IC50 = 25 µM), sensitive to MRS1220-antagonism (A3AR). A P2Y agonist ADPβS inhibits PSCaTs (IC50 = 111 nM) in neurons without stimulatory ADPbS responses (EC50 = 960 nM). ATP or a P2X1,2,2/3 (α,β-MeATP) agonist evokes fast, slow, biphasic Ca(2+) transients or Ca(2+) oscillations (ATP,EC50 = 400 mM). PSCaTs are sensitive to P2X1 antagonist NF279. Low (20 nM) or high (5 µM) concentrations of P2X antagonist TNP-ATP block PSCaTs in different neurons; proportions of neurons with P2XR-immunoreactivity follow the order P2X2 > P2X1 >> P2X3; P2X1 + P2X2 and P2X3 + P2X2 are co-localized. RT-PCR identified mRNA-transcripts for P2X1-7, P2Y1,2,12-14R. CONCLUSIONS Purines are critical regulators of neurotransmission in human ENS. Purinergic signaling involves P2X1, P2X2, P2X3 channels, P2X1 + P2X2 co-localization and inhibitory P2Y or A3 receptors. These are potential novel therapeutic targets for neurogastroenterology.
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Affiliation(s)
- A Liñán-Rico
- Department of Anesthesiology, The Wexner Medical Center at The Ohio State University, Columbus, OH, USA
| | - J E Wunderlich
- Department of Anesthesiology, The Wexner Medical Center at The Ohio State University, Columbus, OH, USA
| | - J T Enneking
- Department of Anesthesiology, The Wexner Medical Center at The Ohio State University, Columbus, OH, USA
| | - D R Tso
- Department of Anesthesiology, The Wexner Medical Center at The Ohio State University, Columbus, OH, USA
| | - I Grants
- Department of Anesthesiology, The Wexner Medical Center at The Ohio State University, Columbus, OH, USA
| | - K C Williams
- Division of Pediatric Gastroenterology, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - A Otey
- Department of Anesthesiology, The Wexner Medical Center at The Ohio State University, Columbus, OH, USA
| | - K Michel
- Human Biology, Technische Universität München, Freising, Germany
| | - M Schemann
- Human Biology, Technische Universität München, Freising, Germany
| | - B Needleman
- Department of Surgery, The Wexner Medical Center at The Ohio State University, Columbus, OH, USA
| | - A Harzman
- Department of Surgery, The Wexner Medical Center at The Ohio State University, Columbus, OH, USA
| | - F L Christofi
- Department of Anesthesiology, The Wexner Medical Center at The Ohio State University, Columbus, OH, USA.
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Ostertag D, Buhner S, Michel K, Pehl C, Kurjak M, Götzberger M, Schulte-Frohlinde E, Frieling T, Enck P, Phillip J, Schemann M. Reduced Responses of Submucous Neurons from Irritable Bowel Syndrome Patients to a Cocktail Containing Histamine, Serotonin, TNFα, and Tryptase (IBS-Cocktail). Front Neurosci 2015; 9:465. [PMID: 26733780 PMCID: PMC4679876 DOI: 10.3389/fnins.2015.00465] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 11/23/2015] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND AND AIMS Malfunctions of enteric neurons are believed to play an important role in the pathophysiology of irritable bowel syndrome (IBS). Our aim was to investigate whether neuronal activity in biopsies from IBS patients is altered in comparison to healthy controls (HC). METHODS Activity of human submucous neurons in response to electrical nerve stimulation and local application of nicotine or a mixture of histamine, serotonin, tryptase, and TNF-α (IBS-cocktail) was recorded in biopsies from 17 HC and 35 IBS patients with the calcium-sensitive-dye Fluo-4 AM. The concentrations of the mediators resembeled those found in biopsy supernatants or blood. Neuronal activity in guinea-pig submucous neurons was studied with the voltage-sensitive-dye di-8-ANEPPS. RESULTS Activity in submucous ganglia in response to nicotine or electrical nerve stimulation was not different between HC and IBS patients (P = 0.097 or P = 0.448). However, the neuronal response after application of the IBS-cocktail was significantly decreased (P = 0.039) independent of whether diarrhea (n = 12), constipation (n = 5) or bloating (n = 5) was the predominant symptom. In agreement with this we found that responses of submucous ganglia conditioned by overnight incubation with IBS mucosal biopsy supernatant to spritz application of this supernatant was significantly reduced (P = 0.019) when compared to incubation with HC supernatant. CONCLUSION We demonstrated for the first time reduced neuronal responses in mucosal IBS biopsies to an IBS mediator cocktail. While excitability to classical stimuli of enteric neurons was comparable to HC, the activation by the IBS-cocktail was decreased. This was very likely due to desensitization to mediators constantly released by mucosal and immune cells in the gut wall of IBS patients.
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Affiliation(s)
| | - Sabine Buhner
- Human Biology, Technische Universität MünchenFreising, Germany
| | - Klaus Michel
- Human Biology, Technische Universität MünchenFreising, Germany
| | | | | | | | | | | | - Paul Enck
- Academic Hospital TübingenTübingen, Germany
| | | | - Michael Schemann
- Human Biology, Technische Universität MünchenFreising, Germany
- *Correspondence: Michael Schemann
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Mañé N, Gil V, Martínez-Cutillas M, Clavé P, Gallego D, Jiménez M. Differential functional role of purinergic and nitrergic inhibitory cotransmitters in human colonic relaxation. Acta Physiol (Oxf) 2014; 212:293-305. [PMID: 25327170 DOI: 10.1111/apha.12408] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 09/23/2014] [Accepted: 10/14/2014] [Indexed: 12/18/2022]
Abstract
AIM ATP and nitric oxide (NO) are released from enteric inhibitory motor neurones and are responsible for colonic smooth muscle relaxation. However, how frequency of neural stimulation affects this cotransmission process and the post-junctional responses has not been systematically characterized in the human colon. METHODS The dynamics of inhibitory cotransmission were studied using different protocols of electrical field stimulation (EFS) to characterize the inhibitory junction potentials (IJP) and the corresponding relaxation in colonic strips obtained from 36 patients. RESULTS Single pulses elicited a fast IJP (IJPf(MAX) = -27.6 ± 1.6 mV), sensitive to the P2Y1 antagonist MRS2500 1 μm, that ran down with frequency increase leaving a residual hyperpolarization at high frequencies (IJPf∞ = -3.7 ± 0.6 mV). Accordingly, low frequencies of EFS caused purinergic transient relaxations that cannot be maintained at high frequencies. Addition of the P2Y1 agonist MRS2365 10 μm during the purinergic rundown did not cause any hyperpolarization. Protein kinase C (PKC), a putative P2Y1 desensitizator, was able to reduce the amplitude of the IJPf when activated, but the rundown was not modified by PKC inhibitors. Frequencies higher than 0.60 ± 0.15 Hz were needed to evoke a sustained nitrergic hyperpolarization that progressively increased reaching IJPs∞ = -13 ± 0.4 mV at high frequencies and leading to a sustained inhibition of spontaneous motility. CONCLUSION Changes in frequency of stimulation possibly mimicking neuronal firing will post-junctionally determine purinergic vs. nitrergic responses underlying different functional roles. NO will be responsible for sustained relaxations needed in physiological processes such as storage, while purinergic neurotransmission evoking sharp transient relaxations will be dominant in processes such as propulsion.
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Affiliation(s)
- N. Mañé
- Department of Cell Biology, Physiology and Immunology and Neuroscience Institute; Universitat Autònoma de Barcelona; Barcelona Spain
| | - V. Gil
- Department of Cell Biology, Physiology and Immunology and Neuroscience Institute; Universitat Autònoma de Barcelona; Barcelona Spain
| | - M. Martínez-Cutillas
- Department of Cell Biology, Physiology and Immunology and Neuroscience Institute; Universitat Autònoma de Barcelona; Barcelona Spain
| | - P. Clavé
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd); Instituto de Salud Carlos III; Barcelona Spain
| | - D. Gallego
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd); Instituto de Salud Carlos III; Barcelona Spain
| | - M. Jiménez
- Department of Cell Biology, Physiology and Immunology and Neuroscience Institute; Universitat Autònoma de Barcelona; Barcelona Spain
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd); Instituto de Salud Carlos III; Barcelona Spain
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Martens MA, Boesmans W, Vanden Berghe P. Calcium imaging at kHz frame rates resolves millisecond timing in neuronal circuits and varicosities. BIOMEDICAL OPTICS EXPRESS 2014; 5:2648-2661. [PMID: 25136492 PMCID: PMC4132995 DOI: 10.1364/boe.5.002648] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 07/10/2014] [Accepted: 07/11/2014] [Indexed: 06/03/2023]
Abstract
We have configured a widefield fast imaging system that allows imaging at 1000 frames per second (512x512 pixels). The system was extended with custom processing tools including a time correlation method to facilitate the analysis of static subcellular compartments (e.g. neuronal varicosities) with enhanced contrast, as well as a dynamic intensity processing (DIP) algorithm that aids in data size reduction and fast visualization and interpretation of timing and directionality in neuronal circuits. This system, together with our custom developed processing tools enables efficient detection of fast physiological events, such as action potential dependent calcium steps. We show, using a specific blocker of nerve communication, that with this setup it is possible to discriminate between a pre and post synaptic event in an all optical way.
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Affiliation(s)
- Michiel A. Martens
- Laboratory for Enteric Neuroscience (LENS),TARGID, University of Leuven, O&N 1 Herestraat 49-box 701, Leuven 3000, Belgium
| | - Werend Boesmans
- Laboratory for Enteric Neuroscience (LENS),TARGID, University of Leuven, O&N 1 Herestraat 49-box 701, Leuven 3000, Belgium
| | - Pieter Vanden Berghe
- Laboratory for Enteric Neuroscience (LENS),TARGID, University of Leuven, O&N 1 Herestraat 49-box 701, Leuven 3000, Belgium
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28
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Buhner S, Braak B, Li Q, Kugler EM, Klooker T, Wouters M, Donovan J, Vignali S, Mazzuoli-Weber G, Grundy D, Boeckxstaens G, Schemann M. Neuronal activation by mucosal biopsy supernatants from irritable bowel syndrome patients is linked to visceral sensitivity. Exp Physiol 2014; 99:1299-311. [DOI: 10.1113/expphysiol.2014.080036] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Sabine Buhner
- Human Biology; Technische Universität München; Freising Germany
| | - Breg Braak
- Department of Gastroenterology and Hepatology; Academic Medical Center; Amsterdam The Netherlands
| | - Qin Li
- Human Biology; Technische Universität München; Freising Germany
- Department of Physiology; Shangdong University; Shangdong China
| | | | - Tamira Klooker
- Department of Gastroenterology and Hepatology; Academic Medical Center; Amsterdam The Netherlands
| | - Mira Wouters
- Translational Research Center for Gastrointestinal Disorders; University Hospital Gasthuisberg; Catholic University of Leuven; Leuven Belgium
| | - Jemma Donovan
- Department of Biomedical Science; University of Sheffield; Sheffield UK
| | - Sheila Vignali
- Human Biology; Technische Universität München; Freising Germany
| | | | - David Grundy
- Department of Biomedical Science; University of Sheffield; Sheffield UK
| | - Guy Boeckxstaens
- Department of Gastroenterology and Hepatology; Academic Medical Center; Amsterdam The Netherlands
- Translational Research Center for Gastrointestinal Disorders; University Hospital Gasthuisberg; Catholic University of Leuven; Leuven Belgium
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29
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Dynamics of inhibitory co-transmission, membrane potential and pacemaker activity determine neuromyogenic function in the rat colon. Pflugers Arch 2014; 466:2305-21. [DOI: 10.1007/s00424-014-1500-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 02/26/2014] [Accepted: 03/10/2014] [Indexed: 01/26/2023]
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30
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Simultaneous Multi-Wavelength Optical Imaging of Neuronal and Hemodynamic Activity. NEUROVASCULAR COUPLING METHODS 2014. [DOI: 10.1007/978-1-4939-0724-3_12] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Sia TC, Brookes SJ, Dinning PG, Wattchow DA, Spencer NJ. Peristalsis and propulsion of colonic content can occur after blockade of major neuroneuronal and neuromuscular transmitters in isolated guinea pig colon. Am J Physiol Gastrointest Liver Physiol 2013; 305:G933-9. [PMID: 24113766 DOI: 10.1152/ajpgi.00257.2013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We recently identified hexamethonium-resistant peristalsis in the guinea pig colon. We showed that, following acute blockade of nicotinic receptors, peristalsis recovers, leading to normal propagation velocities of fecal pellets along the colon. This raises the fundamental question: what mechanisms underlie hexamethonium-resistant peristalsis? We investigated whether blockade of the major receptors that underlie excitatory neuromuscular transmission is required for hexamethonium-resistant peristalsis. Video imaging of colonic wall movements was used to make spatiotemporal maps and determine the velocity of peristalsis. Propagation of artificial fecal pellets in the guinea pig distal colon was studied in hexamethonium, atropine, ω-conotoxin (GVIA), ibodutant (MEN-15596), and TTX. Hexamethonium and ibodutant alone did not retard peristalsis. In contrast, ω-conotoxin abolished peristalsis in some preparations and reduced the velocity of propagation in all remaining specimens. Peristalsis could still occur in some animals in the presence of hexamethonium + atropine + ibodutant + ω-conotoxin. Peristalsis never occurred in the presence of TTX. The major finding of the current study is the unexpected observation that peristalsis can occur after blockade of the major excitatory neuroneuronal and neuromuscular transmitters. Also, the colon retained an intrinsic polarity in the presence of these antagonists and was only able to expel pellets in an aboral direction. The nature of the mechanism(s)/neurotransmitter(s) that generate(s) peristalsis and facilitate(s) natural fecal pellet propulsion, after blockade of major excitatory neurotransmitters, at the neuroneuronal and neuromuscular junction remains to be identified.
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Affiliation(s)
- T C Sia
- Dept. of Human Physiology, School of Medicine, Flinders Univ., Adelaide, South Australia, Australia.
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Boesmans W, Martens MA, Weltens N, Hao MM, Tack J, Cirillo C, Vanden Berghe P. Imaging neuron-glia interactions in the enteric nervous system. Front Cell Neurosci 2013; 7:183. [PMID: 24155689 PMCID: PMC3801083 DOI: 10.3389/fncel.2013.00183] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Accepted: 10/01/2013] [Indexed: 12/13/2022] Open
Abstract
The enteric nervous system (ENS) is a network of neurons and glia within the wall of the gastrointestinal tract that is able to control many aspects of digestive function independently from the central nervous system. Enteric glial cells share several features with astrocytes and are closely associated with enteric neurons and their processes both within enteric ganglia, and along interconnecting fiber bundles. Similar to other parts of the nervous system, there is communication between enteric neurons and glia; enteric glial cells can detect neuronal activity and have the machinery to intermediate neurotransmission. However, due to the close contact between these two cell types and the particular characteristics of the gut wall, the recording of enteric glial cell activity in live imaging experiments, especially in the context of their interaction with neurons, is not straightforward. Most studies have used calcium imaging approaches to examine enteric glial cell activity but in many cases, it is difficult to distinguish whether observed transients arise from glial cells, or neuronal processes or varicosities in their vicinity. In this technical report, we describe a number of approaches to unravel the complex neuron-glia crosstalk in the ENS, focusing on the challenges and possibilities of live microscopic imaging in both animal models and human tissue samples.
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Affiliation(s)
- Werend Boesmans
- Laboratory for Enteric NeuroScience (LENS), Translational Research Center for GastroIntestinal Disorders, University of Leuven , Leuven, Belgium ; Translational Research Center for GastroIntestinal Disorders (TARGID), Department of Clinical and Experimental Medicine, University of Leuven , Leuven, Belgium
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Travis L, Spencer NJ. Imaging stretch-activated firing of spinal afferent nerve endings in mouse colon. Front Neurosci 2013; 7:179. [PMID: 24109427 PMCID: PMC3791392 DOI: 10.3389/fnins.2013.00179] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 09/17/2013] [Indexed: 11/13/2022] Open
Abstract
Spinal afferent neurons play a major role in detecting noxious and innocuous stimuli from visceral organs, such as the gastrointestinal tract. However, all our understanding about spinal afferents has been obtained from recordings of spinal afferent axons, or cell bodies that lie outside the gut wall, or peripheral organ they innervate. No recordings have been made directly from spinal afferent nerve endings, which is where sensory transduction occurs. We developed a preparation whereby recordings could be made from rectal afferent nerve endings in the colon, to characterize mechanisms underlying sensory transduction. Dorsal root ganglia (L6-S2) were removed from mice, whilst retaining neural continuity with the colon. Fluo-4-AM was used to record from rectal afferent nerve endings in myenteric ganglia and circular muscle at 36°C. In slack (unstretched) preparations of colon, no calcium transients were recorded from spinal afferent endings. However, in response to a maintained increase in circumferential diameter, a maintained discharge of calcium transients occurred simultaneously in multiple discrete varicosities along single axons of rectal afferents in myenteric ganglia and circular muscle. Stretch-activated calcium transients were resistant to hexamethonium and nifedipine, but were abolished by tetrodotoxin, CPA, BAPTA-AM, cobalt, gadolinium, or replacement of extracellular Na(+) with NMDG. In summary, we present a novel preparation in which stretch-activated firing of spinal afferent nerve endings can be recorded, using calcium imaging. We show that circumferential stretch of the colon activates a maintained discharge of calcium transients simultaneously in varicosities along single rectal afferent endings in myenteric ganglia and circular muscle. Non-selective cation channels, TTX-sensitive Na(+) channels and both extracellular calcium influx and intracellular Ca(2+) stores are required for stretch-activated calcium transients in rectal afferent endings.
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Affiliation(s)
- Lee Travis
- Discipline of Human Physiology, Center for Neuroscience, School of Medicine, Flinders University Bedford Park, SA, Australia
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Krueger D, Michel K, Allam S, Weiser T, Demir IE, Ceyhan GO, Zeller F, Schemann M. Effect of hyoscine butylbromide (Buscopan®) on cholinergic pathways in the human intestine. Neurogastroenterol Motil 2013; 25:e530-9. [PMID: 23682729 DOI: 10.1111/nmo.12156] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 04/23/2013] [Indexed: 12/12/2022]
Abstract
BACKGROUND Hyoscine butylbromide (HBB, Buscopan(®) ) is clinically used to treat intestinal cramps and visceral pain. Various studies, mainly on animal tissues, suggested that its antimuscarinic action is responsible for its spasmolytic effect. However, functional in vitro studies with human tissue have not been performed so far. METHODS We wanted to provide a comprehensive study on the mode of action of HBB in human intestinal samples and investigated HBB (1 nmol L(-1) -10 μmol L(-1)) effects on muscle activity with isometric force transducers and calcium imaging, on epithelial secretion with Ussing chamber technique and on enteric neurons using fast neuroimaging. KEY RESULTS Hyoscine butylbromide concentration dependently reduced muscle contractions, calcium mobilization, and epithelial secretion induced by the muscarinic agonist bethanechol with IC50 values of 429, 121, and 224 nmol L(-1), respectively. Forskolin-induced secretion was not altered by HBB. Cholinergic muscarinic muscle and epithelial responses evoked by electrical nerve stimulation were inhibited by 1-10 μmol L(-1) HBB. Moreover, HBB significantly reduced the bethanechol-induced action potential discharge in enteric neurons. Interestingly, we observed that high concentrations of HBB (10 μmol L(-1)) moderately decreased nicotinic receptor-mediated secretion, motility, and nerve activity. CONCLUSIONS & INFERENCES The results demonstrated the strong antimuscarinic action of HBB whereas the nicotinic antagonism at higher concentrations plays at most a moderate modulatory role. The muscle relaxing effect of HBB and its inhibition of muscarinic nerve activation likely explain its clinical use as an antispasmodic drug. Our results further highlight a so far unknown antisecretory action of HBB which warrants further clinical studies on its use in secretory disorders.
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Affiliation(s)
- D Krueger
- Human Biology, Technische Universität München, Freising, Germany
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Walstab J, Krüger D, Stark T, Hofmann T, Demir IE, Ceyhan GO, Feistel B, Schemann M, Niesler B. Ginger and its pungent constituents non-competitively inhibit activation of human recombinant and native 5-HT3 receptors of enteric neurons. Neurogastroenterol Motil 2013; 25:439-47, e302. [PMID: 23490018 DOI: 10.1111/nmo.12107] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Accepted: 02/05/2013] [Indexed: 02/08/2023]
Abstract
BACKGROUND Beneficial effects of ginger in the treatment of gastrointestinal (GI) problems and chemotherapy-induced nausea and vomiting are well accepted. In rodents, the action of ginger seems to be mediated by the inhibition of 5-HT3 receptors, which are established targets to combat emesis and irritable bowel syndrome. METHODS Heterologously expressed human 5-HT3 A or 5-HT3 AB receptors were characterized by means of Ca(2+) influx studies using HEK293 cells. Complementing Ca(2+) measurements in Fluo-4-AM-stained whole-mount preparations of the human submucous plexus were carried out. Furthermore, [3H]GR65630 binding assays were performed to reveal the mode of action of ginger and its pungent compounds. KEY RESULTS We show for the first time that ginger extracts and its pungent arylalkane constituents concentration-dependently inhibit activation of human 5-HT3 receptors. Ginger extracts inhibited both receptors with increasing content of pungent compounds, confirming that these are part of ginger's active principle. Inhibition potencies of the arylalkanes 6-gingerol and 6-shogaol on both receptors were in the low micromolar range. A lipophilic ginger extract and 6-gingerol had no influence on 5-HT potency, but reduced the 5-HT maximum effect, indicating non-competitive inhibition. The non-competitive action was confirmed by [(3) H]GR65630 binding, showing that the ginger extract did not displace the radioligand from 5-HT3 A and 5-HT3 AB receptors. The potential relevance of the inhibitory action of ginger on native 5-HT3 receptors in the gut was confirmed in whole-mount preparations of the human submucous plexus. While a general neurotoxic effect of 6-gingerol was ruled out, it inhibited the 2-methyl-5-HT-mediated activation of 5-HT3 receptors residing on enteric neurons. CONCLUSIONS & INFERENCES Our findings may encourage the use of ginger extracts to alleviate nausea in cancer patients receiving chemotherapy and to treat functional GI disorders.
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Affiliation(s)
- J Walstab
- Department of Human Molecular Genetics, Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany
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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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Schemann M, Kugler EM, Buhner S, Eastwood C, Donovan J, Jiang W, Grundy D. The mast cell degranulator compound 48/80 directly activates neurons. PLoS One 2012; 7:e52104. [PMID: 23272218 PMCID: PMC3525567 DOI: 10.1371/journal.pone.0052104] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Accepted: 11/09/2012] [Indexed: 11/18/2022] Open
Abstract
Background Compound 48/80 is widely used in animal and tissue models as a “selective” mast cell activator. With this study we demonstrate that compound 48/80 also directly activates enteric neurons and visceral afferents. Methodology/Principal Findings We used in vivo recordings from extrinsic intestinal afferents together with Ca++ imaging from primary cultures of DRG and nodose neurons. Enteric neuronal activation was examined by Ca++ and voltage sensitive dye imaging in isolated gut preparations and primary cultures of enteric neurons. Intraluminal application of compound 48/80 evoked marked afferent firing which desensitized on subsequent administration. In egg albumen-sensitized animals, intraluminal antigen evoked a similar pattern of afferent activation which also desensitized on subsequent exposure to antigen. In cross-desensitization experiments prior administration of compound 48/80 failed to influence the mast cell mediated response. Application of 1 and 10 µg/ml compound 48/80 evoked spike discharge and Ca++ transients in enteric neurons. The same nerve activating effect was observed in primary cultures of DRG and nodose ganglion cells. Enteric neuron cultures were devoid of mast cells confirmed by negative staining for c-kit or toluidine blue. In addition, in cultured enteric neurons the excitatory action of compound 48/80 was preserved in the presence of histamine H1 and H2 antagonists. The mast cell stabilizer cromolyn attenuated compound 48/80 and nicotine evoked Ca++ transients in mast cell-free enteric neuron cultures. Conclusions/Significance The results showed direct excitatory action of compound 48/80 on enteric neurons and visceral afferents. Therefore, functional changes measured in tissue or animal models may involve a mast cell independent effect of compound 48/80 and cromolyn.
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Affiliation(s)
- Michael Schemann
- Human Biology, Technische Universität München, Freising, Germany.
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Kugler EM, Mazzuoli G, Demir IE, Ceyhan GO, Zeller F, Schemann M. Activity of protease-activated receptors in primary cultured human myenteric neurons. Front Neurosci 2012; 6:133. [PMID: 22988431 PMCID: PMC3439632 DOI: 10.3389/fnins.2012.00133] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 08/26/2012] [Indexed: 12/19/2022] Open
Abstract
Activity of the four known protease-activated receptors (PARs) has been well studied in rodent enteric nervous system and results in animal models established an important role for neuronal PAR2. We recently demonstrated that, unlike in rodents, PAR1 is the dominant neuronal protease receptor in the human submucous plexus. With this study we investigated whether this also applies to the human myenteric plexus. We used voltage sensitive dye recordings to detect action potential discharge in primary cultures of human myenteric neurons in response to PAR activating peptides (APs). Application of the PAR1-AP (TFLLR) or PAR4-AP (GYPGQV) evoked spike discharge in 79 or 23% of myenteric neurons, respectively. The PAR1-AP response was mimicked by the endogenous PAR1 activator thrombin and blocked by the PAR1 antagonists SCH79797. Human myenteric neurons did not respond to PAR2-AP. This was not due to culture conditions because all three PAR-APs evoked action potentials in cultured guinea pig myenteric neurons. Consecutive application of PAR-APs revealed coexpression (relative to the population responding to PAR-APs) of PAR1/PAR2 in 51%, PAR1/PAR4 in 43%, and of PAR2/PAR4 in 29% of guinea pig myenteric neurons. Our study provided further evidence for the prominent role of neuronal PAR1 in the human enteric nervous system.
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Affiliation(s)
- Eva M Kugler
- Human Biology, Technische Universität München Freising, Germany
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Baudry C, Reichardt F, Marchix J, Bado A, Schemann M, des Varannes SB, Neunlist M, Moriez R. Diet-induced obesity has neuroprotective effects in murine gastric enteric nervous system: involvement of leptin and glial cell line-derived neurotrophic factor. J Physiol 2011; 590:533-44. [PMID: 22124147 DOI: 10.1113/jphysiol.2011.219717] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Nutritional factors can induce profound neuroplastic changes in the enteric nervous system (ENS), responsible for changes in gastrointestinal (GI) motility. However, long-term effects of a nutritional imbalance leading to obesity, such as Western diet (WD), upon ENS phenotype and control of GI motility remain unknown. Therefore, we investigated the effects of WD-induced obesity (DIO) on ENS phenotype and function as well as factors involved in functional plasticity. Mice were fed with normal diet (ND) or WD for 12 weeks. GI motility was assessed in vivo and ex vivo. Myenteric neurons and glia were analysed with immunohistochemical methods using antibodies against Hu, neuronal nitric oxide synthase (nNOS), Sox-10 and with calcium imaging techniques. Leptin and glial cell line-derived neurotrophic factor (GDNF) were studied using immunohistochemical, biochemical or PCR methods in mice and primary culture of ENS. DIO prevented the age-associated decrease in antral nitrergic neurons observed in ND mice. Nerve stimulation evoked a stronger neuronal Ca(2+) response in WD compared to ND mice. DIO induced an NO-dependent increase in gastric emptying and neuromuscular transmission in the antrum without any change in small intestinal transit. During WD but not ND, a time-dependent increase in leptin and GDNF occurred in the antrum. Finally, we showed that leptin increased GDNF production in the ENS and induced neuroprotective effects mediated in part by GDNF. These results demonstrate that DIO induces neuroplastic changes in the antrum leading to an NO-dependent acceleration of gastric emptying. In addition, DIO induced neuroplasticity in the ENS is likely to involve leptin and GDNF.
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Affiliation(s)
- Charlotte Baudry
- Inserm, U913, Institut F´ed´eratif de Recherche Th´erapeutique, IFR26 Nantes, France
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