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Mayr S, Elfers K, Mazzuoli-Weber G. The recruitment of mechanosensitive enteric neurons in the guinea pig gastric fundus is dependent on ganglionic stretch level. Neurogastroenterol Motil 2024; 36:e14858. [PMID: 38946168 DOI: 10.1111/nmo.14858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 05/23/2024] [Accepted: 06/20/2024] [Indexed: 07/02/2024]
Abstract
BACKGROUND Serving as a reservoir, the gastric fundus can expand significantly, with an initial receptive and a following adaptive relaxation, controlled by extrinsic and intrinsic reflex circuits, respectively. We hypothesize that mechanosensitive enteric neurons (MEN) are involved in the adaptive relaxation, which is initiated when a particular gastric volume and a certain stretch of the stomach wall is reached. To investigate whether the responsiveness of MEN in the gastric fundus is dependent on tissue stretch, we performed mechanical stimulations in stretched versus ganglia "at rest". METHODS Responses of myenteric neurons in the guinea pig gastric fundus were recorded with membrane potential imaging using Di-8-ANEPPS. MEN were identified by small-volume intraganglionic injection in ganglia stretched to different degrees using a self-constructed stretching tool. Immunohistochemical staining identified the neurochemical phenotype of MEN. Hexamethonium and capsaicin were added to test their effect on recruited MEN. KEY RESULTS In stretched compared to "at rest" ganglia, significantly more MEN were activated. The change in the ganglionic area correlated significantly with the number of additional recruited MEN. The additional recruitment of MEN was independent from nicotinic transmission and the ratio of active MEN in stretched ganglia shifted towards a nitrergic phenotype. CONCLUSION AND INFERENCES The higher number of active MEN with increasing stretch of the ganglia and their greater share of nitrergic phenotype might indicate their contribution to the adaptive relaxation. Further experiments are necessary to address the receptors involved in mechanotransduction.
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Affiliation(s)
- Sophia Mayr
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
| | - Kristin Elfers
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Gemma Mazzuoli-Weber
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
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2
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Zhao C, Zhou X, Shi X. The influence of Nav1.9 channels on intestinal hyperpathia and dysmotility. Channels (Austin) 2023; 17:2212350. [PMID: 37186898 DOI: 10.1080/19336950.2023.2212350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023] Open
Abstract
The Nav1.9 channel is a voltage-gated sodium channel. It plays a vital role in the generation of pain and the formation of neuronal hyperexcitability after inflammation. It is highly expressed in small diameter neurons of dorsal root ganglions and Dogiel II neurons in enteric nervous system. The small diameter neurons in dorsal root ganglions are the primary sensory neurons of pain conduction. Nav1.9 channels also participate in regulating intestinal motility. Functional enhancements of Nav1.9 channels to a certain extent lead to hyperexcitability of small diameter dorsal root ganglion neurons. The hyperexcitability of the neurons can cause visceral hyperalgesia. Intestinofugal afferent neurons and intrinsic primary afferent neurons in enteric nervous system belong to Dogiel type II neurons. Their excitability can also be regulated by Nav1.9 channels. The hyperexcitability of intestinofugal afferent neurons abnormally activate entero-enteric inhibitory reflexes. The hyperexcitability of intrinsic primary afferent neurons disturb peristaltic waves by abnormally activating peristaltic reflexes. This review discusses the role of Nav1.9 channels in intestinal hyperpathia and dysmotility.
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Affiliation(s)
- Chenyu Zhao
- Department of Gastroenterology, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Zhengzhou, China
- Department of Gastroenterology, The Second Xiangya Hospital, Central South University, Changsha, China
- Department of Medical Genetics, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Xi Zhou
- The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China
| | - Xiaoliu Shi
- Department of Medical Genetics, The Second Xiangya Hospital, Central South University, Changsha, China
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3
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Barth BB, Redington ER, Gautam N, Pelot NA, Grill WM. Calcium image analysis in the moving gut. Neurogastroenterol Motil 2023; 35:e14678. [PMID: 37736662 PMCID: PMC10999186 DOI: 10.1111/nmo.14678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 08/14/2023] [Accepted: 08/28/2023] [Indexed: 09/23/2023]
Abstract
BACKGROUND The neural control of gastrointestinal muscle relies on circuit activity whose underlying motifs remain limited by small-sample calcium imaging recordings confounded by motion artifact, paralytics, and muscle dissections. We present a sequence of resources to register images from moving preparations and identify out-of-focus events in widefield fluorescent microscopy. METHODS Our algorithm uses piecewise rigid registration with pathfinding to correct movements associated with smooth muscle contractions. We developed methods to identify loss-of-focus events and to simulate calcium activity to evaluate registration. KEY RESULTS By combining our methods with principal component analysis, we found populations of neurons exhibit distinct activity patterns in response to distinct stimuli consistent with hypothesized roles. The image analysis pipeline makes deeper insights possible by capturing concurrently calcium dynamics from more neurons in larger fields of view. We provide access to the source code for our algorithms and make experimental and technical recommendations to increase data quality in calcium imaging experiments. CONCLUSIONS These methods make feasible large population, robust calcium imaging recordings and permit more sophisticated network analyses and insights into neural activity patterns in the gut.
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Affiliation(s)
- Bradley B. Barth
- Department of Biomedical Engineering, Duke University, Durham, NC 27708
| | - Emily R. Redington
- Department of Biomedical Engineering, Duke University, Durham, NC 27708
- Current employment Regeneron Pharmaceuticals, Inc. Contributions to this article were made as an employee of Duke University and the views expressed do not necessarily represent the views of Regeneron Pharmaceuticals Inc
| | - Nitisha Gautam
- Department of Biomedical Engineering, Duke University, Durham, NC 27708
| | - Nicole A. Pelot
- Department of Biomedical Engineering, Duke University, Durham, NC 27708
| | - Warren M. Grill
- Department of Biomedical Engineering, Duke University, Durham, NC 27708
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4
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Mayr S, Schliep R, Elfers K, Mazzuoli-Weber G. Mechanosensitive enteric neurons in the guinea pig gastric fundus and antrum. Neurogastroenterol Motil 2023; 35:e14674. [PMID: 37702071 DOI: 10.1111/nmo.14674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 07/16/2023] [Accepted: 08/28/2023] [Indexed: 09/14/2023]
Abstract
BACKGROUND Coping with the ingested food, the gastric regions of fundus, corpus, and antrum display different motility patterns. Intrinsic components of such patterns involving mechanosensitive enteric neurons (MEN) have been described in the guinea pig gastric corpus but are poorly understood in the fundus and antrum. METHODS To elucidate mechanosensitive properties of myenteric neurons in the gastric fundus and antrum, membrane potential imaging using Di-8-ANEPPS was applied. A small-volume injection led to neuronal compression. We analyzed the number of MEN and their firing frequency in addition to the involvement of selected mechanoreceptors. To characterize the neurochemical phenotype of MEN, we performed immunohistochemistry. KEY RESULTS In the gastric fundus, 16% of the neurons reproducibly responded to mechanical stimulation and thus were MEN. Of those, 83% were cholinergic and 19% nitrergic. In the antrum, 6% of the neurons responded to the compression stimulus, equally distributed among cholinergic and nitrergic MEN. Defunctionalizing the sensory extrinsic afferents led to a significant drop in the number of MEN in both regions. CONCLUSION We provided evidence for MEN in the gastric fundus and antrum and further investigated mechanoreceptors. However, the proportions of the chemical phenotypes of the MEN differed significantly between both regions. Further investigations of synaptic connections of MEN are crucial to understand the hardwired neuronal circuits in the stomach.
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Affiliation(s)
- Sophia Mayr
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
| | - Ronja Schliep
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Kristin Elfers
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Gemma Mazzuoli-Weber
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
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5
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Sharkey KA, Mawe GM. The enteric nervous system. Physiol Rev 2023; 103:1487-1564. [PMID: 36521049 PMCID: PMC9970663 DOI: 10.1152/physrev.00018.2022] [Citation(s) in RCA: 58] [Impact Index Per Article: 58.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 12/12/2022] [Accepted: 12/15/2022] [Indexed: 12/23/2022] Open
Abstract
Of all the organ systems in the body, the gastrointestinal tract is the most complicated in terms of the numbers of structures involved, each with different functions, and the numbers and types of signaling molecules utilized. The digestion of food and absorption of nutrients, electrolytes, and water occurs in a hostile luminal environment that contains a large and diverse microbiota. At the core of regulatory control of the digestive and defensive functions of the gastrointestinal tract is the enteric nervous system (ENS), a complex system of neurons and glia in the gut wall. In this review, we discuss 1) the intrinsic neural control of gut functions involved in digestion and 2) how the ENS interacts with the immune system, gut microbiota, and epithelium to maintain mucosal defense and barrier function. We highlight developments that have revolutionized our understanding of the physiology and pathophysiology of enteric neural control. These include a new understanding of the molecular architecture of the ENS, the organization and function of enteric motor circuits, and the roles of enteric glia. We explore the transduction of luminal stimuli by enteroendocrine cells, the regulation of intestinal barrier function by enteric neurons and glia, local immune control by the ENS, and the role of the gut microbiota in regulating the structure and function of the ENS. Multifunctional enteric neurons work together with enteric glial cells, macrophages, interstitial cells, and enteroendocrine cells integrating an array of signals to initiate outputs that are precisely regulated in space and time to control digestion and intestinal homeostasis.
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Affiliation(s)
- Keith A Sharkey
- Hotchkiss Brain Institute and Snyder Institute for Chronic Diseases, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Gary M Mawe
- Department of Neurological Sciences, Larner College of Medicine, University of Vermont, Burlington, Vermont
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6
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Elfers K, Schäuffele S, Hoppe S, Michel K, Zeller F, Demir IE, Schemann M, Mazzuoli-Weber G. Distension evoked mucosal secretion in human and porcine colon in vitro. PLoS One 2023; 18:e0282732. [PMID: 37053302 PMCID: PMC10101454 DOI: 10.1371/journal.pone.0282732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 02/20/2023] [Indexed: 04/15/2023] Open
Abstract
It was suggested that intestinal mucosal secretion is enhanced during muscle relaxation and contraction. Mechanisms of mechanically induced secretion have been studied in rodent species. We used voltage clamp Ussing technique to investigate, in human and porcine colonic tissue, secretion evoked by serosal (Pser) or mucosal (Pmuc) pressure application (2-60 mmHg) to induce distension into the mucosal or serosal compartment, respectively. In both species, Pser or Pmuc caused secretion due to Cl- and, in human colon, also HCO3- fluxes. In the human colon, responses were larger in proximal than distal regions. In porcine colon, Pmuc evoked larger responses than Pser whereas the opposite was the case in human colon. In both species, piroxicam revealed a strong prostaglandin (PG) dependent component. Pser and Pmuc induced secretion was tetrodotoxin (TTX) sensitive in porcine colon. In human colon, a TTX sensitive component was only revealed after piroxicam. However, synaptic blockade by ω-conotoxin GVIA reduced the response to mechanical stimuli. Secretion was induced by tensile rather than compressive forces as preventing distension by a filter inhibited the secretion. In conclusion, in both species, distension induced secretion was predominantly mediated by PGs and a rather small nerve dependent response involving mechanosensitive somata and synapses.
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Affiliation(s)
- Kristin Elfers
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Hannover, Germany
| | | | - Susanne Hoppe
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Klaus Michel
- Chair of Human Biology, Technical University of Munich, Freising, Germany
| | | | - Ihsan Ekin Demir
- University Hospital Rechts der Isar, Technical University of Munich, München, 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 Hannover, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
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7
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Kola JB, Docsa T, Uray K. Mechanosensing in the Physiology and Pathology of the Gastrointestinal Tract. Int J Mol Sci 2022; 24:ijms24010177. [PMID: 36613619 PMCID: PMC9820522 DOI: 10.3390/ijms24010177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 12/10/2022] [Accepted: 12/17/2022] [Indexed: 12/24/2022] Open
Abstract
Normal gastrointestinal function relies on sensing and transducing mechanical signals into changes in intracellular signaling pathways. Both specialized mechanosensing cells, such as certain enterochromaffin cells and enteric neurons, and non-specialized cells, such as smooth muscle cells, interstitial cells of Cajal, and resident macrophages, participate in physiological and pathological responses to mechanical signals in the gastrointestinal tract. We review the role of mechanosensors in the different cell types of the gastrointestinal tract. Then, we provide several examples of the role of mechanotransduction in normal physiology. These examples highlight the fact that, although these responses to mechanical signals have been known for decades, the mechanosensors involved in these responses to mechanical signals are largely unknown. Finally, we discuss several diseases involving the overstimulation or dysregulation of mechanotransductive pathways. Understanding these pathways and identifying the mechanosensors involved in these diseases may facilitate the identification of new drug targets to effectively treat these diseases.
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Affiliation(s)
- Job Baffin Kola
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Center of Excellence, The Hungarian Academy of Sciences, 4032 Debrecen, Hungary
| | - Tibor Docsa
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Center of Excellence, The Hungarian Academy of Sciences, 4032 Debrecen, Hungary
| | - Karen Uray
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Center of Excellence, The Hungarian Academy of Sciences, 4032 Debrecen, Hungary
- Correspondence:
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8
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Li Z, Boesmans W, Kazwiny Y, Hao MM, Vanden Berghe P. Simultaneous whole-cell patch-clamp and calcium imaging on myenteric neurons. Am J Physiol Gastrointest Liver Physiol 2022; 323:G341-G347. [PMID: 36044672 DOI: 10.1152/ajpgi.00162.2022] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Live calcium imaging is often used as a proxy for electrophysiological measurements and has been a valuable tool that allows simultaneous analysis of neuronal activity in multiple cells at the population level. In the enteric nervous system, there are two main electrophysiological classes of neurons, after-hyperpolarizing (AH)- and synaptic (S)-neurons, which have been shown to have different calcium handling mechanisms. However, they are rarely considered separately in calcium imaging experiments. A handful of studies have shown that in guinea pig, a calcium transient will accompany a single action potential in AH-neurons, but multiple action potentials are required to generate a calcium transient in S-neurons. How this translates to different modes of cellular depolarization and whether this is consistent across species is unknown. In this study, we used simultaneous whole-cell patch-clamp electrophysiology together with calcium imaging to investigate how enteric neurons respond to different modes of depolarization. Using both traditional (4 Hz) and also high-speed (1,000 Hz) imaging techniques, we found that single action potentials elicit calcium transients in both AH-neurons and S-neurons. Subthreshold membrane depolarizations were also able to elicit calcium transients, although calcium responses were generally amplified if an action potential was present. Furthermore, we identified that responses to nicotinic acetylcholine receptor stimulation can be used to distinguish between AH- and S-neurons in calcium imaging.NEW & NOTEWORTHY Live calcium imaging is an important tool for investigating enteric nervous system (ENS) function. Previous studies have shown that multiple action potentials are needed to generate a calcium response in S-neurons, which has important implications for the interpretation of calcium imaging data. Here, we show that in mouse myenteric neurons, calcium transients are elicited by single action potentials in both AH- and S-neurons. In addition, nicotinic acetylcholine receptor stimulation can be used to distinguish between these two classes.
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Affiliation(s)
- Zhiling Li
- Laboratory for Enteric Neuroscience, Translational Research Center for Gastrointestinal Disorders, ChroMeta, Katholieke Universiteit Leuven, Leuven, Belgium.,The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, People's Republic of China
| | - Werend Boesmans
- Biomedical Research Institute, Hasselt University, Hasselt, Belgium.,Department of Pathology, GROW-School for Oncology and Reproduction, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Youcef Kazwiny
- Laboratory for Enteric Neuroscience, Translational Research Center for Gastrointestinal Disorders, ChroMeta, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Marlene M Hao
- Laboratory for Enteric Neuroscience, Translational Research Center for Gastrointestinal Disorders, ChroMeta, Katholieke Universiteit Leuven, Leuven, Belgium.,Department of Anatomy and Physiology, The University of Melbourne, Parkville, Victoria, Australia
| | - Pieter Vanden Berghe
- Laboratory for Enteric Neuroscience, Translational Research Center for Gastrointestinal Disorders, ChroMeta, Katholieke Universiteit Leuven, Leuven, Belgium.,Leuven Brain Institute, Katholieke Universiteit Leuven, Leuven, Belgium
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9
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Yang H, Hou C, Xiao W, Qiu Y. The role of mechanosensitive ion channels in the gastrointestinal tract. Front Physiol 2022; 13:904203. [PMID: 36060694 PMCID: PMC9437298 DOI: 10.3389/fphys.2022.904203] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 07/19/2022] [Indexed: 11/13/2022] Open
Abstract
Mechanosensation is essential for normal gastrointestinal (GI) function, and abnormalities in mechanosensation are associated with GI disorders. There are several mechanosensitive ion channels in the GI tract, namely transient receptor potential (TRP) channels, Piezo channels, two-pore domain potassium (K2p) channels, voltage-gated ion channels, large-conductance Ca2+-activated K+ (BKCa) channels, and the cystic fibrosis transmembrane conductance regulator (CFTR). These channels are located in many mechanosensitive intestinal cell types, namely enterochromaffin (EC) cells, interstitial cells of Cajal (ICCs), smooth muscle cells (SMCs), and intrinsic and extrinsic enteric neurons. In these cells, mechanosensitive ion channels can alter transmembrane ion currents in response to mechanical forces, through a process known as mechanoelectrical coupling. Furthermore, mechanosensitive ion channels are often associated with a variety of GI tract disorders, including irritable bowel syndrome (IBS) and GI tumors. Mechanosensitive ion channels could therefore provide a new perspective for the treatment of GI diseases. This review aims to highlight recent research advances regarding the function of mechanosensitive ion channels in the GI tract. Moreover, it outlines the potential role of mechanosensitive ion channels in related diseases, while describing the current understanding of interactions between the GI tract and mechanosensitive ion channels.
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Affiliation(s)
- Haoyu Yang
- Experimental Center of Basic Medicine, College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Chaofeng Hou
- Experimental Center of Basic Medicine, College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Weidong Xiao
- Department of General Surgery, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Yuan Qiu
- Department of General Surgery, Xinqiao Hospital, Army Medical University, Chongqing, China
- *Correspondence: Yuan Qiu,
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10
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Mercado-Perez A, Beyder A. Gut feelings: mechanosensing in the gastrointestinal tract. Nat Rev Gastroenterol Hepatol 2022; 19:283-296. [PMID: 35022607 PMCID: PMC9059832 DOI: 10.1038/s41575-021-00561-y] [Citation(s) in RCA: 48] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/22/2021] [Indexed: 12/11/2022]
Abstract
The primary function of the gut is to procure nutrients. Synchronized mechanical activities underlie nearly all its endeavours. Coordination of mechanical activities depends on sensing of the mechanical forces, in a process called mechanosensation. The gut has a range of mechanosensory cells. They function either as specialized mechanoreceptors, which convert mechanical stimuli into coordinated physiological responses at the organ level, or as non-specialized mechanosensory cells that adjust their function based on the mechanical state of their environment. All major cell types in the gastrointestinal tract contain subpopulations that act as specialized mechanoreceptors: epithelia, smooth muscle, neurons, immune cells, and others. These cells are tuned to the physical properties of the surrounding tissue, so they can discriminate mechanical stimuli from the baseline mechanical state. The importance of gastrointestinal mechanosensation has long been recognized, but the latest discoveries of molecular identities of mechanosensors and technical advances that resolve the relevant circuitry have poised the field to make important intellectual leaps. This Review describes the mechanical factors relevant for normal function, as well as the molecules, cells and circuits involved in gastrointestinal mechanosensing. It concludes by outlining important unanswered questions in gastrointestinal mechanosensing.
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Affiliation(s)
- Arnaldo Mercado-Perez
- Enteric NeuroScience Program (ENSP), Division of Gastroenterology & Hepatology, Mayo Clinic, Rochester, MN, USA
- Medical Scientist Training Program (MSTP), Mayo Clinic, Rochester, MN, USA
| | - Arthur Beyder
- Enteric NeuroScience Program (ENSP), Division of Gastroenterology & Hepatology, Mayo Clinic, Rochester, MN, USA.
- Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, MN, USA.
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11
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Feng J, Hibberd TJ, Luo J, Yang P, Xie Z, Travis L, Spencer NJ, Hu H. Modification of Neurogenic Colonic Motor Behaviours by Chemogenetic Ablation of Calretinin Neurons. Front Cell Neurosci 2022; 16:799717. [PMID: 35317196 PMCID: PMC8934436 DOI: 10.3389/fncel.2022.799717] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 01/31/2022] [Indexed: 12/31/2022] Open
Abstract
How the enteric nervous system determines the pacing and propagation direction of neurogenic contractions along the colon remains largely unknown. We used a chemogenetic strategy to ablate enteric neurons expressing calretinin (CAL). Mice expressing human diphtheria toxin receptor (DTR) in CAL neurons were generated by crossing CAL-ires-Cre mice with Cre-dependent ROSA26-DTR mice. Immunohistochemical analysis revealed treatment with diphtheria toxin incurred a 42% reduction in counts of Hu-expressing colonic myenteric neurons (P = 0.036), and 57% loss of CAL neurons (comprising ∼25% of all Hu neurons; P = 0.004) compared to control. As proportions of Hu-expressing neurons, CAL neurons that contained nitric oxide synthase (NOS) were relatively spared (control: 15 ± 2%, CAL-DTR: 13 ± 1%; P = 0.145), while calretinin neurons lacking NOS were significantly reduced (control: 26 ± 2%, CAL-DTR: 18 ± 5%; P = 0.010). Colonic length and pellet sizes were significantly reduced without overt inflammation or changes in ganglionic density. Interestingly, colonic motor complexes (CMCs) persisted with increased frequency (mid-colon interval 111 ± 19 vs. 189 ± 24 s, CAL-DTR vs. control, respectively, P < 0.001), decreased contraction size (mid-colon AUC 26 ± 24 vs. 59 ± 13 gram/seconds, CAL-DTR vs. control, respectively, P < 0.001), and lacked preferential anterograde migration (P < 0.001). The functional effects of modest calretinin neuron ablation, particularly increased neurogenic motor activity frequencies, differ from models that incur general enteric neuron loss, and suggest calretinin neurons may contribute to pacing, force, and polarity of CMCs in the large bowel.
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Affiliation(s)
- Jing Feng
- Center for the Study of Itch and Sensory Disorders, Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, United States
- Center for Neurological and Psychiatric Research and Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Tim J. Hibberd
- College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Adelaide, SA, Australia
| | - Jialie Luo
- Center for the Study of Itch and Sensory Disorders, Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, United States
| | - Pu Yang
- Center for the Study of Itch and Sensory Disorders, Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, United States
| | - Zili Xie
- Center for the Study of Itch and Sensory Disorders, Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, United States
| | - Lee Travis
- College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Adelaide, SA, Australia
| | - Nick J. Spencer
- College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Adelaide, SA, Australia
- *Correspondence: Nick J. Spencer,
| | - Hongzhen Hu
- Center for the Study of Itch and Sensory Disorders, Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, United States
- Hongzhen Hu,
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12
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Mazzuoli-Weber G. Mechanosensitive Enteric Neurons (MEN) at Work. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1383:45-53. [PMID: 36587145 DOI: 10.1007/978-3-031-05843-1_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
In the last decade, we characterized an enteric neuronal subpopulation of multifunctional mechanosensitive enteric neurons (MEN) while studying the gastrointestinal peristalsis. MEN have been described in a variety of gastrointestinal regions and species. This chapter summarizes existing data on MEN, describing their proportions, firing behaviors, adaptation musters, and chemical phenotypes. We also discuss MEN sensitivity to different mechanical stimulus qualities such as compression and tension along with pharmacology of their responses.
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Affiliation(s)
- Gemma Mazzuoli-Weber
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany.
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13
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Howard MJ. Refining Enteric Neural Circuitry by Quantitative Morphology and Function in Mice. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1383:213-219. [PMID: 36587160 DOI: 10.1007/978-3-031-05843-1_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
RNA-Seq, electrophysiology and optogenetics in mouse models are used to assess function, identify disease related genes and model enteric neural circuits. Lacking a comprehensive quantitative description of the murine colonic enteric nervous system (ENS) makes it difficult to most effectively use mouse data to better understand ENS function or for development of therapeutic approaches for human motility disorders. Our goal was to provide a quantitative description of mouse colon to establish the extent to which mouse colon architecture, connectivity and function is a useful surrogate for human and other mammalian ENS. Using GCaMP imaging coupled with pharmacology and quantitative confocal and 3D image reconstruction, we present quantitative and functional data demonstrating that regional structural changes and variable distribution of neurons define neural circuit dynamics and functional connectivity responsible for colonic motor patterns and regional functional differences. Our results advance utility of multispecies and gut region-specific data.
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Affiliation(s)
- Marthe J Howard
- University of Toledo, College of Medicine and Life Sciences, Toledo, OH, USA.
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Barth BB, Spencer NJ, Grill WM. Activation of ENS Circuits in Mouse Colon: Coordination in the Mouse Colonic Motor Complex as a Robust, Distributed Control System. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1383:113-123. [PMID: 36587151 DOI: 10.1007/978-3-031-05843-1_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The characteristic motor patterns of the colon are coordinated by the enteric nervous system (ENS) and involve enterochromaffin (EC) cells, enteric glia, smooth muscle fibers, and interstitial cells. While the fundamental control mechanisms of colonic motor patterns are understood, greater complexity in the circuitry underlying motor patterns has been revealed by recent advances in the field. We review these recent advances and new findings from our laboratories that provide insights into how the ENS coordinates motor patterns in the isolated mouse colon. We contextualize these observations by describing the neuromuscular system underling the colonic motor complex (CMC) as a robust, distributed control system. Framing the colonic motor complex as a control system reveals a new perspective on the coordinated motor patterns in the colon. We test the control system by applying electrical stimulation in the isolated mouse colon to disrupt the coordination and propagation of the colonic motor complex.
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Affiliation(s)
- Bradley B Barth
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Nick J Spencer
- College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, NC, USA.
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15
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Enteric Control of the Sympathetic Nervous System. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1383:89-103. [PMID: 36587149 DOI: 10.1007/978-3-031-05843-1_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The autonomic nervous system that regulates the gut is divided into sympathetic (SNS), parasympathetic (PNS), and enteric nervous systems (ENS). They inhibit, permit, and coordinate gastrointestinal motility, respectively. A fourth pathway, "extrinsic sensory neurons," connect gut to the central nervous system, mediating sensation. The ENS resides within the gut wall and its activities are critical for life; ENS failure to populate the gut in development is lethal without intervention."Viscerofugal neurons" are a distinctive class of enteric neurons, being the only type that escapes the gut wall. They form a unique circuit: their axons project out of the gut wall and activate sympathetic neurons, which then project back to the gut, and inhibit gut movements.For 80 years viscerofugal/sympathetic circuits were thought to have a restricted role, mediating simple sensory-motor reflexes. New data shows viscerofugal and sympathetic neurons behaving unexpectedly, compelling a re-evaluation of these circuits: both viscerofugal and sympathetic neurons transmit higher order, synchronized firing patterns that originate within the ENS. This identifies them as driving long-range motility control between different gut regions.There is need for gut motor control over distances beyond the range of ENS circuits, yet no mechanism has been identified to date. The entero-sympathetic circuits are ideally suited to meet this need. Here we provide an overview of the structure and functions of these peripheral sympathetic circuits, including new data showing the firing patterns generated by enteric networks can transmit through sympathetic neurons.
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16
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Wright CM, Schneider S, Smith-Edwards KM, Mafra F, Leembruggen AJL, Gonzalez MV, Kothakapa DR, Anderson JB, Maguire BA, Gao T, Missall TA, Howard MJ, Bornstein JC, Davis BM, Heuckeroth RO. scRNA-Seq Reveals New Enteric Nervous System Roles for GDNF, NRTN, and TBX3. Cell Mol Gastroenterol Hepatol 2021; 11:1548-1592.e1. [PMID: 33444816 PMCID: PMC8099699 DOI: 10.1016/j.jcmgh.2020.12.014] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 12/24/2020] [Accepted: 12/30/2020] [Indexed: 02/07/2023]
Abstract
BACKGROUND AND AIMS Bowel function requires coordinated activity of diverse enteric neuron subtypes. Our aim was to define gene expression in these neuron subtypes to facilitate development of novel therapeutic approaches to treat devastating enteric neuropathies, and to learn more about enteric nervous system function. METHODS To identify subtype-specific genes, we performed single-nucleus RNA-seq on adult mouse and human colon myenteric plexus, and single-cell RNA-seq on E17.5 mouse ENS cells from whole bowel. We used immunohistochemistry, select mutant mice, and calcium imaging to validate and extend results. RESULTS RNA-seq on 635 adult mouse colon myenteric neurons and 707 E17.5 neurons from whole bowel defined seven adult neuron subtypes, eight E17.5 neuron subtypes and hundreds of differentially expressed genes. Manually dissected human colon myenteric plexus yielded RNA-seq data from 48 neurons, 3798 glia, 5568 smooth muscle, 377 interstitial cells of Cajal, and 2153 macrophages. Immunohistochemistry demonstrated differential expression for BNC2, PBX3, SATB1, RBFOX1, TBX2, and TBX3 in enteric neuron subtypes. Conditional Tbx3 loss reduced NOS1-expressing myenteric neurons. Differential Gfra1 and Gfra2 expression coupled with calcium imaging revealed that GDNF and neurturin acutely and differentially regulate activity of ∼50% of myenteric neurons with distinct effects on smooth muscle contractions. CONCLUSION Single cell analyses defined genes differentially expressed in myenteric neuron subtypes and new roles for TBX3, GDNF and NRTN. These data facilitate molecular diagnostic studies and novel therapeutics for bowel motility disorders.
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Affiliation(s)
- Christina M Wright
- Department of Pediatrics, Abramson Research Center, Children's Hospital of Philadelphia Research Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Sabine Schneider
- Department of Pediatrics, Abramson Research Center, Children's Hospital of Philadelphia Research Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Kristen M Smith-Edwards
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, Pennsylvania; Center for Neuroscience at the University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Fernanda Mafra
- Center for Applied Genomics, Abramson Research Center, Children's Hospital of Philadelphia Research Institute, Philadelphia, Pennsylvania
| | | | - Michael V Gonzalez
- Center for Applied Genomics, Abramson Research Center, Children's Hospital of Philadelphia Research Institute, Philadelphia, Pennsylvania
| | - Deepika R Kothakapa
- Department of Pediatrics, Abramson Research Center, Children's Hospital of Philadelphia Research Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jessica B Anderson
- Department of Pediatrics, Abramson Research Center, Children's Hospital of Philadelphia Research Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Beth A Maguire
- Department of Pediatrics, Abramson Research Center, Children's Hospital of Philadelphia Research Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Tao Gao
- Department of Pediatrics, Abramson Research Center, Children's Hospital of Philadelphia Research Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Tricia A Missall
- Department of Dermatology, University of Florida, Gainesville, Florida
| | - Marthe J Howard
- Department of Neurosciences, University of Toledo Health Sciences Campus, Toledo, Ohio
| | - Joel C Bornstein
- Department of Physiology, University of Melbourne, Parkville, Victoria, Australia
| | - Brian M Davis
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, Pennsylvania; Center for Neuroscience at the University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Robert O Heuckeroth
- Department of Pediatrics, Abramson Research Center, Children's Hospital of Philadelphia Research Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.
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17
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Fang XZ, Zhou T, Xu JQ, Wang YX, Sun MM, He YJ, Pan SW, Xiong W, Peng ZK, Gao XH, Shang Y. Structure, kinetic properties and biological function of mechanosensitive Piezo channels. Cell Biosci 2021; 11:13. [PMID: 33422128 PMCID: PMC7796548 DOI: 10.1186/s13578-020-00522-z] [Citation(s) in RCA: 96] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 12/16/2020] [Indexed: 02/06/2023] Open
Abstract
Mechanotransduction couples mechanical stimulation with ion flux, which is critical for normal biological processes involved in neuronal cell development, pain sensation, and red blood cell volume regulation. Although they are key mechanotransducers, mechanosensitive ion channels in mammals have remained difficult to identify. In 2010, Coste and colleagues revealed a novel family of mechanically activated cation channels in eukaryotes, consisting of Piezo1 and Piezo2 channels. These have been proposed as the long-sought-after mechanosensitive cation channels in mammals. Piezo1 and Piezo2 exhibit a unique propeller-shaped architecture and have been implicated in mechanotransduction in various critical processes, including touch sensation, balance, and cardiovascular regulation. Furthermore, several mutations in Piezo channels have been shown to cause multiple hereditary human disorders, such as autosomal recessive congenital lymphatic dysplasia. Notably, mutations that cause dehydrated hereditary xerocytosis alter the rate of Piezo channel inactivation, indicating the critical role of their kinetics in normal physiology. Given the importance of Piezo channels in understanding the mechanotransduction process, this review focuses on their structural details, kinetic properties and potential function as mechanosensors. We also briefly review the hereditary diseases caused by mutations in Piezo genes, which is key for understanding the function of these proteins.
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Affiliation(s)
- Xiang-Zhi Fang
- Department of Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ting Zhou
- Department of Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ji-Qian Xu
- Department of Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ya-Xin Wang
- Department of Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Miao-Miao Sun
- Department of Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ya-Jun He
- Department of Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Shang-Wen Pan
- Department of Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wei Xiong
- Department of Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhe-Kang Peng
- Department of Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xue-Hui Gao
- Department of Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - You Shang
- Department of Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China. .,Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
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18
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Humenick A, Chen BN, Wattchow DA, Zagorodnyuk VP, Dinning PG, Spencer NJ, Costa M, Brookes SJH. Characterization of putative interneurons in the myenteric plexus of human colon. Neurogastroenterol Motil 2021; 33:e13964. [PMID: 32839997 PMCID: PMC7772282 DOI: 10.1111/nmo.13964] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 07/07/2020] [Accepted: 07/20/2020] [Indexed: 12/13/2022]
Abstract
BACKGROUND The enteric nervous system contains multiple classes of neurons, distinguishable by morphology, immunohistochemical markers, and projections; however, specific combinations differ between species. Here, types of enteric neurons in human colon were characterized immunohistochemically, using retrograde tracing combined with multiple labeling immunohistochemistry, focussing on non-motor neurons. METHODS The fluorescent carbocyanine tracer, DiI, was applied to the myenteric plexus in ex vivo preparations, filling neurons projecting within the plexus. Limits of projection lengths of motor neurons were established, allowing them to be excluded from the analysis. Long ascending and descending interneurons were then distinguished by labeling for discriminating immunohistochemical markers: calbindin, calretinin, enkephalin, 5-hydroxytryptamine, nitric oxide synthase, and substance P. These results were combined with a previous published study in which nitric oxide synthase and choline acetyltransferase immunoreactivities were established. KEY RESULTS Long ascending neurons (with projections longer than 8 mm, which excludes more than 95% motor neurons) formed four types, in descending order of abundance, defined by immunoreactivity for: (a) ChAT+/ENK+, (b) ChAT+/ENK+/SP+, (c) ChAT+/Calb+, and (d) ChAT+/ENK+/Calb+. Long descending neurons, up to 70 mm long also formed at least four types, distinguished by immunoreactivity for (a) NOS + cells (without ChAT), (b) ChAT+/NOS+, (c) ChAT+/Calret+, and (d) ChAT+/5HT + cells (with or without NOS). CONCLUSIONS AND INFERENCES Long interneurons, which do not innervate muscularis externa, are likely to coordinate neural activity over distances of many centimeters along the colon. Characterizing their neurochemical coding provides a basis for understanding their roles, investigating their connectivity, and building a comprehensive account of human colonic enteric neurons.
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Affiliation(s)
- Adam Humenick
- Human Physiology, Medical Bioscience, College of Medicine and Public Health, Flinders University, South Australia 5042
| | - Bao Nan Chen
- Human Physiology, Medical Bioscience, College of Medicine and Public Health, Flinders University, South Australia 5042
| | - David A Wattchow
- Department of Surgery, Flinders Medical Centre, Human, South Australia 5042
| | | | - Phil G Dinning
- Department of Surgery, Flinders Medical Centre, Human, South Australia 5042
| | - Nick J Spencer
- Human Physiology, Medical Bioscience, College of Medicine and Public Health, Flinders University, South Australia 5042
| | - Marcello Costa
- Human Physiology, Medical Bioscience, College of Medicine and Public Health, Flinders University, South Australia 5042
| | - Simon JH Brookes
- Human Physiology, Medical Bioscience, College of Medicine and Public Health, Flinders University, South Australia 5042
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19
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Spencer NJ, Costa M, Hibberd TJ, Wood JD. Advances in colonic motor complexes in mice. Am J Physiol Gastrointest Liver Physiol 2021; 320:G12-G29. [PMID: 33085903 DOI: 10.1152/ajpgi.00317.2020] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The primary functions of the gastrointestinal (GI) tract are to absorb nutrients, water, and electrolytes that are essential for life. This is accompanied by the capability of the GI tract to mix ingested content to maximize absorption and effectively excrete waste material. There have been major advances in understanding intrinsic neural mechanisms involved in GI motility. This review highlights major advances over the past few decades in our understanding of colonic motor complexes (CMCs), the major intrinsic neural patterns that control GI motility. CMCs are generated by rhythmic coordinated firing of large populations of myenteric neurons. Initially, it was thought that serotonin release from the mucosa was required for CMC generation. However, careful experiments have now shown that neither the mucosa nor endogenous serotonin are required, although, evidence suggests enteroendocrine (EC) cells modulate CMCs. The frequency and extent of propagation of CMCs are highly dependent on mechanical stimuli (circumferential stretch). In summary, the isolated mouse colon emerges as a good model to investigate intrinsic mechanisms underlying colonic motility and provides an excellent preparation to explore potential therapeutic agents on colonic motility, in a highly controlled in vitro environment. In addition, during CMCs, the mouse colon facilitates investigations into the emergence of dynamic assemblies of extensive neural networks, applicable to the nervous system of different organisms.
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Affiliation(s)
- N J Spencer
- Visceral Neurophysiology Laboratory, College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Bedford Park, South Australia, Australia
| | - M Costa
- Visceral Neurophysiology Laboratory, College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Bedford Park, South Australia, Australia
| | - T J Hibberd
- Visceral Neurophysiology Laboratory, College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Bedford Park, South Australia, Australia
| | - J D Wood
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio
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20
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Furness JB, Di Natale M, Hunne B, Oparija-Rogenmozere L, Ward SM, Sasse KC, Powley TL, Stebbing MJ, Jaffey D, Fothergill LJ. The identification of neuronal control pathways supplying effector tissues in the stomach. Cell Tissue Res 2020; 382:433-445. [PMID: 33156383 DOI: 10.1007/s00441-020-03294-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Accepted: 09/11/2020] [Indexed: 12/14/2022]
Abstract
The stomach acts as a buffer between the ingestion of food and its processing in the small intestine. It signals to the brain to modulate food intake and it in turn regulates the passage of a nutrient-rich fluid, containing partly digested food, into the duodenum. These processes need to be finely controlled, for example to restrict reflux into the esophagus and to transfer digesta to the duodenum at an appropriate rate. Thus, the efferent pathways that control gastric volume, gastric peristalsis and digestive juice production are critically important. We review these pathways with an emphasis on the identities of the final motor neurons and comparisons between species. The major types of motor neurons arising from gastric enteric ganglia are as follows: immunohistochemically distinguishable excitatory and inhibitory muscle motor neurons; four neuron types innervating mucosal effectors (parietal cells, chief cells, gastrin cells and somatostatin cells); and vasodilator neurons. Sympathetic efferent neurons innervate intramural arteries, myenteric ganglia and gastric muscle. Vagal efferent neurons with cell bodies in the brain stem do not directly innervate gastric effector tissues; they are pre-enteric neurons that innervate each type of gastric enteric motor neuron. The principal transmitters and co-transmitters of gastric motor neurons, as well as key immunohistochemical markers, are the same in rat, pig, human and other species.
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Affiliation(s)
- John B Furness
- Department of Anatomy & Neuroscience, University of Melbourne, VIC, 3010, Parkville, Australia. .,Florey Institute of Neuroscience and Mental Health, VIC, 3010, Parkville, Australia.
| | - Madeleine Di Natale
- Department of Anatomy & Neuroscience, University of Melbourne, VIC, 3010, Parkville, Australia.,Florey Institute of Neuroscience and Mental Health, VIC, 3010, Parkville, Australia
| | - Billie Hunne
- Department of Anatomy & Neuroscience, University of Melbourne, VIC, 3010, Parkville, Australia
| | | | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, NV, Reno, USA
| | - Kent C Sasse
- Sasse Surgical Associates, and Renown Regional Medical Center, NV, Reno, USA
| | - Terry L Powley
- Department of Psychological Sciences, Purdue University, West Lafayette, IN, USA
| | - Martin J Stebbing
- Department of Anatomy & Neuroscience, University of Melbourne, VIC, 3010, Parkville, Australia.,Florey Institute of Neuroscience and Mental Health, VIC, 3010, Parkville, Australia
| | - Deborah Jaffey
- Department of Psychological Sciences, Purdue University, West Lafayette, IN, USA
| | - Linda J Fothergill
- Department of Anatomy & Neuroscience, University of Melbourne, VIC, 3010, Parkville, Australia.,Florey Institute of Neuroscience and Mental Health, VIC, 3010, Parkville, Australia
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21
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Fung C, Vanden Berghe P. Functional circuits and signal processing in the enteric nervous system. Cell Mol Life Sci 2020; 77:4505-4522. [PMID: 32424438 PMCID: PMC7599184 DOI: 10.1007/s00018-020-03543-6] [Citation(s) in RCA: 97] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 04/13/2020] [Accepted: 04/27/2020] [Indexed: 02/06/2023]
Abstract
The enteric nervous system (ENS) is an extensive network comprising millions of neurons and glial cells contained within the wall of the gastrointestinal tract. The major functions of the ENS that have been most studied include the regulation of local gut motility, secretion, and blood flow. Other areas that have been gaining increased attention include its interaction with the immune system, with the gut microbiota and its involvement in the gut-brain axis, and neuro-epithelial interactions. Thus, the enteric circuitry plays a central role in intestinal homeostasis, and this becomes particularly evident when there are faults in its wiring such as in neurodevelopmental or neurodegenerative disorders. In this review, we first focus on the current knowledge on the cellular composition of enteric circuits. We then further discuss how enteric circuits detect and process external information, how these signals may be modulated by physiological and pathophysiological factors, and finally, how outputs are generated for integrated gut function.
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Affiliation(s)
- Candice Fung
- Laboratory for Enteric NeuroScience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
| | - Pieter Vanden Berghe
- Laboratory for Enteric NeuroScience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium.
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22
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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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23
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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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24
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Smolilo DJ, Hibberd TJ, Costa M, Wattchow DA, De Fontgalland D, Spencer NJ. Intrinsic sensory neurons provide direct input to motor neurons and interneurons in mouse distal colon via varicose baskets. J Comp Neurol 2020; 528:2033-2043. [PMID: 32003462 DOI: 10.1002/cne.24872] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/22/2020] [Accepted: 01/26/2020] [Indexed: 12/20/2022]
Abstract
Connections from intrinsic primary afferent neurons (IPANs), to ascending motor and interneurons have been described in guinea pig colon. These mono- and polysynaptic circuits may underlie polarized motor reflexes evoked by local gut stimulation. There is a need to translate findings in guinea pig to mouse, a species increasingly used in enteric neuroscience. Here, mouse distal colon was immunolabeled for CGRP, a marker of putative IPANs. This revealed a combination of large, intensely immunofluorescent axons in myenteric plexus and circular muscle, and thinner varicose axons with less immunofluorescence. The latter formed dense, basket-like varicosity clusters (CGRP+ baskets) that enveloped myenteric nerve cell bodies. Immunolabeling after 4-5 days in organ culture caused loss of large CGRP+ axons, but not varicose CGRP+ fibers and CGRP+ baskets. Baskets were characterized further by triple labeling with CGRP, nitric oxide synthase (NOS) and calretinin (CALR) antibodies. Approximately half (48%) of nerve cell bodies inside CGRP+ baskets lacked both NOS and CALR, while two overlapping populations containing NOS and/or CALR comprised the remainder. Quantitative analysis revealed CGRP+ varicosities were most abundant in baskets, followed by CALR+ varicosities, with a high degree of colocalization between the two markers. Few NOS+ varicosities occurred in baskets. Significantly higher proportions of CALR+ and CGRP+ varicosities colocalized in baskets than in circular muscle. In conclusion, CGRP+ baskets in mouse colon are formed by intrinsic enteric neurons with a neurochemical profile consistent with IPANs and have direct connections to both excitatory and inhibitory neurons.
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Affiliation(s)
- David J Smolilo
- Visceral Neurophysiology Laboratory, College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Bedford Park, South Australia, Australia
| | - Timothy J Hibberd
- Visceral Neurophysiology Laboratory, College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Bedford Park, South Australia, Australia
| | - Marcello Costa
- Visceral Neurophysiology Laboratory, College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Bedford Park, South Australia, Australia
| | - David A Wattchow
- Visceral Neurophysiology Laboratory, College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Bedford Park, South Australia, Australia
| | - Dayan De Fontgalland
- Visceral Neurophysiology Laboratory, College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Bedford Park, South Australia, Australia
| | - Nick J Spencer
- Visceral Neurophysiology Laboratory, College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Bedford Park, South Australia, Australia
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Knauf C, Abot A, Wemelle E, Cani PD. Targeting the Enteric Nervous System to Treat Metabolic Disorders? "Enterosynes" as Therapeutic Gut Factors. Neuroendocrinology 2020; 110:139-146. [PMID: 31280267 DOI: 10.1159/000500602] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 04/28/2019] [Indexed: 11/19/2022]
Abstract
The gut-brain axis is of crucial importance for controlling glucose homeostasis. Alteration of this axis promotes the type 2 diabetes (T2D) phenotype (hyperglycaemia, insulin resistance). Recently, a new concept has emerged to demonstrate the crucial role of the enteric nervous system in the control of glycaemia via the hypothalamus. In diabetic patients and mice, modification of enteric neurons activity in the proximal part of the intestine generates a duodenal hyper-contractility that generates an aberrant message from the gut to the brain. In turn, the hypothalamus sends an aberrant efferent message that provokes a state of insulin resistance, which is characteristic of a T2D state. Targeting the enteric nervous system of the duodenum is now recognized as an innovative strategy for treatment of diabetes. By acting in the intestine, bioactive gut molecules that we called "enterosynes" can modulate the function of a specific type of neurons of the enteric nervous system to decrease the contraction of intestinal smooth muscle cells. Here, we focus on the origins of enterosynes (hormones, neurotransmitters, nutrients, microbiota, and immune factors), which could be considered therapeutic factors, and we describe their modes of action on enteric neurons. This unsuspected action of enterosynes is proposed for the treatment of T2D, but it could be applied for other therapeutic solutions that implicate communication between the gut and brain.
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Affiliation(s)
- Claude Knauf
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1220, Université Paul Sabatier, UPS, Institut de Recherche en Santé Digestive et Nutrition (IRSD), Toulouse, France,
- NeuroMicrobiota, European Associated Laboratory (EAL) INSERM, Toulouse, France,
| | - Anne Abot
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1220, Université Paul Sabatier, UPS, Institut de Recherche en Santé Digestive et Nutrition (IRSD), Toulouse, France
- NeuroMicrobiota, European Associated Laboratory (EAL) INSERM, Toulouse, France
| | - Eve Wemelle
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1220, Université Paul Sabatier, UPS, Institut de Recherche en Santé Digestive et Nutrition (IRSD), Toulouse, France
- NeuroMicrobiota, European Associated Laboratory (EAL) INSERM, Toulouse, France
| | - Patrice D Cani
- NeuroMicrobiota, European Associated Laboratory (EAL) INSERM, Toulouse, France
- UCLouvain, Université Catholique de Louvain, WELBIO - Walloon Excellence in Life Sciences and BIOtechnology, Louvain Drug Research Institute, Metabolism and Nutrition Research Group, Brussels, Belgium
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Costa M, Keightley LJ, Wiklendt L, Hibberd TJ, Arkwright JW, Omari T, Wattchow DA, Zagorodnyuk V, Brookes SJH, Dinning PG, Spencer NJ. Roles of three distinct neurogenic motor patterns during pellet propulsion in guinea‐pig distal colon. J Physiol 2019; 597:5125-5140. [DOI: 10.1113/jp278284] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Accepted: 08/15/2019] [Indexed: 12/29/2022] Open
Affiliation(s)
- Marcello Costa
- College of Medicine and Public Health & Centre for Neuroscience Flinders University, Discipline of Human Physiology Adelaide SA Australia
| | - Lauren J. Keightley
- College of Medicine and Public Health & Centre for Neuroscience Flinders University, Discipline of Human Physiology Adelaide SA Australia
| | - Lukasz Wiklendt
- College of Medicine and Public Health & Centre for Neuroscience Flinders University, Discipline of Human Physiology Adelaide SA Australia
| | - Timothy J. Hibberd
- College of Medicine and Public Health & Centre for Neuroscience Flinders University, Discipline of Human Physiology Adelaide SA Australia
| | - John W. Arkwright
- College of Science and Engineering Flinders University Adelaide SA Australia
| | - Taher Omari
- Discipline of Surgery and Gastroenterology Flinders Medical Centre Adelaide SA Australia
| | - David A. Wattchow
- College of Medicine and Public Health & Centre for Neuroscience Flinders University, Discipline of Human Physiology Adelaide SA Australia
- Discipline of Surgery and Gastroenterology Flinders Medical Centre Adelaide SA Australia
| | - Vladimir Zagorodnyuk
- College of Medicine and Public Health & Centre for Neuroscience Flinders University, Discipline of Human Physiology Adelaide SA Australia
| | - Simon J. H. Brookes
- College of Medicine and Public Health & Centre for Neuroscience Flinders University, Discipline of Human Physiology Adelaide SA Australia
| | - Phil G. Dinning
- College of Medicine and Public Health & Centre for Neuroscience Flinders University, Discipline of Human Physiology Adelaide SA Australia
- Discipline of Surgery and Gastroenterology Flinders Medical Centre Adelaide SA Australia
| | - Nick J. Spencer
- College of Medicine and Public Health & Centre for Neuroscience Flinders University, Discipline of Human Physiology Adelaide SA Australia
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Kuramoto H, Yoshimura R, Sakamoto H, Kadowaki M. Regional variations in the number distribution of intrinsic myenteric neurons and coinnervated motor endplates on the striated muscles in the rat esophagus. Auton Neurosci 2019; 219:25-32. [PMID: 31122598 DOI: 10.1016/j.autneu.2019.03.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 03/19/2019] [Accepted: 03/20/2019] [Indexed: 01/05/2023]
Abstract
The roles of intrinsic neurons and the significance of the coinnervated striated muscles in the esophagus are unclear. We examined the number distribution of intrinsic neurons and coinnervated motor endplates on the striated muscles in the rat esophagus using immunohistochemistry to investigate whether these neurons and coinnervated striated muscles may be relevant to the local control of esophageal motility. The number of PGP9.5-positive neurons was higher in the cervical esophagus (segment 1) and gradually decreased toward the aboral, with a moderate increase in the abdominal (segment 5). This pattern was similar to that of NOS-positive neurons, while the number of ChAT-positive neurons decreased toward the aboral, but it was not significantly different among segments 3 to 5. The number of ChAT-positive motor endplates increased toward the aboral, with the highest number in segment 5. The proportion of coinnervated motor endplates was approximately 80% in segments 1 to 4, but approximately 66% in segment 5. NPY-IR was localized in some nerve terminals among the smooth muscles of the muscularis mucosa and some NOS- or ChAT-positive esophageal intrinsic neurons. ENK-8-IR was found in some NOS- or ChAT-positive intrinsic neurons, and nerve terminals surrounding intrinsic neurons in the esophagus, but not in motor neurons at the NA or DMV. This study suggests that regional variations in the number of intrinsic neurons and coinnervated striated muscles in the rat esophagus may be involved in local regulations of esophageal motility, and that the rat esophageal intrinsic neurons may contain, at least, motor neurons and interneurons.
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Affiliation(s)
- Hirofumi Kuramoto
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan.
| | - Ryoichi Yoshimura
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan
| | - Hiroshi Sakamoto
- Department of Physical Therapy, Health Science University, Yamanashi, Japan
| | - Makoto Kadowaki
- Division of Gastrointestinal Pathophysiology, Institute of Natural Medicine, University of Toyama, Toyama, Japan
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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: 19] [Impact Index Per Article: 3.2] [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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Spencer NJ, Hibberd TJ, Travis L, Wiklendt L, Costa M, Hu H, Brookes SJ, Wattchow DA, Dinning PG, Keating DJ, Sorensen J. Identification of a Rhythmic Firing Pattern in the Enteric Nervous System That Generates Rhythmic Electrical Activity in Smooth Muscle. J Neurosci 2018; 38:5507-5522. [PMID: 29807910 PMCID: PMC8174132 DOI: 10.1523/jneurosci.3489-17.2018] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 04/30/2018] [Accepted: 05/09/2018] [Indexed: 11/21/2022] Open
Abstract
The enteric nervous system (ENS) contains millions of neurons essential for organization of motor behavior of the intestine. It is well established that the large intestine requires ENS activity to drive propulsive motor behaviors. However, the firing pattern of the ENS underlying propagating neurogenic contractions of the large intestine remains unknown. To identify this, we used high-resolution neuronal imaging with electrophysiology from neighboring smooth muscle. Myoelectric activity underlying propagating neurogenic contractions along murine large intestine [also referred to as colonic migrating motor complexes, (CMMCs)] consisted of prolonged bursts of rhythmic depolarizations at a frequency of ∼2 Hz. Temporal coordination of this activity in the smooth muscle over large spatial fields (∼7 mm, longitudinally) was dependent on the ENS. During quiescent periods between neurogenic contractions, recordings from large populations of enteric neurons, in mice of either sex, revealed ongoing activity. The onset of neurogenic contractions was characterized by the emergence of temporally synchronized activity across large populations of excitatory and inhibitory neurons. This neuronal firing pattern was rhythmic and temporally synchronized across large numbers of ganglia at ∼2 Hz. ENS activation preceded smooth muscle depolarization, indicating rhythmic depolarizations in smooth muscle were controlled by firing of enteric neurons. The cyclical emergence of temporally coordinated firing of large populations of enteric neurons represents a unique neural motor pattern outside the CNS. This is the first direct observation of rhythmic firing in the ENS underlying rhythmic electrical depolarizations in smooth muscle. The pattern of neuronal activity we identified underlies the generation of CMMCs.SIGNIFICANCE STATEMENT How the enteric nervous system (ENS) generates neurogenic contractions of smooth muscle in the gastrointestinal (GI) tract has been a long-standing mystery in vertebrates. It is well known that myogenic pacemaker cells exist in the GI tract [called interstitial cells of Cajal (ICCs)] that generate rhythmic myogenic contractions. However, the mechanisms underlying the generation of rhythmic neurogenic contractions of smooth muscle in the GI tract remains unknown. We developed a high-resolution neuronal imaging method with electrophysiology to address this issue. This technique revealed a novel pattern of rhythmic coordinated neuronal firing in the ENS that has never been identified. Rhythmic neuronal firing in the ENS was found to generate rhythmic neurogenic depolarizations in smooth muscle that underlie contraction of the GI tract.
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Affiliation(s)
- Nick J Spencer
- College of Medicine and Public Health and Centre for Neuroscience, Flinders University, Adelaide 5042, Australia,
| | - Timothy J Hibberd
- College of Medicine and Public Health and Centre for Neuroscience, Flinders University, Adelaide 5042, Australia
| | - Lee Travis
- College of Medicine and Public Health and Centre for Neuroscience, Flinders University, Adelaide 5042, Australia
| | - Lukasz Wiklendt
- College of Medicine and Public Health and Centre for Neuroscience, Flinders University, Adelaide 5042, Australia
| | - Marcello Costa
- College of Medicine and Public Health and Centre for Neuroscience, Flinders University, Adelaide 5042, Australia
| | - Hongzhen Hu
- Department of Anesthesiology, The Center for the Study of Itch, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Simon J Brookes
- College of Medicine and Public Health and Centre for Neuroscience, Flinders University, Adelaide 5042, Australia
| | - David A Wattchow
- Discipline of Surgery and Gastroenterology, Flinders Medical Centre, Bedford Park 5042, South Australia, Australia, and
| | - Phil G Dinning
- College of Medicine and Public Health and Centre for Neuroscience, Flinders University, Adelaide 5042, Australia
- Discipline of Surgery and Gastroenterology, Flinders Medical Centre, Bedford Park 5042, South Australia, Australia, and
| | - Damien J Keating
- College of Medicine and Public Health and Centre for Neuroscience, Flinders University, Adelaide 5042, Australia
| | - Julian Sorensen
- Cyber Sensing and Shaping, Cyber and Electronic Warfare Division, Defence, Science and Technology Group, Edinburgh, South Australia 5111, Australia
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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: 16] [Impact Index Per Article: 2.7] [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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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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Abot A, Cani PD, Knauf C. Impact of Intestinal Peptides on the Enteric Nervous System: Novel Approaches to Control Glucose Metabolism and Food Intake. Front Endocrinol (Lausanne) 2018; 9:328. [PMID: 29988396 PMCID: PMC6023997 DOI: 10.3389/fendo.2018.00328] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 05/31/2018] [Indexed: 12/13/2022] Open
Abstract
The gut is one of the most important sources of bioactive peptides in the body. In addition to their direct actions in the brain and/or peripheral tissues, the intestinal peptides can also have an impact on enteric nervous neurons. By modifying the endogenousproduction of these peptides, one may expect modify the "local" physiology such as glucose absorption, but also could have a "global" action via the gut-brain axis. Due to the various origins of gut peptides (i.e., nutrients, intestinal wall, gut microbiota) and the heterogeneity of enteric neurons population, the potential physiological parameters control by the interaction between the two partners are multiple. In this review, we will exclusively focus on the role of enteric nervous system as a potential target of gut peptides to control glucose metabolism and food intake. Potential therapeutic strategies based on per os administration of gut peptides to treat type 2 diabetes will be described.
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Affiliation(s)
- Anne Abot
- NeuroMicrobiota, European Associated Laboratory (EAL), INSERM, Université catholique de Louvain (UCL), Toulouse, France
- INSERM U1220 Institut de Recherche en Santé Digestive (IRSD), CHU Purpan, Université Toulouse III Paul Sabatier, Paris, France
| | - Patrice D. Cani
- NeuroMicrobiota, European Associated Laboratory (EAL), INSERM, Université catholique de Louvain (UCL), Toulouse, France
- Metabolism and Nutrition Research Group, Louvain Drug Research Institute (LDRI), WELBIO (Walloon Excellence in Life Sciences and BIOtechnology), Université catholique de Louvain (UCL), Brussels, Belgium
| | - Claude Knauf
- NeuroMicrobiota, European Associated Laboratory (EAL), INSERM, Université catholique de Louvain (UCL), Toulouse, France
- INSERM U1220 Institut de Recherche en Santé Digestive (IRSD), CHU Purpan, Université Toulouse III Paul Sabatier, Paris, France
- *Correspondence: Claude Knauf,
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Alcaino C, Farrugia G, Beyder A. Mechanosensitive Piezo Channels in the Gastrointestinal Tract. CURRENT TOPICS IN MEMBRANES 2017; 79:219-244. [PMID: 28728818 PMCID: PMC5606247 DOI: 10.1016/bs.ctm.2016.11.003] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Sensation of mechanical forces is critical for normal function of the gastrointestinal (GI) tract and abnormalities in mechanosensation are linked to GI pathologies. In the GI tract there are several mechanosensitive cell types-epithelial enterochromaffin cells, intrinsic and extrinsic enteric neurons, smooth muscle cells and interstitial cells of Cajal. These cells use mechanosensitive ion channels that respond to mechanical forces by altering transmembrane ionic currents in a process called mechanoelectrical coupling. Several mechanosensitive ionic conductances have been identified in the mechanosensory GI cells, ranging from mechanosensitive voltage-gated sodium and calcium channels to the mechanogated ion channels, such as the two-pore domain potassium channels K2P (TREK-1) and nonselective cation channels from the transient receptor potential family. The recently discovered Piezo channels are increasingly recognized as significant contributors to cellular mechanosensitivity. Piezo1 and Piezo2 are nonselective cationic ion channels that are directly activated by mechanical forces and have well-defined biophysical and pharmacologic properties. The role of Piezo channels in the GI epithelium is currently under investigation and their role in the smooth muscle syncytium and enteric neurons is still not known. In this review, we outline the current state of knowledge on mechanosensitive ion channels in the GI tract, with a focus on the known and potential functions of the Piezo channels.
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Affiliation(s)
- C Alcaino
- Mayo Clinic College of Medicine, Rochester, MN, United States
| | - G Farrugia
- Mayo Clinic College of Medicine, Rochester, MN, United States
| | - A Beyder
- Mayo Clinic College of Medicine, Rochester, MN, United States
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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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Palmer G, Hibberd TJ, Roose T, Brookes SJH, Taylor M. Measurement of strains experienced by viscerofugal nerve cell bodies during mechanosensitive firing using digital image correlation. Am J Physiol Gastrointest Liver Physiol 2016; 311:G869-G879. [PMID: 27514482 DOI: 10.1152/ajpgi.00397.2015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 08/02/2016] [Indexed: 01/31/2023]
Abstract
Mechanosensory neurons detect physical events in the local environments of the tissues that they innervate. Studies of mechanosensitivity of neurons or nerve endings in the gut have related their firing to strain, wall tension, or pressure. Digital image correlation (DIC) is a technique from materials engineering that can be adapted to measure the local physical environments of afferent neurons at high resolution. Flat-sheet preparations of guinea pig distal colon were set up with arrays of tissue markers in vitro. Firing of single viscerofugal neurons was identified in extracellular colonic nerve recordings. The locations of viscerofugal nerve cell bodies were inferred by mapping firing responses to focal application of the nicotinic receptor agonist 1,1-dimethyl-4-phenylpiperazinium iodide. Mechanosensory firing was recorded during load-evoked uniaxial or biaxial distensions. Distension caused movement of surface markers which was captured by video imaging. DIC tracked the markers, interpolating the mechanical state of the gut at the location of the viscerofugal nerve cell body. This technique revealed heterogeneous load-evoked strain within preparations. Local strains at viscerofugal nerve cell bodies were usually smaller than global strain measurements and correlated more closely with mechanosensitive firing. Both circumferential and longitudinal strain activated viscerofugal neurons. Simultaneous loading in circumferential and longitudinal axes caused the highest levels of viscerofugal neuron firing. Multiaxial strains, reflecting tissue shearing and changing area, linearly correlated with mechanosensory firing of viscerofugal neurons. Viscerofugal neurons were mechanically sensitive to both local circumferential and local longitudinal gut strain, and appear to lack directionality in their stretch sensitivity.
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Affiliation(s)
- Gwen Palmer
- Bioengineering Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton, United Kingdom
| | - Timothy J Hibberd
- Department of Human Physiology and Centre for Neuroscience, Flinders University, Adelaide, Australia; and
| | - Tiina Roose
- Bioengineering Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton, United Kingdom
| | - Simon J H Brookes
- Department of Human Physiology and Centre for Neuroscience, Flinders University, Adelaide, Australia; and
| | - Mark Taylor
- School of Computer Science, Engineering and Mathematics, Flinders University, Adelaide, Australia
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Enteric nervous system assembly: Functional integration within the developing gut. Dev Biol 2016; 417:168-81. [PMID: 27235816 DOI: 10.1016/j.ydbio.2016.05.030] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 04/26/2016] [Accepted: 05/24/2016] [Indexed: 02/08/2023]
Abstract
Co-ordinated gastrointestinal function is the result of integrated communication between the enteric nervous system (ENS) and "effector" cells in the gastrointestinal tract. Unlike smooth muscle cells, interstitial cells, and the vast majority of cell types residing in the mucosa, enteric neurons and glia are not generated within the gut. Instead, they arise from neural crest cells that migrate into and colonise the developing gastrointestinal tract. Although they are "later" arrivals into the developing gut, enteric neural crest-derived cells (ENCCs) respond to many of the same secreted signalling molecules as the "resident" epithelial and mesenchymal cells, and several factors that control the development of smooth muscle cells, interstitial cells and epithelial cells also regulate ENCCs. Much progress has been made towards understanding the migration of ENCCs along the gastrointestinal tract and their differentiation into neurons and glia. However, our understanding of how enteric neurons begin to communicate with each other and extend their neurites out of the developing plexus layers to innervate the various cell types lining the concentric layers of the gastrointestinal tract is only beginning. It is critical for postpartum survival that the gastrointestinal tract and its enteric circuitry are sufficiently mature to cope with the influx of nutrients and their absorption that occurs shortly after birth. Subsequently, colonisation of the gut by immune cells and microbiota during postnatal development has an important impact that determines the ultimate outline of the intrinsic neural networks of the gut. In this review, we describe the integrated development of the ENS and its target cells.
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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: 89] [Impact Index Per Article: 9.9] [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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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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Mazzuoli-Weber G, Schemann M. Mechanosensitivity in the enteric nervous system. Front Cell Neurosci 2015; 9:408. [PMID: 26528136 PMCID: PMC4602087 DOI: 10.3389/fncel.2015.00408] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 09/25/2015] [Indexed: 01/20/2023] Open
Abstract
The enteric nervous system (ENS) autonomously controls gut muscle activity. Mechanosensitive enteric neurons (MEN) initiate reflex activity by responding to mechanical deformation of the gastrointestinal wall. MEN throughout the gut primarily respond to compression or stretch rather than to shear force. Some MEN are multimodal as they respond to compression and stretch. Depending on the region up to 60% of the entire ENS population responds to mechanical stress. MEN fire action potentials after mechanical stimulation of processes or soma although they are more sensitive to process deformation. There are at least two populations of MEN based on their sensitivity to different modalities of mechanical stress and on their firing pattern. (1) Rapidly, slowly and ultra-slowly adapting neurons which encode compressive forces. (2) Ultra-slowly adapting stretch-sensitive neurons encoding tensile forces. Rapid adaptation of firing is typically observed after compressive force while slow adaptation or ongoing spike discharge occurs often during tensile stress (stretch). All MEN have some common properties: they receive synaptic input, are low fidelity mechanoreceptors and are multifunctional in that some serve interneuronal others even motor functions. Consequently, MEN possess processes with mechanosensitive as well as efferent functions. This raises the intriguing hypothesis that MEN sense and control muscle activity at the same time as servo-feedback loop. The mechanosensitive channel(s) or receptor(s) expressed by the different MEN populations are unknown. Future concepts have to incorporate compressive and tensile-sensitive MEN into neural circuits that controls muscle activity. They may interact to control various forms of a particular motor pattern or regulate different motor patterns independently from each other.
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Affiliation(s)
| | - Michael Schemann
- Human Biology, Technische Universitaet Muenchen Freising, Germany
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40
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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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41
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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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42
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Dong H, Jiang Y, Dong J, Mittal RK. Inhibitory motor neurons of the esophageal myenteric plexus are mechanosensitive. Am J Physiol Cell Physiol 2014; 308:C405-13. [PMID: 25540174 DOI: 10.1152/ajpcell.00159.2014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Mechanosensitivity of enteric neurons has been reported in the small intestine and colon, but not in the esophagus. Our earlier in vivo studies show that mechanical stretch of the esophagus in the axial direction induces neurally mediated relaxation of the lower esophageal sphincter, possibly through mechanosensitive motor neurons. However, this novel notion that the motor neurons are mechanosensitive has not been examined in isolated esophageal myenteric motor neurons. The goal of our present study was to examine the mechanosensitivity of esophageal motor neurons in primary culture and elucidate the underlying molecular mechanisms. Immmunocytochemical analysis revealed that >95% cells were positive for the neuronal marker protein gene product 9.5 and that 66% of these cells costained with protein gene product 9.5 and neuronal nitric oxide (NO) synthase. Hypotonic solution induced an increase in the cytoplasm volume in all cells that was independent of extracellular Ca(2+). Hypotonic solution and mechanical stretch induced cytoplasmic free Ca(2+) signaling in ~65% of neurons in the presence, but not absence, of extracellular Ca(2+). Neurons grown on the elastic membrane responded to mechanical stretch by an increase in neuronal size and Ca(2+) signaling simultaneously. Hypotonic stretch-induced cytoplasmic free Ca(2+) signaling was not affected by extracellular Mg(2+), 5-nitro-2-(3-phenylpropylamino)benzoic acid, and nifedipine but was attenuated by 2-aminoethoxydiphenyl borate, Gd(3+), and Grammostola mechanotoxin 4, blockers of the stretch-activated ion channels. In ~57% of the neurons, hypotonic stretch also induced Ca(2+)-dependent cytoplasmic NO production, which was abolished by Grammostola mechanotoxin 4. These results prove that the esophageal inhibitory motor neurons possess a mechanosensitive property and also provide novel insights into the stretch-activated ion channel-Ca(2+)-NO signaling pathway in these neurons.
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Affiliation(s)
- Hui Dong
- Division of Gastroenterology, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California; and Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Yanfen Jiang
- Division of Gastroenterology, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California; and Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Jane Dong
- Division of Gastroenterology, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California; and Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Ravinder K Mittal
- Division of Gastroenterology, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California; and Veterans Affairs San Diego Healthcare System, San Diego, California
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43
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The enteric nervous system and gastrointestinal innervation: integrated local and central control. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 817:39-71. [PMID: 24997029 DOI: 10.1007/978-1-4939-0897-4_3] [Citation(s) in RCA: 480] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The digestive system is innervated through its connections with the central nervous system (CNS) and by the enteric nervous system (ENS) within the wall of the gastrointestinal tract. The ENS works in concert with CNS reflex and command centers and with neural pathways that pass through sympathetic ganglia to control digestive function. There is bidirectional information flow between the ENS and CNS and between the ENS and sympathetic prevertebral ganglia.The ENS in human contains 200-600 million neurons, distributed in many thousands of small ganglia, the great majority of which are found in two plexuses, the myenteric and submucosal plexuses. The myenteric plexus forms a continuous network that extends from the upper esophagus to the internal anal sphincter. Submucosal ganglia and connecting fiber bundles form plexuses in the small and large intestines, but not in the stomach and esophagus. The connections between the ENS and CNS are carried by the vagus and pelvic nerves and sympathetic pathways. Neurons also project from the ENS to prevertebral ganglia, the gallbladder, pancreas and trachea.The relative roles of the ENS and CNS differ considerably along the digestive tract. Movements of the striated muscle esophagus are determined by neural pattern generators in the CNS. Likewise the CNS has a major role in monitoring the state of the stomach and, in turn, controlling its contractile activity and acid secretion, through vago-vagal reflexes. In contrast, the ENS in the small intestine and colon contains full reflex circuits, including sensory neurons, interneurons and several classes of motor neuron, through which muscle activity, transmucosal fluid fluxes, local blood flow and other functions are controlled. The CNS has control of defecation, via the defecation centers in the lumbosacral spinal cord. The importance of the ENS is emphasized by the life-threatening effects of some ENS neuropathies. By contrast, removal of vagal or sympathetic connections with the gastrointestinal tract has minor effects on GI function. Voluntary control of defecation is exerted through pelvic connections, but cutting these connections is not life-threatening and other functions are little affected.
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Chambers JD, Thomas EA, Bornstein JC. Mathematical modelling of enteric neural motor patterns. Clin Exp Pharmacol Physiol 2014; 41:155-64. [PMID: 24471867 DOI: 10.1111/1440-1681.12209] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 11/21/2013] [Accepted: 11/26/2013] [Indexed: 01/07/2023]
Abstract
1. The enteric nervous system modulates intestinal behaviours, such as motor patterns and secretion. Although much is known about different types of neurons and simple reflexes in the intestine, it remains unclear how complex behaviours are generated. 2. Mathematical modelling is an important tool for assisting the understanding of how the neurons and reflexes can be pieced together to generate intestinal behaviours. 3. Models have identified a functional role for slow excitatory post-synaptic potentials (EPSPs) by distinguishing between fast and slow EPSPs in the ascending excitation reflex. These models also discovered coordinated firing of similarly located neurons as emergent properties of feed-forward networks of interneurons in the intestine. A model of the recurrent network of intrinsic sensory neurons identified important control mechanisms to prevent uncontrolled firing due to positive feedback and that the interaction between these control mechanisms and slow EPSPs is necessary for the networks to encode ongoing sensory stimuli. This model also showed that such networks may mediate migrating motor complexes. 4. A network model of vasoactive intestinal peptide neurons in the submucosal plexus found this relatively sparse recurrent network could produce uncontrolled firing under conditions that appear to be related to cholera toxin-induced hypersecretion. 5. Abstract modelling of the intestinal fed-state motor patterns has identified how stationary contractions can arise from a polarized network. 6. These models have also helped predict and/or explained pharmacological evidence for two rhythm generators and the requirement of feedback from contractions in the circular muscle.
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Affiliation(s)
- Jordan D Chambers
- Department of Physiology, University of Melbourne, Victoria, Australia
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45
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Mazet B. Gastrointestinal motility and its enteric actors in mechanosensitivity: past and present. Pflugers Arch 2014; 467:191-200. [PMID: 25366494 DOI: 10.1007/s00424-014-1635-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 10/14/2014] [Accepted: 10/19/2014] [Indexed: 12/14/2022]
Abstract
Coordinated contractions of the smooth muscle layers of the gastrointestinal (GI) tract are required to produce motor patterns that ensure normal GI motility. The crucial role of the enteric nervous system (ENS), the intrinsic ganglionated network located within the GI wall, has long been recognized in the generation of the main motor patterns. However, devising an appropriate motility requires the integration of informations emanating from the lumen of the GI tract. As already found more than half a century ago, the ability of the GI tract to respond to mechanical forces such as stretch is not restricted to neuronal mechanisms. Instead, mechanosensitivity is now recognized as a property of several non-neuronal cell types, the excitability of which is probably involved in shaping the motor patterns. This brief review gives an overview on how mechanosensitivity of different cell types in the GI tract has been established and, whenever available, on what ionic conductances are involved in mechanotransduction and their potential impact on normal GI motility.
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Affiliation(s)
- Bruno Mazet
- Aix Marseille Université, CNRS, CRN2M UMR 7286, CS80011 Bd Pierre Dramard, 13344, Marseille Cedex 15, France,
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The effect of bradykinin on the electrical activity of rat myenteric neurons. Eur J Pharmacol 2014; 738:158-69. [PMID: 24886885 DOI: 10.1016/j.ejphar.2014.05.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 04/01/2014] [Accepted: 05/10/2014] [Indexed: 01/21/2023]
Abstract
Bradykinin is a mediator involved in inflammatory processes in the gut. Here we investigated the effect of bradykinin on the electrical activity of rat myenteric neurons, the key players for regulation of gastrointestinal motility. Bradykinin (2 × 10(-8)mol/l) induced a biphasic increase in frequency of action potentials measured with microelectrode arrays. This increase was mirrored by a biphasic increase in cytosolic Ca(2+) concentration ([Ca(2+)]i), which was observed in about 40% of the myenteric neurons. The bradykinin B1 receptor agonist des-arg(9)-bradykinin as well as the bradykinin B2 receptor agonist hyp(3)-bradykinin induced a similar effect on [Ca(2+)]i. Immunocytochemical stainings confirmed the expression of both receptor types by myenteric ganglionic cells. Real time PCR showed that the inducible B1 receptor was upregulated during cell culture. The inhibition of cyclooxygenases with piroxicam reduced the effect of bradykinin on the electrical activity of myenteric neurons. The suppression of the glial growth on microelectrode arrays did not affect the bradykinin-induced change in frequency of action potentials. This suggests that prostaglandins, which probably mediate the effect of bradykinin, are not exclusively released from glial cells. The bradykinin-induced increase in [Ca(2+)]i was dependent on the presence of extracellular Ca(2+) and was inhibited by Co(2+), Cd(2+), and Ni(2+), blockers of voltage-dependent Ca(2+) channels, indicating a stimulation of the influx of extracellular Ca(2+) by the kinin. Consequently, bradykinin induces a Ca(2+) influx in myenteric neurons via Ca(2+) channels in the plasma membrane.
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Foong JPP, Tough IR, Cox HM, Bornstein JC. Properties of cholinergic and non-cholinergic submucosal neurons along the mouse colon. J Physiol 2013; 592:777-93. [PMID: 24344165 DOI: 10.1113/jphysiol.2013.265686] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Submucosal neurons are vital regulators of water and electrolyte secretion and local blood flow in the gut. Due to the availability of transgenic models for enteric neuropathies, the mouse has emerged as the research model of choice, but much is still unknown about the murine submucosal plexus. The progeny of choline acetyltransferase (ChAT)-Cre × ROSA26(YFP) reporter mice, ChAT-Cre;R26R-yellow fluorescent protein (YFP) mice, express YFP in every neuron that has ever expressed ChAT. With the aid of the robust YFP staining in these mice, we correlated the neurochemistry, morphology and electrophysiology of submucosal neurons in distal colon. We also examined whether there are differences in neurochemistry along the colon and in neurally mediated vectorial ion transport between the proximal and distal colon. All YFP(+) submucosal neurons also contained ChAT. Two main neurochemical but not electrophysiological groups of neurons were identified: cholinergic (containing ChAT) or non-cholinergic. The vast majority of neurons in the middle and distal colon were non-cholinergic but contained vasoactive intestinal peptide. In the distal colon, non-cholinergic neurons had one or two axons, whereas the cholinergic neurons examined had only one axon. All submucosal neurons exhibited S-type electrophysiology, shown by the lack of long after-hyperpolarizing potentials following their action potentials and fast excitatory postsynaptic potentials (EPSPs). Fast EPSPs were predominantly nicotinic, and somatic action potentials were mediated by tetrodotoxin-resistant voltage-gated channels. The size of submucosal ganglia decreased but the proportion of cholinergic neurons increased distally along the colon. The distal colon had a significantly larger nicotinic ion transport response than the proximal colon. This work shows that the properties of murine submucosal neurons and their control of epithelial ion transport differ between colonic regions. There are several key differences between the murine submucous plexus and that of other animals, including a lack of conventional intrinsic sensory neurons, which suggests there is an incomplete neuronal circuitry within the murine submucous plexus.
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Affiliation(s)
- Jaime Pei Pei Foong
- Department of Physiology, University of Melbourne, Parkville, Vic. 3010, Australia.
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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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Costa M, Wiklendt L, Arkwright JW, Spencer NJ, Omari T, Brookes SJH, Dinning PG. An experimental method to identify neurogenic and myogenic active mechanical states of intestinal motility. Front Syst Neurosci 2013; 7:7. [PMID: 23596400 PMCID: PMC3622892 DOI: 10.3389/fnsys.2013.00007] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 03/25/2013] [Indexed: 01/28/2023] Open
Abstract
Excitatory and inhibitory enteric neural input to intestinal muscle acting on ongoing myogenic activity determines the rich repertoire of motor patterns involved in digestive function. The enteric neural activity cannot yet be established during movement of intact intestine in vivo or in vitro. We propose the hypothesis that is possible to deduce indirectly, but reliably, the state of activation of the enteric neural input to the muscle from measurements of the mechanical state of the intestinal muscle. The fundamental biomechanical model on which our hypothesis is based is the “three-element model” proposed by Hill. Our strategy is based on simultaneous video recording of changes in diameters and intraluminal pressure with a fiber-optic manometry in isolated segments of rabbit colon. We created a composite spatiotemporal map (DPMap) from diameter (DMap) and pressure changes (PMaps). In this composite map rhythmic myogenic motor patterns can readily be distinguished from the distension induced neural peristaltic contractions. Plotting the diameter changes against corresponding pressure changes at each location of the segment, generates “orbits” that represent the state of the muscle according to its ability to contract or relax actively or undergoing passive changes. With a software developed in MatLab, we identified twelve possible discrete mechanical states and plotted them showing where the intestine actively contracted and relaxed isometrically, auxotonically or isotonically, as well as where passive changes occurred or was quiescent. Clustering all discrete active contractions and relaxations states generated for the first time a spatio-temporal map of where enteric excitatory and inhibitory neural input to the muscle occurs during physiological movements. Recording internal diameter by an impedance probe proved equivalent to measuring external diameter, making possible to further develop similar strategy in vivo and humans.
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Affiliation(s)
- Marcello Costa
- Department of Human Physiology, School of Medicine, Flinders University Bedford Park, SA, South Australia
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Latorre R, Levi R, Varona P. Transformation of context-dependent sensory dynamics into motor behavior. PLoS Comput Biol 2013; 9:e1002908. [PMID: 23459114 PMCID: PMC3572992 DOI: 10.1371/journal.pcbi.1002908] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 12/19/2012] [Indexed: 11/24/2022] Open
Abstract
The intrinsic dynamics of sensory networks play an important role in the sensory-motor transformation. In this paper we use conductance based models and electrophysiological recordings to address the study of the dual role of a sensory network to organize two behavioral context-dependent motor programs in the mollusk Clione limacina. We show that: (i) a winner take-all dynamics in the gravimetric sensory network model drives the typical repetitive rhythm in the wing central pattern generator (CPG) during routine swimming; (ii) the winnerless competition dynamics of the same sensory network organizes the irregular pattern observed in the wing CPG during hunting behavior. Our model also shows that although the timing of the activity is irregular, the sequence of the switching among the sensory cells is preserved whenever the same set of neurons are activated in a given time window. These activation phase locks in the sensory signals are transformed into specific events in the motor activity. The activation phase locks can play an important role in motor coordination driven by the intrinsic dynamics of a multifunctional sensory organ. How sensory information is transformed into effective motor action is one of the most fundamental questions in neuroscience. As this question is difficult to assess experimentally, biophysical models of sensory, central and motor systems contribute to understand the information processing mechanisms involved in this transformation. Biophysical models can be informed by electrophysiological data in those situations where it is possible to record neural activity at all stages of sensory-motor processing. In this paper we use this approach to describe the dual dynamics of a multifunctional sensory organ in the mollusk Clione limacina and its transformation into two different motor programs. Our experimental and modeling results indicate that the sensory signals are modified to fit the changing behavioral context, and they are readily interpreted by the rest of the nervous system to produce the correct motor output.
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Affiliation(s)
- Roberto Latorre
- Grupo de Neurocomputación Biológica, Dpto. de Ingeniería Informática, Escuela Politécnica Superior, Universidad Autónoma de Madrid, Madrid, Spain.
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