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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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2
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Krishnan S, Klingauf J. The readily retrievable pool of synaptic vesicles. Biol Chem 2023; 404:385-397. [PMID: 36867726 DOI: 10.1515/hsz-2022-0298] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 02/16/2023] [Indexed: 03/05/2023]
Abstract
In the CNS communication between neurons occurs at synapses by secretion of neurotransmitter via exocytosis of synaptic vesicles (SVs) at the active zone. Given the limited number of SVs in presynaptic boutons a fast and efficient recycling of exocytosed membrane and proteins by triggered compensatory endocytosis is required to maintain neurotransmission. Thus, pre-synapses feature a unique tight coupling of exo- and endocytosis in time and space resulting in the reformation of SVs with uniform morphology and well-defined molecular composition. This rapid response requires early stages of endocytosis at the peri-active zone to be well choreographed to ensure reformation of SVs with high fidelity. The pre-synapse can address this challenge by a specialized membrane microcompartment, where a pre-sorted and pre-assembled readily retrievable pool (RRetP) of endocytic membrane patches is formed, consisting of the vesicle cargo, presumably bound within a nucleated Clathrin and adaptor complex. This review considers evidence for the RRetP microcompartment to be the primary organizer of presynaptic triggered compensatory endocytosis.
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Affiliation(s)
- Sai Krishnan
- Institute of Medical Physics and Biophysics, University of Münster, Robert-Koch Strasse 31, D-48149, Münster, Germany
| | - Jürgen Klingauf
- Institute of Medical Physics and Biophysics, University of Münster, Robert-Koch Strasse 31, D-48149, Münster, Germany.,Center for Soft Nanoscience, Busso-Peus Strasse 10, D-48149, Münster, Germany
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3
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Caillaud M, Le Dréan ME, De-Guilhem-de-Lataillade A, Le Berre-Scoul C, Montnach J, Nedellec S, Loussouarn G, Paillé V, Neunlist M, Boudin H. A functional network of highly pure enteric neurons in a dish. Front Neurosci 2023; 16:1062253. [PMID: 36685225 PMCID: PMC9853279 DOI: 10.3389/fnins.2022.1062253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 12/02/2022] [Indexed: 01/09/2023] Open
Abstract
The enteric nervous system (ENS) is the intrinsic nervous system that innervates the entire digestive tract and regulates major digestive functions. Recent evidence has shown that functions of the ENS critically rely on enteric neuronal connectivity; however, experimental models to decipher the underlying mechanisms are limited. Compared to the central nervous system, for which pure neuronal cultures have been developed for decades and are recognized as a reference in the field of neuroscience, an equivalent model for enteric neurons is lacking. In this study, we developed a novel model of highly pure rat embryonic enteric neurons with dense and functional synaptic networks. The methodology is simple and relatively fast. We characterized enteric neurons using immunohistochemical, morphological, and electrophysiological approaches. In particular, we demonstrated the applicability of this culture model to multi-electrode array technology as a new approach for monitoring enteric neuronal network activity. This in vitro model of highly pure enteric neurons represents a valuable new tool for better understanding the mechanisms involved in the establishment and maintenance of enteric neuron synaptic connectivity and functional networks.
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Affiliation(s)
- Martial Caillaud
- Nantes Université, INSERM, TENS, The Enteric Nervous System in Gut and Brain Diseases, IMAD, Nantes, France,*Correspondence: Martial Caillaud,
| | - Morgane E. Le Dréan
- Nantes Université, INSERM, TENS, The Enteric Nervous System in Gut and Brain Diseases, IMAD, Nantes, France
| | | | - Catherine Le Berre-Scoul
- Nantes Université, INSERM, TENS, The Enteric Nervous System in Gut and Brain Diseases, IMAD, Nantes, France
| | - Jérôme Montnach
- Nantes Université, CNRS, INSERM, L’institut du Thorax, Nantes, France
| | - Steven Nedellec
- Nantes Université, CHU Nantes, CNRS, INSERM, BioCore, US16, SFR Bonamy, Nantes, France
| | - Gildas Loussouarn
- Nantes Université, CNRS, INSERM, L’institut du Thorax, Nantes, France
| | - Vincent Paillé
- Nantes Université, INRAE, IMAD, CRNH-O, UMR 1280, PhAN, Nantes, France
| | - Michel Neunlist
- Nantes Université, INSERM, TENS, The Enteric Nervous System in Gut and Brain Diseases, IMAD, Nantes, France
| | - Hélène Boudin
- Nantes Université, INSERM, TENS, The Enteric Nervous System in Gut and Brain Diseases, IMAD, Nantes, France
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4
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Enteric neuroimmune interactions coordinate intestinal responses in health and disease. Mucosal Immunol 2022; 15:27-39. [PMID: 34471248 PMCID: PMC8732275 DOI: 10.1038/s41385-021-00443-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 08/02/2021] [Accepted: 08/05/2021] [Indexed: 02/04/2023]
Abstract
The enteric nervous system (ENS) of the gastrointestinal (GI) tract interacts with the local immune system bidirectionally. Recent publications have demonstrated that such interactions can maintain normal GI functions during homeostasis and contribute to pathological symptoms during infection and inflammation. Infection can also induce long-term changes of the ENS resulting in the development of post-infectious GI disturbances. In this review, we discuss how the ENS can regulate and be regulated by immune responses and how such interactions control whole tissue physiology. We also address the requirements for the proper regeneration of the ENS and restoration of GI function following the resolution of infection.
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Boesmans W, Hao MM, Fung C, Li Z, Van den Haute C, Tack J, Pachnis V, Vanden Berghe P. Structurally defined signaling in neuro-glia units in the enteric nervous system. Glia 2019; 67:1167-1178. [PMID: 30730592 PMCID: PMC6593736 DOI: 10.1002/glia.23596] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 01/11/2019] [Accepted: 01/11/2019] [Indexed: 12/21/2022]
Abstract
Coordination of gastrointestinal function relies on joint efforts of enteric neurons and glia, whose crosstalk is vital for the integration of their activity. To investigate the signaling mechanisms and to delineate the spatial aspects of enteric neuron-to-glia communication within enteric ganglia we developed a method to stimulate single enteric neurons while monitoring the activity of neighboring enteric glial cells. We combined cytosolic calcium uncaging of individual enteric neurons with calcium imaging of enteric glial cells expressing a genetically encoded calcium indicator and demonstrate that enteric neurons signal to enteric glial cells through pannexins using paracrine purinergic pathways. Sparse labeling of enteric neurons and high-resolution analysis of the structural relation between neuronal cell bodies, varicose release sites and enteric glia uncovered that this form of neuron-to-glia communication is contained between the cell body of an enteric neuron and its surrounding enteric glial cells. Our results reveal the spatial and functional foundation of neuro-glia units as an operational cellular assembly in the enteric nervous system.
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Affiliation(s)
- Werend Boesmans
- Laboratory for Enteric NeuroScience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium.,Department of Pathology, GROW-School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands.,Biomedical Research Institute (BIOMED), Hasselt University, Hasselt, Belgium
| | - Marlene M Hao
- Laboratory for Enteric NeuroScience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium.,Department of Anatomy and Neuroscience, University of Melbourne, Melbourne, Australia
| | - Candice Fung
- Laboratory for Enteric NeuroScience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
| | - Zhiling Li
- Laboratory for Enteric NeuroScience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
| | - Chris Van den Haute
- Laboratory for Neurobiology and Gene Therapy, Department of Neurosciences, University of Leuven, Leuven, Belgium.,Leuven Viral Vector Core, University of Leuven, Leuven, Belgium
| | - Jan Tack
- Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
| | - Vassilis Pachnis
- Development and Homeostasis of the Nervous System Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Pieter Vanden Berghe
- Laboratory for Enteric NeuroScience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
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6
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Boesmans W, Hao MM, Vanden Berghe P. Optogenetic and chemogenetic techniques for neurogastroenterology. Nat Rev Gastroenterol Hepatol 2018; 15:21-38. [PMID: 29184183 DOI: 10.1038/nrgastro.2017.151] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Optogenetics and chemogenetics comprise a wide variety of applications in which genetically encoded actuators and indicators are used to modulate and monitor activity with high cellular specificity. Over the past 10 years, development of these genetically encoded tools has contributed tremendously to our understanding of integrated physiology. In concert with the continued refinement of probes, strategies to target transgene expression to specific cell types have also made much progress in the past 20 years. In addition, the successful implementation of optogenetic and chemogenetic techniques thrives thanks to ongoing advances in live imaging microscopy and optical technology. Although innovation of optogenetic and chemogenetic methods has been primarily driven by researchers studying the central nervous system, these techniques also hold great promise to boost research in neurogastroenterology. In this Review, we describe the different classes of tools that are currently available and give an overview of the strategies to target them to specific cell types in the gut wall. We discuss the possibilities and limitations of optogenetic and chemogenetic technology in the gut and provide an overview of their current use, with a focus on the enteric nervous system. Furthermore, we suggest some experiments that can advance our understanding of how the intrinsic and extrinsic neural networks of the gut control gastrointestinal function.
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Affiliation(s)
- Werend Boesmans
- Laboratory for Enteric Neuroscience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Herestraat 49, O&N 1 Box 701, 3000 Leuven, Belgium.,Department of Pathology, Maastricht University Medical Center, P. Debeijelaan 25, 6229 HX, Maastricht, The Netherlands
| | - Marlene M Hao
- Laboratory for Enteric Neuroscience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Herestraat 49, O&N 1 Box 701, 3000 Leuven, Belgium.,Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Pieter Vanden Berghe
- Laboratory for Enteric Neuroscience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Herestraat 49, O&N 1 Box 701, 3000 Leuven, Belgium
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7
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Fung C, Boesmans W, Cirillo C, Foong JPP, Bornstein JC, Vanden Berghe P. VPAC Receptor Subtypes Tune Purinergic Neuron-to-Glia Communication in the Murine Submucosal Plexus. Front Cell Neurosci 2017; 11:118. [PMID: 28487635 PMCID: PMC5403822 DOI: 10.3389/fncel.2017.00118] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 04/10/2017] [Indexed: 12/20/2022] Open
Abstract
The enteric nervous system (ENS) situated within the gastrointestinal tract comprises an intricate network of neurons and glia which together regulate intestinal function. The exact neuro-glial circuitry and the signaling molecules involved are yet to be fully elucidated. Vasoactive intestinal peptide (VIP) is one of the main neurotransmitters in the gut, and is important for regulating intestinal secretion and motility. However, the role of VIP and its VPAC receptors within the enteric circuitry is not well understood. We investigated this in the submucosal plexus of mouse jejunum using calcium (Ca2+)-imaging. Local VIP application induced Ca2+-transients primarily in neurons and these were inhibited by VPAC1- and VPAC2-antagonists (PG 99-269 and PG 99-465 respectively). These VIP-evoked neural Ca2+-transients were also inhibited by tetrodotoxin (TTX), indicating that they were secondary to action potential generation. Surprisingly, VIP induced Ca2+-transients in glia in the presence of the VPAC2 antagonist. Further, selective VPAC1 receptor activation with the agonist ([K15, R16, L27]VIP(1-7)/GRF(8-27)) predominantly evoked glial responses. However, VPAC1-immunoreactivity did not colocalize with the glial marker glial fibrillary acidic protein (GFAP). Rather, VPAC1 expression was found on cholinergic submucosal neurons and nerve fibers. This suggests that glial responses observed were secondary to neuronal activation. Trains of electrical stimuli were applied to fiber tracts to induce endogenous VIP release. Delayed glial responses were evoked when the VPAC2 antagonist was present. These findings support the presence of an intrinsic VIP/VPAC-initiated neuron-to-glia signaling pathway. VPAC1 agonist-evoked glial responses were inhibited by purinergic antagonists (PPADS and MRS2179), thus demonstrating the involvement of P2Y1 receptors. Collectively, we showed that neurally-released VIP can activate neurons expressing VPAC1 and/or VPAC2 receptors to modulate purine-release onto glia. Selective VPAC1 activation evokes a glial response, whereas VPAC2 receptors may act to inhibit this response. Thus, we identified a component of an enteric neuron-glia circuit that is fine-tuned by endogenous VIP acting through VPAC1- and VPAC2-mediated pathways.
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Affiliation(s)
- Candice Fung
- Department of Physiology, The University of MelbourneParkville, VIC, Australia.,Laboratory for Enteric Neuroscience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), KU LeuvenLeuven, Belgium
| | - Werend Boesmans
- Laboratory for Enteric Neuroscience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), KU LeuvenLeuven, Belgium
| | - Carla Cirillo
- Laboratory for Enteric Neuroscience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), KU LeuvenLeuven, Belgium
| | - Jaime P P Foong
- Department of Physiology, The University of MelbourneParkville, VIC, Australia
| | - Joel C Bornstein
- Department of Physiology, The University of MelbourneParkville, VIC, Australia
| | - Pieter Vanden Berghe
- Laboratory for Enteric Neuroscience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), KU LeuvenLeuven, Belgium
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8
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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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9
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Boesmans W, Martens MA, Weltens N, Hao MM, Tack J, Cirillo C, Vanden Berghe P. Imaging neuron-glia interactions in the enteric nervous system. Front Cell Neurosci 2013; 7:183. [PMID: 24155689 PMCID: PMC3801083 DOI: 10.3389/fncel.2013.00183] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Accepted: 10/01/2013] [Indexed: 12/13/2022] Open
Abstract
The enteric nervous system (ENS) is a network of neurons and glia within the wall of the gastrointestinal tract that is able to control many aspects of digestive function independently from the central nervous system. Enteric glial cells share several features with astrocytes and are closely associated with enteric neurons and their processes both within enteric ganglia, and along interconnecting fiber bundles. Similar to other parts of the nervous system, there is communication between enteric neurons and glia; enteric glial cells can detect neuronal activity and have the machinery to intermediate neurotransmission. However, due to the close contact between these two cell types and the particular characteristics of the gut wall, the recording of enteric glial cell activity in live imaging experiments, especially in the context of their interaction with neurons, is not straightforward. Most studies have used calcium imaging approaches to examine enteric glial cell activity but in many cases, it is difficult to distinguish whether observed transients arise from glial cells, or neuronal processes or varicosities in their vicinity. In this technical report, we describe a number of approaches to unravel the complex neuron-glia crosstalk in the ENS, focusing on the challenges and possibilities of live microscopic imaging in both animal models and human tissue samples.
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Affiliation(s)
- Werend Boesmans
- Laboratory for Enteric NeuroScience (LENS), Translational Research Center for GastroIntestinal Disorders, University of Leuven , Leuven, Belgium ; Translational Research Center for GastroIntestinal Disorders (TARGID), Department of Clinical and Experimental Medicine, University of Leuven , Leuven, Belgium
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10
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Goyal RK, Chaudhury A. Structure activity relationship of synaptic and junctional neurotransmission. Auton Neurosci 2013; 176:11-31. [PMID: 23535140 PMCID: PMC3677731 DOI: 10.1016/j.autneu.2013.02.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Revised: 12/28/2012] [Accepted: 02/18/2013] [Indexed: 12/18/2022]
Abstract
Chemical neurotransmission may include transmission to local or remote sites. Locally, contact between 'bare' portions of the bulbous nerve terminal termed a varicosity and the effector cell may be in the form of either synapse or non-synaptic contact. Traditionally, all local transmissions between nerves and effector cells are considered synaptic in nature. This is particularly true for communication between neurons. However, communication between nerves and other effectors such as smooth muscles has been described as nonsynaptic or junctional in nature. Nonsynaptic neurotransmission is now also increasingly recognized in the CNS. This review focuses on the relationship between structure and function that orchestrate synaptic and junctional neurotransmissions. A synapse is a specialized focal contact between the presynaptic active zone capable of ultrafast release of soluble transmitters and the postsynaptic density that cluster ionotropic receptors. The presynaptic and the postsynaptic areas are separated by the 'closed' synaptic cavity. The physiological hallmark of the synapse is ultrafast postsynaptic potentials lasting milliseconds. In contrast, junctions are juxtapositions of nerve terminals and the effector cells without clear synaptic specializations and the junctional space is 'open' to the extracellular space. Based on the nature of the transmitters, postjunctional receptors and their separation from the release sites, the junctions can be divided into 'close' and 'wide' junctions. Functionally, the 'close' and the 'wide' junctions can be distinguished by postjunctional potentials lasting ~1s and tens of seconds, respectively. Both synaptic and junctional communications are common between neurons; however, junctional transmission is the rule at many neuro-non-neural effectors.
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Affiliation(s)
- Raj K Goyal
- Center for Swallowing and Motility Disorders, GI Division, VA Boston Healthcare System and Harvard Medical School, Boston, USA.
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11
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Sharrad DF, de Vries E, Brookes SJ. Selective expression of α-synuclein-immunoreactivity in vesicular acetylcholine transporter-immunoreactive axons in the guinea pig rectum and human colon. J Comp Neurol 2012; 521:657-76. [DOI: 10.1002/cne.23198] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Revised: 05/03/2012] [Accepted: 07/19/2012] [Indexed: 12/21/2022]
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12
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Sharrad DF, Chen BN, Brookes SJH. Neurochemical coding compared between varicose axons and cell bodies of myenteric neurons in the guinea-pig ileum. Neurosci Lett 2012; 534:171-6. [PMID: 23123789 DOI: 10.1016/j.neulet.2012.10.049] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 10/15/2012] [Accepted: 10/17/2012] [Indexed: 10/27/2022]
Abstract
The discrete functional classes of enteric neurons in the mammalian gastrointestinal tract have been successfully distinguished on the basis of the unique combination of molecules and enzymes in their cell bodies ("chemical coding"). Whether the same chemical coding exists in varicose axons of different functional classes has not been systematically tested. In this study, we quantified the coexistence of markers that define classes of nerve cell bodies in the myenteric plexus of the guinea-pig ileum, in varicose axons of the same neurons. Profound differences between the combinations of immunohistochemical markers in myenteric nerve cell bodies and in their varicosities were identified. These discrepancies were particularly notable for classes of neurons that had previously been classified as cholinergic, based on immunoreactivity for choline acetyltransferase (ChAT) in their cell bodies. To detect cholinergic varicose axons of enteric neurons in this study, we used antiserum against the vesicular acetylcholine transporter (VAChT). ChAT-immunoreactivity has been reported to be consistently co-localized with 5-hydroxytryptamine (5-HT) in interneuronal cell bodies, yet only 29±5% (n=4) of 5-HT-immunoreactive varicosities contained vesicular acetylcholine transporter (VAChT). Somatostatin coexists with ChAT-immunoreactivity in a class of descending interneuron but only 21±1% (n=4) of somatostatin-immunoreactive varicosities were VAChT-immunoreactive. Comparable discrepancies were also noted for non-cholinergic markers. The results suggest that chemical coding of cell bodies does not necessarily reflect chemical coding of varicose axon terminals and that the assumption that nerve cell bodies that contain ChAT are functionally cholinergic may be questionable.
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Affiliation(s)
- Dale F Sharrad
- Department of Human Physiology and Centre for Neuroscience, Flinders Medical Science and Technology, School of Medicine, Flinders University, Bedford Park, South Australia, Australia
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13
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Naumenko N, Pollari E, Kurronen A, Giniatullina R, Shakirzyanova A, Magga J, Koistinaho J, Giniatullin R. Gender-Specific Mechanism of Synaptic Impairment and Its Prevention by GCSF in a Mouse Model of ALS. Front Cell Neurosci 2011; 5:26. [PMID: 22180738 PMCID: PMC3238042 DOI: 10.3389/fncel.2011.00026] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 11/25/2011] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease of motoneurons which progresses differentially in males and females for unknown reason. Here we measured gender differences in pre- and post-synaptic parameters of the neuromuscular transmission in a mutant G93A-SOD1 mouse model of ALS. Using intracellular microelectrode technique we recorded miniature and evoked end-plate potentials (MEPPs and EPPs) in the diaphragm muscle of G93A-SOD1 mice at early symptomatic stage. While no evident alterations in the amplitude of MEPPs was observed in male or female G93A-SOD1 mice, G93A-SOD1 mice displayed dramatically reduced probability of spontaneous acetylcholine release. In contrast, the EPPs evoked by single nerve stimulation had unchanged amplitude and quantal content. In males, but not females, this was accompanied by reduced readily releasable transmitter pool. Transmitter release in both sexes was sensitive to the inhibitory action of reactive oxygen species (ROS), but the production of ROS was increased in the spinal cords of male but not female G93A-SOD1 mice. Treatment with granulocyte colony stimulating factor (GCSF), which we previously found to be beneficial in males, attenuated the increased ROS production indicating involvement of the antioxidant mechanisms and improved ALS-induced synaptic dysfunctions only in males being ineffective in females. Consistent with our findings at synaptic level, GCSF did not change the survival rate or motor performance of female ALS mice. In summary, neuromuscular transmission in ALS mice is impaired at early symptomatic stage when a dramatic presynaptic decline of spontaneous release occurs. Beneficial effects of GCSF treatment on survival in males may be explained by GCSF-improved presynaptic functions in male G93A-SOD1 mice. Development of efficient treatment strategies for ALS may need to be directed in a gender-specific manner.
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Affiliation(s)
- Nikolay Naumenko
- Department of Neurobiology, A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland Kuopio, Finland
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Laranjeira C, Sandgren K, Kessaris N, Richardson W, Potocnik A, Vanden Berghe P, Pachnis V. Glial cells in the mouse enteric nervous system can undergo neurogenesis in response to injury. J Clin Invest 2011; 121:3412-24. [PMID: 21865647 DOI: 10.1172/jci58200] [Citation(s) in RCA: 292] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Accepted: 06/27/2011] [Indexed: 01/13/2023] Open
Abstract
The enteric nervous system (ENS) in mammals forms from neural crest cells during embryogenesis and early postnatal life. Nevertheless, multipotent progenitors of the ENS can be identified in the adult intestine using clonal cultures and in vivo transplantation assays. The identity of these neurogenic precursors in the adult gut and their relationship to the embryonic progenitors of the ENS are currently unknown. Using genetic fate mapping, we here demonstrate that mouse neural crest cells marked by SRY box-containing gene 10 (Sox10) generate the neuronal and glial lineages of enteric ganglia. Most neurons originated from progenitors residing in the gut during mid-gestation. Afterward, enteric neurogenesis was reduced, and it ceased between 1 and 3 months of postnatal life. Sox10-expressing cells present in the myenteric plexus of adult mice expressed glial markers, and we found no evidence that these cells participated in neurogenesis under steady-state conditions. However, they retained neurogenic potential, as they were capable of generating neurons with characteristics of enteric neurons in culture. Furthermore, enteric glia gave rise to neurons in vivo in response to chemical injury to the enteric ganglia. Our results indicate that despite the absence of constitutive neurogenesis in the adult gut, enteric glia maintain limited neurogenic potential, which can be activated by tissue dissociation or injury.
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Affiliation(s)
- Catia Laranjeira
- Division of Molecular Neurobiology, Medical Research Council National Institute for Medical Research, London, United Kingdom
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Wang W, Jia H, Zhang H, Chen Q, Zhang T, Bai Y, Yuan Z. Abnormal innervation patterns in the anorectum of ETU-induced fetal rats with anorectal malformations. Neurosci Lett 2011; 495:88-92. [DOI: 10.1016/j.neulet.2011.02.057] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Revised: 02/15/2011] [Accepted: 02/21/2011] [Indexed: 10/18/2022]
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Harrington AM, Lee M, Ong SY, Yong E, Farmer P, Peck CJ, Chow CW, Hutson JM, Southwell BR. Immunoreactivity for high-affinity choline transporter colocalises with VAChT in human enteric nervous system. Cell Tissue Res 2010; 341:33-48. [PMID: 20490865 DOI: 10.1007/s00441-010-0981-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 04/08/2010] [Indexed: 01/08/2023]
Abstract
Cholinergic nerves are identified by labelling molecules in the ACh synthesis, release and destruction pathway. Recently, antibodies against another molecule in this pathway have been developed. Choline reuptake at the synapse occurs via the high-affinity choline transporter (CHT1). CHT1 immunoreactivity is present in cholinergic nerve fibres containing vesicular acetylcholine transporter (VAChT) in the human and rat central nervous system and rat enteric nervous system. We have examined whether CHT1 immunoreactivity is present in nerve fibres in human intestine and whether it is colocalised with markers of cholinergic, tachykinergic or nitrergic circuitry. Human ileum and colon were fixed, sectioned and processed for fluorescence immunohistochemistry with antibodies against CHT1, class III beta-tubulin (TUJ1), synaptophysin, common choline acetyl-transferase (cChAT), VAChT, nitric oxide synthase (NOS), substance P (SP) and vasoactive intestinal peptide (VIP). CHT1 immunoreactivity was present in many nerve fibres in the circular and longitudinal muscle, myenteric and submucosal ganglia, submucosa and mucosa in human colon and ileum and colocalised with immunoreactivity for TUJ1 and synaptophysin confirming its presence in nerve fibres. In nerve fibres in myenteric ganglia and muscle, CHT1 immunoreactivity colocalised with immunoreactivity for VAChT and cChAT. Some colocalisation occurred with SP immunoreactivity, but little with immunoreactivity for VIP or NOS. In the mucosa, CHT1 immunoreactivity colocalised with that for VIP and SP in nerve fibres and was also present in vascular nerve fibres in the submucosa and on epithelial cells on the luminal border of crypts. The colocalisation of CHT1 immunoreactivity with VAChT immunoreactivity in cholinergic enteric nerves in the human bowel thus suggests that CHT1 represents another marker of cholinergic nerves.
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Affiliation(s)
- Andrea M Harrington
- F Douglas Stephens Surgical Research Laboratory, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
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Paramonova NM, Sotnikov OS. Cytoplasmic Syncytial Connections Between Neuron Bodies in the CNS of Adult Animals. ACTA ACUST UNITED AC 2009; 40:73-7. [DOI: 10.1007/s11055-009-9221-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Revised: 04/04/2008] [Indexed: 10/20/2022]
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Boesmans W, Ameloot K, van den Abbeel V, Tack J, Vanden Berghe P. Cannabinoid receptor 1 signalling dampens activity and mitochondrial transport in networks of enteric neurones. Neurogastroenterol Motil 2009; 21:958-e77. [PMID: 19374636 DOI: 10.1111/j.1365-2982.2009.01300.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cannabinoid (CB) receptors are expressed in the enteric nervous system (ENS) and CB(1) receptor activity slows down motility and delays gastric emptying. This receptor system has become an important target for GI-related drug development such as in obesity treatment. The aim of the study was to investigate how CB(1) ligands and antagonists affect ongoing activity in enteric neurone networks, modulate synaptic vesicle cycling and influence mitochondrial transport in nerve processes. Primary cultures of guinea-pig myenteric neurones were loaded with different fluorescent markers: Fluo-4 to measure network activity, FM1-43 to image synaptic vesicles and Mitotracker green to label mitochondria. Synaptic vesicle cluster density was assessed by immunohistochemistry and expression of CB(1) receptors was confirmed by RT-PCR. Spontaneous network activity, displayed by both excitatory and inhibitory neurones, was significantly increased by CB(1) receptor antagonists (AM-251 and SR141716), abolished by CB(1) activation (methanandamide, mAEA) and reduced by two different inhibitors (arachidonylamide serotonin, AA-5HT and URB597) of fatty acid amide hydrolase. Antagonists reduced the number of synaptic vesicles that were recycled during an electrical stimulus. CB(1) agonists (mAEA and WIN55,212) reduced and antagonists enhanced the fraction of transported mitochondria in enteric nerve fibres. We found immunohistochemical evidence for an enhancement of synaptophysin-positive release sites with SR141716, while WIN55,212 caused a reduction. The opposite effects of agonists and antagonists suggest that enteric nerve signalling is under the permanent control of CB(1) receptor activity. Using inhibitors of the endocannabinoid degrading enzyme, we were able to show there is endogenous production of a CB ligand in the ENS.
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Affiliation(s)
- W Boesmans
- Center for Gastroenterological Research, KULeuven, Leuven, Belgium
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Vanden Berghe P, Tack J, Boesmans W. Highlighting synaptic communication in the enteric nervous system. Gastroenterology 2008; 135:20-3. [PMID: 18555020 DOI: 10.1053/j.gastro.2008.06.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Sharkey KA. Tyrosine hydroxylase in the stalk-median eminence and posterior pituitary is inactivated only during the plateau phase of the preovulatory prolactin surge. Endocrinology 1989; 125:918-25. [PMID: 25689252 DOI: 10.1172/jci76303] [Citation(s) in RCA: 135] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
This study examined changes in the activity of tyrosine hydroxylase (TH) in the stalk-median eminence (SME) and posterior pituitary (PP) during the preovulatory PRL surge. Immature female rats were injected with PMSG on day 28. Blood PRL levels were low on the morning of day 30, rose to a peak from 1400-1600 h, remained at a lower plateau from 1800-2400 h, and declined to basal levels on the morning of day 31. SME, PP, and striatum were removed from PMSG-treated rats at selected times during the periovulatory period and from age-matched control rats. TH activity was determined in tissue homogenates by a coupled hydroxylation-decarboxylation assay. Apparent Km and maximum velocity values with respect to 6-methyl tetrahydropterine were estimated from substrate saturation curves. The kinetic parameters for TH in either the SME or the PP of control rats were similar at 1100 and 1800 h on day 30. However, the apparent Km in both tissues was significantly lower than that in the striatum. The affinity of TH in the SME and PP was unchanged before and during the peak phase of the PRL surge, reduced significantly during the late plateau, and returned to presurge levels in the morning of day 31. TH activity in the striatum was similar at all times examined. To determine the state of activation of the enzyme, tissue homogenates were preincubated with cAMP, ATP, and magnesium. TH activity in the SME during the peak phase was unchanged by cAMP, and that in the PP was modestly increased. The relatively inactive enzyme in both tissues during the plateau phase was markedly activated by a cAMP-dependent mechanism. The low affinity of striatal TH was greatly increased by cAMP at both times. These data suggest that TH in the SME and PP exists in an activated state most of the time and is transiently inactivated during the plateau phase of the PRL surge. In contrast, TH in the striatum is relatively inactive in the basal state and is not affected by hormonal changes induced by PMSG. We conclude that the peak PRL surge occurs in spite of active dopamine (DA) neurons, suggesting that it is generated by a nondopaminergic mechanism. Decreased TH activity in DA neurons in the SME and PP may prolong the PRL surge during the plateau phase, whereas increased DA activity coincides with the termination of the surge.
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