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Herath M, Cho E, Marklund U, Franks AE, Bornstein JC, Hill-Yardin EL. Quantitative Spatial Analysis of Neuroligin-3 mRNA Expression in the Enteric Nervous System Reveals a Potential Role in Neuronal-Glial Synapses and Reduced Expression in Nlgn3R451C Mice. Biomolecules 2023; 13:1063. [PMID: 37509099 PMCID: PMC10377306 DOI: 10.3390/biom13071063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 06/23/2023] [Accepted: 06/25/2023] [Indexed: 07/30/2023] Open
Abstract
Mutations in the Neuroligin-3 (Nlgn3) gene are implicated in autism spectrum disorder (ASD) and gastrointestinal (GI) dysfunction, but cellular Nlgn3 expression in the enteric nervous system remains to be characterised. We combined RNAScope in situ hybridization and immunofluorescence to measure Nlgn3 mRNA expression in cholinergic and VIP-expressing submucosal neurons, nitrergic and calretinin-containing myenteric neurons and glial cells in both WT and Nlgn3R451C mutant mice. We measured Nlgn3 mRNA neuronal and glial expression via quantitative three-dimensional image analysis. To validate dual RNAScope/immunofluorescence data, we interrogated available single-cell RNA sequencing (scRNASeq) data to assess for Nlgn3, Nlgn1, Nlgn2 and their binding partners, Nrxn1-3, MGDA1 and MGDA2, in enteric neural subsets. Most submucosal and myenteric neurons expressed Nlgn3 mRNA. In contrast to other Nlgns and binding partners, Nlgn3 was strongly expressed in enteric glia, suggesting a role for neuroligin-3 in mediating enteric neuron-glia interactions. The autism-associated R451C mutation reduces Nlgn3 mRNA expression in cholinergic but not in VIPergic submucosal neurons. In the myenteric plexus, Nlgn3 mRNA levels are reduced in calretinin, nNOS-labelled neurons and S100 β -labelled glia. We provide a comprehensive cellular profile for neuroligin-3 expression in ileal neuronal subpopulations of mice expressing the R451C autism-associated mutation in Nlgn3, which may contribute to the understanding of the pathophysiology of GI dysfunction in ASD.
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Affiliation(s)
- Madushani Herath
- Department of Anatomy & Physiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Ellie Cho
- Biological Optical Microscopy Platform, University of Melbourne, Parkville, VIC 3010, Australia
| | - Ulrika Marklund
- Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, 171 77 Stockholm, Sweden
| | - Ashley E Franks
- Department of Microbiology, Anatomy Physiology & Pharmacology, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, VIC 3086, Australia
| | - Joel C Bornstein
- Department of Anatomy & Physiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Elisa L Hill-Yardin
- School of Health and Biomedical Sciences, STEM College, RMIT University, Bundoora, VIC 3083, Australia
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Thomasi B, Gulbransen B. Mini-review: Intercellular communication between enteric glia and neurons. Neurosci Lett 2023; 806:137263. [PMID: 37085112 PMCID: PMC10150911 DOI: 10.1016/j.neulet.2023.137263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 04/13/2023] [Accepted: 04/17/2023] [Indexed: 04/23/2023]
Abstract
The enteric nervous system is a dense network of enteric neurons and glia housed in the gastrointestinal tract. This system is responsible for performing several functions that enable digestion as well as maintaining gut homeostasis through diverse signaling processes including those that arise from interactions with the immune system. Bidirectional communication between enteric neurons and enteric glia has gained increased attention for playing essential roles in enteric nervous system function. Neuronal mediators such as neurotransmitters stimulate enteric glia and subsequent gliotransmission processes refine neuronal signaling during intestinal motor control. In this mini-review, we present and discuss the basis of intercellular signaling between neurons and glia in the enteric nervous system and the relevance of these interactions to gut function.
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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: 36] [Impact Index Per Article: 36.0] [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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Li Y, Li YR, Jin Y, Li MY, Zhang Q, Cao J, Li F, Zhang H, Chen J, Li YQ. Involvement of enteric glial cells in colonic motility in a rat model of irritable bowel syndrome with predominant diarrhea. J Chem Neuroanat 2023; 128:102235. [PMID: 36669707 DOI: 10.1016/j.jchemneu.2023.102235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 01/15/2023] [Accepted: 01/16/2023] [Indexed: 01/19/2023]
Abstract
The enteric nervous system (ENS) is one of the important systems that regulate gastrointestinal function. The ENS is made up of enteric glial cells (EGCs) and neurons. For a long time, it was believed that the function of EGCs was only to give structural support to neurons. However, recent evidence indicates EGCs are involved in most gut functions, including the development and plasticity of the ENS, epithelial barrier, and motility. However, it remains unclear whether EGCs have the potential to modify colonic motility following irritable bowel syndrome (IBS) with predominant diarrhea (IBS-D). This study aimed to investigate changes in EGCs during IBS-D and assessed the effects of manipulating EGCs. An IBS-D rat model was constructed using acetic acid and restraint stress, and DL-fluorocitric acid (FC), an inhibitor of EGCs, was administered. The changes in EGCs and colonic motility were studied by employing techniques comprising morphological, molecular biological and functional experiments. The results showed significant activation of EGCs in the myenteric plexus (MP) of the IBS-D-induced rat colon with accelerated colonic motility. FC significantly reduced the activation of EGCs and colonic motility caused by acetic acid and restraint stress. Hypercontraction of the colon caused by IBS-D may be associated with activation of EGCs in the MP of the colon and this was prevented by FC. Therefore, regulating colon hypercontraction through interference with the activation of EGCs has significant prospects for clinical application to alleviate diarrhea in patients with IBS-D.
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Affiliation(s)
- Yan Li
- Department of Anatomy, Histology and Embryology and K. K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an 710032, China; Department of Geriatrics, Tangdu Hospital, The Fourth Military Medical University, Xi'an 710038, China; Department of Human Anatomy, Basic Medical College, Zunyi Medical University, Zunyi 563006, China
| | - Yan-Rong Li
- Department of Gastroenterology, The First Affiliated Hospital of Jinzhou Medical University, Jinzhou 121000, China
| | - Yuan Jin
- Department of Human Anatomy, Basic Medical College, Zunyi Medical University, Zunyi 563006, China
| | - Meng-Ying Li
- Department of Endocrinology and Metabolism, Xijing Hospital, The Fourth Medical University, Xi'an 710032, China
| | - Qian Zhang
- Department of Human Anatomy, Basic Medical College, Zunyi Medical University, Zunyi 563006, China
| | - Jing Cao
- Department of Human Anatomy, College of Preclinical Medical Sciences, Zhengzhou University, Zhengzhou 450001, China
| | - Fei Li
- Department of Anatomy, Histology and Embryology and K. K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an 710032, China
| | - Hua Zhang
- Department of Geriatrics, Tangdu Hospital, The Fourth Military Medical University, Xi'an 710038, China.
| | - Jing Chen
- Department of Anatomy, Histology and Embryology and K. K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an 710032, China.
| | - Yun-Qing Li
- Department of Anatomy, Histology and Embryology and K. K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an 710032, China; Department of Geriatrics, Tangdu Hospital, The Fourth Military Medical University, Xi'an 710038, China; Department of Human Anatomy, Basic Medical College, Zunyi Medical University, Zunyi 563006, China; Key Laboratory of Brain Science Research and Transformation in Tropical Environment of Hainan Province, Hainan Medical University, Haikou 571199, China.
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Group I Metabotropic Glutamate Receptors Modulate Motility and Enteric Neural Activity in the Mouse Colon. Biomolecules 2023; 13:biom13010139. [PMID: 36671524 PMCID: PMC9856182 DOI: 10.3390/biom13010139] [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: 11/18/2022] [Revised: 01/04/2023] [Accepted: 01/05/2023] [Indexed: 01/12/2023] Open
Abstract
Glutamate is the major excitatory neurotransmitter in the central nervous system, and there is evidence that Group-I metabotropic glutamate receptors (mGlu1 and mGlu5) have established roles in excitatory neurotransmission and synaptic plasticity. While glutamate is abundantly present in the gut, it plays a smaller role in neurotransmission in the enteric nervous system. In this study, we examined the roles of Group-I mGlu receptors in gastrointestinal function. We investigated the expression of Grm1 (mGlu1) and Grm5 (mGlu5) in the mouse myenteric plexus using RNAscope in situ hybridization. Live calcium imaging and motility analysis were performed on ex vivo preparations of the mouse colon. mGlu5 was found to play a role in excitatory enteric neurotransmission, as electrically-evoked calcium transients were sensitive to the mGlu5 antagonist MPEP. However, inhibition of mGlu5 activity did not affect colonic motor complexes (CMCs). Instead, inhibition of mGlu1 using BAY 36-7620 reduced CMC frequency but did not affect enteric neurotransmission. These data highlight complex roles for Group-I mGlu receptors in myenteric neuron activity and colonic function.
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Almeida PP, Valdetaro L, Thomasi BBDM, Stockler-Pinto MB, Tavares-Gomes AL. High-fat diets on the enteric nervous system: Possible interactions and mechanisms underlying dysmotility. Obes Rev 2022; 23:e13404. [PMID: 34873814 DOI: 10.1111/obr.13404] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 10/25/2021] [Accepted: 11/15/2021] [Indexed: 01/09/2023]
Abstract
Obesity is a chronic disease that affects various physiological systems. Among them, the gastrointestinal tract appears to be a main target of this disease. High-fat diet (HFD) animal models can help recapitulate the classic signs of obesity and present a series of gastrointestinal alterations, mainly dysmotility. Because intestinal motility is governed by the enteric nervous system (ENS), enteric neurons, and glial cells have been studied in HFD models. Given the importance of the ENS in general gut physiology, this review aims to discuss the relationship between HFD-induced neuroplasticity and gut dysmotility observed in experimental models. Furthermore, we highlight components of the gut environment that might influence enteric neuroplasticity, including gut microbiota, enteric glio-epithelial unit, serotonin release, immune cells, and disturbances such as inflammation and oxidative stress.
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Affiliation(s)
| | - Luisa Valdetaro
- Postgraduate Program in Neurosciences, Fluminense Federal University, Niterói, Brazil
| | | | - Milena Barcza Stockler-Pinto
- Postgraduate Program in Cardiovascular Sciences, Fluminense Federal University, Niterói, Brazil.,Postgraduate Program in Nutrition Sciences, Fluminense Federal University, Niterói, Brazil
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Electroacupuncture Alleviates Visceral Hypersensitivity in IBS-D Rats by Inhibiting EGCs Activity through Regulating BDNF/TrkB Signaling Pathway. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2022; 2022:2497430. [PMID: 35198032 PMCID: PMC8860523 DOI: 10.1155/2022/2497430] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 01/17/2022] [Indexed: 02/05/2023]
Abstract
Objective To determine whether electroacupuncture (EA) could alleviate visceral hypersensitivity in diarrhea-predominant irritable bowel syndrome (IBS-D) rats by inhibiting EGCs activity via the BDNF/TrkB signaling pathway. Methods Sprague Dawley rats were randomly divided to a control group (n = 8) and a model preparation group (n = 32), which received Senna solution by gavage and CUMS (chronic unpredictable mild stress) for 14 consecutive days and was further divided to a Model group, an EA group (only electroacupuncture), an EA + TrkB agonist group (electroacupuncture and TrkB), and an EA + DMSO group (electroacupuncture and DMSO, n = 8 for each). Rats in the three EA groups were acupunctured at ST25, ST36, and LR3 for 20 min every day for 14 days. Abdominal withdrawal reflex (AWR) was used to quantify visceral sensitivity; reverse transcription polymerase chain reaction (RT-PCR) and double immunofluorescent staining were used to detect the colocalized expression of GFAP/BDNF and GFAP/TrkB. Western Blot (WB) was used to detect the expression of PLC and SP in the colon. Flow cytometry was used to detect the expression of Ca2+. Results EA effectively alleviated visceral hypersensitivity in IBS-D rats (P < 0.05). Compared to the control group, the expression of BDNF, TrkB, PLC, SP, and Ca2+ and the colocalized expression of GFAP/BDNF and GFAP/TrkB increased in the Model group (P < 0.05), while all these parameters decreased in the EA group following EA intervention (P < 0.05). In addition, no significant difference was found between the EA + TrkB agonist group and the control group (P > 0.05). Conclusions EA alleviates visceral hypersensitivity of IBS-D rats possibly by inhibiting the activity of EGCs through the BDNF/TrkB-PLC-Ca2+ signaling pathway in the colon.
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Ahmadzai MM, McClain JL, Dharshika C, Seguella L, Giancola F, De Giorgio R, Gulbransen BD. LPAR1 regulates enteric nervous system function through glial signaling and contributes to chronic intestinal pseudo-obstruction. J Clin Invest 2022; 132:149464. [PMID: 35166239 PMCID: PMC8843750 DOI: 10.1172/jci149464] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 12/21/2021] [Indexed: 12/30/2022] Open
Abstract
Gastrointestinal motility disorders involve alterations to the structure and/or function of the enteric nervous system (ENS) but the causal mechanisms remain unresolved in most cases. Homeostasis and disease in the ENS are processes that are regulated by enteric glia. Signaling mediated through type I lysophosphatidic acid receptors (LPAR1) has recently emerged as an important mechanism that contributes to disease, in part, through effects on peripheral glial survival and function. Enteric glia express LPAR1 but its role in ENS function and motility disorders is unknown. We used a combination of genetic, immunohistochemical, calcium imaging, and in vivo pharmacological approaches to investigate the role of LPAR1 in enteric glia. LPAR1 was enriched in enteric glia in mice and humans and LPA stimulated intracellular calcium responses in enteric glia, subsequently recruiting activity in a subpopulation of myenteric neurons. Blocking LPAR1 in vivo with AM966 attenuated gastrointestinal motility in mice and produced marked enteric neuro- and gliopathy. Samples from humans with chronic intestinal pseudo-obstruction (CIPO), a severe motility disorder, showed reduced glial LPAR1 expression in the colon and ileum. These data suggest that enteric glial LPAR1 signaling regulates gastrointestinal motility through enteric glia and could contribute to severe motility disorders in humans such as CIPO.
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Affiliation(s)
- Mohammad M Ahmadzai
- Department of Physiology, Neuroscience Program.,College of Osteopathic Medicine, and
| | | | - Christine Dharshika
- Department of Physiology, Neuroscience Program.,College of Human Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Luisa Seguella
- Department of Physiology, Neuroscience Program.,Department of Physiology and Pharmacology "V. Erspamer", Sapienza University of Rome, Rome, Italy
| | - Fiorella Giancola
- Department of Translational Medicine, University of Ferrara, Ferrara, Italy.,St. Orsola-Malpighi Hospital, Bologna, Italy
| | - Roberto De Giorgio
- Department of Translational Medicine, University of Ferrara, Ferrara, Italy
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Almeida PPD, Thomasi BBDM, Costa NDS, Valdetaro L, Pereira AD, Gomes ALT, Stockler-Pinto MB. Brazil Nut ( Bertholletia excelsa H.B.K) Retards Gastric Emptying and Modulates Enteric Glial Cells in a Dose-Dependent Manner. JOURNAL OF THE AMERICAN NUTRITION ASSOCIATION 2022; 41:157-165. [PMID: 33301378 DOI: 10.1080/07315724.2020.1852981] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 11/04/2020] [Accepted: 11/15/2020] [Indexed: 12/16/2022]
Abstract
BACKGROUND The role of food and nutrients in the regulation of enteric glial cell functions is unclear. Some foods influence enteric neurophysiology and can affect glial cell functions that include regulation of the intestinal barrier, gastric emptying, and colonic transit. Brazil nuts are the most abundant natural source of selenium, unsaturated fatty acids, fibers, and polyphenols. OBJECTIVE The study investigated the effects of a Brazil nut-enriched diet on enteric glial cells and gastrointestinal transit. METHODS Two-month-old male Wistar rats were randomized to a standard diet (control group, CG), standard diet containing 5% (wt/wt) Brazil nut (BN5), and standard diet containing 10% (wt/wt) Brazil nut (BN10) (n = 9 per group). After eight weeks, the animals underwent constipation and gastric emptying tests to assess motility. Evaluations of colonic immunofluorescence staining for glial fibrillary acidic protein (GFAP) and myenteric ganglia area were performed. RESULTS The BN5 group showed increased weight gain while the BN10 group did not (p < 0.0001). The BN10 group showed higher gastric residue amounts compared to the other groups (p = 0.0008). The colon exhibited an increase in GFAP immunoreactivity in the BN5 group compared to that in the other groups (p = 0.0016), and the BN10 group presented minor immunoreactivity compared to the CG (p = 0.04). The BN10 group presented a minor ganglia area compared to the CG (p = 0.0155). CONCLUSION The Brazil nut-enriched diet modified the gastric residual, colonic GFAP immunoreactivity, and myenteric ganglia area after eight weeks in healthy male Wistar rats.
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Affiliation(s)
| | | | - Nathalia da Silva Costa
- Postgraduate Program in Cardiovascular Sciences, Fluminense Federal University (UFF), Niterói, RJ, Brazil
| | - Luisa Valdetaro
- Postgraduate Program in Neurosciences, Fluminense Federal University (UFF), Niterói, RJ, Brazil
| | - Aline D'Avila Pereira
- Postgraduate Program in Medical Sciences, Fluminense Federal University (UFF), Niterói, RJ, Brazil
| | - Ana Lúcia Tavares Gomes
- Postgraduate Program in Neurosciences, Fluminense Federal University (UFF), Niterói, RJ, Brazil
| | - Milena Barcza Stockler-Pinto
- Postgraduate Program in Cardiovascular Sciences, Fluminense Federal University (UFF), Niterói, RJ, Brazil
- Postgraduate Program in Nutrition Sciences, Fluminense Federal University (UFF), Niterói, RJ, Brazil
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10
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Carbone SE. Neurons, Macrophages, and Glia: The Role of Intercellular Communication in the Enteric Nervous System. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1383:251-258. [PMID: 36587164 DOI: 10.1007/978-3-031-05843-1_24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Neurons of the enteric nervous system (ENS) are the primary controllers of gastrointestinal functions. Although the ENS has been the central focus of research areas such as motility, this has now expanded to include the modulatory roles that non-neuronal cells have on neuronal function. This review discusses how enteric glia (EGC) and resident muscularis macrophages (mMacs) influence ENS communication. It highlights how the understanding of neuroglia interactions has extended beyond EGCs responding to exogenously applied neurotransmitters. Proposed mechanisms for neuron-EGC and glio-glia communication are discussed. The significance of these interactions is evidenced by gut functions that rely on these processes. mMacs are commonly known for their roles as immune cells which sample and respond to changes in the tissue environment. However, a more recent theory suggests that mMacs and enteric neurons are mutually dependent for their maintenance and function. This review summarizes the supportive and contradictory evidence for this theory, including potential mechanisms for mMac-neuron interaction. The need for a more thorough classification scheme to define how the "state" of mMacs relates to neuron loss or impaired function in disease is discussed. Despite the growing literature suggesting EGCs and mMacs have supportive or modulatory roles in ENS communication and gut function, conflicting evidence from different groups suggests more investigation is required. A broader understanding of why enteric neurons may need assistance from EGCs and mMacs in neurotransmission is still missing.
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Affiliation(s)
- Simona Elisa Carbone
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, VIC, Australia.
- Monash University, Parkville, VIC, Australia.
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11
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Circuit-specific enteric glia regulate intestinal motor neurocircuits. Proc Natl Acad Sci U S A 2021; 118:2025938118. [PMID: 34593632 PMCID: PMC8501758 DOI: 10.1073/pnas.2025938118] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/18/2021] [Indexed: 12/19/2022] Open
Abstract
Glia in the central nervous system exert precise spatial and temporal regulation over neural circuitry on a synapse-specific basis, but it is unclear if peripheral glia share this exquisite capacity to sense and modulate circuit activity. In the enteric nervous system (ENS), glia control gastrointestinal motility through bidirectional communication with surrounding neurons. We combined glial chemogenetics with genetically encoded calcium indicators expressed in enteric neurons and glia to study network-level activity in the intact myenteric plexus of the proximal colon. Stimulation of neural fiber tracts projecting in aboral, oral, and circumferential directions activated distinct populations of enteric glia. The majority of glia responded to both oral and aboral stimulation and circumferential pathways, while smaller subpopulations were activated only by ascending and descending pathways. Cholinergic signaling functionally specifies glia to the descending circuitry, and this network plays an important role in repressing the activity of descending neural pathways, with some degree of cross-inhibition imposed upon the ascending pathway. Glial recruitment by purinergic signaling functions to enhance activity within ascending circuit pathways and constrain activity within descending networks. Pharmacological manipulation of glial purinergic and cholinergic signaling differentially altered neuronal responses in these circuits in a sex-dependent manner. Collectively, our findings establish that the balance between purinergic and cholinergic signaling may differentially control specific circuit activity through selective signaling between networks of enteric neurons and glia. Thus, enteric glia regulate the ENS circuitry in a network-specific manner, providing profound insights into the functional breadth and versatility of peripheral glia.
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12
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Wang YJ, Jia QL, Li L, Wang XX, Ling JH. Progress in understanding of relationship between gut microbiota and gastrointestinal motility. Shijie Huaren Xiaohua Zazhi 2021; 29:1020-1025. [DOI: 10.11569/wcjd.v29.i17.1020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Gastrointestinal motility disorders are a group of common clinical disorders in which abnormal gastrointestinal motility is the major pathogenesis, including irritable bowel syndrome, functional dyspepsia, and diabetic gastroparesis. With the rapid development of microbial sequencing technology in the past 10 years, the understanding of the gut microbiota has greatly improved, and it is generally found that patients with gastrointestinal motility diseases have gut microbiota disorders. Some progress has been made on the correlation between gut microbiota and gastrointestinal motility. This review aims to elucidate the relationship between gut microbiota and gastrointestinal motility and the mechanism of their interaction.
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Affiliation(s)
- Yu-Jiao Wang
- Department of Gastroenterology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200021, China
| | - Qing-Ling Jia
- Department of Gastroenterology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200021, China
| | - Li Li
- Department of Gastroenterology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200021, China
| | - Xiang-Xiang Wang
- Department of Gastroenterology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200021, China
| | - Jiang-Hong Ling
- Department of Gastroenterology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200021, China
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13
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Abstract
Glia, the non-neuronal cells of the nervous system, were long considered secondary cells only necessary for supporting the functions of their more important neuronal neighbors. Work by many groups over the past two decades has completely overturned this notion, revealing the myriad and vital functions of glia in nervous system development, plasticity, and health. The largest population of glia outside the brain is in the enteric nervous system, a division of the autonomic nervous system that constitutes a key node of the gut-brain axis. Here, we review the latest in the understanding of these enteric glia in mammals with a focus on their putative roles in human health and disease.
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Affiliation(s)
- Harry J. Rosenberg
- Department of Pathology, Beth Israel Deaconess Medical Center, Boston, MA 02115, USA
- Department of Pediatrics, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Meenakshi Rao
- Department of Pediatrics, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
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14
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Seguella L, Gulbransen BD. Enteric glial biology, intercellular signalling and roles in gastrointestinal disease. Nat Rev Gastroenterol Hepatol 2021; 18:571-587. [PMID: 33731961 PMCID: PMC8324524 DOI: 10.1038/s41575-021-00423-7] [Citation(s) in RCA: 110] [Impact Index Per Article: 36.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/28/2021] [Indexed: 02/07/2023]
Abstract
One of the most transformative developments in neurogastroenterology is the realization that many functions normally attributed to enteric neurons involve interactions with enteric glial cells: a large population of peripheral neuroglia associated with enteric neurons throughout the gastrointestinal tract. The notion that glial cells function solely as passive support cells has been refuted by compelling evidence that demonstrates that enteric glia are important homeostatic cells of the intestine. Active signalling mechanisms between enteric glia and neurons modulate gastrointestinal reflexes and, in certain circumstances, function to drive neuroinflammatory processes that lead to long-term dysfunction. Bidirectional communication between enteric glia and immune cells contributes to gastrointestinal immune homeostasis, and crosstalk between enteric glia and cancer stem cells regulates tumorigenesis. These neuromodulatory and immunomodulatory roles place enteric glia in a unique position to regulate diverse gastrointestinal disease processes. In this Review, we discuss current concepts regarding enteric glial development, heterogeneity and functional roles in gastrointestinal pathophysiology and pathophysiology, with a focus on interactions with neurons and immune cells. We also present a working model to differentiate glial states based on normal function and disease-induced dysfunctions.
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Affiliation(s)
- Luisa Seguella
- Department of Physiology and Pharmacology "V. Erspamer", Sapienza University of Rome, Rome, Italy
- Department of Physiology, Neuroscience Program, Michigan State University, East Lansing, MI, USA
| | - Brian D Gulbransen
- Department of Physiology, Neuroscience Program, Michigan State University, East Lansing, MI, USA.
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15
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Li Y, Wang Y, Chang H, Cheng B, Miao J, Li S, Hu H, Huang L, Wang Q. Inhibitory Effects of Dexmedetomidine and Propofol on Gastrointestinal Tract Motility Involving Impaired Enteric Glia Ca 2+ Response in Mice. Neurochem Res 2021; 46:1410-1422. [PMID: 33656693 DOI: 10.1007/s11064-021-03280-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Revised: 02/20/2021] [Accepted: 02/20/2021] [Indexed: 12/31/2022]
Abstract
Propofol and dexmedetomidine are popular used for sedation in ICU, however, inadequate attention has been paid to their effect on gastrointestinal tract (GIT) motility. Present study aimed to compare the effect of propofol and dexmedetomidine on GIT motility at parallel level of sedation and explore the possible mechanism. Male C57BL/6 mice (8-10 weeks) were randomly divided into control, propofol and dexmedetomidine group. After intraperitoneal injection of propofol or dexmedetomidine, comparable sedative level was confirmed by sedative score, physiological parameters and electroencephalogram (EEG). Different segments of GIT motility in vivo (gastric emptying, small intestine transit, distal colon bead expulsion, stool weight and number of fecal pellets, gastrointestinal transit and whole gut transit time) and colonic migrating motor complexes (CMMCs) pattern in vitro were evaluated. The Ca2+ response of primary enteric glia was examined under the treatment of propofol or dexmedetomidine. There is little difference in physiological parameters and composite permutation entropy index (CPEI) between administration of 50 mg/kg propofol and 40 μg/kg dexmedetomidine, indicated that parallel level of sedation was reached. Data showed that propofol and dexmedetomidine had significantly inhibitory effect on GIT motility while dexmedetomidine was stronger. Also, the amplitude (ΔF/F0) of Ca2+ response in primary enteric glia was attenuated after treated with the sedatives while the effect of dexmedetomidine was greater than propofol. These findings demonstrated that dexmedetomidine caused stronger inhibitory effects on GIT motility in sedative mice, which may involve impaired Ca2+ response in enteric glia. Hence, dexmedetomidine should be carefully applied especially for potential GIT dysmotility patient.
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Affiliation(s)
- Yansong Li
- Department of Anesthesiology & Center for Brain Science, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Yubo Wang
- School of Life Science and Technology, Xidian University, Xi'an, 710061, Shaanxi, China
| | - Haiqing Chang
- Department of Anesthesiology & Center for Brain Science, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Bo Cheng
- Department of Anesthesiology & Center for Brain Science, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Jiwen Miao
- Department of Anesthesiology & Center for Brain Science, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Shuang Li
- Department of Anesthesiology & Center for Brain Science, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Hao Hu
- Department of Pharmacology, School of Basic Medical Sciences, Health Science Center, Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Liyu Huang
- School of Life Science and Technology, Xidian University, Xi'an, 710061, Shaanxi, China
| | - Qiang Wang
- Department of Anesthesiology & Center for Brain Science, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China.
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16
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Broadhead MJ, Miles GB. A common role for astrocytes in rhythmic behaviours? Prog Neurobiol 2021; 202:102052. [PMID: 33894330 DOI: 10.1016/j.pneurobio.2021.102052] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 03/03/2021] [Accepted: 04/13/2021] [Indexed: 01/16/2023]
Abstract
Astrocytes are a functionally diverse form of glial cell involved in various aspects of nervous system infrastructure, from the metabolic and structural support of neurons to direct neuromodulation of synaptic activity. Investigating how astrocytes behave in functionally related circuits may help us understand whether there is any conserved logic to the role of astrocytes within neuronal networks. Astrocytes are implicated as key neuromodulatory cells within neural circuits that control a number of rhythmic behaviours such as breathing, locomotion and circadian sleep-wake cycles. In this review, we examine the evidence that astrocytes are directly involved in the regulation of the neural circuits underlying six different rhythmic behaviours: locomotion, breathing, chewing, gastrointestinal motility, circadian sleep-wake cycles and oscillatory feeding behaviour. We discuss how astrocytes are integrated into the neuronal networks that regulate these behaviours, and identify the potential gliotransmission signalling mechanisms involved. From reviewing the evidence of astrocytic involvement in a range of rhythmic behaviours, we reveal a heterogenous array of gliotransmission mechanisms, which help to regulate neuronal networks. However, we also observe an intriguing thread of commonality, in the form of purinergic gliotransmission, which is frequently utilised to facilitate feedback inhibition within rhythmic networks to constrain a given behaviour within its operational range.
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Affiliation(s)
- Matthew J Broadhead
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, UK.
| | - Gareth B Miles
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, UK
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17
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Effects of Coffee and Its Components on the Gastrointestinal Tract and the Brain-Gut Axis. Nutrients 2020; 13:nu13010088. [PMID: 33383958 PMCID: PMC7824117 DOI: 10.3390/nu13010088] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 12/23/2020] [Accepted: 12/25/2020] [Indexed: 02/06/2023] Open
Abstract
Coffee is one of the most popular beverages consumed worldwide. Roasted coffee is a complex mixture of thousands of bioactive compounds, and some of them have numerous potential health-promoting properties that have been extensively studied in the cardiovascular and central nervous systems, with relatively much less attention given to other body systems, such as the gastrointestinal tract and its particular connection with the brain, known as the brain–gut axis. This narrative review provides an overview of the effect of coffee brew; its by-products; and its components on the gastrointestinal mucosa (mainly involved in permeability, secretion, and proliferation), the neural and non-neural components of the gut wall responsible for its motor function, and the brain–gut axis. Despite in vitro, in vivo, and epidemiological studies having shown that coffee may exert multiple effects on the digestive tract, including antioxidant, anti-inflammatory, and antiproliferative effects on the mucosa, and pro-motility effects on the external muscle layers, much is still surprisingly unknown. Further studies are needed to understand the mechanisms of action of certain health-promoting properties of coffee on the gastrointestinal tract and to transfer this knowledge to the industry to develop functional foods to improve the gastrointestinal and brain–gut axis health.
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18
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Enteric Glia at the Crossroads between Intestinal Immune System and Epithelial Barrier: Implications for Parkinson Disease. Int J Mol Sci 2020; 21:ijms21239199. [PMID: 33276665 PMCID: PMC7730281 DOI: 10.3390/ijms21239199] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 11/30/2020] [Accepted: 11/30/2020] [Indexed: 12/15/2022] Open
Abstract
Over recent years, several investigations have suggested that Parkinson’s disease (PD) can be regarded as the consequence of a bowel disorder. Indeed, gastrointestinal symptoms can occur at all stages of this neurodegenerative disease and in up to a third of cases, their onset can precede the involvement of the central nervous system. Recent data suggest that enteric glial cells (EGCs) may play a major role in PD-related gastrointestinal disturbances, as well as in the development and progression of the central disease. In addition to their trophic and structural functions, EGCs are crucial for the homeostatic control of a wide range of gastrointestinal activities. The main purpose of this review was to provide a detailed overview of the role of EGCs in intestinal PD-associated alterations, with particular regard for their participation in digestive and central inflammation as well as the dynamic interactions between glial cells and intestinal epithelial barrier. Accumulating evidence suggests that several pathological intestinal conditions, associated with an impairment of barrier permeability, may trigger dysfunctions of EGCs and their shift towards a proinflammatory phenotype. The reactive gliosis is likely responsible for PD-related neuroinflammation and the associated pathological changes in the ENS. Thus, ameliorating the efficiency of mucosal barrier, as well as avoiding IEB disruption and the related reactive gliosis, might theoretically prevent the onset of PD or, at least, counteract its progression.
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19
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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: 89] [Impact Index Per Article: 22.3] [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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20
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Drimousis S, Markus I, Murphy TV, Perera DS, Phan-Thien KC, Zhang L, Liu L. Gender-Related Differences of Tachykinin NK2Receptor Expression and Activity in Human Colonic Smooth Muscle. J Pharmacol Exp Ther 2020; 375:28-39. [DOI: 10.1124/jpet.120.265967] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 07/28/2020] [Indexed: 12/20/2022] Open
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21
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Broadhead MJ, Miles GB. Bi-Directional Communication Between Neurons and Astrocytes Modulates Spinal Motor Circuits. Front Cell Neurosci 2020; 14:30. [PMID: 32180706 PMCID: PMC7057799 DOI: 10.3389/fncel.2020.00030] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 02/03/2020] [Indexed: 01/22/2023] Open
Abstract
Evidence suggests that astrocytes are not merely supportive cells in the nervous system but may actively participate in the control of neural circuits underlying cognition and behavior. In this study, we examined the role of astrocytes within the motor circuitry of the mammalian spinal cord. Pharmacogenetic manipulation of astrocytic activity in isolated spinal cord preparations obtained from neonatal mice revealed astrocyte-derived, adenosinergic modulation of the frequency of rhythmic output generated by the locomotor central pattern generator (CPG) network. Live Ca2+ imaging demonstrated increased activity in astrocytes during locomotor-related output and in response to the direct stimulation of spinal neurons. Finally, astrocytes were found to respond to neuronally-derived glutamate in a metabotropic glutamate receptor 5 (mGluR5) dependent manner, which in turn drives astrocytic modulation of the locomotor network. Our work identifies bi-directional signaling mechanisms between neurons and astrocytes underlying modulatory feedback control of motor circuits, which may act to constrain network output within optimal ranges for movement.
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Affiliation(s)
- Matthew J Broadhead
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, United Kingdom
| | - Gareth B Miles
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, United Kingdom
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22
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Yeh KM, Johansson O, Le H, Rao K, Markus I, Perera DS, Lubowski DZ, King DW, Zhang L, Chen H, Liu L. Cystic fibrosis transmembrane conductance regulator modulates enteric cholinergic activities and is abnormally expressed in the enteric ganglia of patients with slow transit constipation. J Gastroenterol 2019; 54:994-1006. [PMID: 31392489 DOI: 10.1007/s00535-019-01610-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 07/31/2019] [Indexed: 02/04/2023]
Abstract
BACKGROUND Cystic fibrosis transmembrane conductance regulator (CFTR) was recently found in the enteric nervous system, where its role is unclear. We aimed to identify which enteric neuronal structures express CFTR, whether CFTR modulates enteric neurotransmission and if altered CFTR expression is associated with slow transit constipation (STC). METHODS Immunofluorescence double labeling was performed to localize CFTR with various neuronal and glial cell markers in the human colon. The immunoreactivity (IR) of CFTR and choline acetyltransferase (ChAT) on myenteric plexus of control and STC colon was quantitatively analyzed. In control colonic muscle strips, electrical field stimulation (EFS) evoked contractile responses and the release of acetylcholine (ACh) was measured in the presence of the CFTR channel inhibitor, CFTR(inh)-172. RESULTS CFTR-IR was densely localized to myenteric ganglia, where it was co-localized with neuronal markers HuC/D and β-tubulin, and glial marker S-100 but little with glial fibrillary acidic protein. Vesicular ACh transport was almost exclusively co-localized with CFTR, but neurons expressing nitric oxide synthase were CFTR negative. Significant reductions of CFTR-IR (P < 0.01) and ChAT-IR (P < 0.05) were observed on myenteric ganglia of STC compared to control. Pre-treatment of colonic muscle strips with CFTR(inh)-172 (10 µM) significantly inhibited EFS-evoked contractile responses (P < 0.01) and ACh release (P < 0.05). CONCLUSIONS Co-localization of CFTR-IR with cholinergic markers, inhibition of EFS-induced colonic muscle contractility and ACh release by CFTR(inh)-172 suggest that CFTR modulates enteric cholinergic neurotransmission. The downregulation of CFTR and ChAT in myenteric ganglia of STC correlated with the impaired contractile responses to EFS.
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Affiliation(s)
- Ka Ming Yeh
- Department of Pharmacology, Faculty of Medicine, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Olle Johansson
- Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden
| | - Huy Le
- Department of Pharmacology, Faculty of Medicine, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Karan Rao
- Department of Pharmacology, Faculty of Medicine, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Irit Markus
- Department of Pharmacology, Faculty of Medicine, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | | | | | | | - Li Zhang
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - Hongzhuan Chen
- School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Lu Liu
- Department of Pharmacology, Faculty of Medicine, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia.
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23
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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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24
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Kermarrec L, Durand T, Gonzales J, Pabois J, Hulin P, Neunlist M, Neveu I, Naveilhan P. Rat enteric glial cells express novel isoforms of Interleukine-7 regulated during inflammation. Neurogastroenterol Motil 2019; 31:e13467. [PMID: 30240048 DOI: 10.1111/nmo.13467] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 07/26/2018] [Accepted: 08/14/2018] [Indexed: 12/13/2022]
Abstract
BACKGROUND Neuroimmune interactions are essential to maintain gut homeostasis and prevent intestinal disorders but so far, the impact of enteric glial cells (EGC) on immune cells remains a relatively unexplored area of research. As a dysregulation of critical cytokines such as interleukine-7 (IL-7) was suggested to exacerbate gut chronic inflammation, we investigated whether EGC could be a source of IL-7 in the gastrointestinal tract. METHODS Expression of IL-7 in the rat enteric nervous system was analyzed by immunochemistry and Q-PCR. IL-7 variants were cloned and specific antibodies against rat IL-7 isoforms were raised to characterize their expression in the submucosal plexus. IL-7 isoforms were produced in vitro to analyze their impact on T-cell survival. KEY RESULTS Neurons and glial cells of the rat enteric nervous system expressed IL-7 at both mRNA and protein levels. Novel rat IL-7 isoforms with distinct C-terminal parts were detected. Three of these isoforms were found in EGC or in both enteric neurons and EGC. Exposure of EGC to pro-inflammatory cytokines (IL-1β and/or TNFα) induced an upregulation of all IL-7 isoforms. Interestingly, time-course and intensity of the upregulation varied according to the presence or absence of exon 5a in IL-7 variants. Functional analysis on T lymphocytes revealed that only canonical IL-7 protects T cells from cell death. CONCLUSIONS AND INFERENCES IL-7 and its variants are expressed by neurons and glial cells in the enteric nervous system. Their distinct expression and upregulation in inflammatory conditions suggest a role in gut homeostasis which could be critical in case of chronic inflammatory diseases.
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Affiliation(s)
- Laetitia Kermarrec
- Université de Nantes, INSERM, Institut des Maladies de l'Appareil Digestif, The enteric nervous system in gut and brain disorders, Nantes, France
| | - Tony Durand
- Université de Nantes, INSERM, Institut des Maladies de l'Appareil Digestif, The enteric nervous system in gut and brain disorders, Nantes, France
| | - Jacques Gonzales
- Université de Nantes, INSERM, Institut des Maladies de l'Appareil Digestif, The enteric nervous system in gut and brain disorders, Nantes, France
| | - Julie Pabois
- Université de Nantes, INSERM, Institut des Maladies de l'Appareil Digestif, The enteric nervous system in gut and brain disorders, Nantes, France
| | | | - Michel Neunlist
- Université de Nantes, INSERM, Institut des Maladies de l'Appareil Digestif, The enteric nervous system in gut and brain disorders, Nantes, France
| | - Isabelle Neveu
- Université de Nantes, INSERM, Institut des Maladies de l'Appareil Digestif, The enteric nervous system in gut and brain disorders, Nantes, France
| | - Philippe Naveilhan
- Université de Nantes, INSERM, Institut des Maladies de l'Appareil Digestif, The enteric nervous system in gut and brain disorders, Nantes, France
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25
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Delvalle NM, Fried DE, Rivera-Lopez G, Gaudette L, Gulbransen BD. Cholinergic activation of enteric glia is a physiological mechanism that contributes to the regulation of gastrointestinal motility. Am J Physiol Gastrointest Liver Physiol 2018; 315:G473-G483. [PMID: 29927320 PMCID: PMC6230698 DOI: 10.1152/ajpgi.00155.2018] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The reflexive activities of the gastrointestinal tract are regulated, in part, by precise interactions between neurons and glia in the enteric nervous system (ENS). Intraganglionic enteric glia are a unique type of peripheral glia that surround enteric neurons and regulate neuronal function, activity, and survival. Enteric glia express numerous neurotransmitter receptors that allow them to sense neuronal activity, but it is not clear if enteric glia monitor acetylcholine (ACh), the primary excitatory neurotransmitter in the ENS. Here, we tested the hypothesis that enteric glia detect ACh and that glial activation by ACh contributes to the physiological regulation of gut functions. Our results show that myenteric enteric glia express both the M3 and M5 subtypes of muscarinic receptors (MRs) and that muscarine drives intracellular calcium (Ca2+) signaling predominantly through M3R activation. To elucidate the functional effects of activation of glial M3Rs, we used GFAP::hM3Dq mice that express a modified human M3R (hM3Dq) exclusively on glial fibrillary acidic protein (GFAP) positive glia to directly activate glial hM3Dqs using clozapine- N-oxide. Using spatiotemporal mapping analysis, we found that the activation of glial hM3Dq receptors enhances motility reflexes ex vivo. Continuous stimulation of hM3Dq receptors in vivo, drove changes in gastrointestinal motility without affecting neuronal survival in the ENS and glial muscarinic receptor activation did not alter neuron survival in vitro. Our results provide the first evidence that GFAP intraganglionic enteric glia express functional muscarinic receptors and suggest that the activation of glial muscarinic receptors contributes to the physiological regulation of functions. NEW & NOTEWORTHY Enteric glia are emerging as novel regulators of enteric reflex circuits, but little is still known regarding the effects of specific transmitter pathways on glia and the resulting consequences on enteric reflexes. Here, we provide the first evidence that enteric glia monitor acetylcholine in the enteric nervous system and that glial activation by acetylcholine is a physiological mechanism that contributes to the functional regulation of intestinal reflexes.
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Affiliation(s)
| | - David E. Fried
- 2Department of Physiology, Michigan State University, East Lansing, Michigan
| | | | - Luke Gaudette
- 1Neuroscience Program, Michigan State University, East Lansing, Michigan
| | - Brian D. Gulbransen
- 1Neuroscience Program, Michigan State University, East Lansing, Michigan,2Department of Physiology, Michigan State University, East Lansing, Michigan
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Fujita M, Yagi T, Okura U, Tanaka J, Hirashima N, Tanaka M. Calcineurin B1 Deficiency in Glial Cells Induces Mucosal Degeneration and Inflammation in Mouse Small Intestine. Biol Pharm Bull 2018; 41:786-796. [DOI: 10.1248/bpb.b18-00041] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Maya Fujita
- Department of Cellular Biophysics, Graduate School of Pharmaceutical Sciences, Nagoya City University
| | - Takaki Yagi
- Department of Cellular Biophysics, Graduate School of Pharmaceutical Sciences, Nagoya City University
| | - Umi Okura
- Department of Cellular Biophysics, Graduate School of Pharmaceutical Sciences, Nagoya City University
| | - Jun’ichi Tanaka
- Department of Cellular Biophysics, Graduate School of Pharmaceutical Sciences, Nagoya City University
| | - Naohide Hirashima
- Department of Cellular Biophysics, Graduate School of Pharmaceutical Sciences, Nagoya City University
| | - Masahiko Tanaka
- Department of Cellular Biophysics, Graduate School of Pharmaceutical Sciences, Nagoya City University
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27
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Bassotti G, Macchioni L, Corazzi L, Marconi P, Fettucciari K. Clostridium difficile-related postinfectious IBS: a case of enteroglial microbiological stalking and/or the solution of a conundrum? Cell Mol Life Sci 2018; 75:1145-1149. [PMID: 29285574 PMCID: PMC11105427 DOI: 10.1007/s00018-017-2736-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 12/11/2017] [Accepted: 12/20/2017] [Indexed: 02/06/2023]
Abstract
Post-infectious irritable bowel syndrome is a well-defined pathological entity that develops in about one-third of subjects after an acute infection (bacterial, viral) or parasitic infestation. Only recently it has been documented that an high incidence of post-infectious irritable bowel syndrome occurs after Clostridium difficile infection. However, until now it is not known why in some patients recovered from this infection the gastrointestinal disturbances persist for months or years. Based on our in vitro studies on enteric glial cells exposed to the effects of C. difficile toxin B, we hypothesize that persistence of symptoms up to the development of irritable bowel syndrome might be due to a disturbance/impairment of the correct functions of the enteroglial intestinal network.
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Affiliation(s)
- Gabrio Bassotti
- Department of Medicine, University of Perugia Medical School, Perugia, Italy.
- Gastroenterology and Hepatology Section, Santa Maria della Misericordia Hospital, Piazzale Menghini, 1, 06156, San Sisto (Perugia), Italy.
| | - Lara Macchioni
- Department of Experimental Medicine, University of Perugia Medical School, Perugia, Italy
| | - Lanfranco Corazzi
- Department of Experimental Medicine, University of Perugia Medical School, Perugia, Italy
| | - Pierfrancesco Marconi
- Department of Experimental Medicine, University of Perugia Medical School, Perugia, Italy
| | - Katia Fettucciari
- Department of Experimental Medicine, University of Perugia Medical School, Perugia, Italy
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Grubišić V, Verkhratsky A, Zorec R, Parpura V. Enteric glia regulate gut motility in health and disease. Brain Res Bull 2018; 136:109-117. [PMID: 28363846 PMCID: PMC5620110 DOI: 10.1016/j.brainresbull.2017.03.011] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 02/20/2017] [Accepted: 03/28/2017] [Indexed: 12/16/2022]
Abstract
The enteric nervous system, often referred to as the second brain, is the largest assembly of neurons and glia outside the central nervous system. The enteric nervous system resides within the wall of the digestive tract and regulates local gut reflexes involved in gastrointestinal motility and fluid transport; these functions can be accomplished in the absence of the extrinsic innervation from the central nervous system. It is neurons and their circuitry within the enteric nervous system that govern the gut reflexes. However, it is becoming clear that enteric glial cells are also actively involved in this process through the bidirectional signaling with neurons and other cells in the gut wall. We synthesize the recently discovered modulatory roles of enteric gliotransmission in gut motility and provide our perspective for future lines of research.
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Affiliation(s)
- Vladimir Grubišić
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL, USA; Neuroscience Program, Department of Physiology, Michigan State University, 567 Wilson Road, East Lansing, MI, 48824, USA
| | - Alexei Verkhratsky
- The University of Manchester, Manchester, UK; Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology University of Ljubljana, Ljubljana, Slovenia; Celica BIOMEDICAL, Ljubljana, Slovenia
| | - Vladimir Parpura
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL, USA.
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Vieira C, Ferreirinha F, Magalhães-Cardoso MT, Silva I, Marques P, Correia-de-Sá P. Post-inflammatory Ileitis Induces Non-neuronal Purinergic Signaling Adjustments of Cholinergic Neurotransmission in the Myenteric Plexus. Front Pharmacol 2017; 8:811. [PMID: 29167643 PMCID: PMC5682326 DOI: 10.3389/fphar.2017.00811] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 10/26/2017] [Indexed: 12/11/2022] Open
Abstract
Uncoupling between ATP overflow and extracellular adenosine formation changes purinergic signaling in post-inflammatory ileitis. Adenosine neuromodulation deficits were ascribed to feed-forward inhibition of ecto-5′-nucleotidase/CD73 by high extracellular adenine nucleotides in the inflamed ileum. Here, we hypothesized that inflammation-induced changes in cellular density may also account to unbalance the release of purines and their influence on [3H]acetylcholine release from longitudinal muscle-myenteric plexus preparations of the ileum of 2,4,6-trinitrobenzenesulfonic acid (TNBS)-treated rats. The population of S100β-positive glial cells increase, whereas Ano-1-positive interstitial cells of Cajal (ICCs) diminished, in the ileum 7-days after the inflammatory insult. In the absence of changes in the density of VAChT-positive cholinergic nerves detected by immunofluorescence confocal microscopy, the inflamed myenteric plexus released smaller amounts of [3H]acetylcholine which also became less sensitive to neuronal blockade by tetrodotoxin (1 μM). Instead, [3H]acetylcholine release was attenuated by sodium fluoroacetate (5 mM), carbenoxolone (10 μM) and A438079 (3 μM), which prevent activation of glial cells, pannexin-1 hemichannels and P2X7 receptors, respectively. Sodium fluoroacetate also decreased ATP overflow without significantly affecting the extracellular adenosine levels, thus indicating that surplus ATP release parallels reactive gliosis in post-inflammatory ileitis. Conversely, loss of ICCs may explain the lower amounts of adenosine detected in TNBS-treated preparations, since blockade of Cav3 (T-type) channels existing in ICCs with mibefradil (3 μM) or inhibition of the equilibrative nucleoside transporter 1 with dipyridamole (0.5 μM), both decreased extracellular adenosine. Data indicate that post-inflammatory ileitis operates a shift on purinergic neuromodulation reflecting the upregulation of ATP-releasing enteric glial cells and the depletion of ICCs accounting for decreased adenosine overflow via equilibrative nucleoside transporters.
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Affiliation(s)
- Cátia Vieira
- Laboratório de Farmacologia e Neurobiologia, Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Fátima Ferreirinha
- Laboratório de Farmacologia e Neurobiologia, Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Maria T Magalhães-Cardoso
- Laboratório de Farmacologia e Neurobiologia, Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Isabel Silva
- Laboratório de Farmacologia e Neurobiologia, Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Patrícia Marques
- Laboratório de Farmacologia e Neurobiologia, Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Paulo Correia-de-Sá
- Laboratório de Farmacologia e Neurobiologia, Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal
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Grubišić V, Gulbransen BD. Enteric glial activity regulates secretomotor function in the mouse colon but does not acutely affect gut permeability. J Physiol 2017; 595:3409-3424. [PMID: 28066889 DOI: 10.1113/jp273492] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2016] [Accepted: 11/30/2016] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS The role of enteric glial cell activity in the acute regulation of epithelial barrier and secretomotor functions of the intestines under physiological conditions is not clear. We used transgenic mice to modify glial activity and found that enteric glia significantly contribute to the neurogenic ion transport while glial activity does not appear to play a major role in the acute regulation of barrier function. The selective activation of glial activity evoked electrogenic ion transport primarily through neural pathways and was sufficient to drive electrogenic ion transport to an extent equal to the direct activation of neurogenic ion transport. These findings provide novel insight into the cellular mechanisms that control fluid transport homeostasis in the intestine and might provide novel therapeutic avenues for functional diarrheal diseases. ABSTRACT Enteric glial cells are often implicated in the regulation of epithelial barrier and secretomotor functions of the intestines. But whether glial cell activity regulates these functions acutely under physiological conditions is not clear. We addressed this issue by using transgenic animal models to modify the activity of enteric glia, either reducing glial expression of connexin 43 in Sox10::CreERT2+/- /Cx43f/f mice or activating glial calcium responses in GFAP::hM3Dq mice, and tested the effects on colonic barrier function and electrogenic ion transport in Ussing chambers. We assessed neuronal-dependent and -independent contributions by activating or inhibiting neurogenic activity with veratridine and tetrodotoxin, respectively. Our results show that the reduction of glial Cx43 expression in Sox10::CreERT2+/- /Cx43f/f mice significantly reduced neurogenic ion transport. The selective glial activation in tissues from GFAP::hM3Dq mice evoked electrogenic ion transport to an extent equal to the direct activation of neurogenic ion transport with veratridine and glial driven responses consisted of both tetrodotoxin-sensitive and -insensitive components. The selective glial stimulation did not affect transmural ion conductance or cell-impermeant dye flux but the baseline ion conductance was more variable in Sox10::CreERT2+/- /Cx43f/f tissues. Together, our findings show that glial activity contributes to the regulation of electrogenic ion transport in the intestine through effects on neurons and possibly direct effects on epithelial cells. However, glial activity does not appear to play a major role in the acute regulation of barrier function. These findings provide novel insight into the cellular mechanisms that control fluid transport homeostasis in the intestine.
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Affiliation(s)
- Vladimir Grubišić
- Neuroscience Program, Department of Physiology, Michigan State University, 567 Wilson Road, East Lansing, MI, 48824, USA
| | - Brian D Gulbransen
- Neuroscience Program, Department of Physiology, Michigan State University, 567 Wilson Road, East Lansing, MI, 48824, USA
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Grubišić V, Parpura V. Two modes of enteric gliotransmission differentially affect gut physiology. Glia 2017; 65:699-711. [PMID: 28168732 DOI: 10.1002/glia.23121] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2016] [Revised: 01/07/2017] [Accepted: 01/10/2017] [Indexed: 11/08/2022]
Abstract
Enteric glia (EG) in the enteric nervous system can modulate neuronally regulated gut functions. Using molecular genetics, we assessed the effects that molecular entities expressed in EG and otherwise mediating two distinct mechanisms of gliotransmitter release, connexin 43 (Cx43) hemichannel vs. Ca2+ -dependent exocytosis, have on gut function. The expression of mutated Cx43G138R (which favors hemichannel, as opposed to gap-junctional activity) in EG increased gut motility in vivo, while a knock-down of Cx43 in EG resulted in the reduction of gut motility. However, inhibition of Ca2+ -dependent exocytosis in EG did not affect gut motility in vivo; rather, it increased the fecal pellet fluid content. Hampering either Cx43 expression or Ca2+ -dependent exocytosis in EG had an effect on colonic migrating motor complexes, mainly decreasing frequency and velocity of contractions ex vivo. Thus, EG can differentially modulate gut reflexes using the above two distinct mechanisms of gliotransmission.
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Affiliation(s)
- Vladimir Grubišić
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama.,Department of Physiology, Neuroscience Program, Michigan State University, East Lansing, Michigan
| | - Vladimir Parpura
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama
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Grubišić V, Gulbransen BD. Enteric glia: the most alimentary of all glia. J Physiol 2017; 595:557-570. [PMID: 27106597 PMCID: PMC5233670 DOI: 10.1113/jp271021] [Citation(s) in RCA: 123] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 01/06/2016] [Indexed: 12/12/2022] Open
Abstract
Glia (from Greek γλοία meaning 'glue') pertains to non-neuronal cells in the central (CNS) and peripheral nervous system (PNS) that nourish neurons and maintain homeostasis. In addition, glia are now increasingly appreciated as active regulators of numerous physiological processes initially considered exclusively under neuronal regulation. For instance, enteric glia, a collection of glial cells residing within the walls of the intestinal tract, regulate intestinal motility, a well-characterized reflex controlled by enteric neurons. Enteric glia also interact with various non-neuronal cell types in the gut wall such as enterocytes, enteroendocrine and immune cells and are therefore emerging as important local regulators of diverse gut functions. The intricate molecular mechanisms that govern glia-mediated regulation are beginning to be discovered, but much remains unknown about the functions of enteric glia in health and disease. Here we present a current view of the enteric glia and their regulatory roles in gastrointestinal (GI) (patho)physiology; from GI motility and epithelial barrier function to enteric neuroinflammation.
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Affiliation(s)
- Vladimir Grubišić
- Neuroscience Program, Department of PhysiologyMichigan State University567 Wilson RoadEast LansingMI48824USA
| | - Brian D. Gulbransen
- Neuroscience Program, Department of PhysiologyMichigan State University567 Wilson RoadEast LansingMI48824USA
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Smith TK, Koh SD. A model of the enteric neural circuitry underlying the generation of rhythmic motor patterns in the colon: the role of serotonin. Am J Physiol Gastrointest Liver Physiol 2017; 312:G1-G14. [PMID: 27789457 PMCID: PMC5283906 DOI: 10.1152/ajpgi.00337.2016] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 10/19/2016] [Indexed: 01/31/2023]
Abstract
We discuss the role of multiple cell types involved in rhythmic motor patterns in the large intestine that include tonic inhibition of the muscle layers interrupted by rhythmic colonic migrating motor complexes (CMMCs) and secretomotor activity. We propose a model that assumes these motor patterns are dependent on myenteric descending 5-hydroxytryptamine (5-HT, serotonin) interneurons. Asynchronous firing in 5-HT neurons excite inhibitory motor neurons (IMNs) to generate tonic inhibition occurring between CMMCs. IMNs release mainly nitric oxide (NO) to inhibit the muscle, intrinsic primary afferent neurons (IPANs), glial cells, and pacemaker myenteric pacemaker interstitial cells of Cajal (ICC-MY). Mucosal release of 5-HT from enterochromaffin (EC) cells excites the mucosal endings of IPANs that synapse with 5-HT descending interneurons and perhaps ascending interneurons, thereby coupling EC cell 5-HT to myenteric 5-HT neurons, synchronizing their activity. Synchronized 5-HT neurons generate a slow excitatory postsynaptic potential in IPANs via 5-HT7 receptors and excite glial cells and ascending excitatory nerve pathways that are normally inhibited by NO. Excited glial cells release prostaglandins to inhibit IMNs (disinhibition) to allow full excitation of ICC-MY and muscle by excitatory motor neurons (EMNs). EMNs release ACh and tachykinins to excite pacemaker ICC-MY and muscle, leading to the simultaneous contraction of both the longitudinal and circular muscle layers. Myenteric 5-HT neurons also project to the submucous plexus to couple motility with secretion, especially during a CMMC. Glial cells are necessary for switching between different colonic motor behaviors. This model emphasizes the importance of myenteric 5-HT neurons and the likely consequence of their coupling and uncoupling to mucosal 5-HT by IPANs during colonic motor behaviors.
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Affiliation(s)
- Terence Keith Smith
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Sang Don Koh
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
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McClain JL, Gulbransen BD. The acute inhibition of enteric glial metabolism with fluoroacetate alters calcium signaling, hemichannel function, and the expression of key proteins. J Neurophysiol 2016; 117:365-375. [PMID: 27784805 DOI: 10.1152/jn.00507.2016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 10/25/2016] [Indexed: 11/22/2022] Open
Abstract
Glia play key roles in the regulation of neurotransmission in the nervous system. Fluoroacetate (FA) is a metabolic poison widely used to study glial functions by disrupting the tricarboxylic acid cycle enzyme aconitase. Despite the widespread use of FA, the effects of FA on essential glial functions such as calcium (Ca2+) signaling and hemichannel function remain unknown. Therefore, our goal was to assess specifically the impact of FA on essential glial cell functions that are involved with neurotransmission in the enteric nervous system. To this end, we generated a new optogenetic mouse model to study specifically the effects of FA on enteric glial Ca2+ signaling by crossing PC::G5-tdTomato mice with Sox10::creERT2 mice. FA did not change the peak glial Ca2+ response when averaged across all glia within a ganglion. However, FA decreased the percent of responding glia by 30% (P < 0.05) and increased the peak Ca2+ response of the glial cells that still exhibited a response by 26% (P < 0.01). Disruption of Ca2+ signaling with FA impaired the activity-dependent uptake of ethidium bromide through connexin-43 (Cx43) hemichannels (P < 0.05) but did not affect baseline Cx43-dependent dye uptake. FA did not cause overt glial or neurodegeneration, but glial cells significantly increased glial fibrillary acid protein by 56% (P < 0.05) following treatment with FA. Together, these data show that the acute impairment of glial metabolism with FA causes key changes in glial functions associated with their roles in neurotransmission and phenotypic changes indicative of reactive gliosis. NEW & NOTEWORTHY Our study shows that the acute impairment of enteric glial metabolism with fluoroacetate (FA) alters specific glial functions that are associated with the modification of neurotransmission in the gut. These include subtle changes to glial agonist-evoked calcium signaling, the subsequent disruption of connexin-43 hemichannels, and changes in protein expression that are consistent with a transition to reactive glia. These changes in glial function offer a mechanistic explanation for the effects of FA on peripheral neuronal networks.
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Affiliation(s)
- Jonathon L McClain
- Department of Physiology, Michigan State University, East Lansing, Michigan; and
| | - Brian D Gulbransen
- Department of Physiology, Michigan State University, East Lansing, Michigan; and .,Neuroscience Program, Michigan State University, East Lansing, Michigan
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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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BDNF contributes to IBS-like colonic hypersensitivity via activating the enteroglia-nerve unit. Sci Rep 2016; 6:20320. [PMID: 26837784 PMCID: PMC4738267 DOI: 10.1038/srep20320] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 12/30/2015] [Indexed: 02/08/2023] Open
Abstract
The over-expressed colonic brain-derived neurotrophic factor (BDNF) has been reported to be associated with abdominal pain in patients with irritable bowel syndrome (IBS). However, the neuropathological mechanism is unclear. We here investigated the involvement of enteroglial cells (EGCs) and enteric nerves in IBS-like visceral hypersensitivity. We showed that glial fibrillary acidic protein (GFAP), tyrosine receptor kinase B (TrkB) and substance P (SP) were significantly increased in the colonic mucosa of IBS patients. The upregulation of those proteins was also observed in the colon of mice with visceral hypersensitivity, but not in the colon of BDNF(+/-) mice. Functionally, TrkB or EGC inhibitors, or BDNF knockdown significantly suppressed visceral hypersensitivity in mice. Using the EGC cell line, we found that recombinant human BDNF (r-HuBDNF) could directly activate EGCs via the TrkB-phospholipase Cγ1 pathway, thereby inducing a significant upregulation of SP. Moreover, supernatants from r-HuBDNF-activated EGC culture medium, rather than r-HuBDNF alone, triggered markedly augmented discharges in isolated intestinal mesenteric afferent nerves. r-HuBDNF alone could cause mesenteric afferent mechanical hypersensitivity independently, and this effect was synergistically enhanced by activated EGCs. We conclude that EGC-enteric nerve unit may be involved in IBS-like visceral hypersensitivity, and this process is likely initiated by BDNF-TrkB pathway activation.
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Ochoa-Cortes F, Turco F, Linan-Rico A, Soghomonyan S, Whitaker E, Wehner S, Cuomo R, Christofi FL. Enteric Glial Cells: A New Frontier in Neurogastroenterology and Clinical Target for Inflammatory Bowel Diseases. Inflamm Bowel Dis 2016; 22:433-49. [PMID: 26689598 PMCID: PMC4718179 DOI: 10.1097/mib.0000000000000667] [Citation(s) in RCA: 110] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 08/29/2015] [Indexed: 12/12/2022]
Abstract
The word "glia" is derived from the Greek word "γλoια," glue of the enteric nervous system, and for many years, enteric glial cells (EGCs) were believed to provide mainly structural support. However, EGCs as astrocytes in the central nervous system may serve a much more vital and active role in the enteric nervous system, and in homeostatic regulation of gastrointestinal functions. The emphasis of this review will be on emerging concepts supported by basic, translational, and/or clinical studies, implicating EGCs in neuron-to-glial (neuroglial) communication, motility, interactions with other cells in the gut microenvironment, infection, and inflammatory bowel diseases. The concept of the "reactive glial phenotype" is explored as it relates to inflammatory bowel diseases, bacterial and viral infections, postoperative ileus, functional gastrointestinal disorders, and motility disorders. The main theme of this review is that EGCs are emerging as a new frontier in neurogastroenterology and a potential therapeutic target. New technological innovations in neuroimaging techniques are facilitating progress in the field, and an update is provided on exciting new translational studies. Gaps in our knowledge are discussed for further research. Restoring normal EGC function may prove to be an efficient strategy to dampen inflammation. Probiotics, palmitoylethanolamide (peroxisome proliferator-activated receptor-α), interleukin-1 antagonists (anakinra), and interventions acting on nitric oxide, receptor for advanced glycation end products, S100B, or purinergic signaling pathways are relevant clinical targets on EGCs with therapeutic potential.
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Affiliation(s)
| | - Fabio Turco
- Department of Anesthesiology, The Ohio State University, Columbus, Ohio
- Department of Clinical and Experimental Medicine, Gastroenterological Unit, “Federico II” University of Naples, Naples, Italy; and
| | | | - Suren Soghomonyan
- Department of Anesthesiology, The Ohio State University, Columbus, Ohio
| | - Emmett Whitaker
- Department of Anesthesiology, The Ohio State University, Columbus, Ohio
| | - Sven Wehner
- Department of Surgery, University of Bonn, Bonn, Germany
| | - Rosario Cuomo
- Department of Clinical and Experimental Medicine, Gastroenterological Unit, “Federico II” University of Naples, Naples, Italy; and
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Hennig GW, Gould TW, Koh SD, Corrigan RD, Heredia DJ, Shonnard MC, Smith TK. Use of Genetically Encoded Calcium Indicators (GECIs) Combined with Advanced Motion Tracking Techniques to Examine the Behavior of Neurons and Glia in the Enteric Nervous System of the Intact Murine Colon. Front Cell Neurosci 2015; 9:436. [PMID: 26617487 PMCID: PMC4639702 DOI: 10.3389/fncel.2015.00436] [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: 09/08/2015] [Accepted: 10/16/2015] [Indexed: 12/19/2022] Open
Abstract
Genetically encoded Ca2+ indicators (GECIs) have been used extensively in many body systems to detect Ca2+ transients associated with neuronal activity. Their adoption in enteric neurobiology has been slower, although they offer many advantages in terms of selectivity, signal-to-noise and non-invasiveness. Our aims were to utilize a number of cell-specific promoters to express the Ca2+ indicator GCaMP3 in different classes of neurons and glia to determine their effectiveness in measuring activity in enteric neural networks during colonic motor behaviors. We bred several GCaMP3 mice: (1) Wnt1-GCaMP3, all enteric neurons and glia; (2) GFAP-GCaMP3, enteric glia; (3) nNOS-GaMP3, enteric nitrergic neurons; and (4) ChAT-GCaMP3, enteric cholinergic neurons. These mice allowed us to study the behavior of the enteric neurons in the intact colon maintained at a physiological temperature, especially during the colonic migrating motor complex (CMMC), using low power Ca2+ imaging. In this preliminary study, we observed neuronal and glial cell Ca2+ transients in specific cells in both the myenteric and submucous plexus in all of the transgenic mice variants. The number of cells that could be simultaneously imaged at low power (100–1000 active cells) through the undissected gut required advanced motion tracking and analysis routines. The pattern of Ca2+ transients in myenteric neurons showed significant differences in response to spontaneous, oral or anal stimulation. Brief anal elongation or mucosal stimulation, which evokes a CMMC, were the most effective stimuli and elicited a powerful synchronized and prolonged burst of Ca2+ transients in many myenteric neurons, especially when compared with the same neurons during a spontaneous CMMC. In contrast, oral elongation, which normally inhibits CMMCs, appeared to suppress Ca2+ transients in some of the neurons active during a spontaneous or an anally evoked CMMC. The activity in glial networks appeared to follow neural activity but continued long after neural activity had waned. With these new tools an unprecedented level of detail can be recorded from the enteric nervous system (ENS) with minimal manipulation of tissue. These techniques can be extended in order to better understand the roles of particular enteric neurons and glia during normal and disordered motility.
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Affiliation(s)
- Grant W Hennig
- Department of Physiology and Cell Biology, University of Nevada School of Medicine Reno, NV, USA
| | - Thomas W Gould
- Department of Physiology and Cell Biology, University of Nevada School of Medicine Reno, NV, USA
| | - Sang Don Koh
- Department of Physiology and Cell Biology, University of Nevada School of Medicine Reno, NV, USA
| | - Robert D Corrigan
- Department of Physiology and Cell Biology, University of Nevada School of Medicine Reno, NV, USA
| | - Dante J Heredia
- Department of Physiology and Cell Biology, University of Nevada School of Medicine Reno, NV, USA
| | - Matthew C Shonnard
- Department of Physiology and Cell Biology, University of Nevada School of Medicine Reno, NV, USA
| | - Terence K Smith
- Department of Physiology and Cell Biology, University of Nevada School of Medicine Reno, NV, USA
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McClain JL, Fried DE, Gulbransen BD. Agonist-evoked Ca 2+ signaling in enteric glia drives neural programs that regulate intestinal motility in mice. Cell Mol Gastroenterol Hepatol 2015; 1:631-645. [PMID: 26693173 PMCID: PMC4673674 DOI: 10.1016/j.jcmgh.2015.08.004] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 08/14/2015] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS Gastrointestinal motility is regulated by enteric neural circuitry that includes enteric neurons and glia. Enteric glia monitor synaptic activity and exhibit responses to neurotransmitters that are encoded by intracellular calcium (Ca2+) signaling. What role evoked glial responses play in the neural regulation of gut motility is unknown. We tested how evoking Ca2+ signaling in enteric glia affects the neural control of intestinal motility. METHODS We used a novel chemogenetic mouse model that expresses the designer receptor hM3Dq under the transcriptional control of the glial fibrillary acidic protein (GFAP) promoter (GFAP::hM3Dq mice) to selectively trigger glial Ca2+ signaling. We used in situ Ca2+ imaging and immunohistochemistry to validate this model and assessed gut motility by measuring pellet output and composition, colonic bead expulsion time, small intestinal transit time, total gut transit time, colonic migrating motor complex (CMMC) recordings and muscle tension recordings. RESULTS hM3Dq receptor expression is confined to GFAP-positive enteric glia in the intestines of GFAP::hM3Dq mice. In these mice, application of the hM3Dq agonist clozapine-N-oxide (CNO) selectively triggers intracellular Ca2+ responses in enteric glia. Glial activation drove neurogenic contractions in the ileum and colon but had no effect on neurogenic relaxations. CNO enhanced the amplitude and frequency of CMMCs in ex vivo preparations of the colon and CNO increased colonic motility in vivo. CNO had no effect on the composition of fecal matter, small intestinal transit or whole gut transit. CONCLUSIONS Glial excitability encoded by intracellular Ca2+ signaling functions to modulate excitatory enteric circuits. Selectively triggering glial Ca2+ signaling might be a novel strategy to improve gut function in motility disorders.
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Affiliation(s)
| | - David E. Fried
- Department of Physiology, Michigan State University, East Lansing, Michigan
| | - Brian D. Gulbransen
- Department of Physiology, Michigan State University, East Lansing, Michigan
- Neuroscience Program, Michigan State University, East Lansing, Michigan
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Grubišić V, Parpura V. The second brain in autism spectrum disorder: could connexin 43 expressed in enteric glial cells play a role? Front Cell Neurosci 2015; 9:242. [PMID: 26190971 PMCID: PMC4490256 DOI: 10.3389/fncel.2015.00242] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 06/15/2015] [Indexed: 12/28/2022] Open
Affiliation(s)
- Vladimir Grubišić
- Department of Neurobiology, University of Alabama at Birmingham Birmingham, AL, USA ; Neuroscience Program, Department of Physiology, Michigan State University East Lansing, MI, USA
| | - Vladimir Parpura
- Department of Neurobiology, University of Alabama at Birmingham Birmingham, AL, USA
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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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Coelho-Aguiar JDM, Bon-Frauches AC, Gomes ALT, Veríssimo CP, Aguiar DP, Matias D, Thomasi BBDM, Gomes AS, Brito GADC, Moura-Neto V. The enteric glia: identity and functions. Glia 2015; 63:921-35. [PMID: 25703790 DOI: 10.1002/glia.22795] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 01/07/2015] [Indexed: 01/04/2023]
Abstract
Enteric glial cells were first described at the end of the 19th century, but they attracted more interest from researchers only in the last decades of the 20th. Although, they have a different embryological origin, the enteric GLIA share many characteristics with astrocytes, the main glial cell type of the central nervous system (CNS), such as in their expression of the same markers and in their functions. Here we review the construction of the enteric nervous system (ENS), with a focus on enteric glia, and also the main studies that have revealed the action of enteric glia in different aspects of gastrointestinal tract homeostasis, such as in the intestinal barrier, in communications with neurons, and in their action as progenitor cells. We also discuss recent discoveries about the roles of enteric glia in different disorders that affect the ENS, such as degenerative pathologies including Parkinson's and prion diseases, and in cases of intestinal diseases and injury.
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Affiliation(s)
- Juliana de Mattos Coelho-Aguiar
- Instituto Estadual do Cérebro Paulo Niemeyer, Secretaria de Estado de Saúde do Rio de Janeiro - SES/RJ, Rio de Janeiro, Brazil; Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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43
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Abstract
Reflex behaviors of the intestine are controlled by the enteric nervous system (ENS). The ENS is an integrative network of neurons and glia in two ganglionated plexuses housed in the gut wall. Enteric neurons and enteric glia are the only cell types within the enteric ganglia. The activity of enteric neurons and glia is responsible for coordinating intestinal functions. This protocol describes methods for observing the activity of neurons and glia within the intact ENS by imaging intracellular calcium (Ca(2+)) transients with fluorescent indicator dyes. Our technical discussion focuses on methods for Ca(2+) imaging in whole-mount preparations of the myenteric plexus from the rodent bowel. Bulk loading of ENS whole-mounts with a high-affinity Ca(2+) indicator such as Fluo-4 permits measurements of Ca(2+) responses in individual neurons or glial cells. These responses can be evoked repeatedly and reliably, which permits quantitative studies using pharmacological tools. Ca(2+) responses in cells of the ENS are recorded using a fluorescence microscope equipped with a cooled charge-coupled device (CCD) camera. Fluorescence measurements obtained using Ca(2+) imaging in whole-mount preparations offer a straightforward means of characterizing the mechanisms and potential functional consequences of Ca(2+) responses in enteric neurons and glial cells.
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44
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Neunlist M, Rolli-Derkinderen M, Latorre R, Van Landeghem L, Coron E, Derkinderen P, De Giorgio R. Enteric glial cells: recent developments and future directions. Gastroenterology 2014; 147:1230-7. [PMID: 25305504 DOI: 10.1053/j.gastro.2014.09.040] [Citation(s) in RCA: 122] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 09/11/2014] [Accepted: 09/12/2014] [Indexed: 12/12/2022]
Abstract
Since their discovery at the end of the 19th century, enteric glial cells (EGCs), the major cellular component of the enteric nervous system, have long been considered mere supportive cells for neurons. However, recent evidence has challenged this view and highlighted their central role in the regulation of gut homeostasis as well as their implication in digestive and extradigestive diseases. In this review, we summarize emerging concepts as to how EGCs regulate neuromediator expression, exert neuroprotective roles, and even act as neuronal as well as glial progenitors in the enteric nervous system. A particularly crucial property of EGCs is their ability to maintain the integrity of the intestinal epithelial barrier, a role that may have important clinical implications not only for digestive diseases, such as postoperative ileus and inflammatory bowel diseases, but also for extradigestive diseases, such as Parkinson disease or obesity. EGCs could also contribute directly to disease processes (eg, inflammation) by their ability to secrete chemokines/cytokines in response to bacterial or inflammatory challenges. Defining the pleiotropic roles exerted by EGCs may reveal better knowledge and help develop new targeted therapeutic options for a variety of gastrointestinal diseases.
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Affiliation(s)
- Michel Neunlist
- INSERM Unité 913, Nantes, France; Université Nantes, Nantes, France; CHU Nantes, Hôtel Dieu, Institut des Maladies de l'Appareil Digestif, Nantes, France.
| | - Malvyne Rolli-Derkinderen
- INSERM Unité 913, Nantes, France; Université Nantes, Nantes, France; CHU Nantes, Hôtel Dieu, Institut des Maladies de l'Appareil Digestif, Nantes, France
| | - Rocco Latorre
- Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy
| | - Laurianne Van Landeghem
- INSERM Unité 913, Nantes, France; Université Nantes, Nantes, France; CHU Nantes, Hôtel Dieu, Institut des Maladies de l'Appareil Digestif, Nantes, France
| | - Emmanuel Coron
- INSERM Unité 913, Nantes, France; Université Nantes, Nantes, France; CHU Nantes, Hôtel Dieu, Institut des Maladies de l'Appareil Digestif, Nantes, France
| | - Pascal Derkinderen
- INSERM Unité 913, Nantes, France; Université Nantes, Nantes, France; CHU Nantes, Hôtel Dieu, Institut des Maladies de l'Appareil Digestif, Nantes, France; Department of Neurology, CHU Nantes, Nantes, France
| | - Roberto De Giorgio
- Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy
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45
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Smith TK, Park KJ, Hennig GW. Colonic migrating motor complexes, high amplitude propagating contractions, neural reflexes and the importance of neuronal and mucosal serotonin. J Neurogastroenterol Motil 2014; 20:423-46. [PMID: 25273115 PMCID: PMC4204412 DOI: 10.5056/jnm14092] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 09/05/2014] [Accepted: 09/08/2014] [Indexed: 12/15/2022] Open
Abstract
The colonic migrating motor complex (CMMC) is a critical neurally mediated rhythmic propulsive contraction observed in the large intestine of many mammals. It seems to be equivalent to the high amplitude propagating contractions (HAPCs) in humans. This review focuses on the probable neural mechanisms involved in producing the CMMC or HAPC, their likely dependence on mucosal and neuronal serotonin and pacemaker insterstitial cells of Cajal networks and how intrinsic neural reflexes affect them. Discussed is the possibility that myenteric 5-hydroxytryptamine (5-HT) neurons are not only involved in tonic inhibition of the colon, but are also involved in generating the CMMC and modulation of the entire enteric nervous system, including coupling motility to secretion and blood flow. Mucosal 5-HT appears to be important for the initiation and effective propagation of CMMCs, although this mechanism is a longstanding controversy since the 1950s, which we will address. We argue that the slow apparent propagation of the CMMC/HAPC down the colon is unlikely to result from a slowly conducting wave front of neural activity, but more likely because of an interaction between ascending excitatory and descending (serotonergic) inhibitory neural pathways interacting both within the myenteric plexus and at the level of the muscle. That is, CMMC/HAPC propagation appears to be similar to esophageal peristalsis. The suppression of inhibitory (neuronal nitric oxide synthase) motor neurons and mucosal 5-HT release by an upregulation of prostaglandins has important implications in a number of gastrointestinal disorders, especially slow transit constipation.
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Affiliation(s)
- Terence K Smith
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Kyu Joo Park
- Department of Surgery, School of Medicine, Seoul National University, Seoul Korea
| | - Grant W Hennig
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, USA
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Boesmans W, Lasrado R, Vanden Berghe P, Pachnis V. Heterogeneity and phenotypic plasticity of glial cells in the mammalian enteric nervous system. Glia 2014; 63:229-41. [PMID: 25161129 DOI: 10.1002/glia.22746] [Citation(s) in RCA: 171] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 08/05/2014] [Indexed: 12/24/2022]
Abstract
Enteric glial cells are vital for the autonomic control of gastrointestinal homeostasis by the enteric nervous system. Several different functions have been assigned to enteric glial cells but whether these are performed by specialized subtypes with a distinctive phenotype and function remains elusive. We used Mosaic Analysis with Double Markers and inducible lineage tracing to characterize the morphology and dynamic molecular marker expression of enteric GLIA in the myenteric plexus. Functional analysis in individually identified enteric glia was performed by Ca(2+) imaging. Our experiments have identified four morphologically distinct subpopulations of enteric glia in the gastrointestinal tract of adult mice. Marker expression analysis showed that the majority of glia in the myenteric plexus co-express glial fibrillary acidic protein (GFAP), S100β, and Sox10. However, a considerable fraction (up to 80%) of glia outside the myenteric ganglia, did not label for these markers. Lineage tracing experiments suggest that these alternative combinations of markers reflect dynamic gene regulation rather than lineage restrictions. At the functional level, the three myenteric glia subtypes can be distinguished by their differential response to adenosine triphosphate. Together, our studies reveal extensive heterogeneity and phenotypic plasticity of enteric glial cells and set a framework for further investigations aimed at deciphering their role in digestive function and disease.
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Affiliation(s)
- Werend Boesmans
- Laboratory for Enteric NeuroScience (LENS), TARGID, Department of Clinical and Experimental Medicine, University of Leuven, Leuven, Belgium
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Yang W, Wang N, Shi X, Chen J. Synchronized dual pulse gastric electrical stimulation induces activation of enteric glial cells in rats with diabetic gastroparesis. Gastroenterol Res Pract 2014; 2014:964071. [PMID: 24860604 PMCID: PMC4003764 DOI: 10.1155/2014/964071] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 03/09/2014] [Accepted: 03/10/2014] [Indexed: 12/23/2022] Open
Abstract
Objective. The aims of this study were to investigate the effects of synchronized dual pulse gastric electrical stimulation (SGES) on gastric motility in different periods for diabetic rats and try to explore the possible mechanisms of the effects. Methods. Forty-six rats were used in the study. Gastric slow waves were recorded at baseline, 7-14-day diabetes and 56-63-day diabetes before and after stimulation and the age-matched control groups. SGES-60 mins and SGES-7 days (60 mins/day) were performed to test the effects on gastric motility and to evaluate glial marker S100B expression in stomach. Results. (1) Gastric emptying was accelerated in 7-14-day diabetes and delayed in 56-63-day diabetes. (2) The S100B expression in 56-63-day diabetes decreased and the ultrastructure changed. (3) The age-associated loss of EGC was observed in 56-63-day control group. (4) SGES was able to not only accelerate gastric emptying but also normalize gastric slow waves. (5) The S100B expression increased after SGES and the ultrastructure of EGC was partially restored. The effect of SGES-7 days was superior to SGES-60 mins. Conclusions. Delayed gastric emptying due to the growth of age may be related to the EGC inactivation. The effects of the SGES on gastric motility may be associated with EGC activation.
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Affiliation(s)
- Wei Yang
- Department of Gastroenterology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Nian Wang
- Department of Gastroenterology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Xue Shi
- Department of Gastroenterology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Jie Chen
- Department of Gastroenterology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
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Okamoto T, Barton MJ, Hennig GW, Birch GC, Grainger N, Corrigan RD, Koh SD, Sanders KM, Smith TK. Extensive projections of myenteric serotonergic neurons suggest they comprise the central processing unit in the colon. Neurogastroenterol Motil 2014; 26:556-70. [PMID: 24460867 DOI: 10.1111/nmo.12302] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 12/12/2013] [Indexed: 01/02/2023]
Abstract
BACKGROUND 5-Hydroxytryptamine (5-HT, serotonin) is an important regulator of colonic motility and secretion; yet the role of serotonergic neurons in the colon is controversial. METHODS We used immunohistochemical techniques to examine their projections throughout the enteric nervous system and interstitial cells of Cajal (ICC) networks in the murine proximal to mid colon. KEY RESULTS Serotonergic neurons, which were mainly calbindin positive, occurred only in myenteric ganglia (1 per 3 ganglia). They were larger than nNOS neurons but similar in size to Dogiel Type II (AH) neurons. 5-HT neurons, appeared to make numerous varicose contacts with each other, most nNOS neurons, Dogiel Type II/AH neurons and glial cells. 5-HT, calbindin and nNOS nerve fibers also formed a thin perimuscular nerve plexus that was associated with ganglia, which contained both nNOS positive and negative neurons, which lay directly upon the submucosal pacemaker ICC network. Neurons in perimuscular ganglia were surrounded by 5-HT varicosities. Submucous ganglia contained nNOS positive and negative neurons, and calbindin positive neurons, which also appeared richly supplied by serotonergic nerve varicosities. Serotonergic nerve fibers ran along submucosal arterioles, but not veins. Varicosities of serotonergic nerve fibers were closely associated with pacemaker ICC networks and with intramuscular ICC (ICC-IM). 5-HT2B receptors were found on a subpopulation of non-5-HT containing myenteric neurons and their varicosities, pacemaker ICC-MY and ICC-IM. CONCLUSIONS & INFERENCES Myenteric serotonergic neurons, whose axons exhibit considerable divergence, regulate the entire enteric nervous system and are important in coordinating motility with secretion. They are not just interneurons, as regularly assumed, but possibly also motor neurons to ICC and blood vessels, and some may even be sensory neurons.
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Affiliation(s)
- T Okamoto
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
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49
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McClain J, Grubišić V, Fried D, Gomez-Suarez RA, Leinninger GM, Sévigny J, Parpura V, Gulbransen BD. Ca2+ responses in enteric glia are mediated by connexin-43 hemichannels and modulate colonic transit in mice. Gastroenterology 2014; 146:497-507.e1. [PMID: 24211490 PMCID: PMC3935238 DOI: 10.1053/j.gastro.2013.10.061] [Citation(s) in RCA: 148] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 10/18/2013] [Accepted: 10/30/2013] [Indexed: 12/17/2022]
Abstract
BACKGROUND & AIMS In the enteric nervous system, neurotransmitters initiate changes in calcium (Ca(2+) responses) in glia, but it is not clear how this process affects intestinal function. We investigated whether Ca(2+)-mediated responses in enteric glia are required to maintain gastrointestinal function. METHODS We used in situ Ca(2+) imaging to monitor glial Ca(2+) responses, which were manipulated with pharmacologic agents or via glia-specific disruption of the gene encoding connexin-43 (Cx43) (hGFAP::CreER(T2+/-)/Cx43(f/f) mice). Gastrointestinal function was assessed based on pellet output, total gut transit, colonic bead expulsion, and muscle tension recordings. Proteins were localized and quantified by immunohistochemistry, immunoblot, and reverse transcription polymerase chain reaction analyses. RESULTS Ca(2+) responses in enteric glia of mice were mediated by Cx43 hemichannels. Cx43 immunoreactivity was confined to enteric glia within the myenteric plexus of the mouse colon; the Cx43 inhibitors carbenoxolone and 43Gap26 inhibited the ability of enteric glia to propagate Ca(2+) responses. In vivo attenuation of Ca(2+) responses in the enteric glial network slowed gut transit overall and delayed colonic transit--these changes are also observed during normal aging. Altered motility with increasing age was associated with reduced glial Ca(2+)-mediated responses and changes in glial expression of Cx43 messenger RNA and protein. CONCLUSIONS Ca(2+)-mediated responses in enteric glia regulate gastrointestinal function in mice. Altered intercellular signaling between enteric glia and neurons might contribute to motility disorders.
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Affiliation(s)
- Jonathon McClain
- Neuroscience Program and Department of Physiology, Michigan State University, 567 Wilson Road, East Lansing, MI, 48824 USA
| | - Vladimir Grubišić
- Department of Neurobiology, Center for Glial Biology in Medicine, Atomic Force Microscopy and Nanotechnology Laboratories, Civitan International Research Center, Evelyn F. McKnight Brain Institute, University of Alabama, Birmingham, AL 35294, USA
| | - David Fried
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824
| | - Roberto A Gomez-Suarez
- Department of Neurobiology, Center for Glial Biology in Medicine, Atomic Force Microscopy and Nanotechnology Laboratories, Civitan International Research Center, Evelyn F. McKnight Brain Institute, University of Alabama, Birmingham, AL 35294, USA.,Department of Pediatrics Division of Pediatric Gastroenterology Hepatology And Nutrition at Nemours Chlidren's Hospital. Orlando, FL 32827, USA
| | - Gina M Leinninger
- Neuroscience Program and Department of Physiology, Michigan State University, 567 Wilson Road, East Lansing, MI, 48824 USA
| | - Jean Sévigny
- Département de microbiologie-infectiologie et d'immunologie, Faculté de Médecine, Université Laval, Québec, QC, Canada.,Centre de recherche du CHU de Québec, Québec, QC, G1V 4G2 Canada
| | - Vladimir Parpura
- Department of Neurobiology, Center for Glial Biology in Medicine, Atomic Force Microscopy and Nanotechnology Laboratories, Civitan International Research Center, Evelyn F. McKnight Brain Institute, University of Alabama, Birmingham, AL 35294, USA.,Department of Biotechnology, University of Rijeka, 51000 Rijeka, Croatia
| | - Brian D Gulbransen
- Neuroscience Program and Department of Physiology, Michigan State University, 567 Wilson Road, East Lansing, MI, 48824 USA
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50
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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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