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Mayr S, Elfers K, Mazzuoli-Weber G. The recruitment of mechanosensitive enteric neurons in the guinea pig gastric fundus is dependent on ganglionic stretch level. Neurogastroenterol Motil 2024:e14858. [PMID: 38946168 DOI: 10.1111/nmo.14858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 05/23/2024] [Accepted: 06/20/2024] [Indexed: 07/02/2024]
Abstract
BACKGROUND Serving as a reservoir, the gastric fundus can expand significantly, with an initial receptive and a following adaptive relaxation, controlled by extrinsic and intrinsic reflex circuits, respectively. We hypothesize that mechanosensitive enteric neurons (MEN) are involved in the adaptive relaxation, which is initiated when a particular gastric volume and a certain stretch of the stomach wall is reached. To investigate whether the responsiveness of MEN in the gastric fundus is dependent on tissue stretch, we performed mechanical stimulations in stretched versus ganglia "at rest". METHODS Responses of myenteric neurons in the guinea pig gastric fundus were recorded with membrane potential imaging using Di-8-ANEPPS. MEN were identified by small-volume intraganglionic injection in ganglia stretched to different degrees using a self-constructed stretching tool. Immunohistochemical staining identified the neurochemical phenotype of MEN. Hexamethonium and capsaicin were added to test their effect on recruited MEN. KEY RESULTS In stretched compared to "at rest" ganglia, significantly more MEN were activated. The change in the ganglionic area correlated significantly with the number of additional recruited MEN. The additional recruitment of MEN was independent from nicotinic transmission and the ratio of active MEN in stretched ganglia shifted towards a nitrergic phenotype. CONCLUSION AND INFERENCES The higher number of active MEN with increasing stretch of the ganglia and their greater share of nitrergic phenotype might indicate their contribution to the adaptive relaxation. Further experiments are necessary to address the receptors involved in mechanotransduction.
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Affiliation(s)
- Sophia Mayr
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
| | - Kristin Elfers
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Gemma Mazzuoli-Weber
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
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Mayr S, Schliep R, Elfers K, Mazzuoli-Weber G. Mechanosensitive enteric neurons in the guinea pig gastric fundus and antrum. Neurogastroenterol Motil 2023; 35:e14674. [PMID: 37702071 DOI: 10.1111/nmo.14674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 07/16/2023] [Accepted: 08/28/2023] [Indexed: 09/14/2023]
Abstract
BACKGROUND Coping with the ingested food, the gastric regions of fundus, corpus, and antrum display different motility patterns. Intrinsic components of such patterns involving mechanosensitive enteric neurons (MEN) have been described in the guinea pig gastric corpus but are poorly understood in the fundus and antrum. METHODS To elucidate mechanosensitive properties of myenteric neurons in the gastric fundus and antrum, membrane potential imaging using Di-8-ANEPPS was applied. A small-volume injection led to neuronal compression. We analyzed the number of MEN and their firing frequency in addition to the involvement of selected mechanoreceptors. To characterize the neurochemical phenotype of MEN, we performed immunohistochemistry. KEY RESULTS In the gastric fundus, 16% of the neurons reproducibly responded to mechanical stimulation and thus were MEN. Of those, 83% were cholinergic and 19% nitrergic. In the antrum, 6% of the neurons responded to the compression stimulus, equally distributed among cholinergic and nitrergic MEN. Defunctionalizing the sensory extrinsic afferents led to a significant drop in the number of MEN in both regions. CONCLUSION We provided evidence for MEN in the gastric fundus and antrum and further investigated mechanoreceptors. However, the proportions of the chemical phenotypes of the MEN differed significantly between both regions. Further investigations of synaptic connections of MEN are crucial to understand the hardwired neuronal circuits in the stomach.
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Affiliation(s)
- Sophia Mayr
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
| | - Ronja Schliep
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Kristin Elfers
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Gemma Mazzuoli-Weber
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
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Truong Thuy Nguyen V, Taheri N, Choi EL, Kellogg TA, Linden DR, Hayashi Y. Insulin-Like Growth Factor1 Preserves Gastric Pacemaker Cells and Motor Function in Aging via ERK1/2 Activation. Cell Mol Gastroenterol Hepatol 2023; 16:369-383. [PMID: 37301443 PMCID: PMC10372898 DOI: 10.1016/j.jcmgh.2023.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 06/01/2023] [Accepted: 06/02/2023] [Indexed: 06/12/2023]
Abstract
BACKGROUND & AIMS Impaired gastric motor function in the elderly causes reduced food intake leading to frailty and sarcopenia. We previously found that aging-related impaired gastric compliance was mainly owing to depletion of interstitial cells of Cajal (ICC), pacemaker cells, and neuromodulator cells. These changes were associated with reduced food intake. Transformation-related protein 53-induced suppression of extracellular signal-regulated protein kinase (ERK)1/2 in ICC stem cell (ICC-SC) cell-cycle arrest is a key process for ICC depletion and gastric dysfunction during aging. Here, we investigated whether insulin-like growth factor 1 (IGF1), which can activate ERK in gastric smooth muscles and invariably is reduced with age, could mitigate ICC-SC/ICC loss and gastric dysfunction in klotho mice, a model of accelerated aging. METHODS Klotho mice were treated with the stable IGF1 analog LONG R3 recombinant human (rh) IGF1 (150 μg/kg intraperitoneally twice daily for 3 weeks). Gastric ICC/ICC-SC and signaling pathways were studied by flow cytometry, Western blot, and immunohistochemistry. Gastric compliance was assessed in ex vivo systems. Transformation-related protein 53 was induced with nutlin 3a and ERK1/2 signaling was activated by rhIGF-1 in the ICC-SC line. RESULTS LONG R3 rhIGF1 treatment prevented reduced ERK1/2 phosphorylation and gastric ICC/ICC-SC decrease. LONG R3 rhIGF1 also mitigated the reduced food intake and impaired body weight gain. Improved gastric function by LONG R3 rhIGF1 was verified by in vivo systems. In ICC-SC cultures, rhIGF1 mitigated nutlin 3a-induced reduced ERK1/2 phosphorylation and cell growth arrest. CONCLUSIONS IGF1 can mitigate age-related ICC/ICC-SC loss by activating ERK1/2 signaling, leading to improved gastric compliance and increased food intake in klotho mice.
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Affiliation(s)
- Vy Truong Thuy Nguyen
- Enteric Neuroscience Program, Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota; Gastroenterology Research Unit, Mayo Clinic College of Medicine and Science, Rochester, Minnesota
| | - Negar Taheri
- Enteric Neuroscience Program, Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota; Gastroenterology Research Unit, Mayo Clinic College of Medicine and Science, Rochester, Minnesota
| | - Egan L Choi
- Enteric Neuroscience Program, Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota; Gastroenterology Research Unit, Mayo Clinic College of Medicine and Science, Rochester, Minnesota
| | - Todd A Kellogg
- Department of Surgery, Mayo Clinic College of Medicine and Science, Rochester, Minnesota
| | - David R Linden
- Enteric Neuroscience Program, Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota
| | - Yujiro Hayashi
- Enteric Neuroscience Program, Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota; Gastroenterology Research Unit, Mayo Clinic College of Medicine and Science, Rochester, Minnesota.
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4
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Neural signalling of gut mechanosensation in ingestive and digestive processes. Nat Rev Neurosci 2022; 23:135-156. [PMID: 34983992 DOI: 10.1038/s41583-021-00544-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/16/2021] [Indexed: 12/29/2022]
Abstract
Eating and drinking generate sequential mechanosensory signals along the digestive tract. These signals are communicated to the brain for the timely initiation and regulation of diverse ingestive and digestive processes - ranging from appetite control and tactile perception to gut motility, digestive fluid secretion and defecation - that are vital for the proper intake, breakdown and absorption of nutrients and water. Gut mechanosensation has been investigated for over a century as a common pillar of energy, fluid and gastrointestinal homeostasis, and recent discoveries of specific mechanoreceptors, contributing ion channels and the well-defined circuits underlying gut mechanosensation signalling and function have further expanded our understanding of ingestive and digestive processes at the molecular and cellular levels. In this Review, we discuss our current understanding of the generation of mechanosensory signals from the digestive periphery, the neural afferent pathways that relay these signals to the brain and the neural circuit mechanisms that control ingestive and digestive processes, focusing on the four major digestive tract parts: the oral and pharyngeal cavities, oesophagus, stomach and intestines. We also discuss the clinical implications of gut mechanosensation in ingestive and digestive disorders.
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5
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O'Grady G, Gharibans AA, Du P, Huizinga JD. The gastric conduction system in health and disease: a translational review. Am J Physiol Gastrointest Liver Physiol 2021; 321:G527-G542. [PMID: 34549598 DOI: 10.1152/ajpgi.00065.2021] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Gastric peristalsis is critically dependent on an underlying electrical conduction system. Recent years have witnessed substantial progress in clarifying the operations of this system, including its pacemaking units, its cellular architecture, and slow-wave propagation patterns. Advanced techniques have been developed for assessing its functions at high spatiotemporal resolutions. This review synthesizes and evaluates this progress, with a focus on human and translational physiology. A current conception of the initiation and conduction of slow-wave activity in the human stomach is provided first, followed by a detailed discussion of its organization at the cellular and tissue level. Particular emphasis is then given to how gastric electrical disorders may contribute to disease states. Gastric dysfunction continues to grow in their prevalence and impact, and while gastric dysrhythmia is established as a clear and pervasive feature in several major gastric disorders, its role in explaining pathophysiology and informing therapy is still emerging. New insights from high-resolution gastric mapping are evaluated, together with historical data from electrogastrography, and the physiological relevance of emerging biomarkers from body surface mapping such as retrograde propagating slow waves. Knowledge gaps requiring further physiological research are highlighted.
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Affiliation(s)
- Gregory O'Grady
- Department of Surgery, The University of Auckland, Auckland, New Zealand.,Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Armen A Gharibans
- Department of Surgery, The University of Auckland, Auckland, New Zealand.,Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Peng Du
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Jan D Huizinga
- Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
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Cai W, Makwana R, Straface M, Gharibans A, Andrews PLR, Sanger GJ. Evidence for tetrodotoxin-resistant spontaneous myogenic contractions of mouse isolated stomach that are dependent on acetylcholine. Br J Pharmacol 2021; 179:1187-1200. [PMID: 34519057 PMCID: PMC9297954 DOI: 10.1111/bph.15685] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 09/03/2021] [Accepted: 09/06/2021] [Indexed: 12/24/2022] Open
Abstract
Background and Purpose Gastric pacemaker cells, interstitial cells of Cajal (ICC), are believed to initiate myogenic (non‐neuronal) contractions. These become damaged in gastroparesis, associated with dysrhythmic electrical activity and nausea. We utilised mouse isolated stomach to model myogenic contractions and investigate their origin and actions of interstitial cells of Cajal modulators. Experimental Approach Intraluminal pressure was recorded following distension with a physiological volume; tone, contraction amplitude and frequency were quantified. Compounds were bath applied. Key Results The stomach exhibited regular large amplitude contractions (median amplitude 9.0 [4.7–14.8] cmH2O, frequency 2.9 [2.5–3.4] c.p.m; n = 20), appearing to progress aborally. Tetrodotoxin (TTX, 10−6 M) had no effect on tone, frequency or amplitude but blocked responses to nerve stimulation. ω‐conotoxin GVIA (10−7 M) ± TTX was without effect on baseline motility. In the presence of TTX, (1) atropine (10−10–10−6 M) reduced contraction amplitude and frequency in a concentration‐related manner (pIC50 7.5 ± 0.3 M for amplitude), (2) CaCC channel (previously ANO1) inhibitors MONNA and CaCCinh‐A01 reduced contraction amplitude (significant at 10−5, 10−4 M respectively) and frequency (significant at 10−5 M), and (3), neostigmine (10−5 M) evoked a large, variable, increase in contraction amplitude, reduced by atropine (10−8–10−6 M) but unaffected (exploratory study) by the H1 receptor antagonist mepyramine (10−6 M). Conclusions and Implications The distended mouse stomach exhibited myogenic contractions, resistant to blockade of neural activity by TTX. In the presence of TTX, these contractions were prevented or reduced by compounds blocking interstitial cells of Cajal activity or by atropine and enhanced by neostigmine (antagonised by atropine), suggesting involvement of non‐neuronal ACh in their regulation.
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Affiliation(s)
- Weigang Cai
- Blizard Institute and the National Centre for Bowel Research, Barts The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Raj Makwana
- Blizard Institute and the National Centre for Bowel Research, Barts The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Marilisa Straface
- Blizard Institute and the National Centre for Bowel Research, Barts The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Armen Gharibans
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Paul L R Andrews
- Division of Biomedical Sciences, St George's University of London, London, UK
| | - Gareth J Sanger
- Blizard Institute and the National Centre for Bowel Research, Barts The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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7
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The role of enteric inhibitory neurons in intestinal motility. Auton Neurosci 2021; 235:102854. [PMID: 34329834 DOI: 10.1016/j.autneu.2021.102854] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 07/11/2021] [Indexed: 12/21/2022]
Abstract
The enteric nervous system controls much of the mixing and propulsion of nutrients along the digestive tract. Enteric neural circuits involve intrinsic sensory neurons, interneurons and motor neurons. While the role of the excitatory motor neurons is well established, the role of the enteric inhibitory motor neurons (IMNs) is less clear. The discovery of inhibitory transmission in the intestine in the 1960's in the laboratory of Geoff Burnstock triggered the search for the unknown neurotransmitter. It has since emerged that most neurons including the IMNs contain and may utilise more than one transmitter substances; for IMNs these include ATP, the neuropeptide VIP/PACAP and nitric oxide. This review distinguishes the enteric neural pathways underlying the 'standing reflexes' from the pathways operating physiologically during propulsive and non-propulsive movements. Morphological evidence in small laboratory animals indicates that the IMNs are located in the myenteric plexus and project aborally to the circular muscle, where they act by relaxing the muscle. There is ongoing 'tonic' activity of these IMNs to keep the intestinal muscle relaxed. Accommodatory responses to content further activate enteric pathways that involve the IMNs as the final neural element. IMNs are activated by mechanical and chemical stimulation induced by luminal contents, which activate intrinsic sensory enteric neurons and the polarised interneuronal ascending excitatory and descending inhibitory reflex pathways. The latter relaxes the muscle ahead of the advancing bolus, thus facilitating propulsion.
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8
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Hayashi Y, Asuzu DT, Bardsley MR, Gajdos GB, Kvasha SM, Linden DR, Nagy RA, Saravanaperumal SA, Syed SA, Toyomasu Y, Yan H, Chini EN, Gibbons SJ, Kellogg TA, Khazaie K, Kuro-o M, Machado Espindola Netto J, Singh MP, Tidball JG, Wehling-Henricks M, Farrugia G, Ordog T. Wnt-induced, TRP53-mediated Cell Cycle Arrest of Precursors Underlies Interstitial Cell of Cajal Depletion During Aging. Cell Mol Gastroenterol Hepatol 2020; 11:117-145. [PMID: 32771388 PMCID: PMC7672319 DOI: 10.1016/j.jcmgh.2020.07.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 07/29/2020] [Accepted: 07/30/2020] [Indexed: 12/16/2022]
Abstract
BACKGROUND & AIMS Gastric dysfunction in the elderly may cause reduced food intake, frailty, and increased mortality. The pacemaker and neuromodulator cells interstitial cells of Cajal (ICC) decline with age in humans, and their loss contributes to gastric dysfunction in progeric klotho mice hypomorphic for the anti-aging Klotho protein. The mechanisms of ICC depletion remain unclear. Klotho attenuates Wnt (wingless-type MMTV integration site) signaling. Here, we examined whether unopposed Wnt signaling could underlie aging-associated ICC loss by up-regulating transformation related protein TRP53 in ICC stem cells (ICC-SC). METHODS Mice aged 1-107 weeks, klotho mice, APCΔ468 mice with overactive Wnt signaling, mouse ICC-SC, and human gastric smooth muscles were studied by RNA sequencing, reverse transcription-polymerase chain reaction, immunoblots, immunofluorescence, histochemistry, flow cytometry, and methyltetrazolium, ethynyl/bromodeoxyuridine incorporation, and ex-vivo gastric compliance assays. Cells were manipulated pharmacologically and by gene overexpression and RNA interference. RESULTS The klotho and aged mice showed similar ICC loss and impaired gastric compliance. ICC-SC decline preceded ICC depletion. Canonical Wnt signaling and TRP53 increased in gastric muscles of klotho and aged mice and middle-aged humans. Overstimulated canonical Wnt signaling increased DNA damage response and TRP53 and reduced ICC-SC self-renewal and gastric ICC. TRP53 induction persistently inhibited G1/S and G2/M cell cycle phase transitions without activating apoptosis, autophagy, cellular quiescence, or canonical markers/mediators of senescence. G1/S block reflected increased cyclin-dependent kinase inhibitor 1B and reduced cyclin D1 from reduced extracellular signal-regulated kinase activity. CONCLUSIONS Increased Wnt signaling causes age-related ICC loss by up-regulating TRP53, which induces persistent ICC-SC cell cycle arrest without up-regulating canonical senescence markers.
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Affiliation(s)
- Yujiro Hayashi
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota,Gastroenterology Research Unit, Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota,Yujiro Hayashi, PhD, Mayo Clinic, Guggenheim 10, 200 First Street SW, Rochester, Minnesota 55906. fax: (507) 255-6318.
| | - David T. Asuzu
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota,Gastroenterology Research Unit, Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Michael R. Bardsley
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota,Gastroenterology Research Unit, Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Gabriella B. Gajdos
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota,Gastroenterology Research Unit, Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Sergiy M. Kvasha
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota,Gastroenterology Research Unit, Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - David R. Linden
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Rea A. Nagy
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota,Gastroenterology Research Unit, Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Siva Arumugam Saravanaperumal
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota,Gastroenterology Research Unit, Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Sabriya A. Syed
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota,Gastroenterology Research Unit, Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Yoshitaka Toyomasu
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota,Gastroenterology Research Unit, Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Huihuang Yan
- Division of Biomedical Statistics and Informatics, Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota
| | - Eduardo N. Chini
- Signal Transduction and Molecular Nutrition Laboratory, Kogod Aging Center and Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota
| | - Simon J. Gibbons
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | | | | | - Makoto Kuro-o
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas,Division of Anti-aging Medicine, Center for Molecular Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan
| | - Jair Machado Espindola Netto
- Signal Transduction and Molecular Nutrition Laboratory, Kogod Aging Center and Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota
| | | | - James G. Tidball
- Department of Integrative Biology and Physiology, University of California, Los Angeles, California
| | | | - Gianrico Farrugia
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Tamas Ordog
- Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota,Gastroenterology Research Unit, Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota,Center for Individualized Medicine, Mayo Clinic, Rochester, Minnesota,Correspondence Address correspondence to: Tamas Ordog, MD, Mayo Clinic, Guggenheim 10, 200 First Street SW, Rochester, Minnesota 55906. fax: (507) 255-6318.
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9
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Goyal RK, Guo Y, Mashimo H. Advances in the physiology of gastric emptying. Neurogastroenterol Motil 2019; 31:e13546. [PMID: 30740834 PMCID: PMC6850045 DOI: 10.1111/nmo.13546] [Citation(s) in RCA: 159] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 11/29/2018] [Accepted: 12/16/2018] [Indexed: 12/16/2022]
Abstract
There have been many recent advances in the understanding of various aspects of the physiology of gastric motility and gastric emptying. Earlier studies had discovered the remarkable ability of the stomach to regulate the timing and rate of emptying of ingested food constituents and the underlying motor activity. Recent studies have shown that two parallel neural circuits, the gastric inhibitory vagal motor circuit (GIVMC) and the gastric excitatory vagal motor circuit (GEVMC), mediate gastric inhibition and excitation and therefore the rate of gastric emptying. The GIVMC includes preganglionic cholinergic neurons in the DMV and the postganglionic inhibitory neurons in the myenteric plexus that act by releasing nitric oxide, ATP, and peptide VIP. The GEVMC includes distinct gastric excitatory preganglionic cholinergic neurons in the DMV and postganglionic excitatory cholinergic neurons in the myenteric plexus. Smooth muscle is the final target of these circuits. The role of the intramuscular interstitial cells of Cajal in neuromuscular transmission remains debatable. The two motor circuits are differentially regulated by different sets of neurons in the NTS and vagal afferents. In the digestive period, many hormones including cholecystokinin and GLP-1 inhibit gastric emptying via the GIVMC, and in the inter-digestive period, hormones ghrelin and motilin hasten gastric emptying by stimulating the GEVMC. The GIVMC and GEVMC are also connected to anorexigenic and orexigenic neural pathways, respectively. Identification of the control circuits of gastric emptying may provide better delineation of the pathophysiology of abnormal gastric emptying and its relationship to satiety signals and food intake.
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Affiliation(s)
- Raj K. Goyal
- Department of Medicine, VA Boston Healthcare SystemHarvard Medical SchoolBostonMassachusetts
| | - Yanmei Guo
- Department of Medicine, VA Boston Healthcare SystemHarvard Medical SchoolBostonMassachusetts
| | - Hiroshi Mashimo
- Department of Medicine, VA Boston Healthcare SystemHarvard Medical SchoolBostonMassachusetts
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10
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Piezo proteins: incidence and abundance in the enteric nervous system. Is there a link with mechanosensitivity? Cell Tissue Res 2018; 375:605-618. [PMID: 30324494 DOI: 10.1007/s00441-018-2926-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 09/10/2018] [Indexed: 10/28/2022]
Abstract
Piezo channels play fundamental roles in many physiological processes. Their presence and functional role in the enteric nervous system is still not known. We hypothesize that they play a role in mechanotransduction in enteric neurons. Our aims are to quantify the presence of both Piezo1 and 2 in enteric neurons throughout the gastrointestinal tract using immunohistochemistry and analyze their function(s) using neuroimaging techniques and pharmacological investigations. In order to perform a systematic and comparative study, we performed our experiments in gastrointestinal tissue from guinea pigs, mice and humans. Piezo1 (20-70%) is expressed by both enteric neuronal cell bodies and fibers in the myenteric and submucosal plexi of all the species investigated. Generally, Piezo1 expressing somata are more numerous in the submucosal plexus (50-80%) than in the myenteric plexus (15-35%) apart from the stomach where Piezo1 is expressed in up to 60% of cell bodies. Myenteric Piezo1 neurons mainly (60-100%) but not exclusively, also express nitric oxide synthase, a minority express choline acetyltransferase. In the submucosal plexus, Piezo1 neurons co-express vasoactive intestinal peptide (40-90%). Conversely, expression of Piezo2 is extremely rare in the somata of enteric neurons and is present in few neurites. In functional experiments, 38-76% of the mechanosensitive neurons expressed Piezo1 channels. Statistical analysis showed a positive significant correlation between mechanosensitive and Piezo1 positive neurons. However, pharmacological experiments using an activator and an inhibitor of Piezo channels did not demonstrate changes in mechanotransduction. A major role of Piezo1 in the mechanosensitivity of enteric neurons can be excluded.
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11
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Kugler EM, Michel K, Kirchenbüchler D, Dreissen G, Csiszár A, Merkel R, Schemann M, Mazzuoli-Weber G. Sensitivity to Strain and Shear Stress of Isolated Mechanosensitive Enteric Neurons. Neuroscience 2018; 372:213-224. [PMID: 29317262 DOI: 10.1016/j.neuroscience.2017.12.052] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 12/20/2017] [Accepted: 12/27/2017] [Indexed: 10/18/2022]
Abstract
Within the enteric nervous system, the neurons in charge to control motility of the gastrointestinal tract reside in a particular location nestled between two perpendicular muscle layers which contract and relax. We used primary cultured myenteric neurons of male guinea pigs to study mechanosensitivity of enteric neurons in isolation. Ultrafast Neuroimaging with a voltage-sensitive dye technique was used to record neuronal activity in response to shear stress and strain. Strain was induced by locally deforming the elastic cell culture substrate next to a neuron. Measurements showed that substrate strain was mostly elongating cells. Shear stress was exerted by hydrodynamic forces in a microchannel. Both stimuli induced excitatory responses. Strain activated 14% of the stimulated myenteric neurons that responded with a spike frequency of 1.9 (0.7/3.2) Hz, whereas shear stress excited only a few neurons (5.6%) with a very low spike frequency of 0 (0/0.6) Hz. Thus, shear stress does not seem to be an adequate stimulus for mechanosensitive enteric neurons (MEN) while strain activates enteric neurons in a relevant manner. Analyzing the adaptation behavior of MEN showed that shear stress activated rapidly/slowly/ultraslowly adapting MEN (2/62/36%) whereas strain only slowly (46%) and ultraslowly (54%) MEN. Paired experiments with strain and normal stress revealed three mechanosensitive enteric neuronal populations: one strain-sensitive (37%), one normal stress-sensitive (17%) and one strain- and stress-sensitive (46%). These results indicate that shear stress does not play a role in the neuronal control of motility but normal stress and strain.
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Affiliation(s)
- Eva Maria Kugler
- Human Biology, Technische Universität München, Freising-Weihenstephan, 85354, Germany.
| | - Klaus Michel
- Human Biology, Technische Universität München, Freising-Weihenstephan, 85354, Germany.
| | - David Kirchenbüchler
- Institute of Complex Systems - Biomechanics, Research Center Jülich, 52425 Jülich, Germany.
| | - Georg Dreissen
- Institute of Complex Systems - Biomechanics, Research Center Jülich, 52425 Jülich, Germany.
| | - Agnes Csiszár
- Institute of Complex Systems - Biomechanics, Research Center Jülich, 52425 Jülich, Germany.
| | - Rudolf Merkel
- Institute of Complex Systems - Biomechanics, Research Center Jülich, 52425 Jülich, Germany.
| | - Michael Schemann
- Human Biology, Technische Universität München, Freising-Weihenstephan, 85354, Germany.
| | - Gemma Mazzuoli-Weber
- Human Biology, Technische Universität München, Freising-Weihenstephan, 85354, Germany.
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12
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Mazzuoli-Weber G, Schemann M. Mechanosensitive enteric neurons in the guinea pig gastric corpus. Front Cell Neurosci 2015; 9:430. [PMID: 26578888 PMCID: PMC4630284 DOI: 10.3389/fncel.2015.00430] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 10/13/2015] [Indexed: 01/27/2023] Open
Abstract
For long it was believed that a particular population of enteric neurons, referred to as intrinsic primary afferent neuron (IPAN)s, encodes mechanical stimulation. We recently proposed a new concept suggesting that there are in addition mechanosensitive enteric neurons (MEN) that are multifunctional. Based on firing pattern MEN behaved as rapidly, slowly, or ultra-slowly adapting RAMEN, SAMEN, or USAMEN, respectively. We aimed to validate this concept in the myenteric plexus of the gastric corpus, a region where IPANs were not identified and existence of enteric sensory neurons was even questioned. The gastric corpus is characterized by a particularly dense extrinsic sensory innervation. Neuronal activity was recorded with voltage sensitive dye imaging after deformation of ganglia by compression (intraganglionic volume injection or von Fry hair) or tension (ganglionic stretch). We demonstrated that 27% of the gastric neurons were MEN and responded to intraganglionic volume injection. Of these 73% were RAMEN, 25% SAMEN, and 2% USAMEN with a firing frequency of 1.7 (1.1/2.2), 5.1 (2.2/7.7), and of 5.4 (5.0/15.5) Hz, respectively. The responses were reproducible and stronger with increased stimulus strength. Even after adaptation another deformation evoked spike discharge again suggesting a resetting mode of the mechanoreceptors. All MEN received fast synaptic input. Fifty five percent of all MEN were cholinergic and 45% nitrergic. Responses in some MEN significantly decreased after perfusion of TTX, low Ca(++)/high Mg(++) Krebs solution, capsaicin induced nerve defunctionalization and capsazepine indicating the involvement of TRPV1 expressing extrinsic mechanosensitive nerves. Half of gastric MEN responded to intraganglionic volume injection as well as to ganglionic stretch and 23% responded to stretch only. Tension-sensitive MEN were to a large proportion USAMEN (44%). In summary, we demonstrated for the first time compression and tension-sensitive MEN in the stomach; many of them responded to one stimulus modality only. Their proportions and the basic properties were similar to MEN previously identified by us in other intestinal region and species. Unlike in the intestine, the responsiveness of some gastric MEN is enhanced by extrinsic TRPV1 expressing visceral afferents.
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Affiliation(s)
| | - Michael Schemann
- Human Biology, Technische Universitaet Muenchen Freising, Germany
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The enteric nervous system and gastrointestinal innervation: integrated local and central control. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 817:39-71. [PMID: 24997029 DOI: 10.1007/978-1-4939-0897-4_3] [Citation(s) in RCA: 480] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The digestive system is innervated through its connections with the central nervous system (CNS) and by the enteric nervous system (ENS) within the wall of the gastrointestinal tract. The ENS works in concert with CNS reflex and command centers and with neural pathways that pass through sympathetic ganglia to control digestive function. There is bidirectional information flow between the ENS and CNS and between the ENS and sympathetic prevertebral ganglia.The ENS in human contains 200-600 million neurons, distributed in many thousands of small ganglia, the great majority of which are found in two plexuses, the myenteric and submucosal plexuses. The myenteric plexus forms a continuous network that extends from the upper esophagus to the internal anal sphincter. Submucosal ganglia and connecting fiber bundles form plexuses in the small and large intestines, but not in the stomach and esophagus. The connections between the ENS and CNS are carried by the vagus and pelvic nerves and sympathetic pathways. Neurons also project from the ENS to prevertebral ganglia, the gallbladder, pancreas and trachea.The relative roles of the ENS and CNS differ considerably along the digestive tract. Movements of the striated muscle esophagus are determined by neural pattern generators in the CNS. Likewise the CNS has a major role in monitoring the state of the stomach and, in turn, controlling its contractile activity and acid secretion, through vago-vagal reflexes. In contrast, the ENS in the small intestine and colon contains full reflex circuits, including sensory neurons, interneurons and several classes of motor neuron, through which muscle activity, transmucosal fluid fluxes, local blood flow and other functions are controlled. The CNS has control of defecation, via the defecation centers in the lumbosacral spinal cord. The importance of the ENS is emphasized by the life-threatening effects of some ENS neuropathies. By contrast, removal of vagal or sympathetic connections with the gastrointestinal tract has minor effects on GI function. Voluntary control of defecation is exerted through pelvic connections, but cutting these connections is not life-threatening and other functions are little affected.
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14
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Brijs J, Hennig GW, Axelsson M, Olsson C. Effects of feeding on in vivo motility patterns in the proximal intestine of shorthorn sculpin (Myoxocephalus scorpius). J Exp Biol 2014; 217:3015-27. [PMID: 24948631 PMCID: PMC4148186 DOI: 10.1242/jeb.101741] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 06/10/2014] [Indexed: 01/16/2023]
Abstract
This is the first study to catalogue the diverse array of in vivo motility patterns in a teleost fish and how they are affected by feeding. Video recordings of exteriorised proximal intestine from fasted and fed shorthorn sculpin (Myoxocephalus scorpius) were used to generate spatio-temporal maps to portray and quantify motility patterns. Propagating and non-propagating contractions were observed to occur at different frequencies and durations. The most apparent difference between the feeding states was that bands of relatively high amplitude contractions propagating slowly in the anal direction were observed in all fasted fish (N=10) but in only 35% of fed fish (N=11). Additionally, fed fish displayed a reduced frequency (0.21±0.03 versus 0.32±0.06 contractions min(-1)) and rhythmicity of these contractions compared with fasted fish. Although the underlying mechanisms of these slow anally propagating contractions differ from those of mammalian migrating motor complexes, we believe that they may play a similar role in shorthorn sculpin during the interdigestive period, to potentially remove food remnants and prevent the establishment of pathogens. 'Ripples' were the most prevalent contraction type in shorthorn sculpin and may be important during mixing and absorption. The persistence of shallow ripples and pendular movements of longitudinal muscle after tetrodotoxin (1 μmol l(-1)) treatment suggests these contractions were myogenic in origin. The present study highlights both similarities and differences in motility patterns between shorthorn sculpin and other vertebrates, as well as providing a platform to examine other aspects of gastrointestinal functions in fish, including the impact of environmental changes.
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Affiliation(s)
- Jeroen Brijs
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Grant W Hennig
- Department of Physiology and Cell Biology, University of Reno, NV, USA
| | - Michael Axelsson
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Catharina Olsson
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
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15
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Dinning PG, Wiklendt L, Omari T, Arkwright JW, Spencer NJ, Brookes SJH, Costa M. Neural mechanisms of peristalsis in the isolated rabbit distal colon: a neuromechanical loop hypothesis. Front Neurosci 2014; 8:75. [PMID: 24795551 PMCID: PMC3997013 DOI: 10.3389/fnins.2014.00075] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 03/26/2014] [Indexed: 11/13/2022] Open
Abstract
Propulsive contractions of circular muscle are largely responsible for the movements of content along the digestive tract. Mechanical and electrophysiological recordings of isolated colonic circular muscle have demonstrated that localized distension activates ascending and descending interneuronal pathways, evoking contraction orally and relaxation anally. These polarized enteric reflex pathways can theoretically be sequentially activated by the mechanical stimulation of the advancing contents. Here, we test the hypothesis that initiation and propagation of peristaltic contractions involves a neuromechanical loop; that is an initial gut distension activates local and oral reflex contraction and anal reflex relaxation, the subsequent movement of content then acts as new mechanical stimulus triggering sequentially reflex contractions/relaxations at each point of the gut resulting in a propulsive peristaltic contraction. In fluid filled isolated rabbit distal colon, we combined spatiotemporal mapping of gut diameter and intraluminal pressure with a new analytical method, allowing us to identify when and where active (neurally-driven) contraction or relaxation occurs. Our data indicate that gut dilation is associated with propagating peristaltic contractions, and that the associated level of dilation is greater than that preceding non-propagating contractions (2.7 ± 1.4 mm vs. 1.6 ± 1.2 mm; P < 0.0001). These propagating contractions lead to the formation of boluses that are propelled by oral active neurally driven contractions. The propelled boluses also activate neurally driven anal relaxations, in a diameter dependent manner. These data support the hypothesis that neural peristalsis is the consequence of the activation of a functional loop involving mechanical dilation which activates polarized enteric circuits. These produce propulsion of the bolus which activates further anally, polarized enteric circuits by distension, thus closing the neuromechanical loop.
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Affiliation(s)
- Phil G Dinning
- Department of Gastroenterology and Surgery, Flinders Medical Centre, Flinders University Bedford Park, SA, Australia ; Department of Human Physiology, School of Medicine, Flinders University Bedford Park, SA, Australia
| | - Lukasz Wiklendt
- Department of Human Physiology, School of Medicine, Flinders University Bedford Park, SA, Australia
| | - Taher Omari
- Department of Human Physiology, School of Medicine, Flinders University Bedford Park, SA, Australia ; Gastroenterology Unit, Child, Youth and Women's Health Service Adelaide, SA, Australia
| | | | - Nick J Spencer
- Department of Human Physiology, School of Medicine, Flinders University Bedford Park, SA, Australia
| | - Simon J H Brookes
- Department of Human Physiology, School of Medicine, Flinders University Bedford Park, SA, Australia
| | - Marcello Costa
- Department of Human Physiology, School of Medicine, Flinders University Bedford Park, SA, Australia
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16
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LePard KJ, Cellini J. Age-dependent slowing of enteric axonal transport in insulin-resistant mice. World J Gastroenterol 2013; 19:482-91. [PMID: 23382626 PMCID: PMC3558571 DOI: 10.3748/wjg.v19.i4.482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 11/20/2012] [Accepted: 12/15/2012] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate retrograde tracer transport by gastric enteric neurons in insulin resistant mice with low or high glycosylated hemoglobin (Hb).
METHODS: Under anesthesia, the retrograde tracer fluorogold was superficially injected into the fundus or antrum using a microsyringe in KK Cg-Ay/J mice prior to onset of type 2 diabetes mellitus (T2DM; 4 wk of age), at onset of T2DM (8 wk of age), and after 8, 16, or 24 wk of untreated T2DM and in age-matched KK/HIJ mice. Six days later, mice were sacrificed by CO2 narcosis followed by pneumothorax. Stomachs were removed and fixed. Sections from fundus, corpus and antrum were excised and mounted on a glass slide. Tracer-labeled neurons were viewed using a microscope and manually counted. Data were expressed as the number of neurons in short and long descending and ascending pathways and in local fundus and antrum pathways, and the number of neurons in all regions labeled after injection of tracer into either the fundus or the antrum.
RESULTS: By 8 wk of age, body weights of KKAy mice (n = 12, 34 ± 1 g) were heavier than KK mice (n = 17, 29 ± 1 g; F (4, 120) = 4.414, P = 0.002] and glycosylated Hb was higher [KK: (n = 7), 4.97% ± 0.04%; KKAy: (n = 6), 6.57% ± 0.47%; F (1, 26) = 24.748, P < 0.001]. The number of tracer labeled enteric neurons was similar in KK and KKAy mice of all ages in the short descending pathway [F (1, 57) = 2.374, P = 0.129], long descending pathway [F (1, 57) = 0.922, P = 0.341], local fundus pathway [F (1, 53) = 2.464, P = 0.122], local antrum pathway [F (1, 57) = 0.728, P = 0.397], and short ascending pathway [F (1, 53) = 2.940, P = 0.092]. In the long ascending pathway, fewer tracer-labeled neurons were present in KKAy as compared to KK mice [KK: (n = 34), 302 ± 17; KKAy: (n = 29), 230 ± 15; F (1, 53) = 8.136, P = 0.006]. The number of tracer-labeled neurons was decreased in all mice by 16 wk as compared to 8 wk of age in the short descending pathway [8 wk: (n = 15), 305 ± 26; 16 wk: (n = 13), 210 ± 30; F (4, 57) = 9.336, P < 0.001], local antrum pathway [8 wk: (n = 15), 349 ± 20; 16 wk: (n = 13), 220 ± 33; F (4, 57) = 8.920, P < 0.001], short ascending pathway [8 wk: (n = 14), 392 ± 15; 16 wk: (n = 14), 257 ± 33; F (4, 53) = 17.188, P < 0.001], and long ascending pathway [8 wk: (n = 14), 379 ± 39; 16 wk: (n = 14), 235 ± 26; F (4, 53) = 24.936, P < 0.001]. The number of tracer-labeled neurons decreased at 24 wk of age in the local fundus pathway [8 wk: (n = 14), 33 ± 11; 24 wk: (n = 12), 3 ± 2; F (4, 53) = 5.195, P = 0.001] and 32 wk of age in the long descending pathway [8 wk: (n = 15), 16 ± 3; 32 wk: (n = 12), 3 ± 2; F (4, 57) = 2.944, P = 0.028]. The number of tracer-labeled enteric neurons was correlated to final body weight for local fundus and ascending pathways [KK: (n = 34), r = -0.746, P < 0.001; KKAy: (n = 29), r = -0.842, P < 0.001] as well as local antrum and descending pathways [KK (n = 36), r = -0.660, P < 0.001; KKAy (n = 31), r = -0.622, P < 0.001]. In contrast, glycosylated Hb was not significantly correlated to number of tracer-labeled neurons [KK (n = 17), r = -0.164, P = 0.528; KKAy (n = 16), r = -0.078, P = 0.774].
CONCLUSION: Since uncontrolled T2DM did not uniformly impair tracer transport in gastric neurons, long ascending neurons may be more susceptible to persistent hyperglycemia and low effective insulin.
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17
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Kim DH, Kim YC, Choi W, Yun HY, Sung R, Kim HS, Kim H, Yoo RY, Park SM, Yun SJ, Song YJ, Xu WX, Lee SJ. High k(+)-induced relaxation by nitric oxide in human gastric fundus. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2012; 16:297-303. [PMID: 23118553 PMCID: PMC3484514 DOI: 10.4196/kjpp.2012.16.5.297] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Revised: 08/09/2012] [Accepted: 08/19/2012] [Indexed: 12/11/2022]
Abstract
This study was designed to elucidate high K(+)-induced relaxation in the human gastric fundus. Circular smooth muscle from the human gastric fundus greater curvature showed stretch-dependent high K(+) (50 mM)-induced contractions. However, longitudinal smooth muscle produced stretch-dependent high K(+)-induced relaxation. We investigated several relaxation mechanisms to understand the reason for the discrepancy. Protein kinase inhibitors such as KT 5823 (1 µM) and KT 5720 (1 µM) which block protein kinases (PKG and PKA) had no effect on high K(+)-induced relaxation. K(+) channel blockers except 4-aminopyridine (4-AP), a voltage-dependent K(+) channel (K(V)) blocker, did not affect high K(+)-induced relaxation. However, N(G)-nitro-L-arginine and 1H-(1,2,4)oxadiazolo (4,3-A)quinoxalin-1-one, an inhibitors of soluble guanylate cyclase (sGC) and 4-AP inhibited relaxation and reversed relaxation to contraction. High K(+)-induced relaxation of the human gastric fundus was observed only in the longitudinal muscles from the greater curvature. These data suggest that the longitudinal muscle of the human gastric fundus greater curvature produced high K(+)-induced relaxation that was activated by the nitric oxide/sGC pathway through a K(V) channel-dependent mechanism.
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Affiliation(s)
- Dae Hoon Kim
- Department of Surgery, Chungbuk National University College of Medicine, Cheongju 361-763, Korea
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18
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Kim YC, Choi W, Yun HY, Sung R, Yoo RY, Park SM, Yun SJ, Kim MJ, Song YJ, Xu WX, Lee SJ. Nitric Oxide-mediated Relaxation by High K in Human Gastric Longitudinal Smooth Muscle. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2011; 15:405-13. [PMID: 22359479 PMCID: PMC3282229 DOI: 10.4196/kjpp.2011.15.6.405] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Revised: 11/10/2011] [Accepted: 11/12/2011] [Indexed: 12/27/2022]
Abstract
This study was designed to elucidate high-K(+)induced response of circular and longitudinal smooth muscle from human gastric corpus using isometric contraction. Contraction from circular and longitudinal muscle stripes of gastric corpus greater curvature and lesser curvature were compared. Circular smooth muscle from corpus greater curvature showed high K(+) (50 mM)-induced tonic contraction. On the contrary, however, longitudinal smooth muscle strips showed high K(+) (50 mM)-induced sustained relaxation. To find out the reason for the discrepancy we tested several relaxation mechanisms. Protein kinase blockers like KT5720, PKA inhibitor, and KT5823, PKG inhibitor, did not affect high K(+)-induced relaxation. K(+) channel blockers like tetraethylammonium (TEA), apamin (APA), glibenclamide (Glib) and barium (Ba(2+)) also had no effect. However, N(G)-nitro-L-arginine (L-NNA) and 1H-(1,2,4) oxadiazolo (4,3-A) quinoxalin-1-one (ODQ), an inhibitor of soluble guanylate cyclase (sGC) and 4-AP (4-aminopyridine), voltage-dependent K(+) channel (K(V)) blocker, inhibited high K(+)-induced relaxation, hence reversing to tonic contraction. High K(+)-induced relaxation was observed in gastric corpus of human stomach, but only in the longitudinal muscles from greater curvature not lesser curvature. L-NNA, ODQ and K(V) channel blocker sensitive high K(+)-induced relaxation in longitudinal muscle of higher portion of corpus was also observed. These results suggest that longitudinal smooth muscle from greater curvature of gastric corpus produced high K(+)-induced relaxation which was activated by NO/sGC pathway and by K(V) channel dependent mechanism.
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Affiliation(s)
- Young Chul Kim
- Department of Physiology, Chungbuk National University, College of Medicine, Cheongju 361-763, Korea
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19
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Quantification of the effects of the volume and viscosity of gastric contents on antral and fundic activity in the rat stomach maintained ex vivo. Dig Dis Sci 2010; 55:3349-60. [PMID: 20198425 DOI: 10.1007/s10620-010-1164-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Accepted: 02/11/2010] [Indexed: 12/13/2022]
Abstract
AIMS The aim of this study was to examine the effect of varying the rheological properties of perfusate on the volume and muscular activity of the various compartments of the rat stomach. METHODS Image analysis was used to quantify the activity of the ex vivo stomach preparations when perfused according to a ramp profile. RESULTS The area of the fundus increased to a greater extent than that of the body when watery or viscous material was perfused. However, initial distension of the corpus was greater and occurred more rapidly when viscous material was perfused. Only the fundus expanded when perfusion followed the administration of verapamil. The frequency of antrocorporal contractions decreased significantly and the amplitude of antrocorporal contractions increased significantly with increase in gastric volume. The velocity of antrocorporal contractions did not vary with gastric volume but varied regionally in some preparations being faster distally than proximally. Neither the frequency, amplitude or velocity of antrocorporal contractions differed when pseudoplastic rather than watery fluid was perfused. However, the characteristics of antrocorporal contractions changed significantly when the stomach was perfused with material with rheological characteristics that induce different patterns of wall tension to those normally encountered. Hence, the mean frequency and speed of propagation of antrocorporal contractions increased and their direction of propagation became inconstant.
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20
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Hennig GW, Gregory S, Brookes SJH, Costa M. Non-peristaltic patterns of motor activity in the guinea-pig proximal colon. Neurogastroenterol Motil 2010; 22:e207-17. [PMID: 20059762 DOI: 10.1111/j.1365-2982.2009.01453.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND The guinea-pig proximal colon contains semi-solid feces which are propelled by intermittent neural peristaltic waves to the distal colon, where solid pellets are formed. Between propulsive periods, complex motor patterns underlie fluid re-absorption and mixing of contents. METHODS Spatio-temporal analysis of video recordings were used to investigate neural and myogenic patterns of non-peristaltic motor activity. KEY RESULTS At low distension (6 cmH(2)O), two major motor patterns were seen. Narrow rings of constriction (abrupt contractions) occurred at 19 cpm. These previously undescribed contractions occurred, almost simultaneously, at many points along the preparation, with a calculated propagation velocity of 110 mm s(-1). They were abolished by hexamethonium and by tetrodotoxin, indicating they were neurally mediated. Inhibition of nitric oxide synthase resulted in increased frequency of 'abrupt contractions' suggesting ongoing inhibitory modulation by endogenous nitric oxide. After tetrodotoxin, another distinct motor pattern was revealed; 'ripples'(1) consisted of shallow rings of contraction, occurring at 18 cpm and propagating at 2.7-2.9 mm s(-1) orally or aborally from multiple initiation sites. The frequency of 'ripples' increased as intraluminal pressure was raised, becoming very irregular at high distensions. L-type calcium channel blockers and openers affected the amplitude of 'ripples'. No frequency gradient of 'ripples' along the proximal colon was detected. This absence explains the multiple initiation sites which often shifted over time, and the oral and aboral propagation of 'ripples'. CONCLUSIONS & INFERENCES The interaction of myogenic 'ripples' with neurogenic 'abrupt contractions' generates localized alternating rings of contractions and dilatation, well suited to effective mixing of contents.
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Affiliation(s)
- G W Hennig
- Department of Human Physiology & Centre for Neuroscience, Flinders University, Adelaide, SA, Australia.
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21
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Forrest AS, Hennig GW, Jokela-Willis S, Park CD, Sanders KM. Prostaglandin regulation of gastric slow waves and peristalsis. Am J Physiol Gastrointest Liver Physiol 2009; 296:G1180-90. [PMID: 19359421 PMCID: PMC2697952 DOI: 10.1152/ajpgi.90724.2008] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Gastric emptying depends on functional coupling of slow waves between the corpus and antrum, to allow slow waves initiated in the gastric corpus to propagate to the pyloric sphincter and generate gastric peristalsis. Functional coupling depends on a frequency gradient where slow waves are generated at higher frequency in the corpus and drive the activity of distal pacemakers. Simultaneous intracellular recording from corpus and antrum was used to characterize the effects of PGE(2) on slow waves in the murine stomach. PGE(2) increased slow-wave frequency, and this effect was mimicked by EP(3), but not by EP(2), receptor agonists. Chronotropic effects were due to EP(3) receptors expressed by intramuscular interstitial cells of Cajal because these effects were not observed in W/W(V) mice. Although the integrated chronotropic effects of EP(3) receptor agonists were deduced from electrophysiological experiments, no clear evidence of functional uncoupling was observed with two-point electrical recording. Gastric peristalsis was also monitored by video imaging and spatiotemporal maps to study the impact of chronotropic agonists on propagating contractions. EP(3) receptor agonists increased the frequency of peristaltic contractions and caused ectopic sites of origin and collisions of peristaltic waves. The impact of selective regional application of chronotropic agonists was investigated by use of a partitioned bath. Antral slow waves followed enhanced frequencies induced by stimulation of the corpus, and corpus slow waves followed when slow-wave frequency was elevated in the antrum. This demonstrated reversal of slow-wave propagation with selective antral chronotropic stimulation. These studies demonstrate the impact of chronotropic agonists on regional intrinsic pacemaker frequency and integrated gastric peristalsis.
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Affiliation(s)
- Abigail S. Forrest
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Grant W. Hennig
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Sari Jokela-Willis
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Chong Doo Park
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Kenton M. Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
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22
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Nguyen NQ, Fraser RJ, Bryant LK, Chapman M, Holloway RH. Diminished functional association between proximal and distal gastric motility in critically ill patients. Intensive Care Med 2008; 34:1246-55. [PMID: 18297265 DOI: 10.1007/s00134-008-1036-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2007] [Accepted: 12/27/2007] [Indexed: 12/21/2022]
Abstract
OBJECTIVE This study examined the effects of critical illness on the relationship between proximal and distal gastric motor activity during fasting and duodenal nutrient stimulation. DESIGN Prospective, case-controlled study. PATIENTS AND PARTICIPANTS Ten critically ill patients and ten healthy volunteers. INTERVENTIONS Concurrent proximal gastric (barostat) and antro-pyloro-duodenal (manometry) motility were recorded during fasting and during two 60-min duodenal nutrient infusions (Ensure at 1 kcal/min and 2 kcal/min) in random order, separated by a 2-h wash-out period. RESULTS Baseline proximal gastric volumes were similar between the two groups. At 10 min nutrient-induced fundic relaxation was lower in patients than healthy subjects (45 +/- 26 vs. 196 +/- 29 ml). In patients the frequency and volume amplitude of fundic waves were also lower. There were fewer propagated antral waves in patients than in healthy subjects during both fasting and nutrient infusion. These were more retrograde, shorter in length and associated with a pyloric contraction. The proportion of fundic waves followed by a distally propagated antral wave was significantly less in patients (0%, 0-8%) than controls 36% (11-44%). CONCLUSIONS In critical illness, in addition to impairment of proximal and distal gastric motor activity, the association between the two gastric regions is abnormal. This disturbance may interfere with meal distribution and further contribute to slow gastric emptying in these patients.
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Affiliation(s)
- Nam Q Nguyen
- Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, North Terrace, SA, Australia.
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Nguyen NQ, Fraser RJ, Bryant LK, Holloway RH. Functional association between proximal and distal gastric motility during fasting and duodenal nutrient stimulation in humans. Neurogastroenterol Motil 2007; 19:638-45. [PMID: 17640178 DOI: 10.1111/j.1365-2982.2007.00919.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A functional integration exists between proximal and distal gastric motor activity in dogs but has not been demonstrated in humans. To determine the relationship between proximal and distal gastric motor activity in humans. Concurrent proximal (barostat) and distal (antro-pyloro-duodenal (APD) manometry) gastric motility were recorded in 10 healthy volunteers (28 +/- 3 years) during (i) fasting and (ii) two 60-min duodenal infusions of Ensure((R)) (1 and 2 kcal min(-1)) in random order. Proximal and APD motor activity and the association between fundic and propagated antral waves (PAWs) were determined. During fasting, 32% of fundic waves (FWs) were followed by a PAW. In a dose-dependent fashion, duodenal nutrients (i) increased proximal gastric volume, (ii) reduced fundic and antral wave (total and propagated) activity, and (iii) increased pyloric contractions. The proportion of FWs followed by a distal PAW was similar between both infusions and did not differ from fasting. During nutrient infusion, nearly all PAWs were antegrade, propagated over a shorter distance and less likely to traverse the pylorus, compared with fasting. In humans, a functional association exists between proximal and distal gastric motility during fasting and duodenal nutrient stimulation. This may have a role in optimizing intra-gastric meal distribution.
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Affiliation(s)
- N Q Nguyen
- Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, Adelaide, SA 5000, Australia.
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24
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Abstract
The gastrointestinal (GI) tract must balance ostensibly opposite functions. On the one hand, it must undertake the process of digestion and absorption of nutrients. At the same time, the GI tract must protect itself from potential harmful antigenic and pathogenic material. Central to these processes is the ability to 'sense' the mechanical and chemical environment in the gut wall and lumen in order to orchestrate the appropriate response that facilitates nutrient assimilation or the rapid expulsion through diarrhoea and/or vomiting. In this respect, the GI tract is richly endowed with sensory elements that monitor the gut environment. Enteric neurones provide one source of such sensory innervation and are responsible for the ability of the decentralized gut to perform complex reflex functions. Extrinsic afferents not only contribute to this reflex control, but also contribute to homeostatic mechanisms and can give rise to sensations, under certain circumstances. The enteric and extrinsic sensory mechanisms share a number of common features but also some remarkably different properties. The purpose of this review is to summarize current views on sensory processing within both the enteric and extrinsic innervation and to specifically address the pharmacology of nociceptive extrinsic sensory pathways.
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Affiliation(s)
- L A Blackshaw
- Nerve Gut Research Laboratory, Hanson Institute, Royal Adelaide Hospital, University of Adelaide, Adelaide, SA, Australia
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25
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Dixit D, Zarate N, Liu LWC, Boreham DR, Huizinga JD. Interstitial cells of Cajal and adaptive relaxation in the mouse stomach. Am J Physiol Gastrointest Liver Physiol 2006; 291:G1129-36. [PMID: 16891301 DOI: 10.1152/ajpgi.00518.2005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Interstitial cells of Cajal (ICC) are proposed to play a role in stretch activation of nerves and are under intense investigation for potential roles in enteric innervation. Most data to support such roles come from in vitro studies with muscle strips whereas data at the whole organ level are scarce. To obtain insight into the role of ICC in distention-induced motor patterns developing at the organ level, we studied distension-induced adaptive relaxation in the isolated whole stomach of wild-type and W/W(v) mice. A method was developed to assess gastric adaptive relaxation that gave quantitative information on rates of pressure development and maximal adaptive relaxation. Pressure development was monitored throughout infusion of 1 ml of solution over a 10-min period. The final intraluminal pressure was sensitive to blockade of nitric oxide synthase, in wild-type and W/W(v) mice to a similar extent, indicating NO-mediated relaxation in W/W(v) mice. Adaptive relaxation occurred between 0.2 and 0.5 ml of solution infusion; this reflex was abolished by TTX, was not sensitive to blockade of nitric oxide synthase, but was abolished by apamin, suggesting that ATP and not nitric oxide is the neurotransmitter responsible for this intrinsic reflex. Despite the absence of intramuscular ICC (ICC-IM), normal gastric adaptive relaxation occurred in the W/W(v) stomach. Because pressure development was significantly lower in W/W(v) mice compared with wild type in all the conditions studied, including in the presence of TTX, ICC-IM may play a role in development of myogenic tone. In conclusion, a mouse model was developed to assess the intrinsic component of gastric accommodation. This showed that ICC-IM are not essential for activation of intrinsic sensory nerves nor ATP-driven adaptive relaxation nor NO-mediated relaxation in the present model. ICC-IM may be involved in regulation of (distention-induced) myogenic tone.
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Affiliation(s)
- Devika Dixit
- Intestinal Disease Research Program, Department of Medicine, McMaster University, Hamilton, Ontario, Canada
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26
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Abstract
There has been considerable speculation about the function of interstitial cells of Cajal (ICC) since their discovery more than 100 years ago. It has been difficult to study these cells under native conditions, but great insights about the function of ICC have come from studies of genetic models with loss-of function mutations in the Kit signalling pathway. First it was discovered that signalling via Kit (a receptor tyrosine kinase) was vital for the development and maintenance of the ICC phenotype in gastrointestinal (GI) muscles. In compound heterozygotes (W/W(V) and Sl/Sl(d) animals), where there are partial loss-of-function mutations in Kit receptors or Kit ligand (stem cell factor), ICC failed to develop in various regions of the GI tract, but no major changes in the smooth muscle layers or enteric nervous system occurred in the absence of these cells. Animals with these mutations provided an unprecedented opportunity to understand the role of ICC in GI motor function, and it is now clear from these studies that ICC serve as: (i) pacemaker cells, generating the spontaneous electrical rhythms of the gut known as slow waves; (ii) a propagation pathway for slow waves so that large areas of the musculature can be entrained to a dominant pacemaker frequency; (iii) mediators of excitatory cholinergic and inhibitory nitrergic neural inputs from the enteric nervous system, and (iv) stretch receptors that modulate membrane potential and electrical slow wave frequency. This review describes the use of genetic models to understand the important physiological role of ICC in the GI tract.
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Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA.
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27
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Thacker M, Zhang FL, Jungnickel SR, Furness JB. Binding of isolectin IB4 to neurons of the mouse enteric nervous system. J Mol Histol 2006; 37:61-8. [PMID: 16773225 DOI: 10.1007/s10735-006-9033-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2006] [Accepted: 05/10/2006] [Indexed: 10/24/2022]
Abstract
The plant lectin, IB4, binds to primary afferent neurons of dorsal root and trigeminal ganglia, where it is selective for nociceptive neurons. In the enteric nervous system of the guinea-pig IB4 labels intrinsic primary afferent neurons, which are believed to have roles as nociceptors. Here we investigate whether IB4 binding is also a marker of intrinsic primary afferent neurons in the mouse. Neurons that bound IB4 were common in the enteric plexuses of the small intestine and colon. Labeled neurons were rare in the stomach, and absent from the esophagus and gallbladder. Binding was to the cell surface, initial parts of axons and to clumps in the cytoplasm. Similar binding occurred on small and medium sized neurons of dorsal root, nodose and trigeminal ganglia. In the enteric nervous system, IB4 revealed large round or oval (type II) neurons, type I neurons with prominent laminar dendrites and small neurons of myenteric ganglia. The type II neurons were immunoreactive for calretinin, and some type I neurons were immunoreactive for nitric oxide synthase. Most neurons in the submucosal ganglia bound IB4, and some of these were vasoactive intestinal peptide immunoreactive. Thus IB4 binds to specific subgroups of enteric neurons in the mouse. These include intrinsic primary afferent neurons, but other neurons, including secretomotor neurons, are labeled. The results suggest that IB4 is not a specific label for enteric nociceptive neurons.
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Affiliation(s)
- Michelle Thacker
- Department of Anatomy & Cell Biology and Centre for Neuroscience, University of Melbourne, Parkville, Victoria 3010, Australia
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28
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Abstract
Gastroduodenal physiology is traditionally understood in terms of motor-secretory functions and their electrical, neural and hormonal controls. In contrast, the fluid-mechanical functions that retain and disperse particles, expose substrate to enzymes, or replenish the epithelial boundary with nutrients are little studied. Current ultrasound and magnetic resonance imaging allows to visualize processes critical to digestion like mixing, dilution, swelling, dispersion and elution. Methodological advances in fluid mechanics allow to numerically analyse the forces promoting digestion. Pressure and flow fields, the shear stresses dispersing particles or the effectiveness of bolus mixing can be computed using information on boundary movements and on the luminal contents. These technological advances promise many additional insights into the mechanical processes that promote digestion and absorption.
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Affiliation(s)
- K Schulze
- Gastroenterology Research, VAMC and University of Iowa, Iowa City, IA 52242, USA.
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29
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Toyoshima M, Takeuchi T, Goto H, Mukai K, Shintani N, Hashimoto H, Baba A, Hata F. Roles of PACAP and PHI as inhibitory neurotransmitters in the circular muscle of mouse antrum. Pflugers Arch 2005; 451:559-68. [PMID: 16292577 DOI: 10.1007/s00424-005-1491-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2005] [Accepted: 07/04/2005] [Indexed: 11/24/2022]
Abstract
Mediators of neurogenic responses of the gastric antrum were studied in wild-type and pituitary adenylate cyclase-activating polypeptide (PACAP) -knockout (KO) mice. Electrical field stimulation (EFS) to the circular muscle strips of the wild-type mouse antrum induced a triphasic response; rapid transient relaxation and contraction, and sustained relaxation that was prolonged for an extended period after the end of EFS. The transient relaxation and contraction were completely inhibited by L-nitroarginine and atropine, respectively. The sustained relaxation was significantly inhibited by a PACAP receptor antagonist, PACAP(6-38). The antral strips prepared from PACAP-KO mice unexpectedly exhibited a tri-phasic response. However, the sustained relaxation was decreased to about one-half of that observed in wild-type mice. PACAP(6-38) inhibited EFS-induced sustained relaxation (33.5% of control) in PACAP-KO mice. Anti-peptide histidine isoleucine (PHI) serum partially (the 30% inhibition) or significantly (the 60% inhibition) inhibited the sustained relaxations in the wild-type and PACAP-KO mice, respectively. The immunoreactivities to the anti-PACAP and anti-PHI serums were found in myenteric ganglia of the mouse antrum. These results suggest that nitric oxide and acetylcholine mediate the transient relaxation and contraction, respectively, and that PACAP and PHI separately mediate the sustained relaxation in the antrum of the mouse stomach.
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Affiliation(s)
- Makiko Toyoshima
- Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Science, Osaka Prefecture University, Sakai, Japan
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30
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Abstract
AIM: To examine the sensory and motor response(s) of the stomach following fundic distention and to assess whether cholinergic mechanisms influence these responses.
METHODS: Fundic tone, gastric sensory responses and antral motility were evaluated in eight healthy volunteers after a probe with two sensors was placed in the antrum and a highly compliant balloon in the fundus. Isobaric balloon distentions were performed with a barostat. Study was repeated in six volunteers after intravenous atropine was given.
RESULTS: Fundic distention induced large amplitude antral contractions in all subjects. The area under the curve was higher (P<0.05) during fundic distention. First sensation was reported at 12±4 mmHg, moderate sensation at 18±4 mmHg and discomfort at 21±4 mmHg. Discomfort was associated with a decrease in antral motility. After atropine was given, the area under the curve of pressure waves and fundic tone decreased (P<0.05). Sensory thresholds were not affected.
CONCLUSIONS: Fundic balloon distention induces an antral motor response, the fundo-antral reflex, which in part may be mediated by cholinergic mechanisms.
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Affiliation(s)
- Satish S C Rao
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, USA.
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31
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Hashitani H, Garcia-Londoño AP, Hirst GDS, Edwards FR. Atypical slow waves generated in gastric corpus provide dominant pacemaker activity in guinea pig stomach. J Physiol 2005; 569:459-65. [PMID: 16223760 PMCID: PMC1464236 DOI: 10.1113/jphysiol.2005.097907] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
When intracellular recordings were made from the circular layer of the intact muscular wall of the isolated guinea pig gastric corpus, an ongoing regular high frequency discharge of slow waves was detected even though this region lacked myenteric interstitial cells. When slow waves were recorded from preparations consisting of both the antrum and the corpus, slow waves of identical frequency, but with different shapes, were generated in the two regions. Corporal slow waves could be distinguished from antral slow waves by their time courses and amplitudes. Corporal slow waves, like antral slow waves, were abolished by buffering the internal concentration of calcium ions, [Ca2+]i, to low levels, or by caffeine, 2-aminoethoxydiphenyl borate or the chloride channel blocker DIDS. Corporal preparations demonstrated an ongoing discharge of unitary potentials, as has been found in all other tissues containing interstitial cells. The experiments show that the corpus provides the dominant pacemaker activity which entrains activity in other regions of the stomach and it is suggested that this activity is generated by corporal intramuscular interstitial cells.
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Affiliation(s)
- Hikaru Hashitani
- Division of Neuroscience, John Curtin School of Medical Research, Canberra, ACT 0200, Australia
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32
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Won KJ, Sanders KM, Ward SM. Interstitial cells of Cajal mediate mechanosensitive responses in the stomach. Proc Natl Acad Sci U S A 2005; 102:14913-8. [PMID: 16204383 PMCID: PMC1253552 DOI: 10.1073/pnas.0503628102] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Changes in motor activity are a basic response to filling of smooth muscle organs. Responses to gastric filling, for example, are thought to be regulated by neural reflexes. Here, we demonstrate a previously uncharacterized aspect of stretch-dependent responses in visceral smooth muscles that is mediated by mechanosensitive interstitial cells of Cajal. Length ramps were applied to the murine antral muscles while recording intracellular electrical activity and isometric force. Stretching muscles by an average of 27 +/- 1% of resting length resulted in 5 mN of force. Increasing length caused membrane depolarization and increased slow-wave frequency. The responses were dependent on the rate of stretch. Stretch-dependent responses were not inhibited by neuronal antagonists or nifedipine. Increases in slow-wave frequency, but not membrane depolarization, were inhibited by reducing external Ca(2+) (100 microM) and by Ni(2+) (250 microM). Responses to stretch were inhibited by indomethacin (1 microM) and were absent in cyclooxygenase II-deficient mice, suggesting that cyclooxygenase II-derived eicosanoids may mediate these responses. Dual microelectrode impalements of muscle cells within the corpus and antrum showed that stretch-induced changes in slow-wave frequency uncoupled proximal-to-distal propagation of slow waves. This uncoupling could interfere with gastric peristalsis and impede gastric emptying. Stretch of antral muscles of W/W(V) mice, which lack intramuscular interstitial cells of Cajal, did not affect membrane depolarization or slow-wave frequency. These data demonstrate a previously uncharacterized nonneural stretch reflex in gastric muscles and provide physiological evidence demonstrating a mechanosensitive role for interstitial cells of Cajal in smooth muscle tissues.
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Affiliation(s)
- Kyung-Jong Won
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
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33
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Römer M, Painsipp E, Schwetz I, Holzer P. Facilitation of gastric compliance and cardiovascular reaction by repeated isobaric distension of the rat stomach. Neurogastroenterol Motil 2005; 17:399-409. [PMID: 15916627 PMCID: PMC4370837 DOI: 10.1111/j.1365-2982.2005.00649.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Gastric distension causes cardiovascular reactions and enhances gastric compliance. Here, we investigated how these responses are related to each other, whether they change upon repeated distension and which neural mechanisms are involved. Mean arterial blood pressure (MAP) in phenobarbital-anaesthetized rats was recorded from a carotid artery and gastric compliance determined with an electronic barostat. Runs of intermittent gastric distension were generated by stepwise increments (5 mmHg) of intragastric (IG) pressure. While gastric compliance peaked at IG pressures of 20 mmHg, the change in MAP (predominantly hypotension) was largest at IG pressures beyond 30 mmHg. Repeated distension enhanced the MAP response to IG pressures beyond 35 mmHg, whereas gastric compliance was facilitated primarily at IG pressures below 20 mmHg. This facilitation of gastric compliance depended on the magnitude of the preceding distension. The MAP response to distension was enhanced by nitric oxide synthase inhibition, inhibited by subdiaphragmatic vagotomy but hardly affected by coeliac ganglionectomy. The facilitation of gastric compliance was changed by vagotomy in a complex manner but left unaltered by the other interventions. These findings show that isobaric gastric distension elicits both MAP and gastric compliance responses whose characteristics, mechanisms and sensitization properties differ profoundly.
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Affiliation(s)
- M Römer
- Department of Experimental and Clinical Pharmacology, Medical University of Graz, Graz, Austria
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34
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Hennig GW, Hirst GDS, Park KJ, Smith CB, Sanders KM, Ward SM, Smith TK. Propagation of pacemaker activity in the guinea-pig antrum. J Physiol 2004; 556:585-99. [PMID: 14754999 PMCID: PMC1664942 DOI: 10.1113/jphysiol.2003.059055] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Cyclical periods of depolarization (slow waves) underlie peristaltic contractions involved in mixing and emptying of contents in the gastric antrum. Slow waves originate from a myenteric network of interstitial cells of Cajal (ICC-MY). In this study we have visualized the sequence and propagation of Ca(2+) transients associated with pacemaker potentials in the ICC network and longitudinal (LM) and circular muscle (CM) layers of the isolated guinea-pig gastric antrum. Gastric antrum was dissected to reveal the ICC-MY network, loaded with Fluo-4 AM and activity was monitored at 37 degrees C. Ca(2+) waves propagated throughout the ICC-MY network at an average velocity of 3.24 +/- 0.12 mm s(-1) at a frequency of 4.87 +/- 0.16 cycles min(-1) (n= 4). The propagation of the Ca(2+) wave often appeared 'step-like', with separate regions of the network being activated after variable delays. The direction of propagation was highly variable (Delta angle of propagation 44.3 +/- 10.9 deg per cycle) and was not confined to the axes of the longitudinal or circular muscle. Ca(2+) waves appeared to spread out radially from the site of initiation. The initiating Ca(2+) wave in ICC-MY was correlated to secondary Ca(2+) waves in intramuscular interstitial cells of Cajal, ICC-IM, and smooth muscle cells, and the local distortion (contraction) in a field of view. TTX (1 microm) had little effect on slow wave or pacemaker potential activity, but 2-APB (50 microm) blocked all Ca(2+) waves, indicating a pivotal role for intracellular Ca(2+) stores. Nicardipine (2 microm) eliminated the Ca(2+) transient generated by smooth muscle, but did not affect the fast upstroke associated with ICC-MY. These results indicate that slow waves follow a sequence of activation, beginning with the ICC-MY and ICC-IM network, followed later by a sustained Ca(2+) transient in the muscle layers that is responsible for contraction.
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Affiliation(s)
- G W Hennig
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada 89557, USA
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35
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Pimont S, Bruley Des Varannes S, Le Neel JC, Aubert P, Galmiche JP, Neunlist M. Neurochemical coding of myenteric neurones in the human gastric fundus. Neurogastroenterol Motil 2003; 15:655-62. [PMID: 14651601 DOI: 10.1046/j.1350-1925.2003.00442.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The major functions of the stomach are under the control of the enteric nervous system (ENS), but the neuronal circuits involved in this control are largely unknown in humans. Enteric neurones can be characterized by their neuromediator or marker content, i.e. by neurochemical coding. The purpose of this study was to characterize the presence and co-localization of neurotransmitters in myenteric neurones of the human gastric fundus. Choline acetyltransferase (ChAT), neurone-specific enolase (NSE), vasoactive intestinal polypeptide (VIP), nitric oxide synthase (NOS), substance P (SP) were detected by immunohistochemical methods in whole mounts of gastric fundus myenteric plexus (seven patients). Antibodies against ChAT and NOS labelled the majority of myenteric neurones identified by NSE (57.2 +/- 5.6% and 40.8 +/- 4.5%, respectively; mean +/- SD). The proportions of VIP- and SP-immunoreactive neurones were significantly smaller, constituting 19.6 +/- 6.9% and 16.0 +/- 3.7%, respectively. Co-localization studies revealed five major populations representing over 75% of the myenteric neurones: ChAT/-, 30.1 +/- 6.1%; NOS/-, 24.2 +/- 4.4%; ChAT/SP/-, 8.3 +/- 3.1%; NOS/VIP/-, 7.2 +/- 6.0%; ChAT/VIP/-, 4.9 +/- 2.6. Some similarities are apparent in the neurochemical coding of myenteric neurones in the stomach and intestine of humans, and between the stomach of humans and animals, but striking differences exist. The precise functional role of the neurochemically identified classes of neurones remains to be determined.
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Affiliation(s)
- S Pimont
- INSERM U 539, Place Alexis Ricordeau, Nantes, France CIC-INSERM, Place Alexis Ricordeau, Nantes, France.
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36
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Meedeniya ACB, Schloithe AC, Toouli J, Saccone GTP. Characterization of the intrinsic and extrinsic innervation of the gall bladder epithelium in the Australian Brush-tailed possum (Trichosurus vulpecula). Neurogastroenterol Motil 2003; 15:383-92. [PMID: 12846726 DOI: 10.1046/j.1365-2982.2003.00417.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Intrinsic neurones of the gall bladder modulate its function. Nitric oxide synthase (NOS) and vasoactive intestinal polypeptide (VIP) are present in gall bladder neurones and nitric oxide and VIP modulate its epithelial functions. As an extensive extrinsic innervation of the gall bladder is also present, the source of the epithelial innervation is unclear. In this study the source of the gall bladder epithelial innervation is defined. Immunoreactivity for VIP, NOS, substance P (SP), calcitonin gene related peptide (CGRP) and tyrosine hydroxylase (TH) in organotypic cultured and freshly fixed gall bladder were compared. Retrograde tracing in vitro from the epithelium was used to identify putative intrinsic secretomotor neurones, which were then characterized by immunohistochemistry. Abundant spinal afferent and sympathetic innervation of the gall bladder epithelium was demonstrated by CGRP/SP and TH immunohistochemistry, respectively. The intrinsic secretomotor innervation of the epithelium is derived exclusively from neurones of the subepithelial plexus. A majority of these neurones were immunoreactive for NOS. Some of the NOS-immunoreactive neurones of the subepithelial plexus also contained VIP and/or SP. Gall bladder subepithelial plexus neurones, containing NOS and/or VIP/SP, innervate the epithelium, as do extrinsic neurones.
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Affiliation(s)
- A C B Meedeniya
- Department of General and Digestive Surgery, Centre for Neuroscience, Flinders University, Flinders Medical Centre, Australia
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37
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Holzer P, Painsipp E, Jocic M, Heinemann A. Acid challenge delays gastric pressure adaptation, blocks gastric emptying and stimulates gastric fluid secretion in the rat. Neurogastroenterol Motil 2003; 15:45-55. [PMID: 12588468 DOI: 10.1046/j.1365-2982.2003.00382.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Functional dyspepsia can be associated with impaired gastric relaxation in response to food intake and delayed gastric emptying. In this study, we investigated whether luminal hydrochloric acid (HCl) may reproduce these motor alterations in phenobarbital-anaesthetized rats via activation of extrinsic neural pathways. Intragastric pressure (IGP) changes induced by a 2-mL fluid bolus were recorded with an oesophageal catheter, and gastric emptying was determined via the fluid volume recovered from the stomach 30-min post-bolus. Experiments involving acute nerve transections or pharmacological blockade of nitric oxide synthesis revealed that the initial increase of IGP after a 0.35 mol L(-1) HCl bolus is dampened by duodenogastric and gastrogastric relaxation reflexes depending on vagal and splanchnic pathways as well as nitric oxide. Compared with saline, HCl (0.15-0.5 mol L(-1)) delayed the subsequent decrease (adaptation) of IGP, inhibited gastric emptying and stimulated gastric fluid secretion as seen in stomachs with ligated pylorus. The acid-evoked delay in IGP adaptation and inhibition of gastric emptying involved duodenogastric and duodenopyloric extrinsic nerve reflexes, whereas the gastric fluid secretion was independent of the extrinsic innervation. It is proposed that the gastropyloric motor changes induced by luminal acid challenge have a bearing on the motor disturbances underlying functional dyspepsia.
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Affiliation(s)
- P Holzer
- Department of Experimental and Clinical Pharmacology, University of Graz, Graz, Austria.
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38
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Berthoud HR, Hennig G, Campbell M, Volaufova J, Costa M. Video-based spatio-temporal maps for analysis of gastric motility in vitro: effects of vagal stimulation in guinea-pigs. Neurogastroenterol Motil 2002; 14:677-88. [PMID: 12464090 DOI: 10.1046/j.1365-2982.2002.00369.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Our aim was to evaluate topographically specific gastric motility changes induced by graded vagal activation. A recently developed method of constructing spatio-temporal maps of motility from video movies was adapted to the in vitro perfused guinea-pig stomach with an intact vagal nerve supply. In the unstimulated preparation, spontaneous activity was low or absent. Bilateral vagal stimulation with frequencies as low as 0.2 Hz triggered weak anally, and in some cases orally, propagating antral contractions at rates of about 5-6 min-1. Upon stimulation with higher frequencies, antral contractions increased significantly in length (starting more proximally) and amplitude, and produced large pressure peaks of up to 25 hPa, with maximal effects at 2-4 Hz. In contrast, the speed of propagation and the interval between peristaltic waves did not change with vagal stimulation at any frequency. Vagal stimulation also produced a significant and frequency-dependent enlargement of the fundus with a maximal effect at 4 Hz. It is concluded that a very low tonic vagal activity is apparently necessary and sufficient to express basic antral motility, while more sustained vagal activity is necessary for high-amplitude gastric contractions and significant sustained fundic relaxation. The constant interval between propagating contractions supports the concept that vagal input impinges on intrinsic enteric neural circuits that have a modulatory role in the myogenic mechanism underlying slow-wave peristalsis, rather than directly on gastric musculature.
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Affiliation(s)
- H-R Berthoud
- Neurobiology of Nutrition Laboratory, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge 70808, USA.
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39
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Pfannkuche H, Reiche D, Hoppe S, Schemann M. Cholinergic and noncholinergic innervation of the smooth muscle layers in the bovine abomasum. THE ANATOMICAL RECORD 2002; 267:70-7. [PMID: 11984794 DOI: 10.1002/ar.10087] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The intrinsic innervation of muscle layers in the mammalian gastrointestinal tract has been mainly studied in nonruminants. The aim of this study was to identify intrinsic motor neurones in the bovine abomasum that innervate the circular and longitudinal muscles. Circular (CMN) and longitudinal muscle motor neurones (LMN) were selectively labeled by application of the retrograde tracer 1,1'-didodecyl-3,3,3',3'-tetramethyl indocarbocyanine perchlorate (DiI) onto the muscle layers. The transmitter phenotype was determined by immunohistochemical detection of choline acetyltransferase (ChAT), nitric oxide synthase (NOS), and neurone-specific enolase (NSE). On average, the myenteric ganglia contained 61 +/- 19 NSE-positive cell bodies, of which 89% were ChAT-positive and 10% were NOS-positive. Only 0.7% of NSE-positive neurones (41 of 5,777) contained both ChAT and NOS. Application of DiI onto the circular and longitudinal muscles revealed on average 60 +/- 27 (n = 4) and 68 +/- 36 (n = 4), respectively, labeled cell bodies in the myenteric plexus. For the circular and longitudinal muscles the proportions of ascending to descending neurones were 76 : 24% and 54 : 46%, respectively. While most ascending CMN were ChAT-positive (96%), 51% of the descending CMN were ChAT-negative. All ascending and 95% of descending LMN were ChAT-positive. It was concluded that cholinergic excitatory innervation is predominant in both muscle layers of the abomasum. Whereas the circular muscle receives cholinergic excitatory and nitrergic inhibitory innervation, the longitudinal muscle is only innervated by cholinergic pathways. This innervation pattern is different from that in gastric muscle layers in monogastric animals.
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Affiliation(s)
- Helga Pfannkuche
- Veterinär-Physiologisches Institut, Veterinärmedizinische Fakultät, Universität Leipzig, Leipzig, Germany.
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Rao SSC, Vemuri S, Harris B, Schulze K. Fundic balloon distension stimulates antral and duodenal motility in man. Dig Dis Sci 2002; 47:1015-9. [PMID: 12018896 DOI: 10.1023/a:1015077721427] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Distension of the intestine triggers the peristaltic reflex, which consists of orad contraction and aborad relaxation. Whether a similar response occurs in the human stomach is unclear. Our aim was to investigate the antral and duodenal motor response(s) to mechanical distension of the proximal stomach. In six healthy volunteers, a large compliant balloon was placed in the proximal stomach. Alongside this a water-perfused manometry probe with six sensors was placed to measure the antral and duodenal motility. Pressure activity was assessed before and during balloon distension. In five of six subjects, balloon distension triggered a salvo of antral pressure waves within 3-5 min, some of which propagated into the duodenum. The amplitude of waves was higher (P < 0.05) at the antrum than at the duodenum. The area under the curve of pressure waves was higher (P < 0.05) at the antrum than at the duodenum. In conclusion, distension of the proximal stomach, at or below the threshold for perception, evokes phasic motor activity in the antrum and duodenum. Thus, the gastric response to distension differs from that observed during the intestinal peristaltic reflex.
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Affiliation(s)
- Satish S C Rao
- Department of Medicine, University of Iowa College of Medicine, Iowa City, USA
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Yoneda S, Suzuki H. Nitric oxide inhibits smooth muscle responses evoked by cholinergic nerve stimulation in the guinea pig gastric fundus. THE JAPANESE JOURNAL OF PHYSIOLOGY 2001; 51:693-702. [PMID: 11846960 DOI: 10.2170/jjphysiol.51.693] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
In circular smooth muscle tissues of the guinea pig gastric fundus, transmural nerve stimulation (TNS) evoked an atropine-sensitive cholinergic excitatory junction potential (e.j.p.) and, after inhibiting the e.j.p. with atropine, an apamin-sensitive nonadrenergic noncholinergic (NANC) inhibitory junction potential (i.j.p.). The amplitude of e.j.p.s was similar when the frequency of TNS was low (<0.5 Hz), but it decreased successively (depression phenomenon) when the frequency was high (>1 Hz). The depression phenomenon was attenuated after inhibiting the production of nitric oxide (NO) with N(omega)-nitro-L-arginine (NOLA), but was not altered by inhibiting the i.j.p. with apamin. The e.j.p.s were increased in amplitude by the inhibition of cholinesterase activity, but they were decreased by NO produced from SNP with no alteration of their depression phenomenon. Isometric twitch contractions were depressed during high-frequency TNS. NOLA caused an increase in the amplitude of twitch contractions and the attenuation of their depression that changed the transient contraction produced by high-frequency TNS (1 Hz) to a tetanic one. SNP reduced the amplitude of twitch contractions, with no alteration of the depression phenomena. Contractions produced by low concentrations of acetylcholine, but not by high concentrations, were attenuated by SNP, with no alteration of the membrane depolarization. The results suggest that NO produced during TNS has inhibitory actions on cholinergic transmission; the depression of e.j.p.s is mainly prejunctional events, and the depression of mechanical responses is mainly postjunctional events.
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Affiliation(s)
- S Yoneda
- Department of Physiology, Nagoya City University Medical School, Nagoya, 467-8601 Japan
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Yoneda S, Kito Y, Suzuki H. Inhibitory actions of indomethacin on electrical and mechanical responses produced by nerve stimulation in circular smooth muscle of the guinea-pig gastric fundus. J Smooth Muscle Res 2001; 37:81-93. [PMID: 11885749 DOI: 10.1540/jsmr.37.81] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The effects of indomethacin on electrical and mechanical responses produced by transmural nerve stimulation (TNS) were investigated in isolated circular smooth muscle of the guinea-pig gastric fundus. TNS evoked a cholinergic excitatory junction potential (e.j.p.). The e.j.p.s were inhibited by 1-10 microM indomethacin, in a concentration-dependent manner, with no marked alteration of the resting membrane potential. Exogenously applied acetylcholine caused a depolarization of the membrane that was not altered by indomethacin. TNS evoked a cholinergic twitch contraction at low frequencies (0.1 Hz). A train of TNS's at high frequency (1 Hz) produced a transient contraction with a subsequent sustained relaxation. Indomethacin reduced the resting tension and inhibited these TNS-induced contractions. Application of Nomega-nitro-L-arginine (NOLA), an inhibitor of nitric oxide (NO) synthesis, increased the amplitude of twitch contractions, and altered transient contractions to tetanic contractions during TNS at a frequency of 1 Hz, also with an increased amplitude. In the presence of NOLA, indomethacin (5 microM) again reduced the resting tension and inhibited TNS-induced contractions. This inhibition was greater for twitch contractions than for tetanic contractions. Nifedipine reduced the TNS-induced contractions, while addition of indomethacin further reduced the amplitude of contractions. Contractions produced by low concentrations of acetylcholine (0.1 microM) were inhibited by indomethacin, while those produced by 1 microM were not. These results indicate that the inhibitory actions of indomethacin on TNS-induced contractions do not involve enhanced production of NO or selective inhibition of voltage-gated Ca-channels. Prejunctional autoregulatory mechanisms may also not be altered by indomethacin. As indomethacin inhibits the enzyme cyclooxygenase, it is speculated that endogenously produced prostaglandins exert excitatory actions on gastric smooth muscle, and act mainly postjunctionally to facilitate spontaneous and neurogenic electrical and mechanical activity.
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Affiliation(s)
- S Yoneda
- Department of Physiology, Nagoya City University Medical School, Nagoya, Japan
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Zagorodnyuk VP, Chen BN, Brookes SJ. Intraganglionic laminar endings are mechano-transduction sites of vagal tension receptors in the guinea-pig stomach. J Physiol 2001; 534:255-68. [PMID: 11433006 PMCID: PMC2278677 DOI: 10.1111/j.1469-7793.2001.00255.x] [Citation(s) in RCA: 194] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
1. Distension-sensitive vagal afferent fibres from the cardiac region of the guinea-pig stomach were recorded extracellularly, then filled with biotinamide, using an anterograde tracing technique. 2. Most of the stretch-sensitive units of the guinea-pig stomach (41 out of 47; number of animals N = 26) had low thresholds (less than 1 mm) to circumferential stretch and showed slow adaptation. Twenty of these units fired spontaneously under resting conditions (mean: 1.9 +/- 0.3 Hz, n = 20, N = 14). 3. Adaptation of firing during slow or maintained stretch correlated closely with accommodation of intramural tension, but tension-independent adaptation was also present. 4. Nicardipine (3 microM) with hyoscine (3 microM) reduced stretch-evoked firing of gastric vagal afferents, by inhibiting smooth muscle contraction. Gadolinium (1 mM) blocked distension-evoked firing. 5. Focal stimulation of the stomach muscle wall with a von Frey hair (0.4 mN) identified one to six punctate receptive fields in each low threshold vagal distension-sensitive afferent. These were marked on the serosal surface of the stomach wall. 6. Anterograde filling of recorded nerve trunks revealed intraganglionic laminar endings (IGLEs) within 142 +/- 34 microm (n = 38; N = 10) of marked receptive fields. The mean distance from randomly generated sites to the nearest IGLE was significantly greater (1500 +/- 48 microm, n = 380, N = 10, P < 0.0001). Viscerofugal nerve cell bodies, intramuscular arrays and varicose axons were not associated with receptive fields. The results indicate that IGLEs are the mechanotransduction sites of low threshold, slowly adapting vagal tension receptors in the guinea-pig upper stomach.
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Affiliation(s)
- V P Zagorodnyuk
- Department of Human Physiology and Centre for Neuroscience, Flinders University of South Australia, GPO Box 2100, Adelaide, South Australia.
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Abstract
Gut motility in non-mammalian vertebrates as in mammals is controlled by the presence of food, by autonomic nerves and by hormones. Feeding and the presence of food initiates contractions of the stomach wall and subsequently gastric emptying, peristalsis, migrating motor complexes and other patterns of motility follow. This overview will give examples of similarities and differences in control systems between species. Gastric receptive relaxation occurs in fish and is an enteric reflex. Cholecystokinin reduces the rate of gastric emptying in fish as in mammals. Inhibitory control of peristalsis is exerted, e.g. by VIP, PACAP, NO in fish and amphibians, while excitatory stimuli arise from nerves releasing tachykinins, acetylcholine or serotonin (5-HT). In crocodiles, we have found the presence of the same nerve types, although the effects on peristalsis have not been studied. Recent studies on signal transduction in the gut smooth muscle of fish and amphibians suggest that external Ca2+ is of great importance, but not the only source of Ca2+ recruitment in tachykinin-, acetylcholine- or serotonin-induced contractions of rainbow trout and Xenopus gastrointestinal smooth muscle. The effect of acetylcholine involves reduction of cAMP-levels in the smooth muscle cells. It is concluded that, in general, the control systems in non-mammalian vertebrates are amazingly similar between species and animal groups and in comparison with mammals.
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Affiliation(s)
- C Olsson
- Department of Zoophysiology, University of Göteborg, Box 463, SE 405 30, Göteborg, Sweden
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Abstract
Neuroanatomical tracing techniques, and retrograde labelling in particular, are widely used tools for the analysis of neuronal pathways in the central and peripheral nervous system. Over the last 10 years, these techniques have been used extensively to identify enteric neuronal pathways. In combination with multiple-labelling immunohistochemistry, quantitative data about the projections and neurochemical profile of many functional classes of cells have been acquired. These data have revealed a high degree of organization of the neuronal plexuses, even though the different classes of nerve cell bodies appear to be randomly assorted in ganglia. Each class of neurone has a predictable target, length and polarity of axonal projection, a particular combination of neurochemicals in its cell body and distinctive morphological characteristics. The combination of retrograde labelling with targeted intracellular recording has made it possible to target small populations of cells that would rarely be sampled during random impalements. These neuroanatomical techniques have also been applied successfully to human tissue and are gradually unravelling the complexity of the human enteric nervous system.
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Affiliation(s)
- S Brookes
- Department of Human Physiology and Centre for Neuroscience, Flinders University, South Australia.
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Abstract
This report summarises the characteristics of target specific projection and neurochemical coding patterns of motor and interneuronal pathways in the gastric enteric nervous system (ENS) which are involved in the innervation of the mucosa, the circular and the longitudinal muscle. The pathways were identified by retrograde tracing and further characterised by optical and intracellular recordings of the synaptic activation of muscle motor neurones, and by recordings of pathway-specific muscle responses. All motor pathways had polarised projections consisting of ascending cholinergic and descending nitrergic populations. Thus, both muscle layers were innervated by excitatory and inhibitory motor neurones. Their projections indicated the presence of intrinsic circuits that mediate excitatory and inhibitory components of a peristaltic reflex and/or are involved in reflex mediated changes in gastric tone. Although polarised projections were also identified for interneuronal pathways, a substantial proportion of descending interneurones was cholinergic. Interneurones and longitudinal muscle motor pathways had longitudinal projection preferences whereas circular muscle motor pathways had circumferential projection preferences. Target-specific coding was primarily revealed for cholinergic populations; ChAT/ENK/+/-SP neurones projected to the muscle layers, ChAT/NPY/+/-VIP projected to the mucosa and ChAT/+/-SP/+/-5-HT/+/-Calret/+/-Calb were interneurones. Muscle strip recordings revealed the functional significance of ascending excitatory and descending inhibitory pathways to the circular muscle and the prominent influence of ascending and descending cholinergic interneurones which activated excitatory and inhibitory circular muscle motor neurones through nicotinic synapses. It is concluded that enteric pathways in the stomach have region specific features which reflect structural and functional adaptation of the gastric ENS.
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Affiliation(s)
- M Schemann
- Department of Physiology, School of Veterinary Medicine, D-30173 Hannover, Germany.
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Abstract
The gastric sling (oblique) muscle (GSM), located close to the lower esophageal sphincter (LES), is involved in gastric motor function and may cooperate with the LES in controlling propulsion between the esophagus and stomach. Neuronal pathways and transmission to the GSM were investigated in isolated esophagus-stomach preparations by using intracellular recording with the focal electrical stimulation and neuroanatomical tracing method. Focal stimulation on the GSM evoked inhibitory junction potentials (IJPs) that were reduced to 45% by 100 microM N-nitro-L-arginine and subsequently blocked by 0.5 microM apamin, thereby unmasking excitatory junction potentials (EJPs), which were abolished by 1 microM hyoscine. Vagal and esophageal stimulation evoked IJPs that were blocked by 100 microM hexamethonium. Vagal stimulation also evoked EJPs after blockade of IJPs. Application of 1,1'-didodecyl-3,3,3',3'-tetramethyl indocarbocyanine perchlorate to the GSM labeled muscle motor neurons located in the stomach mainly close to the GSM, with a few neurons (2%) in the esophagus. The majority (79%) of labeled neurons were immunoreactive for choline acetyltransferase and, hence, excitatory motor neurons. Inhibitory motor neurons (nitric oxide synthase immunoreactive; 15%) were clustered in the midline near the gastroesophageal region. These results demonstrate that the GSM is innervated primarily by gastric excitatory and inhibitory motor neurons and some esophageal neurons. Both excitatory (acetylcholine) and inhibitory (nitric oxide and apamin-sensitive component) transmission can be activated via vagal-enteric pathways.
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Affiliation(s)
- S Yuan
- Department of Human Physiology and Centre for Neuroscience, Flinders University, Adelaide, South Australia 5100, Australia.
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Geishauser T, Reiche D, Schemann M. In vitro motility disorders associated with displaced abomasum in dairy cows. Neurogastroenterol Motil 1998; 10:395-401. [PMID: 9805315 DOI: 10.1046/j.1365-2982.1998.00119.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The objective of this study was to investigate in vitro abomasal motility in dairy cows diagnosed with displaced abomasum. Longitudinal muscle myenteric plexus preparations originating from the abomasal antrum of control cows, and cows diagnosed with left displaced abomasum (LDA), right displaced abomasum (RDA) or abomasal volvulus (AV) were used. In control preparations electrical field stimulation evoked an immediate cholinergic contractile response exceeding amplitude of basal contractions by 60%. In contrast, contractile activity was significantly inhibited during electrical stimulation in LDA, RDA and AV by 47%, 66% and 45%, respectively. This inhibition was reversed in the presence of L-NAME. The staining intensity of NADPH-positive myenteric neurones was significantly higher in displaced abomasa than in controls. Concentration-response curves indicated that preparations from displaced abomasa showed reduced sensitivity to acetylcholine. This study demonstrated motility disorders in displaced abomasa in vitro. The results suggested that abomasal displacement is associated with malfunctions at the level of the intrinsic nervous system combined with impaired cholinergic muscle responses. There appeared to be a predominance of nitrergic inhibitory mechanisms over excitatory mechanisms. These results might be of significance for diseases associated with gastric hypomotility and emptying disorders.
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Affiliation(s)
- T Geishauser
- Medical and Forensic Veterinary Clinic II (Internal Diseases of Ruminants), Justus-Liebig-University, Giessen, Germany
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Abstract
The projections of enteric neurons to the circular muscle of the guinea pig gastric corpus were investigated systematically by using the retrogradely transported fluorescent carbocyanine dye 1,1'-didodecyl-3,3,3',3'-tetramethyl indocarbocyanine perchlorate (DiI), applied to the muscle layer or myenteric plexus in vitro. DiI-labeled motor neuron cell bodies were located up to 6.3 mm aboral, 17 mm oral, and up to 20 mm circumferential to the DiI application site. Labeled nerve fibers ran for long distances from the DiI application site toward the greater and lesser curvatures, where they coursed parallel to the bundles of the "gastric sling" muscle. The majority of labeled cells were located toward the lesser curvature of the stomach. Nerve cell bodies that were aboral to the DiI application site were usually small, immunoreactive for choline acetyltransferase, and, thus, were likely to be excitatory motor neurons. Neurons that were located orally were larger, fewer in number, and immunoreactive for nitric oxide synthase and, thus, were likely to be inhibitory motor neurons. Application of DiI directly to the myenteric plexus filled neurons up to 15 mm aborally and up to 21 mm orally but labeled few neurons circumferentially. All nerve cells that were filled from either the circular muscle or the myenteric plexus had Dogiel type I morphological features. These results demonstrate a clear polarity of projection of inhibitory and excitatory motor neurons and a functionally continuous innervation of the circular and gastric sling muscle layers. Nonmotor neurons in the myenteric plexus were demonstrated, but neurons with Dogiel type II morphological features are apparently absent.
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Affiliation(s)
- S J Brookes
- Department of Human Physiology, Flinders University, Adelaide, South Australia.
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