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Sanders KM, Mutafova-Yambolieva VN. Neurotransmitters responsible for purinergic motor neurotransmission and regulation of GI motility. Auton Neurosci 2021; 234:102829. [PMID: 34146957 DOI: 10.1016/j.autneu.2021.102829] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 05/25/2021] [Accepted: 05/28/2021] [Indexed: 12/17/2022]
Abstract
Classical concepts of peripheral neurotransmission were insufficient to explain enteric inhibitory neurotransmission. Geoffrey Burnstock and colleagues developed the idea that ATP or a related purine satisfies the criteria for a neurotransmitter and serves as an enteric inhibitory neurotransmitter in GI muscles. Cloning of purinergic receptors and development of specific drugs and transgenic mice have shown that enteric inhibitory responses depend upon P2Y1 receptors in post-junctional cells. The post-junctional cells that transduce purinergic neurotransmitters in the GI tract are PDGFRα+ cells and not smooth muscle cells (SMCs). PDGFRα+ cells express P2Y1 receptors, are activated by enteric inhibitory nerve stimulation and generate Ca2+ oscillations, express small-conductance Ca2+-activated K+ channels (SK3), and generate outward currents when exposed to P2Y1 agonists. These properties are consistent with post-junctional purinergic responses, and similar responses and effectors are not functional in SMCs. Refinements in methodologies to measure purines in tissue superfusates, such as high-performance liquid chromatography (HPLC) coupled with etheno-derivatization of purines and fluorescence detection, revealed that multiple purines are released during stimulation of intrinsic nerves. β-NAD+ and other purines, better satisfy criteria for the purinergic neurotransmitter than ATP. HPLC has also allowed better detection of purine metabolites, and coupled with isolation of specific types of post-junctional cells, has provided new concepts about deactivation of purine neurotransmitters. In spite of steady progress, many unknowns about purinergic neurotransmission remain and require additional investigation to understand this important regulatory mechanism in GI motility.
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Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada, School of Medicine, 1664 North Virginia Street, Reno, NV 89557, USA.
| | - Violeta N Mutafova-Yambolieva
- Department of Physiology and Cell Biology, University of Nevada, School of Medicine, 1664 North Virginia Street, Reno, NV 89557, USA
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Enteric nervous system: sensory transduction, neural circuits and gastrointestinal motility. Nat Rev Gastroenterol Hepatol 2020; 17:338-351. [PMID: 32152479 PMCID: PMC7474470 DOI: 10.1038/s41575-020-0271-2] [Citation(s) in RCA: 266] [Impact Index Per Article: 66.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/27/2020] [Indexed: 02/07/2023]
Abstract
The gastrointestinal tract is the only internal organ to have evolved with its own independent nervous system, known as the enteric nervous system (ENS). This Review provides an update on advances that have been made in our understanding of how neurons within the ENS coordinate sensory and motor functions. Understanding this function is critical for determining how deficits in neurogenic motor patterns arise. Knowledge of how distension or chemical stimulation of the bowel evokes sensory responses in the ENS and central nervous system have progressed, including critical elements that underlie the mechanotransduction of distension-evoked colonic peristalsis. Contrary to original thought, evidence suggests that mucosal serotonin is not required for peristalsis or colonic migrating motor complexes, although it can modulate their characteristics. Chemosensory stimuli applied to the lumen can release substances from enteroendocrine cells, which could subsequently modulate ENS activity. Advances have been made in optogenetic technologies, such that specific neurochemical classes of enteric neurons can be stimulated. A major focus of this Review will be the latest advances in our understanding of how intrinsic sensory neurons in the ENS detect and respond to sensory stimuli and how these mechanisms differ from extrinsic sensory nerve endings in the gut that underlie the gut-brain axis.
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Diadenosine tetraphosphate activates P2Y 1 receptors that cause smooth muscle relaxation in the mouse colon. Eur J Pharmacol 2019; 855:160-166. [PMID: 31063775 DOI: 10.1016/j.ejphar.2019.05.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 05/03/2019] [Accepted: 05/03/2019] [Indexed: 01/01/2023]
Abstract
P2Y1 receptors play an essential role in inhibitory neuromuscular transmission in the gastrointestinal tract. The signalling pathway involves the opening of small conductance calcium activated potassium-channels (Kca2 family) that results in smooth muscle hyperpolarization and relaxation. Inorganic polyphosphates and dinucleotidic polyphosphates are putative neurotransmitters that potentially act on P2Y1 receptors. A pharmacological approach using both orthosteric (MRS2500) and allosteric (BPTU) blockers of the P2Y1 receptor and openers (CyPPA) and blockers (apamin) of Kca2 channels was used to pharmacologically characterise the effect of these neurotransmitters. Organ bath and microelectrodes were used to evaluate the effect of P1,P4-Di (adenosine-5') tetraphosphate ammonium salt (Ap4A), inorganic polyphosphates (PolyP) and CyPPA on spontaneous contractions and membrane potential of mouse colonic smooth muscle cells. PolyP neither modified contractions nor membrane potential. In contrast, Ap4A caused a concentration-dependent inhibition of spontaneous contractions reaching a maximum effect at 100 μM Ap4A response was antagonised by MRS2500 (1 μM), BPTU (3 μM) and apamin (1 μM). CyPPA (10 μM) inhibited spontaneous contractions and this response was antagonised by apamin but it was not affected by MRS2500 or BPTU. Both CyPPA and Ap4A caused smooth muscle hyperpolarization that was blocked by apamin and MRS2500 respectively. We conclude that Ap4A but not PolyP activates P2Y1 receptors causing smooth muscle hyperpolarization and relaxation. Ap4A signalling causes activation of Kca2 channels through activation of P2Y1 receptors. In contrast, CyPPA acts directly on Kca2 channels. Further studies are needed to evaluate if dinucleotidic polyphosphates are released from inhibitory motor neurons.
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Gallego D, Malagelada C, Accarino A, Gori A, Malagelada JR, Azpiroz F, De Giorgio R, Jimenez M. Functional neuromuscular impairment in severe intestinal dysmotility. Neurogastroenterol Motil 2018; 30:e13458. [PMID: 30178519 DOI: 10.1111/nmo.13458] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 07/18/2018] [Accepted: 08/06/2018] [Indexed: 12/12/2022]
Abstract
BACKGROUND Chronic intestinal pseudo-obstruction (CIPO) and enteric dysmotility (ED) are severe intestinal motility disorders usually associated with underlying neuromuscular abnormalities. OBJECTIVE To evaluate the in vitro neuromuscular function of patients with severe intestinal motility disorders. METHODS Full-thickness intestinal biopsies (16 jejunum and 3 ileum) obtained from patients with CIPO (n = 10) and ED (n = 9) were studied using muscle bath and microelectrode techniques. Control samples (n = 6 ileum and n = 6 jejunum) were used to establish the range of normality. KEY RESULTS Fourteen parameters were defined to assess muscle contractility and nerve-muscle interaction: five to evaluate smooth muscle and interstitial cells of Cajal (ICC) and nine to evaluate inhibitory neuromuscular transmission. For each sample, a parameter was scored 0 if the value was inside the normal range or a value of 1 if it was outside. Patients' samples (CIPO/ED) had more abnormal parameters than controls (P < 0.001 for both jejunum and ileum). Functional abnormalities were found to be heterogeneous. The most prevalent abnormality was a decreased purinergic neuromuscular transmission, which was detected in 43.8% of jejunal samples. CONCLUSIONS AND INFERENCES Abnormalities of neuromuscular intestinal function are detected in vitro in severe intestinal dysmotility. However, consistent with the heterogeneity of the disease pathophysiology, functional impairment cannot be attributed to a single mechanism. Specifically, defects of purinergic neuromuscular transmission may have an important role in motility disorders of the gastrointestinal tract.
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Affiliation(s)
- Diana Gallego
- Department of Cell Biology, Physiology and Immunology and Neurosciences Institute, Universitat Autònoma de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), Barcelona, Spain
| | - Carolina Malagelada
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), Barcelona, Spain.,Digestive System Research Unit, University Hospital Vall d'Hebron, Barcelona, Spain.,Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Anna Accarino
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), Barcelona, Spain.,Digestive System Research Unit, University Hospital Vall d'Hebron, Barcelona, Spain.,Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Alessandra Gori
- Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy
| | - Juan Ramón Malagelada
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), Barcelona, Spain.,Digestive System Research Unit, University Hospital Vall d'Hebron, Barcelona, Spain.,Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Fernando Azpiroz
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), Barcelona, Spain.,Digestive System Research Unit, University Hospital Vall d'Hebron, Barcelona, Spain.,Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain
| | | | - Marcel Jimenez
- Department of Cell Biology, Physiology and Immunology and Neurosciences Institute, Universitat Autònoma de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), Barcelona, Spain
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Kuzmin VS, Pustovit KB, Abramochkin DV. Effects of exogenous nicotinamide adenine dinucleotide (NAD+) in the rat heart are mediated by P2 purine receptors. J Biomed Sci 2016; 23:50. [PMID: 27350532 PMCID: PMC4924331 DOI: 10.1186/s12929-016-0267-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 06/17/2016] [Indexed: 12/13/2022] Open
Abstract
Background Recently, NAD+ has been considered as an essential factor, participating in nerve control of physiological functions and intercellular communication. NAD+ also has been supposed as endogenous activator of P1 and P2 purinoreceptors. Effects of extracellular NAD+ remain poorly investigated in cardiac tissue. This study aims to investigate the effects of extracellular NAD+ in different types of supraventricular and ventricular working myocardium from rat and their potential mechanisms. Methods The standard technique of sharp microelectrode action potential recording in cardiac multicellular preparations was used to study the effects of NAD+. Results Extracellular NAD+ induced significant changes in bioelectrical activity of left auricle (LA), right auricle (RA), pulmonary veins (PV) and right ventricular wall (RV) myocardial preparations. 10–100 μM NAD+ produced two opposite effects in LA and RA – quickly developing and transient prolongation of action potentials (AP) and delayed sustained AP shortening, which follows the initial positive effect. In PV and RV only AP shortening was observed in response to NAD+ application. In PV preparations AP shortening induced by NAD+ may be considered as a potential proarrhythmic effect. Revealed cardiotropic effects of NAD+ are likely to be mediated by P2 purine receptors, since P1 blocker DPCPX failed to affect them and P2 antagonist suramin abolished NAD + −induced alterations of electrical activity. P2X receptors may be responsible for NAD + −induced short-lasting AP prolongation, while P2Y receptors mediate persistent AP shortening. The latter effect is partially removed by PLC inhibitor U73122 showing the potential involvement of phosphoinositide signaling pathway in mediation of NAD+ cardiotropic effects. Conclusions Extracellular NAD+ is supposed to be a novel regulator of cardiac electrical activity. P2 receptors represent the main target of NAD+ at least in the rat heart.
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Affiliation(s)
- Vladislav S Kuzmin
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskie gory 1, building 12, Moscow, 119991, Russia.,Department of Physiology, Pirogov Russian National Research Medical University, Ostrovitjanova 1, Moscow, 117997, Russia
| | - Ksenia B Pustovit
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskie gory 1, building 12, Moscow, 119991, Russia.,Department of Physiology, Pirogov Russian National Research Medical University, Ostrovitjanova 1, Moscow, 117997, Russia
| | - Denis V Abramochkin
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskie gory 1, building 12, Moscow, 119991, Russia. .,Department of Physiology, Pirogov Russian National Research Medical University, Ostrovitjanova 1, Moscow, 117997, Russia.
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Gallego D, Mañé N, Gil V, Martínez-Cutillas M, Jiménez M. Mechanisms responsible for neuromuscular relaxation in the gastrointestinal tract. REVISTA ESPANOLA DE ENFERMEDADES DIGESTIVAS 2016; 108:721-731. [DOI: 10.17235/reed.2016.4058/2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Mañé N, Viais R, Martínez-Cutillas M, Gallego D, Correia-de-Sá P, Jiménez M. Inverse gradient of nitrergic and purinergic inhibitory cotransmission in the mouse colon. Acta Physiol (Oxf) 2016; 216:120-31. [PMID: 26347033 DOI: 10.1111/apha.12599] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 07/09/2015] [Accepted: 09/02/2015] [Indexed: 02/06/2023]
Abstract
AIM Gastrointestinal smooth muscle relaxation is accomplished by the neural corelease of ATP or a related purine and nitric oxide. Contractions are triggered by acetylcholine and tachykinins. The aim of this work was to study whether regional differences in neurotransmission could partially explain the varied physiological roles of each colonic area. METHODS We used electrophysiological and myography techniques to evaluate purinergic (L-NNA 1 mm incubated tissue), nitrergic (MRS2500 0.3 μm incubated tissue) and cholinergic neurotransmission (L-NNA 1 mm and MRS2500 0.3 μm incubated tissue) in the proximal, mid and distal colon of CD1 mice (n = 42). RESULTS Purinergic electrophysiological responses elicited by single pulses (28 V) were greater in the distal (IJPfMAX = -35.3 ± 2.2 mV), followed by the mid (IJPfMAX = -30.6 ± 1.0 mV) and proximal (IJPfMAX = -11.7 ± 1.1 mV) colon. In contrast, nitrergic responses decreased from the proximal colon (IJPsMAX = -11.4 ± 1.1 mV) to the mid (IJPsMAX = -9.1 ± 0.4 mV), followed by the distal colon (IJPsMAX = -1.8 ± 0.3 mV). A similar rank of order was observed in neural mediated inhibitory mechanical responses including electrical field stimulation-mediated responses and neural tone. ADPβs concentration-response curve was shifted to the left in the distal colon. In contrast, NaNP responses did not differ between regions. Cholinergic neurotransmission elicited contractions of a similar amplitude throughout the colon. CONCLUSION An inverse gradient of purinergic and nitrergic neurotransmission exists through the mouse colon. The proximal and mid colon have a predominant nitrergic neurotransmission probably due to the fact that their storage function requires sustained relaxations. The distal colon, in contrast, has mainly purinergic neurotransmission responsible for the phasic relaxations needed to propel dehydrated faeces.
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Affiliation(s)
- N. Mañé
- Department of Cell Biology, Physiology and Immunology and Neuroscience Institute; Universitat Autònoma de Barcelona; Barcelona Spain
| | - R. Viais
- Center for Drug Discovery and Innovative Medicines (MedInUP); Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto (ICBAS-UP); Porto Portugal
| | - M. Martínez-Cutillas
- Department of Cell Biology, Physiology and Immunology and Neuroscience Institute; Universitat Autònoma de Barcelona; Barcelona Spain
| | - D. Gallego
- Department of Cell Biology, Physiology and Immunology and Neuroscience Institute; Universitat Autònoma de Barcelona; Barcelona Spain
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd); Instituto de Salud Carlos III; Barcelona Spain
| | - P. Correia-de-Sá
- Center for Drug Discovery and Innovative Medicines (MedInUP); Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto (ICBAS-UP); Porto Portugal
| | - M. Jiménez
- Department of Cell Biology, Physiology and Immunology and Neuroscience Institute; Universitat Autònoma de Barcelona; Barcelona Spain
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd); Instituto de Salud Carlos III; Barcelona Spain
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Affiliation(s)
- Jackie D. Wood
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio
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Mutafova-Yambolieva VN, Sanders KM. Appropriate experimental approach is critical for identifying neurotransmitter substances: application to enteric purinergic neurotransmission. Am J Physiol Gastrointest Liver Physiol 2015; 309:G608-9. [PMID: 26429194 PMCID: PMC4593821 DOI: 10.1152/ajpgi.00225.2015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
| | - Kenton M. Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
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King BF. Purinergic signalling in the enteric nervous system (An overview of current perspectives). Auton Neurosci 2015; 191:141-7. [PMID: 26049261 DOI: 10.1016/j.autneu.2015.05.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Purinergic Signalling in the Enteric Nervous System involves the regulated release of ATP (or a structurally-related nucleotide) which activates an extensive suite of membrane-inserted receptors (P2X and P2Y subtypes) on a variety of cell types in the gastrointestinal tract. P2X receptors are gated ion-channels permeable to sodium, potassium and calcium. They depolarise cells, act as a pathway for calcium influx to activate calcium-dependent processes and initiate gene transcription, interact at a molecular level as a form of self-regulation with lipids within the cell wall (e.g. PIP2) and cross-react with other membrane-inserted receptors to regulate their activity (e.g. nAChRs). P2Y receptors are metabotropic receptors that couple to G-proteins. They may release calcium ions from intracellular stores to activate calcium-dependent processes, but also may activate calcium-independent signalling pathways and influence gene transcription. Originally ATP was a candidate only for NANC neurotransmission, for inhibitory motoneurons supplying the muscularis externa of the gastrointestinal tract and bringing about the fast IJP. Purinergic signalling later included neuron-neuron signalling in the ENS, via the production of either fast or slow EPSPs. Later still, purinergic signalling included the neuro-epithelial synapse-for efferent signalling to epithelia cells participating in secretion and absorption, and afferent signalling for chemoreception and mechanoreception at the surface of the mucosa. Many aspects of purinergic signalling have since been addressed in a series of highly-focussed and authoritative reviews. In this overview however, the current focus is on key aspects of purinergic signalling where there remains uncertainty and ambiguity, with the view to stimulating further research in these areas.
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Affiliation(s)
- Brian F King
- University College London (UCL), Department of Neuroscience, Physiology and Pharmacology (NPP), Royal Free Campus, Rowland Hill Street, Hampstead, London NW3 2PF, United Kingdom.
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