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Moriyama Y, Hasuzawa N, Nomura M. María Teresa Miras Portugal: a pioneer for vesicular nucleotide storage. Purinergic Signal 2024; 20:93-98. [PMID: 36525101 PMCID: PMC10997567 DOI: 10.1007/s11302-022-09912-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 12/05/2022] [Indexed: 12/23/2022] Open
Abstract
Chromaffin granules are secretory granules present in adrenal medulla chromaffin cells. They contain high contents of catecholamines and nucleotides and have been regarded as a model system for the study of vesicular transmitter uptake and release. In 1988, Dr. María Teresa Miras Portugal, when studying catecholamine biosynthesis, detected a novel group of nucleotides, the diadenosine polyphosphates, in the adrenal chromaffin granules. Based on this finding, she unraveled the existence of diadenosine polyphosphate-mediated chemical transmission, leading to a paradigm shift in the field of purinergic signaling. She is also a pioneer in the studies on vesicular nucleotide storage. First, María Teresa and her group characterized nucleotide transport in chromaffin granules and synaptic vesicles using fluorescent nucleotide derivatives such as 1, N6-ethenoadenosine triphosphates. Then, they revealed the presence of a hypothetical vesicular nucleotide transporter with unique properties in terms of substrate specificity. In this article, we will describe her contributions to vesicular nucleotide storage and the foundations she laid for future studies.
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Affiliation(s)
- Yoshinori Moriyama
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011, Japan.
| | - Nao Hasuzawa
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011, Japan
| | - Masatoshi Nomura
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011, Japan
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Babou Kammoe RB, Sévigny J. Extracellular nucleotides in smooth muscle contraction. Biochem Pharmacol 2024; 220:116005. [PMID: 38142836 DOI: 10.1016/j.bcp.2023.116005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 12/18/2023] [Accepted: 12/19/2023] [Indexed: 12/26/2023]
Abstract
Extracellular nucleotides and nucleosides are crucial signalling molecules, eliciting diverse biological responses in almost all organs and tissues. These molecules exert their effects by activating specific nucleotide receptors, which are finely regulated by ectonucleotidases that break down their ligands. In this comprehensive review, we aim to elucidate the relevance of extracellular nucleotides as signalling molecules in the context of smooth muscle contraction, considering the modulatory influence of ectonucleotidases on this intricate process. Specifically, we provide a detailed examination of the involvement of extracellular nucleotides in the contraction of non-vascular smooth muscles, including those found in the urinary bladder, the airways, the reproductive system, and the gastrointestinal tract. Furthermore, we present a broader overview of the role of extracellular nucleotides in vascular smooth muscle contraction.
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Affiliation(s)
- Romuald Brice Babou Kammoe
- Centre de Recherche du CHU de Québec - Université Laval, Québec City, QC G1V 4G2, Canada; Département de microbiologie-infectiologie et d'immunologie, Faculté de Médecine, Université Laval, Québec City, QC G1V 0A6, Canada
| | - Jean Sévigny
- Centre de Recherche du CHU de Québec - Université Laval, Québec City, QC G1V 4G2, Canada; Département de microbiologie-infectiologie et d'immunologie, Faculté de Médecine, Université Laval, Québec City, QC G1V 0A6, Canada.
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Waclawiková B, Codutti A, Alim K, El Aidy S. Gut microbiota-motility interregulation: insights from in vivo, ex vivo and in silico studies. Gut Microbes 2022; 14:1997296. [PMID: 34978524 PMCID: PMC8741295 DOI: 10.1080/19490976.2021.1997296] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 09/30/2021] [Accepted: 10/19/2021] [Indexed: 02/06/2023] Open
Abstract
The human gastrointestinal tract is home to trillions of microbes. Gut microbial communities have a significant regulatory role in the intestinal physiology, such as gut motility. Microbial effect on gut motility is often evoked by bioactive molecules from various sources, including microbial break down of carbohydrates, fibers or proteins. In turn, gut motility regulates the colonization within the microbial ecosystem. However, the underlying mechanisms of such regulation remain obscure. Deciphering the inter-regulatory mechanisms of the microbiota and bowel function is crucial for the prevention and treatment of gut dysmotility, a comorbidity associated with many diseases. In this review, we present an overview of the current knowledge on the impact of gut microbiota and its products on bowel motility. We discuss the currently available techniques employed to assess the changes in the intestinal motility. Further, we highlight the open challenges, and incorporate biophysical elements of microbes-motility interplay, in an attempt to lay the foundation for describing long-term impacts of microbial metabolite-induced changes in gut motility.
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Affiliation(s)
- Barbora Waclawiková
- Host-Microbe Interactions, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Groningen, The Netherlands
| | - Agnese Codutti
- Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany
| | - Karen Alim
- Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany
- Physics Department and Center for Protein Assemblies (CPA), Technische Universität München, Garching, Germany
| | - Sahar El Aidy
- Host-Microbe Interactions, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Groningen, The Netherlands
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Durnin L, Kurahashi M, Sanders KM, Mutafova-Yambolieva VN. Extracellular metabolism of the enteric inhibitory neurotransmitter β-nicotinamide adenine dinucleotide (β-NAD) in the murine colon. J Physiol 2020; 598:4509-4521. [PMID: 32735345 DOI: 10.1113/jp280051] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 07/20/2020] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS β-Nicotinamide adenine dinucleotide (β-NAD) is a key inhibitory neurotransmitter in the colon. The neuroeffector junction in the gut consists of enteric motor neurons and SIP syncytium, including smooth muscle cells (SMCs), interstitial cells of Cajal (ICC), and cells expressing platelet-derived growth factor receptor α (PDGFRα+ cells). Measuring metabolism of 1,N6 -etheno-NAD (eNAD) in colonic tunica muscularis and in SMCs, ICC and PDGFRα+ cells with HPLC-FLD, we report that (1) in tissues, eNAD is degraded to eADP-ribose, eAMP and e-adenosine (eADO) by CD38, ENPP1 and NT5E, (2) with SMCs and PDGFRα+ cells, eNAD is metabolized to eADO by ENPP1 and NT5E, (3) eNAD is not metabolized by ICC, (4) NT5E is expressed chiefly by SMCs and moderately by PDGFRα+ cells, (5) SIP cells are not the primary location of CD38. These data argue that the duration and strength of purinergic neurotransmission can be modulated by targeting multiple enzymes with specialized cellular distribution in the colon. ABSTRACT Prior studies suggest that β-nicotinamide adenine dinucleotide (β-NAD) is an important inhibitory motor neurotransmitter in the enteric nervous system. Metabolism of β-NAD at the neuroeffector junction (NEJ) is likely to be necessary for terminating inhibitory neurotransmission and may also produce bioactive metabolites. The enteric NEJ consists of enteric neurons and postjunctional cells of the SIP syncytium, including smooth muscle cells (SMCs), interstitial cells of Cajal (ICC), and cells expressing platelet-derived growth factor receptor α (PDGFRα+ cells). We examined possible specialized functions of the NEJ in β-NAD metabolism by determining the degradation of 1,N6 -etheno-NAD (eNAD) in colonic tunica muscularis of wild-type, Cd38-/- , Nt5e-/- , Enpp1-/- and Cd38-/- /Nt5e-/- mice and in SIP cells from mice expressing cell-specific fluorescent reporters purified by fluorescence activated cell sorting (FACS). We measured eNAD and its metabolites eADP-ribose (eADPR), eAMP and e-adenosine (eADO) from tissues and sorted SIP cells using liquid chromatography. eNAD exposed to colonic muscularis of wild-type mice produced eADPR, eAMP and eADO. CD38 mediated the conversion of eNAD to eADPR, whereas ENPP1 mediated degradation of eNAD and eADPR to eAMP. NT5E (aka CD73) was the primary enzyme forming eADO from eAMP. PDGFRα+ cells and SMCs were involved in production of eADO from eNAD, and ICC were not involved in extracellular metabolism of eNAD. CD38 mediated the eNAD metabolism in whole tissues, but CD38 did not appear to be functionally expressed by SMCs or ICC. NT5E was expressed in SMCs > PDGFRα+ cells. Our data show that extracellular metabolism of β-NAD in the colon is mediated by multiple enzymes with cell-specific expression.
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Affiliation(s)
- Leonie Durnin
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, 1664 North Virginia Street, Reno, NV, 89557, USA
| | - Masaaki Kurahashi
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, 1664 North Virginia Street, Reno, NV, 89557, USA
| | - 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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Perez-Medina AL, Galligan JJ. Optogenetic analysis of neuromuscular transmission in the colon of ChAT-ChR2-YFP BAC transgenic mice. Am J Physiol Gastrointest Liver Physiol 2019; 317:G569-G579. [PMID: 31411893 PMCID: PMC6879885 DOI: 10.1152/ajpgi.00089.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Propulsion of luminal content along the gut requires coordinated contractions and relaxations of gastrointestinal smooth muscles controlled by the enteric nervous system. Activation of excitatory motor neurons (EMNs) causes muscle contractions, whereas inhibitory motor neuron (IMN) activation causes muscle relaxation. EMNs release acetylcholine (ACh), which acts at muscarinic receptors on smooth muscle cells and adjacent interstitial cells of Cajal, causing excitatory junction potentials (EJPs). IMNs release ATP (or another purine) and nitric oxide to cause inhibitory junction potentials (IJPs) and muscle relaxation. We used commercially available choline acetyltransferase (ChAT)-channelrhodopsin-2 (ChR2)-yellow fluorescent protein (YFP) bacterial artificial chromosome (BAC) transgenic mice, which express ChR2 in cholinergic neurons, to study cholinergic neuromuscular transmission in the colon. Intracellular microelectrodes were used to record IJPs and EJPs from circular muscle cells. We used blue light stimulation (BLS, 470 nm, 20 mW/mm2) and electrical field stimulation (EFS) to activate myenteric neurons. EFS evoked IJPs only, whereas BLS evoked EJPs and IJPs. Mecamylamine (10 µM, nicotinic cholinergic receptor antagonist) reduced BLS-evoked IJPs by 50% but had no effect on electrically evoked IJPs. MRS 2179 (10 µM, a P2Y1 receptor antagonist) blocked BLS-evoked IJPs. MRS 2179 and Nω-nitro-l-arginine (100 µM, nitric oxide synthase inhibitor) isolated the EJP, which was blocked by scopolamine (1 µM, muscarinic ACh receptor antagonist). Immunohistochemistry revealed ChAT expression in ~88% of enhanced YFP (eYFP)-expressing neurons, whereas 12% of eYFP neurons expressed nitric oxide synthase. These data show that cholinergic interneurons synapse with EMNs and IMNs to cause contraction and relaxation of colonic smooth muscle.NEW & NOTEWORTHY Electrical stimulation of interganglionic connectives has been used widely to study synaptic transmission in the enteric nervous system. However, electrical stimulation will activate many types of neurons and nerve fibers, which complicates data interpretation. Optogenetic activation of enteric neurons using genetically modified mice expressing channelrhodopsin-2 in cholinergic neurons offers a new approach that provides more specificity for nerve stimulation when studying myenteric plexus nerve circuitry.
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Affiliation(s)
| | - James J. Galligan
- 1Department of Pharmacology & Toxicology, Michigan State University, East Lansing, Michigan,2Neuroscience Program, Michigan State University, East Lansing, Michigan
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Abstract
The gastrointestinal tract of vertebrates is a heterogeneous organ system innervated to varying degrees by a local enteric neural network as well as extrinsic parasympathetic and sympathetic neural circuits located along the brainstem and spinal axis. This diverse organ system serves to regulate the secretory and propulsive reflexes integral to the digestion and absorption of nutrients. The quasi-segmental distribution of the neural circuits innervating the gastrointestinal (GI) tract produces varying degrees of dysfunction depending upon the level of spinal cord injury (SCI). At all levels of SCI, GI dysfunction frequently presents life-long challenges to individuals coping with injury. Growing attention to the profound changes that occur across the entire physiology of individuals with SCI reveals profound knowledge gaps in our understanding of the temporal dimensions and magnitude of organ-specific co-morbidities following SCI. It is essential to understand and identify these broad pathophysiological changes in order to develop appropriate evidence-based strategies for management by clinicians, caregivers and individuals living with SCI. This review summarizes the neurophysiology of the GI tract in the uninjured state and the pathophysiology associated with the systemic effects of SCI.
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Affiliation(s)
- Gregory M Holmes
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA 17033, United states of America.
| | - Emily N Blanke
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA 17033, United states of America
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Vieira C, Ferreirinha F, Magalhães-Cardoso MT, Silva I, Marques P, Correia-de-Sá P. Post-inflammatory Ileitis Induces Non-neuronal Purinergic Signaling Adjustments of Cholinergic Neurotransmission in the Myenteric Plexus. Front Pharmacol 2017; 8:811. [PMID: 29167643 PMCID: PMC5682326 DOI: 10.3389/fphar.2017.00811] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 10/26/2017] [Indexed: 12/11/2022] Open
Abstract
Uncoupling between ATP overflow and extracellular adenosine formation changes purinergic signaling in post-inflammatory ileitis. Adenosine neuromodulation deficits were ascribed to feed-forward inhibition of ecto-5′-nucleotidase/CD73 by high extracellular adenine nucleotides in the inflamed ileum. Here, we hypothesized that inflammation-induced changes in cellular density may also account to unbalance the release of purines and their influence on [3H]acetylcholine release from longitudinal muscle-myenteric plexus preparations of the ileum of 2,4,6-trinitrobenzenesulfonic acid (TNBS)-treated rats. The population of S100β-positive glial cells increase, whereas Ano-1-positive interstitial cells of Cajal (ICCs) diminished, in the ileum 7-days after the inflammatory insult. In the absence of changes in the density of VAChT-positive cholinergic nerves detected by immunofluorescence confocal microscopy, the inflamed myenteric plexus released smaller amounts of [3H]acetylcholine which also became less sensitive to neuronal blockade by tetrodotoxin (1 μM). Instead, [3H]acetylcholine release was attenuated by sodium fluoroacetate (5 mM), carbenoxolone (10 μM) and A438079 (3 μM), which prevent activation of glial cells, pannexin-1 hemichannels and P2X7 receptors, respectively. Sodium fluoroacetate also decreased ATP overflow without significantly affecting the extracellular adenosine levels, thus indicating that surplus ATP release parallels reactive gliosis in post-inflammatory ileitis. Conversely, loss of ICCs may explain the lower amounts of adenosine detected in TNBS-treated preparations, since blockade of Cav3 (T-type) channels existing in ICCs with mibefradil (3 μM) or inhibition of the equilibrative nucleoside transporter 1 with dipyridamole (0.5 μM), both decreased extracellular adenosine. Data indicate that post-inflammatory ileitis operates a shift on purinergic neuromodulation reflecting the upregulation of ATP-releasing enteric glial cells and the depletion of ICCs accounting for decreased adenosine overflow via equilibrative nucleoside transporters.
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Affiliation(s)
- Cátia Vieira
- Laboratório de Farmacologia e Neurobiologia, Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Fátima Ferreirinha
- Laboratório de Farmacologia e Neurobiologia, Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Maria T Magalhães-Cardoso
- Laboratório de Farmacologia e Neurobiologia, Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Isabel Silva
- Laboratório de Farmacologia e Neurobiologia, Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Patrícia Marques
- Laboratório de Farmacologia e Neurobiologia, Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Paulo Correia-de-Sá
- Laboratório de Farmacologia e Neurobiologia, Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal
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Durnin L, Lees A, Manzoor S, Sasse KC, Sanders KM, Mutafova-Yambolieva VN. Loss of nitric oxide-mediated inhibition of purine neurotransmitter release in the colon in the absence of interstitial cells of Cajal. Am J Physiol Gastrointest Liver Physiol 2017; 313:G419-G433. [PMID: 28705804 PMCID: PMC5792210 DOI: 10.1152/ajpgi.00045.2017] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 06/26/2017] [Accepted: 07/11/2017] [Indexed: 01/31/2023]
Abstract
Regulation of colonic motility depends on the integrity of enteric inhibitory neurotransmission mediated by nitric oxide (NO), purine neurotransmitters, and neuropeptides. Intramuscular interstitial cells of Cajal (ICC-IM) and platelet-derived growth factor receptor-α-positive (PDGFRα+) cells are involved in generating responses to NO and purine neurotransmitters, respectively. Previous studies have suggested a decreased nitrergic and increased purinergic neurotransmission in KitW/KitW-v (W/Wv ) mice that display lesions in ICC-IM along the gastrointestinal tract. However, contributions of NO to these phenotypes have not been evaluated. We used small-chamber superfusion assays and HPLC to measure the spontaneous and electrical field stimulation (EFS)-evoked release of nicotinamide adenine dinucleotide (NAD+)/ADP-ribose, uridine adenosine tetraphosphate (Up4A), adenosine 5'-triphosphate (ATP), and metabolites from the tunica muscularis of human, monkey, and murine colons and circular muscle of monkey colon, and we tested drugs that modulate NO levels or blocked NO receptors. NO inhibited EFS-evoked release of purines in the colon via presynaptic neuromodulation. Colons from W/Wv, Nos1-/- , and Prkg1-/- mice displayed augmented neural release of purines that was likely due to altered nitrergic neuromodulation. Colons from W/Wv mice demonstrated decreased nitrergic and increased purinergic relaxations in response to nerve stimulation. W/Wv mouse colons demonstrated reduced Nos1 expression and reduced NO release. Our results suggest that enhanced purinergic neurotransmission may compensate for the loss of nitrergic neurotransmission in muscles with partial loss of ICC. The interactions between nitrergic and purinergic neurotransmission in the colon provide novel insight into the role of neurotransmitters and effector cells in the neural regulation of gastrointestinal motility.NEW & NOTEWORTHY This is the first study investigating the role of nitric oxide (NO) and intramuscular interstitial cells of Cajal (ICC-IM) in modulating neural release of purines in colon. We found that NO inhibited release of purines in human, monkey, and murine colons and that colons from KitW/KitW-v (W/Wv ) mice, which present with partial loss of ICC-IM, demonstrated augmented neural release of purines. Interactions between nitrergic and purinergic neurotransmission may affect motility in disease conditions with ICC-IM deficiencies.
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Affiliation(s)
- Leonie Durnin
- 1Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada; and
| | - Andrea Lees
- 1Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada; and
| | - Sheerien Manzoor
- 1Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada; and
| | | | - Kenton M. Sanders
- 1Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada; and
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Durnin L, Moreland N, Lees A, Mutafova-Yambolieva VN. A commonly used ecto-ATPase inhibitor, ARL-67156, blocks degradation of ADP more than the degradation of ATP in murine colon. Neurogastroenterol Motil 2016; 28:1370-81. [PMID: 27060478 PMCID: PMC5002237 DOI: 10.1111/nmo.12836] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 03/14/2016] [Indexed: 01/24/2023]
Abstract
BACKGROUND Adenosine 5'-triphosphate (ATP) is released extracellularly as a neurotransmitter and an autocrine or paracrine mediator in numerous systems, including the gastrointestinal tract. It is rapidly degraded to active and inactive metabolites by membrane-bound enzymes. Investigators frequently use inhibitors of ATP hydrolysis such as ARL-67156 and POM-1 to suppress the catabolism of ATP and prolong its effects in pharmacological studies. Our aim was to investigate directly the effects of ARL-67156 and POM-1 on the degradation of ATP and adenosine 5'-diphosphate (ADP) in mouse colonic muscles. METHODS The degradation of ATP and ADP was evaluated by superfusing tissues with 1,N(6) -etheno-ATP (eATP) and 1,N(6) -etheno-ADP (eADP) as substrates and monitoring the decrease in substrate and increase in products (i.e., eADP, eAMP, and e-adenosine) by high-performance liquid chromatography techniques with fluorescence detection. Relaxation responses to etheno-derivatized and non-derivatized ATP and ADP were examined in isometric tension experiments. KEY RESULTS ARL-67156 inhibits the degradation of ADP but not of ATP, whereas POM-1 inhibits the degradation of ATP but not of ADP in murine colonic muscles. Consequently, ARL-67156 enhances relaxation responses to both ATP and ADP, whereas POM-1 reduces relaxation to ATP and does not affect relaxation to ADP. CONCLUSIONS & INFERENCES Studies that use ARL-67156 to inhibit ATP degradation in smooth muscle likely evaluate responses to accumulated ADP rather than ATP. POM-1 appears to be a more selective inhibitor of ATP degradation in the mouse colon. The choice of pharmacological tools in studies on extracellular ATP signaling may affect the interpretation of experimental data in functional studies.
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Affiliation(s)
- L. Durnin
- Department of Physiology and Cell Biology; University of Nevada School of Medicine; Reno NV USA
| | - N. Moreland
- Department of Physiology and Cell Biology; University of Nevada School of Medicine; Reno NV USA
| | - A. Lees
- Department of Physiology and Cell Biology; University of Nevada School of Medicine; Reno NV USA
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Durnin L, Hayoz S, Corrigan RD, Yanez A, Koh SD, Mutafova-Yambolieva VN. Urothelial purine release during filling of murine and primate bladders. Am J Physiol Renal Physiol 2016; 311:F708-F716. [PMID: 27465992 DOI: 10.1152/ajprenal.00387.2016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 07/26/2016] [Indexed: 01/15/2023] Open
Abstract
During urinary bladder filling the bladder urothelium releases chemical mediators that in turn transmit information to the nervous and muscular systems to regulate sensory sensation and detrusor muscle activity. Defects in release of urothelial mediators may cause bladder dysfunctions that are characterized with aberrant bladder sensation during bladder filling. Previous studies have demonstrated release of ATP from the bladder urothelium during bladder filling, and ATP remains the most studied purine mediator that is released from the urothelium. However, the micturition cycle is likely regulated by multiple purine mediators, since various purine receptors are found present in many cell types in the bladder wall, including urothelial cells, afferent nerves, interstitial cells in lamina propria, and detrusor smooth muscle cells. Information about the release of other biologically active purines during bladder filling is still lacking. Decentralized bladders from C57BL/6 mice and Cynomolgus monkeys (Macaca fascicularis) were filled with physiological solution at different rates. Intraluminal fluid was analyzed by high-performance liquid chromatography with fluorescence detection for simultaneous evaluation of ATP, ADP, AMP, adenosine, nicotinamide adenine dinucleotide (NAD+), ADP-ribose, and cADP-ribose content. We also measured ex vivo bladder filling pressures and performed cystometry in conscious unrestrained mice at different filling rates. ATP, ADP, AMP, NAD+, ADPR, cADPR, and adenosine were detected released intravesically at different ratios during bladder filling. Purine release increased with increased volumes and rates of filling. Our results support the concept that multiple urothelium-derived purines likely contribute to the complex regulation of bladder sensation during bladder filling.
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Affiliation(s)
- Leonie Durnin
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Sebastien Hayoz
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Robert D Corrigan
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Andrew Yanez
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Sang Don Koh
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
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Abstract
The idea of an inhibitory innervation in the gut came from Geoff Burnstock's group at the University of Melbourne in the 1960s. Being resistant to antagonists of norepinephrine and acetylcholine, enteric inhibitory neurotransmission became known as non-cholinergic, non-adrenergic (NANC) neurotransmission. ATP (or a closely related nucleotide) was proposed as the inhibitory neurotransmitter based on release of purines during nerve stimulation and similarities between responses to ATP and transmural nerve stimulation in several gut preparations. Apamin was found to block purinergic responses, providing evidence that small-conductance Ca(2+)-activated K(+) (SK) channels were responsible for inhibitory junction potentials (IJPs). Actually the IJPs in GI muscles are composed of multiple components, and later studies discovered nitric oxide (NO) to be the other major mediator of NANC inhibitory neurotransmission. The purinergic component of enteric inhibitory neurotransmission is mediated by P2Y1 receptors, and this component is absent in P2Y1(-/-) mice. The criteria for a neurotransmitter are better met by β-nicotinamide adenine dinucleotide (β-NAD) or its immediate metabolite ADP-ribose (ADPR) than by ATP. The cells mediating post-junctional responses have been identified. In addition to smooth muscle cells, two classes of interstitial cells express receptors and effectors for NANC neurotransmitters and are electrically coupled to smooth muscle cells. This integrated structure has been named the SIP syncytium. Interstitial cells of Cajal are involved in transduction of cholinergic and nitrergic inputs to GI muscles, and PDGFRα(+) cells mediate purinergic effects. This short symposium report summarizes major historical points of interest and some of the more recent findings related to enteric inhibitory neurotransmission.
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Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, 89511, USA.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Wang GD, Wang XY, Liu S, Xia Y, Zou F, Qu M, Needleman BJ, Mikami DJ, Wood JD. β-Nicotinamide adenine dinucleotide acts at prejunctional adenosine A1 receptors to suppress inhibitory musculomotor neurotransmission in guinea pig colon and human jejunum. Am J Physiol Gastrointest Liver Physiol 2015; 308:G955-63. [PMID: 25813057 PMCID: PMC4451321 DOI: 10.1152/ajpgi.00430.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 03/18/2015] [Indexed: 01/31/2023]
Abstract
Intracellular microelectrodes were used to record neurogenic inhibitory junction potentials in the intestinal circular muscle coat. Electrical field stimulation was used to stimulate intramural neurons and evoke contraction of the smooth musculature. Exposure to β-nicotinamide adenine dinucleotide (β-NAD) did not alter smooth muscle membrane potential in guinea pig colon or human jejunum. ATP, ADP, β-NAD, and adenosine, as well as the purinergic P2Y1 receptor antagonists MRS 2179 and MRS 2500 and the adenosine A1 receptor agonist 2-chloro-N6-cyclopentyladenosine, each suppressed inhibitory junction potentials in guinea pig and human preparations. β-NAD suppressed contractile force of twitch-like contractions evoked by electrical field stimulation in guinea pig and human preparations. P2Y1 receptor antagonists did not reverse this action. Stimulation of adenosine A1 receptors with 2-chloro-N6-cyclopentyladenosine suppressed the force of twitch contractions evoked by electrical field stimulation in like manner to the action of β-NAD. Blockade of adenosine A1 receptors with 8-cyclopentyl-1,3-dipropylxanthine suppressed the inhibitory action of β-NAD on the force of electrically evoked contractions. The results do not support an inhibitory neurotransmitter role for β-NAD at intestinal neuromuscular junctions. The data suggest that β-NAD is a ligand for the adenosine A1 receptor subtype expressed by neurons in the enteric nervous system. The influence of β-NAD on intestinal motility emerges from adenosine A1 receptor-mediated suppression of neurotransmitter release at inhibitory neuromuscular junctions.
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Affiliation(s)
- Guo-Du Wang
- 1Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio;
| | - Xi-Yu Wang
- 1Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio;
| | - Sumei Liu
- 1Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio;
| | - Yun Xia
- 1Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio; ,2Department of Anesthesiology, College of Medicine, The Ohio State University, Columbus, Ohio; and
| | - Fei Zou
- 1Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio;
| | - Meihua Qu
- 1Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio;
| | - Bradley J. Needleman
- 3Department of Surgery, College of Medicine, The Ohio State University, Columbus, Ohio
| | - Dean J. Mikami
- 3Department of Surgery, College of Medicine, The Ohio State University, Columbus, Ohio
| | - Jackie D. Wood
- 1Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio;
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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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Abstract
The role of adenosine 5'-triphosphate (ATP) as a major intracellular energy source is well-established. In addition, ATP and related nucleotides have widespread extracellular actions via the ionotropic P2X (ligand-gated cation channels) and metabotropic P2Y (G protein-coupled) receptors. Numerous experimental techniques, including myography, electrophysiology and biochemical measurement of neurotransmitter release, have been used to show that ATP has several major roles as a neurotransmitter in peripheral nerves. When released from enteric nerves of the gastrointestinal tract it acts as an inhibitory neurotransmitter, mediating descending muscle relaxation during peristalsis. ATP is also an excitatory cotransmitter in autonomic nerves; 1) It is costored with noradrenaline in synaptic vesicles in postganglionic sympathetic nerves innervating smooth muscle preparations, such as the vas deferens and most arteries. When coreleased with noradrenaline, ATP acts at postjunctional P2X1 receptors to evoke depolarisation, Ca(2+) influx, Ca(2+) sensitisation and contraction. 2) ATP is also coreleased with acetylcholine from postganglionic parasympathetic nerves innervating the urinary bladder and again acts at postjunctional P2X1 receptors, and possibly also a P2X1+4 heteromer, to elicit smooth muscle contraction. In both cases the neurotransmitter actions of ATP are terminated by dephosphorylation by extracellular, membrane-bound enzymes and soluble nucleotidases released from postganglionic nerves. There are indications of an increased contribution of ATP to control of blood pressure in hypertension, but further research is needed to clarify this possibility. More promising is the upregulation of P2X receptors in dysfunctional bladder, including interstitial cystitis, idiopathic detrusor instability and overactive bladder syndrome. Consequently, these roles of ATP are of great therapeutic interest and are increasingly being targeted by pharmaceutical companies.
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Affiliation(s)
- Charles Kennedy
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral Street, Glasgow G4 0RE, United Kingdom.
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Furness JB, Callaghan BP, Rivera LR, Cho HJ. The enteric nervous system and gastrointestinal innervation: integrated local and central control. Adv Exp Med Biol. 2014;817:39-71. [PMID: 24997029 DOI: 10.1007/978-1-4939-0897-4_3] [Citation(s) in RCA: 465] [Impact Index Per Article: 46.5] [Reference Citation Analysis] [What about the content of this article? (0)] [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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Abstract
The past half century has witnessed tremendous advances in our understanding of extracellular purinergic signaling pathways. Purinergic neurotransmission, in particular, has emerged as a key contributor in the efficient control mechanisms in the nervous system. The identity of the purine neurotransmitter, however, remains controversial. Identifying it is difficult because purines are present in all cell types, have a large variety of cell sources, and are released via numerous pathways. Moreover, studies on purinergic neurotransmission have relied heavily on indirect measurements of integrated postjunctional responses that do not provide direct information for neurotransmitter identity. This paper discusses experimental support for adenosine 5'-triphosphate (ATP) as a neurotransmitter and recent evidence for possible contribution of other purines, in addition to or instead of ATP, in chemical neurotransmission in the peripheral, enteric and central nervous systems. Sites of release and action of purines in model systems such as vas deferens, blood vessels, urinary bladder and chromaffin cells are discussed. This is preceded by a brief discussion of studies demonstrating storage of purines in synaptic vesicles. We examine recent evidence for cell type targets (e.g., smooth muscle cells, interstitial cells, neurons and glia) for purine neurotransmitters in different systems. This is followed by brief discussion of mechanisms of terminating the action of purine neurotransmitters, including extracellular nucleotide hydrolysis and possible salvage and reuptake in the cell. The significance of direct neurotransmitter release measurements is highlighted. Possibilities for involvement of multiple purines (e.g., ATP, ADP, NAD(+), ADP-ribose, adenosine, and diadenosine polyphosphates) in neurotransmission are considered throughout.
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Affiliation(s)
| | - Leonie Durnin
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, United States
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Durnin L, Hwang SJ, Kurahashi M, Drumm BT, Ward SM, Sasse KC, Sanders KM, Mutafova-Yambolieva VN. Uridine adenosine tetraphosphate is a novel neurogenic P2Y1 receptor activator in the gut. Proc Natl Acad Sci U S A 2014; 111:15821-6. [PMID: 25341729 DOI: 10.1073/pnas.1409078111] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Enteric purinergic motor neurotransmission, acting through P2Y1 receptors (P2Y1R), mediates inhibitory neural control of the intestines. Recent studies have shown that NAD(+) and ADP ribose better meet criteria for enteric inhibitory neurotransmitters in colon than ATP or ADP. Here we report that human and murine colon muscles also release uridine adenosine tetraphosphate (Up4A) spontaneously and upon stimulation of enteric neurons. Release of Up4A was reduced by tetrodotoxin, suggesting that at least a portion of Up4A is of neural origin. Up4A caused relaxation (human and murine colons) and hyperpolarization (murine colon) that was blocked by the P2Y1R antagonist, MRS 2500, and by apamin, an inhibitor of Ca(2+)-activated small-conductance K(+) (SK) channels. Up4A responses were greatly reduced or absent in colons of P2ry1(-/-) mice. Up4A induced P2Y1R-SK-channel-mediated hyperpolarization in isolated PDGFRα(+) cells, which are postjunctional targets for purinergic neurotransmission. Up4A caused MRS 2500-sensitive Ca(2+) transients in human 1321N1 astrocytoma cells expressing human P2Y1R. Up4A was more potent than ATP, ADP, NAD(+), or ADP ribose in colonic muscles. In murine distal colon Up4A elicited transient P2Y1R-mediated relaxation followed by a suramin-sensitive contraction. HPLC analysis of Up4A degradation suggests that exogenous Up4A first forms UMP and ATP in the human colon and UDP and ADP in the murine colon. Adenosine then is generated by extracellular catabolism of ATP and ADP. However, the relaxation and hyperpolarization responses to Up4A are not mediated by its metabolites. This study shows that Up4A is a potent native agonist for P2Y1R and SK-channel activation in human and mouse colon.
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Galione A. A primer of NAADP-mediated Ca(2+) signalling: From sea urchin eggs to mammalian cells. Cell Calcium 2014; 58:27-47. [PMID: 25449298 DOI: 10.1016/j.ceca.2014.09.010] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 09/28/2014] [Accepted: 09/29/2014] [Indexed: 02/04/2023]
Abstract
Since the discovery of the Ca(2+) mobilizing effects of the pyridine nucleotide metabolite, nicotinic acid adenine dinucleotide phosphate (NAADP), this molecule has been demonstrated to function as a Ca(2+) mobilizing intracellular messenger in a wide range of cell types. In this review, I will briefly summarize the distinct principles behind NAADP-mediated Ca(2+) signalling before going on to outline the role of this messenger in the physiology of specific cell types. Central to the discussion here is the finding that NAADP principally mobilizes Ca(2+) from acidic organelles such as lysosomes and it is this property that allows NAADP to play a unique role in intracellular Ca(2+) signalling. Lysosomes and related organelles are small Ca(2+) stores but importantly may also initiate a two-way dialogue with other Ca(2+) storage organelles to amplify Ca(2+) release, and may be strategically localized to influence localized Ca(2+) signalling microdomains. The study of NAADP signalling has created a new and fruitful focus on the lysosome and endolysosomal system as major players in calcium signalling and pathophysiology.
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Affiliation(s)
- Antony Galione
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
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Jiménez M, Clavé P, Accarino A, Gallego D. Purinergic neuromuscular transmission in the gastrointestinal tract; functional basis for future clinical and pharmacological studies. Br J Pharmacol 2014; 171:4360-75. [PMID: 24910216 DOI: 10.1111/bph.12802] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 05/14/2014] [Accepted: 05/24/2014] [Indexed: 12/13/2022] Open
Abstract
Nerve-mediated relaxation is necessary for the correct accomplishment of gastrointestinal (GI) motility. In the GI tract, NO and a purine are probably released by the same inhibitory motor neuron as inhibitory co-transmitters. The P2Y1 receptor has been recently identified as the receptor responsible for purinergic smooth muscle hyperpolarization and relaxation in the human gut. This finding has been confirmed in P2Y1 -deficient mice where purinergic neurotransmission is absent and transit time impaired. However, the mechanisms responsible for nerve-mediated relaxation, including the identification of the purinergic neurotransmitter(s) itself, are still debatable. Possibly different mechanisms of nerve-mediated relaxation are present in the GI tract. Functional demonstration of purinergic neuromuscular transmission has not been correlated with structural studies. Labelling of purinergic neurons is still experimental and is not performed in routine pathology studies from human samples, even when possible neuromuscular impairment is suspected. Accordingly, the contribution of purinergic neurotransmission in neuromuscular diseases affecting GI motility is not known. In this review, we have focused on the physiological mechanisms responsible for nerve-mediated purinergic relaxation providing the functional basis for possible future clinical and pharmacological studies on GI motility targeting purine receptors.
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Affiliation(s)
- Marcel Jiménez
- Department of Cell Biology, Physiology and Immunology, Neurosciences 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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Kurahashi M, Mutafova-Yambolieva V, Koh SD, Sanders KM. Platelet-derived growth factor receptor-α-positive cells and not smooth muscle cells mediate purinergic hyperpolarization in murine colonic muscles. Am J Physiol Cell Physiol 2014; 307:C561-70. [PMID: 25055825 DOI: 10.1152/ajpcell.00080.2014] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Enteric inhibitory neurotransmission is an important feature of the neural regulation of gastrointestinal motility. Purinergic neurotransmission, via P2Y1 receptors, mediates one phase of inhibitory neural control. For decades, ATP has been assumed to be the purinergic neurotransmitter and smooth muscle cells (SMCs) have been considered the primary targets for inhibitory neurotransmission. Recent experiments have cast doubt on both of these assumptions and suggested that another cell type, platelet-derived growth factor receptor-α-positive (PDGFRα(+)) cells, is the target for purinergic neurotransmission. We compared responses of PDGFRα(+) cells and SMCs to several purine compounds to determine if these cells responded in a manner consistent with enteric inhibitory neurotransmission. ATP hyperpolarized PDGFRα(+) cells but depolarized SMCs. Only part of the ATP response in PDGFRα(+) cells was blocked by MRS 2500, a P2Y1 antagonist. ADP, MRS 2365, β-NAD, and adenosine 5-diphosphate-ribose, P2Y1 agonists, hyperpolarized PDGFRα(+) cells, and these responses were blocked by MRS 2500. Adenosine 5-diphosphate-ribose was more potent in eliciting hyperpolarization responses than β-NAD. P2Y1 agonists failed to elicit responses in SMCs. Small hyperpolarization responses were elicited in SMCs by a small-conductance Ca(2+)-activated K(+) channel agonist, cyclohexyl-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine, consistent with the low expression and current density of small-conductance Ca(2+)-activated K(+) channels in these cells. Large-amplitude hyperpolarization responses, elicited in PDGFRα(+) cells, but not SMCs, by P2Y1 agonists are consistent with the generation of inhibitory junction potentials in intact muscles in response to purinergic neurotransmission. The responses of PDGFRα(+) cells and SMCs to purines suggest that SMCs are unlikely targets for purinergic neurotransmission in colonic muscles.
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Affiliation(s)
- Masaaki Kurahashi
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | | | - Sang Don Koh
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
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Burnstock G. Purinergic signalling in the gastrointestinal tract and related organs in health and disease. Purinergic Signal 2014; 10:3-50. [PMID: 24307520 PMCID: PMC3944042 DOI: 10.1007/s11302-013-9397-9] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 10/24/2013] [Indexed: 01/04/2023] Open
Abstract
Purinergic signalling plays major roles in the physiology and pathophysiology of digestive organs. Adenosine 5'-triphosphate (ATP), together with nitric oxide and vasoactive intestinal peptide, is a cotransmitter in non-adrenergic, non-cholinergic inhibitory neuromuscular transmission. P2X and P2Y receptors are widely expressed in myenteric and submucous enteric plexuses and participate in sympathetic transmission and neuromodulation involved in enteric reflex activities, as well as influencing gastric and intestinal epithelial secretion and vascular activities. Involvement of purinergic signalling has been identified in a variety of diseases, including inflammatory bowel disease, ischaemia, diabetes and cancer. Purinergic mechanosensory transduction forms the basis of enteric nociception, where ATP released from mucosal epithelial cells by distension activates nociceptive subepithelial primary afferent sensory fibres expressing P2X3 receptors to send messages to the pain centres in the central nervous system via interneurons in the spinal cord. Purinergic signalling is also involved in salivary gland and bile duct secretion.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London, NW3 2PF, UK,
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Liñán-Rico A, Wunderlich JE, Grants IS, Frankel WL, Xue J, Williams KC, Harzman AE, Enneking JT, Cooke HJ, Christofi FL. Purinergic autocrine regulation of mechanosensitivity and serotonin release in a human EC model: ATP-gated P2X3 channels in EC are downregulated in ulcerative colitis. Inflamm Bowel Dis 2013; 19:2366-79. [PMID: 23917247 DOI: 10.1097/MIB.0b013e31829ecf4d] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND Alterations in 5-hydroxytryptamine (HT) signaling in inflamed gut may contribute to pathogenesis of inflammatory bowel diseases. Adenosine 5'-triphosphate (ATP) regulates mucosal-mechanosensory reflexes and ATP receptors are sensitive to mucosal inflammation. Yet, it remains unknown whether ATP can modulate 5-HT signaling in enterochromaffin cells (EC). We tested the novel purinergic hypothesis that ATP is a critical autocrine regulator of EC mechanosensitivity and whether EC expression of ATP-gated P2X3-ion channels is altered in inflammatory bowel diseases. METHODS Laser confocal (fluo-4) Ca imaging was performed in 1947 BON cells. Chemical stimulation or mechanical stimulation (MS) was used to study 5-HT or ATP release in human BON or surgical mucosal specimens, and purine receptors by reverse transcription-polymerase chain reaction, Western Blot, or P2X3-immunoreactivity in BON or 5-HT human EC (hEC) in 11 control and 10 severely inflamed ulcerative colitis (UC) cases. RESULTS ATP or MS triggered Ca-transients or 5-HT release in BON. ATP or adenosine diphosphate increased 5-HT release 5-fold. MS caused ATP release, detected after 5'ecto-ATPase inhibition by ARL67156. ARL67156 augmented and apyrase blocked Ca/5-HT mechanosensitive responses. 2-Methyl-thio-adenosine diphosphate 5'-monophosphate-evoked (P2Y1,12) or mechanically-evoked responses were blocked or augmented by a P2Y1,12 antagonist, MRS2179, in different cells or inhibited by U73122. A P2Y12 antagonist, 2MeSAMP, augmented responses. A P2X1,3 agonist, α,β-MeATP, triggered Ca responses, whereas a P2X1,2/3,3 antagonist, 2',3'-O-(2,4,6-trinitrophenyl)-ATP, blocked mechanical responses or cell-surface 5'ATP- labeling. In hEC, α,β-MeATP stimulated 5-HT release. In UC, P2X3-immunoreactivity decreased from 15% to 0.2% of 5-HThECs. Human mucosa and BON expressed P2X1, P2X3, P2X4, P2X5, P2Y1, P2Y2, P2Y4, P2Y6, P2Y11, and P2Y12R-messenger RNA transcripts. CONCLUSIONS ATP is a critical determinant of mechanosensation and 5-HT release via autocrine activation of slow P2Y1-phospholipase C/inositol-1,4,5-triphosphate-Ca or inhibitory P2Y12-purinergic pathways, and fast ATP-gated P2X3-channels. UC downregulation of P2X3-channels (or A2B) is postulated to mediate abnormal 5-HT signaling.
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Peri LE, Sanders KM, Mutafova-Yambolieva VN. Differential expression of genes related to purinergic signaling in smooth muscle cells, PDGFRα-positive cells, and interstitial cells of Cajal in the murine colon. Neurogastroenterol Motil 2013; 25:e609-20. [PMID: 23809506 PMCID: PMC3735650 DOI: 10.1111/nmo.12174] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 05/26/2013] [Indexed: 12/19/2022]
Abstract
BACKGROUND Purinergic signaling provides regulation of colonic motility. Smooth muscle cells (SMC), interstitial cells of Cajal (ICC), and platelet-derived growth factor receptor α-positive (PDGFRα(+) ) cells are electrically coupled and form a functional (SIP) syncytium that constitutes the receptive field for motor neurotransmitters in the tunica muscularis. Each cell type in the SIP syncytium has specialized functions in mediating motor neurotransmission. We compared gene transcripts for purinergic receptors and membrane-bound enzymes for purine degradation expressed by each cell type of the SIP syncytium. METHODS Fluorescence-activated cell sorting (FACS) was used to purify SMC, ICC, and PDGFRα(+) cells from mixed cell populations of colonic muscles dispersed from reporter strains of mice with constitutive expression of green fluorescent proteins. Differential expression of functional groups of genes related to purinergic signaling was determined by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). KEY RESULTS We detected marked phenotypic differences among SMC, ICC, and PDGFRα(+) cells. Substantial numbers of genes of importance in purinergic neurotransmission were enriched in PDGFRα(+) cells in relation to SMC and ICC. Notably, genes related to mediating effects and extracellular biotransformation of enteric purinergic inhibitory neurotransmitters were strongly expressed by PDGFRα(+) cells. CONCLUSIONS & INFERENCES Our results demonstrate differential expression of genes for proteins involved in purinergic signaling in the SIP syncytium. These results may further clarify the specific functions of each cell type, identify novel biomarkers for postjunctional cells, and provide hypotheses for further studies to understand the physiological roles of cells of the SIP syncytium.
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Affiliation(s)
- L. E. Peri
- Department of Physiology and Cell Biology; University of Nevada School of Medicine; Reno; NV; USA
| | - K. M. Sanders
- Department of Physiology and Cell Biology; University of Nevada School of Medicine; Reno; NV; USA
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Roberts JA, Durnin L, Sharkey KA, Mutafova-Yambolieva VN, Mawe GM. Oxidative stress disrupts purinergic neuromuscular transmission in the inflamed colon. J Physiol 2013; 591:3725-37. [PMID: 23732648 DOI: 10.1113/jphysiol.2013.254136] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Colitis, induced by trinitrobenzene sulfonic acid (TNBS) in guinea pig, leads to decreased purinergic neuromuscular transmission resulting in a reduction in inhibitory junction potentials (IJPs) in colonic circular muscle. We explored possible mechanisms responsible for this inflammation-induced neurotransmitter plasticity. Previous studies have suggested that the deficit in inflamed tissue involves decreased ATP release. We therefore hypothesized that decreased purinergic transmission results from inflammation-induced free radical damage to mitochondria, leading to decreased purine synthesis and release. Stimulus-induced release of purines was measured using high-performance liquid chromatography, and quantities of all purines measured were significantly reduced in the inflamed colons as compared to controls. To test whether decreased mitochondrial function affects the IJP, colonic muscularis preparations were treated with the mitochondrial ATP synthase inhibitors oligomycin or dicyclohexylcarbodiimide, which resulted in a significant reduction of IJP amplitude. Induction of oxidative stress in vitro, by addition of H2O2 to the preparation, also significantly reduced IJP amplitude. Purinergic neuromuscular transmission was significantly restored in TNBS-inflamed guinea pigs, and in dextran sodium sulfate-inflamed mice, treated with a free radical scavenger. Furthermore, propulsive motility in the distal colons of guinea pigs with TNBS colitis was improved by in vivo treatment with the free radical scavenger. We conclude that oxidative stress contributes to the reduction in purinergic neuromuscular transmission measured in animal models of colitis, and that these changes can be prevented by treatment with a free radical scavenger, resulting in improved motility.
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Affiliation(s)
- Jane A Roberts
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA
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