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Averin AS, Konakov MV, Pimenov OY, Galimova MH, Berezhnov AV, Nenov MN, Dynnik VV. Regulation of Papillary Muscle Contractility by NAD and Ammonia Interplay: Contribution of Ion Channels and Exchangers. MEMBRANES 2022; 12:1239. [PMID: 36557146 PMCID: PMC9785361 DOI: 10.3390/membranes12121239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Revised: 12/04/2022] [Accepted: 12/04/2022] [Indexed: 06/17/2023]
Abstract
Various models, including stem cells derived and isolated cardiomyocytes with overexpressed channels, are utilized to analyze the functional interplay of diverse ion currents involved in cardiac automaticity and excitation-contraction coupling control. Here, we used β-NAD and ammonia, known hyperpolarizing and depolarizing agents, respectively, and applied inhibitory analysis to reveal the interplay of several ion channels implicated in rat papillary muscle contractility control. We demonstrated that: 4 mM β-NAD, having no strong impact on resting membrane potential (RMP) and action potential duration (APD90) of ventricular cardiomyocytes, evoked significant suppression of isometric force (F) of paced papillary muscle. Reactive blue 2 restored F to control values, suggesting the involvement of P2Y-receptor-dependent signaling in β-NAD effects. Meantime, 5 mM NH4Cl did not show any effect on F of papillary muscle but resulted in significant RMP depolarization, APD90 shortening, and a rightward shift of I-V relationship for total steady state currents in cardiomyocytes. Paradoxically, NH4Cl, being added after β-NAD and having no effect on RMP, APD, and I-V curve, recovered F to the control values, indicating β-NAD/ammonia antagonism. Blocking of HCN, Kir2.x, and L-type calcium channels, Ca2+-activated K+ channels (SK, IK, and BK), or NCX exchanger reverse mode prevented this effect, indicating consistent cooperation of all currents mediated by these channels and NCX. We suggest that the activation of Kir2.x and HCN channels by extracellular K+, that creates positive and negative feedback, and known ammonia and K+ resemblance, may provide conditions required for the activation of all the chain of channels involved in the interplay. Here, we present a mechanistic model describing an interplay of channels and second messengers, which may explain discovered antagonism of β-NAD and ammonia on rat papillary muscle contractile activity.
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Affiliation(s)
- Alexey S. Averin
- Institute of Theoretical and Experimental Biophysics, the Russian Academy of Sciences, Pushchino 142290, Russia
| | - Maxim V. Konakov
- Institute of Theoretical and Experimental Biophysics, the Russian Academy of Sciences, Pushchino 142290, Russia
| | - Oleg Y. Pimenov
- Institute of Theoretical and Experimental Biophysics, the Russian Academy of Sciences, Pushchino 142290, Russia
| | - Miliausha H. Galimova
- Institute of Theoretical and Experimental Biophysics, the Russian Academy of Sciences, Pushchino 142290, Russia
| | - Alexey V. Berezhnov
- Institute of Cell Biophysics, the Russian Academy of Sciences, Pushchino 142290, Russia
| | - Miroslav N. Nenov
- Institute of Theoretical and Experimental Biophysics, the Russian Academy of Sciences, Pushchino 142290, Russia
| | - Vladimir V. Dynnik
- Institute of Theoretical and Experimental Biophysics, the Russian Academy of Sciences, Pushchino 142290, Russia
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2
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Vascular Ca V1.2 channels in diabetes. CURRENT TOPICS IN MEMBRANES 2022; 90:65-93. [PMID: 36368875 DOI: 10.1016/bs.ctm.2022.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Diabetic vasculopathy is a significant cause of morbidity and mortality in the diabetic population. Hyperglycemia, one of the central metabolic abnormalities in diabetes, has been associated with vascular dysfunction due to endothelial cell damage. However, studies also point toward vascular smooth muscle as a locus for hyperglycemia-induced vascular dysfunction. Emerging evidence implicates hyperglycemia-induced regulation of vascular L-type Ca2+ channels CaV1.2 as a potential mechanism for vascular dysfunction during diabetes. This chapter summarizes our current understanding of vascular CaV1.2 channels and their regulation during physiological and hyperglycemia/diabetes conditions. We will emphasize the role of CaV1.2 in vascular smooth muscle, the effects of elevated glucose on CaV1.2 function, and the mechanisms underlying its dysregulation in hyperglycemia and diabetes. We conclude by examining future directions and gaps in knowledge regarding CaV1.2 regulation in health and during diabetes.
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3
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Panther EJ, Dodd W, Clark A, Lucke-Wold B. Gastrointestinal Microbiome and Neurologic Injury. Biomedicines 2022; 10:biomedicines10020500. [PMID: 35203709 PMCID: PMC8962360 DOI: 10.3390/biomedicines10020500] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 02/16/2022] [Accepted: 02/18/2022] [Indexed: 02/05/2023] Open
Abstract
Communication between the enteric nervous system (ENS) of the gastrointestinal (GI) tract and the central nervous system (CNS) is vital for maintaining systemic homeostasis. Intrinsic and extrinsic neurological inputs of the gut regulate blood flow, peristalsis, hormone release, and immunological function. The health of the gut microbiome plays a vital role in regulating the overall function and well-being of the individual. Microbes release short-chain fatty acids (SCFAs) that regulate G-protein-coupled receptors to mediate hormone release, neurotransmitter release (i.e., serotonin, dopamine, noradrenaline, γ-aminobutyric acid (GABA), acetylcholine, and histamine), and regulate inflammation and mood. Further gaseous factors (i.e., nitric oxide) are important in regulating inflammation and have a response in injury. Neurologic injuries such as ischemic stroke, spinal cord injury, traumatic brain injury, and hemorrhagic cerebrovascular lesions can all lead to gut dysbiosis. Additionally, unfavorable alterations in the composition of the microbiota may be associated with increased risk for these neurologic injuries due to increased proinflammatory molecules and clotting factors. Interventions such as probiotics, fecal microbiota transplantation, and oral SCFAs have been shown to stabilize and improve the composition of the microbiome. However, the effect this has on neurologic injury prevention and recovery has not been studied extensively. The purpose of this review is to elaborate on the complex relationship between the nervous system and the microbiome and to report how neurologic injury modulates the status of the microbiome. Finally, we will propose various interventions that may be beneficial in the recovery from neurologic injury.
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Affiliation(s)
- Eric J. Panther
- Department of Neurosurgery, University of Florida, Gainesville, FL 32601, USA;
- Correspondence:
| | - William Dodd
- College of Medicine, University of Central Florida, Orlando, FL 32816, USA; (W.D.); (A.C.)
| | - Alec Clark
- College of Medicine, University of Central Florida, Orlando, FL 32816, USA; (W.D.); (A.C.)
| | - Brandon Lucke-Wold
- Department of Neurosurgery, University of Florida, Gainesville, FL 32601, USA;
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4
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King BF. P2X3 receptors participate in purinergic inhibition of gastrointestinal smooth muscle. Auton Neurosci 2021; 234:102830. [PMID: 34116466 DOI: 10.1016/j.autneu.2021.102830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 05/11/2021] [Accepted: 05/28/2021] [Indexed: 10/21/2022]
Abstract
The ATP analogue α,β-meATP is a potent relaxant of gastrointestinal smooth muscle, but its molecular target is uncertain inside the gut. α,β-meATP relaxed the carbachol-precontracted guinea-pig taenia coli in a concentration-dependent manner (EC50, 2.0 ± 0.1 μM). A luciferase-based assay confirmed that α,β-meATP solutions were minimally contaminated with ATP. α,β-meATP-evoked relaxations were inhibited by the competitive P2Y1 antagonist MRS2179 (pA2 = 5.36), but also by the competitive P2X3 antagonist, A-317491 (pA2 = 5.51). When MRS2179 and A-317491 were applied together, residual α,β-meATP responses converted from brief to prolonged relaxations. Sodium nitroprusside (a nitric oxide donor) also caused prolonged relaxations. Immunohistochemistry revealed that P2X3 receptors were present in myenteric ganglion cells and their varicose nerve terminals. The amplitude of α,β-meATP responses was not inhibited by TTX (NaV channel blocker) and ωCgTx (N-type CaV channel blocker). However, responses to α,β-meATP were inhibited by TEA (non-selective K+-channel blocker), indicating that relaxations involved opening K+-channels. The findings of this study are consistent with the conclusion that α,β-meATP stimulates Ca2+-permeable P2X3 receptors on varicose nerve terminals to release inhibitory nucleotides: 1) ATP and β-NAD release results in P2Y1-mediated brief relaxations; 2) another released transmitter (possibly NO) results in prolonged relaxations. Prejunctional P2X3 receptors represent a purinergic feed-forward mechanism to augment the action of inhibitory nerves on gut motility. This positive feed-forward mechanism may counter-balance the known negative feedback mechanism caused by adenosine and prejunctional A1 receptors on inhibitory motor nerves.
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Affiliation(s)
- Brian F King
- University College London (UCL), Research Department of Neuroscience, Pharmacology & Physiology (NPP), Gower Street, London WC1E 6BT, United Kingdom.
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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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6
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Nieves-Cintrón M, Flores-Tamez VA, Le T, Baudel MMA, Navedo MF. Cellular and molecular effects of hyperglycemia on ion channels in vascular smooth muscle. Cell Mol Life Sci 2021; 78:31-61. [PMID: 32594191 PMCID: PMC7765743 DOI: 10.1007/s00018-020-03582-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 06/10/2020] [Accepted: 06/22/2020] [Indexed: 12/13/2022]
Abstract
Diabetes affects millions of people worldwide. This devastating disease dramatically increases the risk of developing cardiovascular disorders. A hallmark metabolic abnormality in diabetes is hyperglycemia, which contributes to the pathogenesis of cardiovascular complications. These cardiovascular complications are, at least in part, related to hyperglycemia-induced molecular and cellular changes in the cells making up blood vessels. Whereas the mechanisms mediating endothelial dysfunction during hyperglycemia have been extensively examined, much less is known about how hyperglycemia impacts vascular smooth muscle function. Vascular smooth muscle function is exquisitely regulated by many ion channels, including several members of the potassium (K+) channel superfamily and voltage-gated L-type Ca2+ channels. Modulation of vascular smooth muscle ion channels function by hyperglycemia is emerging as a key contributor to vascular dysfunction in diabetes. In this review, we summarize the current understanding of how diabetic hyperglycemia modulates the activity of these ion channels in vascular smooth muscle. We examine underlying mechanisms, general properties, and physiological relevance in the context of myogenic tone and vascular reactivity.
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Affiliation(s)
- Madeline Nieves-Cintrón
- Department of Pharmacology, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Víctor A Flores-Tamez
- Department of Pharmacology, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Thanhmai Le
- Department of Pharmacology, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA
| | | | - Manuel F Navedo
- Department of Pharmacology, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA.
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7
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Dănilă MD, Piollet M, Aburel OM, Angoulvant D, Lefort C, Chadet S, Roger S, Muntean MD, Ivanes F. Modulation of P2Y11-related purinergic signaling in inflammation and cardio-metabolic diseases. Eur J Pharmacol 2020; 876:173060. [PMID: 32142768 DOI: 10.1016/j.ejphar.2020.173060] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 02/22/2020] [Accepted: 02/28/2020] [Indexed: 12/11/2022]
Abstract
Chronic inflammation is the hallmark of cardiovascular pathologies with a major role in both disease progression and occurrence of long-term complications. The massive release of ATP during the inflammatory process activates various purinergic receptors, including P2Y11. This receptor is less studied but ubiquitously expressed in all cells relevant for cardiovascular pathology: cardiomyocytes, fibroblasts, endothelial and immune cells. While several studies suggested a potential pro-inflammatory role for P2Y11 receptors, recent literature data are supportive of an anti-inflammatory profile characterized by the immunosuppression of dendritic cells, inhibition of fibroblast proliferation and of cytokines and ATP secretion. Moreover, modulation of its activity appears to mediate the positive inotropic effect of ATP and mitigate endothelial dysfunction, thus rendering this receptor a promising therapeutic target in the cardiovascular disease armamentarium. The aim of the present review is to summarize the current available knowledge on P2Y11-related purinergic signaling in the setting of inflammation and cardio-metabolic diseases.
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Affiliation(s)
- Maria-Daniela Dănilă
- Department of Functional Sciences - Pathophysiology, "Victor Babeș" University of Medicine and Pharmacy Timișoara, Romania
| | - Marie Piollet
- EA4245 Transplantation Immunity Inflammation, Faculty of Medicine - Tours University& Loire Valley Cardiovascular Collaboration, Tours, F37000, France
| | - Oana-Maria Aburel
- Department of Functional Sciences - Pathophysiology, "Victor Babeș" University of Medicine and Pharmacy Timișoara, Romania; Center for Translational Research and Systems Medicine, "Victor Babeș" University of Medicine and Pharmacy Timișoara, Romania
| | - Denis Angoulvant
- EA4245 Transplantation Immunity Inflammation, Faculty of Medicine - Tours University& Loire Valley Cardiovascular Collaboration, Tours, F37000, France; Cardiology Department, Trousseau Hospital, CHRU de Tours, F37000, Tours, France
| | - Claudie Lefort
- EA4245 Transplantation Immunity Inflammation, Faculty of Medicine - Tours University& Loire Valley Cardiovascular Collaboration, Tours, F37000, France
| | - Stéphanie Chadet
- EA4245 Transplantation Immunity Inflammation, Faculty of Medicine - Tours University& Loire Valley Cardiovascular Collaboration, Tours, F37000, France
| | - Sebastien Roger
- EA4245 Transplantation Immunity Inflammation, Faculty of Medicine - Tours University& Loire Valley Cardiovascular Collaboration, Tours, F37000, France
| | - Mirela-Danina Muntean
- Department of Functional Sciences - Pathophysiology, "Victor Babeș" University of Medicine and Pharmacy Timișoara, Romania; Center for Translational Research and Systems Medicine, "Victor Babeș" University of Medicine and Pharmacy Timișoara, Romania.
| | - Fabrice Ivanes
- EA4245 Transplantation Immunity Inflammation, Faculty of Medicine - Tours University& Loire Valley Cardiovascular Collaboration, Tours, F37000, France; Cardiology Department, Trousseau Hospital, CHRU de Tours, F37000, Tours, France
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8
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Martin-Aragon Baudel M, Espinosa-Tanguma R, Nieves-Cintron M, Navedo MF. Purinergic Signaling During Hyperglycemia in Vascular Smooth Muscle Cells. Front Endocrinol (Lausanne) 2020; 11:329. [PMID: 32528416 PMCID: PMC7256624 DOI: 10.3389/fendo.2020.00329] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 04/28/2020] [Indexed: 12/15/2022] Open
Abstract
The activation of purinergic receptors by nucleotides and/or nucleosides plays an important role in the control of vascular function, including modulation of vascular smooth muscle excitability, and vascular reactivity. Accordingly, purinergic receptor actions, acting as either ion channels (P2X) or G protein-coupled receptors (GCPRs) (P1, P2Y), target diverse downstream effectors, and substrates to regulate vascular smooth muscle function and vascular reactivity. Both vasorelaxant and vasoconstrictive effects have been shown to be mediated by different purinergic receptors in a vascular bed- and species-specific manner. Purinergic signaling has been shown to play a key role in altering vascular smooth muscle excitability and vascular reactivity following acute and short-term elevations in extracellular glucose (e.g., hyperglycemia). Moreover, there is evidence that vascular smooth muscle excitability and vascular reactivity is severely impaired during diabetes and that this is mediated, at least in part, by activation of purinergic receptors. Thus, purinergic receptors present themselves as important candidates mediating vascular reactivity in hyperglycemia, with potentially important clinical and therapeutic potential. In this review, we provide a narrative summarizing our current understanding of the expression, function, and signaling of purinergic receptors specifically in vascular smooth muscle cells and discuss their role in vascular complications following hyperglycemia and diabetes.
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Affiliation(s)
- Miguel Martin-Aragon Baudel
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
- *Correspondence: Miguel Martin-Aragon Baudel
| | - Ricardo Espinosa-Tanguma
- Departamento de Fisiologia y Biofisca, Universidad Autónoma San Luis Potosí, San Luis Potosí, Mexico
| | | | - Manuel F. Navedo
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
- Manuel F. Navedo
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9
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Prada MP, Syed AU, Buonarati OR, Reddy GR, Nystoriak MA, Ghosh D, Simó S, Sato D, Sasse KC, Ward SM, Santana LF, Xiang YK, Hell JW, Nieves-Cintrón M, Navedo MF. A G s-coupled purinergic receptor boosts Ca 2+ influx and vascular contractility during diabetic hyperglycemia. eLife 2019; 8:42214. [PMID: 30821687 PMCID: PMC6397001 DOI: 10.7554/elife.42214] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 02/16/2019] [Indexed: 12/21/2022] Open
Abstract
Elevated glucose increases vascular reactivity by promoting L-type CaV1.2 channel (LTCC) activity by protein kinase A (PKA). Yet, how glucose activates PKA is unknown. We hypothesized that a Gs-coupled P2Y receptor is an upstream activator of PKA mediating LTCC potentiation during diabetic hyperglycemia. Experiments in apyrase-treated cells suggested involvement of a P2Y receptor underlying the glucose effects on LTTCs. Using human tissue, expression for P2Y11, the only Gs-coupled P2Y receptor, was detected in nanometer proximity to CaV1.2 and PKA. FRET-based experiments revealed that the selective P2Y11 agonist NF546 and elevated glucose stimulate cAMP production resulting in enhanced PKA-dependent LTCC activity. These changes were blocked by the selective P2Y11 inhibitor NF340. Comparable results were observed in mouse tissue, suggesting that a P2Y11-like receptor is mediating the glucose response in these cells. These findings established a key role for P2Y11 in regulating PKA-dependent LTCC function and vascular reactivity during diabetic hyperglycemia.
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Affiliation(s)
- Maria Paz Prada
- Department of Pharmacology, University of California, Davis, Davis, United States
| | - Arsalan U Syed
- Department of Pharmacology, University of California, Davis, Davis, United States
| | - Olivia R Buonarati
- Department of Pharmacology, University of California, Davis, Davis, United States
| | - Gopireddy R Reddy
- Department of Pharmacology, University of California, Davis, Davis, United States
| | - Matthew A Nystoriak
- Diabetes & Obesity Center, Department of Medicine, University of Louisville, Kentucky, United States
| | - Debapriya Ghosh
- Department of Pharmacology, University of California, Davis, Davis, United States
| | - Sergi Simó
- Department of Cell Biology & Human Anatomy, University of California, Davis, Davis, United States
| | - Daisuke Sato
- Department of Pharmacology, University of California, Davis, Davis, United States
| | | | - Sean M Ward
- Department of Physiology & Cell Biology, University of Nevada, Reno, United States
| | - Luis F Santana
- Department of Physiology & Membrane Biology, University of California, Davis, Davis, United States
| | - Yang K Xiang
- Department of Pharmacology, University of California, Davis, Davis, United States.,VA Northern California Healthcare System, Mather, United States
| | - Johannes W Hell
- Department of Pharmacology, University of California, Davis, Davis, United States
| | | | - Manuel F Navedo
- Department of Pharmacology, University of California, Davis, Davis, United States
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10
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Purinergic Signalling in the Gut. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 891:91-112. [PMID: 27379638 DOI: 10.1007/978-3-319-27592-5_10] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The article will begin with the discovery of purinergic inhibitory neuromuscular transmission in the 1960s/1970s, the proposal for purinergic cotransmission in 1976 and the recognition that sympathetic nerves release adenosine 5'-triphosphate (ATP), noradrenaline and neuropeptide Y, while non-adrenergic, non-cholinergic inhibitory nerve cotransmitters are ATP, nitric oxide and vasoactive intestinal polypeptide in variable proportions in different regions of the gut. Later, purinergic synaptic transmission in the myenteric and submucosal plexuses was established and purinergic receptors expressed by both glial and interstitial cells. The focus will then be on purinergic mechanosensory transduction involving release of ATP from mucosal epithelial cells during distension to activate P2X3 receptors on submucosal sensory nerve endings. The responses of low threshold fibres mediate enteric reflex activity via intrinsic sensory nerves, while high threshold fibres initiate pain via extrinsic sensory nerves. Finally, the involvement of purinergic signalling in an animal model of colitis will be presented, showing that during distension there is increased ATP release, increased P2X3 receptor expression on calcitonin gene-related peptide-labelled sensory neurons and increased sensory nerve activity.
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11
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Altwaijry NA, Baron M, Wright DW, Coveney PV, Townsend-Nicholson A. An Ensemble-Based Protocol for the Computational Prediction of Helix-Helix Interactions in G Protein-Coupled Receptors using Coarse-Grained Molecular Dynamics. J Chem Theory Comput 2017; 13:2254-2270. [PMID: 28383913 PMCID: PMC5557214 DOI: 10.1021/acs.jctc.6b01246] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
![]()
The
accurate identification of the specific points of interaction
between G protein-coupled receptor (GPCR) oligomers is essential for
the design of receptor ligands targeting oligomeric receptor targets.
A coarse-grained molecular dynamics computer simulation approach would
provide a compelling means of identifying these specific protein–protein
interactions and could be applied both for known oligomers of interest
and as a high-throughput screen to identify novel oligomeric targets.
However, to be effective, this in silico modeling must provide accurate,
precise, and reproducible information. This has been achieved recently
in numerous biological systems using an ensemble-based all-atom molecular
dynamics approach. In this study, we describe an equivalent methodology
for ensemble-based coarse-grained simulations. We report the performance
of this method when applied to four different GPCRs known to oligomerize
using error analysis to determine the ensemble size and individual
replica simulation time required. Our measurements of distance between
residues shown to be involved in oligomerization of the fifth transmembrane
domain from the adenosine A2A receptor are in very good
agreement with the existing biophysical data and provide information
about the nature of the contact interface that cannot be determined
experimentally. Calculations of distance between rhodopsin, CXCR4,
and β1AR transmembrane domains reported to form contact
points in homodimers correlate well with the corresponding measurements
obtained from experimental structural data, providing an ability to predict
contact interfaces computationally. Interestingly, error analysis
enables identification of noninteracting regions. Our results confirm
that GPCR interactions can be reliably predicted using this novel
methodology.
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Affiliation(s)
- Nojood A Altwaijry
- Institute of Structural and Molecular Biology, Research Department of Structural and Molecular Biology, Division of Biosciences, University College London , London, WC1E 6BT, United Kingdom.,King Saud University , Riyadh, Kingdom of Saudi Arabia
| | - Michael Baron
- Institute of Structural and Molecular Biology, Research Department of Structural and Molecular Biology, Division of Biosciences, University College London , London, WC1E 6BT, United Kingdom
| | - David W Wright
- Centre for Computational Science, Department of Chemistry, University College London , London WC1H 0AJ, United Kingdom
| | - Peter V Coveney
- Centre for Computational Science, Department of Chemistry, University College London , London WC1H 0AJ, United Kingdom
| | - Andrea Townsend-Nicholson
- Institute of Structural and Molecular Biology, Research Department of Structural and Molecular Biology, Division of Biosciences, University College London , London, WC1E 6BT, United Kingdom
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Mañé N, Jiménez-Sábado V, Jiménez M. BPTU, an allosteric antagonist of P2Y1 receptor, blocks nerve mediated inhibitory neuromuscular responses in the gastrointestinal tract of rodents. Neuropharmacology 2016; 110:376-385. [PMID: 27496690 DOI: 10.1016/j.neuropharm.2016.07.033] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 06/28/2016] [Accepted: 07/26/2016] [Indexed: 12/28/2022]
Abstract
P2Y1 receptors mediate nerve mediated purinergic inhibitory junction potentials (IJP) and relaxations in the gastrointestinal (GI) tract in a wide range of species including rodents and humans. A new P2Y1 antagonist, with a non-nucleotide structure, BPTU, has recently been described using X-ray crystallography as the first allosteric G-protein-coupled receptor antagonist located entirely outside of the helical bundle. In this study, we tested its effect on purinergic responses in the gastrointestinal tract of rodents using electrophysiological and myographic techniques. BPTU concentration dependently inhibited purinergic inhibitory junction potentials and inhibition of spontaneous motility induced by electrical field stimulation in the colon of rats (EC50 = 0.3 μM) and mice (EC50 = 0.06 μM). Mechanical inhibitory responses were also concentration-dependently blocked in the stomach of both species. Compared to MRS2500, BPTU displays a lower potency. In the rat colon nicotine induced relaxation was also blocked by BPTU. BPTU also blocked the cessation of spontaneous contractility elicited by ADPβS and the P2Y1 agonist MRS2365. We conclude that BPTU is a novel antagonist with different structural and functional properties than nucleotidic antagonists that is able to block the P2Y1 receptor located at the neuromuscular junction of the GI tract.
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Affiliation(s)
- Noemí Mañé
- Department of Cell Biology, Physiology and Immunology and Neuroscience Institute, Universitat Autònoma de Barcelona, Barcelona, Spain.
| | - Verónica Jiménez-Sábado
- Department of Cell Biology, Physiology and Immunology and Neuroscience Institute, Universitat Autònoma de Barcelona, Barcelona, Spain.
| | - Marcel 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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13
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Dreisig K, Kornum BR. A critical look at the function of the P2Y11 receptor. Purinergic Signal 2016; 12:427-37. [PMID: 27246167 DOI: 10.1007/s11302-016-9514-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 04/17/2016] [Indexed: 11/30/2022] Open
Abstract
The P2Y11 receptor is a member of the purinergic receptor family. It has been overlooked, somewhat due to the lack of a P2ry11 gene orthologue in the murine genome, which prevents the generation of knockout mice, which have been so helpful for defining the roles of other P2Y receptors. Furthermore, some of the studies reported to date have methodological shortcomings, making it difficult to determine the function of P2Y11 with certainty. In this review, we discuss the lack of a murine "P2Y11-like receptor" and highlight the limitations of the currently available methods used to investigate the P2Y11 receptor. These methods include protein recognition with antibodies that show very little specificity, gene expression studies that completely overlook the existence of a fusion transcript between the adjacent PPAN gene and P2RY11, and agonists/antagonists reported to be specific for the P2Y11 receptor but which have not been tested for activity on numerous other adenosine 5'-triphosphate (ATP)-binding receptors. We suggest a set of criteria for evaluating whether a dataset describes effects mediated by the P2Y11 receptor. Following these criteria, we conclude that the current evidence suggests a role for P2Y11 in immune activation with cell type-specific effects.
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Affiliation(s)
- Karin Dreisig
- Molecular Sleep Laboratory, Department of Clinical Biochemistry, Rigshospitalet, Glostrup, Denmark
| | - Birgitte Rahbek Kornum
- Molecular Sleep Laboratory, Department of Clinical Biochemistry, Rigshospitalet, Glostrup, Denmark.
- Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Rigshospitalet, Glostrup, Denmark.
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14
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Mac Nair CE, Schlamp CL, Montgomery AD, Shestopalov VI, Nickells RW. Retinal glial responses to optic nerve crush are attenuated in Bax-deficient mice and modulated by purinergic signaling pathways. J Neuroinflammation 2016; 13:93. [PMID: 27126275 PMCID: PMC4850653 DOI: 10.1186/s12974-016-0558-y] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Accepted: 04/20/2016] [Indexed: 01/14/2023] Open
Abstract
Background Retinal ganglion cell (RGC) soma death is a consequence of optic nerve damage, including in optic neuropathies like glaucoma. The activation of the innate immune network in the retina after nerve damage has been linked to RGC pathology. Since the eye is immune privileged, innate immune functions are the responsibility of the glia, specifically the microglia, astrocytes, and Müller cells that populate the retina. Glial activation, leading to the production of inflammatory cytokines, is a hallmark feature of retinal injury resulting from optic nerve damage and purported to elicit secondary degeneration of RGC somas. Methods A mouse model of optic nerve crush (ONC) was used to study retinal glial activation responses. RGC apoptosis was blocked using Bax-deficient mice. Glial activation responses were monitored by quantitative PCR and immunofluorescent labeling in retinal sections of activation markers. ATP signaling pathways were interrogated using P2X receptor agonists and antagonists and Pannexin 1 (Panx1)-deficient mice with RGC-specific deletion. Results ONC induced activation of both macroglia and microglia in the retina, and both these responses were dramatically muted if RGC death was blocked by deletion of the Bax gene. Macroglial, but not microglial, activation was modulated by purinergic receptor activation. Release of ATP after optic nerve damage was not mediated by PANX1 channels in RGCs. Conclusions RGC death in response to ONC plays a principal stimulatory role in the retinal glial activation response. Electronic supplementary material The online version of this article (doi:10.1186/s12974-016-0558-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Caitlin E Mac Nair
- Department of Ophthalmology and Visual Sciences, University of Wisconsin, 571A Medical Sciences-1300 University Ave, Madison, WI, 53706, USA.,Cellular and Molecular Pathology Graduate Program, University of Wisconsin-Madison, 3170-10K/L MFCB, 1685 Highland Avenue, Madison, WI, 53705, USA
| | - Cassandra L Schlamp
- Department of Ophthalmology and Visual Sciences, University of Wisconsin, 571A Medical Sciences-1300 University Ave, Madison, WI, 53706, USA
| | - Angela D Montgomery
- Department of Ophthalmology and Visual Sciences, University of Wisconsin, 571A Medical Sciences-1300 University Ave, Madison, WI, 53706, USA
| | - Valery I Shestopalov
- Department of Ophthalmology, University of Miami Miller School of Medicine, 900 N.W. 17th Street, Miami, FL, 33136, USA.,Department of Cell Biology and Anatomy, University of Miami Miller School of Medicine, 900 N.W. 17th Street, Miami, FL, 33136, USA
| | - Robert W Nickells
- Department of Ophthalmology and Visual Sciences, University of Wisconsin, 571A Medical Sciences-1300 University Ave, Madison, WI, 53706, USA.
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15
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Browning KN, Travagli RA. Central nervous system control of gastrointestinal motility and secretion and modulation of gastrointestinal functions. Compr Physiol 2015; 4:1339-68. [PMID: 25428846 DOI: 10.1002/cphy.c130055] [Citation(s) in RCA: 316] [Impact Index Per Article: 35.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Although the gastrointestinal (GI) tract possesses intrinsic neural plexuses that allow a significant degree of autonomy over GI functions, the central nervous system (CNS) provides extrinsic neural inputs that regulate, modulate, and control these functions. While the intestines are capable of functioning in the absence of extrinsic inputs, the stomach and esophagus are much more dependent upon extrinsic neural inputs, particularly from parasympathetic and sympathetic pathways. The sympathetic nervous system exerts a predominantly inhibitory effect upon GI muscle and provides a tonic inhibitory influence over mucosal secretion while, at the same time, regulates GI blood flow via neurally mediated vasoconstriction. The parasympathetic nervous system, in contrast, exerts both excitatory and inhibitory control over gastric and intestinal tone and motility. Although GI functions are controlled by the autonomic nervous system and occur, by and large, independently of conscious perception, it is clear that the higher CNS centers influence homeostatic control as well as cognitive and behavioral functions. This review will describe the basic neural circuitry of extrinsic inputs to the GI tract as well as the major CNS nuclei that innervate and modulate the activity of these pathways. The role of CNS-centered reflexes in the regulation of GI functions will be discussed as will modulation of these reflexes under both physiological and pathophysiological conditions. Finally, future directions within the field will be discussed in terms of important questions that remain to be resolved and advances in technology that may help provide these answers.
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Affiliation(s)
- Kirsteen N Browning
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, Pennsylvania
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16
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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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17
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Mutafova-Yambolieva VN, Durnin L. The purinergic neurotransmitter revisited: a single substance or multiple players? Pharmacol Ther 2014; 144:162-91. [PMID: 24887688 PMCID: PMC4185222 DOI: 10.1016/j.pharmthera.2014.05.012] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 05/23/2014] [Indexed: 12/20/2022]
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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Martínez-Cutillas M, Gil V, Gallego D, Mañé N, Clavé P, Martín MT, Jiménez M. α,β-meATP mimics the effects of the purinergic neurotransmitter in the human and rat colon. Eur J Pharmacol 2014; 740:442-54. [PMID: 24998877 DOI: 10.1016/j.ejphar.2014.06.048] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 06/13/2014] [Accepted: 06/17/2014] [Indexed: 02/05/2023]
Abstract
The purine receptor involved in inhibitory responses in the gastrointestinal tract has been recently identified. P2Y1 receptor activation mediates the fast component of the inhibitory junction potential (IJPf) and the non-nitrergic relaxation. The aim of the present work has been to investigate which purinergic agonist better mimics endogenous responses. We used different agonist and antagonist of P2 receptors. Contractility and microelectrode experiments were used to compare the effects of exogenously added purines and electrical field stimulation (EFS)-induced nerve mediated effects in rat and human colonic strips. In rat colon, the IJPf and EFS-induced inhibition of contractions were concentration-dependently inhibited by the P2Y1 antagonist MRS2500 but not by iso-PPADS or NF023 (P2X antagonists) up to 1 μM. In samples from human colon, EFS-induced inhibition of contractions was inhibited by either MRS2500 or apamin (1 μM) but not by iso-PPADS. In both species, α,β-meATP, a stable analog of ATP, caused inhibition of spontaneous contractions. α,β-meATP effect was concentration-dependent (EC50: 2.7 μM rat, 4.4 μM human) and was antagonized by either MRS2500 or apamin but unaffected by P2X antagonists. ATP, ADP, β-NAD and ADP-ribose inhibited spontaneous contractions but did not show the same sensitivity profile to purine receptor antagonists as EFS-induced inhibition of contractions. The effect of α,β-meATP is due to P2Y1 receptor activation leading the opening of sKca channels. Accordingly, α,β-meATP mimics the endogenous purinergic mediator. In contrast, exogenously added putative neurotransmitters do not exactly mimic the endogenous mediator. Quick degradation by ecto-nuclease or different distribution of receptors (junctionally vs extrajunctionally) might explain these results.
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Affiliation(s)
- Míriam Martínez-Cutillas
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Víctor Gil
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Diana Gallego
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, (CIBERehd), Instituto de Salud Carlos III, Barcelona, Spain
| | - Noemí Mañé
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Pere Clavé
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, (CIBERehd), Instituto de Salud Carlos III, Barcelona, Spain; Fundació de Gastroenterologia Dr Vilardell and Department of Surgery, Hospital de Mataró, Mataró, Barcelona, Spain
| | - María Teresa Martín
- Department of Cell Biology, Physiology and Immunology, 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
| | - Marcel Jiménez
- Department of Cell Biology, Physiology and Immunology, 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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Belchamber K, Hall DA, Hourani SMO. Smoking enhances the proinflammatory effects of nucleotides on cytokine release from human lung. PLoS One 2014; 9:e99711. [PMID: 24978193 PMCID: PMC4076178 DOI: 10.1371/journal.pone.0099711] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 05/16/2014] [Indexed: 12/03/2022] Open
Abstract
Nucleotides have effects on immune cells which are complex but generally proinflammatory, and have been suggested to play a role in smoking-related lung diseases. However, there have been no studies directly measuring functional responses to nucleotides in human lungs taken from smokers. We used fragments of post mortem human lung from smokers and non-smokers, incubated them with a range of nucleotides (4–1000 µM) in the presence of lipopolysaccharide (LPS; 10 µg/ml) for 24 hours and measured cytokines (IL-1β, IFNγ, IL-17, TNFα, IL-6, IL-8, IL-2 and IL-10) in the supernatants using multiplex immunoassays. Although the basal cytokine levels in the smokers were generally higher in the smokers than the non-smokers, there were no significant differences in either the basal release or the LPS-stimulated release of any of the cytokines when lungs from smokers and non-smokers were compared. There were no significant effects of ATP, ADP, AMP, UTP, α,β-methylene-ATP, P1, P4-diATP, 2-methylthio-ATP or Bz-ATP on the release of cytokines from the lungs. However, the stable ATP analogue ATPγS increased the release of IL-1β and IFNγ, and the effect was greatly increased in lungs from smokers. In non-smokers but not in smokers ATPγS increased the release of IL-17. Overall these results clearly demonstrate for the first time that in normal human lung a stable ATP analogue can enhance LPS-induced pro-inflammatory cytokine release, and that these effects are greatly altered by a prior history of smoking. This provides strong support for the suggestion that nucleotides are involved in the pathogenesis of smoking-related diseases.
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Affiliation(s)
- Kylie Belchamber
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, United Kingdom
| | - David A. Hall
- Fibrosis Discovery Performance Unit, GlaxoSmithKline, Stevenage, Hertfordshire, United Kingdom
- * E-mail:
| | - Susanna M. O. Hourani
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, United Kingdom
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20
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Lu HL, Huang X, Wu YS, Zhang CM, Meng XM, Liu DH, Kim YC, Xu WX. Gastric nNOS reduction accompanied by natriuretic peptides signaling pathway upregulation in diabetic mice. World J Gastroenterol 2014; 20:4626-35. [PMID: 24782615 PMCID: PMC4000499 DOI: 10.3748/wjg.v20.i16.4626] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 10/14/2013] [Accepted: 11/02/2013] [Indexed: 02/06/2023] Open
Abstract
AIM To investigate the relationship between neuronal nitric oxide synthase (nNOS) expression and the natriuretic peptide signaling pathway in the gastric fundus of streptozotocin (STZ)-induced diabetic mice. METHODS Diabetic mice were induced by injection of STZ solution. Immunofluorescence labeling of HuC/D, nNOS and natriuretic peptide receptor-A, B, C (NPRs) in the gastric fundus (GF) was used to observe nNOS expression and whether NPRs exist on enteric neurons. The expression levels of nNOS and NPRs in the diabetic GF were examined by western blotting. An isometric force transducer recorded the electric field stimulation (EFS)-induced relaxation and contraction in the diabetic GF. An intracellular recording method assessed EFS-induced inhibitory junction potentials (IJP) on the GF. GF smooth muscles acquired from normal mice were incubated with different concentrations of the NPRs agonist C-type natriuretic peptide (CNP) for 24 h, after which their nNOS expressions were detected by western blotting. RESULTS Eight weeks after injection, 43 diabetic mice were obtained from mouse models injected with STZ. Immunofluorescence indicated that the number of NOS neurons was significantly decreased and that nNOS expression was significantly downregulated in the diabetic GF. The results of physiological and electrophysiological assays showed that the EFS-induced relaxation that mainly caused by NO was significantly reduced, while the contraction was enhanced in the diabetic GF. EFS-induced IJP showed that L-NAME sensitive IJP in the diabetic GF was significantly reduced compared with control mice. However, both NPR-A and NPR-B were detected on enteric neurons, and their expression levels were upregulated in the diabetic GF. The nNOS expression level was downregulated dose-dependently in GF smooth muscle tissues exposed to CNP. CONCLUSION These findings suggested that upregulation of the NPs signaling pathway may be involved in GF neuropathy caused by diabetes by decreasing nNOS expression.
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21
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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] [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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22
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Haas M, Ben-Moshe I, Fischer B, Reiser G. Sp-2-propylthio-ATP-α-B and Sp-2-propylthio-ATP-α-B,β-γ-dichloromethylene are novel potent and specific agonists of the human P2Y₁₁ receptor. Biochem Pharmacol 2013; 86:645-55. [PMID: 23810430 DOI: 10.1016/j.bcp.2013.06.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 06/13/2013] [Accepted: 06/14/2013] [Indexed: 11/28/2022]
Abstract
The human P2Y₁₁ nucleotide receptor mRNA was found in virtually all human tissues, and the receptor serves many physiological roles, such as immune response regulation. The Ala-87-Thr-P2Y₁₁ receptor single nucleotide polymorphism was linked to increased risk for acute myocardial infarction. To facilitate the development of new therapeutic applications involving cells expressing several P2 receptor subtypes, the availability of specific and potent agonists is mandatory. Here, we synthesized a series of novel adenine nucleotide derivatives, based upon the potent P2Y₁₁ receptor agonists AR-C67085. Features of the novel nucleotide derivatives are a propylthio substitution at C2-adenine and a Pα-borano or Pα-thio substitution of non-bridging oxygen atom. The latter substitutions introduce a chiral center at the α-phosphate. Sp-isomers of Pα-borano- and Rp-isomers of Pα-thio-substituted nucleotides are preferred by the P2Y₁₁ receptor. As recently reported by us, diastereoselectivity of the P2Y₁₁ receptor is opposite to that of the P2Y₁ receptor. Therefore, we exploit this characteristic to increase nucleotide selectivity. At the P2Y₁₁ receptor, the Sp-isomers of 2-propylthio-ATP-α-B (2B) and 2-propylthio-ATP-α-B,β-γ-dichloromethylene (4B) were the most potent of the novel nucleotide series, with EC₅₀ values of 0.03 μM for both, being ca. 80-fold more potent than 2-propylthio-ATP and ATP (EC₅₀ = 2.6 μM). We conclude that the borano-substitution at the α-phosphate of 2-propylthio-ATP enhances nucleotide potency at the P2Y₁₁ receptor. The combination with a Pβ-Pγ-dichloromethylene group in 4B results in a nucleotide, which shows higher selectivity for the P2Y₁₁ receptor over the P2Y₁₁ receptor than 2B making it the most promising of the novel P2Y₁₁ receptor agonists.
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Affiliation(s)
- Michael Haas
- Institute for Neurobiochemistry, Faculty of Medicine, Otto-von-Guericke University, Leipziger Str. 44, 39120 Magdeburg, Germany
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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] [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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Antonioli L, Colucci R, Pellegrini C, Giustarini G, Tuccori M, Blandizzi C, Fornai M. The role of purinergic pathways in the pathophysiology of gut diseases: pharmacological modulation and potential therapeutic applications. Pharmacol Ther 2013; 139:157-88. [PMID: 23588157 DOI: 10.1016/j.pharmthera.2013.04.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 03/15/2013] [Indexed: 02/08/2023]
Abstract
Gut homeostasis results from complex neuro-immune interactions aimed at triggering stereotypical and specific programs of coordinated mucosal secretion and powerful motor propulsion. A prominent role in the regulation of this highly integrated network, comprising a variety of immune/inflammatory cells and the enteric nervous system, is played by purinergic mediators. The cells of the digestive tract are literally plunged into a "biological sea" of functionally active nucleotides and nucleosides, which carry out the critical task of driving regulatory interventions on cellular functions through the activation of P1 and P2 receptors. Intensive research efforts are being made to achieve an integrated view of the purinergic system, since it is emerging that the various components of purinergic pathways (i.e., enzymes, transporters, mediators and receptors) are mutually linked entities, deputed to finely modulating the magnitude and the duration of purinergic signaling, and that alterations occurring in this balanced network could be intimately involved in the pathophysiology of several gut disorders. This review article intends to provide a critical appraisal of current knowledge on the purinergic system role in the regulation of gastrointestinal functions, considering these pathways as a whole integrated network, which is capable of finely controlling the levels of bioactive nucleotides and nucleosides in the biophase of their respective receptors. Special attention is paid to the mechanisms through which alterations in the various compartments of the purinergic system could contribute to the pathophysiology of gut disorders, and to the possibility of counteracting such dysfunctions by means of pharmacological interventions on purinergic molecular targets.
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Affiliation(s)
- Luca Antonioli
- Department of Clinical and Experimental Medicine, University of Pisa, Italy.
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25
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Bennett MR. The discovery of a new class of synaptic transmitters in smooth muscle 50 years ago and amelioration of coronary artery thrombosis. Acta Physiol (Oxf) 2013; 207:236-43. [PMID: 23167304 DOI: 10.1111/apha.12039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 10/21/2012] [Accepted: 11/06/2012] [Indexed: 12/11/2022]
Abstract
Clopidogrel and ticagrelor, antagonists to P2Y(12) receptor molecules on platelet membranes, significantly ameliorate acute myocardial infarction due to coronary artery thrombosis, the most common cause of death in the developed world. A personal account is given here of the foundational research that lead to the identification of P2Y receptors, carried out 50 years ago in the Melbourne University Zoology Department headed by Geoffrey Burnstock. In Christmas 1962, I made the serendipitous observation of large hyperpolarizing changes across the membranes of smooth muscle cells in the taenia coli of the intestine on stimulating its nerve supply. I then showed that these potentials relaxed the muscle and were not due to noradrenaline or acetylcholine, which were then the only substances known to be released from nerves. I called these non-adrenergic, non-cholinergic (NANC) terminals in the laboratory and showed that this NANC transmitter acted at receptor molecules on the muscle cells, promoting efflux of potassium ions, and so the observed potential changes. In 1968, Graeme Campbell showed that ATP relaxed the taenia coli muscle, and in 1969, David Satchell, using purine chromatography, showed that ATP was likely to be released from NANC terminals. The receptor molecules involved were shown to be exceptionally sensitive to 2-methylthio-ATP (Satchell and Macguire, 1975, J Pharmacol Exp Ther, 195, 540), and so belonged to the class P2Y receptors as designated by Abbracchio and Burnstock, with subclasses P2Y(1)-P2Y(12). The discovery of the role of P2Y(12) receptors in increasing thrombosis lead to the focused research that resulted in clopidogrel and ticagrelor.
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Affiliation(s)
- M. R. Bennett
- Brain and Mind Research Institute; University of Sydney; Camperdown; NSW; Australia
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King BF. Resolution and concordance in dissecting the compound inhibitory junction potential. J Physiol 2012; 590:1777-8. [PMID: 22532644 DOI: 10.1113/jphysiol.2012.230110] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Baqi Y, Müller CE. Convergent synthesis of the potent P2Y receptor antagonist MG 50-3-1 based on a regioselective Ullmann coupling reaction. Molecules 2012; 17:2599-615. [PMID: 22391596 PMCID: PMC6268193 DOI: 10.3390/molecules17032599] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 02/25/2012] [Accepted: 02/27/2012] [Indexed: 12/22/2022] Open
Abstract
MG 50-3-1 (3, trisodium 1-amino-4-{4-[4-chloro-6-(2-sulfophenylamino)-1,3,5-triazin-2-ylamino]-2-sulfophenylamino}-9,10-dioxo-9,10-dihydroanthracene 2-sulfonate) is the most potent and selective antagonist (IC₅₀ 4.6 nM) for "P2Y₁-like" nucleotide-activated membrane receptors in guinea-pig taenia coli responsible for smooth muscle relaxation. Full characterization of the compound, however, e.g., at the human P2Y₁ receptor, which is a novel potential target for antithrombotic drugs, as well as other P2 receptor subtypes, has been hampered due to difficulties in synthesizing the compound in sufficient quantity. MG 50-3-1 would be highly useful as a biological tool for detailed investigation of signal transduction in the gut. We have now developed a convenient, fast, mild, and efficient convergent synthesis of 3 based on retrosynthetic analysis. A new, regioselective Ullmann coupling reaction under microwave irradiation was successfully developed to obtain 1-amino-4-(4-amino-2-sulfophenylamino)-9,10-dioxo-9,10-dihydro-anthracene 2-sulfonate (8). Four different copper catalysts (Cu, CuCl, CuCl₂, and CuSO₄) were investigated at different pH values of sodium phosphate buffer, and in water in the absence or presence of base. Results showed that CuSO₄ in water in the presence of triethylamine provided the best conditions for the regioselective Ullmann coupling reaction yielding the key intermediate compound 8. A new synthon (sodium 2-(4,6-dichloro-1,3,5-triazin-2-ylamino)benzenesulfonate, 13) which can easily be obtained on a gram scale was prepared, and 13 was successfully coupled with 8 yielding the target compound 3.
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Affiliation(s)
| | - Christa E. Müller
- Author to whom correspondence should be addressed; ; Tel.: +49-228-73-2301; Fax: +49-228-73-2567
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Hwang SJ, Blair PJ, Durnin L, Mutafova-Yambolieva V, Sanders KM, Ward SM. P2Y1 purinoreceptors are fundamental to inhibitory motor control of murine colonic excitability and transit. J Physiol 2012; 590:1957-72. [PMID: 22371476 DOI: 10.1113/jphysiol.2011.224634] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Activation of enteric inhibitory motor neurons causes inhibitory junctional potentials (IJPs) and muscle relaxation in mammalian gastrointestinal (GI) muscles, including humans. IJPs in many GI muscles are bi-phasic with a fast initial hyperpolarization (fIJP) due to release of a purine neurotransmitter and a slower hyperpolarization component (sIJP) due to release of nitric oxide. We sought to characterize the nature of the post-junctional receptor(s) involved in transducing purinergic neural inputs in the murine colon using mice with genetically deactivated P2ry1. Wild-type mice had characteristic biphasic IJPs and pharmacological dissection confirmed that the fIJP was purinergic and the sIJP was nitrergic. The fIJP was completely absent in P2ry1(−/−) mice and the P2Y1 receptor antagonist MRS2500 had no effect on electrical activity or responses to electrical field stimulation of intrinsic nerves in these mice. Contractile experiments confirmed that purinergic responses were abolished in P2ry1(−/−) mice. Picospritzing of neurotransmitter candidates (ATP and its primary metabolite, ADP) and β-NAD (and its primary metabolite, ADP-ribose, ADPR) caused transient hyperpolarization responses in wild-type colons, but responses to β-NAD and ADPR were completely abolished in P2ry1(−/−) mice. Hyperpolarization and relaxation responses to ATP and ADP were retained in colons of P2ry1(−/−) mice. Video imaging revealed that transit of fecal pellets was significantly delayed in colons from P2ry1(−/−) mice. These data demonstrate the importance of purinergic neurotransmission in regulating colonic motility and confirm pharmacological experiments suggesting that purinergic neurotransmission is mediated via P2Y1 receptors.
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Affiliation(s)
- Sung Jin Hwang
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
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Gallego D, Gil V, Martínez-Cutillas M, Mañé N, Martín MT, Jiménez M. Purinergic neuromuscular transmission is absent in the colon of P2Y(1) knocked out mice. J Physiol 2012; 590:1943-56. [PMID: 22371472 DOI: 10.1113/jphysiol.2011.224345] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Purinergic and nitrergic co-transmission is the dominant mechanism responsible for neural-mediated smooth muscle relaxation in the gastrointestinal tract. The aim of the present paper was to test whether or not P2Y(1) receptors are involved in purinergic neurotransmission using P2Y(1)(−/−) knock-out mice. Tension and microelectrode recordings were performed on colonic strips. In wild type (WT) animals, electrical field stimulation (EFS) caused an inhibitory junction potential (IJP) that consisted of a fast IJP (MRS2500 sensitive, 1 μm) followed by a sustained IJP (N(ω)-nitro-L-arginine (L-NNA) sensitive, 1 mm). The fast component of the IJP was absent in P2Y(1)(−/−) mice whereas the sustained IJP (L-NNA sensitive) was recorded. In WT animals, EFS-induced inhibition of spontaneous motility was blocked by the consecutive addition of L-NNA and MRS2500. In P2Y(1)(−/−) mice, EFS responses were completely blocked by L-NNA. In WT and P2Y(1)(−/−) animals, L-NNA induced a smooth muscle depolarization but ‘spontaneous' IJP (MRS2500 sensitive) could be recorded in WT but not in P2Y(1)(−/−) animals. Finally, in WT animals, 1 μm MRS2365 caused a smooth muscle hyperpolarization that was blocked by 1 μm MRS2500. In contrast, 1 μm MRS2365 did not modify smooth muscle resting membrane potential in P2Y(1)(−/−) mice. β-Nicotinamide adenine dinucleotide (β-NAD, 1 mm) partially mimicked the effect of MRS2365. We conclude that P2Y(1) receptors mediate purinergic neurotransmission in the gastrointestinal tract and β-NAD partially fulfils the criteria to participate in rodent purinergic neurotransmission. The P2Y(1)(−/−) mouse is a useful animal model to study the selective loss of purinergic neurotransmission.
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Affiliation(s)
- Diana Gallego
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd) Instituto de Salud Carlos III, Barcelona, Spain
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Ohtomo K, Shatos MA, Vrouvlianis J, Li D, Hodges RR, Dartt DA. Increase of intracellular Ca2+ by purinergic receptors in cultured rat lacrimal gland myoepithelial cells. Invest Ophthalmol Vis Sci 2011; 52:9503-15. [PMID: 22039237 DOI: 10.1167/iovs.11-7809] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
PURPOSE To isolate and characterize cultured myoepithelial cells (MECs) from rat lacrimal gland and determine which purinergic receptor subtypes are present and functional in MECs. METHODS Rat lacrimal glands were subjected to collagenase digestion, and MECs were grown. RT-PCR was performed for the purinergic receptors P2X(7), P2Y(1), P2Y(11), and P2Y(13) on RNA isolated from the MECs. Immunofluorescence experiments were performed with antibodies against MEC markers and P2X(7), P2Y(1), P2Y(11), and P2Y(13) purinergic receptors. Proteins from MECs were separated using Western blot analysis techniques. In addition, cells were incubated with Fura 2 tetra acetoxymethyl ester, and intracellular [Ca(2+)] ([Ca(2+)](i)) was determined in response to P2 purinergic agonists. RESULTS MECs expressed the MEC proteins α-smooth muscle actin, vimentin, α-actinin, and adenylyl cyclase II. RT-PCR, Western blot, and immunofluorescence techniques demonstrated the presence of the purinergic receptors P2X(7), P2Y(1), P2Y(11), and P2Y(13). The purinergic agonists ATP, benzoylbenzoyl ATP (BzATP), α,β methylene ATP, UTP, 2-methylthioATP (MeSATP), and ATPγS increased [Ca(2+)](i). As BzATP binds to the P2X(7) receptor, specific characteristics of this receptor were investigated. Neither inhibitors of P2X(7) receptors nor removal of extracellular Mg(2+) or Ca(2+) had an effect on the BzATP-stimulated increase in [Ca(2+)](i). Repeated applications of BzATP desensitized this response. Inhibitors for P2Y(1), P2Y(11), and P2Y(13) each decreased the BzATP-stimulated increase in [Ca(2+)](i) with the P2Y(1) inhibitor most effective. CONCLUSIONS MECs can be isolated from rat lacrimal glands, and they express P2X(7), P2Y(1), P2Y(11), and P2Y(13) purinergic receptors. Surprisingly, BzATP binds the P2Y(1) receptor, which is primarily responsible for the BzATP-stimulated increase in [Ca(2+)](i).
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Affiliation(s)
- Kaori Ohtomo
- Schepens Eye Research Institute, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA
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Hoyle CH. Evolution of neuronal signalling: Transmitters and receptors. Auton Neurosci 2011; 165:28-53. [DOI: 10.1016/j.autneu.2010.05.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Revised: 05/09/2010] [Accepted: 05/18/2010] [Indexed: 11/16/2022]
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Gallego D, Gil V, Aleu J, Martinez-Cutillas M, Clavé P, Jimenez M. Pharmacological characterization of purinergic inhibitory neuromuscular transmission in the human colon. Neurogastroenterol Motil 2011; 23:792-e338. [PMID: 21585621 DOI: 10.1111/j.1365-2982.2011.01725.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
BACKGROUND In the present study, we further characterize the purinergic receptors mediating the inhibitory junction potential (IJP) and smooth muscle relaxation in the human colon using a new, potent and selective agonist (MRS2365), and antagonists (MR2279 and MRS2500) of the P2Y(1) receptor. The P2Y(12) antagonist AR-C66096 was tested as well. Using this pharmacological approach, we tested whether β-nicotinamide adenine dinucleotide (β-NAD) fulfilled the criteria to be considered an inhibitory neurotransmitter in the human colon. METHODS We carried out muscle bath and microelectrode experiments on circular strips from the human colon and calcium imaging recordings on HEK293 cells, which constitutively express the human P2Y(1) receptor. KEY RESULTS Both the fast component of IJP and non-nitrergic relaxation was concentration-dependently inhibited by MRS2279 and MRS2500. This antagonism was confirmed in HEK293 cells. However, AR-C66096 did not modify either inhibitory response. Adenosine 5'-Ο-2-thiodiphosphate and MRS2365 caused a smooth muscle hyperpolarization and transient inhibition of spontaneous motility that was antagonized by MRS2279 and MRS2500. β-Nicotinamide adenine dinucleotide inhibited the spontaneous motility (IC(50) = 3.3 mmol L(-1) ). Nevertheless, this effect was not antagonized by high concentrations of P2Y(1) antagonists. CONCLUSIONS & INFERENCES Inhibitory purinergic neuromuscular transmission in the human colon was pharmacologically assessed by the use of new P2Y(1) receptor antagonists MRS2179, MRS2279, and MRS2500. The rank order of potency of the P2Y(1) antagonists is MRS2500 > MRS2279 > MRS2179. We found that β-NAD partially fulfills the criteria to be considered an inhibitory neurotransmitter in the human colon, but the relative contribution of each purine (ATP/ADP vsβ-NAD) requires further studies.
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Affiliation(s)
- D Gallego
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, (CIBERehd), Instituto de Salud Carlos III, Barcelona, Spain
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Characterization of P2Y receptors mediating ATP induced relaxation in guinea pig airway smooth muscle: involvement of prostaglandins and K+ channels. Pflugers Arch 2011; 462:573-85. [PMID: 21800025 DOI: 10.1007/s00424-011-0997-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Revised: 06/14/2011] [Accepted: 07/15/2011] [Indexed: 01/13/2023]
Abstract
In airway smooth muscle (ASM), adenosine 5'-triphosphate (ATP) induces a relaxation associated with prostaglandin production. We explored the role of K(+) currents (I (K)) in this relaxation. ATP relaxed the ASM, and this effect was abolished by indomethacin. Removal of airway epithelium slightly diminished the ATP-induced relaxation at lower concentration without modifying the responses to ATP at higher concentrations. ATPγS and UTP induced a concentration-dependent relaxation similar to ATP; α,β-methylene-ATP was inactive from 1 to 100 μM. Suramin or reactive blue 2 (RB2), P2Y receptor antagonists, did not modify the relaxation, but their combination significantly reduced this effect of ATP. The relaxation was also inhibited by N-ethylmaleimide (NEM; which uncouples G proteins). In myocytes, the ATP-induced I (K) increment was not modified by suramin or RB2 but the combination of both drugs abolished it. This increment in the I (K) was also completely nullified by NEM and SQ 22,536. 4-Amynopyridine or iberiotoxin diminished the ATP-induced I (K) increment, and the combination of both substances diminished ATP-induced relaxation. The presence of P2Y(2) and P2Y(4) receptors in smooth muscle was corroborated by Western blot and confocal images. In conclusion, ATP: (1) produces relaxation by inducing the production of bronchodilator prostaglandins in airway smooth muscle, most likely by acting on P2Y(4) and P2Y(2) receptors; (2) induces I (K) increment through activation of the delayed rectifier K(+) channels and the high-conductance Ca(2+)-dependent K(+) channels, therefore both channels are implicated in the ATP-induced relaxation; and (3) this I (K) increment is mediated by prostaglandin production which in turns increase cAMP signaling pathway.
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Grasa L, Gil V, Gallego D, Martín MT, Jiménez M. P2Y(1) receptors mediate inhibitory neuromuscular transmission in the rat colon. Br J Pharmacol 2010; 158:1641-52. [PMID: 19906120 DOI: 10.1111/j.1476-5381.2009.00454.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND AND PURPOSE Inhibitory junction potentials (IJP) are responsible for smooth muscle relaxation in the gastrointestinal tract. The aim of this study was to pharmacologically characterize the neurotransmitters [nitric oxide (NO) and adenosine triphosphate (ATP)] and receptors involved at the inhibitory neuromuscular junctions in the rat colon using newly available P2Y(1) antagonists. EXPERIMENTAL APPROACH Organ bath and microelectrode recordings were used to evaluate the effect of drugs on spontaneous mechanical activity and resting membrane potential. IJP and mechanical relaxation were studied using electrical field stimulation (EFS). KEY RESULTS N(omega)-nitro-L-arginine (L-NNA) inhibited the slow component of the IJP and partially inhibited the mechanical relaxation induced by EFS. MRS2179, MRS2500 and MRS2279, all selective P2Y(1) receptor antagonists, inhibited the fast component of the IJP without having a major effect on the relaxation induced by EFS. The combination of both L-NNA and P2Y(1) antagonists inhibited the fast and the slow components of the IJP and completely blocked the mechanical relaxation induced by EFS. Sodium nitroprusside caused smooth muscle hyperpolarization and cessation of spontaneous motility that was prevented by oxadiazolo[4,3-alpha]quinoxalin-1-one. Adenosine 5'-O-2-thiodiphosphate, a preferential P2Y agonist, hyperpolarized smooth muscle cells and decreased spontaneous motility. This effect was inhibited by P2Y(1) antagonists. CONCLUSIONS AND IMPLICATIONS The co-transmission process in the rat colon involves ATP and NO. P2Y(1) receptors mediate the fast IJP and NO the slow IJP. The rank order of potency of the P2Y(1) receptor antagonists is MRS2500 greater than MRS2279 greater than MRS2179. P2Y(1) receptors might be potential pharmacological targets for the regulation of gastrointestinal motility.
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Affiliation(s)
- Laura Grasa
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra, Spain
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Alvarenga EC, Rodrigues R, Caricati-Neto A, Silva-Filho FC, Paredes-Gamero EJ, Ferreira AT. Low-intensity pulsed ultrasound-dependent osteoblast proliferation occurs by via activation of the P2Y receptor: role of the P2Y1 receptor. Bone 2010; 46:355-62. [PMID: 19781676 DOI: 10.1016/j.bone.2009.09.017] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Revised: 09/10/2009] [Accepted: 09/17/2009] [Indexed: 12/13/2022]
Abstract
Low-intensity pulsed ultrasound (LIPUS) is commonly used in the treatment of fractures and nonunion-promoting acceleration of healing fractures. In this report, we investigated the implication of the P2 receptors in osteoblast proliferation induced with LIPUS treatment. We observed that ADP, ATP, UTP, and UDP promote osteoblast increase and an increase of intracellular Ca(2+), through activation of P2Y receptors. Osteoblasts' expression of the P2Y(1), P2Y(2), P2Y(4), P2Y(6), P2Y(11), P2Y(12), and P2Y(13) receptors was confirmed. In addition, the participation of the P2Y(1) receptor in osteoblast increase and the ADP-dependent increase of Ca(2+) concentration were shown. Furthermore, release of ATP/purines was induced by LIPUS treatment. Finally, LIPUS-dependent osteoblast increase was abolished in the presence of the Ca(2+) chelator (BAPTA), the inositol 1,4,5-trisphosphate receptor antagonist (2-APB), and the selective P2Y(1) receptor antagonist (MRS2179). In conclusion, LIPUS treatment induces osteoblastogenesis via the release of purines, such as ATP, activating P2Y receptors, mainly the P2Y(1) receptor.
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Affiliation(s)
- Erika Costa Alvarenga
- Departamento de Biofísica, Universidade Federal de São Paulo, Rua Botucatu, São Paulo, SP, Brazil.
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Zhang Y, Lomax AE, Paterson WG. P2Y1 receptors mediate apamin-sensitive and -insensitive inhibitory junction potentials in murine colonic circular smooth muscle. J Pharmacol Exp Ther 2010; 333:602-11. [PMID: 20103587 DOI: 10.1124/jpet.109.160978] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Purinergic inhibitory neuromuscular transmission plays an important role in the control of intestinal motility. In most tissues this neurotransmission is apamin-sensitive, but recent studies in human colonic circular smooth muscle (CSM) suggest the presence of apamin-insensitive purinergic inhibitory junction potentials (IJPs). The current studies used conventional intracellular recordings on colonic CSM strips to characterize the purinergic IJPs in murine colonic CSM. P2Y1 receptor expression was examined by using reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry. The IJP induced by nerve stimulation (NS) of one and four pulses in neuronal nitric-oxide synthase knockout mice consists of an apamin-sensitive and a dominant apamin-resistant component. These are identical to the IJPs in wild-type and CD1 mice in the presence of N(omega)-nitro-l-arginine methyl ester (200 microM) and were significantly inhibited by alpha,beta-methylene ATP (50 microM), an analog of ATP. IJPs were not affected by the P2X receptor antagonist 2',3'-o-(2,4,6-trinitrophenyl)-ATP (10 microM). Furthermore, apamin-resistant IJPs induced by single-pulse NS were abolished by pyridoxal-phosphate-6-azophenyl-2',4'-disulfonate (100 microM), a P2 receptor antagonist; 2'-deoxy-N6-methyl adenosine 3,5-diphosphate (MRS-2179; 10 microM), a selective P2Y1 receptor antagonist; and tetrodotoxin (1 microM). Aboral NS induced apamin-sensitive purinergic IJPs, whereas oral and circumferential NS produced apamin-sensitive and -resistant IJPs, with the latter predominating. RT-PCR and immunohistochemistry confirmed the presence of P2Y1 receptors on smooth muscle and in the myenteric plexus. These data suggest that, depending on stimulus location, activation of P2Y1 receptors produces both apamin-sensitive and apamin-resistant IJPs in murine colonic CSM.
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Affiliation(s)
- Yong Zhang
- Gastrointestinal Diseases Research Unit, Queen's University, Kingston, Ontario, Canada
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Strong DS, Cornbrooks CF, Roberts JA, Hoffman JM, Sharkey KA, Mawe GM. Purinergic neuromuscular transmission is selectively attenuated in ulcerated regions of inflamed guinea pig distal colon. J Physiol 2010; 588:847-59. [PMID: 20064853 DOI: 10.1113/jphysiol.2009.185082] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
This study was undertaken to investigate neuromuscular transmission in regions of the inflamed colon in which motility is disrupted. Propulsive motility was evaluated in segments of control guinea pigs and those treated 6 days previously with trinitrobenzene sulfonic acid. Intracellular recordings were then obtained from circular muscle cells to examine excitatory and inhibitory junction potentials (EJPs and IJPs). In inflamed preparations, propulsion of fecal pellets was temporarily halted or obstructed at sites of mucosal damage, whereas the propulsive motility was linear in control colons. The amplitudes of evoked and spontaneous IJPs were significantly reduced in ulcerated regions of inflamed preparations, but EJPs were comparable to controls. Pharmacological dissection of the IJP revealed that the purinergic component was reduced, while the nitrergic IJP was slightly increased. Furthermore, the reduction in the purinergic IJP in inflamed preparations persisted in the presence of hexamethonium, suggesting that the deficit involved the inhibitory motor neuron and/or smooth muscle. Nerve fibre density was not altered in the circular muscle, and pre-contracted rings of inflamed colon relaxed normally to ATP, suggesting that the deficit involves altered ATP release and/or degradation. The P2Y(1) receptor antagonist MRS2179 slowed propulsive motility indicating that decreased purinergic neuromuscular transmission could contribute to the inflammation-induced motor deficit. We conclude that purinergic inhibitory neuronal input to the circular muscle is selectively reduced in regions of the colon in experimental colitis where the mucosa is damaged, and this is likely to contribute to altered motility in colitis by diminishing downstream relaxation during the peristaltic reflex.
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Affiliation(s)
- Derek S Strong
- D403A Given Building, Department of Anatomy and Neurobiology, University of Vermont, Burlington, VT 05405, USA
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Eddaoudi A, Townsend-Nicholson A, Timms JF, Schorge S, Jayasinghe SN. Molecular characterisation of post-bio-electrosprayed human brain astrocytoma cells. Analyst 2010; 135:2600-12. [DOI: 10.1039/c0an00213e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Lecea B, Martínez E, Aulí M, Opazo A, Clavé P. Selective stimulation of intrinsic excitatory and inhibitory motor pathways in porcine lower oesophageal sphincter. Neurogastroenterol Motil 2009; 21:1342-e130. [PMID: 19614864 DOI: 10.1111/j.1365-2982.2009.01357.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The mechanisms of stimulation of inhibitory and excitatory motor neurons (MNs) in the lower oesophageal sphincter (LOS) are not fully understood. The aim of this study was to assess the effect of selective stimulation of inhibitory and excitatory MNs in porcine LOS through nicotinic acetylcholine receptors (nAChRs), 5-HT(3) and P2X receptors. Circular LOS strips from adult pigs were studied in organ baths. We compared the effects of stimulation of MNs by electrical field stimulation (26 V, 0.3-20 Hz); nicotine (1-300 micromol L(-1)); 5-HT and 2-Me-5-HT (1 nmol(-1)-30 micromol L(-1)); and alpha,beta-methylene ATP (alpha,beta-meATP 1-100 micromol L(-1)); in standard Krebs solution; a non-adrenergic non-nitrergic non-purinergic (NANNNP) solution; and a non-adrenergic non-cholinergic (NANC) solution. Electrical stimulation of inhibitory MNs caused an intense LOS relaxation (-78.94 +/- 4.50% of LOS tone); and of excitatory MNs, a strong contraction (17.89 +/- 1.96 g). Nicotine 100 micromol L(-1) relaxed LOS (-84.67 +/- 3.98%) in standard Krebs solution, an effect reduced by Tetrodotoxin (TTX) 1 micromol L(-1). Nicotine induced a weak TTX-sensitive contraction (1.64 +/- 0.4 g) in NANNNP solution. 5-HT 10 micromol L(-1) and 2-Me-5-HT 30 micromol L(-1) contracted LOS in standard, NANC and NANNNP conditions, maximal responses (7.30 +/- 1.52 g, 3.50 +/- 0.18 g respectively) being reduced by TTX. alpha,beta-meATP 100 micromol L(-1) caused a LOS relaxation (-17.45 +/- 6.62%) unaffected by TTX in NANC solution, and a contraction (6.7 +/- 0.85 g) antagonized by TTX in NANNNP solution. Our results suggest selective mechanisms for stimulation of intrinsic excitatory and inhibitory motor pathways in porcine LOS. Inhibitory MNs are strongly stimulated by nAChRs and do not respond to stimulation of 5-HT(3) and P2X receptors. By contrast, excitatory MNs are stimulated through 5-HT(3) and P2X receptors, stimulation through nACRs being difficult and causing a weak response.
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Affiliation(s)
- B Lecea
- Department of Surgery, Hospital de Mataró, Universitat Autònoma de Barcelona, Spain
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Meis S, Hamacher A, Hongwiset D, Marzian C, Wiese M, Eckstein N, Royer HD, Communi D, Boeynaems JM, Hausmann R, Schmalzing G, Kassack MU. NF546 [4,4'-(carbonylbis(imino-3,1-phenylene-carbonylimino-3,1-(4-methyl-phenylene)-carbonylimino))-bis(1,3-xylene-alpha,alpha'-diphosphonic acid) tetrasodium salt] is a non-nucleotide P2Y11 agonist and stimulates release of interleukin-8 from human monocyte-derived dendritic cells. J Pharmacol Exp Ther 2009; 332:238-47. [PMID: 19815812 DOI: 10.1124/jpet.109.157750] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The G protein-coupled P2Y(11) receptor is involved in immune system modulation. In-depth physiological evaluation is hampered, however, by a lack of selective and potent ligands. By screening a library of sulfonic and phosphonic acid derivatives at P2Y(11) receptors recombinantly expressed in human 1321N1 astrocytoma cells (calcium and cAMP assays), the selective non-nucleotide P2Y(11) agonist NF546 [4,4'-(carbonylbis(imino-3,1-phenylene-carbonylimino-3,1-(4-methyl-phenylene)carbonylimino))-bis(1,3-xylene-alpha,alpha'-diphosphonic acid) tetrasodium salt] was identified. NF546 had a pEC(50) of 6.27 and is relatively selective for P2Y(11) over P2Y(1), P2Y(2), P2Y(4), P2Y(6), P2Y(12), P2X(1), P2X(2), and P2X(2)-X(3). Adenosine-5'-O-(3-thio)triphosphate (ATPgammaS), a nonhydrolyzable analog of the physiological P2Y(11) agonist ATP, and NF546 use a common binding site as suggested by molecular modeling studies and their competitive behavior toward the nanomolar potency antagonist NF340 [4,4'-(carbonylbis(imino-3,1-(4-methyl-phenylene)carbonylimino))bis(naphthalene-2,6-disulfonic acid) tetrasodium salt] in Schild analysis. The pA(2) of NF340 was 8.02 against ATPgammaS and 8.04 against NF546 (calcium assays). NF546 was further tested for P2Y(11)-mediated effects in monocyte-derived dendritic cells. Similarly to ATPgammaS, NF546 led to thrombospondin-1 secretion and inhibition of lipopolysaccharide-stimulated interleukin-12 release, whereas NF340 inhibited these effects. Further, for the first time, it was shown that ATPgammaS or NF546 stimulation promotes interleukin 8 (IL-8) release from dendritic cells, which could be inhibited by NF340. In conclusion, we have described the first selective, non-nucleotide agonist NF546 for P2Y(11) receptors in both recombinant and physiological expression systems and could show a P2Y(11)-stimulated IL-8 release, further supporting the immunomodulatory role of P2Y(11) receptors.
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Affiliation(s)
- Sabine Meis
- Institute of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Biochemistry, Heinrich-Heine-University of Duesseldorf, Duesseldorf, Germany
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Bintig W, Baumgart J, Walter WJ, Heisterkamp A, Lubatschowski H, Ngezahayo A. Purinergic signalling in rat GFSHR-17 granulosa cells: an in vitro model of granulosa cells in maturing follicles. J Bioenerg Biomembr 2009; 41:85-94. [PMID: 19191015 DOI: 10.1007/s10863-009-9199-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2008] [Accepted: 01/21/2009] [Indexed: 12/20/2022]
Abstract
Purinergic signalling in rat GFSHR-17 granulosa cells was characterised by Ca(2+)-imaging and perforated patch-clamp. We observed a resting intracellular Ca(2+)-concentration ([Ca(2+)](i)) of 100 nM and a membrane potential of -40 mV. This was consistent with high K(+)- and Cl(-) permeability and a high intracellular Cl(-) concentration of 40 mM. Application of ATP for 5-15 s every 3 min induced repeated [Ca(2+)](i) increases and a 30 mV hyperpolarization. The phospholipase C inhibitor U73122 or the IP(3)-receptor antagonist 2-aminoethoethyl diphenyl borate suppressed ATP responses. Further biochemical and pharmacological experiments revealed that ATP responses were related to stimulation of P2Y(2) and P2Y(4) receptors and that the [Ca(2+)](i) increase was a prerequisite for hyperpolarization. Inhibitors of Ca(2+)-activated channels or K(+) channels did not affect the ATP-evoked responses. Conversely, inhibitors of Cl(-) channels hyperpolarized cells to -70 mV and suppressed further ATP-evoked hyperpolarization. We propose that P2Y(2) and P2Y(4) receptors in granulosa cells modulate Cl(-) permeability by regulating Ca(2+)-release.
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Affiliation(s)
- Willem Bintig
- Institute of Biophysics, Leibniz University Hannover, Herrenhäuser-Str. 2, D-30419 Hannover, Germany
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Effects of excitatory and inhibitory neurotransmission on motor patterns of human sigmoid colon in vitro. Br J Pharmacol 2008; 155:1043-55. [PMID: 18846038 DOI: 10.1038/bjp.2008.332] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND AND PURPOSE To characterize the in vitro motor patterns and the neurotransmitters released by enteric motor neurons (EMNs) in the human sigmoid colon. EXPERIMENTAL APPROACH Sigmoid circular strips were studied in organ baths. EMNs were stimulated by electrical field stimulation (EFS) and through nicotinic ACh receptors. KEY RESULTS Strips developed weak spontaneous rhythmic contractions (3.67+/-0.49 g, 2.54+/-0.15 min) unaffected by the neurotoxin tetrodotoxin (TTX; 1 microM). EFS induced strong contractions during (on, 56%) or after electrical stimulus (off, 44%), both abolished by TTX. Nicotine (1-100 microM) inhibited spontaneous contractions. Latency of off-contractions and nicotine responses were reduced by N(G)-nitro-L-arginine (1 mM) and blocked after further addition of apamin (1 microM) or the P2Y(1) receptor antagonist MRS 2179 (10 microM) and were unaffected by the P2X antagonist NF279 (10 microM) or alpha-chymotrypsin (10 U mL(-1)). Amplitude of on- and off-contractions was reduced by atropine (1 microM) and the selective NK(2) receptor antagonist Bz-Ala-Ala-D-Trp-Phe-D-Pro-Pro-Nle-NH(2) (1 microM). MRS 2179 reduced the amplitude of EFS on- and off-contractions without altering direct muscular contractions induced by ACh (1 nM-1 mM) or substance P (1 nM-10 microM). CONCLUSIONS AND IMPLICATIONS Latency of EFS-induced off-contractions and inhibition of spontaneous motility by nicotine are caused by stimulation of inhibitory EMNs coreleasing NO and a purine acting at muscular P2Y(1) receptors through apamin-sensitive K(+) channels. EFS-induced on- and off-contractions are caused by stimulation of excitatory EMNs coreleasing ACh and tachykinins acting on muscular muscarinic and NK(2) receptors. Prejunctional P2Y(1) receptors might modulate the activity of excitatory EMNs. P2Y(1) and NK(2) receptors might be therapeutic targets for colonic motor disorders.
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