451
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Milano PM, Douillet CD, Riesenman PJ, Robinson WP, Beidler SK, Zarzaur BL, Rich PB. Intestinal ischemia-reperfusion injury alters purinergic receptor expression in clinically relevant extraintestinal organs. J Surg Res 2007; 145:272-8. [PMID: 17688885 PMCID: PMC2323452 DOI: 10.1016/j.jss.2007.03.028] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2007] [Revised: 03/01/2007] [Accepted: 03/13/2007] [Indexed: 01/21/2023]
Abstract
BACKGROUND Intestinal ischemia-reperfusion (IIR) injury is known to initiate the systemic inflammatory response syndrome, which often progresses to multiple organ failure. We investigated changes in purinoceptor expression in clinically relevant extra-intestinal organs following IIR injury. MATERIALS AND METHODS Anesthetized adult male BalbC mice were randomized to sham laparotomy (control, n = 5), or 15 min of superior mesenteric artery occlusion. Experimental ischemia was followed by a period of reperfusion [1 min (n = 6) or 1 h (n = 6)]. Mice were then sacrificed and lung, kidney, and intestinal tissues were harvested. Following RNA extraction, purinoceptor mRNA expression for P2Y2, A3, P2X7, A2b, P2Y4, and P2Y6 was analyzed using real-time RT-PCR. RESULTS Significant differences in purinoceptor expression were observed in the lungs and kidneys of mice exposed to IIR injury when compared to controls. Pulmonary P2Y2 receptor expression was increased in the 1 h IIR group when compared to control, while pulmonary A3 receptor expression was incrementally elevated following IIR injury. In the kidney, P2Y2 receptor expression was increased in the 1 h IIR group compared to both 1 min IIR and control, and A3 receptor expression was decreased in the 1 h IIR group compared to the 1 min IIR group. No significant changes were observed in the intestinal purinoceptor profiles. CONCLUSION Purinoceptor expression is altered in the murine lung and kidney, but not intestine following experimental IIR injury. These findings may implicate extracellular nucleotides and purinoceptors as possible mediators of the extra-intestinal organ dysfunction associated with IIR injury.
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Affiliation(s)
- Peter M. Milano
- Department of Surgery, Division of Trauma and Critical Care. The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Christelle D. Douillet
- Department of Surgery, Division of Trauma and Critical Care. The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Paul J. Riesenman
- Department of Surgery, Division of Trauma and Critical Care. The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - William P. Robinson
- Department of Surgery, Division of Trauma and Critical Care. The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Stephanie K. Beidler
- Department of Surgery, Division of Trauma and Critical Care. The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Ben L. Zarzaur
- Department of Surgery, Division of Trauma and Critical Care. The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Preston B. Rich
- Department of Surgery, Division of Trauma and Critical Care. The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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452
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Cheung KK, Coutinho-Silva R, Chan WY, Burnstock G. Early expression of adenosine 5'-triphosphate-gated P2X7 receptors in the developing rat pancreas. Pancreas 2007; 35:164-8. [PMID: 17632323 DOI: 10.1097/mpa.0b013e318053e00d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
OBJECTIVES Extracellular adenosine 5'-triphosphate modulates the functions of the adult pancreas via 2 nucleotide receptor families, the P2X and P2Y receptors. Expression of the P2X7 receptor has been demonstrated in islet cells of the pancreas, particularly the mature alpha cells that secrete glucagon. In the streptozotocin-induced diabetic model, a loss of insulin-secreting cells was accompanied by an increase in alpha cells that expressed the P2X7 receptor. METHODS In the present study, we have examined the expression of P2X7 receptors in the developing pancreas from embryonic days 10 (E10) to E18. RESULTS We detected P2X7 receptor-immunoreactive cells in pancreatic islet cells as early as E11' before glucagon expression. Subsequently, P2X7 receptors were expressed in glucagon-secreting cells at E12, and complete colocalization was observed at E14. Occasional colocalization of P2X7 receptors and insulin was observed in scattered cells at E12 and E14, but not at E18, when the glucagon- and insulin-secreting cells were almost completely segregated. CONCLUSIONS It was found that P2X7 receptors were expressed early in a subpopulation of glucagon- and insulin-immunopositive cells in developing islets and subsequently became restricted to glucagon-expressing cells as development proceeded. The possible functional significance of these changes is discussed.
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Affiliation(s)
- Kwok Kuen Cheung
- Autonomic Neuroscience Centre, Royal Free and University College Medical School, London, United Kingdom
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453
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Idzko M, Hammad H, van Nimwegen M, Kool M, Willart MAM, Muskens F, Hoogsteden HC, Luttmann W, Ferrari D, Di Virgilio F, Virchow JC, Lambrecht BN. Extracellular ATP triggers and maintains asthmatic airway inflammation by activating dendritic cells. Nat Med 2007; 13:913-9. [PMID: 17632526 DOI: 10.1038/nm1617] [Citation(s) in RCA: 487] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2006] [Accepted: 06/06/2007] [Indexed: 12/20/2022]
Abstract
Extracellular ATP serves as a danger signal to alert the immune system of tissue damage by acting on P2X or P2Y receptors. Here we show that allergen challenge causes acute accumulation of ATP in the airways of asthmatic subjects and mice with experimentally induced asthma. All the cardinal features of asthma, including eosinophilic airway inflammation, Th2 cytokine production and bronchial hyper-reactivity, were abrogated when lung ATP levels were locally neutralized using apyrase or when mice were treated with broad-spectrum P2-receptor antagonists. In addition to these effects of ATP in established inflammation, Th2 sensitization to inhaled antigen was enhanced by endogenous or exogenous ATP. The adjuvant effects of ATP were due to the recruitment and activation of lung myeloid dendritic cells that induced Th2 responses in the mediastinal nodes. Together these data show that purinergic signaling has a key role in allergen-driven lung inflammation that is likely to be amenable to therapeutic intervention.
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Affiliation(s)
- Marco Idzko
- Department of Pulmonary Medicine, Erasmus University Medical Center, Dr. Molewaterplein 50, P.O. Box 1738, 3000 DR Rotterdan, The Netherlands.
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454
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Abstract
The role of adenosine in exercise hyperaemia has been controversial. Accumulating evidence now demonstrates that adenosine is released into the venous efflux of exercising muscle and that adenosine is responsible for 20-40% of the maintained phase of the muscle vasodilatation that accompanies submaximal and maximal contractions. This adenosine is mainly generated from AMP that is released from the skeletal muscle fibres and dephosphorylated by ecto 5'nucleotidase bound to the sarcolemma. During exercise, the concentration of ecto 5'nucleotidase may be increased by translocation from the cytosol, while release of AMP and affinity of ecto 5'nucleotidase for AMP are increased by acidosis. The adenosine so formed, acts on extraluminal A(2A) receptors on the vascular smooth muscle. In addition, ATP is released from red blood cells into the plasma during exercise, in association with the unloading of O(2) from haemoglobin, while ATP and adenosine may be released from endothelium as a consequence of local hypoxia. It is unlikely that this intraluminal ATP, or adenosine, contributes significantly to exercise hyperaemia, for muscle vasodilatation induced by intraluminal ATP or adenosine is strongly nitric oxide dependent, while vasodilatation induced by adenosine in hypoxia is mediated by A(1) receptors. Neither is a recognized feature of exercise hyperaemia.
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Affiliation(s)
- Janice M Marshall
- Department of Physiology, The Medical School, Birmingham B15 2TT, UK.
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455
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P2Y1 receptor switches to neurons from glia in juvenile versus neonatal rat cerebellar cortex. BMC DEVELOPMENTAL BIOLOGY 2007; 7:77. [PMID: 17598884 PMCID: PMC1931589 DOI: 10.1186/1471-213x-7-77] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2007] [Accepted: 06/28/2007] [Indexed: 12/03/2022]
Abstract
Background In the CNS, several P2 receptors for extracellular nucleotides are identified on neurons and glial cells to participate to neuron-neuron, glia-glia and glia-neuron communication. Results In this work, we describe the cellular and subcellular presence of metabotropic P2Y1 receptor in rat cerebellum at two distinct developmental ages, by means of immunofluorescence-confocal and electron microscopy as well as western blotting and direct membrane separation techniques. At postnatal day 21, we find that P2Y1 receptor in addition to Purkinje neurons, is abundant on neuronal specializations identified as noradrenergic by anatomical, morphological and biochemical features. P2Y1 receptor immunoreactivity colocalizes with dopamine β-hydroxylase, tyrosine hydroxylase, neurofilament light chain, synaptophysin and flotillin, but not with glial fibrillary acidic protein for astrocytes. P2Y1 receptor is found enriched in membrane microdomains such as lipid rafts, in cerebellar synaptic vesicles, and is moreover visualized on synaptic varicosities by electron microscopy analysis. When examined at postnatal day 7, P2Y1 receptor immunoreactivity is instead predominantly expressed only on Bergmann and astroglial cells, as shown by colocalization with glial fibrillary acidic protein rather then neuronal markers. At this age, we moreover identify that P2Y1 receptor-positive Bergmann fibers wrap up doublecortin-positive granule cells stretching along them, while migrating through the cerebellar layers. Conclusion Membrane components including purinergic receptors are already known to mediate cellular contact and aggregation in platelets. Our results suggesting a potential role for P2Y1 protein in cell junction/communication and development, are totally innovative for the CNS.
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456
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Frizzo ME, Frizzo JK, Amadio S, Rodrigues JM, Perry ML, Bernardi G, Volonté C. Extracellular adenosine triphosphate induces glutamate transporter-1 expression in hippocampus. Hippocampus 2007; 17:305-15. [PMID: 17330863 DOI: 10.1002/hipo.20269] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
ATP can be significantly released following various brain insults and activates the extracellular signal-regulated protein kinase (ERK) pathway in astrocytes. Glutamate transporter-1 (GLT1) is the major forebrain astroglial glutamate transporter and its expression is stimulated also via ERK1/2 phosphorylation. We thus hypothesized that extracellular ATP could be a signal to GLT1 modulation in hippocampal slices obtained from rat. We indeed observed by western blot analysis that, after 1 mM ATP exposure, GLT1 expression, but not the glutamate-aspartate transporter, was enhanced. At the same time, high ATP induced significant rates of cell death in piramidal and granule cell layers, as shown by propidium iodide uptake, and increased glutamate uptake through GLT1 transporter. Also using confocal laser-scanning microscopy, we observed that ATP induced a vigorous and extensive GLT1-labeling on glial fibrillary acidic protein-positive cells. This stimulation was abolished by purine/pyrimidine nucleotide receptor antagonists and by MEK1/2 inhibitor. The present study demonstrates a novel mechanism of GLT1 regulation by extracellular ATP, reinforcing the evidence of cross talk between glutamatergic and purinergic systems.
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457
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Tsuda M. [A new mechanism of neuropathic pain through ATP receptors in spinal microglia]. Nihon Yakurigaku Zasshi 2007; 129:349-53. [PMID: 17507771 DOI: 10.1254/fpj.129.349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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458
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Abstract
This review is focused on purinergic neurotransmission, i.e., ATP released from nerves as a transmitter or cotransmitter to act as an extracellular signaling molecule on both pre- and postjunctional membranes at neuroeffector junctions and synapses, as well as acting as a trophic factor during development and regeneration. Emphasis is placed on the physiology and pathophysiology of ATP, but extracellular roles of its breakdown product, adenosine, are also considered because of their intimate interactions. The early history of the involvement of ATP in autonomic and skeletal neuromuscular transmission and in activities in the central nervous system and ganglia is reviewed. Brief background information is given about the identification of receptor subtypes for purines and pyrimidines and about ATP storage, release, and ectoenzymatic breakdown. Evidence that ATP is a cotransmitter in most, if not all, peripheral and central neurons is presented, as well as full accounts of neurotransmission and neuromodulation in autonomic and sensory ganglia and in the brain and spinal cord. There is coverage of neuron-glia interactions and of purinergic neuroeffector transmission to nonmuscular cells. To establish the primitive and widespread nature of purinergic neurotransmission, both the ontogeny and phylogeny of purinergic signaling are considered. Finally, the pathophysiology of purinergic neurotransmission in both peripheral and central nervous systems is reviewed, and speculations are made about future developments.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neurscience Centre, Royal Free and University College Medical School, London, UK.
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459
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Ojida A, Miyahara Y, Wongkongkatep J, Tamaru SI, Sada K, Hamachi I. Design of dual-emission chemosensors for ratiometric detection of ATP derivatives. Chem Asian J 2007; 1:555-63. [PMID: 17441093 DOI: 10.1002/asia.200600137] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Nucleoside pyrophosphate (nucleoside PP) derivatives are widespread in living cells and play pivotal roles in various biological events. We report novel fluorescence chemosensors for nucleoside PPs that make use of coordination chemistry. The chemosensors, which contain two Zn(II)-dipicolylamine units, bind strongly to nucleoside PPs (K(app)>10(6) M(-1)) in aqueous solution and sense them by a dual-emission change. Detailed fluorescence and UV/Vis spectral studies revealed that the emission changes of the chemosensors upon binding to nucleoside PPs can be ascribed to the loss of coordination between Zn(II) and the acridine fluorophore. This is a unique sensing system based on the anion-induced rearrangement of the coordination. Furthermore, we demonstrated the utility of these chemosensors in real-time monitoring of two important biological processes involving nucleoside PP conversion: the apyrase-catalyzed hydrolysis of nucleoside PPs and the glycosyl transfer catalyzed by beta-1,4-galactosyltransferase.
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Affiliation(s)
- Akio Ojida
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura Campus, Nishikyo-ku, Kyoto, 615-8510, Japan
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460
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Guzmán-Aránguez A, Irazu M, Yayon A, Pintor J. Effect of diadenosine polyphosphates in achondroplasic chondrocytes: inhibitory effect of Ap4A on FGF9 induced MAPK cascade. Biochem Pharmacol 2007; 74:448-56. [PMID: 17543287 DOI: 10.1016/j.bcp.2007.04.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2007] [Revised: 04/19/2007] [Accepted: 04/25/2007] [Indexed: 11/28/2022]
Abstract
Achondroplasia is characterised by a mutation in the gene that encodes for the FGF receptor type 3 (FGFR3), producing a hyperactivation of this receptor and a subsequent increase in MAPK activity. We have tested the ability of nucleotides to decrease the activation of MAPK in chondrocytes with achondroplasic FGFR3 receptor. Diadenosine tetraphosphate, Ap(4)A, reduced the phosphorylation of pERK1/2 triggered by FGF9 (38% reduction). Ap(4)A diminished the expression of achondroplasic FGFR3 receptor (65% reduction), stimulating FGFR3 receptor degradation. The action of Ap(4)A seems to be mediated by a dinucleotide receptor rather than by any other ATP receptor.
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Affiliation(s)
- Ana Guzmán-Aránguez
- Departamento de Bioquímica y Biología Molecular IV, E.U. Optica, Universidad Complutense de Madrid, c/Arcos de Jalón s/n, 28037 Madrid, Spain
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461
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Donnelly-Roberts DL, Jarvis MF. Discovery of P2X7 receptor-selective antagonists offers new insights into P2X7 receptor function and indicates a role in chronic pain states. Br J Pharmacol 2007; 151:571-9. [PMID: 17471177 PMCID: PMC2013998 DOI: 10.1038/sj.bjp.0707265] [Citation(s) in RCA: 221] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
ATP-sensitive P2X(7) receptors are localized on cells of immunological origin including peripheral macrophages and glial cells in the CNS. Activation of P2X(7) receptors leads to rapid changes in intracellular calcium concentrations, release of the proinflammatory cytokine interleukin-1beta and following prolonged agonist exposure, the formation of cytolytic pores in plasma membranes. Both the localization and functional consequences of P2X(7) receptor activation indicate a role in inflammatory processes. The phenotype of P2X(7) receptor gene-disrupted mice also indicates that P2X(7) receptor activation contributes to ongoing inflammation. More recently, P2X(7) receptor knockout data has also suggested a specific role in inflammatory and neuropathic pain states. The recent discovery of potent and highly selective antagonists for P2X(7) receptors has helped to further clarify P2X receptor pharmacology, expanded understanding of P2X(7) receptor signaling, and offers new evidence that P2X(7) receptors play a specific role in nociceptive signaling in chronic pain states. In this review, we incorporate the recent discoveries of novel P2X(7) receptor-selective antagonists with a brief update on P2X(7) receptor pharmacology and its therapeutic potential.
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Affiliation(s)
- D L Donnelly-Roberts
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories Abbott Park, IL, USA
| | - M F Jarvis
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories Abbott Park, IL, USA
- Author for correspondence:
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462
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Shao LJ, Liang SD, Li GL, Xu CS, Zhang CP. Exploration of P2X3 in the rat stellate ganglia after myocardial ischemia. Acta Histochem 2007; 109:330-7. [PMID: 17462717 DOI: 10.1016/j.acthis.2007.02.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2006] [Revised: 02/06/2007] [Accepted: 02/06/2007] [Indexed: 10/23/2022]
Abstract
ATP is implicated in peripheral pain signaling by actions on P2X receptors, especially P2X(3) receptor. Cardiac primary afferents running in the sympathetic nerves are considered to be essential pathways for transmission of cardiac nociception to the central nervous system. Because little is known about P2X(3) involvement in cardiac nociception, this study observed the difference in P2X(3) localization and expression in stellate ganglia (SG) from naive rats and in a pathological model of myocardial ischemic injury induced by repeated subcutaneous isoprenaline injections. Distribution of P2X(3) and morphometry of neurons in SG were investigated by immunohistochemistry, Western blotting, in situ hybridization (ISH) and by sterological study. Diffuse cytoplasmic P2X(3) immunolabelling was observed by light microsocopy. No nuclear labeling was detected. The intensity of P2X(3) labeling in the experimental myocardial ischemic injury group was increased in relation to that of the control group. Numerical densities of stellate ganglion neurons in the experimental group were higher than those of the control group. By Western blotting and ISH, the signals of P2X(3) protein and its mRNA in the myocardial ischemic group were higher than those of the control group. The P2X(3) labeling intensity and the numerical density in SG of the experimental myocardial ischemic injury group were enhanced, suggesting the involvement of P2X(3) receptor for the transmission of pain after myocardial ischemic injury.
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Affiliation(s)
- Li-Jian Shao
- Department of Anatomy, Medical College of Nanchang University, Nanchang, Jiangxi 330006, PR China
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463
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Burnstock G. Non-synaptic transmission at autonomic neuroeffector junctions. Neurochem Int 2007; 52:14-25. [PMID: 17493707 DOI: 10.1016/j.neuint.2007.03.007] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Accepted: 03/30/2007] [Indexed: 10/23/2022]
Abstract
Non-synaptic transmission is characteristic of autonomic neuroeffector junctions. The structure of the autonomic neuromuscular junction is described. The essential features are that: the terminal portions of autonomic nerve fibers are varicose and mobile, transmitters being released 'en passage' from varying distances from the effector cells; while there is no structural post-junctional specialization on effector cells, receptors for neurotransmitters accumulate on cell membranes at close junctions; muscle effectors are bundles rather than single smooth muscle cells, that are connected by gap junctions which allow electrotonic spread of activity between cells. A multiplicity of transmitters are utilized by autonomic nerves, and cotransmission occurs often involving synergistic actions of the cotransmitters, although pre- and post-junctional neuromodulation of neurotransmitter release also take place. It is suggested that autonomic neural control of immune, epithelial and endothelial cells also involves non-synaptic transmission.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, Royal Free and University College School of Medicine, Rowland Hill Street, London NW3 2PF, United Kingdom.
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464
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Comparative analysis of P2Y4 and P2Y6 receptor architecture in native and transfected neuronal systems. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:1592-9. [PMID: 17481575 DOI: 10.1016/j.bbamem.2007.03.020] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2006] [Revised: 02/28/2007] [Accepted: 03/21/2007] [Indexed: 10/23/2022]
Abstract
Although extensive studies provided molecular and pharmacological characterization of metabotropic P2Y receptors for extracellular nucleotides, little is still known about their quaternary structure. By the use of transfected cellular systems and SDS-PAGE, in our previous work we established the propensity of P2Y(4) receptor to form dimeric interactions. Here we focused on endogenously expressed P2Y(4) and P2Y(6) subtypes, comparing their oligomeric complexes under Blue Native (BN) gel electrophoresis. We provided evidence that P2Y(4) and P2Y(6) receptors form high order complexes in native neuronal phenotypes and that the oligomers can be disaggregated down to the dimeric P2Y(4) or to the dimeric and monomeric P2Y(6) receptor. Moreover, dimeric P2Y(4) and monomeric P2Y(6) proteins display selective microdomain partitioning in lipid rafts from specialized subcellular compartments such as synaptosomes. Ligand activation by UTP shifted the oligomerization of P2Y(6) but not of P2Y(4) receptor, as analysed by BN electrophoresis. Finally, whereas transfected P2Y(4) and P2Y(6) proteins homo-interact and posses the appropriate domains to associate with all P2Y(1,2,4,6,11) subtypes, in naive PC12 cells the endogenous P2Y(4) forms hetero-oligomers only with the P2Y(6) subunit. In conclusion, our results indicate that quaternary structure distinguishing P2Y(4) from P2Y(6) receptors might be crucial for specific ligand activation, membrane partitioning and consequent functional regulation.
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465
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Rieger A, Deitmer JW, Lohr C. Axon-glia communication evokes calcium signaling in olfactory ensheathing cells of the developing olfactory bulb. Glia 2007; 55:352-9. [PMID: 17136772 DOI: 10.1002/glia.20460] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Olfactory ensheathing cells (OECs) accompany receptor axons in the olfactory nerve and promote axonal growth into the central nervous system. The mechanisms underlying the communication between axons and OECs, however, have not been studied in detail yet. We investigated the effect of activity-dependent neuronal transmitter release on Ca(2+) signaling of OECs in acute mouse olfactory bulb slices using confocal Ca(2+) imaging. TTX-sensitive axonal activity upon electrical nerve stimulation triggers a rise in cytosolic Ca(2+) in OECs, which can be mimicked by application of DHPG, an agonist of metabotropic glutamate receptors (mGluRs). Both stimulation- and DHPG-induced Ca(2+) transients in OECs were abolished by depletion of intracellular Ca(2+) stores with cyclopiazonic acid (CPA). The mGluR(1)-specific antagonist CPCCOEt completely inhibited DHPG-evoked Ca(2+) transients, but reduced stimulation-induced Ca(2+) transients only partly, suggesting the involvement of another neurotransmitter. Application of ATP evoked CPA-sensitive Ca(2+) transients in OECs, which were inhibited by the P2Y(1)-specific antagonist MRS2179. Co-application of CPCCOEt and MRS2179 almost completely blocked the stimulation-induced Ca(2+) transients, indicating that they were mediated by mGluR(1) and P2Y(1) receptors. Our results show that OECs are able to respond to olfactory nerve activity with an increase in cytosolic Ca(2+) due to glutamate and ATP release.
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Affiliation(s)
- Anne Rieger
- Abteilung für Allgemeine Zoologie, Technische Universität Kaiserslautern, Postfach 3049, 67653 Kaiserslautern, Germany.
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466
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Baroni M, Pizzirani C, Pinotti M, Ferrari D, Adinolfi E, Calzavarini S, Caruso P, Bernardi F, Di Virgilio F. Stimulation of P2 (P2X7) receptors in human dendritic cells induces the release of tissue factor-bearing microparticles. FASEB J 2007; 21:1926-33. [PMID: 17314141 DOI: 10.1096/fj.06-7238com] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Receptors for extracellular nucleotides are the focus of increasing attention for their ability to cause release of plasma membrane vesicles (microparticles, MPs). Here, we show that monocyte-derived human dendritic cells (DCs) stimulated with a P2X7 receptor (P2X7R) agonist undergo a large release of MPs endowed with procoagulant activity. Functional and Western blot studies revealed that MPs contain the membrane-bound form of tissue factor (TF), a glycoprotein acting as essential cofactor of activated factor VII and triggering blood coagulation. Quiescent DCs express the membrane-bound (full length), as well as truncated alternatively spliced TF forms. DC reactivity to anti-TF Abs disappeared almost completely on stimulation with ATP or benzoyl ATP (BzATP), as shown by immunoblot and confocal microscopy analysis. Concurrently, TF reactivity and activity appeared in the vesicular fraction, indicating that MPs are important carriers for the dissemination of full-length TF form. Activity of MP-bound TF, comparable to that of relipidated recombinant TF, was dose dependently inhibited by the addition of a specific anti-human TF antibody. We infer that a large fraction of this protein, and its procoagulant potential, are "deliverable" after physiological or pathological stimuli. These findings might have implications for triggering and propagating coagulation in healthy and atherosclerotic vessels.
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Affiliation(s)
- Marcello Baroni
- Department of Biochemistry, University of Ferrara, Ferrara, Italy
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467
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Yamamoto S, Ichishima K, Ehara T. Regulation of extracellular UTP-activated Cl- current by P2Y-PLC-PKC signaling and ATP hydrolysis in mouse ventricular myocytes. J Physiol Sci 2007; 57:85-94. [PMID: 17291397 DOI: 10.2170/physiolsci.rp011406] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Accepted: 02/08/2007] [Indexed: 11/05/2022]
Abstract
The intracellular signaling pathways responsible for extracellualr uridine-5'-triphosphate (UTPo)-induced chloride (Cl-) currents (I(Cl.UTP)) were studied in mouse ventricular myocytes with the whole-cell clamp technique. UTPo (0.1 to 100 microM) activated a whole-cell current that showed a time-independent activation, a linear current-voltage relationship in symmetrical Cl- solutions, an anion selectivity of Cl- > iodide > aspartate, and an inhibition by a thiazolidinone-derived specific inhibitor (CFTR(inh)-172, 10 microM) of cystic fibrosis transmembrane conductance regulator (CFTR), but not by a disulfonic stilbene derivative (DIDS, 100 microM), these properties matching those of CFTR Cl- channels. The potency order of nucleotides for an activation of the Cl- current was UTP = ATP > uridine-5'-diphosphate (UDP) = ADP. Suramin (100 microM), a P2Y receptor antagonist, strongly inhibited the UTPo -activation of the Cl- current, whereas pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS, 100 microM), another P2Y receptor antagonist, induced little inhibition of I(Cl.UTP). The activation of I(Cl.UTP) was sensitive to protein kinase C (PKC) inhibitor, phospholipase C (PLC) inhibitor, intracellular GDPbetaS (nonhydrolyzable GDP analogue) or anti-Gq/11 antibody. UTPo failed to activate the Cl- current when the cells were dialyzed with nonhydrolyzable ATP analogues (ATPS or AMP-PNP) without ATP, suggesting that ATP hydrolysis is a prerequisite for the current activation. I(Cl.UTP) was persistently activated with a mixture of ATPgammaS + ATP in the pipette, suggesting the involvement of phosphorylation reaction in the current activation process. Our results strongly suggest that I(Cl.UTP) is due to the activation of CFTR Cl- channels through Gq/11-coupled P2Y2 receptor-PLC-PKC signaling and ATP hydrolysis in mouse heart.
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Affiliation(s)
- Shintaro Yamamoto
- Department of Physiology, Saga University Faculty of Medicine, Saga, 849-8501 Japan.
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468
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Di Virgilio F. Purinergic signalling in the immune system. A brief update. Purinergic Signal 2007; 3:1-3. [PMID: 18404413 PMCID: PMC2096765 DOI: 10.1007/s11302-006-9048-5] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Accepted: 10/10/2006] [Indexed: 12/03/2022] Open
Affiliation(s)
- Francesco Di Virgilio
- Department of Experimental and Diagnostic Medicine, Section of General Pathology, and Interdisciplinary Center for the Study of Inflammation, University of Ferrara, Via Borsari 46, 44100, Ferrara, Italy,
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469
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Pedrazza EL, Riboldi GP, Pereira GS, Izquierdo I, Bonan CD. Habituation to an open field alters ecto-nucleotidase activities in rat hippocampal synaptosomes. Neurosci Lett 2007; 413:21-4. [PMID: 17166665 DOI: 10.1016/j.neulet.2006.11.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2006] [Revised: 11/09/2006] [Accepted: 11/12/2006] [Indexed: 11/20/2022]
Abstract
ATP and adenosine may play a role in the mechanisms of synaptic plasticity and memory formation. Previous studies have shown that ecto-nucleotidase activities are altered during memory consolidation of an aversive task named step-down inhibitory avoidance. Here we investigate ecto-nucleotidase activities in hippocampal synaptosomes of rats submitted to training and test sessions of habituation to open field, which is one of the most elementary forms of learning. There were no significant alterations on ATP, ADP and AMP hydrolysis immediately after the training session. However, immediately after the test session (0min), there was a significant increase of ATP hydrolysis (61%), but not of ADP and AMP hydrolysis. Sixty minutes after the test session, a significant increase of NTPDase (75% and 60.5% for ATP and ADP hydrolysis, respectively) and ecto-5'-nucleotidase (40%) activities was observed. This study reveals the involvement of ecto-nucleotidase activities in different learning paradigms during memory processing.
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Affiliation(s)
- Eduardo Luiz Pedrazza
- Laboratório de Neuroquímica e Psicofarmacologia, Departamento de Biologia Celular e Molecular, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul. Avenida Ipiranga, 6681, 90619-900 Porto Alegre, RS, Brazil
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470
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Vlajkovic SM, Wang CJH, Soeller C, Zimmermann H, Thorne PR, Housley GD. Activation-dependent trafficking of NTPDase2 in Chinese hamster ovary cells. Int J Biochem Cell Biol 2007; 39:810-7. [PMID: 17307380 DOI: 10.1016/j.biocel.2007.01.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Revised: 12/18/2006] [Accepted: 01/02/2007] [Indexed: 11/28/2022]
Abstract
Membrane-bound NTPDase2 is a member of the ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase) enzyme family involved in the regulation of P2 receptor signaling. NTPDase2 has broad substrate specificity for extracellular nucleotides, but hydrolyses nucleoside 5'-triphosphates with high preference over nucleoside 5'-diphosphates. In this study, we have sought to determine how enzyme substrates acting on P2 receptors affect intracellular NTPDase2 trafficking. To achieve this, Chinese hamster ovary (CHO) cells were transiently transfected with rat-specific NTPDase2 cDNA tagged with green fluorescent protein (GFP), to allow direct visualisation of subcellular localisation and trafficking of NTPDase2. Cells were superfused with NTPDase2 substrates (ATP and UTP) and synthetic nucleotide analogues (ATPgammaS and ADPbetaS), and confocal image stacks were acquired at regular time intervals. NTPDase2 incorporation into the plasma membrane was determined by comparative analysis of fluorescence intensity in the cytosolic and membrane compartments. GFP-tagged NTPDase2 was fully functional and ATP and ATPgammaS induced membrane incorporation of GFP-NTPDase2 from putative intracellular stores, whilst UTP and ADPbetaS were ineffective. The increased ATP hydrolysis rate correlated with increased NTPDase2 trafficking to the plasma membrane. ATP-induced NTPDase2 trafficking was mediated by activation of endogenous P2X receptors involving Ca2+ entry rather than by P2Y receptor-induced release of Ca2+ from intracellular stores. Our results suggest that P2X receptor activation stimulates insertion of latent NTPDase2 into the plasma membrane. The increase in surface-located NTPDase2 may reflect a regulatory mechanism counteracting excessive stimulation and desensitisation of P2 receptors.
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Affiliation(s)
- Srdjan M Vlajkovic
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
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471
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Yegutkin GG, Samburski SS, Mortensen SP, Jalkanen S, González-Alonso J. Intravascular ADP and soluble nucleotidases contribute to acute prothrombotic state during vigorous exercise in humans. J Physiol 2007; 579:553-64. [PMID: 17204504 PMCID: PMC2075398 DOI: 10.1113/jphysiol.2006.119453] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Extracellular ATP and ADP trigger vasodilatatory and prothrombotic signalling events in the vasculature. Here, we tested the hypothesis that nucleotide turnover is activated in the bloodstream of exercising humans thus contributing to the enhanced platelet reactivity and haemostasis. Right atrial, arterial and venous blood samples were collected from endurance-trained athletes at rest, during submaximal and maximal cycle ergometer exercise, and after early recovery. ATP-specific bioluminescent assay, together with high-performance liquid chromatographic analysis, revealed that plasma ATP and ADP concentrations increased up to 2.5-fold during maximal exercise. Subsequent flow cytometric analysis showed that plasma from exercising subjects significantly up-regulated the surface expression of P-selectin in human platelets and these prothrombotic effects were diminished after scavenging plasma nucleotides with exogenous apyrase. Next, using thin layer chromatographic assays with [gamma-(32)P]ATP and (3)H/(14)C-labelled nucleotides, we showed that two soluble nucleotide-inactivating enzymes, nucleotide pyrophosphatase/phosphodiesterase and nucleoside triphosphate diphosphohydrolase, constitutively circulate in human bloodstream. Strikingly, serum nucleotide pyrophosphatase and hydrolase activities rose during maximal exercise by 20-25 and 80-100%, respectively, and then declined after 30 min recovery. Likewise, soluble nucleotidases were transiently up-regulated in the venous blood of sedentary subjects during exhaustive exercise. Human serum also contains 5'-nucleotidase, adenylate kinase and nucleoside diphosphate (NDP) kinase; however, these activities remain unchanged during exercise. In conclusion, intravascular ADP significantly augments platelet activity during strenuous exercise and these prothrombotic responses are counteracted by concurrent release of soluble nucleotide-inactivating enzymes. These findings provide a novel insight into the mechanisms underlying the enhanced risk of occlusive thrombus formation under exercising conditions.
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Affiliation(s)
- Gennady G Yegutkin
- MediCity Research Laboratory, University of Turku, National Public Health Institute, Turku, Finland.
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472
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Abstract
Measurement of visceral sensitivity in animals is mainly based on 'pseudoaffective' responses, which are brain stem reflexes. For example, in female, but not male rats, acute partial restraint stress induces hypersensitivity to colorectal distension. Mucosal mast cell density increases in rats after nematode infection or maternal deprivation, and both also induce colon hypersensitivity. Significantly, the proximity between nerves and mast cells has been found to be increased in adult rats submitted to maternal deprivation. Protease activation of the proteinase-activated receptor-2 also increases visceral nociception in rats, suggesting that an increase in paracellular permeability may be the primum movens in several animal models of visceral hypersensitivity. Accumulating evidence suggests that sensitization of visceral afferents is not restricted to the presumed nociceptor population, suggesting that most of the mechanosensitive afferent population can contribute to visceral discomfort and pain. Other inflammation-produced changes (e.g. subunit composition of purine-gated P2X channels) in visceral sensory neurones may also contribute to visceral hypersensitivity. This article discusses use of in vivo strategies (and transgenic mouse models) to reveal putative roles in mechanosensitivity and sensitization for molecules not previously considered to have mechanosensory functions.
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Affiliation(s)
- J Fioramonti
- Neurogastroenterology and Nutrition Unit, INRA, Toulouse cedex, France.
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473
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Volonté C, Amadio S, D'Ambrosi N, Colpi M, Burnstock G. P2 receptor web: Complexity and fine-tuning. Pharmacol Ther 2006; 112:264-80. [PMID: 16780954 DOI: 10.1016/j.pharmthera.2005.04.012] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2005] [Accepted: 04/12/2005] [Indexed: 12/25/2022]
Abstract
The present review offers a new perspective on a family of receptors, termed P2 receptors, specific for nucleoside tri- and diphosphates of purines/pyrimidines. We emphasize here that while decoding the inputs of various related extracellular ligands, P2 receptors are a clear example of increasing biological complexity. They are represented by 7 ionotropic P2X and 8 metabotropic P2Y receptors; they have very heterogeneous ligands and binding characteristics, molecular properties, transduction mechanisms, cellular localization and protein-protein interactions. While the reason for this sophistication is unknown, a few compelling issues emerge while looking at such a rich variety. We ask, for instance, why so many different receptor subtypes are necessary for triggering biological properties and functions, and if these receptors are more than the sum of their single entities. A first possibility is that newly synthesized P2 proteins are casually located on the cell surface (stochastic hypothesis). Alternatively, distinct subunits are engaged on different cell phenotypes by genetic control (genetic determinism) and/or selective recruitment under physiopathological conditions and epigenetic stimuli (epigenetic determinism). Nevertheless, an appropriate way to both dissect the vast biological scenario and molecular complexity among P2 receptors and to integrate and upgrade their assortment is to regard them as a "combinatorial receptor web", that is, a dynamic architecture of P2 proteins demonstrating economic efficiency and involving a process of "fine-tuning", a mechanism which endorses the dynamic nature of all biological reactions. In the present analysis, we stimulate a scientific query about what contributes to such a vast P2 receptor sophistication.
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Affiliation(s)
- Cinzia Volonté
- Santa Lucia Foundation/CNR, Via Del Fosso di Fiorano 64, 00143 Roma, Italy.
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474
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Honore P, Donnelly-Roberts D, Namovic MT, Hsieh G, Zhu CZ, Mikusa JP, Hernandez G, Zhong C, Gauvin DM, Chandran P, Harris R, Medrano AP, Carroll W, Marsh K, Sullivan JP, Faltynek CR, Jarvis MF. A-740003 [N-(1-{[(cyanoimino)(5-quinolinylamino) methyl]amino}-2,2-dimethylpropyl)-2-(3,4-dimethoxyphenyl)acetamide], a novel and selective P2X7 receptor antagonist, dose-dependently reduces neuropathic pain in the rat. J Pharmacol Exp Ther 2006; 319:1376-85. [PMID: 16982702 DOI: 10.1124/jpet.106.111559] [Citation(s) in RCA: 321] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
ATP-sensitive P2X(7) receptors are localized on cells of immunological origin including glial cells in the central nervous system. Activation of P2X(7) receptors leads to rapid changes in intracellular calcium concentrations, release of the proinflammatory cytokine interleukin-1beta (IL-1beta), and following prolonged agonist exposure, cytolytic plasma membrane pore formation. P2X(7) knockout mice show reduced inflammation as well as decreased nociceptive sensitivity following peripheral nerve injury. A-740003 (N-(1-{[(cyanoimino)(5-quinolinylamino) methyl] amino}-2,2-dimethylpropyl)-2-(3,4-dimethoxyphenyl)acetamide) is a novel competitive antagonist of P2X(7) receptors (IC(50) values = 40 nM for human and 18 nM for rat) as measured by agonist-stimulated changes in intracellular calcium concentrations. A-740003 showed weak or no activity (IC(50) > 10 muM) at other P2 receptors and an array of other neurotransmitter and peptide receptors, ion channels, reuptake sites, and enzymes. A-740003 potently blocked agonist-evoked IL-1beta release (IC(50) = 156 nM) and pore formation (IC(50) = 92 nM) in differentiated human THP-1 cells. Systemic administration of A-740003 produced dose-dependent antinociception in a spinal nerve ligation model (ED(50) = 19 mg/kg i.p.) in the rat. A-740003 also attenuated tactile allodynia in two other models of neuropathic pain, chronic constriction injury of the sciatic nerve and vincristine-induced neuropathy. In addition, A-740003 effectively reduced thermal hyperalgesia observed following intraplantar administration of carrageenan or complete Freund's adjuvant (ED(50) = 38-54 mg/kg i.p.). A-740003 was ineffective in attenuating acute thermal nociception in normal rats and did not alter motor performance at analgesic doses. These data demonstrate that selective blockade of P2X(7) receptors in vivo produces significant antinociception in animal models of neuropathic and inflammatory pain.
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Affiliation(s)
- Prisca Honore
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois 60064, USA
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475
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Abbracchio MP, Burnstock G, Boeynaems JM, Barnard EA, Boyer JL, Kennedy C, Knight GE, Fumagalli M, Gachet C, Jacobson KA, Weisman GA. International Union of Pharmacology LVIII: update on the P2Y G protein-coupled nucleotide receptors: from molecular mechanisms and pathophysiology to therapy. Pharmacol Rev 2006; 58:281-341. [PMID: 16968944 PMCID: PMC3471216 DOI: 10.1124/pr.58.3.3] [Citation(s) in RCA: 987] [Impact Index Per Article: 54.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
There have been many advances in our knowledge about different aspects of P2Y receptor signaling since the last review published by our International Union of Pharmacology subcommittee. More receptor subtypes have been cloned and characterized and most orphan receptors de-orphanized, so that it is now possible to provide a basis for a future subdivision of P2Y receptor subtypes. More is known about the functional elements of the P2Y receptor molecules and the signaling pathways involved, including interactions with ion channels. There have been substantial developments in the design of selective agonists and antagonists to some of the P2Y receptor subtypes. There are new findings about the mechanisms underlying nucleotide release and ectoenzymatic nucleotide breakdown. Interactions between P2Y receptors and receptors to other signaling molecules have been explored as well as P2Y-mediated control of gene transcription. The distribution and roles of P2Y receptor subtypes in many different cell types are better understood and P2Y receptor-related compounds are being explored for therapeutic purposes. These and other advances are discussed in the present review.
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Affiliation(s)
- Maria P Abbracchio
- Department of Pharmacological Sciences, University of Milan, Milan, Italy
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476
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Olteanu D, Hovater MB, Schwiebert EM. Intraluminal autocrine purinergic signaling within cysts: implications for the progression of diseases that involve encapsulated cyst formation. Am J Physiol Renal Physiol 2006; 292:F11-4. [PMID: 16940560 DOI: 10.1152/ajprenal.00291.2006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
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477
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Koshimizu TA, Tsujimoto G. Functional role of spliced cytoplasmic tails in P2X2-receptor-mediated cellular signaling. J Pharmacol Sci 2006; 101:261-6. [PMID: 16891773 DOI: 10.1254/jphs.cpj06012x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
P2X receptors belong to a unique family of ligand-gated channels in terms of their molecular architecture, in which the channel subunit has two transmembrane alpha-helixes with a large extracellular loop keeping amino- and carboxy-termini in the cytoplasm. Post-transcriptional modifications of P2X receptors could diversify cellular responsiveness induced by extracellular ATP in anterior pituitary cells and other cell types. Recently, we found a spliced variant P2X2 transcript, termed P2X2e, in mouse pituitary. The P2X2e has a shorter cytoplasmic carboxy-terminal tail than those of full-length P2X2a or splice variant P2X2b subunits. Although ATP induced rapid responses in all homomeric P2X2 channels, the current induced by P2X2e declined significantly faster than those by P2X2a or P2X2b. In this article, we summarize functional alterations of P2X2 receptors after splicing reactions. Combinations of different P2X2 subunit carboxy-termini to form homomeric and heteromeric channels could be a molecular mechanism for promoting functional diversities of ATP-induced cellular signals.
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Affiliation(s)
- Taka-aki Koshimizu
- Department of Genomic Drug Discovery Science, Graduate School of Pharmaceutical Sciences, Kyoto University, Japan
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478
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Trang T, Beggs S, Salter MW. Purinoceptors in microglia and neuropathic pain. Pflugers Arch 2006; 452:645-52. [PMID: 16767466 DOI: 10.1007/s00424-006-0074-5] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2006] [Accepted: 03/10/2006] [Indexed: 01/23/2023]
Abstract
Emerging evidence indicates that microglia play a critical role in the pathogenesis of neuropathic pain, a debilitating chronic pain condition that can occur after peripheral nerve damage caused by disease, infection, or physical injury. Microglia are immunocompetent cells of the central nervous system and express various ionotropic P2X and metabotropic P2Y purinoceptors. After injury to a peripheral nerve, microglia in the spinal cord become activated and upregulate expression of the P2X4 receptor. Recent findings suggest that activation of P2X4 receptors evokes release of brain-derived neurotrophic factor from microglia and that this mediates microglia-neuron signaling leading to pain hypersensitivity. Thus, P2X4 receptors and the intracellular signaling mediators in microglia are promising therapeutic targets for the development of novel pharmacological agents in the management of neuropathic pain.
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Affiliation(s)
- Tuan Trang
- University of Toronto Centre for the Study of Pain, Programmes in Brain and Behaviour and Cell Biology, Hospital for Sick Children, Toronto, Ontario, M5G 1X8, Canada
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