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Schubert C, Schulz K, Träger S, Plath AL, Omriouate A, Rosenkranz SC, Morellini F, Friese MA, Hirnet D. Neuronal Adenosine A1 Receptor is Critical for Olfactory Function but Unable to Attenuate Olfactory Dysfunction in Neuroinflammation. Front Cell Neurosci 2022; 16:912030. [PMID: 35846561 PMCID: PMC9279574 DOI: 10.3389/fncel.2022.912030] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Accepted: 06/08/2022] [Indexed: 11/13/2022] Open
Abstract
Adenine nucleotides, such as adenosine triphosphate (ATP), adenosine diphosphate (ADP), as well as the nucleoside adenosine are important modulators of neuronal function by engaging P1 and P2 purinergic receptors. In mitral cells, signaling of the G protein-coupled P1 receptor adenosine 1 receptor (A1R) affects the olfactory sensory pathway by regulating high voltage-activated calcium channels and two-pore domain potassium (K2P) channels. The inflammation of the central nervous system (CNS) impairs the olfactory function and gives rise to large amounts of extracellular ATP and adenosine, which act as pro-inflammatory and anti-inflammatory mediators, respectively. However, it is unclear whether neuronal A1R in the olfactory bulb modulates the sensory function and how this is impacted by inflammation. Here, we show that signaling via neuronal A1R is important for the physiological olfactory function, while it cannot counteract inflammation-induced hyperexcitability and olfactory deficit. Using neuron-specific A1R-deficient mice in patch-clamp recordings, we found that adenosine modulates spontaneous dendro-dendritic signaling in mitral and granule cells via A1R. Furthermore, neuronal A1R deficiency resulted in olfactory dysfunction in two separate olfactory tests. In mice with experimental autoimmune encephalomyelitis (EAE), we detected immune cell infiltration and microglia activation in the olfactory bulb as well as hyperexcitability of mitral cells and olfactory dysfunction. However, neuron-specific A1R activity was unable to attenuate glutamate excitotoxicity in the primary olfactory bulb neurons in vitro or EAE-induced olfactory dysfunction and disease severity in vivo. Together, we demonstrate that A1R modulates the dendro-dendritic inhibition (DDI) at the site of mitral and granule cells and impacts the processing of the olfactory sensory information, while A1R activity was unable to counteract inflammation-induced hyperexcitability.
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Affiliation(s)
- Charlotte Schubert
- Institute of Neuroimmunology and Multiple Sclerosis (INIMS), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Kristina Schulz
- Division of Neurophysiology, Institute of Cell and Systems Biology of Animals, University of Hamburg, Hamburg, Germany
| | - Simone Träger
- Institute of Neuroimmunology and Multiple Sclerosis (INIMS), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Anna-Lena Plath
- Research Group Behavioral Biology, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Asina Omriouate
- Research Group Behavioral Biology, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sina C. Rosenkranz
- Institute of Neuroimmunology and Multiple Sclerosis (INIMS), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Fabio Morellini
- Research Group Behavioral Biology, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Manuel A. Friese
- Institute of Neuroimmunology and Multiple Sclerosis (INIMS), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- *Correspondence: Manuel A. Friese,
| | - Daniela Hirnet
- Division of Neurophysiology, Institute of Cell and Systems Biology of Animals, University of Hamburg, Hamburg, Germany
- Daniela Hirnet,
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Schulz K, Rotermund N, Grzelka K, Benz J, Lohr C, Hirnet D. Adenosine A 1 Receptor-Mediated Attenuation of Reciprocal Dendro-Dendritic Inhibition in the Mouse Olfactory Bulb. Front Cell Neurosci 2018; 11:435. [PMID: 29379418 PMCID: PMC5775233 DOI: 10.3389/fncel.2017.00435] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 12/26/2017] [Indexed: 12/14/2022] Open
Abstract
It is well described that A1 adenosine receptors inhibit synaptic transmission at excitatory synapses in the brain, but the effect of adenosine on reciprocal synapses has not been studied so far. In the olfactory bulb, the majority of synapses are reciprocal dendro-dendritic synapses mediating recurrent inhibition. We studied the effect of A1 receptor activation on recurrent dendro-dendritic inhibition in mitral cells using whole-cell patch-clamp recordings. Adenosine reduced dendro-dendritic inhibition in wild-type, but not in A1 receptor knock-out mice. Both NMDA receptor-mediated and AMPA receptor-mediated dendro-dendritic inhibition were attenuated by adenosine, indicating that reciprocal synapses between mitral cells and granule cells as well as parvalbumin interneurons were targeted by A1 receptors. Adenosine reduced glutamatergic self-excitation and inhibited N-type and P/Q-type calcium currents, but not L-type calcium currents in mitral cells. Attenuated glutamate release, due to A1 receptor-mediated calcium channel inhibition, resulted in impaired dendro-dendritic inhibition. In behavioral tests we tested the ability of wild-type and A1 receptor knock-out mice to find a hidden piece of food. Knock-out mice were significantly faster in locating the food. Our results indicate that A1 adenosine receptors attenuates dendro-dendritic reciprocal inhibition and suggest that they affect odor information processing.
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Affiliation(s)
- Kristina Schulz
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Natalie Rotermund
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Katarzyna Grzelka
- Department of Physiology and Pathophysiology, Medical University of Warsaw, Warsaw, Poland
| | - Jan Benz
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Christian Lohr
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Daniela Hirnet
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Hamburg, Germany
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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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4
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Abstract
Adenine-based purines, such as adenosine and ATP, are ubiquitous molecules that, in addition to their roles in metabolism, act as modulators of neurotransmitter release through activation of presynaptic P1 purinoceptors or adenosine receptors (activated by adenosine) and P2 receptors (activated by nucleotides). Of the latter, the P2Y receptors are G protein-coupled, whereas the P2X receptors are ligand-gated ion channels and not covered in this review.
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MESH Headings
- Adenosine/pharmacology
- Adenosine/physiology
- Animals
- Humans
- Neurotransmitter Agents/metabolism
- Purines/metabolism
- Receptor, Adenosine A1/drug effects
- Receptor, Adenosine A1/metabolism
- Receptors, Adenosine A2/drug effects
- Receptors, Adenosine A2/metabolism
- Receptors, Presynaptic/drug effects
- Receptors, Presynaptic/physiology
- Receptors, Purinergic P1/drug effects
- Receptors, Purinergic P1/physiology
- Receptors, Purinergic P2/drug effects
- Receptors, Purinergic P2/physiology
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Affiliation(s)
- Jorge Gonçalves
- Department of Pharmacology, University of Porto, Porto, Portugal.
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Sichardt K, Nieber K. Adenosine A(1) receptor: Functional receptor-receptor interactions in the brain. Purinergic Signal 2007; 3:285-98. [PMID: 18404442 PMCID: PMC2072922 DOI: 10.1007/s11302-007-9065-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Accepted: 07/24/2007] [Indexed: 12/20/2022] Open
Abstract
Over the past decade, many lines of investigation have shown that receptor-mediated signaling exhibits greater diversity than previously appreciated. Signal diversity arises from numerous factors, which include the formation of receptor dimers and interplay between different receptors. Using adenosine A1 receptors as a paradigm of G protein-coupled receptors, this review focuses on how receptor-receptor interactions may contribute to regulation of the synaptic transmission within the central nervous system. The interactions with metabotropic dopamine, adenosine A2A, A3, neuropeptide Y, and purinergic P2Y1 receptors will be described in the first part. The second part deals with interactions between A1Rs and ionotropic receptors, especially GABAA, NMDA, and P2X receptors as well as ATP-sensitive K+ channels. Finally, the review will discuss new approaches towards treating neurological disorders.
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Affiliation(s)
- Kathrin Sichardt
- Institute of Pharmacy, University of Leipzig, Talstr. 33, 04103 Leipzig, Germany
| | - Karen Nieber
- Institute of Pharmacy, University of Leipzig, Talstr. 33, 04103 Leipzig, Germany
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Schmidt AP, Lara DR, Souza DO. Proposal of a guanine-based purinergic system in the mammalian central nervous system. Pharmacol Ther 2007; 116:401-16. [PMID: 17884172 DOI: 10.1016/j.pharmthera.2007.07.004] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2007] [Accepted: 07/30/2007] [Indexed: 01/06/2023]
Abstract
Guanine-based purines have been traditionally studied as modulators of intracellular processes, mainly G-protein activity. However, they also exert several extracellular effects not related to G proteins, including modulation of glutamatergic activity, trophic effects on neural cells, and behavioral effects. In this article, the putative roles of guanine-based purines on the nervous system are reviewed, and we propose a specific guanine-based purinergic system in addition to the well-characterized adenine-based purinergic system. Current evidence suggest that guanine-based purines modulate glutamatergic parameters, such as glutamate uptake by astrocytes and synaptic vesicles, seizures induced by glutamatergic agents, response to ischemia and excitotoxicity, and are able to affect learning, memory and anxiety. Additionally, guanine-based purines have important trophic functions affecting the development, structure, or maintenance of neural cells. Although studies addressing the mechanism of action (receptors and second messenger systems) of guanine-based purines are still insufficient, these findings point to the guanine-based purines (nucleotides and guanosine) as potential new targets for neuroprotection and neuromodulation.
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Affiliation(s)
- André P Schmidt
- Departamento de Bioquímica, ICBS, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
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Ghildyal P, Palani D, Manchanda R. Post- and prejunctional consequences of ecto-ATPase inhibition: electrical and contractile studies in guinea-pig vas deferens. J Physiol 2006; 575:469-80. [PMID: 16675493 PMCID: PMC1819469 DOI: 10.1113/jphysiol.2006.109678] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
At sites of purinergic neurotransmission, synaptic ecto-ATPase is believed to limit the actions of ATP following its neural release. However, details of the modulation by this enzyme of the ATP-mediated conductance change and the possible mechanisms mediating this modulation remain unelucidated. We have addressed these issues by studying the effect of ARL 67156, a selective ecto-ATPase inhibitor, on ATP-mediated electrical and contractile activity in the sympathetically innervated guinea-pig vas deferens. ARL 67156 at 100 mum significantly potentiated the amplitude of spontaneous excitatory junction potentials (SEJPs) by 81.1% (P < 0.01) and prolonged their time courses (rise time by 49.7%, decay time constant by 38.2%; P < 0.01). Moreover, the frequency of occurrence of SEJPs was strikingly increased (from 0.28 +/- 0.13 to 0.90 +/- 0.26 Hz; P < 0.01), indicating an additional, primarily presynaptic, effect of ecto-ATPase inhibition. The frequency of occurrence of discrete events (DEs), which represent nerve stimulation-evoked quantal release of neurotransmitter, was also increased ( approximately 6-fold; P < 0.01), along with the appearance of DEs at previously 'silent' latencies. Purinergic contractions of the vas deferens were potentiated significantly (P < 0.01) by ARL 67156; these potentiated contractions were suppressed by the A1 agonist adenosine (P < 0.01) but left unaffected by the A1 antagonist 8-phenyltheophylline (8-PT). Our results indicate (i) that ecto-ATPase activity, in addition to modulating the ATP-mediated postjunctional conductance change, may regulate transmitter release prejunctionally under physiological conditions, and (ii) that the prejunctional regulation may be mediated primarily via presynaptic P2X, rather than A1, receptors.
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Affiliation(s)
- P Ghildyal
- Biomedical Engineering Group, School of Biosciences and Bioengineering, Indian Institute of Technology--Bombay, Mumbai 400076, India
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Borges E, Cognato GDP, Vuaden FC, Bogo MR, Fauth MDG, Bonan CD, Dias RD. Nucleotidase activities in membrane preparations of nervous ganglia and digestive gland of the snail Helix aspersa. Comp Biochem Physiol B Biochem Mol Biol 2005; 137:297-307. [PMID: 15050517 DOI: 10.1016/j.cbpc.2003.11.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2003] [Revised: 11/20/2003] [Accepted: 11/21/2003] [Indexed: 11/24/2022]
Abstract
Nucleotide-metabolizing enzymes play an important role in the regulation of nucleotide levels. In the present report, we demonstrated an enzyme activity with different kinetic properties in membrane preparations of the nervous ganglia and digestive gland from Helix aspersa. ATPase and ADPase activities were dependent on Ca2+ and Mg2+ with pH optima approximately 7.2 and between 6.0 and 8.0 in digestive gland and nervous ganglia, respectively. The enzyme activities present in membrane preparations of these tissues preferentially hydrolyzed triphosphate nucleotides. In nervous ganglia, the enzyme was insensitive to the classical ATPases inhibitors. In contrast, in digestive gland, N-ethylmaleimide (NEM) produced 45% inhibition of Ca(2+)-ATP hydrolysis. Sodium azide, at 100 microM and 20 mM, inhibited Mg(2+)-ATP hydrolysis by 36% and 55% in digestive gland, respectively. The presence of nucleotide-metabolizing enzymes in these tissues may be important for the modulation of nucleotide and nucleoside levels, controlling their actions on specific purinoceptors in these species.
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Affiliation(s)
- Eliane Borges
- Departamento de Ciências Fisiológicas, Faculdade de Biociências, Laboratório de Pesquisa Bioquímica, Pontifícia Universidade Católica do Rio Grande do Sul, Avenida Ipiranga, 6681, Caixa postal 1429, 90619-900, Porto Alegre, RS, Brazil
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9
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Matsuoka I, Ohkubo S. ATP- and adenosine-mediated signaling in the central nervous system: adenosine receptor activation by ATP through rapid and localized generation of adenosine by ecto-nucleotidases. J Pharmacol Sci 2004; 94:95-9. [PMID: 14978343 DOI: 10.1254/jphs.94.95] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Extracellular ATP is now recognized as a neurotransmitter or neuromodilator in the nervous system, producing diverse physiological effects by activating multiple P2 receptors. Although P2-receptor signaling is terminated by hydrolysis of ATP by the ecto-nucleotidase cascade, such a metabolic step leads to adenosine generation, thereby initiating adenosine (P1)-receptor activation. Because most cells and tissues co-express P1 and P2 receptors, ecto-nucleotidase on target tissues, especially enzymes catalyzing adenosine formation, are determinants of the cellular response to ATP. Ecto-5'-nucleotidase (E-5'-NT) has been considered to play a principal role in conversion of AMP to adenosine. In addition to E-5'-NT, we have recently demonstrated that ecto-alkaline phosphatase is also involved in ATP-induced P1-receptor activation through a rapid and localized adenosine production on the membrane surface. In this minireview, we describe the pharmacological profile of ecto-nucleotidase-dependent P1-receptor activation by ATP and molecular bases of preferential delivery of metabolically generated adenosine to P1 receptors. Several lines of evidence suggest that the close association between ecto-nucleotidases and P1 receptors may constitute a functional receptor for extracellular ATP, and some physiological responses to ATP would occur through this mechanism.
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Affiliation(s)
- Isao Matsuoka
- Department of Pharmacology, Fukushima Medical University School of Medicine, Japan.
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10
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Abstract
Neurons of the central nervous system (CNS) are endowed with ATP-sensitive receptors belonging to the P2X (ligand-gated cationic channels) and P2Y (G protein-coupled receptors) types. Whereas a number of P2X receptors mediate fast synaptic responses to the transmitter ATP, P2Y receptors mediate either slow changes of the membrane potential in response to non-synaptically released ATP or the interaction with receptors for other transmitters. To date seven P2X and seven P2Y receptors of human origin have been molecularly identified and functionally characterized. P2X subunits may occur as homooligomers or as heterooligomeric assemblies of more than one subunit. P2X(7) subunits do not form heterooligomeric assemblies and are unique in mediating apoptosis and necrosis of glial cells and possibly also of neurons. The P2X(2), P2X(4), P2X(4)/P2X(6) and P2Y(1) receptors appear to be the predominant neuronal types. The localisation of these receptors may be at the somato-dendritic region (postsynaptic) or at the nerve terminals (presynaptic). Postsynaptic P2 receptors appear to be mostly excitatory, while presynaptic P2 receptors may be either excitatory (P2X) or inhibitory (P2Y). Since in the CNS the stimulation of a single neuron may activate multiple networks, a concomitant stimulation of facilitatory and inhibitory circuits as a result of ATP release is also possible. Finally, the enzymatic degradation of ATP may lead to the local generation of adenosine which can modulate via A(1) or A(2A) receptor-activation the ATP effect.
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Affiliation(s)
- Peter Illes
- Rudolf-Boehm-Institute of Pharmacology, University of Leipzig, Haertelstrasse 16-18, 04107 Leipzig, Germany.
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11
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Ribeiro JA, Lobo MGB, Sebastião AM. Endogenous adenosine modulation of 22Na uptake by rat brain synaptosomes. Neurochem Res 2003; 28:1591-5. [PMID: 14570405 DOI: 10.1023/a:1025638929136] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
To evaluate if endogenous extracellular adenosine influences sodium channel activity in nerve terminals, we investigated how manipulations of extracellular adenosine levels influence 22Na uptake by rat brain synaptosomes stimulated with veratridine (VT). To decrease extracellular adenosine levels, adenosine deaminase (ADA) that converts adenosine into an inactive metabolite was used. To increase extracellular adenosine levels, we used the adenosine deaminase inhibitor erythro-9(2-hydroxy-3-nonyl) adenine (EHNA), as well as the inhibitor of adenosine transport, nitrobenzylthioinosine (NBTI). ADA (0.1-5 U/ml) caused an excitatory effect on 22Na uptake stimulated by veratridine, which was abolished in the presence of the adenosine deaminase inhibitor erythro-9(2-hydroxy-3-nonyl) adenine (EHNA, 25 microM). Both the adenosine uptake inhibitor nitrobenzylthioinosine (NBTI, 1-10 microM) and the adenosine deaminase inhibitor EHNA (10-25 microM) inhibited 22Na uptake by rat brain synaptosomes. It is suggested that adenosine is tonically inhibiting sodium uptake by rat brain synaptosomes.
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12
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Matsuoka I, Ohkubo S, Kimura J, Uezono Y. Adenine nucleotide-induced activation of adenosine A(2B) receptors expressed in Xenopus laevis oocytes: involvement of a rapid and localized adenosine formation by ectonucleotidases. Mol Pharmacol 2002; 61:606-13. [PMID: 11854441 DOI: 10.1124/mol.61.3.606] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We recently demonstrated that extracellular ATP effectively activates adenosine (Ade) A(2B) receptors indirectly through a localized rapid conversion to Ade by ectonucleotidases on the membrane surface of C6Bu-1 rat glioma cells. These responses were observed even in the presence of adenosine deaminase (ADA). Here, we demonstrate that such responses indeed occur in A(2B) receptor-expressing Xenopus laevis oocytes, which possess endogenous ectonucleotidase activity. In oocytes coexpressing the A(2B) receptor and cystic fibrosis transmembrane conductance regulator (CFTR), Ade induced a concentration-dependent increase in a cyclic AMP-activated CFTR current, a response that was inhibited by the P1 antagonist xanthine-amine congener (XAC). A brief application of ATP and beta,gamma-methylene ATP (beta,gamma-MeATP) also induced the CFTR current in a manner similar to that seen with Ade. Among several nucleotide agonists, ADP, AMP, and adenosine-5'-O-(3-thio)triphosphate induced the CFTR current. Although adenine nucleotide-induced CFTR currents were inhibited by XAC, they were highly resistant to ADA treatment; 5 U/ml ADA was required for inhibition of adenine nucleotide-induced CFTR current, whereas 1 U/ml ADA was sufficient to abolish the Ade-induced response. In addition, the ecto-5'-nucleotidase inhibitor alpha,beta-methylene ADP markedly inhibited the beta,gamma-MeATP-induced response but not the Ade-induced one. These results support our hypothesis that adenine nucleotides are rapidly and locally converted into Ade on the membrane surface, resulting in the activation of A(2B) receptors.
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Affiliation(s)
- Isao Matsuoka
- Department of Pharmacology, School of Medicine, Fukushima Medical University, Fukushima, Japan.
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13
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García-Ayllón MS, Campoy FJ, Vidal CJ, Muñoz-Delgado E. Identification of inactive ecto-5'-nucleotidase in normal mouse muscle and its increased activity in dystrophic Lama2(dy) mice. J Neurosci Res 2001; 66:656-65. [PMID: 11746385 DOI: 10.1002/jnr.10014] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Ecto-5'-nucleotidase (eNT) activity and protein in normal (NM) and merosin-deficient dystrophic (DM) Lama2(dy) mice muscle were studied. eNT activity in DM was three- to four-fold that in NM. eNT in NM and DM displayed the same kinetic properties. Slot and Western blotting revealed that the immunoreactive protein was two to three times more abundant in control muscle, when NM and DM samples with the same eNT activity were compared, indicating that mouse muscle contains catalytically inactive eNT components. eNT activity and protein peaks coincided in sedimentation analyses, revealing that inactive eNT occurs as dimers. Most eNT activity and protein of NM bound to Lens culinaris (LCA) or Ricinus communis (RCA) agglutinins, but half of the activity and one-third of the protein bound to wheat germ agglutinin (WGA). Although WGA interaction did not permit full separation of inactive eNT, the results suggest that similar proportions of active species with and without WGA reactivity occur in mouse muscle, whereas a great fraction of the inactive eNT variants lack WGA reactivity. Because the level of eNT protein was little modified in DM, the higher eNT activity in dystrophic than in control muscle may result from misregulation in the synthesis of active and inactive eNT species or from conversion of inactive into active components.
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Affiliation(s)
- M S García-Ayllón
- Departamento de Bioquímica y Biología Molecular-A, Universidad de Murcia, Espinardo, Murcia, Spain
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Ruppelt A, Ma W, Borchardt K, Silberberg SD, Soto F. Genomic structure, developmental distribution and functional properties of the chicken P2X(5) receptor. J Neurochem 2001; 77:1256-65. [PMID: 11389176 DOI: 10.1046/j.1471-4159.2001.00348.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We report here the cloning of a chicken cDNA (402 aa) showing high sequence similarity to the previously cloned rat and human P2X(5) receptors (67 and 69%, respectively). The chicken P2X(5) subunit is encoded by a gene composed of 12 translated exons, which shows conserved genomic structure with mammalian P2X genes. In HEK-293 cells heterologously expressing chicken P2X(5) receptors, ATP activates a current that desensitizes in a way that is dependent on the presence of extracellular divalent cations. ATP and 2-methylthio ATP are equipotent agonists (EC(50) approximately 2 microM) and suramin and pyridoxal 5-phosphate-6-azophenyl-2',4'-disulfonic acid are potent antagonists. Additionally, reversal potential measurements indicate that chicken P2X(5) is permeable not only to cations but also to chloride (P(Cs+)/P(Cl-) approximately 1.9), as has been described for native P2X receptor mediated responses in embryonic chicken skeletal muscle. mRNA distribution of chicken P2X(5) was determined by in situ hybridization analysis in both whole embryos and on tissue slices of heart and skeletal muscle. Our results suggest that chicken P2X(5) receptors are expressed in developing muscle and might play a role in early muscle differentiation.
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Affiliation(s)
- A Ruppelt
- Max-Planck-Institut für experimentelle Medizin, Molekulare Biologie Neuronaler Signale, Göttingen, Germany
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Abstract
The endogenous mechanisms modulating ATP-induced dopamine release in the nucleus accumbens (NAc) were studied by microdialysis in freely moving rats. The ATP analog 2-Methylthio ATP (2-MeSATP) facilitated the release of dopamine in a manner sensitive to pertussis toxin and tetrodotoxin. It is suggested that G-protein-coupled P2Y receptors and voltage-gated sodium channels are involved in this process. N-methyl-D-aspartate (NMDA) applied in a concentration of 100 microM decreased the extracellular dopamine level, whereas 1 and 10 mM NMDA enhanced it. The endogenous agonist glutamate (10 microM) inhibited the basal and facilitated release of dopamine. Infusion with a combination of the ionotropic glutamate receptor antagonists (+/-)-3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), as well as with the metabotropic glutamate receptor antagonist (+/-)-alpha-methyl-4-carboxyphenylglycine (MCPG) increased the basal level of dopamine and potentiated the 2-MeSATP-facilitated dopamine release, suggesting an ATP-mediated glutamate release. The GABA(A) receptor antagonist bicuculline infused into the NAc also enhanced the basal level of dopamine; however, the application of 2-MeSATP in the presence of bicuculline caused an early decrease and a subsequent increase of dopamine release. The facilitatory phase of the 2-MeSATP effect was comparable with that measured in the absence of bicuculline. By contrast, when bicuculline was infused into the ventral tegmental area (VTA) it elevated the accumbal basal dopamine level and in addition facilitated the 2-MeSATP- and the glutamate-induced dopamine release above that measured in the absence of bicuculline. These results suggest that ATP in the NAc has a physiologically relevant function in modulating dopaminergic transmission depending on the mesolimbic neuronal activity. The first component of the ATP effect involves a direct stimulation of the terminals of VTA neurons, while the second inhibitory component involves a sequential activation of glutamate and, finally, via ionotropic and metabotropic glutamate receptors, of GABA neurons projecting to the VTA.
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Affiliation(s)
- U Krügel
- Rudolf Boehm Department of Pharmacology and Toxicology, University of Leipzig, Leipzig, Germany.
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16
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Cunha RA. Adenosine as a neuromodulator and as a homeostatic regulator in the nervous system: different roles, different sources and different receptors. Neurochem Int 2001; 38:107-25. [PMID: 11137880 DOI: 10.1016/s0197-0186(00)00034-6] [Citation(s) in RCA: 462] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Adenosine exerts two parallel modulatory roles in the CNS, acting as a homeostatic modulator and also as a neuromodulator at the synaptic level. We will present evidence to suggest that these two different modulatory roles are fulfilled by extracellular adenosine originated from different metabolic sources, and involve receptors with different sub-cellular localisation. It is widely accepted that adenosine is an inhibitory modulator in the CNS, a notion that stems from the preponderant role of inhibitory adenosine A(1) receptors in defining the homeostatic modulatory role of adenosine. However, we will review recent data that suggests that the synaptically localised neuromodulatory role of adenosine depend on a balanced activation of inhibitory A(1) receptors and mostly facilitatory A(2A) receptors. This balanced activation of A(1) and A(2A) adenosine receptors depends not only on the transient levels of extracellular adenosine, but also on the direct interaction between A(1) and A(2A) receptors, which control each other's action.
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Affiliation(s)
- R A Cunha
- Laboratory of Neurosciences, Faculty of Medicine, University of Lisbon, Portugal.
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Ohkubo S, Kumazawa K, Sagawa K, Kimura J, Matsuoka I. Beta,gamma-methylene ATP-induced cAMP formation in C6Bu-1 cells: involvement of local metabolism and subsequent stimulation of adenosine A2B receptor. J Neurochem 2001; 76:872-80. [PMID: 11158259 DOI: 10.1046/j.1471-4159.2001.00098.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The mechanism underlying beta,gamma-methylene ATP (beta,gamma-MeATP)-induced cAMP elevation was investigated in rat glioma C6Bu-1 cells. Beta,gamma-MeATP increased forskolin-stimulated cAMP formation in a manner sensitive to both the P1 antagonist xanthine amine congener (XAC) and the P2 antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS). Adenosine deaminase (ADA; 1 U/mL), which abolished the adenosine-induced response, did not eliminate the beta,gamma-MeATP-induced response. However, combination of ADA with alpha,beta-methylene ADP (alpha,beta-MeADP), an ecto-5'-nucleotidase inhibitor, blocked the beta,gamma-MeATP-induced response. AMP, the substrate for ecto-5'-nucleotidase, also induced cAMP formation in a manner sensitive to XAC and alpha,beta-MeADP inhibition. However, the AMP-induced response was not blocked by PPADS. HPLC analyses revealed that adenosine was generated from beta,gamma-MeATP and AMP. In addition, alpha,beta-MeADP inhibited the conversion of beta,gamma-MeATP and AMP to adenosine, whereas PPADS blocked adenosine formation from beta,gamma-MeATP but not from AMP. [3H]Adenosine generated from [3H]AMP was preserved on the cell surface environment even in the presence of ADA. The mRNAs for ecto-phosphodiesterase/pyrophosphatase 1 (EC 3.1.4.1), ecto-5'-nucleotidase (EC 3.1.3.5) and adenosine A2B receptor were detected by RT-PCR. These results suggest that C6Bu-1 cells possess ecto-enzymes converting beta,gamma-MeATP to adenosine, and the locally accumulated adenosine in this mechanism efficiently stimulates A2B receptors in a manner resistant to exogenous ADA.
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Affiliation(s)
- S Ohkubo
- Department of Pharmacology, School of Medicine, Fukushima Medical University, Fukushima, Japan
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18
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Ohkubo S, Kimura J, Matsuoka I. Ecto-alkaline phosphatase in NG108-15 cells : a key enzyme mediating P1 antagonist-sensitive ATP response. Br J Pharmacol 2000; 131:1667-72. [PMID: 11139445 PMCID: PMC1572508 DOI: 10.1038/sj.bjp.0703750] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2000] [Revised: 10/02/2000] [Accepted: 10/02/2000] [Indexed: 11/09/2022] Open
Abstract
We previously demonstrated that extracellular adenine nucleotides induced cyclic AMP elevation through local adenosine production at the membrane surface and subsequent activation of adenosine A(2A) receptors in NG108-15 cells. Furthermore, the adenosine formation was found to be mediated by an ecto-enzyme distinct from the ecto-5'-nucleotidase (CD73). In this study, we investigated the properties of the ecto-AMP phosphohydrolase activity in NG108-15 cells. NG108-15 cells hydrolyzed AMP to adenosine with the K:(M:) value of 18.8+/-2.2 microM and V(max) of 5.3+/-1.6 nmol min(-1) 10(6) cells(-1). This activity was suppressed at pH 6.5, but markedly increased at pH 8.5. The AMP hydrolysis was blocked by levamisole, an alkaline phosphatase (ALP) inhibitor. NG108-15 cells released orthophosphate from 2'- and 3'-AMP as well as from ribose-5-phosphate and ss-glycerophosphate, indicating that NG108-15 cells express ecto-ALP. The cyclic AMP accumulation induced by several adenine nucleotides was inhibited by levamisole, p-nitrophenylphosphate and ss-glycerophosphate, with a parallel decrease in the extracellular adenosine formation. Reverse transcriptase polymerase chain reaction analysis revealed that NG108-15 cells express mRNA for the tissue-nonspecific isozyme of ALP. These results demonstrate that AMP phosphohydrolase activity in NG108-15 cells is due to ecto-ALP, and suggest that this enzyme plays an essential role for the P1 antagonist-sensitive ATP-induced cyclic AMP accumulation in NG108-15 cells.
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Affiliation(s)
- Satoko Ohkubo
- Department of Pharmacology, School of Medicine, Fukushima Medical University, Hikarigaoka-1, Fukushima 960-1295, Japan
| | - Junko Kimura
- Department of Pharmacology, School of Medicine, Fukushima Medical University, Hikarigaoka-1, Fukushima 960-1295, Japan
| | - Isao Matsuoka
- Department of Pharmacology, School of Medicine, Fukushima Medical University, Hikarigaoka-1, Fukushima 960-1295, Japan
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Ohkubo S, Kimura J, Matsuoka I. Correlation between adenine nucleotide-induced cyclic AMP elevation and extracellular adenosine formation in NG108-15 cells. JAPANESE JOURNAL OF PHARMACOLOGY 2000; 84:325-33. [PMID: 11138734 DOI: 10.1254/jjp.84.325] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We previously demonstrated that extracellular adenine nucleotides induced cyclic AMP elevation in NG108-15 cells. This response was resistant to adenosine deaminase (ADA) and the ecto-5'-nucleotidase (CD73) inhibitor alpha,beta-methylene ADP (alpha,beta-MeADP), but was inhibited by both P1- and P2-receptor antagonists. In the present study, we investigated the relationship between adenine nucleotide-induced cyclic AMP elevation and extracellular adenosine formation. ATP, AMP and beta,gamma-methylene ATP (beta,gamma-MeATP) were time-dependently metabolized to adenosine in NG108-15 cells. Adenosine formations from ATP, AMP and beta,gamma-MeATP were not affected by alpha,beta-MeADP, but suppressed by the P2-receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS). A close correlation between extracellular adenosine formation and cyclic AMP increasing effects were obtained with several adenine nucleotide agonists in NG108-15 cells as well as their parent cell line C6Bu-1 and N18TG-2 cells, all of which possess functional adenosine A2 receptors. When NG108-15 cells were incubated with [3H]ATP or [3H]AMP in the presence of ADA, [3H]adenosine was found to distribute dominantly on the cell surface. NG108-15 cells expressed mRNA for the ecto-ATPase and nucleotide pyrophosphatase, but not for CD73. These results suggest that local adenosine formation by an ecto-enzyme distinct from CD73 is involved in adenine nucleotide-induced cyclic AMP formation in NG108-15 cells.
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Affiliation(s)
- S Ohkubo
- Department of Cellular Signaling, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
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