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Dias L, Pochmann D, Lemos C, Silva HB, Real JI, Gonçalves FQ, Rial D, Gonçalves N, Simões AP, Ferreira SG, Agostinho P, Cunha RA, Tomé AR. Increased Synaptic ATP Release and CD73-Mediated Formation of Extracellular Adenosine in the Control of Behavioral and Electrophysiological Modifications Caused by Chronic Stress. ACS Chem Neurosci 2023; 14:1299-1309. [PMID: 36881648 PMCID: PMC10080657 DOI: 10.1021/acschemneuro.2c00810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023] Open
Abstract
Increased ATP release and its extracellular catabolism through CD73 (ecto-5'-nucleotidase) lead to the overactivation of adenosine A2A receptors (A2AR), which occurs in different brain disorders. A2AR blockade blunts mood and memory dysfunction caused by repeated stress, but it is unknown if increased ATP release coupled to CD73-mediated formation of extracellular adenosine is responsible for A2AR overactivation upon repeated stress. This was now investigated in adult rats subject to repeated stress for 14 consecutive days. Frontocortical and hippocampal synaptosomes from stressed rats displayed an increased release of ATP upon depolarization, coupled to an increased density of vesicular nucleotide transporters and of CD73. The continuous intracerebroventricular delivery of the CD73 inhibitor α,β-methylene ADP (AOPCP, 100 μM) during restraint stress attenuated mood and memory dysfunction. Slice electrophysiological recordings showed that restraint stress decreased long-term potentiation both in prefrontocortical layer II/III-layer V synapses and in hippocampal Schaffer fibers-CA1 pyramid synapses, which was prevented by AOPCP, an effect occluded by adenosine deaminase and by the A2AR antagonist SCH58261. These results indicate that increased synaptic ATP release coupled to CD73-mediated formation of extracellular adenosine contributes to mood and memory dysfunction triggered by repeated restraint stress. This prompts considering interventions decreasing ATP release and CD73 activity as novel strategies to mitigate the burden of repeated stress.
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Affiliation(s)
- Liliana Dias
- CNC─Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal.,FMUC─Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Daniela Pochmann
- CNC─Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Cristina Lemos
- CNC─Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Henrique B Silva
- CNC─Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Joana I Real
- CNC─Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Francisco Q Gonçalves
- CNC─Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Daniel Rial
- CNC─Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Nélio Gonçalves
- CNC─Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Ana Patrícia Simões
- CNC─Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Samira G Ferreira
- CNC─Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Paula Agostinho
- CNC─Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal.,FMUC─Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Rodrigo A Cunha
- CNC─Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal.,FMUC─Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Angelo R Tomé
- CNC─Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal.,Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, 3004-517 Coimbra, Portugal
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Pereira ADS, Miron VV, Castro MFV, Bottari NB, Assmann CE, Nauderer JN, Bissacotti BF, Mostardeiro VB, Stefanello N, Baldissarelli J, Palma TV, Morsch VMM, Schetinger MRC. Neuromodulatory effect of the combination of metformin and vitamin D 3 triggered by purinergic signaling in type 1 diabetes induced-rats. Mol Cell Endocrinol 2023; 563:111852. [PMID: 36657632 DOI: 10.1016/j.mce.2023.111852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 01/09/2023] [Accepted: 01/10/2023] [Indexed: 01/18/2023]
Abstract
Several studies have indicated the vitamin D deficiency in the development of macro- and microvascular complications of diabetes mellitus (DM) including DM-related cognitive dysfunction. The purinergic system plays an important role in the modulation of a variety of mechanisms, including neuroinflammation, plasticity, and cell-cell communication. In addition, purines, their receptors, and enzymes can regulate the purinergic axis at different levels in type 1 DM (T1DM). This study evaluated the effects of vitamin D3 alone or in combination with metformin in the behavioral performance of streptozotocin-induced T1DM rats. The effects of this combination on the metabolism of ATP and ADP were also studied by NTPDase (CD39), AMP by 5'-nucleotidase (CD73), and adenosine by adenosine deaminase (E-ADA) in the brain and peripheral lymphocytes of type 1 diabetic STZ-induced rats. The results showed that anxiety and memory loss from the DM condition reverted after 30 days of vitamin D3 treatment. Furthermore, the DM state affected systemic enzymes, with no effect on the central enzymes hydrolyzing extracellular nucleotides and nucleosides. Vitamin D3 treatment positively regulated ectonucleotidase (NTPDase and 5'-nucleotidase) activity, E-ADA, and the purinergic receptors as a mechanism to prevent oxidative damage in the cerebral cortex of T1DM rats. A neuroprotector effect of vitamin D3 through adenosine signaling was also observed, by regulating A1 and A2A receptors proteins levels. The present findings suggest that purinergic signaling through vitamin D3 modulation may be a novel alternative strategy for T1DM treatment, and may compensate for the negative changes in the central nervous system.
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Affiliation(s)
- Aline da Silva Pereira
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil.
| | - Vanessa Valéria Miron
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil
| | - Milagros Fanny Vera Castro
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil
| | - Nathieli Bianchin Bottari
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil
| | - Charles Elias Assmann
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil
| | - Jelson Norberto Nauderer
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil
| | - Bianca Fagan Bissacotti
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil
| | - Vitor Bastianello Mostardeiro
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil
| | - Naiara Stefanello
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil
| | - Jucimara Baldissarelli
- Departamento de Fisiologia e Farmacologia, Universidade Federal de Pelotas (UFPEL), Pelotas, RS, Brazil
| | - Taís Vidal Palma
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil
| | - Vera Maria Melchiors Morsch
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil
| | - Maria Rosa Chitolina Schetinger
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil.
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Gonçalves FQ, Matheus FC, Silva HB, Real JI, Rial D, Rodrigues RJ, Oses JP, Silva AC, Gonçalves N, Prediger RD, Tomé ÂR, Cunha RA. Increased ATP Release and Higher Impact of Adenosine A 2A Receptors on Corticostriatal Plasticity in a Rat Model of Presymptomatic Parkinson's Disease. Mol Neurobiol 2023; 60:1659-1674. [PMID: 36547848 PMCID: PMC9899190 DOI: 10.1007/s12035-022-03162-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 12/06/2022] [Indexed: 12/24/2022]
Abstract
Extracellular ATP can be a danger signal, but its role in striatal circuits afflicted in Parkinson's disease (PD) is unclear and was now investigated. ATP was particularly released at high stimulation intensities from purified striatal nerve terminals of mice, which were endowed with different ATP-P2 receptors (P2R), although P2R antagonists did not alter corticostriatal transmission or plasticity. Instead, ATP was extracellularly catabolized into adenosine through CD73 to activate adenosine A2A receptors (A2AR) modulating corticostriatal long-term potentiation (LTP) in mice. In the presymptomatic phase of a 6-hydroxydopamine rat model of PD, ATP release from striatal nerve terminals was increased and was responsible for a greater impact of CD73 and A2AR on corticostriatal LTP. These observations identify increased ATP release and ATP-derived formation of extracellular adenosine bolstering A2AR activation as a key pathway responsible for abnormal synaptic plasticity in circuits involved in the onset of PD motor symptoms. The translation of these findings to humans prompts extending the use of A2AR antagonists from only co-adjuvants of motor control in Parkinsonian patients to neuroprotective drugs delaying the onset of motor symptoms.
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Affiliation(s)
| | - Filipe C. Matheus
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal ,Department of Pharmacology, Center of Biological Sciences, Federal University of Santa Catarina (UFSC), Florianópolis, SC Brazil
| | - Henrique B. Silva
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Joana I. Real
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Daniel Rial
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Ricardo J. Rodrigues
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Jean-Pierre Oses
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - António C. Silva
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Nélio Gonçalves
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Rui D. Prediger
- Department of Pharmacology, Center of Biological Sciences, Federal University of Santa Catarina (UFSC), Florianópolis, SC Brazil
| | - Ângelo R. Tomé
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal ,Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, Coimbra, Portugal
| | - Rodrigo A. Cunha
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal ,Faculty of Medicine, University of Coimbra, Coimbra, Portugal
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Nucleoside transporters and immunosuppressive adenosine signaling in the tumor microenvironment: Potential therapeutic opportunities. Pharmacol Ther 2022; 240:108300. [PMID: 36283452 DOI: 10.1016/j.pharmthera.2022.108300] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 10/17/2022] [Accepted: 10/19/2022] [Indexed: 11/30/2022]
Abstract
Adenosine compartmentalization has a profound impact on immune cell function by regulating adenosine localization and, therefore, extracellular signaling capabilities, which suppresses immune cell function in the tumor microenvironment. Nucleoside transporters, responsible for the translocation and cellular compartmentalization of hydrophilic adenosine, represent an understudied yet crucial component of adenosine disposition in the tumor microenvironment. In this review article, we will summarize what is known regarding nucleoside transporter's function within the purinome in relation to currently devised points of intervention (i.e., ectonucleotidases, adenosine receptors) for cancer immunotherapy, alterations in nucleoside transporter expression reported in cancer, and potential avenues for targeting of nucleoside transporters for the desired modulation of adenosine compartmentalization and action. Further, we put forward that nucleoside transporters are an unexplored therapeutic opportunity, and modulation of nucleoside transport processes could attenuate the pathogenic buildup of immunosuppressive adenosine in solid tumors, particularly those enriched with nucleoside transport proteins.
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Simões AP, Gonçalves FQ, Rial D, Ferreira SG, Lopes JP, Canas PM, Cunha RA. CD73-Mediated Formation of Extracellular Adenosine Is Responsible for Adenosine A 2A Receptor-Mediated Control of Fear Memory and Amygdala Plasticity. Int J Mol Sci 2022; 23:12826. [PMID: 36361618 PMCID: PMC9653840 DOI: 10.3390/ijms232112826] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 10/14/2022] [Accepted: 10/19/2022] [Indexed: 08/27/2023] Open
Abstract
Adenosine A2A receptors (A2AR) control fear memory and the underlying processes of synaptic plasticity in the amygdala. In other brain regions, A2AR activation is ensured by ATP-derived extracellular adenosine formed by ecto-5'-nucleotidase or CD73. We now tested whether CD73 is also responsible to provide for the activation of A2AR in controlling fear memory and amygdala long-term potentiation (LTP). The bilateral intracerebroventricular injection of the CD73 inhibitor αβ-methylene ADP (AOPCP, 1 nmol/ventricle/day) phenocopied the effect of the A2AR blockade by decreasing the expression of fear memory, an effect disappearing in CD73-knockout (KO) mice and in forebrain neuronal A2AR-KO mice. In the presence of PPADS (20 μM) to eliminate any modification of ATP/ADP-mediated P2 receptor effects, both AOPCP (100 μM) and the A2AR antagonist, SCH58261 (50 nM), decreased LTP magnitude in synapses of projection from the external capsula into the lateral amygdala, an effect eliminated in slices from both forebrain neuronal A2AR-KO mice and CD73-KO mice. These data indicate a key role of CD73 in the process of A2AR-mediated control of fear memory and underlying synaptic plasticity processes in the amygdala, paving the way to envisage CD73 as a new therapeutic target to interfere with abnormal fear-like emotional processing.
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Affiliation(s)
- Ana Patrícia Simões
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Francisco Q. Gonçalves
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Daniel Rial
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Samira G. Ferreira
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - João Pedro Lopes
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Paula M. Canas
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Rodrigo A. Cunha
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
- Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal
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Valada P, Hinz S, Vielmuth C, Lopes CR, Cunha RA, Müller CE, Lopes JP. The impact of inosine on hippocampal synaptic transmission and plasticity involves the release of adenosine through equilibrative nucleoside transporters rather than the direct activation of adenosine receptors. Purinergic Signal 2022:10.1007/s11302-022-09899-7. [PMID: 36156760 DOI: 10.1007/s11302-022-09899-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 09/13/2022] [Indexed: 11/24/2022] Open
Abstract
Inosine has robust neuroprotective effects, but it is unclear if inosine acts as direct ligand of adenosine receptors or if it triggers metabolic effects indirectly modifying the activity of adenosine receptors. We now combined radioligand binding studies with electrophysiological recordings in hippocampal slices to test how inosine controls synaptic transmission and plasticity. Inosine was without effect at 30 μM and decreased field excitatory post-synaptic potentials by 14% and 33% at 100 and 300 μM, respectively. These effects were prevented by the adenosine A1 receptor antagonist DPCPX. Inosine at 300 (but not 100) μM also decreased the magnitude of long-term potentiation (LTP), an effect prevented by DPCPX and by the adenosine A2A receptor antagonist SCH58261. Inosine showed low affinity towards human and rat adenosine receptor subtypes with Ki values of > 300 µM; only at the human and rat A1 receptor slightly higher affinities with Ki values of around 100 µM were observed. Affinity of inosine at the rat A3 receptor was higher (Ki of 1.37 µM), while it showed no interaction with the human orthologue. Notably, the effects of inosine on synaptic transmission and plasticity were abrogated by adenosine deaminase and by inhibiting equilibrative nucleoside transporters (ENT) with dipyridamole and NBTI. This shows that the impact of inosine on hippocampal synaptic transmission and plasticity is not due to a direct activation of adenosine receptors but is instead due to an indirect modification of the tonic activation of these adenosine receptors through an ENT-mediated modification of the extracellular levels of adenosine.
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Affiliation(s)
- Pedro Valada
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504, Coimbra, Portugal
| | - Sonja Hinz
- Pharmaceutical & Medicinal Chemistry, University of Bonn, 53121, Bonn, Germany
| | - Christin Vielmuth
- Pharmaceutical & Medicinal Chemistry, University of Bonn, 53121, Bonn, Germany
| | - Cátia R Lopes
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504, Coimbra, Portugal
| | - Rodrigo A Cunha
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504, Coimbra, Portugal. .,Faculty of Medicine, University of Coimbra, Coimbra, Portugal.
| | - Christa E Müller
- Pharmaceutical & Medicinal Chemistry, University of Bonn, 53121, Bonn, Germany
| | - João Pedro Lopes
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504, Coimbra, Portugal
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Huang Y, Wei Y, Xu J, Wei X. A comprehensive review on the prevention and regulation of Alzheimer's disease by tea and its active ingredients. Crit Rev Food Sci Nutr 2022; 63:10560-10584. [PMID: 35647742 DOI: 10.1080/10408398.2022.2081128] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Alzheimer's disease (AD) has brought a heavy burden to society as a representative neurodegenerative disease. The etiology of AD combines multiple factors, concluding family, gender, head trauma, diseases and social psychology. There are multiple hypotheses explaining the pathogenesis of AD such as β-amyloid (Aβ) deposition and tau hyperphosphorylation, which lead to extracellular amyloid plaques and neurofibrillary tangles in neurons. The existing therapeutic drugs have several disadvantages including single target, poor curative effect, and obvious side effects. Tea contains many bioactive components, such as tea polyphenols (TPP), L-theanine (L-TH), tea pigment, tea polysaccharides and caffeine. The epidemiological investigations have shown that drinking tea can reduce the risk of AD. The mechanisms of tea active ingredients in the prevention and regulation of AD includes reducing the generation and aggregation of Aβ; inhibiting tau aggregation and hyperphosphorylation; inhibiting neuronal apoptosis and regulate neurotransmitters; relieving oxidative stress and neuroinflammation as well as the regulation of intestinal flora. This review summarizes the different signaling pathways that tea active ingredients regulate AD. Furthermore, we propose the main limitations of current research and future research directions, hoping to contribute to the development of natural functional foods based on tea active ingredients in the prevention and treatment of AD.
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Affiliation(s)
- Yi Huang
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, PR China
| | - Yang Wei
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, PR China
| | - Jia Xu
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, PR China
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai, PR China
| | - Xinlin Wei
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, PR China
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Blockade of adenosine A 2A receptor alleviates cognitive dysfunction after chronic exposure to intermittent hypoxia in mice. Exp Neurol 2021; 350:113929. [PMID: 34813840 DOI: 10.1016/j.expneurol.2021.113929] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 10/25/2021] [Accepted: 11/16/2021] [Indexed: 11/22/2022]
Abstract
Obstructive sleep apnea-hypopnea syndrome (OSAHS) is widely known for its multiple systems damage, especially neurocognitive deficits in children. Since their discovery, adenosine A2A receptors (A2ARs) have been considered as key elements in signaling pathways mediating neurodegenerative diseases such as Huntington's and Alzheimer's, as well as cognitive function regulation. Herein, we investigated A2AR role in cognitive impairment induced by chronic intermittent hypoxia (CIH). Mice were exposed to CIH 7 h every day for 4 weeks, and intraperitoneally injected with A2AR agonist CGS21680 or A2AR antagonist SCH58261 half an hour before IH exposure daily. The 8-arm radial arm maze was utilized to assess spatial memory after CIH exposures.To validate findings using pharmacology, the impact of intermittent hypoxia was investigated in A2AR knockout mice. CIH-induced memory dysfunction was manifested by increased error rates in the radial arm maze test. The behavioral changes were associated with hippocampal pathology, neuronal apoptosis, and synaptic plasticity impairment. The stimulation of adenosine A2AR exacerbated memory impairment with more serious neuropathological damage, attenuated long-term potentiation (LTP), syntaxin down-regulation, and increased BDNF protein. Moreover, apoptosis-promoting protein cleaved caspase-3 was upregulated while anti-apoptotic protein Bcl-2 was downregulated. Consistent with these findings, A2AR inhibition with SCH58261 and A2AR deletion exhibited the opposite result. Overall, these findings suggest that A2AR plays a critical role in CIH-induced impairment of learning and memory by accelerating hippocampal neuronal apoptosis and reducing synaptic plasticity. Blockade of adenosine A2A receptor alleviates cognitive dysfunction after chronic exposure to intermittent hypoxia in mice.
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Oxidative Stress Caused by Ozone Exposure Induces Changes in P2X7 Receptors, Neuroinflammation, and Neurodegeneration in the Rat Hippocampus. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:3790477. [PMID: 34790285 PMCID: PMC8592727 DOI: 10.1155/2021/3790477] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 10/19/2021] [Indexed: 02/05/2023]
Abstract
Low-ozone doses cause alterations in the oxidation-reduction mechanisms due to the increase in reactive oxygen species, alter cell signaling, and produce deleterious metabolic responses for cells. Adenosine 5'triphosphate (ATP) can act as a mediator in intercellular communication between neurons and glial cells. When there is an increase in extracellular ATP, a modification is promoted in the regulation of inflammation, energy metabolism, by affecting the intracellular signaling pathways that participate in these processes. The objective of this work was to study changes in the P2X7 receptor, and their relationship with the inflammatory response and energy metabolism, in a model of progressive neurodegeneration in the hippocampus of rats chronically exposed to low-ozone doses. Therefore, 72 male rats were exposed to low-ozone doses for different periods of time. After exposure to ozone was finished, rats were processed for immunohistochemical techniques, western blot, quantitative polymerase chain reaction (qPCR), and histological techniques for periodic acid-Schiff staining. The results showed immunoreactivity changes in the amount of the P2X7 protein. There was an increase in phosphorylation for glycogen synthase kinase 3-β (GSK3-β) as treatment continued. There were also increases in 27 interleukin 1 beta (IL-1 β) and interleukin 17 (IL-17) and a decrease in interleukin 10 (IL-10). Furthermore, neuronal glycogen was found at 30 and 60 days, and an increase in caspase 3. An increase in mRNA was also shown for the P2X7 gene at 60 days, and GSK3-β at 90 days of exposure. In conclusion, these results suggest that repeated exposure to low-ozone doses, such as those that can occur during highly polluted days, causes a state of oxidative stress, leading to alterations in the P2X7 receptors, which promote changes in the activation of signaling pathways for inflammatory processes and cell death, converging at a progressive neurodegeneration process, as may be happening in Alzheimer's disease.
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Zhou X, Zhang L. The Neuroprotective Effects of Moderate and Regular Caffeine Consumption in Alzheimer's Disease. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:5568011. [PMID: 34447487 PMCID: PMC8384510 DOI: 10.1155/2021/5568011] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 06/27/2021] [Accepted: 07/19/2021] [Indexed: 12/25/2022]
Abstract
The increasing numbers of elderly Alzheimer's disease (AD) patients because of a steady increase in the average lifespan and aging society attract great scientific concerns, while there were fewer effective treatments on AD progression due to unclear exact causes and pathogenesis of AD. Moderate (200-500 mg/d) and regular caffeine consumption from coffee and tea are considered to alleviate the risk of AD and have therapeutic potential. This paper reviewed epidemiological studies about the relationship of caffeine intake from coffee or/and tea with the risk of AD and summarized the caffeine-related AD therapies based on experimental models. And further well-designed and well-conducted studies are suggested to investigate the optimal dosages, frequencies, and durations of caffeine consumption to slow down AD progression and treat AD.
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Affiliation(s)
- Xiangyu Zhou
- School of Food Science and Nutrition, University of Leeds, Leeds, West Yorkshire LS2 9JT, UK
| | - Lin Zhang
- The Key Laboratory for Special Medical Food Process in Hunan Province, Central South University of Forestry and Technology, Changsha, Hunan 410004, China
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11
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Purinergic signaling orchestrating neuron-glia communication. Pharmacol Res 2020; 162:105253. [PMID: 33080321 DOI: 10.1016/j.phrs.2020.105253] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 09/29/2020] [Accepted: 10/09/2020] [Indexed: 12/12/2022]
Abstract
This review discusses the evidence supporting a role for ATP signaling (operated by P2X and P2Y receptors) and adenosine signaling (mainly operated by A1 and A2A receptors) in the crosstalk between neurons, astrocytes, microglia and oligodendrocytes. An initial emphasis will be given to the cooperation between adenosine receptors to sharpen information salience encoding across synapses. The interplay between ATP and adenosine signaling in the communication between astrocytes and neurons will then be presented in context of the integrative properties of the astrocytic syncytium, allowing to implement heterosynaptic depression processes in neuronal networks. The process of microglia 'activation' and its control by astrocytes and neurons will then be analyzed under the perspective of an interplay between different P2 receptors and adenosine A2A receptors. In spite of these indications of a prominent role of purinergic signaling in the bidirectional communication between neurons and glia, its therapeutical exploitation still awaits obtaining an integrated view of the spatio-temporal action of ATP signaling and adenosine signaling, clearly distinguishing the involvement of both purinergic signaling systems in the regulation of physiological processes and in the control of pathogenic-like responses upon brain dysfunction or damage.
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12
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Ramos AC, de Mattos Hungria F, Camerini BA, Suiama MA, Calzavara MB. Potential beneficial effects of caffeine administration in the neonatal period of an animal model of schizophrenia. Behav Brain Res 2020; 391:112674. [PMID: 32417274 DOI: 10.1016/j.bbr.2020.112674] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 04/03/2020] [Accepted: 04/24/2020] [Indexed: 12/17/2022]
Abstract
Obstetric complications, like maternal hypertension and neonatal hypoxia, disrupt brain development, leading to psychiatry disorders later in life, like schizophrenia. The exact mechanisms behind this risk are not yet well known. Spontaneously hypertensive rats (SHR) are a well-established model to study neurodevelopment of schizophrenia since they exhibit behavioral alterations mimicking schizophrenia that can be improved with antipsychotic drugs. SHR mothers are hypertensive, and the SHR offspring develop in preeclampsia-like conditions. Hypoxic conditions increase levels of adenosine, which play an important role in brain development. The enhanced levels of adenosine at birth could be related to the future development of schizophrenia. To investigate this hypothesis adenosine levels of brain neonatal Wistar rats and SHR were quantified. After that, caffeine, an antagonist of adenosinergic system, was administrated on PND (postnatal day) 7 (neurodevelopmental age similar to a human at delivery) and rats were observed at adolescent and adult ages. We also investigated the acute effects of caffeine at adolescent and adult ages. SHR control adolescent and adult groups presented behavioral deficits like hyperlocomotion, deficit in social interaction (SI), and contextual fear conditioning (CFC). In SHR, neonatal caffeine treatment on PND 7 normalized hyperlocomotion, improved SI, and CFC observed at adolescent period and adult ages, showing a beneficial effect on schizophrenia-like behaviors. Wistar rats neonatally treated with caffeine exhibited hyperlocomotion, deficit in SI and CFC when observed at adolescent and adult ages. Acutely caffeine treatment administrated at adolescent and adult ages increased locomotion and decreased SI time of Wistar rats and impair CFC in adult Wistars. No effects were observed in SHR. In conclusion, caffeine can be suggested as a useful drug to prevent behavioral deficits observed in this animal model of prenatal hypoxia-induced schizophrenia profile when specifically administered on PND 7.
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Affiliation(s)
- Aline Camargo Ramos
- Department of Psychiatry, Universidade Federal De São Paulo, São Paulo, SP, Brazil
| | | | | | - Mayra Akimi Suiama
- Department of Pharmacology, Universidade Federal De São Paulo, São Paulo, SP, Brazil
| | - Mariana Bendlin Calzavara
- Department of Psychiatry, Universidade Federal De São Paulo, São Paulo, SP, Brazil; School of Medicine from Faculdade Israelita De Ciências Da Saúde Albert Einstein, São Paulo, SP, Brazil.
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13
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Pastor-Anglada M, Pérez-Torras S. Who Is Who in Adenosine Transport. Front Pharmacol 2018; 9:627. [PMID: 29962948 PMCID: PMC6010718 DOI: 10.3389/fphar.2018.00627] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 05/24/2018] [Indexed: 12/13/2022] Open
Abstract
Extracellular adenosine concentrations are regulated by a panel of membrane transporters which, in most cases, mediate its uptake into cells. Adenosine transporters belong to two gene families encoding Equilibrative and Concentrative Nucleoside Transporter proteins (ENTs and CNTs, respectively). The lack of appropriate pharmacological tools targeting every transporter subtype has introduced some bias on the current knowledge of the role of these transporters in modulating adenosine levels. In this regard, ENT1, for which pharmacology is relatively well-developed, has often been identified as a major player in purinergic signaling. Nevertheless, other transporters such as CNT2 and CNT3 can also contribute to purinergic modulation based on their high affinity for adenosine and concentrative capacity. Moreover, both transporter proteins have also been shown to be under purinergic regulation via P1 receptors in different cell types, which further supports its relevance in purinergic signaling. Thus, several transporter proteins regulate extracellular adenosine levels. Moreover, CNT and ENT proteins are differentially expressed in tissues but also in particular cell types. Accordingly, transporter-mediated fine tuning of adenosine levels is cell and tissue specific. Future developments focusing on CNT pharmacology are needed to unveil transporter subtype-specific events.
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Affiliation(s)
- Marçal Pastor-Anglada
- Molecular Pharmacology and Experimental Therapeutics, Department of Biochemistry and Molecular Biomedicine, Institute of Biomedicine, University of Barcelona, Barcelona, Spain
- Oncology Program, National Biomedical Research Institute on Liver and Gastrointestinal Diseases – CIBER ehd, Institut de Recerca Sant Joan de Déu, Barcelona, Spain
| | - Sandra Pérez-Torras
- Molecular Pharmacology and Experimental Therapeutics, Department of Biochemistry and Molecular Biomedicine, Institute of Biomedicine, University of Barcelona, Barcelona, Spain
- Oncology Program, National Biomedical Research Institute on Liver and Gastrointestinal Diseases – CIBER ehd, Institut de Recerca Sant Joan de Déu, Barcelona, Spain
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14
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Hartley GL, Watson CL, Ainslie PN, Tokuno CD, Greenway MJ, Gabriel DA, O'Leary DD, Cheung SS. Corticospinal excitability is associated with hypocapnia but not changes in cerebral blood flow. J Physiol 2016; 594:3423-37. [PMID: 26836470 DOI: 10.1113/jp271914] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 01/22/2016] [Indexed: 01/30/2023] Open
Abstract
KEY POINTS Reductions in cerebral blood flow (CBF) may be implicated in the development of neuromuscular fatigue; however, the contribution from hypocapnic-induced reductions (i.e. P ETC O2) in CBF versus reductions in CBF per se has yet to be isolated. We assessed neuromuscular function while using indomethacin to selectively reduce CBF without changes in P ETC O2 and controlled hyperventilation-induced hypocapnia to reduce both CBF and P ETC O2. Increased corticospinal excitability appears to be exclusive to reductions in P ETC O2 but not reductions in CBF, whereas sub-optimal voluntary output from the motor cortex is moderately associated with decreased CBF independent of changes in P ETC O2. These findings suggest that changes in CBF and P ETC O2 have distinct roles in modulating neuromuscular function. ABSTRACT Although reductions in cerebral blood flow (CBF) may be involved in central fatigue, the contribution from hypocapnia-induced reductions in CBF versus reductions in CBF per se has not been isolated. This study examined whether reduced arterial PCO2 (P aC O2), independent of concomitant reductions in CBF, impairs neuromuscular function. Neuromuscular function, as indicated by motor-evoked potentials (MEPs), maximal M-wave (Mmax ) and cortical voluntary activation (cVA) of the flexor carpi radialis muscle during isometric wrist flexion, was assessed in ten males (29 ± 10 years) during three separate conditions: (1) cyclooxygenase inhibition using indomethacin (Indomethacin, 1.2 mg kg(-1) ) to selectively reduce CBF by 28.8 ± 10.3% (estimated using transcranial Doppler ultrasound) without changes in end-tidal PCO2 (P ETC O2); (2) controlled iso-oxic hyperventilation-induced reductions in P aC O2 (Hypocapnia), P ETC O2 = 30.1 ± 4.5 mmHg with related reductions in CBF (21.7 ± 6.3%); and (3) isocapnic hyperventilation (Isocapnia) to examine the potential direct influence of hyperventilation-mediated activation of respiratory control centres on CBF and changes in neuromuscular function. Change in MEP amplitude (%Mmax ) from baseline was greater in Hypocapnia tha in Isocapnia (11.7 ± 9.8%, 95% confidence interval (CI) [2.6, 20.7], P = 0.01) and Indomethacin (13.3 ± 11.3%, 95% CI [2.8, 23.7], P = 0.01) with a large Cohen's effect size (d ≥ 1.17). Although not statistically significant, cVA was reduced with a moderate effect size in Indomethacin (d = 0.7) and Hypocapnia (d = 0.9) compared to Isocapnia. In summary, increased corticospinal excitability - as reflected by larger MEP amplitude - appears to be exclusive to reduced P aC O2, but not reductions in CBF per se. Sub-optimal voluntary output from the motor cortex is moderately associated with decreased CBF, independent of reduced P aC O2.
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Affiliation(s)
- Geoffrey L Hartley
- Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada.,Centre for Physical and Health Education, Schulich School of Education, Nipissing University, North Bay, Ontario, Canada
| | - Cody L Watson
- Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, British Columbia, Canada
| | - Craig D Tokuno
- Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | - Matthew J Greenway
- Michael G. DeGroote School of Medicine, Niagara Regional Campus, McMaster University, Hamilton, Ontario, Canada
| | - David A Gabriel
- Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | - Deborah D O'Leary
- Department of Health Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Stephen S Cheung
- Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
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15
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Düster R, Prickaerts J, Blokland A. Purinergic signaling and hippocampal long-term potentiation. Curr Neuropharmacol 2014; 12:37-43. [PMID: 24533014 PMCID: PMC3915348 DOI: 10.2174/1570159x113119990045] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Revised: 07/01/2013] [Accepted: 08/02/2013] [Indexed: 11/25/2022] Open
Abstract
The purines ATP and adenosine are widely recognized for their neuromodulatory effects. They have been
shown to have effects on neurons via various receptors and interactions with glial cells. In particular, long-term
potentiation (LTP) in hippocampal slice preparations has been found to be modulated by ATP and adenosine. This review
gives an overview of purinergic signaling in relation to hippocampal LTP and memory formation. The data supports the
hypothesis that adenosine mediates a tonic suppression of synaptic transmission. Thus, low adenosine levels appear to
increase basal synaptic activity via a decreased activation of the inhibitor A1 receptor, consequently making it more
difficult to induce LTP because of lower contrast. During high stimulation, the inhibition of neighboring pathways by
adenosine, in combination with an A2a receptor activation, appears to increase contrast of excited pathways against a nonexcited
background. This would enable amplification of specific signaling while suppressing non-specific events.
Although a clear role for purinergic signaling in LTP is evident, more studies are needed to scrutinize the modulatory role
of ATP and adenosine and their receptors in synaptic plasticity and memory.
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Affiliation(s)
- Robert Düster
- Institute II for Anatomy, Medical Faculty, University of Cologne, Cologne, Germany
| | - Jos Prickaerts
- Department of Psychiatry and Neuropsychology, Faculty of Health, Medicine and Life Sciences, European School of Neuroscience (EURON), Maastricht University, Maastricht, The Netherlands
| | - Arjan Blokland
- Department of Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, European School of Neuroscience (EURON), Maastricht University, Maastricht, The Netherlands
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16
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Marisco PC, Carvalho FB, Rosa MM, Girardi BA, Gutierres JM, Jaques JAS, Salla APS, Pimentel VC, Schetinger MRC, Leal DBR, Mello CF, Rubin MA. Piracetam prevents scopolamine-induced memory impairment and decrease of NTPDase, 5'-nucleotidase and adenosine deaminase activities. Neurochem Res 2013; 38:1704-14. [PMID: 23677777 DOI: 10.1007/s11064-013-1072-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Revised: 04/29/2013] [Accepted: 05/07/2013] [Indexed: 11/26/2022]
Abstract
Piracetam improves cognitive function in animals and in human beings, but its mechanism of action is still not completely known. In the present study, we investigated whether enzymes involved in extracellular adenine nucleotide metabolism, adenosine triphosphate diphosphohydrolase (NTPDase), 5'-nucleotidase and adenosine deaminase (ADA) are affected by piracetam in the hippocampus and cerebral cortex of animals subjected to scopolamine-induced memory impairment. Piracetam (0.02 μmol/5 μL, intracerebroventricular, 60 min pre-training) prevented memory impairment induced by scopolamine (1 mg/kg, intraperitoneal, immediately post-training) in the inhibitory avoidance learning and in the object recognition task. Scopolamine reduced the activity of NTPDase in hippocampus (53 % for ATP and 53 % for ADP hydrolysis) and cerebral cortex (28 % for ATP hydrolysis). Scopolamine also decreased the activity of 5'-nucleotidase (43 %) and ADA (91 %) in hippocampus. The same effect was observed in the cerebral cortex for 5'-nucleotidase (38 %) and ADA (68 %) activities. Piracetam fully prevented scopolamine-induced memory impairment and decrease of NTPDase, 5'-nucleotidase and adenosine deaminase activities in synaptosomes from cerebral cortex and hippocampus. In vitro experiments show that piracetam and scopolamine did not alter enzymatic activity in cerebral cortex synaptosomes. Moreover, piracetam prevented scopolamine-induced increase of TBARS levels in hippocampus and cerebral cortex. These results suggest that piracetam-induced improvement of memory is associated with protection against oxidative stress and maintenance of NTPDase, 5'-nucleotidase and ADA activities, and suggest the purinergic system as a putative target of piracetam.
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Affiliation(s)
- Patricia C Marisco
- Graduation Program in Pharmacology, Center of Health Sciences (CCS), Federal University of Santa Maria, Santa Maria, RS, CEP 97105-900, Brazil
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17
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Abstract
Memory consolidation in a discriminative bead pecking task is modulated by endogenous adenosine triphosphate (ATP) acting at purinergic receptors in the hippocampus. Consolidation, from short- to intermediate- to long-term memory during two distinct periods following training, was blocked by the non-selective P2 purinergic receptor antagonist PPADS (pyridoxal phosphate-6-azo(benzene-2,4-disulphonic acid) tetrasodium salt hydrate and the specific P2Y1 receptor antagonist MRS2179. Direct injections of the ATP agonists (ATPγS and ADPβS) potentiated memory consolidation and the effect of ADPβS was blocked by MRS2179, suggesting an important role of ATP on memory consolidation via the P2Y1 receptor in the chick hippocampus. Incubation of astrocytes with ATPγS and ADPβS resulted in the increase of intracellular calcium ([Ca2+]i), the latter being blocked by MRS2179 suggesting a specific role for P2Y1 receptors in the calcium response. This response was prevented by blocking astrocytic oxidative metabolism with fluoroacetate. We argue that the source of the ATP acting on neuronal P2Y1 receptors is most likely to be astrocytes. Thrombin selectively increases [Ca2+]i in astrocytes but not in neurones. The main findings of the present study are: (a) astrocytic [Ca2+]i plays an important role in the consolidation of short-term to long-term memory; and (b) ATP released from chick astrocytes during learning modulates neuronal activity through astrocytic P2Y1 receptors.
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18
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Burnstock G, Krügel U, Abbracchio MP, Illes P. Purinergic signalling: from normal behaviour to pathological brain function. Prog Neurobiol 2011; 95:229-74. [PMID: 21907261 DOI: 10.1016/j.pneurobio.2011.08.006] [Citation(s) in RCA: 314] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 08/12/2011] [Accepted: 08/15/2011] [Indexed: 02/07/2023]
Abstract
Purinergic neurotransmission, involving release of ATP as an efferent neurotransmitter was first proposed in 1972. Later, ATP was recognised as a cotransmitter in peripheral nerves and more recently as a cotransmitter with glutamate, noradrenaline, GABA, acetylcholine and dopamine in the CNS. Both ATP, together with some of its enzymatic breakdown products (ADP and adenosine) and uracil nucleotides are now recognised to act via P2X ion channels and P1 and P2Y G protein-coupled receptors, which are widely expressed in the brain. They mediate both fast signalling in neurotransmission and neuromodulation and long-term (trophic) signalling in cell proliferation, differentiation and death. Purinergic signalling is prominent in neurone-glial cell interactions. In this review we discuss first the evidence implicating purinergic signalling in normal behaviour, including learning and memory, sleep and arousal, locomotor activity and exploration, feeding behaviour and mood and motivation. Then we turn to the involvement of P1 and P2 receptors in pathological brain function; firstly in trauma, ischemia and stroke, then in neurodegenerative diseases, including Alzheimer's, Parkinson's and Huntington's, as well as multiple sclerosis and amyotrophic lateral sclerosis. Finally, the role of purinergic signalling in neuropsychiatric diseases (including schizophrenia), epilepsy, migraine, cognitive impairment and neuropathic pain will be considered.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London NW3 2PF, UK.
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19
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Intracellular ATP influences synaptic plasticity in area CA1 of rat hippocampus via metabolism to adenosine and activity-dependent activation of adenosine A1 receptors. J Neurosci 2011; 31:6221-34. [PMID: 21508245 DOI: 10.1523/jneurosci.4039-10.2011] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The extent to which brain slices reflect the energetic status of the in vivo brain has been a subject of debate. We addressed this issue to investigate the recovery of energetic parameters and adenine nucleotides in rat hippocampal slices and the influence this has on synaptic transmission and plasticity. We show that, although adenine nucleotide levels recover appreciably within 10 min of incubation, it takes 3 h for a full recovery of the energy charge (to ≥ 0.93) and that incubation of brain slices at 34°C results in a significantly higher ATP/AMP ratio and a threefold lower activity of AMP-activated protein kinase compared with slices incubated at room temperature. Supplementation of artificial CSF with d-ribose and adenine (Rib/Ade) increased the total adenine nucleotide pool of brain slices, which, when corrected for the influence of the dead cut edges, closely approached in vivo values. Rib/Ade did not affect basal synaptic transmission or paired-pulse facilitation but did inhibit long-term potentiation (LTP) induced by tetanic or weak theta-burst stimulation. This decrease in LTP was reversed by strong theta-burst stimulation or antagonizing the inhibitory adenosine A(1) receptor suggesting that the elevated tissue ATP levels had resulted in greater activity-dependent adenosine release during LTP induction. This was confirmed by direct measurement of adenosine release with adenosine biosensors. These observations provide new insight into the recovery of adenine nucleotides after slice preparation, the sources of loss of such compounds in brain slices, the means by which to restore them, and the functional consequences of doing so.
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20
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Lorca RA, Rozas C, Loyola S, Moreira-Ramos S, Zeise ML, Kirkwood A, Huidobro-Toro JP, Morales B. Zinc enhances long-term potentiation through P2X receptor modulation in the hippocampal CA1 region. Eur J Neurosci 2011; 33:1175-1185. [PMID: 21324005 DOI: 10.1111/j.1460-9568.2010.07589.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Zn²(+) is an essential ion that is stored in and co-released from glutamatergic synapses and it modulates neurotransmitter receptors involved in long-term potentiation (LTP). However, the mechanism(s) underlying Zn²(+) -induced modulation of LTP remain(s) unclear. As the purinergic P2X receptors are relevant targets for Zn²(+) action, we have studied their role in LTP modulation by Zn²(+) in the CA1 region of rat hippocampal slices. Induction of LTP in the presence of Zn²(+) revealed a biphasic effect - 5-50 μm enhanced LTP induction, whereas 100-300 μm Zn²(+) inhibited LTP. The involvement of a purinergic mechanism is supported by the fact that application of the P2X receptor antagonists 2',3'-O-(2,4,6-trinitrophenyl) ATP (TNP-ATP) and periodate-oxidized ATP fully abolished the facilitatory effect of Zn²(+) . Notably, application of the P2X₇ receptor-specific antagonist Brilliant Blue G did not modify the Zn²(+) -dependent facilitation of LTP. Exogenous ATP also produced a biphasic effect - 0.1-1 μm ATP facilitated LTP, whereas 5-10 μm inhibited LTP. The facilitatory effect of ATP was abolished by the application of TNP-ATP and was modified in the presence of 5 μm Zn²(+) , suggesting that P2X receptors are involved in LTP induction and that Zn²(+) leads to an increase in the affinity of P2X receptors for ATP. The latter confirms our previous results from heterologous expression systems. Collectively, our results indicate that Zn²(+) at low concentrations enhances LTP by modulating P2X receptors. Although it is not yet clear which purinergic receptor subtype(s) is responsible for these effects on LTP, the data presented here suggest that P2X₄ but not P2X₇ is involved.
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Affiliation(s)
- Ramón A Lorca
- Laboratorio de Neurociencias, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago 9170022, Chile.,Laboratorio de Nucleótidos, Centro de Regulación Celular y Patología, J.V. Luco, Instituto MIFAB, Departamento de Fisiología, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Santiago, Chile
| | - Carlos Rozas
- Laboratorio de Neurociencias, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago 9170022, Chile
| | - Sebastian Loyola
- Laboratorio de Neurociencias, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago 9170022, Chile
| | - Sandra Moreira-Ramos
- Laboratorio de Neurociencias, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago 9170022, Chile
| | - Marc L Zeise
- Escuela de Psicología, Universidad de Santiago de Chile, Santiago, Chile
| | - Alfredo Kirkwood
- Mind/Brain Institute and Department of Neurosciences, Johns Hopkins University, Baltimore, MD, USA
| | - J Pablo Huidobro-Toro
- Laboratorio de Nucleótidos, Centro de Regulación Celular y Patología, J.V. Luco, Instituto MIFAB, Departamento de Fisiología, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Santiago, Chile
| | - Bernardo Morales
- Laboratorio de Neurociencias, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago 9170022, Chile
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21
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Lusardi TA. Adenosine neuromodulation and traumatic brain injury. Curr Neuropharmacol 2010; 7:228-37. [PMID: 20190964 PMCID: PMC2769006 DOI: 10.2174/157015909789152137] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Revised: 05/18/2009] [Accepted: 05/20/2009] [Indexed: 12/17/2022] Open
Abstract
Adenosine is a ubiquitous signaling molecule, with widespread activity across all organ systems. There is evidence that adenosine regulation is a significant factor in traumatic brain injury (TBI) onset, recovery, and outcome, and a growing body of experimental work examining the therapeutic potential of adenosine neuromodulation in the treatment of TBI. In the central nervous system (CNS), adenosine (dys)regulation has been demonstrated following TBI, and correlated to several TBI pathologies, including impaired cerebral hemodynamics, anaerobic metabolism, and inflammation. In addition to acute pathologies, adenosine function has been implicated in TBI comorbidities, such as cognitive deficits, psychiatric function, and post-traumatic epilepsy. This review presents studies in TBI as well as adenosine-related mechanisms in co-morbidities of and unfavorable outcomes resulting from TBI. While the exact role of the adenosine system following TBI remains unclear, there is increasing evidence that a thorough understanding of adenosine signaling will be critical to the development of diagnostic and therapeutic tools for the treatment of TBI.
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Affiliation(s)
- T A Lusardi
- R. S. Dow Neurobiology Laboratory, Portland OR, USA.
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22
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Abstract
The adenosine receptors (ARs) in the nervous system act as a kind of "go-between" to regulate the release of neurotransmitters (this includes all known neurotransmitters) and the action of neuromodulators (e.g., neuropeptides, neurotrophic factors). Receptor-receptor interactions and AR-transporter interplay occur as part of the adenosine's attempt to control synaptic transmission. A(2A)ARs are more abundant in the striatum and A(1)ARs in the hippocampus, but both receptors interfere with the efficiency and plasticity-regulated synaptic transmission in most brain areas. The omnipresence of adenosine and A(2A) and A(1) ARs in all nervous system cells (neurons and glia), together with the intensive release of adenosine following insults, makes adenosine a kind of "maestro" of the tripartite synapse in the homeostatic coordination of the brain function. Under physiological conditions, both A(2A) and A(1) ARs play an important role in sleep and arousal, cognition, memory and learning, whereas under pathological conditions (e.g., Parkinson's disease, Alzheimer's disease, amyotrophic lateral sclerosis, stroke, epilepsy, drug addiction, pain, schizophrenia, depression), ARs operate a time/circumstance window where in some circumstances A(1)AR agonists may predominate as early neuroprotectors, and in other circumstances A(2A)AR antagonists may alter the outcomes of some of the pathological deficiencies. In some circumstances, and depending on the therapeutic window, the use of A(2A)AR agonists may be initially beneficial; however, at later time points, the use of A(2A)AR antagonists proved beneficial in several pathologies. Since selective ligands for A(1) and A(2A) ARs are now entering clinical trials, the time has come to determine the role of these receptors in neurological and psychiatric diseases and identify therapies that will alter the outcomes of these diseases, therefore providing a hopeful future for the patients who suffer from these diseases.
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Affiliation(s)
- Ana M Sebastião
- Institute of Pharmacology and Neurosciences, Institute of Molecular Medicine, University of Lisbon, 1649-028 Lisbon, Portugal.
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23
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Pankratov Y, Lalo U, Krishtal OA, Verkhratsky A. P2X receptors and synaptic plasticity. Neuroscience 2008; 158:137-48. [PMID: 18495357 DOI: 10.1016/j.neuroscience.2008.03.076] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Revised: 03/09/2008] [Accepted: 03/17/2008] [Indexed: 01/15/2023]
Abstract
Adenosine triphosphate (ATP) is released in many synapses in the CNS either together with other neurotransmitters, such as glutamate and GABA, or on its own. Postsynaptic action of ATP is mediated through metabotropic P2Y and ionotropic P2X receptors abundantly expressed in neural cells. Activation of P2X receptors induces fast excitatory postsynaptic currents in synapses located in various brain regions, including medial habenula, hippocampus and cortex. P2X receptors display relatively high Ca2+ permeability and can mediate substantial Ca2+ influx at resting membrane potential. P2X receptors can dynamically interact with other neurotransmitter receptors, including N-methyl-D-aspartate (NMDA) receptors, GABA(A) receptors and nicotinic acetylcholine (ACh) receptors. Activation of P2X receptors has multiple modulatory effects on synaptic plasticity, either inhibiting or facilitating the long-term changes of synaptic strength depending on physiological context. At the same time precise mechanisms of P2X-dependent regulation of synaptic plasticity remain elusive. Further understanding of the role of P2X receptors in regulation of synaptic transmission in the CNS requires dissection of P2X-mediated effects on pre-synaptic terminals, postsynaptic membrane and glial cells.
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Affiliation(s)
- Y Pankratov
- The University of Warwick, Department of Biological Sciences, Gibbet Hill Road, Coventry CV4 7AL, UK
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24
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Chen JF, Sonsalla PK, Pedata F, Melani A, Domenici MR, Popoli P, Geiger J, Lopes LV, de Mendonça A. Adenosine A2A receptors and brain injury: Broad spectrum of neuroprotection, multifaceted actions and “fine tuning” modulation. Prog Neurobiol 2007; 83:310-31. [DOI: 10.1016/j.pneurobio.2007.09.002] [Citation(s) in RCA: 180] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2007] [Revised: 08/10/2007] [Accepted: 09/21/2007] [Indexed: 10/22/2022]
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25
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Duarte JMN, Oses JP, Rodrigues RJ, Cunha RA. Modification of purinergic signaling in the hippocampus of streptozotocin-induced diabetic rats. Neuroscience 2007; 149:382-91. [PMID: 17869435 DOI: 10.1016/j.neuroscience.2007.08.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2007] [Revised: 07/26/2007] [Accepted: 07/26/2007] [Indexed: 10/23/2022]
Abstract
Diabetic encephalopathy is a recognized complication of untreated diabetes resulting in a progressive cognitive impairment accompanied by modification of hippocampal function. The purinergic system is a promising novel target to control diabetic encephalopathy since it might simultaneously control hippocampal synaptic plasticity and glucose handling. We now tested whether streptozotocin-induced diabetes led to a modification of extracellular ATP homeostasis and density of membrane ATP (P2) receptors in the hippocampus, a brain structure involved in learning and memory. The extracellular levels of ATP, evaluated in the cerebrospinal fluid, were reduced by 60.4+/-17.0% in diabetic rats. Likewise, the evoked release of ATP as well as its extracellular catabolism was also decreased in hippocampal nerve terminals of diabetic rats by 52.8+/-10.9% and 38.7+/-6.5%, respectively. Western blot analysis showed that the density of several P2 receptors (P2X(3,5,7) and P2Y(2,6,11)) was decreased in hippocampal nerve terminals. This indicates that the synaptic ATP signaling is globally depressed in diabetic rats, which may contribute for diabetes-associated decrease of synaptic plasticity. In contrast, the density of P2 receptors (P2X(1,2,5,6,7) and P2Y(6) but not P2Y(2)) increased in whole hippocampal membranes, suggesting an adaptation of non-synaptic P2 receptors to sense decreased levels of extracellular ATP in diabetic rats, which might be aimed at preserving the non-synaptic purinergic signaling.
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Affiliation(s)
- J M N Duarte
- Centre for Neurosciences of Coimbra, Faculty of Medicine, Institute of Biochemistry, University of Coimbra, 3004-504 Coimbra, Portugal.
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Sperlágh B, Zsilla G, Baranyi M, Illes P, Vizi ES. Purinergic modulation of glutamate release under ischemic-like conditions in the hippocampus. Neuroscience 2007; 149:99-111. [PMID: 17850981 DOI: 10.1016/j.neuroscience.2007.07.035] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2007] [Accepted: 08/23/2007] [Indexed: 01/06/2023]
Abstract
The aim of the present study was to explore whether endogenous activation of different purine receptors by ATP and adenosine contributes to or inhibits excess glutamate release evoked by ischemic-like conditions in rat hippocampal slices. Combined oxygen-glucose deprivation (OGD) elicited a substantial, [Ca(2+)](o)-independent release of [(3)H]glutamate, which was tetrodotoxin (1 microM)-sensitive and temperature-dependent. The P2 receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS, 0.1-10 microM), and the selective P2X(7) receptor antagonist Brilliant Blue G (1-100 nM), decreased OGD-evoked [(3)H]glutamate efflux indicating that endogenous ATP facilitates ischemia-evoked glutamate release. The selective A(1)-receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX, 0.1-250 nM) and the selective A(2A) receptor antagonists 4-(2-[7-amino-2-)2-furyl(triazolo-[1,3,5]triazin-5-ylamino]ethyl)phenol (ZM241385, 0.1-20 nM) and 7-(2-phenylethyl)-5-amino-2-(2-furyl)-pyrazolo-[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine (SCH58261, 2-100 nM) decreased OGD-evoked [(3)H]glutamate efflux, indicating that endogenous adenosine also facilitates glutamate release under these conditions. The effect of DPCPX and ZM241385 was reversed, whereas the action of P2 receptor antagonists was potentiated by the selective ecto-ATPase inhibitor 6-N,N-diethyl-D-beta,gamma-dibromomethyleneATP (ARL67156, 50 microM). The binding characteristic of the A(2A) ligand [(3)H]CGS21680 to hippocampal membranes did not change significantly in response to OGD. Taken together these data suggest that while A(1) receptors might became desensitized, A(2A) and P2X receptor-mediated facilitation of glutamate release by endogenous ATP and its breakdown product adenosine remains operational under long-term OGD. Therefore the inhibition of P2X/A(2A) receptors rather than the stimulation of A(1) adenosine receptors could be an effective approach to attenuate glutamatergic excitotoxicity and thereby counteract ischemia-induced neurodegeneration.
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Affiliation(s)
- B Sperlágh
- Department of Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, H-1450 Budapest, Szigony u. 43., Hungary.
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27
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Bjelobaba I, Stojiljkovic M, Pekovic S, Dacic S, Lavrnja I, Stojkov D, Rakic L, Nedeljkovic N. Immunohistological Determination of Ecto-nucleoside Triphosphate Diphosphohydrolase1 (NTPDase1) and 5′-nucleotidase in Rat Hippocampus Reveals Overlapping Distribution. Cell Mol Neurobiol 2007; 27:731-43. [PMID: 17619139 DOI: 10.1007/s10571-007-9159-8] [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] [Received: 12/13/2006] [Accepted: 05/21/2007] [Indexed: 11/29/2022]
Abstract
Distribution of two enzymes involved in the ectonucleotidase enzyme chain, ecto-nucleoside triphosphate diphosphohydrolase1 (NTPDase1) and ecto-5'-nucleotidase, was assessed by immunohistochemistry in the rat hippocampus. Obtained results have shown co-expression of the enzymes in the hippocampal region, as well as wide and strikingly similar cellular distribution. Both enzymes were expressed at the surface of pyramidal neurons in the CA1 and CA2 sections, while cells in the CA3 section were faintly stained. The granule cell layer of the dentate gyrus was moderately stained for NTPDase1, as well as for ecto-5'-nucleotidase. Glial association for ecto-5'-nucleotidase was also observed, and fiber tracts were intensively stained for both enzymes. This is the first comparative study of NTPDase1 and ecto-5'-nucleotidase distribution in the rat hippocampus. Obtained results suggest that the broad overlapping distribution of these enzymes in neurons and glial cells reflects the functional importance of ectonucleotidase actions in the nervous system.
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Affiliation(s)
- Ivana Bjelobaba
- Department of Neurochemistry and Immunonology, Institute for Biological Research Sinisa Stankovic, Belgrade, Serbia
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28
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Cunha RA. Different cellular sources and different roles of adenosine: A1 receptor-mediated inhibition through astrocytic-driven volume transmission and synapse-restricted A2A receptor-mediated facilitation of plasticity. Neurochem Int 2007; 52:65-72. [PMID: 17664029 DOI: 10.1016/j.neuint.2007.06.026] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2007] [Revised: 05/28/2007] [Accepted: 06/04/2007] [Indexed: 12/20/2022]
Abstract
Adenosine is a prototypical neuromodulator, which mainly controls excitatory transmission through the activation of widespread inhibitory A1 receptors and synaptically located A2A receptors. It was long thought that the predominant A1 receptor-meditated modulation by endogenous adenosine was a homeostatic process intrinsic to the synapse. New studies indicate that endogenous extracellular adenosine is originated as a consequence of the release of gliotransmitters, namely ATP, which sets a global inhibitory tonus in brain circuits rather than in a single synapse. Thus, this neuron-glia long-range communication can be viewed as a form of non-synaptic transmission (a concept introduced by Professor Sylvester Vizi), designed to reduce noise in a circuit. This neuron-glia-induced adenosine release is also responsible for exacerbating salient information through A1 receptor-mediated heterosynaptic depression, whereby the activation of a particular synapse recruits a neuron-glia network to generate extracellular adenosine that inhibits neighbouring non-tetanised synapses. In parallel, the local activation of facilitatory A2A receptors by adenosine, formed from ATP released only at high frequencies from neuronal vesicles, down-regulates A1 receptors and facilitates plasticity selectively in the tetanised synapse. Thus, upon high-frequency firing of a given pathway, the combined exacerbation of global A1 receptor-mediated inhibition in the circuit (heterosynaptic depression) with the local synaptic activation of A2A receptors in the activated synapse, cooperate to maximise salience between the activated and non-tetanised synapses.
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Affiliation(s)
- Rodrigo A Cunha
- Center for Neuroscience of Coimbra, Institute of Biochemistry, Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal.
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29
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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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Fresco P, Oliveira JMA, Kunc F, Soares AS, Rocha-Pereira C, Gonçalves J, Diniz C. A2A adenosine-receptor-mediated facilitation of noradrenaline release in rat tail artery involves protein kinase C activation and betagamma subunits formed after alpha2-adrenoceptor activation. Neurochem Int 2007; 51:47-56. [PMID: 17493708 DOI: 10.1016/j.neuint.2007.03.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2007] [Revised: 03/14/2007] [Accepted: 03/19/2007] [Indexed: 11/29/2022]
Abstract
This work aimed to investigate the molecular mechanisms involved in the interaction of alpha2-adrenoceptors and adenosine A2A-receptor-mediated facilitation of noradrenaline release in rat tail artery, namely the type of G-protein involved in this effect and the step or steps where the signalling cascades triggered by alpha2-adrenoceptors and A2A-receptors interact. The selective adenosine A2A-receptor agonist 2-p-(2-carboxy ethyl) phenethylamino-5'-N-ethylcarboxamidoadenosine (CGS 21680; 100 nM) enhanced tritium overflow evoked by trains of 100 pulses at 5 Hz. This effect was abolished by the selective adenosine A2A-receptor antagonist 5-amino-7-(2-phenyl ethyl)-2-(2-furyl)-pyrazolo-[4,3-e]-1,2,4-triazolo [1,5-c]pyrimidine (SCH 58261; 20 nM) and by yohimbine (1 microM). CGS 21680-mediated effects were also abolished by drugs that disrupted G(i/o)-protein coupling with receptors, PTX (2 microg/ml) or NEM (40 microM), by the anti-G(salpha) peptide (2 microg/ml) anti-G(betagamma) peptide (10 microg/ml) indicating coupling of A2A-receptors to G(salpha) and suggesting a crucial role for G(betagamma) subunits in the A(2A)-receptor-mediated enhancement of tritium overflow. Furthermore, phorbol 12-myristate 13-acetate (PMA; 1 microM) or forskolin (1 microM), direct activators of protein kinase C and of adenylyl cyclase, respectively, also enhanced tritium overflow. In addition, PMA-mediated effects were not observed in the presence of either yohimbine or PTX. Results indicate that facilitatory adenosine A2A-receptors couple to G(salpha) subunits which is essential, but not sufficient, for the release facilitation to occur, requiring the involvement of G(i/o)-protein coupling (it disappears after disruption of G(i/o)-protein coupling, PTX or NEM) and/or G(betagamma) subunits (anti-G(betagamma)). We propose a mechanism for the interaction in study suggesting group 2 AC isoforms as a plausible candidate for the interaction site, as these isoforms can integrate inputs from G(salpha) subunits (released after adenosine A2A-receptor activation; prime-activation), G(betagamma) subunits (released after activation of G(i/o)-protein coupled receptors) which can directly synergistically stimulate the prime-activated AC or indirectly via G(betagamma) activation of the PLC-PKC pathway.
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MESH Headings
- Adenylyl Cyclases/drug effects
- Adenylyl Cyclases/metabolism
- Adrenergic Agonists/pharmacology
- Adrenergic Antagonists/pharmacology
- Animals
- Arteries/drug effects
- Arteries/innervation
- Arteries/metabolism
- Enzyme Activation/drug effects
- Enzyme Activation/physiology
- GTP-Binding Protein beta Subunits/biosynthesis
- GTP-Binding Protein beta Subunits/drug effects
- GTP-Binding Protein gamma Subunits/biosynthesis
- GTP-Binding Protein gamma Subunits/drug effects
- Male
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/innervation
- Muscle, Smooth, Vascular/metabolism
- Norepinephrine/metabolism
- Protein Kinase C/drug effects
- Protein Kinase C/metabolism
- Protein Subunits/drug effects
- Protein Subunits/metabolism
- Rats
- Rats, Wistar
- Receptor Cross-Talk/drug effects
- Receptor Cross-Talk/physiology
- Receptor, Adenosine A2A/drug effects
- Receptor, Adenosine A2A/metabolism
- Receptors, Adrenergic, alpha-2/drug effects
- Receptors, Adrenergic, alpha-2/metabolism
- Receptors, G-Protein-Coupled/drug effects
- Receptors, G-Protein-Coupled/metabolism
- Signal Transduction/drug effects
- Signal Transduction/physiology
- Sympathetic Fibers, Postganglionic/drug effects
- Sympathetic Fibers, Postganglionic/metabolism
- Tail/blood supply
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Affiliation(s)
- Paula Fresco
- Serviço de Farmacologia, REQUIMTE/FARMA, Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha, 164, P 4050-047 Porto, Portugal.
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31
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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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32
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Ahmad S, Ahmad A, White CW. Purinergic signaling and kinase activation for survival in pulmonary oxidative stress and disease. Free Radic Biol Med 2006; 41:29-40. [PMID: 16781450 DOI: 10.1016/j.freeradbiomed.2006.03.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2005] [Revised: 02/27/2006] [Accepted: 03/02/2006] [Indexed: 10/24/2022]
Abstract
Stimulus-induced release of endogenous ATP into the extracellular milieu has been shown to occur in a variety of cells, tissues, and organs. Extracellular ATP can propagate signals via P2 receptors that are essential for growth and survival of cells. Abundance of P2 receptors, their multiple isoforms, and their ubiquitous distribution indicate that they transmit vital signals. Pulmonary epithelium and endothelium are rich in both P2X and P2Y receptors. ATP release from lung tissue and cells occurs upon stimulation both in vivo and in vitro. Extracellular ATP can activate signaling cascades composed of protein kinases including extracellular signal-regulated kinase (ERK) and phosphatidylinositol-3-kinase (PI3K). Here we summarize progress related to release of endogenous ATP and nucleotide signaling in pulmonary tissues upon exposure to oxidant stress. Hypoxic, hyperoxic, and ozone exposures cause a rapid increase of extracellular ATP in primary pulmonary endothelial and epithelial cells. Extracellular ATP is critical for survival of these cells in high oxygen and ozone concentrations. The released ATP, upon binding to its specific receptors, triggers ERK and PI3K signaling and renders cells resistant to these stresses. Impairment of ATP release and transmission of such signals could limit cellular survival under oxidative stress. This may further contribute to disease pathogenesis or exacerbation.
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Affiliation(s)
- Shama Ahmad
- Department of Pediatrics, National Jewish Medical and Research Center, 1400 Jackson Street, Denver, CO 80206, USA.
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33
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Abstract
Activity-dependent release of ATP from synapses, axons and glia activates purinergic membrane receptors that modulate intracellular calcium and cyclic AMP. This enables glia to detect neural activity and communicate among other glial cells by releasing ATP through membrane channels and vesicles. Through purinergic signalling, impulse activity regulates glial proliferation, motility, survival, differentiation and myelination, and facilitates interactions between neurons, and vascular and immune system cells. Interactions among purinergic, growth factor and cytokine signalling regulate synaptic strength, development and responses to injury. We review the involvement of ATP and adenosine receptors in neuron-glia signalling, including the release and hydrolysis of ATP, how the receptors signal, the pharmacological tools used to study them, and their functional significance.
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Affiliation(s)
- R Douglas Fields
- National Institute of Child Health and Human Development, National Institutes of Health, Building 35, Room 2A211, MSC 3713, 35 Lincoln Drive, Bethesda, Maryland 20892, USA.
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Melnik S, Wright M, Tanner JA, Tsintsadze T, Tsintsadze V, Miller AD, Lozovaya N. Diadenosine polyphosphate analog controls postsynaptic excitation in CA3-CA1 synapses via a nitric oxide-dependent mechanism. J Pharmacol Exp Ther 2006; 318:579-88. [PMID: 16709679 DOI: 10.1124/jpet.105.097642] [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: 11/22/2022] Open
Abstract
Previously, we have described the modulatory effect of diadenosine polyphosphates Ap4A and Ap5A on synaptic transmission in the rat hippocampal slices mediated by presynaptic receptors (Klishin et al., 1994). In contrast, we now describe how nonhydrolyzable Ap4A analog diadenosine-5',5'''-P1,P4-[beta,beta'-methylene]tetraphosphate (AppCH2ppA) at low micromolar concentrations exerts strong nondesensitizing inhibition of orthodromically evoked field potentials (OFPs) without affecting the amplitude of excitatory postsynaptic currents and antidromically evoked field potentials, as recorded in hippocampal CA1 zone. The effects of AppCH2ppA on OFPs are eliminated by a P2 receptor antagonist pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS) but not mimicked by purinoceptor agonists alpha,beta-methylene-ATP and adenosine 5'-O-(3-thio)-triphosphate, indicating that a P2-like receptor is involved but not one belonging to the conventional P2X/P2Y receptor classes. Diadenosine polyphosphate receptor (P4) antagonist Ip4I (diinosine tetraphosphate) was unable to modulate AppCH2ppA effects. Thus, the PPADS-sensitive P2-like receptor for AppCH2ppA seems to control selectively dendritic excitation of the CA1 neurons. The specific nitric oxide (NO)-scavenger 2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide is shown to significantly attenuate AppCH2ppA-mediated inhibitory effects, indicating that NO is involved in the cascade of events initiated by AppCH2ppA. Further downstream mediation by adenosine A1 receptors is also demonstrated. Hence, AppCH2ppA-mediated effects involve PPADS-sensitive P2-like receptor activation leading to the production of NO that stimulates intracellular synthesis of adenosine, causing in turn postsynaptic A1 receptor activation and subsequent postsynaptic CA1 dendritic inhibition. Such spatially selective postsynaptic dendritic inhibition may influence dendritic electrogenesis in pyramidal neurons and consequently mediate control of neuronal network activity.
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Affiliation(s)
- Sergei Melnik
- Department of Cellular Membranology, Bogomoletz Institute of Physiology, Kiev, Ukraine, Russia
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35
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Franke H, Krügel U, Illes P. P2 receptors and neuronal injury. Pflugers Arch 2006; 452:622-44. [PMID: 16645849 DOI: 10.1007/s00424-006-0071-8] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2006] [Accepted: 03/09/2006] [Indexed: 02/08/2023]
Abstract
Extracellular adenosine 5'-triphosphate (ATP) was proposed to be an activity-dependent signaling molecule that regulates glia-glia and glia-neuron communications. ATP is a neurotransmitter of its own right and, in addition, a cotransmitter of other classical transmitters such as glutamate or GABA. The effects of ATP are mediated by two receptor families belonging either to the P2X (ligand-gated cationic channels) or P2Y (G protein-coupled receptors) types. P2X receptors are responsible for rapid synaptic responses, whereas P2Y receptors mediate slow synaptic responses and other types of purinergic signaling involved in neuronal damage/regeneration. ATP may act at pre- and postsynaptic sites and therefore, it may participate in the phenomena of long-term potentiation and long-term depression of excitatory synaptic transmission. The release of ATP into the extracellular space, e.g., by exocytosis, membrane transporters, and connexin hemichannels, is a widespread physiological process. However, ATP may also leave cells through their plasma membrane damaged by inflammation, ischemia, and mechanical injury. Functional responses to the activation of multiple P2 receptors were found in neurons and glial cells under normal and pathophysiological conditions. P2 receptor-activation could either be a cause or a consequence of neuronal cell death/glial activation and may be related to detrimental and/or beneficial effects. The present review aims at demonstrating that purinergic mechanisms correlate with the etiopathology of brain insults, especially because of the massive extracellular release of ATP, adenosine, and other neurotransmitters after brain injury. We will focus in this review on the most important P2 receptor-mediated neurodegenerative and neuroprotective processes and their beneficial modulation by possible therapeutic manipulations.
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Affiliation(s)
- Heike Franke
- Rudolf-Boehm Institute of Pharmacology and Toxicology, University of Leipzig, Härtelstrasse 16-18, 04107, Leipzig, Germany.
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36
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Abstract
The concept of a purinergic signaling system, using purine nucleotides and nucleosides as extracellular messengers, was first proposed over 30 years ago. After a brief introduction and update of purinoceptor subtypes, this article focuses on the diverse pathophysiological roles of purines and pyrimidines as signaling molecules. These molecules mediate short-term (acute) signaling functions in neurotransmission, mechanosensory transduction, secretion and vasodilatation, and long-term (chronic) signaling functions in cell proliferation, differentiation, and death involved in development and regeneration. Plasticity of purinoceptor expression in pathological conditions is frequently observed, including an increase in the purinergic component of autonomic cotransmission. Recent advances in therapies using purinergic-related drugs in a wide range of pathological conditions will be addressed with speculation on future developments in the field.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, Royal Free and University College Medical School, London NW3 2PF, UK.
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37
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Correia-de-Sá P, Adães S, Timóteo MA, Vieira C, Magalhães-Cardoso T, Nascimento C, Duarte-Araújo M. Fine-tuning modulation of myenteric motoneurons by endogenous adenosine: on the role of secreted adenosine deaminase. Auton Neurosci 2006; 126-127:211-24. [PMID: 16563876 DOI: 10.1016/j.autneu.2006.02.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2005] [Accepted: 02/15/2006] [Indexed: 11/30/2022]
Abstract
Besides the well-characterized inhibitory effect of adenosine in the gastrointestinal tract mediated by A1 receptors, we recently demonstrated that endogenously generated adenosine facilitates [3H]acetylcholine release from myenteric neurons through preferential activation of prejunctional A2A receptors. The co-existence of both receptor subtypes on cholinergic neurons prompted the question of how does adenosine discriminate between these receptors to regulate synaptic transmission in the longitudinal muscle-myenteric plexus (LM-MP) of the rat ileum. Electrical stimulation of the LM-MP increased the outflow of adenosine, inosine and hypoxanthine. Myenteric neurons seem to be the main source of endogenous adenosine, since blockade of action potentials with tetrodotoxin (1 microM) or omission of Ca2+ (plus EGTA, 1 mM) in the buffer essentially abolished nucleosides release, while adenosine outflow remained unchanged when smooth muscle contractions were prevented by nifedipine (1 microM). Inhibition of ecto-5'-nucleotidase by concanavalin A (0.1 mg ml-1) produced only a moderate decrease (approximately 25%) on adenosine accumulation in the LM-MP, indicating that the extracellular catabolism of released ATP might not be a major source of the nucleoside. Data using the acetylcholinesterase inhibitor, physiostigmine (10 microM), and several subtype-specific muscarinic receptor antagonists, 4-DAMP (100 nM), AF-DX 116 (10 microM) and muscarinic toxin-7 (1 nM), suggest that cholinergic motoneurons are endowed with muscarinic M3 autoreceptors facilitating the outflow of adenosine. Surprisingly, bath samples collected after stimulating the LM-MP exhibited a relatively high adenosine deaminase (ADA) activity (0.60+/-0.07 U ml-1), which increased in parallel with the accumulation of adenosine and its deamination products. Our findings are in keeping with the hypothesis that ADA secretion, along with a less-efficient dipyridamole-sensitive nucleoside transport system, may restrict endogenous adenosine actions to the synaptic region channelling to facilitatory A2A receptors activation. Such a local environment may also limit diffusion of exogenously added adenosine towards the active zones, as we showed that this constrain may be overcome by inhibiting ADA activity with erythro-9(2-hydroxy-3-nonyl) adenine (50 microM).
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Affiliation(s)
- Paulo Correia-de-Sá
- Laboratório de Farmacologia/UMIB, Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto, L. Prof. Abel Salazar, 2, 4099-003 Porto, Portugal.
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38
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Rodrigues RJ, Almeida T, Richardson PJ, Oliveira CR, Cunha RA. Dual presynaptic control by ATP of glutamate release via facilitatory P2X1, P2X2/3, and P2X3 and inhibitory P2Y1, P2Y2, and/or P2Y4 receptors in the rat hippocampus. J Neurosci 2006; 25:6286-95. [PMID: 16000618 PMCID: PMC6725280 DOI: 10.1523/jneurosci.0628-05.2005] [Citation(s) in RCA: 175] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
ATP is released in a vesicular manner from nerve terminals mainly at higher stimulation frequencies. There is a robust expression of ATP (P2) receptors in the brain, but their role is primarily unknown. We report that ATP analogs biphasically modulate the evoked release of glutamate from purified nerve terminals of the rat hippocampus, the facilitation being mediated by P2X1, P2X2/3, and P2X3 [antagonized by 8-(benzamido)naphthalene-1,3,5-trisulfonate and 2',3'-O-(2,4,6-trinitrophenyl)-ATP] and the inhibition by P2Y1, P2Y2, and/or P2Y4 [antagonized by reactive blue 2 and 2'deoxy-N6-methyladenosine-3',5'-bisphosphate and mimicked by P1-(urinine 5'-),P4-(inosine 5'-) tetraphosphate and 2-methylthio-ADP] receptors. The combination of single-cell PCR analysis of rat hippocampal pyramidal neurons, Western blot analysis of purified presynaptic active zone fraction, and immunocytochemical analysis of hippocampal glutamatergic terminals revealed that the P2 receptors expressed in glutamatergic neurons, located in the active zone and in glutamatergic terminals, were precisely P2X1, P2X2, and P2X3 subunits and P2Y1, P2Y2, and P2Y4 receptors. This provides coincident functional and molecular evidence that P2 receptors are present and act presynaptically as a modulatory system controlling hippocampal glutamate release.
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MESH Headings
- Adenosine Diphosphate/analogs & derivatives
- Adenosine Diphosphate/pharmacology
- Adenosine Triphosphate/analogs & derivatives
- Adenosine Triphosphate/pharmacology
- Adenosine Triphosphate/physiology
- Adenylyl Imidodiphosphate/pharmacology
- Animals
- Astrocytoma/metabolism
- Astrocytoma/pathology
- Calcium/analysis
- Cell Line/metabolism
- Cell Line, Tumor/metabolism
- Glutamic Acid/metabolism
- Hippocampus/drug effects
- Hippocampus/metabolism
- Kidney
- Male
- Potassium/pharmacology
- Pyramidal Cells/metabolism
- Pyridoxal Phosphate/analogs & derivatives
- Pyridoxal Phosphate/pharmacology
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- Rats
- Rats, Wistar
- Receptors, Presynaptic/drug effects
- Receptors, Presynaptic/physiology
- Receptors, Purinergic P2/biosynthesis
- Receptors, Purinergic P2/drug effects
- Receptors, Purinergic P2/genetics
- Receptors, Purinergic P2/physiology
- Receptors, Purinergic P2X
- Receptors, Purinergic P2X2
- Receptors, Purinergic P2X3
- Receptors, Purinergic P2Y1
- Receptors, Purinergic P2Y2
- Recombinant Fusion Proteins/biosynthesis
- Subcellular Fractions/metabolism
- Suramin/analogs & derivatives
- Suramin/pharmacology
- Synaptosomes/chemistry
- Synaptosomes/metabolism
- Transfection
- Triazines/pharmacology
- Triazoles/pharmacology
- Xanthines/pharmacology
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Affiliation(s)
- Ricardo J Rodrigues
- Centre for Neurosciences of Coimbra, Institute of Biochemistry, Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal
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Dulla CG, Dobelis P, Pearson T, Frenguelli BG, Staley KJ, Masino SA. Adenosine and ATP link PCO2 to cortical excitability via pH. Neuron 2005; 48:1011-23. [PMID: 16364904 PMCID: PMC1924599 DOI: 10.1016/j.neuron.2005.11.009] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2005] [Revised: 08/11/2005] [Accepted: 11/05/2005] [Indexed: 11/28/2022]
Abstract
In addition to affecting respiration and vascular tone, deviations from normal CO(2) alter pH, consciousness, and seizure propensity. Outside the brainstem, however, the mechanisms by which CO(2) levels modify neuronal function are unknown. In the hippocampal slice preparation, increasing CO(2), and thus decreasing pH, increased the extracellular concentration of the endogenous neuromodulator adenosine and inhibited excitatory synaptic transmission. These effects involve adenosine A(1) and ATP receptors and depend on decreased extracellular pH. In contrast, decreasing CO(2) levels reduced extracellular adenosine concentration and increased neuronal excitability via adenosine A(1) receptors, ATP receptors, and ecto-ATPase. Based on these studies, we propose that CO(2)-induced changes in neuronal function arise from a pH-dependent modulation of adenosine and ATP levels. These findings demonstrate a mechanism for the bidirectional effects of CO(2) on neuronal excitability in the forebrain.
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Affiliation(s)
- Chris G Dulla
- Neuroscience Program, Department of Neurology, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA
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40
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Fredholm BB, Chen JF, Masino SA, Vaugeois JM. ACTIONS OF ADENOSINE AT ITS RECEPTORS IN THE CNS: Insights from Knockouts and Drugs. Annu Rev Pharmacol Toxicol 2005; 45:385-412. [PMID: 15822182 DOI: 10.1146/annurev.pharmtox.45.120403.095731] [Citation(s) in RCA: 264] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Adenosine and its receptors have been the topic of many recent reviews ( 1 – 26 ). These reviews provide a good summary of much of the relevant literature—including the older literature. We have, therefore, chosen to focus the present review on the insights gained from recent studies on genetically modified mice, particularly with respect to the function of adenosine receptors and their potential as therapeutic targets. The information gained from studies of drug effects is discussed in this context, and discrepancies between genetic and pharmacological results are highlighted.
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Affiliation(s)
- Bertil B Fredholm
- Department of Physiology and Pharmacology, Karolinska Institutet, S-17177 Stockholm, Sweden
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41
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da Silva BM, de Mendonça A, Ribeiro JA. Long-term depression is not modulated by ATP receptors in the rat CA1 hippocampal region. Neurosci Lett 2005; 383:345-9. [PMID: 15882930 DOI: 10.1016/j.neulet.2005.04.051] [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: 03/24/2005] [Revised: 04/18/2005] [Accepted: 04/19/2005] [Indexed: 11/23/2022]
Abstract
ATP is an important extracellular messenger in the CNS. In the hippocampus, a brain structure relevant for learning and memory processes, it acts both as a modulator and as a mediator of synaptic transmission, with implications for synaptic plasticity phenomena. Recent evidence suggests that ATP modulates activity-dependent long-term potentiation (LTP) of Schaffer collateral-CA1 synapses. However, it remains unclear if ATP also modulates LTP counterpart's phenomenon, long-term depression (LTD), in the rat hippocampus. This study investigated the effect of ATP analogues on homosynaptic LTD, induced by low-frequency stimulation of the Schaffer collaterals (1 Hz; 900 pulses) in the CA1 region of young rat hippocampal slices. The metabolically stable ATP analogues beta,gamma-ImATP (20 microM), a P2 receptor agonist, and alpha,beta-MeATP (20 microM), a preferential P2X(1,3) receptor agonist, did not modify LTD (LTD values of 14.7+/-0.5% and 14.1+/-3% for aCSF controls and of 15.1+/-4% and 19.0+/-5.2% for beta,gamma-ImATP and alpha,beta-MeATP, respectively). The ATP analogue beta,gamma-ImATP (20 microM) did not modify LTD also in the presence of the adenosine A1 receptor antagonist DPCPX (50 nM) (21.5+/-4.2% for DPCPX only and of 23.8+/-8.9% for DPCPX plus beta,gamma-ImATP). Finally, the preferential P2X(1,3) receptor antagonist NF023 (10 microM) had also no effect on LTD (18.6+/-5.2% for aCSF and of 18.7+/-5.2% for NF023). The present results suggest that ATP does not modulate activity-dependent homosynaptic LTD in the rat CA1 hippocampal region by activating P2 receptors.
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Affiliation(s)
- Bruno M da Silva
- Laboratory of Neurosciences, Institute of Molecular Medicine and Faculty of Medicine of Lisbon, Lisbon, Portugal.
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42
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Rebola N, Canas PM, Oliveira CR, Cunha RA. Different synaptic and subsynaptic localization of adenosine A2A receptors in the hippocampus and striatum of the rat. Neuroscience 2005; 132:893-903. [PMID: 15857695 DOI: 10.1016/j.neuroscience.2005.01.014] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2004] [Revised: 01/03/2005] [Accepted: 01/06/2005] [Indexed: 11/30/2022]
Abstract
Adenosine A(2A) receptors are most abundant in the striatum where they control the striatopallidal pathway thus controlling locomotion. Extra-striatal A(2A) receptors are considerably less abundant but their blockade confers robust neuroprotection. We now have investigated if striatal and extra-striatal A(2A) receptors have a different neuronal location to understand their different functions. The binding density of the A(2A) antagonist, [(3)H]-7-(2-phenylethyl)-5-amino-2-(2-furyl)pyrazolo[4,3e][1,2,4]triazolo[1,5-c]pyrimidine ([(3)H]SCH 58261), was enriched in nerve terminals membranes (B(max)=103+/-12 fmol/mg protein) compared with total membranes (B(max)=29+/-4 fmol/mg protein) from the hippocampus, the same occurring with A(2A) receptor immunoreactivity. In contrast, there was no enrichment of [(3)H]SCH 58261 binding or A(2A) receptor immunoreactivity in synaptosomal compared with total membranes from the striatum. Further subcellular fractionation of hippocampal nerve terminals revealed that A(2A) receptor immunoreactivity was enriched in the active zone of presynaptic nerve terminals, whereas it was predominantly located in the postsynaptic density in the striatum, although a minority of striatal A(2A) receptors were located in the presynaptic active zone. These results indicate that A(2A) receptors in the striatum are not enriched in synapses in agreement with the preponderant role of A(2A) receptors in signal processing in striatopallidal neurons. In contrast, hippocampal A(2A) receptors are enriched in synapses, mainly in the active zone, in accordance with their role in controlling neurotransmitter release. This regional variation in the neuronal distribution of A(2A) receptors reinforces the care required to extrapolate our knowledge from striatal A(2A) receptors to other brain preparations.
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Affiliation(s)
- N Rebola
- Center for Neurosciences of Coimbra, Institute of Biochemistry, Faculty of Medicine, University of Coimbra, Portugal
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43
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Burnstock G, Knight GE. Cellular Distribution and Functions of P2 Receptor Subtypes in Different Systems. INTERNATIONAL REVIEW OF CYTOLOGY 2004; 240:31-304. [PMID: 15548415 DOI: 10.1016/s0074-7696(04)40002-3] [Citation(s) in RCA: 573] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This review is aimed at providing readers with a comprehensive reference article about the distribution and function of P2 receptors in all the organs, tissues, and cells in the body. Each section provides an account of the early history of purinergic signaling in the organ?cell up to 1994, then summarizes subsequent evidence for the presence of P2X and P2Y receptor subtype mRNA and proteins as well as functional data, all fully referenced. A section is included describing the plasticity of expression of P2 receptors during development and aging as well as in various pathophysiological conditions. Finally, there is some discussion of possible future developments in the purinergic signaling field.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Institute, Royal Free and University College Medical School, London NW3 2PF, United Kingdom
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