1
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Adebiyi OE, Bynoe MS. Roles of Adenosine Receptor (subtypes A 1 and A 2A) in Cuprizone-Induced Hippocampal Demyelination. Mol Neurobiol 2023; 60:5878-5890. [PMID: 37358743 DOI: 10.1007/s12035-023-03440-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 06/10/2023] [Indexed: 06/27/2023]
Abstract
Hippocampal demyelination in multiple sclerosis (MS) has been linked with cognitive deficits, however, patients could benefit from treatment that induces oligodendroglial cell function and promotes remyelination. We investigated the role of A1 and A2A adenosine receptors (AR) in regulating oligodendrocyte precursor cells (OPCs) and myelinating oligodendrocyte (OL) in the demyelinated hippocampus using the cuprizone model of MS. Spatial learning and memory were assessed in wild type C57BL/6 mice (WT) or C57BL/6 mice with global deletion of A1 (A1AR-/-) or A2A AR (A2AAR-/-) fed standard or cuprizone diet (CD) for four weeks. Histology, immunofluorescence, Western blot and TUNEL assays were performed to evaluate the extent of demyelination and apoptosis in the hippocampus. Deletion of A1 and A2A AR alters spatial learning and memory. In A1AR-/- mice, cuprizone feeding led to severe hippocampal demyelination, A2AAR-/- mice had a significant increase in myelin whereas WT mice had intermediate demyelination. The A1AR-/- CD-fed mice displayed significant astrocytosis and decreased expression of NeuN and MBP, whereas these proteins were increased in the A2AAR-/- CD mice. Furthermore, Olig2 was upregulated in A1AR-/- CD-fed mice compared to WT mice fed the standard diet. TUNEL staining of brain sections revealed a fivefold increase in the hippocampus of A1AR-/- CD-fed mice. Also, WT mice fed CD showed a significant decrease expression of A1 AR. A1 and A2A AR are involved in OPC/OL functions with opposing roles in myelin regulation in the hippocampus. Thus, the neuropathological findings seen in MS may be connected to the depletion of A1 AR.
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Affiliation(s)
- Olamide E Adebiyi
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA.
- Department of Veterinary Physiology and Biochemistry, Faculty of Veterinary Medicine, University of Ibadan, Ibadan, Nigeria.
| | - Margaret S Bynoe
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA.
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2
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Haddad M, Cherchi F, Alsalem M, Al-saraireh YM, Madae’en S. Adenosine Receptors as Potential Therapeutic Analgesic Targets. Int J Mol Sci 2023; 24:13160. [PMID: 37685963 PMCID: PMC10487796 DOI: 10.3390/ijms241713160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 08/18/2023] [Accepted: 08/23/2023] [Indexed: 09/10/2023] Open
Abstract
Pain represents an international burden and a major socio-economic public health problem. New findings, detailed in this review, suggest that adenosine plays a significant role in neuropathic and inflammatory pain, by acting on its metabotropic adenosine receptors (A1AR, A2AAR, A2BAR, A3AR). Adenosine receptor ligands have a practical translational potential based on the favorable efficacy and safety profiles that emerged from clinical research on various agonists and antagonists for different pathologies. The present review collects the latest studies on selected adenosine receptor ligands in different pain models. Here, we also covered the many hypothesized pathways and the role of newly synthesized allosteric adenosine receptor modulators. This review aims to present a summary of recent research on adenosine receptors as prospective therapeutic targets for a range of pain-related disorders.
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Affiliation(s)
- Mansour Haddad
- Faculty of Pharmacy, Yarmouk University, Irbid 21163, Jordan
| | - Federica Cherchi
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), Section of Pharmacology and Toxicology, University of Florence, 50139 Florence, Italy;
| | - Mohammad Alsalem
- School of Medicine, The University of Jordan, Amman 11942, Jordan;
| | - Yousef M. Al-saraireh
- Department of Pharmacology, Faculty of Medicine, Mutah University, P.O. Box 7, Al-Karak 61710, Jordan;
| | - Saba Madae’en
- Department of Clinical Pharmacy and Pharmacy Practice, Faculty of Pharmaceutical Sciences, The Hashemite University, Zarqa 13133, Jordan;
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3
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Haddad M, Alsalem M, Aldossary SA, Kalbouneh H, Jaffal SM, Alshawabkeh Q, Al Hayek S, Abdelhai O, Barakat NA, El-Salem K. The role of adenosine receptor ligands on inflammatory pain: possible modulation of TRPV1 receptor function. Inflammopharmacology 2023; 31:337-347. [PMID: 36580157 DOI: 10.1007/s10787-022-01127-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 12/20/2022] [Indexed: 12/30/2022]
Abstract
Chronic pain has a debilitating consequences on health and lifestyle. The currently available analgesics are often ineffective and accompanied by undesirable adverse effects. Although adenosine receptors (AR) activation can affect nociceptive, inflammatory, and neuropathic pain states, the specific regulatory functions of its subtypes (A1, A2A, A2B and A3 ARs) are not fully understood. The aim of this study was to investigate the role of different AR ligands on inflammatory pain. The von Frey filament test was used to assess the anti-nociceptive effects of adenosine ligands on Complete Freund's Adjuvant (CFA)-induced mechanical allodynia in (180-220 g) adult male Sprague Dawley rats (expressed as paw withdrawal threshold, PWT). Neither the A2AAR selective agonist CGS 21680 hydrochloride (0.1, 0.32 and 1 mg/kg) nor the A2BAR selective agonist BAY 60-6583 (0.1, 0.32 and 1 mg/kg) produced any significant reversal of the PWT. However, the A1AR selective agonist ( ±)-5'-Chloro-5'-deoxy-ENBA, the A3AR selective agonist 2-Cl-IB-MECA, the A2AAR selective antagonist ZM 241385 and the A2BAR selective antagonist PSB 603 produced a significant reversal of the PWT at the highest dose of 1 mg/kg. Co-administration of the selective antagonists of A1AR and A3AR PSB36 (1 mg/ml) and MRS-3777 (1 mg/ml); respectively, significantly reversed the anti-nociceptive effects of their corresponding agonists. Furthermore, calcium imaging studies reveled that the effective AR ligands in the behavioral assay also significantly inhibit capsaicin-evoked calcium responses in cultured rat dorsal root ganglia (DRG) neurons. In conclusion, modulating the activity of the transient receptor potential vanilloid 1 (TRPV1) receptor by ARs ligands could explain their anti-nociceptive effects observed in vivo. Therefore, the cross talk between ARs and TRPV1 receptor may represent a promising targets for the treatment of inflammatory pain conditions.
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Affiliation(s)
- Mansour Haddad
- Faculty of Pharmacy, Yarmouk University, Irbid, 21163, Jordan.
| | - Mohammad Alsalem
- School of Medicine, The University of Jordan, Amman, 11942, Jordan
| | - Sara A Aldossary
- Faculty of Clinical Pharmacy, King Faisal University, Al-Ahsa, Saudi Arabia
| | - Heba Kalbouneh
- School of Medicine, The University of Jordan, Amman, 11942, Jordan
| | - Sahar M Jaffal
- Biological Sciences, Faculty of Science, The University of Jordan, Amman, 11942, Jordan
| | | | - Sa'ed Al Hayek
- School of Medicine, The University of Jordan, Amman, 11942, Jordan
| | - Omar Abdelhai
- Al Khalidi Hospital and Medical Center, Ibn Khaldon St.39, Amman, Jordan
| | - Noor A Barakat
- School of Medicine, The University of Jordan, Amman, 11942, Jordan
| | - Khalid El-Salem
- Faculty of Medicine, Jordan University of Science and Technology, Irbid, 22110, Jordan
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4
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Tozaki-Saitoh H, Takeda H, Inoue K. The Role of Microglial Purinergic Receptors in Pain Signaling. Molecules 2022; 27:molecules27061919. [PMID: 35335282 PMCID: PMC8949888 DOI: 10.3390/molecules27061919] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 03/10/2022] [Accepted: 03/14/2022] [Indexed: 12/25/2022] Open
Abstract
Pain is an essential modality of sensation in the body. Purinergic signaling plays an important role in nociceptive pain transmission, under both physiological and pathophysiological conditions, and is important for communication between both neuronal and non-neuronal cells. Microglia and astrocytes express a variety of purinergic effectors, and a variety of receptors play critical roles in the pathogenesis of neuropathic pain. In this review, we discuss our current knowledge of purinergic signaling and of the compounds that modulate purinergic transmission, with the aim of highlighting the importance of purinergic pathways as targets for the treatment of persistent pain.
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Affiliation(s)
- Hidetoshi Tozaki-Saitoh
- Department of Pharmacology, School of Pharmacy at Fukuoka, International University of Health and Welfare, 137-1 Enokizu, Okawa 831-8501, Japan;
- Correspondence: ; Tel.: +81-944-32-6137
| | - Hiroshi Takeda
- Department of Pharmacology, School of Pharmacy at Fukuoka, International University of Health and Welfare, 137-1 Enokizu, Okawa 831-8501, Japan;
| | - Kazuhide Inoue
- Institute for Advanced Study, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan;
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5
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Metzner K, Gross T, Balzulat A, Wack G, Lu R, Schmidtko A. Lack of efficacy of a partial adenosine A1 receptor agonist in neuropathic pain models in mice. Purinergic Signal 2021; 17:503-514. [PMID: 34313915 PMCID: PMC8410902 DOI: 10.1007/s11302-021-09806-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Accepted: 06/28/2021] [Indexed: 12/25/2022] Open
Abstract
Previous studies suggest that adenosine A1 receptors (A1R) modulate the processing of pain. The aim of this study was to characterize the distribution of A1R in nociceptive tissues and to evaluate whether targeting A1R with the partial agonist capadenoson may reduce neuropathic pain in mice. The cellular distribution of A1R in dorsal root ganglia (DRG) and the spinal cord was analyzed using fluorescent in situ hybridization. In behavioral experiments, neuropathic pain was induced by spared nerve injury or intraperitoneal injection of paclitaxel, and tactile hypersensitivities were determined using a dynamic plantar aesthesiometer. Whole-cell patch-clamp recordings were performed to assess electrophysiological properties of dissociated DRG neurons. We found A1R to be expressed in populations of DRG neurons and dorsal horn neurons involved in the processing of pain. However, administration of capadenoson at established in vivo doses (0.03–1.0 mg/kg) did not alter mechanical hypersensitivity in the spared nerve injury and paclitaxel models of neuropathic pain, whereas the standard analgesic pregabalin significantly inhibited the pain behavior. Moreover, capadenoson failed to affect potassium currents in DRG neurons, in contrast to a full A1R agonist. Despite expression of A1R in nociceptive neurons, our data do not support the hypothesis that pharmacological intervention with partial A1R agonists might be a valuable approach for the treatment of neuropathic pain.
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Affiliation(s)
- Katharina Metzner
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany.
| | - Tilman Gross
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
| | - Annika Balzulat
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
| | - Gesine Wack
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
| | - Ruirui Lu
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
| | - Achim Schmidtko
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
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6
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Zyma M, Pawliczak R. Characteristics and the role of purinergic receptors in pathophysiology with focus on immune response. Int Rev Immunol 2020; 39:97-117. [PMID: 32037918 DOI: 10.1080/08830185.2020.1723582] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The nucleotide adenosine-5'-triphosphate (ATP) is mostly thought to be energy carrier, but evidence presented in multiple studies proves ATP involvement into variety of processes, due to its neuromodulatory capabilities. ATP and its metabolite-adenosine, bind to the purinergic receptors, which are divided into two types: adenosine binding P1 receptor and ADP/ATP binding P2 receptor. These receptors are expressed in different tissues and organs. Recent studies report their immunomodulatory characteristics, connected with varying immunological processes, such as immunological response or antigen presentation. Besides, they seem to play an important role in medical conditions such as bronchial asthma or variety of cancers. In this article, we would like to review recent discoveries on the field of purinergic receptors research focusing on their role in immunological system, and shed a new light upon the importance of these receptors in modern medicine development.
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Affiliation(s)
- Marharyta Zyma
- Department of Immunopathology, Division of Biomedical Science, Faculty of Medicine, Medical University of Lodz, Lodz, Poland
| | - Rafał Pawliczak
- Department of Immunopathology, Division of Biomedical Science, Faculty of Medicine, Medical University of Lodz, Lodz, Poland
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7
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Rivera-Oliver M, Moreno E, Álvarez-Bagnarol Y, Ayala-Santiago C, Cruz-Reyes N, Molina-Castro GC, Clemens S, Canela EI, Ferré S, Casadó V, Díaz-Ríos M. Adenosine A 1-Dopamine D 1 Receptor Heteromers Control the Excitability of the Spinal Motoneuron. Mol Neurobiol 2018; 56:797-811. [PMID: 29797183 DOI: 10.1007/s12035-018-1120-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 05/11/2018] [Indexed: 10/16/2022]
Abstract
While the role of the ascending dopaminergic system in brain function and dysfunction has been a subject of extensive research, the role of the descending dopaminergic system in spinal cord function and dysfunction is just beginning to be understood. Adenosine plays a key role in the inhibitory control of the ascending dopaminergic system, largely dependent on functional complexes of specific subtypes of adenosine and dopamine receptors. Combining a selective destabilizing peptide strategy with a proximity ligation assay and patch-clamp electrophysiology in slices from male mouse lumbar spinal cord, the present study demonstrates the existence of adenosine A1-dopamine D1 receptor heteromers in the spinal motoneuron by which adenosine tonically inhibits D1 receptor-mediated signaling. A1-D1 receptor heteromers play a significant control of the motoneuron excitability, represent main targets for the excitatory effects of caffeine in the spinal cord and can constitute new targets for the pharmacological therapy after spinal cord injury, motor aging-associated disorders and restless legs syndrome.
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Affiliation(s)
- Marla Rivera-Oliver
- Department of Anatomy and Neurobiology and Institute of Neurobiology, University of Puerto Rico, Medical Sciences, Rio Piedras and Cayey Campuses, San Juan, 00936, Puerto Rico
| | - Estefanía Moreno
- Center for Biomedical Research in Neurodegenerative Diseases Network (CIBERNED) and Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Institute of Biomedicine of the University of Barcelona, University of Barcelona, 08028, Barcelona, Spain
| | - Yocasta Álvarez-Bagnarol
- Department of Anatomy and Neurobiology and Institute of Neurobiology, University of Puerto Rico, Medical Sciences, Rio Piedras and Cayey Campuses, San Juan, 00936, Puerto Rico
| | - Christian Ayala-Santiago
- Department of Anatomy and Neurobiology and Institute of Neurobiology, University of Puerto Rico, Medical Sciences, Rio Piedras and Cayey Campuses, San Juan, 00936, Puerto Rico
| | - Nicole Cruz-Reyes
- Department of Anatomy and Neurobiology and Institute of Neurobiology, University of Puerto Rico, Medical Sciences, Rio Piedras and Cayey Campuses, San Juan, 00936, Puerto Rico
| | - Gian Carlo Molina-Castro
- Department of Anatomy and Neurobiology and Institute of Neurobiology, University of Puerto Rico, Medical Sciences, Rio Piedras and Cayey Campuses, San Juan, 00936, Puerto Rico
| | - Stefan Clemens
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, 27834, USA
| | - Enric I Canela
- Center for Biomedical Research in Neurodegenerative Diseases Network (CIBERNED) and Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Institute of Biomedicine of the University of Barcelona, University of Barcelona, 08028, Barcelona, Spain
| | - Sergi Ferré
- Integrative Neurobiology Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Triad Technology Building, 333 Cassell Drive, Baltimore, MD, 21224, USA.
| | - Vicent Casadó
- Center for Biomedical Research in Neurodegenerative Diseases Network (CIBERNED) and Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Institute of Biomedicine of the University of Barcelona, University of Barcelona, 08028, Barcelona, Spain
| | - Manuel Díaz-Ríos
- Department of Anatomy and Neurobiology and Institute of Neurobiology, University of Puerto Rico, Medical Sciences, Rio Piedras and Cayey Campuses, San Juan, 00936, Puerto Rico
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8
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Sebastião AM, Rei N, Ribeiro JA. Amyotrophic Lateral Sclerosis (ALS) and Adenosine Receptors. Front Pharmacol 2018; 9:267. [PMID: 29713276 PMCID: PMC5911503 DOI: 10.3389/fphar.2018.00267] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 03/09/2018] [Indexed: 12/11/2022] Open
Abstract
In the present review we discuss the potential involvement of adenosinergic signaling, in particular the role of adenosine receptors, in amyotrophic lateral sclerosis (ALS). Though the literature on this topic is not abundant, the information so far available on adenosine receptors in animal models of ALS highlights the interest to continue to explore the role of these receptors in this neurodegenerative disease. Indeed, all motor neurons affected in ALS are responsive to adenosine receptor ligands but interestingly, there are alterations in pre-symptomatic or early symptomatic stages that mirror those in advanced disease stages. Information starts to emerge pointing toward a beneficial role of A2A receptors (A2AR), most probably at early disease states, and a detrimental role of caffeine, in clear contrast with what occurs in other neurodegenerative diseases. However, some evidence also exists on a beneficial action of A2AR antagonists. It may happen that there are time windows where A2AR prove beneficial and others where their blockade is required. Furthermore, the same changes may not occur simultaneously at the different synapses. In line with this, it is not fully understood if ALS is a dying back disease or if it propagates in a centrifugal way. It thus seems crucial to understand how motor neuron dysfunction occurs, how adenosine receptors are involved in those dysfunctions and whether the early changes in purinergic signaling are compensatory or triggers for the disease. Getting this information is crucial before starting the design of purinergic based strategies to halt or delay disease progression.
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Affiliation(s)
- Ana M Sebastião
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.,Instituto de Medicina Molecular, Universidade de Lisboa, Lisbon, Portugal
| | - Nádia Rei
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.,Instituto de Medicina Molecular, Universidade de Lisboa, Lisbon, Portugal
| | - Joaquim A Ribeiro
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.,Instituto de Medicina Molecular, Universidade de Lisboa, Lisbon, Portugal
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9
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Acton D, Miles GB. Gliotransmission and adenosinergic modulation: insights from mammalian spinal motor networks. J Neurophysiol 2017; 118:3311-3327. [PMID: 28954893 DOI: 10.1152/jn.00230.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Astrocytes are proposed to converse with neurons at tripartite synapses, detecting neurotransmitter release and responding with release of gliotransmitters, which in turn modulate synaptic strength and neuronal excitability. However, a paucity of evidence from behavioral studies calls into question the importance of gliotransmission for the operation of the nervous system in healthy animals. Central pattern generator (CPG) networks in the spinal cord and brain stem coordinate the activation of muscles during stereotyped activities such as locomotion, inspiration, and mastication and may therefore provide tractable models in which to assess the contribution of gliotransmission to behaviorally relevant neural activity. We review evidence for gliotransmission within spinal locomotor networks, including studies indicating that adenosine derived from astrocytes regulates the speed of locomotor activity via metamodulation of dopamine signaling.
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Affiliation(s)
- David Acton
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife , United Kingdom
| | - Gareth B Miles
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife , United Kingdom
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10
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Wu L, Meng J, Shen Q, Zhang Y, Pan S, Chen Z, Zhu LQ, Lu Y, Huang Y, Zhang G. Caffeine inhibits hypothalamic A 1R to excite oxytocin neuron and ameliorate dietary obesity in mice. Nat Commun 2017; 8:15904. [PMID: 28654087 PMCID: PMC5490268 DOI: 10.1038/ncomms15904] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 05/10/2017] [Indexed: 12/14/2022] Open
Abstract
Caffeine, an antagonist of the adenosine receptor A1R, is used as a dietary supplement to reduce body weight, although the underlying mechanism is unclear. Here, we report that adenosine level in the cerebrospinal fluid, and hypothalamic expression of A1R, are increased in the diet-induced obesity (DIO) mouse. We find that mice with overexpression of A1R in the neurons of paraventricular nucleus (PVN) of the hypothalamus are hyperphagic, have glucose intolerance and high body weight. Central or peripheral administration of caffeine reduces the body weight of DIO mice by the suppression of appetite and increasing of energy expenditure. We also show that caffeine excites oxytocin expressing neurons, and blockade of the action of oxytocin significantly attenuates the effect of caffeine on energy balance. These data suggest that caffeine inhibits A1Rs expressed on PVN oxytocin neurons to negatively regulate energy balance in DIO mice.
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Affiliation(s)
- Liufeng Wu
- Key Laboratory of Environmental Health, Ministry of Education, Department of Toxicology, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Jia Meng
- Key Laboratory of Environmental Health, Ministry of Education, Department of Toxicology, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Qing Shen
- Key Laboratory of Environmental Health, Ministry of Education, Department of Toxicology, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Yi Zhang
- Key Laboratory of Environmental Health, Ministry of Education, Department of Toxicology, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Susu Pan
- Key Laboratory of Environmental Health, Ministry of Education, Department of Toxicology, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Zhuo Chen
- Key Laboratory of Environmental Health, Ministry of Education, Department of Toxicology, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Ling-Qiang Zhu
- Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.,Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Youming Lu
- Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.,Department of Physiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Yuan Huang
- Key Laboratory of Environmental Health, Ministry of Education, Department of Toxicology, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Guo Zhang
- Key Laboratory of Environmental Health, Ministry of Education, Department of Toxicology, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.,Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
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11
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Jourdain P, Allaman I, Rothenfusser K, Fiumelli H, Marquet P, Magistretti PJ. L-Lactate protects neurons against excitotoxicity: implication of an ATP-mediated signaling cascade. Sci Rep 2016; 6:21250. [PMID: 26893204 PMCID: PMC4759786 DOI: 10.1038/srep21250] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 01/20/2016] [Indexed: 12/20/2022] Open
Abstract
Converging experimental data indicate a neuroprotective action of L-Lactate. Using Digital Holographic Microscopy, we observe that transient application of glutamate (100 μM; 2 min) elicits a NMDA-dependent death in 65% of mouse cortical neurons in culture. In the presence of L-Lactate (or Pyruvate), the percentage of neuronal death decreases to 32%. UK5099, a blocker of the Mitochondrial Pyruvate Carrier, fully prevents L-Lactate-mediated neuroprotection. In addition, L-Lactate-induced neuroprotection is not only inhibited by probenicid and carbenoxolone, two blockers of ATP channel pannexins, but also abolished by apyrase, an enzyme degrading ATP, suggesting that ATP produced by the Lactate/Pyruvate pathway is released to act on purinergic receptors in an autocrine/paracrine manner. Finally, pharmacological approaches support the involvement of the P2Y receptors associated to the PI3-kinase pathway, leading to activation of KATP channels. This set of results indicates that L-Lactate acts as a signalling molecule for neuroprotection against excitotoxicity through coordinated cellular pathways involving ATP production, release and activation of a P2Y/KATP cascade.
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Affiliation(s)
- P Jourdain
- Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.,Centre de Neurosciences Psychiatriques, CHUV, Département de Psychiatrie, Site de Cery, CH-1008 Prilly/Lausanne, Switzerland
| | - I Allaman
- Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - K Rothenfusser
- Centre de Neurosciences Psychiatriques, CHUV, Département de Psychiatrie, Site de Cery, CH-1008 Prilly/Lausanne, Switzerland
| | - H Fiumelli
- King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia
| | - P Marquet
- Centre de Neurosciences Psychiatriques, CHUV, Département de Psychiatrie, Site de Cery, CH-1008 Prilly/Lausanne, Switzerland
| | - P J Magistretti
- Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.,King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia.,Centre de Neurosciences Psychiatriques, CHUV, Département de Psychiatrie, Site de Cery, CH-1008 Prilly/Lausanne, Switzerland
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12
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Deuchars SA, Lall VK. Sympathetic preganglionic neurons: properties and inputs. Compr Physiol 2016; 5:829-69. [PMID: 25880515 DOI: 10.1002/cphy.c140020] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The sympathetic nervous system comprises one half of the autonomic nervous system and participates in maintaining homeostasis and enabling organisms to respond in an appropriate manner to perturbations in their environment, either internal or external. The sympathetic preganglionic neurons (SPNs) lie within the spinal cord and their axons traverse the ventral horn to exit in ventral roots where they form synapses onto postganglionic neurons. Thus, these neurons are the last point at which the central nervous system can exert an effect to enable changes in sympathetic outflow. This review considers the degree of complexity of sympathetic control occurring at the level of the spinal cord. The morphology and targets of SPNs illustrate the diversity within this group, as do their diverse intrinsic properties which reveal some functional significance of these properties. SPNs show high degrees of coupled activity, mediated through gap junctions, that enables rapid and coordinated responses; these gap junctions contribute to the rhythmic activity so critical to sympathetic outflow. The main inputs onto SPNs are considered; these comprise afferent, descending, and interneuronal influences that themselves enable functionally appropriate changes in SPN activity. The complexity of inputs is further demonstrated by the plethora of receptors that mediate the different responses in SPNs; their origins and effects are plentiful and diverse. Together these different inputs and the intrinsic and coupled activity of SPNs result in the rhythmic nature of sympathetic outflow from the spinal cord, which has a variety of frequencies that can be altered in different conditions.
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Affiliation(s)
- Susan A Deuchars
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
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Deuchars SA. How sympathetic are your spinal cord circuits? Exp Physiol 2015; 100:365-71. [PMID: 25655449 DOI: 10.1113/ep085031] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 01/29/2015] [Indexed: 12/21/2022]
Abstract
NEW FINDINGS What is the topic of this review? This review focuses on the role of gap junctions and interneurones in sympathetic control at the spinal cord level. What advances does it highlight? The review considers the importance of these local spinal circuits in contributing to rhythmic autonomic activity and enabling appropriate responses to homeostatic perturbations. Sympathetic control of end organs relies on the activity of sympathetic preganglionic neurones (SPNs) within the spinal cord. These SPNs exhibit heterogeneity with respect to function, neurochemistry, location, descending inputs and patterns of activity. Part of this heterogeneity is bestowed by local spinal circuitry. Our understanding of the role of these local circuits, including the significance of connections between the SPNs themselves through specialized gap junctions, is patchy. This report focuses on interneurones and gap junctions within these circuits. Gap junctions play a role in sympathetic control; they are located on SPNs in the intermediolateral cell column. Mefloquine, a chemical that blocks these gap junctions, reduces local rhythmic activity in the spinal cord slice and disrupts autonomic control in the working heart-brainstem preparation. The role that these gap junctions may play in health and disease in adult animals remains to be elucidated fully. Presympathetic interneurones are located in laminae V, VII and X and the intermediolateral cell column; those in lamina X are GABAergic and directly inhibit SPNs. The GABAergic inputs onto SPNs exert their effects through activation of synaptic and extrasynaptic receptors, which stabilize the membrane at negative potentials. The GABAergic interneurones contribute to rhythmic patterns of activity that can be generated in the spinal cord, because bicuculline reduces network oscillatory activity. These studies indicate that local spinal cord circuitry is critical in enabling appropriate levels and patterning of activity in sympathetic outflow. We need to understand how these circuits may be harnessed in the situation of spinal cord injury.
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Affiliation(s)
- Susan A Deuchars
- School of Biomedical Sciences, University of Leeds, Leeds, LS2 9JT, UK
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Acevedo J, Santana-Almansa A, Matos-Vergara N, Marrero-Cordero LR, Cabezas-Bou E, Díaz-Ríos M. Caffeine stimulates locomotor activity in the mammalian spinal cord via adenosine A1 receptor-dopamine D1 receptor interaction and PKA-dependent mechanisms. Neuropharmacology 2015; 101:490-505. [PMID: 26493631 DOI: 10.1016/j.neuropharm.2015.10.020] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 09/16/2015] [Accepted: 10/15/2015] [Indexed: 01/31/2023]
Abstract
Caffeine is a potent psychostimulant that can have significant and widely variable effects on the activity of multiple neuronal pathways. The most pronounced caffeine-induced behavioral effect seen in rodents is to increase locomotor activity which has been linked to a dose-dependent inhibition of A1 and A(2A) receptors. The effects of caffeine at the level of the lumbar spinal central pattern generator (CPG) network for hindlimb locomotion are lacking. We assessed the effects of caffeine to the locomotor function of the spinal CPG network via extracellular ventral root recordings using the isolated neonatal mouse spinal cord preparation. Addition of caffeine and of an A1 receptor antagonist significantly decreased the cycle period accelerating the ongoing locomotor rhythm, while decreasing burst duration reversibly in most preparations suggesting the role of A1 receptors as the primary target of caffeine. Caffeine and an A1 receptor antagonist failed to stimulate ongoing locomotor activity in the absence of dopamine or in the presence of a D1 receptor antagonist supporting A1/D1 receptor-dependent mechanism of action. The use of caffeine or an A1 receptor blocker failed to stimulate an ongoing locomotor rhythm in the presence of a blocker of the cAMP-dependent protein kinase (PKA) supporting the need of this intracellular pathway for the modulatory effects of caffeine to occur. These results support a stimulant effect of caffeine on the lumbar spinal network controlling hindlimb locomotion through the inhibition of A1 receptors and subsequent activation of D1 receptors via a PKA-dependent intracellular mechanism.
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Affiliation(s)
- JeanMarie Acevedo
- Department of Anatomy and Neurobiology and Institute of Neurobiology, University of Puerto Rico, Medical Sciences Campus, San Juan, PR 00936, USA
| | - Alexandra Santana-Almansa
- Department of Anatomy and Neurobiology and Institute of Neurobiology, University of Puerto Rico, Medical Sciences Campus, San Juan, PR 00936, USA
| | - Nikol Matos-Vergara
- Department of Anatomy and Neurobiology and Institute of Neurobiology, University of Puerto Rico, Medical Sciences Campus, San Juan, PR 00936, USA
| | - Luis René Marrero-Cordero
- Department of Anatomy and Neurobiology and Institute of Neurobiology, University of Puerto Rico, Medical Sciences Campus, San Juan, PR 00936, USA
| | - Ernesto Cabezas-Bou
- Department of Anatomy and Neurobiology and Institute of Neurobiology, University of Puerto Rico, Medical Sciences Campus, San Juan, PR 00936, USA
| | - Manuel Díaz-Ríos
- Department of Anatomy and Neurobiology and Institute of Neurobiology, University of Puerto Rico, Medical Sciences Campus, San Juan, PR 00936, USA.
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Witts EC, Nascimento F, Miles GB. Adenosine-mediated modulation of ventral horn interneurons and spinal motoneurons in neonatal mice. J Neurophysiol 2015; 114:2305-15. [PMID: 26311185 PMCID: PMC4609759 DOI: 10.1152/jn.00574.2014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 08/21/2015] [Indexed: 01/20/2023] Open
Abstract
Neuromodulation allows neural networks to adapt to varying environmental and biomechanical demands. Purinergic signaling is known to be an important modulatory system in many parts of the CNS, including motor control circuitry. We have recently shown that adenosine modulates the output of mammalian spinal locomotor control circuitry (Witts EC, Panetta KM, Miles GB. J Neurophysiol 107: 1925–1934, 2012). Here we investigated the cellular mechanisms underlying this adenosine-mediated modulation. Whole cell patch-clamp recordings were performed on ventral horn interneurons and motoneurons within in vitro mouse spinal cord slice preparations. We found that adenosine hyperpolarized interneurons and reduced the frequency and amplitude of synaptic inputs to interneurons. Both effects were blocked by the A1-type adenosine receptor antagonist DPCPX. Analysis of miniature postsynaptic currents recorded from interneurons revealed that adenosine reduced their frequency but not amplitude, suggesting that adenosine acts on presynaptic receptors to modulate synaptic transmission. In contrast to interneurons, recordings from motoneurons revealed an adenosine-mediated depolarization. The frequency and amplitude of synaptic inputs to motoneurons were again reduced by adenosine, but we saw no effect on miniature postsynaptic currents. Again these effects on motoneurons were blocked by DPCPX. Taken together, these results demonstrate differential effects of adenosine, acting via A1 receptors, in the mouse spinal cord. Adenosine has a general inhibitory action on ventral horn interneurons while potentially maintaining motoneuron excitability. This may allow for adaptation of the locomotor pattern generated by interneuronal networks while helping to ensure the maintenance of overall motor output.
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Affiliation(s)
- Emily C Witts
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife, United Kingdom
| | - Filipe Nascimento
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife, United Kingdom
| | - Gareth B Miles
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife, United Kingdom
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Acton D, Miles GB. Stimulation of Glia Reveals Modulation of Mammalian Spinal Motor Networks by Adenosine. PLoS One 2015; 10:e0134488. [PMID: 26252389 PMCID: PMC4529192 DOI: 10.1371/journal.pone.0134488] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2015] [Accepted: 07/09/2015] [Indexed: 01/05/2023] Open
Abstract
Despite considerable evidence that glia can release modulators to influence the excitability of neighbouring neurons, the importance of gliotransmission for the operation of neural networks and in shaping behaviour remains controversial. Here we characterise the contribution of glia to the modulation of the mammalian spinal central pattern generator for locomotion, the output of which is directly relatable to a defined behaviour. Glia were stimulated by specific activation of protease-activated receptor-1 (PAR1), an endogenous G-protein coupled receptor preferentially expressed by spinal glia during ongoing activity of the spinal central pattern generator for locomotion. Selective activation of PAR1 by the agonist TFLLR resulted in a reversible reduction in the frequency of locomotor-related bursting recorded from ventral roots of spinal cord preparations isolated from neonatal mice. In the presence of the gliotoxins methionine sulfoximine or fluoroacetate, TFLLR had no effect, confirming the specificity of PAR1 activation to glia. The modulation of burst frequency upon PAR1 activation was blocked by the non-selective adenosine-receptor antagonist theophylline and by the A1-receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine, but not by the A2A-receptor antagonist SCH5826, indicating production of extracellular adenosine upon glial stimulation, followed by A1-receptor mediated inhibition of neuronal activity. Modulation of network output following glial stimulation was also blocked by the ectonucleotidase inhibitor ARL67156, indicating glial release of ATP and its subsequent degradation to adenosine rather than direct release of adenosine. Glial stimulation had no effect on rhythmic activity recorded following blockade of inhibitory transmission, suggesting that glial cell-derived adenosine acts via inhibitory circuit components to modulate locomotor-related output. Finally, the modulation of network output by endogenous adenosine was found to scale with the frequency of network activity, implying activity-dependent release of adenosine. Together, these data indicate that glia play an active role in the modulation of mammalian locomotor networks, providing negative feedback control that may stabilise network activity.
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Affiliation(s)
- David Acton
- School of Psychology and Neuroscience, University of St Andrews, Fife, United Kingdom
| | - Gareth B. Miles
- School of Psychology and Neuroscience, University of St Andrews, Fife, United Kingdom
- * E-mail:
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17
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Imlach WL, Bhola RF, May LT, Christopoulos A, Christie MJ. A Positive Allosteric Modulator of the Adenosine A1 Receptor Selectively Inhibits Primary Afferent Synaptic Transmission in a Neuropathic Pain Model. Mol Pharmacol 2015; 88:460-8. [DOI: 10.1124/mol.115.099499] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 06/23/2015] [Indexed: 11/22/2022] Open
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Central or peripheral delivery of an adenosine A1 receptor agonist improves mechanical allodynia in a mouse model of painful diabetic neuropathy. Neuroscience 2014; 285:312-23. [PMID: 25451280 DOI: 10.1016/j.neuroscience.2014.10.065] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 10/28/2014] [Accepted: 10/31/2014] [Indexed: 02/07/2023]
Abstract
Diabetic peripheral neuropathy is a common complication of diabetes mellitus, and a significant proportion of individuals suffer debilitating pain that significantly affects their quality of life. Unfortunately, symptomatic treatment options have limited efficacy, and often carry significant risk of systemic adverse effects. Activation of the adenosine A1 receptor (A1R) by the analgesic small molecule adenosine has been shown to have antinociceptive benefits in models of inflammatory and neuropathic pain. The current study used a mouse model of painful diabetic neuropathy to determine the effect of diabetes on endogenous adenosine production, and if central or peripheral delivery of adenosine receptor agonists could alleviate signs of mechanical allodynia in diabetic mice. Diabetes was induced using streptozocin in male A/J mice. Mechanical withdrawal thresholds were measured weekly to characterize neuropathy phenotype. Hydrolysis of AMP into adenosine by ectonucleotidases was determined in the dorsal root ganglia (DRG) and spinal cord at 8 weeks post-induction of diabetes. AMP, adenosine and the specific A1R agonist, N(6)-cyclopentyladenosine (CPA), were administered both centrally (intrathecal) and peripherally (intraplantar) to determine the effect of activation of adenosine receptors on mechanical allodynia in diabetic mice. Eight weeks post-induction, diabetic mice displayed significantly decreased hydrolysis of extracellular AMP in the DRG; at this same time, diabetic mice displayed significantly decreased mechanical withdrawal thresholds compared to nondiabetic controls. Central delivery AMP, adenosine and CPA significantly improved mechanical withdrawal thresholds in diabetic mice. Surprisingly, peripheral delivery of CPA also improved mechanical allodynia in diabetic mice. This study provides new evidence that diabetes significantly affects endogenous AMP hydrolysis, suggesting that altered adenosine production could contribute to the development of painful diabetic neuropathy. Moreover, central and peripheral activation of A1R significantly improved mechanical sensitivity, warranting further investigation into this important antinociceptive pathway as a novel therapeutic option for the treatment of painful diabetic neuropathy.
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Yamaguchi D, Terayama R, Omura S, Tsuchiya H, Sato T, Ichikawa H, Sugimoto T. Effect of adenosine A1 receptor agonist on the enhanced excitability of spinal dorsal horn neurons after peripheral nerve injury. Int J Neurosci 2013; 124:213-22. [DOI: 10.3109/00207454.2013.842566] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Witts EC, Panetta KM, Miles GB. Glial-derived adenosine modulates spinal motor networks in mice. J Neurophysiol 2011; 107:1925-34. [PMID: 22205649 PMCID: PMC3331664 DOI: 10.1152/jn.00513.2011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The activation of purinergic receptors modulates central pattern generators controlling rhythmic motor behaviors, including respiration in rodents and swimming in frog tadpoles. The present study aimed to determine whether purinergic signaling also modulates the mammalian locomotor central pattern generator. This was investigated by using isolated spinal cord preparations obtained from neonatal mice in which locomotor-related activity can be induced pharmacologically. The application of either ATP or adenosine led to a reduction in the frequency of locomotor activity recorded from ventral roots. ATP had no effect when applied in the presence of both the adenosine receptor antagonist theophylline and the ectonucleotidase inhibitor ARL67156, demonstrating that the effects of ATP application result from the breakdown of ATP to adenosine and subsequent activation of adenosine receptors. The application of theophylline or the A(1)-specific antagonist cyclopentyl dipropylxanthine, but not the A(2A)-receptor antagonist SCH58261, caused an increase in locomotor burst frequency, demonstrating that endogenously derived adenosine activates A(1) receptors during locomotor network activity. Furthermore, theophylline had no effect in the presence of the ectonucleotidase inhibitor ARL67156 or the glial toxins methionine sulfoximine or ethyl fluoracetate, suggesting that endogenous adenosine is derived from ATP, which is released from glia. Finally, adenosine had no effect on slow rhythmic activity recorded upon blockade of all inhibitory transmission, suggesting that adenosine may act via the modulation of inhibitory transmission. Together, these data highlight endogenous purinergic gliotransmission, involving activation of A(1) receptors, as an important intrinsic modulatory system controlling the frequency of activity generated by spinal locomotor circuitry in mammals.
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Affiliation(s)
- Emily C Witts
- School of Biology, Bute Bldg., Univ. of St. Andrews, St. Andrews, Fife KY16 9TS, UK.
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Cieślak M, Kukulski F, Komoszyński M. Emerging role of extracellular nucleotides and adenosine in multiple sclerosis. Purinergic Signal 2011; 7:393-402. [PMID: 21792574 PMCID: PMC3224637 DOI: 10.1007/s11302-011-9250-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 07/11/2011] [Indexed: 12/12/2022] Open
Abstract
Extracellular nucleotides and adenosine play important roles in inflammation. These signaling molecules interact with the cell-surface-located P2 and P1 receptors, respectively, that are widely distributed in the central nervous system and generally exert opposite effects on immune responses. Indeed, extracellular ATP, ADP, UTP, and UDP serve as alarmins or damage-associated molecular patterns that activate mainly proinflammatory mechanisms, whereas adenosine has potent anti-inflammatory and immunosuppressive effects. This review discusses the actual and potential role of extracellular nucleotides and adenosine in multiple sclerosis (MS).
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Affiliation(s)
- Marek Cieślak
- Department of Neurology, WSZ Hospital, 53/59 St. Joseph Street, Toruń, 87-100, Poland,
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22
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Gong QJ, Li YY, Xin WJ, Wei XH, Cui Y, Wang J, Liu Y, Liu CC, Li YY, Liu XG. Differential effects of adenosine A1 receptor on pain-related behavior in normal and nerve-injured rats. Brain Res 2010; 1361:23-30. [PMID: 20850420 DOI: 10.1016/j.brainres.2010.09.034] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 09/08/2010] [Accepted: 09/08/2010] [Indexed: 11/16/2022]
Abstract
This study investigated the effects of N6-cyclopentyladenosine (CPA), a potent and selective adenosine A1 receptor (A1R) agonist in normal and nerve-injured rats and mechanisms of its action by behavioral tests and electrophysiological technique. The results showed: (1) In normal rats, intraperitoneal administration of CPA (1mg/kg) increased paw withdrawal latencies, in a way blocked by a selective A1R antagonist 8-cyclopentyl-1, 3-dipropylxanthine (DPCPX, 3mg/kg, i.p.), but had no influence on the threshold of mechanical stimulation. (2) In rats with neuropathic pain induced by spinal nerve ligation (SNL), CPA reduced thermal hyperalgesia and mechanical allodynia, which could last 6h and 10h, respectively (n=6/group, P<0.05). Both of the effects could be blocked by pretreatment of DPCPX intraperitoneally. (3) The baseline of C-fiber but not A-fiber evoked field potentials was depressed by spinal application of CPA (0.01 mM), and this effect was prevented by application of DPCPX (0.02 mM) 30 min before CPA. (4) Spinal application of CPA depressed long-term potentiation (LTP) of A- and C-fiber evoked field potentials, and both the depression could be blocked by pretreatment of DPCPX 30 min before CPA. These results suggested that the activation of A1R has different influences on normal and neuropathic rats probably due to the absence and presence of central sensitization in spinal dorsal horn.
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Affiliation(s)
- Qing-Juan Gong
- Department of Physiology and Pain Research Center, Zhongshan Medical School, Sun Yat-Sen University, 74 Zhongshan Rd 2, Guangzhou 510080, China
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Li L, Hao JX, Fredholm BB, Schulte G, Wiesenfeld-Hallin Z, Xu XJ. Peripheral adenosine A2A receptors are involved in carrageenan-induced mechanical hyperalgesia in mice. Neuroscience 2010; 170:923-8. [PMID: 20678550 DOI: 10.1016/j.neuroscience.2010.07.045] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Revised: 07/19/2010] [Accepted: 07/22/2010] [Indexed: 02/07/2023]
Abstract
Here we studied the role of peripheral adenosine A(2A) receptors in mechanical hyperalgesia during inflammation using mice lacking the A(2A) receptors. Unilateral s.c. administration of the local inflammatory agent λ-carrageenan induced profound mechanical hyperalgesia 24 h after administration in the ipsilateral hind paw in wild-type mice. In homozygous mice lacking the A(2A) receptors, carrageenan-induced hyperalgesia was significantly reduced compared to wild type controls. The reduction in inflammatory hyperalgesia seen in A(2A) receptor knock-out mice was not associated with changes in paw edema. CGS 21680, a selective A(2A) receptor agonist, produced significantly more mechanical hyperalgesia in wild type females than in wild type males upon direct s.c. injection into the hindpaw whereas it had no effect upon systemic administration. The hyperalgesic effect of CGS 21680 was markedly reduced in the A(2A) knock-out mice of both sexes. Subcutaneous ZM-241,385, a selective A(2A) receptor antagonist, injected into the hindpaw reduced the mechanical hyperalgesia following carrageenan in female mice, but not in males. The results indicate that activation of peripheral adenosine A(2A) receptors during inflammation is associated with mechanical hyperalgesia, and that this effect is more prominent in females than in males.
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Affiliation(s)
- L Li
- Department of Physiology and Pharmacology, Karolinska Institutet, Nanna Svartz Väg 2, S-171 77 Stockholm, Sweden.
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Pape JR, Bertrand SS, Lafon P, Odessa MF, Chaigniau M, Stiles JK, Garret M. Expression of GABA(A) receptor alpha3-, theta-, and epsilon-subunit mRNAs during rat CNS development and immunolocalization of the epsilon subunit in developing postnatal spinal cord. Neuroscience 2009; 160:85-96. [PMID: 19249336 DOI: 10.1016/j.neuroscience.2009.02.043] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Revised: 02/03/2009] [Accepted: 02/19/2009] [Indexed: 12/13/2022]
Abstract
Ionotropic GABA(A) receptors are heteromeric structures composed of a combination of five from at least 16 different subunits. Subunit genes are expressed in distinct cell types at specific times during development. The most abundant native GABA(A) receptors consist of alpha1-, beta2-, and gamma2-subunits that are co-expressed in numerous brain areas. alpha3-, theta-, And epsilon-subunits are clustered on the X chromosome and show striking overlapping expression patterns throughout the adult rat brain. To establish whether these subunits are temporally and spatially co-expressed, we used in situ hybridization to analyze their expression throughout rat development from embryonic stage E14 to postnatal stage P12. Each transcript exhibited a unique or a shared regional and temporal developmental expression profile. The thalamic expression pattern evolved from a restricted expression of epsilon and theta transcripts before birth, to a theta and alpha3 expression at birth, and finally to a grouped epsilon, theta and alpha3 expression postpartum. However, strong similarities occurred, such as a grouped expression of the three subunits within the hypothalamus, tegmentum and pontine nuclei throughout the developmental process. At early stages of development (E17), epsilon and theta appeared to have a greater spatial distribution before the dominance of the alpha3 subunit transcript around birth. We also revealed expression of alpha3, theta, and epsilon in the developing spinal cord and identified neurons that express epsilon in the postnatal dorsal horn, intermediolateral column and motoneurons. Our findings suggest that various combinations of alpha3-, theta- and epsilon-subunits may be assembled at a regional and developmental level in the brain.
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Affiliation(s)
- J-R Pape
- Université de Bordeaux, CNRS, UMR 5228, France
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Adenosine modulates excitatory synaptic transmission and suppresses neuronal death induced by ischaemia in rat spinal motoneurones. Pflugers Arch 2008; 457:441-51. [PMID: 18584206 DOI: 10.1007/s00424-008-0542-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Accepted: 06/04/2008] [Indexed: 10/21/2022]
Abstract
Although adenosine is an important neuromodulator, its role in modulating motor functions at the level of the spinal cord is poorly understood. In the present study, we investigated the effects of adenosine on excitatory synaptic transmission and neuronal death induced by experimental ischaemia by using whole-cell patch-clamp recordings from lamina IX neurones in spinal cord slices. Adenosine significantly decreased the frequency of miniature excitatory postsynaptic currents (mEPSCs) in almost all neurones examined that could be mimicked by an A(1) receptor agonist, N (6)-cyclopentyladenosine (CPA), and inhibited by an A(1) receptor antagonist, 8-cyclopentyl-1, 3-dipropylxanthine (DPCPX). Interestingly, adenosine increased mEPSC frequency in the presence of DPCPX in a subpopulation of neurones. In these neurones, an A(2A) receptor agonist, 2-[4-(2-carbonylethyl)-phenethylamino]-5'-N-ethylcarboxamidoadenosine (CGS21680), increased mEPSC frequency. Adenosine also induced an outward current that was blocked by the addition of Cs(+) and tetraethylammonium into the patch-pipette solution and inhibited in the presence of Ba(2+). The adenosine-induced outward current was mimicked by CPA, but not CGS21680, and inhibited by DPCPX. Moreover, superfusing with ischaemia simulating medium (ISM) generated an agonal inward current in all of the neurones tested. The latencies of the inward currents induced by ISM were significantly prolonged by adenosine or CPA, but not by CGS21680. These results suggest that adenosine receptors are functionally expressed in both the pre- and postsynaptic sites of lamina IX neurones and that their activation may exert multiple effects on motor function. Moreover, this study has provided a cellular basis for an involvement of A(1) receptors in the neuroprotective actions of adenosine.
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Poole SL, Lewis DI, Deuchars SA. Histamine depolarizes neurons in the dorsal vagal complex. Neurosci Lett 2007; 432:19-24. [PMID: 18162318 DOI: 10.1016/j.neulet.2007.11.055] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2007] [Revised: 11/20/2007] [Accepted: 11/29/2007] [Indexed: 11/17/2022]
Abstract
We sought to determine whether histamine has effects on single neurons in the dorsal vagal complex of the brainstem since previous studies have suggested a role for histamine receptors in this region. Using whole-cell patch clamp recordings from neurons within the nucleus of the tractus solitarius (NTS) and the dorsal vagal nucleus (DVN), histamine (20 microM) depolarized a small proportion of neurons in these regions accompanied by a decrease in input resistance. Although few neurons were depolarized (21% of NTS neurons and 15% of DVN neurons), those that were affected showed robust depolarizations of 13 mV. These depolarizations were antagonized by the histamine H1 receptor antagonist triprolidine (2 microM) and were subject to a level of desensitization. Neither histamine nor the H3 receptor agonist imetit caused any change in the amplitudes of excitatory or inhibitory postsynaptic potentials elicited in NTS neurons by stimulation of the solitary tract. These data indicate that histamine has a restricted but profound effect on neurons in the dorsal vagal complex.
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Affiliation(s)
- Sarah L Poole
- Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
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Poole SL, Deuchars J, Lewis DI, Deuchars SA. Subdivision-specific responses of neurons in the nucleus of the tractus solitarius to activation of mu-opioid receptors in the rat. J Neurophysiol 2007; 98:3060-71. [PMID: 17898143 DOI: 10.1152/jn.00755.2007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Microinjection of opioid receptor agonists into the nucleus tractus solitarius (NTS) has differential effects on cardiovascular, respiratory, and gastrointestinal responses. This can be achieved either by presynaptic modulation of inputs onto neurons or by postsynaptic activation of receptors on neurons in specific regions. Therefore we sought to determine whether responses of neurons to activation of opioid receptors were dependent on their location within the NTS. Using whole cell patch-clamp recordings from neurons within the NTS, the mu opioid receptor (MOR) agonist [D-Ala(2), N-Me-Phe(4),Gly(5)-ol]-enkephalin (DAMGO, 100 nM) hyperpolarized a proportion of neurons in the medial, dorsomedial and dorsolateral NTS, whereas no postsynaptic responses were observed in remaining subdivisions. DAMGO reduced the amplitude of solitary tract-evoked excitatory postsynaptic potentials (EPSPs) in all neurons tested, regardless of subdivision. The kappa opioid receptor (KOR) agonist U69593 (10-20 microM) also hyperpolarized a small fraction of neurons (6/79) and decreased the amplitude of EPSPs in 50% of neurons. In contrast, the delta-opioid receptor agonist DPDPE (1-4 microM) had no presynaptic or postsynaptic effects on NTS neurons even after preincubation with bradykinin. Anatomical data at the light and electron microscopic level complemented electrophysiological observations with respect to MOR location and further showed that MORs were present at both presynaptic and postsynaptic sites in the dorsolateral NTS, often at the same synapse. These data demonstrate site specific responses of neurons to activation of MORs and KORs, which may underlie their ability to modulate different autonomic reflexes.
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MESH Headings
- Analgesics, Opioid/pharmacology
- Animals
- Animals, Newborn
- Drug Interactions
- Electric Stimulation/methods
- Excitatory Postsynaptic Potentials/drug effects
- Excitatory Postsynaptic Potentials/physiology
- Excitatory Postsynaptic Potentials/radiation effects
- In Vitro Techniques
- Male
- Microscopy, Immunoelectron/methods
- Neurons/physiology
- Neurons/ultrastructure
- Patch-Clamp Techniques/methods
- Rats
- Rats, Wistar
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, Opioid, mu/metabolism
- Receptors, Opioid, mu/ultrastructure
- Solitary Nucleus/cytology
- Somatostatin/analogs & derivatives
- Somatostatin/pharmacology
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Affiliation(s)
- Sarah L Poole
- Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
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28
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Selden NR, Carlson JD, Cetas J, Close LN, Heinricher MM. Purinergic actions on neurons that modulate nociception in the rostral ventromedial medulla. Neuroscience 2007; 146:1808-16. [PMID: 17481825 DOI: 10.1016/j.neuroscience.2007.03.044] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2007] [Revised: 03/22/2007] [Accepted: 03/24/2007] [Indexed: 01/20/2023]
Abstract
The rostral ventromedial medulla (RVM) serves as a critical link in bulbo-spinal nociceptive modulation. Within the RVM, 'off-cells' pause and 'on-cells' discharge immediately prior to a nocifensive reflex. These neurons are also activated and inactivated, respectively, by local or systemic application of opioids. Off-cell activation leads to behavioral anti-nociception and on-cell activation to hyperalgesia. Thus, on- and off-cell populations allow bi-directional modulation of nociception by the RVM. A third neuronal population, neutral cells, shows no reflex-related change in discharge. The role of neutral cells in nociception, if any, is unknown. We investigated the responses of on-, off- and neutral cells to the iontophoretic application of purinergic ligands in lightly anesthetized rats. On-cell firing increased rapidly in response to application of ATP and to the P2X-receptor agonist, alpha,beta-methylene ATP. Off-cell firing increased gradually in response to ATP and to the P2Y-receptor agonist, 2-methylthio-ATP. All of these responses were attenuated or reversed by the non-specific P2-receptor antagonists, suramin and pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS). Activation of off-cells was preferentially antagonized by the relatively selective P2Y antagonist, MRS2179. By contrast with activation of on- and off-cells by ATP, neutral cell firing was depressed by ATP, adenosine and the P1-receptor agonist, 5'-(N-ethylcarboxamido) adenosine (NECA). Neutral cell responses to these agonists were at least partially reversed by the adenosine-receptor antagonist, 8-phenyltheophylline (8PT). These data imply that on-cells preferentially express P2X-receptors, off-cells P2Y-receptors and neutral cells P1-receptors. Immunohistochemical localization of purinergic receptors confirms the presence of some subtypes of P2X, P2Y and A1 receptors on neuronal cell bodies and fibers within the RVM. The differential responses of on-, off- and neutral-cells to purinergic ligands highlight the value of pharmacological signatures in further delineation of the anatomy, connectivity and function of this therapeutically important system.
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Affiliation(s)
- N R Selden
- Department of Neurological Surgery, Oregon Health & Science University, Mail code CH8N, 3303 Southwest Bond Avenue, Portland, OR 97239, USA.
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29
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Deuchars SA. Multi-tasking in the spinal cord--do 'sympathetic' interneurones work harder than we give them credit for? J Physiol 2007; 580:723-9. [PMID: 17347266 PMCID: PMC2075457 DOI: 10.1113/jphysiol.2007.129429] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The role of interneurones in the control of sympathetic activity has been somewhat of a mystery since, for many years, it was difficult to target these cells for study. Recently scientists have started to unravel the action potential properties of these neurones, where they receive their inputs from and where they project to. This review looks at the information known to date about sympathetic interneurones. The locations of these neurones and their local axonal ramifications suggest that they play a more widespread function than previously thought. Therefore the data to support such a theory are also examined.
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Affiliation(s)
- Susan A Deuchars
- Institute of Membrane and Systems Biology, University of Leeds, Leeds, West Yorkshire, LS2 9JT, UK.
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30
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King AE, Ackley MA, Cass CE, Young JD, Baldwin SA. Nucleoside transporters: from scavengers to novel therapeutic targets. Trends Pharmacol Sci 2006; 27:416-25. [PMID: 16820221 DOI: 10.1016/j.tips.2006.06.004] [Citation(s) in RCA: 204] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2006] [Revised: 04/18/2006] [Accepted: 06/19/2006] [Indexed: 11/26/2022]
Abstract
Hydrophilic purine and pyrimidine nucleosides rely on specialized carrier proteins for their membrane translocation. The recent identification of two gene families encoding equilibrative and concentrative nucleoside transporters in mammals and other organisms has provided the essential breakthrough to a more complete understanding of the biological significance of nucleoside transport. Although nucleoside salvage is a primary function of these proteins, recent data indicate functions beyond metabolic recycling. In brain and spinal cord, for example, nucleoside transporters have the potential to regulate synaptic levels of neuroactive purines such as adenosine and, thereby, indirectly modulate physiological processes through G-protein-coupled purine P1 receptors. As described in this review, recent research indicates novel putative functions for CNS nucleoside transporters in sleep, arousal, drug and alcohol addiction, nociception and analgesia. The therapeutic use of nucleoside analogue drugs and nucleoside transporter inhibitors in viral, neoplastic, cardiovascular and infectious disease is also described.
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Affiliation(s)
- Anne E King
- Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
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31
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Governo RJM, Deuchars J, Baldwin SA, King AE. Localization of the NBMPR-sensitive equilibrative nucleoside transporter, ENT1, in the rat dorsal root ganglion and lumbar spinal cord. Brain Res 2005; 1059:129-38. [PMID: 16226730 DOI: 10.1016/j.brainres.2005.08.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2005] [Revised: 08/05/2005] [Accepted: 08/08/2005] [Indexed: 10/25/2022]
Abstract
ENT1 is an equilibrative nucleoside transporter that enables trans-membrane bi-directional diffusion of biologically active purines such as adenosine. In spinal cord dorsal horn and in sensory afferent neurons, adenosine acts as a neuromodulator with complex pro- and anti-nociceptive actions. Although uptake and release mechanisms for adenosine are believed to exist in both the dorsal horn and sensory afferent neurons, the expression profile of specific nucleoside transporter subtypes such as ENT1 is not established. In this study, immunoblot analysis with specific ENT1 antibodies (anti-rENT1(227-290) or anti-hENT1(227-290)) was used to reveal the expression of ENT1 protein in tissue homogenates of either adult rat dorsal horn or dorsal root ganglia (DRG). Immunoperoxidase labeling with ENT1 antibodies produced specific staining in dorsal horn which was concentrated over superficial laminae, especially the substantia gelatinosa (lamina II). Immunofluorescence double-labeling revealed a punctate pattern for ENT1 closely associated, in some instances, with cell bodies of either neurons (confirmed with NeuN) or glia (confirmed with CNPase). Electron microscopy analysis of ENT1 expression in lamina II indicated its presence within pre- and post-synaptic elements, although a number of other structures, including myelinated and unmyelinated, axons were also labeled. In sensory ganglia, ENT1 was localized to a high proportion of cell bodies of all sizes that co-expressed substance P, IB4 or NF, although ENT1 was most highly expressed in the peptidergic population. These data provide the first detailed account of the expression and cellular distribution of ENT1 in rat dorsal horn and sensory ganglia. The functional significance of ENT1 expression with regard to the homeostatic regulation of adenosine at synapses remains to be established.
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32
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Wu WP, Hao JX, Halldner L, Lövdahl C, DeLander GE, Wiesenfeld-Hallin Z, Fredholm BB, Xu XJ. Increased nociceptive response in mice lacking the adenosine A1 receptor. Pain 2005; 113:395-404. [PMID: 15661449 DOI: 10.1016/j.pain.2004.11.020] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2004] [Revised: 11/05/2004] [Accepted: 11/22/2004] [Indexed: 11/28/2022]
Abstract
The role of the adenosine A1 receptor in nociception was assessed using mice lacking the A1 receptor (A1R-/-) and in rats. Under normal conditions, the A1R-/- mice exhibited moderate heat hyperalgesia in comparison to the wild-type mice (A1R+/+). The mechanical and cold sensitivity were unchanged. The antinociceptive effect of morphine given intrathecally (i.t.), but not systemically, was reduced in A1R-/- mice and this reduction in the spinal effect of morphine was not associated with a decrease in binding of the mu-opioid ligand DAMGO in the spinal cord. A1R-/- mice also exhibited hypersensitivity to heat, but not mechanical stimuli, after localized inflammation induced by carrageenan. In mice with photochemically induced partial sciatic nerve injury, the neuropathic pain-like behavioral response to heat or cold stimulation were significantly increased in the A1R-/-mice. Peripheral nerve injury did not change the level of adenosine A1 receptor in the dorsal spinal cord in rats and i.t. administration of R-PIA effectively alleviated pain-like behaviors after partial nerve injury in rats and in C57/BL/6 mice. Taken together, these data suggest that the adenosine A1 receptor plays a physiological role in inhibiting nociceptive input at the spinal level in mice. The C-fiber input mediating noxious heat is inhibited more than other inputs. A1 receptors also contribute to the antinociceptive effect of spinal morphine. Selective A1 receptor agonists may be tested clinically as analgesics, particularly under conditions of neuropathic pain.
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Affiliation(s)
- Wei-Ping Wu
- Department of Neurotec, Division of Clinical Neurophysiology, Karolinska Institutet, Karolinska University Hospital-Huddinge, S-141 86 Stockholm, Sweden Department of Physiology and Pharmacology, Section of Molecular Neuropharmacology, Karolinska Institutet, S-141 86 Stockholm, Sweden Department of Pharmacology, College of Pharmacy, Oregon State University, Corvallis, OR 97311-3507, USA
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33
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Avsar E, Empson RM. Adenosine acting via A1 receptors, controls the transition to status epilepticus-like behaviour in an in vitro model of epilepsy. Neuropharmacology 2004; 47:427-37. [PMID: 15275832 DOI: 10.1016/j.neuropharm.2004.04.015] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2003] [Revised: 04/27/2004] [Accepted: 04/29/2004] [Indexed: 11/16/2022]
Abstract
Adenosine has powerful inhibitory effects in the central nervous system. In this study, we aim to understand how adenosine controls the progression of seizure-like events (SLEs) in a seizure-prone region of the brain, the entorhinal cortex. We chose to use a low Mg(2+) model of epilepsy in an in vitro slice preparation where, in the entorhinal cortex, SLEs progress into a type of epileptiform activity called late recurrent discharges (LRDs) that bear resemblance to status epilepticus. Adenosine, acting via its A1 receptor, exerted powerful inhibitory effects to prevent the spontaneous progression to LRDs while the potent A1 receptor antagonist, DPCPX, accelerated the progression in a concentration dependent manner. The spontaneous progression from SLEs to LRDs was associated with a decline in total cellular ATP levels and studies with metabolic inhibitors indicated a key role for the production of endogenous adenosine from ATP. We therefore hypothesise that when ATP becomes rate limiting, extracellular adenosine levels fall, the normal inhibitory brake is removed and the progression from SLEs to LRDs or status epilepticus-like activity can ensue. Moreover, under these conditions, inhibition of the adenine nucleotide salvage pathways reversed the status epilepticus-like activity. Our findings suggest a powerful role for adenosine for the control of the progression to status epilepticus-like activity in an epilepsy model that is refractory to most anti-epileptic drugs. On this basis, manipulation of adenine nucleotide metabolism may represent a potential therapeutic approach for the treatment of status epilepticus.
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Affiliation(s)
- Emin Avsar
- School of Biological Sciences, Royal Holloway, University of London, Egham Hill, Egham Surrey TW20 0EX, UK
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34
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Ramos-Zepeda G, Schröder W, Rosenow S, Herrero JF. Spinal vs. supraspinal antinociceptive activity of the adenosine A1 receptor agonist cyclopentyl-adenosine in rats with inflammation. Eur J Pharmacol 2004; 499:247-56. [PMID: 15381046 DOI: 10.1016/j.ejphar.2004.07.083] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2004] [Revised: 07/12/2004] [Accepted: 07/15/2004] [Indexed: 11/20/2022]
Abstract
The adenosine A(1) receptor is involved in spinal cord antinociception. As its role at supraspinal sites is not well known, we studied the systemic effects of its agonist N-cyclopentyl-adenosine (CPA) in single motor units from adult-spinalized, intact and sham-spinalized rats. CPA was not effective after spinalization, but it was very effective in intact animals (ID50: 92+/-1.3 microg/kg, noxious pinch) and over 10-fold more potent in sham-spinalized animals (ID50 of 8.3+/-1 microg/kg). Wind-up was also inhibited by CPA. We also studied the effect of CPA in the immature spinal cord preparation, where CPA dose-dependently inhibited responses to low (IC50s: 9+/-0.7 and 7.7+/-1.3 nM) and high intensity stimulation (IC50s: 4.9+/-0.5 and 12.1+/-2 nM). We conclude that the integrity of the spinal cord is crucial for the antinociceptive activity of systemic CPA in adult rats but not in immature rats, not yet influenced by a completely developed supraspinal control.
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Affiliation(s)
- Guillermo Ramos-Zepeda
- Departamento de Fisiología, Facultad de Medicina, Universidad de Alcalá, Alcalá de Henares, 28871 Madrid, Spain
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35
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Yang K, Fujita T, Kumamoto E. Adenosine inhibits GABAergic and glycinergic transmission in adult rat substantia gelatinosa neurons. J Neurophysiol 2004; 92:2867-77. [PMID: 15201307 DOI: 10.1152/jn.00291.2004] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The effect of adenosine on inhibitory postsynaptic currents (IPSCs) was examined in substantia gelatinosa (SG) neurons of adult rat spinal cord slices by using the whole cell patch-clamp technique. Adenosine reversibly reduced the amplitude of GABAergic and glycinergic electrically evoked IPSCs (eIPSCs) in a dose-dependent manner (EC50 = 14.5 and 19.1 microM, respectively). The A1 adenosine-receptor agonist N6-cyclopentyladenosine also reduced the eIPSCs, whereas the A1 antagonist 8-cyclopentyl-1,3-dimethylxanthine reversed the inhibition produced by adenosine. In paired-pulse experiments, the ratio of the second to first GABAergic or glycinergic eIPSC amplitude was increased by adenosine, whereas the response of SG neurons to exogenous GABA or glycine was unaffected. Adenosine reduced the frequency of GABAergic and glycinergic spontaneous IPSCs without changing their amplitude. This reduction in frequency disappeared in the presence of a K+ -channel blocker (4-aminopyridine) but not in the absence of Ca2+. The inhibition by adenosine disappeared in the presence of cyclic-AMP analog (8-Br-cyclic AMP) and adenylate-cyclase activator (forskolin) but not protein-kinase C (PKC) activator (phorbol-12,13-dibutyrate). We conclude that adenosine suppresses inhibitory transmission in SG neurons by activating presynaptic A1 receptors and that this action is mediated by K+ channels and cyclic AMP but not by Ca2+ channels and PKC. This inhibitory action of adenosine probably contributes to the modulation of pain transmission in the SG.
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Affiliation(s)
- Kun Yang
- Department of Physiology, Saga Medical School, Saga 849-8501, Japan
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36
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Peng SC, Ho CM, Ho ST, Tsai SK, Su CK. The role of intraspinal adenosine A1 receptors in sympathetic regulation. Eur J Pharmacol 2004; 492:49-55. [PMID: 15145705 DOI: 10.1016/j.ejphar.2004.04.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2003] [Revised: 03/24/2004] [Accepted: 04/01/2004] [Indexed: 11/28/2022]
Abstract
Using a splanchnic nerve-spinal cord preparation in vitro, we have previously demonstrated that tonic sympathetic activity is generated from the thoracic spinal cord. Here, we sought to determine if adenosine receptors play a role in modulating this spinally generated sympathetic activity. Various adenosine analogs were applied. N6-Cyclopentyladenosine (CPA, adenosine A1 receptor agonist) and 5'-N-ethylcarboxamidoadenosine (NECA, adenosine A1/A2 receptor agonist) reduced, while N6-[2-(4-aminophenyl)ethyl]adenosine (APNEA, non-selective adenosine A3 receptor agonist) did not alter sympathetic activity. The inhibitory effect of CPA or NECA on sympathetic activity was reversed by 8-cyclopentyltheophylline (CPT, adenosine A1 receptor antagonist) or abolished by CPT pretreatment. In the presence of 3,7-dimethyl-1-propargylxanthine (DMPX, adenosine A2 receptor antagonist), sympathetic activity was still reduced by CPA or NECA. Sympathetic activities were not changed by applications of the more selective adenosine A2 or A3 receptor agonists or antagonists, including 4-[2-[[6-amino-9-(N-ethyl-beta-D-ribofuranuronamidosyl)-9H-purin-2-yl]amino]ethyl]benzenepropanoic acid (CGS21680), 4-(2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl)phenol (ZM241385), 2-chloro-N6-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (Chloro-IB-MECA), and 3-ethyl-5-benzyl-2-methyl-4-phenylethynyl-6-phenyl-1,4-(+/-)-dihydropyridine-3,5-dicarboxylate (MRS1191). These findings exclude a possible involvement of A2 or A3 receptors in sympathetic regulation at the spinal levels. Interestingly, CPT alone did not affect sympathetic activity, suggesting that adenosine A1 receptors are endogenously quiescent under our experimental conditions. We conclude that intraspinal adenosine A1 receptors may down-regulate sympathetic outflow and serve as a part of the scheme for neuroprotection.
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Affiliation(s)
- Shu-Chun Peng
- Institute of Biomedical Sciences, Academia Sinica, Taiwan
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37
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Zhang JM, Wang HK, Ye CQ, Ge W, Chen Y, Jiang ZL, Wu CP, Poo MM, Duan S. ATP released by astrocytes mediates glutamatergic activity-dependent heterosynaptic suppression. Neuron 2004; 40:971-82. [PMID: 14659095 DOI: 10.1016/s0896-6273(03)00717-7] [Citation(s) in RCA: 477] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Extracellular ATP released from axons is known to assist activity-dependent signaling between neurons and Schwann cells in the peripheral nervous system. Here we report that ATP released from astrocytes as a result of neuronal activity can also modulate central synaptic transmission. In cultures of hippocampal neurons, endogenously released ATP tonically suppresses glutamatergic synapses via presynaptic P2Y receptors, an effect that depends on the presence of cocultured astrocytes. Glutamate release accompanying neuronal activity also activates non-NMDA receptors of nearby astrocytes and triggers ATP release from these cells, which in turn causes homo- and heterosynaptic suppression. In CA1 pyramidal neurons of hippocampal slices, a similar synaptic suppression was also produced by adenosine, an immediate degradation product of ATP released by glial cells. Thus, neuron-glia crosstalk may participate in activity-dependent synaptic modulation.
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Affiliation(s)
- Jing-ming Zhang
- Institute of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031 China
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38
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Kiguchi S, Imamura T, Ichikawa K, Kojima M. Oxcarbazepine antinociception in animals with inflammatory pain or painful diabetic neuropathy. Clin Exp Pharmacol Physiol 2004; 31:57-64. [PMID: 14756685 DOI: 10.1111/j.1440-1681.2004.03950.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
1. Diabetic neuropathy is one of the most frequent complications of diabetes mellitus. However, the mechanisms underlying these disorders are not yet well defined and it has been reported that currently available analgesics have hardly any ameliorating effect on painful diabetic neuropathy. 2. The purpose of the present study was to evaluate the antinociceptive effect of oxcarbazepine (OCBZ), a keto derivative of carbamazepine (CBZ), in animal models generally used in pain research and in rats and mice with streptozotocin (STZ)-induced diabetes. In addition, we compared the effect of OCBZ with those of CBZ, mexiletine and morphine. 3. Diabetes was induced by injection of STZ at a dose of 300 mg/kg (i.p.) in mice and 50 mg/kg (i.v.) in rats. Experiments were conducted 2 weeks after STZ injection and those animals with a serum glucose level above 400 mg/dL were used for data analysis. Antinociceptive effects of the drugs were evaluated by the paw withdrawal test (normal, STZ-induced diabetic and carrageenin-injected rats), tail-flick test (normal and STZ-induced diabetic mice) and nociceptive behaviour (formalin-injected mice). 4. In the present study, diabetic mice showed thermal hyperalgesia and diabetic rats exhibited mechanical hyperalgesia. From these results, the STZ-induced diabetic animals used in the present study were found to be suitable for research on painful diabetic neuropathy. In STZ-induced diabetic animals, the antinociceptive effects of OCBZ, CBZ and mexiletine were facilitated, whereas the effect of morphine was attenuated, compared with effects in normal animals. 5. Oxcarbazepine inhibited the formalin-induced biphasic pain responses and increased the nociceptive threshold in the case of carrageenin-induced hyperalgesia. In view of these results, inhibition of substance P-mediated pain transmission may be involved in the antinociceptive action of OCBZ. 6. These results indicate that OCBZ has an analgesic action and is a possible therapeutic agent for the treatment of neuropathic pain, such as occurs in painful diabetic neuropathy.
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Affiliation(s)
- Sumiyoshi Kiguchi
- Pharmacology Research, R&D, Kissei Pharmaceutical Co. Ltd., 4365-1 Kashiwabara, Hotaka, Minamiazumi, Nagano 399-8304, Japan.
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39
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Lao LJ, Kawasaki Y, Yang K, Fujita T, Kumamoto E. Modulation by adenosine of aδ and c primary-afferent glutamatergic transmission in adult rat substantia gelatinosa neurons. Neuroscience 2004; 125:221-31. [PMID: 15051161 DOI: 10.1016/j.neuroscience.2004.01.029] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/25/2004] [Indexed: 10/26/2022]
Abstract
The present study examined the actions of adenosine on monosynaptic Adelta and C primary-afferent excitatory postsynaptic currents (EPSCs) recorded from substantia gelatinosa (SG) neurons of an adult rat spinal cord slice. In 67% of the neurons examined, adenosine reversibly decreased the amplitude of the Adelta-fiber EPSC, while in 13% of the neurons the amplitude was reduced or unaffected, which was followed by its increase persisting for several minutes after adenosine washout. The remaining neurons did not exhibit a change in the amplitude. The reduction in Adelta-fiber EPSC amplitude by adenosine was dose-dependent with an effective concentration for half-inhibition (EC50) value of 217 microM. When examined by using a paired-pulse stimulus, a ratio of the second to first Adelta-fiber EPSC amplitude under the reduction was larger than that of EPSC amplitude in the control, suggesting a presynaptic action of adenosine. In 69% of the neurons tested, the C-fiber EPSC was reversibly decreased in amplitude by adenosine (100 microM) by an extent comparable to that of Adelta-fiber EPSC; the remaining neurons were without adenosine actions. Similar inhibitory actions of adenosine were also seen in neurons where both Adelta-fiber and C-fiber EPSCs were elicited. Similar reduction in the Adelta-fiber or C-fiber EPSC amplitude was induced by an A1 adenosine-receptor agonist, N6-cyclopentyladenosine (1 microM), and the adenosine-induced reduction was not observed in the presence of an A1 antagonist, 8-cyclopentyl-1,3-dipropylxanthine (1 microM). An A2a agonist, CGS 21680 (1 microM), did not significantly affect the Adelta-fiber EPSC amplitude. It is concluded that adenosine presynaptically inhibits monosynaptic Adelta-fiber and C-fiber transmission by a similar extent through the activation of the A1 receptor in many but not all SG neurons; this could contribute to at least a part of antinociception by intrathecally administered adenosine analogues and probably by endogenous adenosine.
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Affiliation(s)
- L-J Lao
- Department of Physiology, Saga Medical School, 5-1-1 Nabeshima, Saga 849-8501, Japan
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40
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Lynch ME, Clark AJ, Sawynok J. Intravenous adenosine alleviates neuropathic pain: a double blind placebo controlled crossover trial using an enriched enrolment design. Pain 2003; 103:111-7. [PMID: 12749965 DOI: 10.1016/s0304-3959(02)00419-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Adenosine analogs produce analgesic actions in nociceptive paradigms and alleviate manifestations of neuropathic pain in nerve injury models in rodents. In humans, previous work indicates an analgesic effect for adenosine administered intravenously in postoperative and neuropathic pain. In this double blind placebo controlled crossover trial, we used an enriched enrolment design to determine the effects of intravenous adenosine (50 microg/kg/min over 60min) on neuropathic pain. In Phase 1 of the trial, adenosine was administered in an open label manner, while in Phase 2 adenosine was administered in a double blind placebo controlled manner to 23 adenosine responders who had experienced a 30% or greater response in the open trial. Outcome measures included the McGill pain questionnaire (MPQ), which generates a pain rating index (PRI), and contains a visual analog scale (VAS) of pain intensity, the neuropathy pain scale (NPS), and a VAS for pain relief. Subjects also graded the degree of allodynia and hyperalgesia using a VAS. Adenosine led to a significant reduction in spontaneous pain according to the MPQ-PRI, the MPQ-VAS and the VAS for pain relief. The NPS showed a pattern similar to the MPQ-PRI, with statistically significant reductions in scales 1 (intensity), 3 (hot), 6 (sensitive), 7 (itchy) and 9 (unpleasant). Adenosine also led to a significant reduction in pinprick hyperalgesia, but not in allodynia. Three patients from Phase 1 of the trial experienced long term resolution of their pain following intravenous adenosine (5,16,25 months). The results of this study support previous reports that indicate intravenous adenosine alleviates neuropathic pain and hyperalgesia.
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Abstract
In the central nervous system (CNS), adenosine is an important neuromodulator and regulates neuronal and non-neuronal cellular function (e.g. microglia) by actions on extracellular adenosine A(1), A(2A), A(2B) and A(3) receptors. Extracellular levels of adenosine are regulated by synthesis, metabolism, release and uptake of adenosine. Adenosine also regulates pain transmission in the spinal cord and in the periphery, and a number of agents can alter the extracellular availability of adenosine and subsequently modulate pain transmission, particularly by activation of adenosine A(1) receptors. The use of capsaicin (which activates receptors selectively expressed on C-fibre afferent neurons and produces neurotoxic actions in certain paradigms) allows for an interpretation of C-fibre involvement in such processes. In the spinal cord, adenosine availability/release is enhanced by depolarization (K(+), capsaicin, substance P, N-methyl-D-aspartate (NMDA)), by inhibition of metabolism or uptake (inhibitors of adenosine kinase (AK), adenosine deaminase (AD), equilibrative transporters), and by receptor-operated mechanisms (opioids, 5-hydroxytryptamine (5-HT), noradrenaline (NA)). Some of these agents release adenosine via an equilibrative transporter indicating production of adenosine inside the cell (K(+), morphine), while others release nucleotide which is converted extracellularly to adenosine by ecto-5'-nucleotidase (capsaicin, 5-HT). Release can be capsaicin-sensitive, Ca(2+)-dependent and involve G-proteins, and this suggests that within C-fibres, Ca(2+)-dependent intracellular processes regulate production and release of adenosine. In the periphery, adenosine is released from both neuronal and non-neuronal sources. Neuronal release from capsaicin-sensitive afferents is induced by glutamate and by neurogenic inflammation (capsaicin, low concentration of formalin), while that from sympathetic postganglionic neurons (probably as adenosine 5'-triphosphate (ATP) with NA) occurs following more generalized inflammation. Such release is modified differentially by inhibitors of AK and AD. Following nerve injury, there is an alteration in capsaicin-sensitive adenosine release, as spinal release now is less responsive to opioids, while peripheral release is less responsive to inhibitors of metabolism. Following inflammation, adenosine is released from a variety of cell types in addition to neurons (e.g. endothelial cells, neutrophils, mast cells, fibroblasts). ATP is released both spinally and peripherally following inflammation or injury, and may be converted to adenosine by ecto-5'-nucleotidase contributing an additional source of adenosine. Release of adenosine from both spinal and peripheral compartments has inhibitory effects on pain transmission, as methylxanthine adenosine receptor antagonists reduce analgesia produced by agents which augment extracellular levels of adenosine spinally (morphine, 5-HT, substance P, AK inhibitors) and peripherally (AK inhibitors, AD inhibitors). Increases in extracellular adenosine availability also may contribute to antiinflammatory effects of certain agents (methotrexate, sulfasalazine, salicylates, AK inhibitors), and this could have secondary effects on pain signalling in chronic inflammation. The purpose of the present review is to consider: (a). the factors that regulate the extracellular availability of adenosine in the spinal cord and at peripheral sites; and (b). the extent to which this adenosine affects pain signalling in these two distinct compartments.
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Affiliation(s)
- Jana Sawynok
- Department of Pharmacology, Dalhousie University, Halifax, NS Canada B3H 1X5.
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Brooke RE, Pyner S, McLeish P, Buchan S, Deuchars J, Deuchars SA. Spinal cord interneurones labelled transneuronally from the adrenal gland by a GFP-herpes virus construct contain the potassium channel subunit Kv3.1b. Auton Neurosci 2002; 98:45-50. [PMID: 12144039 DOI: 10.1016/s1566-0702(02)00030-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Interneurones in the spinal cord are likely to play an important role in the generation of activity in sympathetic preganglionic neurones (SPNs) and, therefore, sympathetic outflow. Although the properties of these interneurones have rarely been studied directly, here we show that neurones antecedent to SPNs contain the voltage-gated potassium channel subunit Kv3.1b, while SPNs do not. SPNs and interneurones were labelled by injection of a green fluorescent protein expressing herpes simplex virus (HSV-GFP) into the adrenal gland. SPNs identified by concomitant tracing with Fluorogold did not contain Kv3.1b immunoreactivity. Significantly, neurones that did not contain Fluorogold and which were unlikely to be SPNs were double labelled for Kv3.1b and GFP. This indicates that spinal cord intemeurones antecedent to SPNs contain Kv3.1b. To test the role of Kv3.1b whole cell patch clamp recordings were made from SPNs and interneurones in spinal cord slices. Selective blockade of Kv3.1b containing channels with 30 microM 4-amino-pyridine (4-AP) or 500 microM tetraethylammonium chloride (TEA) revealed that this Kv subunit contributes to fast repolarisation and fast firing frequencies of interneurones in the vicinity of the IML, allowing them to fire action potentials at much higher frequencies than SPNs. This is the first time that transneuronal labelling with this viral construct has been combined with immunohistochemical detection of ion channels. In conjunction with our electrophysiological data, this highlights a role for the Kv3.1b subunit in shaping the activity of intemeurones involved in sympathetic control.
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Affiliation(s)
- Ruth E Brooke
- School of Biomedical Sciences, University of Leeds, UK
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Abstract
Upon receipt in the dorsal horn (DH) of the spinal cord, nociceptive (pain-signalling) information from the viscera, skin and other organs is subject to extensive processing by a diversity of mechanisms, certain of which enhance, and certain of which inhibit, its transfer to higher centres. In this regard, a network of descending pathways projecting from cerebral structures to the DH plays a complex and crucial role. Specific centrifugal pathways either suppress (descending inhibition) or potentiate (descending facilitation) passage of nociceptive messages to the brain. Engagement of descending inhibition by the opioid analgesic, morphine, fulfils an important role in its pain-relieving properties, while induction of analgesia by the adrenergic agonist, clonidine, reflects actions at alpha(2)-adrenoceptors (alpha(2)-ARs) in the DH normally recruited by descending pathways. However, opioids and adrenergic agents exploit but a tiny fraction of the vast panoply of mechanisms now known to be involved in the induction and/or expression of descending controls. For example, no drug interfering with descending facilitation is currently available for clinical use. The present review focuses on: (1) the organisation of descending pathways and their pathophysiological significance; (2) the role of individual transmitters and specific receptor types in the modulation and expression of mechanisms of descending inhibition and facilitation and (3) the advantages and limitations of established and innovative analgesic strategies which act by manipulation of descending controls. Knowledge of descending pathways has increased exponentially in recent years, so this is an opportune moment to survey their operation and therapeutic relevance to the improved management of pain.
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Affiliation(s)
- Mark J Millan
- Department of Psychopharmacology, Institut de Recherches Servier, 125 Chemin de Ronde, 78290 Croissy/Seine, Paris, France.
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