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Zhang W, Xiao D, Mao Q, Xia H. Role of neuroinflammation in neurodegeneration development. Signal Transduct Target Ther 2023; 8:267. [PMID: 37433768 PMCID: PMC10336149 DOI: 10.1038/s41392-023-01486-5] [Citation(s) in RCA: 97] [Impact Index Per Article: 97.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 03/22/2023] [Accepted: 05/07/2023] [Indexed: 07/13/2023] Open
Abstract
Studies in neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease and Amyotrophic lateral sclerosis, Huntington's disease, and so on, have suggested that inflammation is not only a result of neurodegeneration but also a crucial player in this process. Protein aggregates which are very common pathological phenomenon in neurodegeneration can induce neuroinflammation which further aggravates protein aggregation and neurodegeneration. Actually, inflammation even happens earlier than protein aggregation. Neuroinflammation induced by genetic variations in CNS cells or by peripheral immune cells may induce protein deposition in some susceptible population. Numerous signaling pathways and a range of CNS cells have been suggested to be involved in the pathogenesis of neurodegeneration, although they are still far from being completely understood. Due to the limited success of traditional treatment methods, blocking or enhancing inflammatory signaling pathways involved in neurodegeneration are considered to be promising strategies for the therapy of neurodegenerative diseases, and many of them have got exciting results in animal models or clinical trials. Some of them, although very few, have been approved by FDA for clinical usage. Here we comprehensively review the factors affecting neuroinflammation and the major inflammatory signaling pathways involved in the pathogenicity of neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, and Amyotrophic lateral sclerosis. We also summarize the current strategies, both in animal models and in the clinic, for the treatment of neurodegenerative diseases.
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Affiliation(s)
- Weifeng Zhang
- Laboratory of Gene Therapy, Department of Biochemistry, College of Life Sciences, Shaanxi Normal University, 199 South Chang'an Road, Xi'an, 710062, P.R. China
| | - Dan Xiao
- The State Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, Air Force Medical University, No. 169 Changle West Road, Xi'an, 710032, P.R. China
- Department of Burns and Cutaneous Surgery, Xijing Hospital, Air Force Medical University, No. 169 Changle West Road, Xi'an, 710032, China
| | - Qinwen Mao
- Department of Pathology, University of Utah, Huntsman Cancer Institute, 2000 Circle of Hope Drive, Salt Lake City, UT, 84112, USA
| | - Haibin Xia
- Laboratory of Gene Therapy, Department of Biochemistry, College of Life Sciences, Shaanxi Normal University, 199 South Chang'an Road, Xi'an, 710062, P.R. China.
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2
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Ding Z, Guo S, Luo L, Zheng Y, Gan S, Kang X, Wu X, Zhu S. Emerging Roles of Microglia in Neuro-vascular Unit: Implications of Microglia-Neurons Interactions. Front Cell Neurosci 2021; 15:706025. [PMID: 34712121 PMCID: PMC8546170 DOI: 10.3389/fncel.2021.706025] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 09/10/2021] [Indexed: 12/20/2022] Open
Abstract
Microglia, which serve as the defensive interface of the nervous system, are activated in many neurological diseases. Their role as immune responding cells has been extensively studied in the past few years. Recent studies have demonstrated that neuronal feedback can be shaped by the molecular signals received and sent by microglia. Altered neuronal activity or synaptic plasticity leads to the release of various communication messages from neurons, which in turn exert effects on microglia. Research on microglia-neuron communication has thus expanded from focusing only on neurons to the neurovascular unit (NVU). This approach can be used to explore the potential mechanism of neurovascular coupling across sophisticated receptor systems and signaling cascades in health and disease. However, it remains unclear how microglia-neuron communication happens in the brain. Here, we discuss the functional contribution of microglia to synapses, neuroimmune communication, and neuronal activity. Moreover, the current state of knowledge of bidirectional control mechanisms regarding interactions between neurons and microglia are reviewed, with a focus on purinergic regulatory systems including ATP-P2RY12R signaling, ATP-adenosine-A1Rs/A2ARs, and the ATP-pannexin 1 hemichannel. This review aims to organize recent studies to highlight the multifunctional roles of microglia within the neural communication network in health and disease.
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Affiliation(s)
- Zhe Ding
- Department of Anesthesiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Shaohui Guo
- Department of Anesthesiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Lihui Luo
- Department of Anesthesiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yueying Zheng
- Department of Anesthesiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Shuyuan Gan
- Department of Anesthesiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Xianhui Kang
- Department of Anesthesiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Xiaomin Wu
- Department of Anesthesiology, Zhejiang Provincial People's Hospital, People's Hospital of Hangzhou Medical College, Hangzhou, China
| | - Shengmei Zhu
- Department of Anesthesiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
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Dale N. Biological insights from the direct measurement of purine release. Biochem Pharmacol 2021; 187:114416. [PMID: 33444569 DOI: 10.1016/j.bcp.2021.114416] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 01/05/2021] [Accepted: 01/07/2021] [Indexed: 12/23/2022]
Abstract
Although purinergic signalling has been a well-established and accepted mechanism of chemical communication for many years, it remains important to measure the extracellular concentration of ATP and adenosine in real time. In this review I summarize the reasons why such measurements are still needed, how they provide additional mechanistic insight and give an overview of the techniques currently available to make spatially localised measurements of ATP and adenosine in real time. To illustrate the impact of direct real-time measurements, I explore CO2 and nutrient sensing in the medulla oblongata and hypothalamus. In both of these examples, the sensing involves hemichannel mediated ATP release from glial cells. For CO2 the hemichannels involved, connexin26, are directly CO2-sensitive. This mechanism contributes to the chemosensory control of breathing. In the hypothamalus, specialised glial cells, tanycytes, directly contact the cerebrospinal fluid in the 3rd ventricle and sense nutrients via sweet and umami taste receptors. Nutrient sensing by tanycytes is likely to contribute to the control of body weight as their selective stimulation alters food intake. To illustrate the importance of direct adenosine measurements, I consider the complex and multiple mechanisms of activity-dependent adenosine release in different brain regions. This activity dependent release of adenosine is likely to mediate important feedback regulation and may also be involved in controlling the sleep-wake state. I finish by briefly considering the potential of whole blood purine measurements in clinical practice.
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Affiliation(s)
- Nicholas Dale
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK.
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4
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Purinergic signaling orchestrating neuron-glia communication. Pharmacol Res 2020; 162:105253. [PMID: 33080321 DOI: 10.1016/j.phrs.2020.105253] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 09/29/2020] [Accepted: 10/09/2020] [Indexed: 12/12/2022]
Abstract
This review discusses the evidence supporting a role for ATP signaling (operated by P2X and P2Y receptors) and adenosine signaling (mainly operated by A1 and A2A receptors) in the crosstalk between neurons, astrocytes, microglia and oligodendrocytes. An initial emphasis will be given to the cooperation between adenosine receptors to sharpen information salience encoding across synapses. The interplay between ATP and adenosine signaling in the communication between astrocytes and neurons will then be presented in context of the integrative properties of the astrocytic syncytium, allowing to implement heterosynaptic depression processes in neuronal networks. The process of microglia 'activation' and its control by astrocytes and neurons will then be analyzed under the perspective of an interplay between different P2 receptors and adenosine A2A receptors. In spite of these indications of a prominent role of purinergic signaling in the bidirectional communication between neurons and glia, its therapeutical exploitation still awaits obtaining an integrated view of the spatio-temporal action of ATP signaling and adenosine signaling, clearly distinguishing the involvement of both purinergic signaling systems in the regulation of physiological processes and in the control of pathogenic-like responses upon brain dysfunction or damage.
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Abstract
17β-Estradiol (E2) is a potent steroid hormone of both gonadal and neuronal origin that exerts profound effects on neuroplasticity in several brain regions. Dendritic spine and synapse formation and rearrangements are modulated and mediated by estrogens. In this chapter, we highlighted the essential background concerning the effects of E2 on synaptic rearrangements accompanied by synaptic plasticity in E2-sensitive brain regions that mediate learning and memory, i.e., cortex and hippocampus. We also address details of the molecular mechanisms underlying E2 regulation of spine dynamics. The proposed models of action of E2 overlaps with that for well-established synaptic modulators, such as adenosine. Thus, the possible synergistic effects of those two molecules in respect to synaptic rearrangement and plasticity were presented.
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Burnstock G. Introduction to Purinergic Signalling in the Brain. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1202:1-12. [PMID: 32034706 DOI: 10.1007/978-3-030-30651-9_1] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
ATP is a cotransmitter with glutamate, noradrenaline, GABA, acetylcholine and dopamine in the brain. There is a widespread presence of both adenosine (P1) and P2 nucleotide receptors in the brain on both neurons and glial cells. Adenosine receptors play a major role in presynaptic neuromodulation, while P2X ionotropic receptors are involved in fast synaptic transmission and synaptic plasticity. P2Y G protein-coupled receptors are largely involved in presynaptic activities, as well as mediating long-term (trophic) signalling in cell proliferation, differentiation and death during development and regeneration. Both P1 and P2 receptors participate in neuron-glial interactions. Purinergic signalling is involved in control of cerebral vascular tone and remodelling and has been implicated in learning and memory, locomotor and feeding behaviour and sleep. There is increasing interest in the involvement of purinergic signalling in the pathophysiology of the CNS, including trauma, ischaemia, epilepsy, neurodegenerative diseases, neuropsychiatric and mood disorders, and cancer, including gliomas.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Royal Free Campus, Rowland Hill Street, NW3 2PF, London, UK.
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New frontiers in probing the dynamics of purinergic transmitters in vivo. Neurosci Res 2020; 152:35-43. [PMID: 31958495 DOI: 10.1016/j.neures.2020.01.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 01/03/2020] [Accepted: 01/05/2020] [Indexed: 12/16/2022]
Abstract
Purinergic transmitters such as adenosine, ADP, ATP, UTP, and UDP-glucose play important roles in a wide range of physiological processes, including the sleep-wake cycle, learning and memory, cardiovascular function, and the immune response. Moreover, impaired purinergic signaling has been implicated in various pathological conditions such as pain, migraine, epilepsy, and drug addiction. Examining the function of purinergic transmission in both health and disease requires direct, sensitive, non-invasive tools for monitoring structurally similar purinergic transmitters; ideally, these tools should have high spatial and temporal resolution in in vivo applications. Here, we review the recent progress with respect to the development and application of new methods for detecting purinergic transmitters, focusing on optical tools; in addition, we provide discussion regarding future perspectives.
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Tóth A, Antal Z, Bereczki D, Sperlágh B. Purinergic Signalling in Parkinson's Disease: A Multi-target System to Combat Neurodegeneration. Neurochem Res 2019; 44:2413-2422. [PMID: 31054067 PMCID: PMC6776560 DOI: 10.1007/s11064-019-02798-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 04/04/2019] [Accepted: 04/10/2019] [Indexed: 12/13/2022]
Abstract
Parkinson's disease (PD) is the second most common neurodegenerative disorder, characterized by progressive loss of dopaminergic neurons that results in characteristic motor and non-motor symptoms. L-3,4 dihydroxyphenylalanine (L-DOPA) is the gold standard therapy for the treatment of PD. However, long-term use of L-DOPA leads to side effects such as dyskinesias and motor fluctuation. Since purines have neurotransmitter and co-transmitter properties, the function of the purinergic system has been thoroughly studied in the nervous system. Adenosine and adenosine 5'-triphosphate (ATP) are modulators of dopaminergic neurotransmission, neuroinflammatory processes, oxidative stress, excitotoxicity and cell death via purinergic receptor subtypes. Aberrant purinergic receptor signalling can be either the cause or the result of numerous pathological conditions, including neurodegenerative disorders. Many data confirm the involvement of purinergic signalling pathways in PD. Modulation of purinergic receptor subtypes, the activity of ectonucleotidases and ATP transporters could be beneficial in the treatment of PD. We give a brief summary of the background of purinergic signalling focusing on its roles in PD. Possible targets for pharmacological treatment are highlighted.
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Affiliation(s)
- Adrián Tóth
- Department of Neurology, Faculty of Medicine, Semmelweis University, Balassa u. 6., Budapest, 1083, Hungary
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u. 43., Budapest, 1083, Hungary
- János Szentágothai School of Neurosciences, Semmelweis University School of PhD Studies, Üllői út 26., Budapest, 1085, Hungary
| | - Zsófia Antal
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u. 43., Budapest, 1083, Hungary
| | - Dániel Bereczki
- Department of Neurology, Faculty of Medicine, Semmelweis University, Balassa u. 6., Budapest, 1083, Hungary
| | - Beáta Sperlágh
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u. 43., Budapest, 1083, Hungary.
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Reklow RJ, Alvares TS, Zhang Y, Miranda Tapia AP, Biancardi V, Katzell AK, Frangos SM, Hansen MA, Toohey AW, Cass CE, Young JD, Pagliardini S, Boison D, Funk GD. The Purinome and the preBötzinger Complex - A Ménage of Unexplored Mechanisms That May Modulate/Shape the Hypoxic Ventilatory Response. Front Cell Neurosci 2019; 13:365. [PMID: 31496935 PMCID: PMC6712068 DOI: 10.3389/fncel.2019.00365] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 07/29/2019] [Indexed: 12/20/2022] Open
Abstract
Exploration of purinergic signaling in brainstem homeostatic control processes is challenging the traditional view that the biphasic hypoxic ventilatory response, which comprises a rapid initial increase in breathing followed by a slower secondary depression, reflects the interaction between peripheral chemoreceptor-mediated excitation and central inhibition. While controversial, accumulating evidence supports that in addition to peripheral excitation, interactions between central excitatory and inhibitory purinergic mechanisms shape this key homeostatic reflex. The objective of this review is to present our working model of how purinergic signaling modulates the glutamatergic inspiratory synapse in the preBötzinger Complex (key site of inspiratory rhythm generation) to shape the hypoxic ventilatory response. It is based on the perspective that has emerged from decades of analysis of glutamatergic synapses in the hippocampus, where the actions of extracellular ATP are determined by a complex signaling system, the purinome. The purinome involves not only the actions of ATP and adenosine at P2 and P1 receptors, respectively, but diverse families of enzymes and transporters that collectively determine the rate of ATP degradation, adenosine accumulation and adenosine clearance. We summarize current knowledge of the roles played by these different purinergic elements in the hypoxic ventilatory response, often drawing on examples from other brain regions, and look ahead to many unanswered questions and remaining challenges.
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Affiliation(s)
- Robert J. Reklow
- Department of Physiology, Women and Children’s Health Research Institute, Neuroscience and Mental Health Institute, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Tucaaue S. Alvares
- Department of Physiology, Women and Children’s Health Research Institute, Neuroscience and Mental Health Institute, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Yong Zhang
- Department of Physiology, Women and Children’s Health Research Institute, Neuroscience and Mental Health Institute, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Ana P. Miranda Tapia
- Department of Physiology, Women and Children’s Health Research Institute, Neuroscience and Mental Health Institute, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Vivian Biancardi
- Department of Physiology, Women and Children’s Health Research Institute, Neuroscience and Mental Health Institute, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Alexis K. Katzell
- Department of Physiology, Women and Children’s Health Research Institute, Neuroscience and Mental Health Institute, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Sara M. Frangos
- Department of Physiology, Women and Children’s Health Research Institute, Neuroscience and Mental Health Institute, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Megan A. Hansen
- Department of Physiology, Women and Children’s Health Research Institute, Neuroscience and Mental Health Institute, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Alexander W. Toohey
- Department of Physiology, Women and Children’s Health Research Institute, Neuroscience and Mental Health Institute, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Carol E. Cass
- Professor Emerita, Department of Oncology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - James D. Young
- Department of Physiology, Women and Children’s Health Research Institute, Neuroscience and Mental Health Institute, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Silvia Pagliardini
- Department of Physiology, Women and Children’s Health Research Institute, Neuroscience and Mental Health Institute, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Detlev Boison
- Department of Neurosurgery, Robert Wood Johnson Medical School and New Jersey Medical School, Rutgers University, New Brunswick, NJ, United States
| | - Gregory D. Funk
- Department of Physiology, Women and Children’s Health Research Institute, Neuroscience and Mental Health Institute, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
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Beamer E, Conte G, Engel T. ATP release during seizures - A critical evaluation of the evidence. Brain Res Bull 2019; 151:65-73. [PMID: 30660718 DOI: 10.1016/j.brainresbull.2018.12.021] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 12/06/2018] [Accepted: 12/20/2018] [Indexed: 01/17/2023]
Abstract
That adenosine 5' triphosphate (ATP) functions as an extracellular signaling molecule has been established since the 1970s. Ubiquitous throughout the body as the principal molecular store of intracellular energy, ATP has a short extracellular half-life and is difficult to measure directly. Extracellular ATP concentrations are dependent both on the rate of cellular release and of enzymatic degradation. Some findings from in vitro studies suggest that extracellular ATP concentrations increase during high levels of neuronal activity and seizure-like events in hippocampal slices. Pharmacological studies suggest that antagonism of ATP-sensitive purinergic receptors can suppress the severity of seizures and block epileptogenesis. Directly measuring extracellular ATP concentrations in the brain, however, has a number of specific challenges, notably, the rapid hydrolysis of ATP and huge gradient between intracellular and extracellular compartments. Two studies using microdialysis found no change in extracellular ATP in the hippocampus of rats during experimentally-induced status epilepticus. One of which demonstrated that ATP increased measurably, only in the presence of ectoATPase inhibitors, with the other study demonstrating increases only during later spontaneous seizures. Current evidence is mixed and seems highly dependent on the model used and method of detection. More sensitive methods of detection with higher spatial resolution, which induce less tissue disruption will be necessary to provide evidence for or against the hypothesis of seizure-induced elevations in extracellular ATP. Here we describe the current hypothesis for ATP release during seizures and its role in epileptogenesis, describe the technical challenges involved and critically examine the current evidence.
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Affiliation(s)
- Edward Beamer
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, D02YN77, Dublin, Ireland.
| | - Giorgia Conte
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, D02YN77, Dublin, Ireland
| | - Tobias Engel
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, D02YN77, Dublin, Ireland
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Morales-Figueroa GE, Rivera-Ramírez N, González-Pantoja R, Escamilla-Sánchez J, García-Hernández U, Galván EJ, Arias-Montaño JA. Adenosine A 2A and histamine H 3 receptors interact at the cAMP/PKA pathway to modulate depolarization-evoked [ 3H]-GABA release from rat striato-pallidal terminals. Purinergic Signal 2018; 15:85-93. [PMID: 30565027 DOI: 10.1007/s11302-018-9638-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 11/20/2018] [Indexed: 02/06/2023] Open
Abstract
We previously reported that the activation of histamine H3 receptors (H3Rs) selectively counteracts the facilitatory action of adenosine A2A receptors (A2ARs) on GABA release from rat globus pallidus (GP) isolated nerve terminals (synaptosomes). In this work, we examined the mechanisms likely to underlie this functional interaction. Three possibilities were explored: (a) changes in receptor affinity for agonists induced by physical A2AR/H3R interaction, (b) opposite actions of A2ARs and H3Rs on depolarization-induced Ca2+ entry, and (c) an A2AR/H3R interaction at the level of adenosine 3',5'-cyclic monophosphate (cAMP) formation. In GP synaptosomal membranes, H3R activation with immepip reduced A2AR affinity for the agonist 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamidoadenosine hydrochloride hydrate (CGS-21680) (Ki control 4.53 nM; + immepip 9.32 nM), whereas A2AR activation increased H3R affinity for immepip (Ki control 0.63 nM; + CGS-21680 0.26 nM). Neither A2AR activation nor H3R stimulation modified calcium entry through voltage-gated calcium channels in GP synaptosomes, as evaluated by microfluorometry. A2AR-mediated facilitation of depolarization-evoked [2,3-3H]-γ-aminobutyric acid ([3H]-GABA) release from GP synaptosomes (130.4 ± 3.6% of control values) was prevented by the PKA inhibitor H-89 and mimicked by the adenylyl cyclase activator forskolin or by 8-Bromo-cAMP, a membrane permeant cAMP analogue (169.5 ± 17.3 and 149.5 ± 14.5% of controls). H3R activation failed to reduce the facilitation of [3H]-GABA release induced by 8-Bromo-cAMP. In GP slices, A2AR activation stimulated cAMP accumulation (290% of basal) and this effect was reduced (- 75%) by H3R activation. These results indicate that in striato-pallidal nerve terminals, A2ARs and H3Rs interact at the level of cAMP formation to modulate PKA activity and thus GABA release.
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Affiliation(s)
- Guadalupe-Elide Morales-Figueroa
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, AV. IPN 2508, Ciudad de México, México
| | - Nayeli Rivera-Ramírez
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, AV. IPN 2508, Ciudad de México, México
| | - Raúl González-Pantoja
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, AV. IPN 2508, Ciudad de México, México
| | - Juan Escamilla-Sánchez
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, AV. IPN 2508, Ciudad de México, México
| | - Ubaldo García-Hernández
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, AV. IPN 2508, Ciudad de México, México
| | - Emilio J Galván
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del IPN, AV. IPN 2508, 07360, MÉXICO, México
| | - José-Antonio Arias-Montaño
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, AV. IPN 2508, Ciudad de México, México.
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Bossi S, Helleringer R, Galante M, Monlleó E, Trapero A, Rovira X, Daniel H, Llebaria A, McLean H. A Light-Controlled Allosteric Modulator Unveils a Role for mGlu 4 Receptors During Early Stages of Ischemia in the Rodent Cerebellar Cortex. Front Cell Neurosci 2018; 12:449. [PMID: 30542267 PMCID: PMC6277836 DOI: 10.3389/fncel.2018.00449] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 11/07/2018] [Indexed: 01/15/2023] Open
Abstract
Metabotropic glutamate receptors (mGlus) are G Protein coupled-receptors that modulate synaptic transmission and plasticity in the central nervous system. Some act as autoreceptors to control neurotransmitter release at excitatory synapses and have become attractive targets for drug therapy to treat certain neurological disorders. However, the high degree of sequence conservation around the glutamate binding site makes the development of subtype-specific orthosteric ligands difficult to achieve. This problem can be circumvented by designing molecules that target specific less well conserved allosteric sites. One such allosteric drug, the photo-switchable compound OptoGluNAM4.1, has been recently employed to reversibly inhibit the activity of metabotropic glutamate 4 (mGlu4) receptors in cell cultures and in vivo. We studied OptoGluNAM4.1 as a negative modulator of neurotransmission in rodent cerebellar slices at the parallel fiber – Purkinje cell synapse. Our data show that OptoGluNAM4.1 antagonizes pharmacological activation of mGlu4 receptors in a fully reversible and photo-controllable manner. In addition, for the first time, this new allosteric modulator allowed us to demonstrate that, in brain slices from the rodent cerebellar cortex, mGlu4 receptors are endogenously activated in excitotoxic conditions, such as the early phases of simulated cerebellar ischemia, which is associated with elevated levels of extracellular glutamate. These findings support OptoGluNAM4.1 as a promising new tool for unraveling the role of mGlu4 receptors in the central nervous system in physio-pathological conditions.
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Affiliation(s)
- Simon Bossi
- Pharmacologie et Biochimie de la Synapse, Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, Université Paris-Sud - CNRS, UMR 9197, Orsay, France
| | - Romain Helleringer
- Pharmacologie et Biochimie de la Synapse, Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, Université Paris-Sud - CNRS, UMR 9197, Orsay, France
| | - Micaela Galante
- Pharmacologie et Biochimie de la Synapse, Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, Université Paris-Sud - CNRS, UMR 9197, Orsay, France
| | - Ester Monlleó
- MCS, Laboratory of Medicinal Chemistry, Institute for Advanced Chemistry of Catalonia (IQAC-CSIC), Barcelona, Spain
| | - Ana Trapero
- MCS, Laboratory of Medicinal Chemistry, Institute for Advanced Chemistry of Catalonia (IQAC-CSIC), Barcelona, Spain
| | - Xavier Rovira
- Molecular Photopharmacology Research Group, The Tissue Repair and Regeneration Laboratory, University of Vic - Central University of Catalonia, Vic, Spain
| | - Hervé Daniel
- Pharmacologie et Biochimie de la Synapse, Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, Université Paris-Sud - CNRS, UMR 9197, Orsay, France
| | - Amadeu Llebaria
- MCS, Laboratory of Medicinal Chemistry, Institute for Advanced Chemistry of Catalonia (IQAC-CSIC), Barcelona, Spain
| | - Heather McLean
- Pharmacologie et Biochimie de la Synapse, Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, Université Paris-Sud - CNRS, UMR 9197, Orsay, France
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Ventura ALM, Dos Santos-Rodrigues A, Mitchell CH, Faillace MP. Purinergic signaling in the retina: From development to disease. Brain Res Bull 2018; 151:92-108. [PMID: 30458250 DOI: 10.1016/j.brainresbull.2018.10.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 09/14/2018] [Accepted: 10/23/2018] [Indexed: 02/07/2023]
Abstract
Retinal injuries and diseases are major causes of human disability involving vision impairment by the progressive and permanent loss of retinal neurons. During development, assembly of this tissue entails a successive and overlapping, signal-regulated engagement of complex events that include proliferation of progenitors, neurogenesis, cell death, neurochemical differentiation and synaptogenesis. During retinal damage, several of these events are re-activated with both protective and detrimental consequences. Purines and pyrimidines, along with their metabolites are emerging as important molecules regulating both retinal development and the tissue's responses to damage. The present review provides an overview of the purinergic signaling in the developing and injured retina. Recent findings on the presence of vesicular and channel-mediated ATP release by retinal and retinal pigment epithelial cells, adenosine synthesis and release, expression of receptors and intracellular signaling pathways activated by purinergic signaling in retinal cells are reported. The pathways by which purinergic receptors modulate retinal cell proliferation, migration and death of retinal cells during development and injury are summarized. The contribution of nucleotides to the self-repair of the injured zebrafish retina is also discussed.
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Affiliation(s)
- Ana Lucia Marques Ventura
- Department of Neurobiology, Neuroscience Program, Fluminense Federal University, Niterói, RJ, Brazil.
| | | | - Claire H Mitchell
- Department of Anatomy and Cell Biology, Ophthalmology, and Physiology, University of Pennsylvania, Philadelphia, PA 19104, United States.
| | - Maria Paula Faillace
- Instituto de Fisiología y Biofísica Prof. Bernardo Houssay (IFIBIO-Houssay), Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina; Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.
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14
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Welsh TG, Kucenas S. Purinergic signaling in oligodendrocyte development and function. J Neurochem 2018; 145:6-18. [PMID: 29377124 DOI: 10.1111/jnc.14315] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 01/08/2018] [Accepted: 01/21/2018] [Indexed: 12/31/2022]
Abstract
Myelin, an insulating membrane that enables rapid action potential propagation, is an essential component of an efficient, functional vertebrate nervous system. Oligodendrocytes, the myelinating glia of the central nervous system (CNS), produce myelin throughout the CNS, which requires continuous proliferation, migration, and differentiation of oligodendrocyte progenitor cells. Because myelination is essential for efficient neurotransmission, researchers hypothesize that neuronal signals may regulate the cascade of events necessary for this process. The ability of oligodendrocytes and oligodendrocyte progenitor cells to detect and respond to neuronal activity is becoming increasingly appreciated, although the specific signals involved are still a matter of debate. Recent evidence from multiple studies points to purinergic signaling as a potential regulator of oligodendrocyte development and differentiation. Adenosine triphosphate (ATP) and its derivatives are potent signaling ligands with receptors expressed on many populations of cells in the nervous system, including cells of the oligodendrocyte lineage. Release of ATP into the extracellular space can initiate a multitude of signaling events, and these downstream signals are specific to the particular purinergic receptor (or receptors) expressed, and whether enzymes are present to hydrolyze ATP to its derivatives adenosine diphosphate and adenosine, each of which can activate their own unique downstream signaling cascades. This review will introduce purinergic signaling in the CNS and discuss evidence for its effects on oligodendrocyte proliferation, differentiation, and myelination. We will review sources of extracellular purines in the nervous system and how changes in purinergic receptor expression may be coupled to oligodendrocyte differentiation. We will also briefly discuss purinergic signaling in injury and diseases of the CNS.
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Affiliation(s)
- Taylor G Welsh
- Neuroscience Graduate Program, Charlottesville, Virginia, USA
| | - Sarah Kucenas
- Neuroscience Graduate Program, Charlottesville, Virginia, USA.,Department of Biology, University of Virginia, Charlottesville, Virginia, USA
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15
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Madry C, Arancibia-Cárcamo IL, Kyrargyri V, Chan VTT, Hamilton NB, Attwell D. Effects of the ecto-ATPase apyrase on microglial ramification and surveillance reflect cell depolarization, not ATP depletion. Proc Natl Acad Sci U S A 2018; 115:E1608-E1617. [PMID: 29382767 PMCID: PMC5816168 DOI: 10.1073/pnas.1715354115] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Microglia, the brain's innate immune cells, have highly motile processes which constantly survey the brain to detect infection, remove dying cells, and prune synapses during brain development. ATP released by tissue damage is known to attract microglial processes, but it is controversial whether an ambient level of ATP is needed to promote constant microglial surveillance in the normal brain. Applying the ATPase apyrase, an enzyme which hydrolyzes ATP and ADP, reduces microglial process ramification and surveillance, suggesting that ambient ATP/ADP maintains microglial surveillance. However, attempting to raise the level of ATP/ADP by blocking the endogenous ecto-ATPase (termed NTPDase1/CD39), which also hydrolyzes ATP/ADP, does not affect the cells' ramification or surveillance, nor their membrane currents, which respond to even small rises of extracellular [ATP] or [ADP] with the activation of K+ channels. This indicates a lack of detectable ambient ATP/ADP and ecto-ATPase activity, contradicting the results with apyrase. We resolve this contradiction by demonstrating that contamination of commercially available apyrase by a high K+ concentration reduces ramification and surveillance by depolarizing microglia. Exposure to the same K+ concentration (without apyrase added) reduced ramification and surveillance as with apyrase. Dialysis of apyrase to remove K+ retained its ATP-hydrolyzing activity but abolished the microglial depolarization and decrease of ramification produced by the undialyzed enzyme. Thus, applying apyrase affects microglia by an action independent of ATP, and no ambient purinergic signaling is required to maintain microglial ramification and surveillance. These results also have implications for hundreds of prior studies that employed apyrase to hydrolyze ATP/ADP.
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Affiliation(s)
- Christian Madry
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom;
- Institute of Neurophysiology, Charité Universitätsmedizin, 10117 Berlin, Germany
| | - I Lorena Arancibia-Cárcamo
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
| | - Vasiliki Kyrargyri
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
| | - Victor T T Chan
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
| | - Nicola B Hamilton
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom;
- Wolfson Centre for Age-Related Diseases, King's College London, London SE1 1UL, United Kingdom
| | - David Attwell
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom;
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16
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Nguyen MD, Wang Y, Ganesana M, Venton BJ. Transient Adenosine Release Is Modulated by NMDA and GABA B Receptors. ACS Chem Neurosci 2017; 8:376-385. [PMID: 28071892 DOI: 10.1021/acschemneuro.6b00318] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Adenosine is a neuroprotective agent that modulates neurotransmission and is modulated by other neurotransmitters. Spontaneous, transient adenosine is a recently discovered mode of signaling where adenosine is released and cleared from the extracellular space quickly, in less than three seconds. Spontaneous adenosine release is regulated by adenosine A1 and A2a receptors, but regulation by other neurotransmitter receptors has not been studied. Here, we examined the effect of glutamate and GABA receptors on the concentration and frequency of spontaneous, transient adenosine release by measuring adenosine with fast-scan cyclic voltammetry in the rat caudate-putamen. The glutamate NMDA antagonist, 3-(R-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP, 6.25 mg/kg i.p.), increased the frequency of adenosine transients and the concentration of individual transients, but NMDA (agonist, 50 mg/kg, i.p.) did not change the frequency. In contrast, antagonists of other glutamate receptors had no effect on the frequency or concentration of transient adenosine release, including the AMPA antagonist NBQX (15 mg/kg i.p.) and the mGlu2/3 glutamate receptor antagonist LY 341495 (5 mg/kg i.p.). The GABAB antagonist CGP 52432 (30 mg/kg i.p.) significantly decreased the number of adenosine release events while the GABAB agonist baclofen (4 mg/kg i.p.) increased the frequency of adenosine release. The GABAA antagonist bicuculline (5 mg/kg i.p.) had no significant effects on adenosine. NMDA and GABAB likely act presynaptically, affecting the overall cell excitability for vesicular release. The ability to regulate adenosine with NMDA and GABAB receptors will help control the modulatory effects of transient adenosine release.
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Affiliation(s)
- Michael D. Nguyen
- Department
of Chemistry and
Neuroscience Graduate Program, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Ying Wang
- Department
of Chemistry and
Neuroscience Graduate Program, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Mallikarjunarao Ganesana
- Department
of Chemistry and
Neuroscience Graduate Program, University of Virginia, Charlottesville, Virginia 22904, United States
| | - B. Jill Venton
- Department
of Chemistry and
Neuroscience Graduate Program, University of Virginia, Charlottesville, Virginia 22904, United States
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17
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Dale N, Sebastião AM. Dissecting neurovascular coupling mechanisms: a role for adenosine A 2A receptor: An Editorial highlight for 'Correlation of transient adenosine release and oxygen changes in the caudate-putamen'. J Neurochem 2016; 140:10-12. [PMID: 27981581 DOI: 10.1111/jnc.13896] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Revised: 10/27/2016] [Accepted: 11/08/2016] [Indexed: 11/28/2022]
Abstract
Read the highlighted article 'Correlation of transient adenosine release and oxygen changes in the caudate-putamen' on page 13.
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Affiliation(s)
- Nicholas Dale
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Ana Maria Sebastião
- 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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18
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Sweeney P, Qi Y, Xu Z, Yang Y. Activation of hypothalamic astrocytes suppresses feeding without altering emotional states. Glia 2016; 64:2263-2273. [PMID: 27658520 DOI: 10.1002/glia.23073] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 08/01/2016] [Accepted: 09/08/2016] [Indexed: 02/06/2023]
Abstract
Emerging evidence shows that hypothalamic astrocytes react to and counteract energy surfeit produced by high-fat diet (HFD) feeding. However, the functional role of astrocytes in the control of energy states and the underlying molecular mechanism(s) during physiological conditions remain largely underexplored. In the present study, by taking advantage of spatiotemporally precise optogenetic approaches, real-time measurements of extracellular adenosine, and behavioral assays, we find that optogenetic stimulation of astrocytes localized in the medial basal hypothalamus (MBH) suppresses food intake in a frequency dependent manner with high frequency, but not low frequency, stimulation of astrocytes reducing food intake. Furthermore, stimulation of MBH astrocytes diminishes orexigenic ghrelin or fasting-induced hyperphagia without effecting anxiety-related behavior. Consistent with a frequency dependent role for MBH astrocytes in feeding behavior, optogenetic stimulation of MBH astrocytes increases extracellular levels of adenosine in a frequency dependent manner. Collectively, our results provide new insights into the role of astrocytes in physiological functions during naturally occurring behaviors, such as feeding. GLIA 2016;64:2263-2273.
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Affiliation(s)
- Patrick Sweeney
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, New York
| | - Yong Qi
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, New York.,Zhengzhou University People's Hospital (He'nan Provincial People's Hospital), Zhengzhou, 450003, China
| | - Zhenping Xu
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, New York
| | - Yunlei Yang
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, New York.
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19
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Dar MS. Ethanol-Induced Cerebellar Ataxia: Cellular and Molecular Mechanisms. THE CEREBELLUM 2016; 14:447-65. [PMID: 25578036 DOI: 10.1007/s12311-014-0638-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The cerebellum is an important target of ethanol toxicity given that cerebellar ataxia is the most consistent physical manifestation of acute ethanol consumption. Despite the significance of the cerebellum in ethanol-induced cerebellar ataxia (EICA), the cellular and molecular mechanisms underlying EICA are incompletely understood. However, two important findings have shed greater light on this phenomenon. First, ethanol-induced blockade of cerebellar adenosine uptake in rodent models points to a role for adenosinergic A1 modulation of EICA. Second, the consistent observation that intracerebellar administration of nicotine in mice leads to antagonism of EICA provides evidence for a critical role of cerebellar nitric oxide (NO) in EICA reversal. Based on these two important findings, this review discusses the potential molecular events at two key synaptic sites (mossy fiber-granule cell-Golgi cell (MGG synaptic site) and granule cell parallel fiber-Purkinje cell (GPP synaptic site) that lead to EICA. Specifically, ethanol-induced neuronal NOS inhibition at the MGG synaptic site acts as a critical trigger for Golgi cell activation which leads to granule cell deafferentation. Concurrently, ethanol-induced inhibition of adenosine uptake at the GPP synaptic site produces adenosine accumulation which decreases glutamate release and leads to the profound activation of Purkinje cells (PCs). These molecular events at the MGG and GPP synaptic sites are mutually reinforcing and lead to cerebellar dysfunction, decreased excitatory output of deep cerebellar nuclei, and EICA. The critical importance of PCs as the sole output of the cerebellar cortex suggests normalization of PC function could have important therapeutic implications.
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Affiliation(s)
- M Saeed Dar
- Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, NC, 27858, USA,
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20
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Abstract
There is a brief introductory summary of purinergic signaling involving ATP storage, release, and ectoenzymatic breakdown, and the current classification of receptor subtypes for purines and pyrimidines. The review then describes purinergic mechanosensory transduction involved in visceral, cutaneous, and musculoskeletal nociception and on the roles played by receptor subtypes in neuropathic and inflammatory pain. Multiple purinoceptor subtypes are involved in pain pathways both as an initiator and modulator. Activation of homomeric P2X3 receptors contributes to acute nociception and activation of heteromeric P2X2/3 receptors appears to modulate longer-lasting nociceptive sensitivity associated with nerve injury or chronic inflammation. In neuropathic pain activation of P2X4, P2X7, and P2Y12 receptors on microglia may serve to maintain nociceptive sensitivity through complex neural-glial cell interactions and antagonists to these receptors reduce neuropathic pain. Potential therapeutic approaches involving purinergic mechanisms will be discussed.
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21
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Di Angelantonio S, Bertollini C, Piccinin S, Rosito M, Trettel F, Pagani F, Limatola C, Ragozzino D. Basal adenosine modulates the functional properties of AMPA receptors in mouse hippocampal neurons through the activation of A1R A2AR and A3R. Front Cell Neurosci 2015; 9:409. [PMID: 26528137 PMCID: PMC4601258 DOI: 10.3389/fncel.2015.00409] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 09/25/2015] [Indexed: 11/30/2022] Open
Abstract
Adenosine is a widespread neuromodulator within the CNS and its extracellular level is increased during hypoxia or intense synaptic activity, modulating pre- and postsynaptic sites. We studied the neuromodulatory action of adenosine on glutamatergic currents in the hippocampus, showing that activation of multiple adenosine receptors (ARs) by basal adenosine impacts postsynaptic site. Specifically, the stimulation of both A1R and A3R reduces AMPA currents, while A2AR has an opposite potentiating effect. The effect of ARs stimulation on glutamatergic currents in hippocampal cultures was investigated using pharmacological and genetic approaches. A3R inhibition by MRS1523 increased GluR1-Ser845 phosphorylation and potentiated AMPA current amplitude, increasing the apparent affinity for the agonist. A similar effect was observed blocking A1R with DPCPX or by genetic deletion of either A3R or A1R. Conversely, impairment of A2AR reduced AMPA currents, and decreased agonist sensitivity. Consistently, in hippocampal slices, ARs activation by AR agonist NECA modulated glutamatergic current amplitude evoked by AMPA application or afferent fiber stimulation. Opposite effects of AR subtypes stimulation are likely associated to changes in GluR1 phosphorylation and represent a novel mechanism of physiological modulation of glutamatergic transmission by adenosine, likely acting in normal conditions in the brain, depending on the level of extracellular adenosine and the distribution of AR subtypes.
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Affiliation(s)
- Silvia Di Angelantonio
- Istituto Pasteur-Fondazione Cenci Bolognetti and Dipartimento di Fisiologia e Farmacologia, Sapienza Università di Roma Roma, Italy ; Center for Life Nanoscience, Istituto Italiano di Tecnologia Rome, Italy
| | - Cristina Bertollini
- Istituto Pasteur-Fondazione Cenci Bolognetti and Dipartimento di Fisiologia e Farmacologia, Sapienza Università di Roma Roma, Italy
| | - Sonia Piccinin
- Istituto Pasteur-Fondazione Cenci Bolognetti and Dipartimento di Fisiologia e Farmacologia, Sapienza Università di Roma Roma, Italy
| | - Maria Rosito
- Istituto Pasteur-Fondazione Cenci Bolognetti and Dipartimento di Fisiologia e Farmacologia, Sapienza Università di Roma Roma, Italy
| | - Flavia Trettel
- Istituto Pasteur-Fondazione Cenci Bolognetti and Dipartimento di Fisiologia e Farmacologia, Sapienza Università di Roma Roma, Italy
| | - Francesca Pagani
- Center for Life Nanoscience, Istituto Italiano di Tecnologia Rome, Italy
| | - Cristina Limatola
- Istituto Pasteur-Fondazione Cenci Bolognetti and Dipartimento di Fisiologia e Farmacologia, Sapienza Università di Roma Roma, Italy ; Neuromed, Istituto di Ricovero e Cura a Carattere Scientifico Pozzilli, Italy
| | - Davide Ragozzino
- Istituto Pasteur-Fondazione Cenci Bolognetti and Dipartimento di Fisiologia e Farmacologia, Sapienza Università di Roma Roma, Italy ; Neuromed, Istituto di Ricovero e Cura a Carattere Scientifico Pozzilli, Italy
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22
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Frenguelli BG, Wall MJ. Combined electrophysiological and biosensor approaches to study purinergic regulation of epileptiform activity in cortical tissue. J Neurosci Methods 2015; 260:202-14. [PMID: 26381061 DOI: 10.1016/j.jneumeth.2015.09.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 09/05/2015] [Accepted: 09/07/2015] [Indexed: 12/16/2022]
Abstract
BACKGROUND Cortical brain slices offer a readily accessible experimental model of a region of the brain commonly affected by epilepsy. The diversity of recording techniques, seizure-promoting protocols and mutant mouse models provides a rich diversity of avenues of investigation, which is facilitated by the regular arrangement of distinct neuronal populations and afferent fibre pathways, particularly in the hippocampus. NEW METHOD AND RESULTS We have been interested in the regulation of seizure activity in hippocampal and neocortical slices by the purines, adenosine and ATP. Via the use of microelectrode biosensors we have been able to measure the release of these important neuroactive compounds simultaneously with on-going epileptiform activity, even of brief durations. In addition, detailed numerical analysis and computational modelling has produced new insights into the kinetics and spatial distribution of elevations in purine concentration that occur during seizure activity. COMPARISON AND CONCLUSIONS Such an approach allows the spatio-temporal characteristics of neurotransmitter/neuromodulator release to be directly correlated with electrophysiological measures of synaptic and seizure activity, and can provide greater insight into the role of purines in epilepsy.
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Affiliation(s)
| | - Mark J Wall
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
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23
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Burnstock G. An introduction to the roles of purinergic signalling in neurodegeneration, neuroprotection and neuroregeneration. Neuropharmacology 2015; 104:4-17. [PMID: 26056033 DOI: 10.1016/j.neuropharm.2015.05.031] [Citation(s) in RCA: 141] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 05/19/2015] [Accepted: 05/20/2015] [Indexed: 12/21/2022]
Abstract
Purinergic signalling appears to play important roles in neurodegeneration, neuroprotection and neuroregeneration. Initially there is a brief summary of the background of purinergic signalling, including release of purines and pyrimidines from neural and non-neural cells and their ectoenzymatic degradation, and the current characterisation of P1 (adenosine), and P2X (ion channel) and P2Y (G protein-coupled) nucleotide receptor subtypes. There is also coverage of the localization and roles of purinoceptors in the healthy central nervous system. The focus is then on the roles of purinergic signalling in trauma, ischaemia, stroke and in neurodegenerative diseases, including Alzheimer's, Parkinson's and Huntington's diseases, as well as multiple sclerosis and amyotrophic lateral sclerosis. Neuroprotective mechanisms involving purinergic signalling are considered and its involvement in neuroregeneration, including the role of adult neural stem/progenitor cells. This article is part of the Special Issue entitled 'Purines in Neurodegeneration and Neuroregeneration'.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London NW3 2PF, UK; Department of Pharmacology and Therapeutics, The University of Melbourne, Australia.
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24
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Nguyen MD, Venton BJ. Fast-scan Cyclic Voltammetry for the Characterization of Rapid Adenosine Release. Comput Struct Biotechnol J 2014; 13:47-54. [PMID: 26900429 PMCID: PMC4720017 DOI: 10.1016/j.csbj.2014.12.006] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 12/19/2014] [Accepted: 12/23/2014] [Indexed: 12/20/2022] Open
Abstract
Adenosine is a signaling molecule and downstream product of ATP that acts as a neuromodulator. Adenosine regulates physiological processes, such as neurotransmission and blood flow, on a time scale of minutes to hours. Recent developments in electrochemical techniques, including fast-scan cyclic voltammetry (FSCV), have allowed direct detection of adenosine with sub-second temporal resolution. FSCV studies have revealed a novel mode of rapid signaling that lasts only a few seconds. This rapid release of adenosine can be evoked by electrical or mechanical stimulations or it can be observed spontaneously without stimulation. Adenosine signaling on this time scale is activity dependent; however, the mode of release is not fully understood. Rapid adenosine release modulates oxygen levels and evoked dopamine release, indicating that adenosine may have a rapid modulatory role. In this review, we outline how FSCV can be used to detect adenosine release, compare FSCV with other techniques used to measure adenosine, and present an overview of adenosine signaling that has been characterized using FSCV. These studies point to a rapid mode of adenosine modulation, whose mechanism and function will continue to be characterized in the future.
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Affiliation(s)
- Michael D Nguyen
- Department of Chemistry, University of Virginia, McCormick Road, PO BOX 400319, Charlottesville, VA 22904, United States
| | - B Jill Venton
- Department of Chemistry, University of Virginia, McCormick Road, PO BOX 400319, Charlottesville, VA 22904, United States
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25
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Wall MJ, Richardson MJE. Localized adenosine signaling provides fine-tuned negative feedback over a wide dynamic range of neocortical network activities. J Neurophysiol 2014; 113:871-82. [PMID: 25392170 DOI: 10.1152/jn.00620.2014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Although the patterns of activity produced by neocortical networks are now better understood, how these states are activated, sustained, and terminated still remains unclear. Negative feedback by the endogenous neuromodulator adenosine may potentially play an important role, as it can be released by activity and there is dense A1 receptor expression in the neocortex. Using electrophysiology, biosensors, and modeling, we have investigated the properties of adenosine signaling during physiological and pathological network activity in rat neocortical slices. Both low- and high-rate network activities were reduced by A1 receptor activation and enhanced by block of A1 receptors, consistent with activity-dependent adenosine release. Since the A1 receptors were neither saturated nor completely unoccupied during either low- or high-rate activity, adenosine signaling provides a negative-feedback mechanism with a wide dynamic range. Modeling and biosensor experiments show that during high-rate activity increases in extracellular adenosine concentration are highly localized and are uncorrelated over short distances that are certainly<500 μm. Modeling also predicts that the slow rise of the purine waveform cannot be from diffusion from distal release sites but more likely results from uptake and metabolism. The inability to directly measure adenosine release during low-rate activity, although it is present, is probably a consequence of small localized increases in adenosine concentration that are rapidly diminished by diffusion and active removal mechanisms. Saturation of such removal mechanisms when higher concentrations of adenosine are released results in the accumulation of inosine, explaining the strong purine signal during high-rate activity.
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Affiliation(s)
- Mark J Wall
- School of Life Sciences, University of Warwick, Coventry, United Kingdom; and
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26
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Mutafova-Yambolieva VN, Durnin L. The purinergic neurotransmitter revisited: a single substance or multiple players? Pharmacol Ther 2014; 144:162-91. [PMID: 24887688 PMCID: PMC4185222 DOI: 10.1016/j.pharmthera.2014.05.012] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 05/23/2014] [Indexed: 12/20/2022]
Abstract
The past half century has witnessed tremendous advances in our understanding of extracellular purinergic signaling pathways. Purinergic neurotransmission, in particular, has emerged as a key contributor in the efficient control mechanisms in the nervous system. The identity of the purine neurotransmitter, however, remains controversial. Identifying it is difficult because purines are present in all cell types, have a large variety of cell sources, and are released via numerous pathways. Moreover, studies on purinergic neurotransmission have relied heavily on indirect measurements of integrated postjunctional responses that do not provide direct information for neurotransmitter identity. This paper discusses experimental support for adenosine 5'-triphosphate (ATP) as a neurotransmitter and recent evidence for possible contribution of other purines, in addition to or instead of ATP, in chemical neurotransmission in the peripheral, enteric and central nervous systems. Sites of release and action of purines in model systems such as vas deferens, blood vessels, urinary bladder and chromaffin cells are discussed. This is preceded by a brief discussion of studies demonstrating storage of purines in synaptic vesicles. We examine recent evidence for cell type targets (e.g., smooth muscle cells, interstitial cells, neurons and glia) for purine neurotransmitters in different systems. This is followed by brief discussion of mechanisms of terminating the action of purine neurotransmitters, including extracellular nucleotide hydrolysis and possible salvage and reuptake in the cell. The significance of direct neurotransmitter release measurements is highlighted. Possibilities for involvement of multiple purines (e.g., ATP, ADP, NAD(+), ADP-ribose, adenosine, and diadenosine polyphosphates) in neurotransmission are considered throughout.
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Affiliation(s)
| | - Leonie Durnin
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, United States
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27
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Ross AE, Nguyen MD, Privman E, Venton BJ. Mechanical stimulation evokes rapid increases in extracellular adenosine concentration in the prefrontal cortex. J Neurochem 2014; 130:50-60. [PMID: 24606335 PMCID: PMC4065624 DOI: 10.1111/jnc.12711] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 02/28/2014] [Accepted: 03/05/2014] [Indexed: 12/22/2022]
Abstract
Mechanical perturbations can release ATP, which is broken down to adenosine. In this work, we used carbon-fiber microelectrodes and fast-scan cyclic voltammetry to measure mechanically stimulated adenosine in the brain by lowering the electrode 50 μm. Mechanical stimulation evoked adenosine in vivo (average: 3.3 ± 0.6 μM) and in brain slices (average: 0.8 ± 0.1 μM) in the prefrontal cortex. The release was transient, lasting 18 ± 2 s. Lowering a 15-μm-diameter glass pipette near the carbon-fiber microelectrode produced similar results as lowering the actual microelectrode. However, applying a small puff of artificial cerebral spinal fluid was not sufficient to evoke adenosine. Multiple stimulations within a 50-μm region of a slice did not significantly change over time or damage cells. Chelating calcium with EDTA or blocking sodium channels with tetrodotoxin significantly decreased mechanically evoked adenosine, signifying that the release is activity dependent. An alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione, did not affect mechanically stimulated adenosine; however, the nucleoside triphosphate diphosphohydrolase 1,2 and 3 (NTDPase) inhibitor POM-1 significantly reduced adenosine so a portion of adenosine is dependent on extracellular ATP metabolism. Thus, mechanical perturbations from inserting a probe in the brain cause rapid, transient adenosine signaling which might be neuroprotective. We have discovered immediate changes in adenosine concentration in the prefrontal cortex following mechanical stimulation. The adenosine increase lasts only about 20 s. Mechanically stimulated adenosine was activity dependent and mostly because of extracellular ATP metabolism. This rapid, transient increase in adenosine may help protect tissue and would occur during implantation of any electrode, such as during deep brain stimulation.
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Affiliation(s)
| | | | | | - B. Jill Venton
- corresponding author Dept. of Chemistry University of Virginia Charlottesville, VA 22904 (434) 243-2132
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Dos Santos-Rodrigues A, Grañé-Boladeras N, Bicket A, Coe IR. Nucleoside transporters in the purinome. Neurochem Int 2014; 73:229-37. [PMID: 24704797 DOI: 10.1016/j.neuint.2014.03.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 03/23/2014] [Accepted: 03/24/2014] [Indexed: 01/20/2023]
Abstract
The purinome is a rich complex of proteins and cofactors that are involved in fundamental aspects of cellular homeostasis and cellular responses. The purinome is evolutionarily ancient and is made up of thousands of members. Our understanding of the mechanisms linking some parts of this complex network and the physiological relevance of the various connections is well advanced. However, our understanding of other parts of the purinome is less well developed. Our research focuses on the adenosine or nucleoside transporters (NTs), which are members of the membrane purinome. Nucleoside transporters are integral membrane proteins that are responsible for the flux of nucleosides, such as adenosine, and nucleoside analog drugs, used in a variety of anti-cancer, anti-viral and anti-parasite therapies, across cell membranes. Nucleoside transporters form the SLC28 and SLC29 families of solute carriers and the protein members of these families are widely distributed in human tissues including the central nervous system (CNS). NTs modulate purinergic signaling in the CNS primarily through their effects on modulating prevailing adenosine levels inside and outside the cell. By clearing the extracellular milieu of adenosine, NTs can terminate adenosine receptor-dependent signaling and this raises the possibility of regulatory feedback loops that tie together receptor signaling with transporter function. Despite the important role of NTs as modulators of purinergic signaling in the human body, very little is known about the nature or underlying mechanisms of regulation of either the SLC28 or SLC29 families, particularly within the context of the CNS purinome. Here we provide a brief overview of our current understanding of the regulation of members of the SLC29 family and highlight some interesting avenues for future research.
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Affiliation(s)
| | - Natalia Grañé-Boladeras
- Department of Chemistry and Biology, Faculty of Science, Ryerson University, Toronto, ON, Canada
| | - Alex Bicket
- Department of Biology, Faculty of Science, York University, Toronto, ON, Canada
| | - Imogen R Coe
- Department of Biology, Faculty of Science, York University, Toronto, ON, Canada; Department of Chemistry and Biology, Faculty of Science, Ryerson University, Toronto, ON, Canada.
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Sims RE, Dale N. Activity-dependent adenosine release may be linked to activation of Na(+)-K(+) ATPase: an in vitro rat study. PLoS One 2014; 9:e87481. [PMID: 24489921 PMCID: PMC3906196 DOI: 10.1371/journal.pone.0087481] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 12/23/2013] [Indexed: 01/06/2023] Open
Abstract
In the brain, extracellular adenosine increases as a result of neuronal activity. The mechanisms by which this occurs are only incompletely understood. Here we investigate the hypothesis that the Na+ influxes associated with neuronal signalling activate the Na+-K+ ATPase which, by consuming ATP, generates intracellular adenosine that is then released via transporters. By measuring adenosine release directly with microelectrode biosensors, we have demonstrated that AMPA-receptor evoked adenosine release in basal forebrain and cortex depends on extracellular Na+. We have simultaneously imaged intracellular Na+ and measured adenosine release. The accumulation of intracellular Na+ during AMPA receptor activation preceded adenosine release by some 90 s. By removing extracellular Ca2+, and thus preventing indiscriminate neuronal activation, we used ouabain to test the role of the Na+-K+ ATPase in the release of adenosine. Under conditions which caused a Na+ influx, brief applications of ouabain increased the accumulation of intracellular Na+ but conversely rapidly reduced extracellular adenosine levels. In addition, ouabain greatly reduced the amount of adenosine released during application of AMPA. Our data therefore suggest that activity of the Na+-K+ ATPase is directly linked to the efflux of adenosine and could provide a universal mechanism that couples adenosine release to neuronal activity. The Na+-K+ ATPase-dependent adenosine efflux is likely to provide adenosine-mediated activity-dependent negative feedback that will be important in many diverse functional contexts including the regulation of sleep.
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Affiliation(s)
- Robert Edward Sims
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
- * E-mail:
| | - Nicholas Dale
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
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Functional cooperation of metabotropic adenosine and glutamate receptors regulates postsynaptic plasticity in the cerebellum. J Neurosci 2014; 33:18661-71. [PMID: 24259587 DOI: 10.1523/jneurosci.5567-12.2013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
G-protein-coupled receptors (GPCRs) may form heteromeric complexes and cooperatively mediate cellular responses. Although heteromeric GPCR complexes are suggested to occur in many neurons, their contribution to neuronal function remains unclear. We address this question using two GPCRs expressed in cerebellar Purkinje cells: adenosine A1 receptor (A1R), which regulates neurotransmitter release and neuronal excitability in central neurons, and type-1 metabotropic glutamate receptor (mGluR1), which mediates cerebellar long-term depression, a form of synaptic plasticity crucial for cerebellar motor learning. We examined interaction between these GPCRs by immunocytochemical, biochemical, and Förster resonance energy transfer analyses in cultured mouse Purkinje cells and heterologous expression cells. These analyses revealed that the GPCRs closely colocalized and formed heteromeric complexes on the cell surfaces. Furthermore, our electrophysiological analysis showed that CSF levels (40-400 nm) of adenosine or synthetic A1R agonists with comparable potencies blocked mGluR1-mediated long-term depression of the postsynaptic glutamate-responsiveness (glu-LTD) of cultured Purkinje cells. A similar dose of the A1R agonist decreased the ligand affinity of mGluR1 and did not affect depolarization-induced Ca(2+) influx, which is an essential factor in inducing glu-LTD. The A1R agonist did not affect glu-LTD mimicked by direct activation of protein kinase C. These results suggest that A1R blocked glu-LTD by decreasing the ligand sensitivity of mGluR1, but not the coupling efficacy from mGluR1 to the intracellular signaling cascades. These findings provide a new insight into neuronal GPCR signaling and demonstrate a novel regulatory mechanism of synaptic plasticity.
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Gong CL, Leung YM, Wang MR, Lin NN, Lee TJF, Kuo JS. Neurochemicals involved in medullary control of common carotid blood flow. Curr Neuropharmacol 2014; 11:513-20. [PMID: 24403875 PMCID: PMC3763759 DOI: 10.2174/1570159x113119990044] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 01/22/2013] [Accepted: 07/17/2013] [Indexed: 11/22/2022] Open
Abstract
The common carotid artery (CCA) supplies intra- and extra-cranial vascular beds. An area in the medulla controlling CCA blood flow is defined as the dorsal facial area (DFA) by Kuo et al. in 1987. In the DFA, presynaptic nitrergic and/or glutamatergic fibers innervate preganglionic nitrergic and/or cholinergic neurons which give rise to the preganglionic fibers of the parasympathetic 7th and 9th cranial nerves. Released glutamate from presynaptic nitrergic and/or glutamatergic fibers can activate N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors on preganglionic nitrergic and/or cholinergic neurons. By modulating this glutamate release, several neurochemicals including serotonin, arginine, nitric oxide, nicotine, choline and ATP in the DFA regulate CCA blood flow. Understanding the neurochemical regulatory mechanisms can provide important insights of the physiological roles of the DFA, and may help develop therapeutic strategies for diseases involving CCA blood flow, such as migraine, hypertensive disease, Alzheimer’s disease and cerebral ischemic stroke.
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Affiliation(s)
- Chi-Li Gong
- Department of Physiology, School of Medicine, China Medical University, Taiwan
| | - Yuk-Man Leung
- Department of Physiology, School of Medicine, China Medical University, Taiwan; ; Graduate Institute of Neural and Cognitive Sciences, China Medical University, Taiwan
| | - Ming-Ren Wang
- Yuhing Junior College of Health Care and Management, Kaohsiung, Taiwan
| | - Nai-Nu Lin
- Department of Education and Research, Taichung Veterans General Hospital, Taichung, Taiwan
| | - Tony Jer-Fu Lee
- Neuro-Medical Scientific Center and Center for Vascular Medicine, Buddhist Tzu Chi General Hospital and Tzu Chi University, Hualien, Taiwan; ; Department of Medical Research, Buddhist Tzu Chi General Hospital and Tzu Chi University, Hualien, Taiwan
| | - Jon-Son Kuo
- Neuro-Medical Scientific Center and Center for Vascular Medicine, Buddhist Tzu Chi General Hospital and Tzu Chi University, Hualien, Taiwan; ; Department of Medical Research, Buddhist Tzu Chi General Hospital and Tzu Chi University, Hualien, Taiwan; ; Institute of Pharmacology and Toxicology, Tzu Chi University, Hualien, Taiwan
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Rodrigues TM, Jerónimo-Santos A, Sebastião AM, Diógenes MJ. Adenosine A(2A) Receptors as novel upstream regulators of BDNF-mediated attenuation of hippocampal Long-Term Depression (LTD). Neuropharmacology 2013; 79:389-98. [PMID: 24361450 DOI: 10.1016/j.neuropharm.2013.12.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 11/08/2013] [Accepted: 12/08/2013] [Indexed: 01/05/2023]
Abstract
Hippocampal Long-Term Potentiation (LTP) is facilitated by BDNF, through the activation of tropomyosin-related kinase B (TrkB) receptors. However, an influence of BDNF upon Long-Term Depression (LTD) was also shown. The present work aimed to further evaluate the effect of BDNF and TrkB receptors upon CA1 hippocampal LTD and to elucidate whether this effect is under the upstream control of other signalling processes, such as the adenosine A(2A)Receptors (A(2A)Rs). LTD, induced by a Low-Frequency Stimulation (LFS, 900 pulses, 1 Hz) in the CA1 area of rat hippocampal slices, was significantly attenuated when these slices were exposed to BDNF (60-100 ng/mL). A lower BDNF concentration (20 ng/ml) was only effective to inhibit LTD if A(2A)Rs were activated by a selective agonist, CGS 21680 (10 nM), or if the extracellular adenosine level was increased by 5-iodotubercidin (100 nM). BDNF (100 ng/ml) effect upon LTD was prevented by K252a (200 nM), which is known to prevent TrkB transphosphorylation, hence suggesting that this action requires TrkB receptor activation. BDNF (100 ng/ml) lacked effect on an adenosine-depleted background (adenosine deaminase, 2 U/ml) or under selective A(2A)R blockade (SCH 58261, 100 nM), indicating that it relies on tonic A(2A)R activation. Forskolin (10 μM), a cell-permeable activator of adenylate cyclase, rescued BDNF (100 ng/ml) effect in slices where A(2A)Rs were blocked with SCH 58261 (100 nM), whereas a PKA inhibitor, H-89 (1 μM), prevented LTD attenuation by BDNF (100 ng/ml). We conclude that the influence of BDNF TrkB receptors upon LTD is under the strict control of A(2A)Rs activation, through a mechanism that requires the cAMP/PKA transducing system.
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Affiliation(s)
- Tiago M Rodrigues
- Institute of Pharmacology and Neurosciences, Faculty of Medicine, University of Lisbon, Lisbon, Portugal; Unit of Neurosciences, Institute of Molecular Medicine, University of Lisbon, Lisbon, Portugal
| | - André Jerónimo-Santos
- Institute of Pharmacology and Neurosciences, Faculty of Medicine, University of Lisbon, Lisbon, Portugal; Unit of Neurosciences, Institute of Molecular Medicine, University of Lisbon, Lisbon, Portugal
| | - Ana M Sebastião
- Institute of Pharmacology and Neurosciences, Faculty of Medicine, University of Lisbon, Lisbon, Portugal; Unit of Neurosciences, Institute of Molecular Medicine, University of Lisbon, Lisbon, Portugal
| | - Maria José Diógenes
- Institute of Pharmacology and Neurosciences, Faculty of Medicine, University of Lisbon, Lisbon, Portugal; Unit of Neurosciences, Institute of Molecular Medicine, University of Lisbon, Lisbon, Portugal.
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Wall MJ, Dale N. Neuronal transporter and astrocytic ATP exocytosis underlie activity-dependent adenosine release in the hippocampus. J Physiol 2013; 591:3853-71. [PMID: 23713028 DOI: 10.1113/jphysiol.2013.253450] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The neuromodulator adenosine plays an important role in many physiological and pathological processes within the mammalian CNS. However, the precise mechanisms of how the concentration of extracellular adenosine increases following neural activity remain contentious. Here we have used microelectrode biosensors to directly measure adenosine release induced by focal stimulation in stratum radiatum of area CA1 in mouse hippocampal slices. Adenosine release was both action potential and Ca²⁺ dependent and could be evoked with low stimulation frequencies and small numbers of stimuli. Adenosine release required the activation of ionotropic glutamate receptors and could be evoked by local application of glutamate receptor agonists. Approximately 40% of stimulated-adenosine release occurred by translocation of adenosine via equilibrative nucleoside transporters (ENTs). This component of release persisted in the presence of the gliotoxin fluoroacetate and thus results from the direct release of adenosine from neurons. A reduction of adenosine release in the presence of NTPDase blockers, in slices from CD73(-/-) and dn-SNARE mice, provides evidence that a component of adenosine release arises from the extracellular metabolism of ATP released from astrocytes. This component of release appeared to have slower kinetics than the direct ENT-mediated release of adenosine. These data suggest that activity-dependent adenosine release is surprisingly complex and, in the hippocampus, arises from at least two distinct mechanisms with different cellular sources.
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Affiliation(s)
- Mark J Wall
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK.
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Contribution of Postsynaptic GluD2 to Presynaptic R-type Ca2+ Channel Function, Glutamate Release and Long-term Potentiation at Parallel Fiber to Purkinje Cell Synapses. THE CEREBELLUM 2013; 12:657-66. [DOI: 10.1007/s12311-013-0474-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Purinergic mechanisms and pain--an update. Eur J Pharmacol 2013; 716:24-40. [PMID: 23524093 DOI: 10.1016/j.ejphar.2013.01.078] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 12/11/2012] [Accepted: 01/09/2013] [Indexed: 12/12/2022]
Abstract
There is a brief summary of the background literature about purinergic signalling. The review then considers purinergic mechanosensory transduction involved in visceral, cutaneous and musculoskeletal nociception and on the roles played by P2X3, P2X2/3, P2X4, P2X7 and P2Y₁₂ receptors in neuropathic and inflammatory pain. Current developments of compounds for the therapeutic treatment of both visceral and neuropathic pain are discussed.
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Heinrich A, Andó RD, Túri G, Rózsa B, Sperlágh B. K+ depolarization evokes ATP, adenosine and glutamate release from glia in rat hippocampus: a microelectrode biosensor study. Br J Pharmacol 2013; 167:1003-20. [PMID: 22394324 DOI: 10.1111/j.1476-5381.2012.01932.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND AND PURPOSE This study was undertaken to characterize the ATP, adenosine and glutamate outflow evoked by depolarization with high K(+) concentrations, in slices of rat hippocampus. EXPERIMENTAL APPROACH We utilized the microelectrode biosensor technique and extracellular electrophysiological recording for the real-time monitoring of the efflux of ATP, adenosine and glutamate. KEY RESULTS ATP, adenosine and glutamate sensors exhibited transient and reversible current during depolarization with 25 mM K(+) , with distinct kinetics. The ecto-ATPase inhibitor ARL67156 enhanced the extracellular level of ATP and inhibited the prolonged adenosine efflux, suggesting that generation of adenosine may derive from the extracellular breakdown of ATP. Stimulation-evoked ATP, adenosine and glutamate efflux was inhibited by tetrodotoxin, while exposure to Ca(2+) -free medium abolished ATP and adenosine efflux from hippocampal slices. Extracellular elevation of ATP and adenosine were decreased in the presence of NMDA receptor antagonists, D-AP-5 and ifenprodil, whereas non-NMDA receptor blockade by CNQX inhibited glutamate but not ATP and adenosine efflux. The gliotoxin fluoroacetate and P2X7 receptor antagonists inhibited the K(+) -evoked ATP, adenosine and glutamate efflux, while carbenoxolone in low concentration and probenecid decreased only the adenosine efflux. CONCLUSIONS AND IMPLICATIONS Our results demonstrated activity-dependent gliotransmitter release in the hippocampus in response to ongoing neuronal activity. ATP and glutamate were released by P2X7 receptor activation into extracellular space. Although the increased extracellular levels of adenosine did derive from released ATP, adenosine might also be released directly via pannexin hemichannels.
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Affiliation(s)
- A Heinrich
- Laboratory of Molecular Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary Femtonics Ltd, Budapest, Hungary
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Dias RB, Rombo DM, Ribeiro JA, Henley JM, Sebastião AM. Adenosine: setting the stage for plasticity. Trends Neurosci 2013; 36:248-57. [PMID: 23332692 DOI: 10.1016/j.tins.2012.12.003] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 10/09/2012] [Accepted: 12/14/2012] [Indexed: 12/19/2022]
Abstract
It is widely accepted that Hebbian forms of plasticity mediate selective modifications in synaptic strength underlying information encoding in response to experience and circuit formation or refinement throughout development. Several complementary forms of homeostatic plasticity coordinate to keep Hebbian plasticity in check, frequently through the actions of conserved regulatory molecules. Recent evidence suggests that this may be the case for adenosine, which is ubiquitous in the brain and is released by both neurons and glial cells via constitutive and activity-dependent mechanisms. Through A1 and A2A receptor activation, adenosine modulates neuronal homeostasis and tunes the ability of synapses to undergo and/or sustain plasticity. Here, we review how adenosine equilibrates neuronal activity and sets the stage for synaptic plasticity.
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Affiliation(s)
- Raquel B Dias
- Institute of Pharmacology and Neurosciences, Faculty of Medicine, University of Lisbon, Lisbon, Portugal
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Sims RE, Wu HHT, Dale N. Sleep-wake sensitive mechanisms of adenosine release in the basal forebrain of rodents: an in vitro study. PLoS One 2013; 8:e53814. [PMID: 23326515 PMCID: PMC3543262 DOI: 10.1371/journal.pone.0053814] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 12/05/2012] [Indexed: 12/24/2022] Open
Abstract
Adenosine acting in the basal forebrain is a key mediator of sleep homeostasis. Extracellular adenosine concentrations increase during wakefulness, especially during prolonged wakefulness and lead to increased sleep pressure and subsequent rebound sleep. The release of endogenous adenosine during the sleep-wake cycle has mainly been studied in vivo with microdialysis techniques. The biochemical changes that accompany sleep-wake status may be preserved in vitro. We have therefore used adenosine-sensitive biosensors in slices of the basal forebrain (BFB) to study both depolarization-evoked adenosine release and the steady state adenosine tone in rats, mice and hamsters. Adenosine release was evoked by high K+, AMPA, NMDA and mGlu receptor agonists, but not by other transmitters associated with wakefulness such as orexin, histamine or neurotensin. Evoked and basal adenosine release in the BFB in vitro exhibited three key features: the magnitude of each varied systematically with the diurnal time at which the animal was sacrificed; sleep deprivation prior to sacrifice greatly increased both evoked adenosine release and the basal tone; and the enhancement of evoked adenosine release and basal tone resulting from sleep deprivation was reversed by the inducible nitric oxide synthase (iNOS) inhibitor, 1400 W. These data indicate that characteristics of adenosine release recorded in the BFB in vitro reflect those that have been linked in vivo to the homeostatic control of sleep. Our results provide methodologically independent support for a key role for induction of iNOS as a trigger for enhanced adenosine release following sleep deprivation and suggest that this induction may constitute a biochemical memory of this state.
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Affiliation(s)
- Robert Edward Sims
- School of Life Sciences, University of Warwick, Coventry, West Midlands, United Kingdom.
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Introduction to Purinergic Signalling in the Brain. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 986:1-12. [DOI: 10.1007/978-94-007-4719-7_1] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Pajski ML, Venton BJ. The mechanism of electrically stimulated adenosine release varies by brain region. Purinergic Signal 2012. [PMID: 23192278 DOI: 10.1007/s11302-012-9343-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Adenosine plays an important role in neuromodulation and neuroprotection. Recent identification of transient changes in adenosine concentration suggests adenosine may have a rapid modulatory role; however, the extent of these changes throughout the brain is not well understood. In this report, transient changes in adenosine evoked by one second, 60 Hz electrical stimulation trains were compared in the caudate-putamen, nucleus accumbens, hippocampus, and cortex. The concentration of evoked adenosine varies between brain regions, but there is less variation in the duration of signaling. The highest concentration of adenosine was evoked in the dorsal caudate-putamen (0.34 ± 0.08 μM), while the lowest concentration was in the secondary motor cortex (0.06 ± 0.02 μM). In all brain regions, adenosine release was activity-dependent. In the nucleus accumbens, hippocampus, and prefrontal cortex, this release was partly due to extracellular ATP breakdown. However, in the caudate-putamen, release was not due to ATP metabolism but was ionotropic glutamate receptor-dependent. The results demonstrate that transient, activity-dependent adenosine can be evoked in many brain regions but that the mechanism of formation and release varies by region.
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Affiliation(s)
- Megan L Pajski
- Chemistry Department, University of Virginia, Charlottesville, VA 22904, USA
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Deletion of ecto-5'-nucleotidase (CD73) reveals direct action potential-dependent adenosine release. J Neurosci 2012; 32:3842-7. [PMID: 22423104 DOI: 10.1523/jneurosci.6052-11.2012] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Purinergic signaling is a highly complex system of extracellular communication involved in many physiological and pathological functions in the mammalian brain. Its complexity stems from the multitude of purine receptor subtypes and endogenous purine receptor ligands (including ATP, ADP, UTP, UDP, and adenosine). Potentially all of these ligands could be directly released, and some could also arise from extracellular metabolism. A widely held consensus is that, except under pathological conditions, extracellular adenosine arises only from ectoATPase-mediated metabolism of previously released ATP. Here, we have used mice that lack the CD73 gene (encoding ecto-5'-nucleotidase that converts AMP to adenosine) to test whether action potential-dependent adenosine release in the cerebellum depends on prior ATP release. Surprisingly, we have uncovered two parallel pathways of adenosine release: one that is indirect via glutamate receptor-dependent release of ATP and a second of equal amplitude that has no dependence on prior release of ATP and thus represents the direct release of adenosine. This component of adenosine release is blocked by bafilomycin and modulated by mGlu4 receptor activation, strongly supporting adenosine release by exocytosis from parallel fibers. Our findings are a major step in understanding the mechanisms of adenosine release and are likely to have implications for all aspects of physiology where adenosine plays a key modulatory role.
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Soylu H, Zhang D, Buist R, Martin M, Albensi BC, Parkinson FE. Intracortical injection of endothelin-1 induces cortical infarcts in mice: effect of neuronal expression of an adenosine transporter. EXPERIMENTAL & TRANSLATIONAL STROKE MEDICINE 2012; 4:4. [PMID: 22409811 PMCID: PMC3329638 DOI: 10.1186/2040-7378-4-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 03/12/2012] [Indexed: 01/01/2023]
Abstract
Background Activation of adenosine A1 receptors has neuroprotective effects in animal stroke models. Adenosine levels are regulated by nucleoside transporters. In vitro studies showed that neuron-specific expression of human equilibrative nucleoside transporter 1 (hENT1) decreases extracellular adenosine levels and adenosine A1 receptor activity. In this study, we tested the effect of hENT1 expression on cortical infarct size following intracerebral injection of the vasoconstrictor endothelin-1 (ET-1) or saline. Methods Mice underwent stereotaxic intracortical injection of ET-1 (1 μl; 400 pmol) or saline (1 μl). Some mice received the adenosine receptor antagonist caffeine (25 mg/kg, intraperitoneal) 30 minutes prior to ET-1. Perfusion and T2-weighted magnetic resonance imaging (MRI) were used to measure cerebral blood flow (CBF) and subsequent infarct size, respectively. Results ET-1 reduced CBF at the injection site to 7.3 ± 1.3% (n = 12) in hENT1 transgenic (Tg) and 12.5 ± 2.0% (n = 13) in wild type (Wt) mice. At 48 hours following ET-1 injection, CBF was partially restored to 35.8 ± 4.5% in Tg and to 45.2 ± 6.3% in Wt mice; infarct sizes were significantly greater in Tg (9 ± 1.1 mm3) than Wt (5.4 ± 0.8 mm3) mice. Saline-treated Tg and Wt mice had modest decreases in CBF and infarcts were less than 1 mm3. For mice treated with caffeine, CBF values and infarct sizes were not significantly different between Tg and Wt mice. Conclusions ET-1 produced greater ischemic injury in hENT1 Tg than in Wt mice. This genotype difference was not observed in mice that had received caffeine. These data indicate that hENT1 Tg mice have reduced ischemia-evoked increases in adenosine receptor activity compared to Wt mice.
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Affiliation(s)
- Hanifi Soylu
- Departments of Pharmacology and Therapeutics, University of Manitoba, A404, 753 McDermot Avenue, Winnipeg, MB, Canada R3E 0 T6
| | - Dali Zhang
- Departments of Pharmacology and Therapeutics, University of Manitoba, A404, 753 McDermot Avenue, Winnipeg, MB, Canada R3E 0 T6
| | - Richard Buist
- Departments of Radiology, University of Manitoba, Winnipeg, Canada
| | - Melanie Martin
- Departments of Pharmacology and Therapeutics, University of Manitoba, A404, 753 McDermot Avenue, Winnipeg, MB, Canada R3E 0 T6.,Departments of Radiology, University of Manitoba, Winnipeg, Canada.,Department of Physics, University of Winnipeg, Winnipeg, Canada
| | - Benedict C Albensi
- Departments of Pharmacology and Therapeutics, University of Manitoba, A404, 753 McDermot Avenue, Winnipeg, MB, Canada R3E 0 T6.,Division of Neurodegenerative Disorders, St Boniface Hospital Research Centre, Winnipeg, MB, Canada
| | - Fiona E Parkinson
- Departments of Pharmacology and Therapeutics, University of Manitoba, A404, 753 McDermot Avenue, Winnipeg, MB, Canada R3E 0 T6
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Measurement of purine release with microelectrode biosensors. Purinergic Signal 2011; 8:27-40. [PMID: 22095158 DOI: 10.1007/s11302-011-9273-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 09/19/2011] [Indexed: 12/22/2022] Open
Abstract
Purinergic signalling departs from traditional paradigms of neurotransmission in the variety of release mechanisms and routes of production of extracellular ATP and adenosine. Direct real-time measurements of these purinergic agents have been of great value in understanding the functional roles of this signalling system in a number of diverse contexts. Here, we review the methods for measuring purine release, introduce the concept of microelectrode biosensors for ATP and adenosine and explain how these have been used to provide new mechanistic insight in respiratory chemoreception, synaptic physiology, eye development and purine salvage. We finish by considering the association of purine release with pathological conditions and examine the possibilities that biosensors for purines may one day be a standard part of the clinical diagnostic tool chest.
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Xia JX, Xiong JX, Wang HK, Duan SM, Ye JN, Hu ZA. Presynaptic inhibition of GABAergic synaptic transmission by adenosine in mouse hypothalamic hypocretin neurons. Neuroscience 2011; 201:46-56. [PMID: 22119641 DOI: 10.1016/j.neuroscience.2011.11.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 11/08/2011] [Accepted: 11/08/2011] [Indexed: 10/15/2022]
Abstract
Hypocretin neurons in the lateral hypothalamus, a new wakefulness-promoting center, have been recently regarded as an important target involved in endogenous adenosine-regulating sleep homeostasis. The GABAergic synaptic transmissions are the main inhibitory afferents to hypocretin neurons, which play an important role in the regulation of excitability of these neurons. The inhibitory effect of adenosine, a homeostatic sleep-promoting factor, on the excitatory glutamatergic synaptic transmissions in hypocretin neurons has been well documented, whether adenosine also modulates these inhibitory GABAergic synaptic transmissions in these neurons has not been investigated. In this study, the effect of adenosine on inhibitory postsynaptic currents (IPSCs) in hypocretin neurons was examined by using perforated patch-clamp recordings in the acute hypothalamic slices. The findings demonstrated that adenosine suppressed the amplitude of evoked IPSCs in a dose-dependent manner, which was completely abolished by 8-cyclopentyltheophylline (CPT), a selective antagonist of adenosine A1 receptor but not adenosine A2 receptor antagonist 3,7-dimethyl-1-(2-propynyl) xanthine. A presynaptic origin was suggested as following: adenosine increased paired-pulse ratio as well as reduced GABAergic miniature IPSC frequency without affecting the miniature IPSC amplitude. Further findings demonstrated that when the frequency of electrical stimulation was raised to 10 Hz, but not 1 Hz, a time-dependent depression of evoked IPSC amplitude was detected in hypocretin neurons, which could be partially blocked by CPT. However, under a higher frequency at 100 Hz stimulation, CPT had no action on the depressed GABAergic synaptic transmission induced by such tetanic stimulation in these hypocretin neurons. These results suggest that endogenous adenosine generated under certain stronger activities of synaptic transmissions exerts an inhibitory effect on GABAergic synaptic transmission in hypocretin neurons by activation of presynaptic adenosine A1 receptors, which may finely regulate the excitability of these neurons as well as eventually modulate the sleep-wakefulness.
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Affiliation(s)
- J X Xia
- Department of Physiology, Third Military Medical University, 30 Gaotanyan Street, Chongqing, 400038, China
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Klyuch BP, Dale N, Wall MJ. Receptor-mediated modulation of activity-dependent adenosine release in rat cerebellum. Neuropharmacology 2011; 62:815-24. [PMID: 21933676 DOI: 10.1016/j.neuropharm.2011.09.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Revised: 08/16/2011] [Accepted: 09/06/2011] [Indexed: 12/17/2022]
Abstract
Although the neuromodulator adenosine plays an important role in many central nervous system physiological and pathological processes, the properties and mechanisms of extracellular adenosine production are still unclear. In previous work, we determined that two forms of adenosine release can be evoked in the molecular layer of the cerebellum: one independent of ionotropic glutamate receptor activation (evoked by a train of stimuli) and one mainly dependent on the activation of ionotropic glutamate receptors (evoked by a single stimulus in 4-aminopyridine). Here we have investigated how these different forms of adenosine release are modulated by metabotropic receptors (A(1), GABA(B) and mGlu4). Although both types of adenosine release are inhibited by the activation of metabotropic receptors, single stimulus-evoked release was much more potently inhibited suggesting differential coupling between receptors and adenosine release mechanisms. Metabotropic receptor antagonists revealed that endogenous A(1) receptor activation plays the major role in controlling adenosine release and determine the relationship between stimulus strength and adenosine release. The major mechanism of modulation is through control of ionotropic glutamate receptor activation with block of metabotropic receptors inducing glutamate receptor-dependent adenosine release. In contrast to metabotropic receptor agonists, which inhibit adenylyl cyclase, activation of adenylyl cyclase (with forskolin) increased both glutamate receptor-dependent and independent adenosine release. This is the first time that the control of adenosine release by endogenous modulators has been studied and like classical neurotransmitters, adenosine release is controlled by an interplay of presynaptic modulators. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'.
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Affiliation(s)
- Boris P Klyuch
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
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Burnstock G, Krügel U, Abbracchio MP, Illes P. Purinergic signalling: from normal behaviour to pathological brain function. Prog Neurobiol 2011; 95:229-74. [PMID: 21907261 DOI: 10.1016/j.pneurobio.2011.08.006] [Citation(s) in RCA: 314] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 08/12/2011] [Accepted: 08/15/2011] [Indexed: 02/07/2023]
Abstract
Purinergic neurotransmission, involving release of ATP as an efferent neurotransmitter was first proposed in 1972. Later, ATP was recognised as a cotransmitter in peripheral nerves and more recently as a cotransmitter with glutamate, noradrenaline, GABA, acetylcholine and dopamine in the CNS. Both ATP, together with some of its enzymatic breakdown products (ADP and adenosine) and uracil nucleotides are now recognised to act via P2X ion channels and P1 and P2Y G protein-coupled receptors, which are widely expressed in the brain. They mediate both fast signalling in neurotransmission and neuromodulation and long-term (trophic) signalling in cell proliferation, differentiation and death. Purinergic signalling is prominent in neurone-glial cell interactions. In this review we discuss first the evidence implicating purinergic signalling in normal behaviour, including learning and memory, sleep and arousal, locomotor activity and exploration, feeding behaviour and mood and motivation. Then we turn to the involvement of P1 and P2 receptors in pathological brain function; firstly in trauma, ischemia and stroke, then in neurodegenerative diseases, including Alzheimer's, Parkinson's and Huntington's, as well as multiple sclerosis and amyotrophic lateral sclerosis. Finally, the role of purinergic signalling in neuropsychiatric diseases (including schizophrenia), epilepsy, migraine, cognitive impairment and neuropathic pain will be considered.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London NW3 2PF, UK.
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A population of immature cerebellar parallel fibre synapses are insensitive to adenosine but are inhibited by hypoxia. Neuropharmacology 2011; 61:880-8. [PMID: 21693125 DOI: 10.1016/j.neuropharm.2011.06.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Revised: 03/09/2011] [Accepted: 06/06/2011] [Indexed: 12/20/2022]
Abstract
The purine adenosine plays an important role in a number of physiological and pathological processes and is neuroprotective during hypoxia and ischemia. The major effect of adenosine is to suppress network activity via the activation of A(1) receptors. Here we report that in immature cerebellar slices, the activation of A(1) receptors has variable effects on parallel fibre synaptic transmission, ranging from zero depression to an almost complete abolition of transmission. Concentration-response curves suggest that the heterogeneity of inhibition stems from differences in A(1) receptor properties which could include coupling to downstream effectors. There is less variation in the effects of adenosine at parallel fibre synapses in slices from older rats and thus adenosine signalling appears developmentally regulated. In the cerebellum, hypoxia increases the concentration of extracellular adenosine leading to the activation of A(1) receptors (at adenosine-sensitive parallel fibre synapses) and the suppression of glutamate release. It would be predicted that the synapses that were insensitive to adenosine would be less depressed by hypoxia and thus maintain function during metabolic stress. However those synapses which were insensitive to adenosine were rapidly inhibited by hypoxia via a mechanism which was not reversed by blocking A(1) receptors. Thus another mechanism must be responsible for the hypoxia-mediated depression at these synapses. These different mechanisms of depression may be important for cell survival and for maintenance of cerebellar function following oxygen starvation.
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Koos BJ. Adenosine A₂a receptors and O₂ sensing in development. Am J Physiol Regul Integr Comp Physiol 2011; 301:R601-22. [PMID: 21677265 DOI: 10.1152/ajpregu.00664.2010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Reduced mitochondrial oxidative phosphorylation, via activation of adenylate kinase and the resulting exponential rise in the cellular AMP/ATP ratio, appears to be a critical factor underlying O₂ sensing in many chemoreceptive tissues in mammals. The elevated AMP/ATP ratio, in turn, activates key enzymes that are involved in physiologic adjustments that tend to balance ATP supply and demand. An example is the conversion of AMP to adenosine via 5'-nucleotidase and the resulting activation of adenosine A(₂A) receptors, which are involved in acute oxygen sensing by both carotid bodies and the brain. In fetal sheep, A(₂A) receptors associated with carotid bodies trigger hypoxic cardiovascular chemoreflexes, while central A(₂A) receptors mediate hypoxic inhibition of breathing and rapid eye movements. A(₂A) receptors are also involved in hypoxic regulation of fetal endocrine systems, metabolism, and vascular tone. In developing lambs, A(₂A) receptors play virtually no role in O₂ sensing by the carotid bodies, but brain A(₂A) receptors remain critically involved in the roll-off ventilatory response to hypoxia. In adult mammals, A(₂A) receptors have been implicated in O₂ sensing by carotid glomus cells, while central A(₂A) receptors likely blunt hypoxic hyperventilation. In conclusion, A(₂A) receptors are crucially involved in the transduction mechanisms of O₂ sensing in fetal carotid bodies and brains. Postnatally, central A(₂A) receptors remain key mediators of hypoxic respiratory depression, but they are less critical for O₂ sensing in carotid chemoreceptors, particularly in developing lambs.
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Affiliation(s)
- Brian J Koos
- Department of Obstetrics and Gynecology; Brain Research Institute, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, USA.
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Klyuch BP, Richardson MJE, Dale N, Wall MJ. The dynamics of single spike-evoked adenosine release in the cerebellum. J Physiol 2010; 589:283-95. [PMID: 21078589 DOI: 10.1113/jphysiol.2010.198986] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The purine adenosine is a potent neuromodulator in the brain, with roles in a number of diverse physiological and pathological processes. Modulators such as adenosine are difficult to study as once released they have a diffuse action (which can affect many neurones) and, unlike classical neurotransmitters, have no inotropic receptors. Thus rapid postsynaptic currents (PSCs) mediated by adenosine (equivalent to mPSCs) are not available for study. As a result the mechanisms and properties of adenosine release still remain relatively unclear. We have studied adenosine release evoked by stimulating the parallel fibres in the cerebellum. Using adenosine biosensors combined with deconvolution analysis and mathematical modelling, we have characterised the release dynamics and diffusion of adenosine in unprecedented detail. By partially blocking K+ channels, we were able to release adenosine in response to a single stimulus rather than a train of stimuli. This allowed reliable sub-second release of reproducible quantities of adenosine with stereotypic concentration waveforms that agreed well with predictions of a mathematical model of purine diffusion. We found no evidence for ATP release and thus suggest that adenosine is directly released in response to parallel fibre firing and does not arise from extracellular ATP metabolism. Adenosine release events showed novel short-term dynamics, including facilitated release with paired stimuli at millisecond stimulation intervals but depletion-recovery dynamics with paired stimuli delivered over minute time scales. These results demonstrate rich dynamics for adenosine release that are placed, for the first time, on a quantitative footing and show strong similarity with vesicular exocytosis.
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Affiliation(s)
- Boris P Klyuch
- Department of Biological Sciences, University of Warwick, Coventry, UK
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Yamamoto K, Noguchi J, Yamada C, Watabe AM, Kato F. Distinct target cell-dependent forms of short-term plasticity of the central visceral afferent synapses of the rat. BMC Neurosci 2010; 11:134. [PMID: 20961403 PMCID: PMC2978217 DOI: 10.1186/1471-2202-11-134] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Accepted: 10/20/2010] [Indexed: 11/25/2022] Open
Abstract
Background The visceral afferents from various cervico-abdominal sensory receptors project to the dorsal vagal complex (DVC), which is composed of the nucleus of the solitary tract (NTS), the area postrema and the dorsal motor nucleus of the vagus nerve (DMX), via the vagus and glossopharyngeal nerves and then the solitary tract (TS) in the brainstem. While the excitatory transmission at the TS-NTS synapses shows strong frequency-dependent suppression in response to repeated stimulation of the afferents, the frequency dependence and short-term plasticity at the TS-DMX synapses, which also transmit monosynaptic information from the visceral afferents to the DVC neurons, remain largely unknown. Results Recording of the EPSCs activated by paired or repeated TS stimulation in the brainstem slices of rats revealed that, unlike NTS neurons whose paired-pulse ratio (PPR) is consistently below 0.6, the distribution of the PPR of DMX neurons shows bimodal peaks that are composed of type I (PPR, 0.6-1.5; 53% of 120 neurons recorded) and type II (PPR, < 0.6; 47%) neurons. Some of the type I DMX neurons showed paired-pulse potentiation. The distinction of these two types depended on the presynaptic release probability and the projection target of the postsynaptic cells; the distinction was not dependent on the location or soma size of the cell, intensity or site of the stimulation, the latency, standard deviation of latency or the quantal size. Repeated stimulation at 20 Hz resulted in gradual and potent decreases in EPSC amplitude in the NTS and type II DMX neurons, whereas type I DMX neurons displayed only slight decreases, which indicates that the DMX neurons of this type could be continuously activated by repeated firing of primary afferent fibers at a high (~10 Hz) frequency. Conclusions These two general types of short-term plasticity might contribute to the differential activation of distinct vago-vagal reflex circuits, depending on the firing frequency and type of visceral afferents.
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Affiliation(s)
- Kiyofumi Yamamoto
- Laboratory of Neurophysiology, Department of Neuroscience, Jikei University School of Medicine, Minato-ku, Tokyo 105-8461, Japan
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