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Juvenal G, Higa GSV, Bonfim Marques L, Tessari Zampieri T, Costa Viana FJ, Britto LR, Tang Y, Illes P, di Virgilio F, Ulrich H, de Pasquale R. Regulation of GABAergic neurotransmission by purinergic receptors in brain physiology and disease. Purinergic Signal 2024:10.1007/s11302-024-10034-x. [PMID: 39046648 DOI: 10.1007/s11302-024-10034-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 06/19/2024] [Indexed: 07/25/2024] Open
Abstract
Purinergic receptors regulate the processing of neural information in the hippocampus and cerebral cortex, structures related to cognitive functions. These receptors are activated when astrocytic and neuronal populations release adenosine triphosphate (ATP) in an autocrine and paracrine manner, following sustained patterns of neuronal activity. The modulation by these receptors of GABAergic transmission has only recently been studied. Through their ramifications, astrocytes and GABAergic interneurons reach large groups of excitatory pyramidal neurons. Their inhibitory effect establishes different synchronization patterns that determine gamma frequency rhythms, which characterize neural activities related to cognitive processes. During early life, GABAergic-mediated synchronization of excitatory signals directs the experience-driven maturation of cognitive development, and dysfunctions concerning this process have been associated with neurological and neuropsychiatric diseases. Purinergic receptors timely modulate GABAergic control over ongoing neural activity and deeply affect neural processing in the hippocampal and neocortical circuitry. Stimulation of A2 receptors increases GABA release from presynaptic terminals, leading to a considerable reduction in neuronal firing of pyramidal neurons. A1 receptors inhibit GABAergic activity but only act in the early postnatal period when GABA produces excitatory signals. P2X and P2Y receptors expressed in pyramidal neurons reduce the inhibitory tone by blocking GABAA receptors. Finally, P2Y receptor activation elicits depolarization of GABAergic neurons and increases GABA release, thus favoring the emergence of gamma oscillations. The present review provides an overall picture of purinergic influence on GABAergic transmission and its consequences on neural processing, extending the discussion to receptor subtypes and their involvement in the onset of brain disorders, including epilepsy and Alzheimer's disease.
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Affiliation(s)
- Guilherme Juvenal
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP, Brazil
| | - Guilherme Shigueto Vilar Higa
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP, Brazil
- Department of Biophysics and Physiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Lucas Bonfim Marques
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP, Brazil
| | - Thais Tessari Zampieri
- Department of Biophysics and Physiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Felipe José Costa Viana
- Department of Biophysics and Physiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Luiz R Britto
- Department of Biophysics and Physiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Yong Tang
- International Joint Research Centre On Purinergic Signalling, Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, China
- School of Health and Rehabilitation, Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, China
| | - Peter Illes
- International Joint Research Centre On Purinergic Signalling, Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, China
- School of Health and Rehabilitation, Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, China
- Rudolf Boehm Institute for Pharmacology and Toxicology, University of Leipzig, 04107, Leipzig, Germany
| | | | - Henning Ulrich
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP, Brazil.
- International Joint Research Centre On Purinergic Signalling, Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, China.
| | - Roberto de Pasquale
- Department of Biophysics and Physiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil.
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Kumaria A, Ashkan K. Novel therapeutic strategies in glioma targeting glutamatergic neurotransmission. Brain Res 2023; 1818:148515. [PMID: 37543066 DOI: 10.1016/j.brainres.2023.148515] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Revised: 07/11/2023] [Accepted: 07/30/2023] [Indexed: 08/07/2023]
Abstract
High grade gliomas carry a poor prognosis despite aggressive surgical and adjuvant approaches including chemoradiotherapy. Recent studies have demonstrated a mitogenic association between neuronal electrical activity and glioma growth involving the PI3K-mTOR pathway. As the predominant excitatory neurotransmitter of the brain, glutamate signalling in particular has been shown to promote glioma invasion and growth. The concept of the neurogliomal synapse has been established whereby glutamatergic receptors on glioma cells have been shown to promote tumour propagation. Targeting glutamatergic signalling is therefore a potential treatment option in glioma. Antiepileptic medications decrease excess neuronal electrical activity and some may possess anti-glutamate effects. Although antiepileptic medications continue to be investigated for an anti-glioma effect, good quality randomised trial evidence is lacking. Other pharmacological strategies that downregulate glutamatergic signalling include riluzole, memantine and anaesthetic agents. Neuromodulatory interventions possessing potential anti-glutamate activity include deep brain stimulation and vagus nerve stimulation - this contributes to the anti-seizure efficacy of the latter and the possible neuroprotective effect of the former. A possible role of neuromodulation as a novel anti-glioma modality has previously been proposed and that hypothesis is extended to include these modalities. Similarly, the significant survival benefit in glioblastoma attributable to alternating electrical fields (Tumour Treating Fields) may be a result of disruption to neurogliomal signalling. Further studies exploring excitatory neurotransmission and glutamatergic signalling and their role in glioma origin, growth and propagation are therefore warranted.
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Affiliation(s)
- Ashwin Kumaria
- Department of Neurosurgery, Queen's Medical Centre, Nottingham University Hospitals, Nottingham, UK.
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3
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Pieróg M, Socała K, Nieoczym D, Wyska E, Samorek-Pieróg M, Wlaź P. Anticonvulsant Profile of Selected Medium-Chain Fatty Acids (MCFAs) Co-Administered with Metformin in Mice in Acute and Chronic Treatment. Molecules 2023; 28:molecules28093810. [PMID: 37175220 PMCID: PMC10179922 DOI: 10.3390/molecules28093810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 04/22/2023] [Accepted: 04/27/2023] [Indexed: 05/15/2023] Open
Abstract
In contrast to the other components of the medium-chain triglycerides ketogenic diet (MCT KD), i.e., caprylic acid (CA8), a comprehensive evaluation of caproic (CA6) and lauric acids' (CA12) properties in standard chemical and electrical seizure tests in mice has not yet been performed. We investigated their effects in maximal electroshock seizure threshold (MEST), 6 Hz seizure threshold and intravenous (i.v.) pentylenetetrazole (PTZ) seizure tests. Since ketone body production can be regulated by the activation of 5'AMP-activated protein kinase (AMPK), we hypothesized that metformin (an AMPK activator) enhance ketogenesis and would act synergistically with the fatty acids to inhibit convulsions. We assessed the effects of acute and chronic co-treatment with metformin and CA6/CA8 on seizures. CA6 and CA12 (p.o.) increased seizure threshold in the 6 Hz seizure test. CA6 at the highest tested dose (30 mmol/kg) developed toxicity in several mice, impaired motor performance and induced ketoacidosis. Acute and chronic co-treatment with metformin and CA6/CA8 did not affect seizure thresholds. Moreover, we observed the pro-convulsive effect of the acute co-administration of CA8 (5 mmol/kg) and metformin (100 mg/kg). Since this co-treatment was pro-convulsive, the safety profile and risk/benefit ratio of MCT KD and metformin concomitant therapy in epileptic patients should be further evaluated.
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Affiliation(s)
- Mateusz Pieróg
- Department of Animal Physiology and Pharmacology, Institute of Biological Sciences, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland
| | - Katarzyna Socała
- Department of Animal Physiology and Pharmacology, Institute of Biological Sciences, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland
| | - Dorota Nieoczym
- Department of Animal Physiology and Pharmacology, Institute of Biological Sciences, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland
| | - Elżbieta Wyska
- Department of Pharmacokinetics and Physical Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688 Kraków, Poland
| | - Małgorzata Samorek-Pieróg
- Department of Parasitology and Invasive Diseases, National Veterinary Research Institute, Partyzantów Avenue 57, 24-100 Puławy, Poland
| | - Piotr Wlaź
- Department of Animal Physiology and Pharmacology, Institute of Biological Sciences, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland
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Lohr C. Role of P2Y receptors in astrocyte physiology and pathophysiology. Neuropharmacology 2023; 223:109311. [PMID: 36328064 DOI: 10.1016/j.neuropharm.2022.109311] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/24/2022] [Accepted: 10/27/2022] [Indexed: 11/07/2022]
Abstract
Astrocytes are active constituents of the brain that manage ion homeostasis and metabolic support of neurons and directly tune synaptic transmission and plasticity. Astrocytes express all known P2Y receptors. These regulate a multitude of physiological functions such as cell proliferation, Ca2+ signalling, gliotransmitter release and neurovascular coupling. In addition, P2Y receptors are fundamental in the transition of astrocytes into reactive astrocytes, as occurring in many brain disorders such as neurodegenerative diseases, neuroinflammation and epilepsy. This review summarizes the current literature addressing the function of P2Y receptors in astrocytes in the healthy brain as well as in brain diseases.
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Affiliation(s)
- Christian Lohr
- Institute of Cell and Systems Biology of Animals, University of Hamburg, Germany.
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Malchow RP, Tchernookova BK, Choi JIV, Smith PJS, Kramer RH, Kreitzer MA. Review and Hypothesis: A Potential Common Link Between Glial Cells, Calcium Changes, Modulation of Synaptic Transmission, Spreading Depression, Migraine, and Epilepsy-H . Front Cell Neurosci 2021; 15:693095. [PMID: 34539347 PMCID: PMC8446203 DOI: 10.3389/fncel.2021.693095] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 06/25/2021] [Indexed: 01/03/2023] Open
Abstract
There is significant evidence to support the notion that glial cells can modulate the strength of synaptic connections between nerve cells, and it has further been suggested that alterations in intracellular calcium are likely to play a key role in this process. However, the molecular mechanism(s) by which glial cells modulate neuronal signaling remains contentiously debated. Recent experiments have suggested that alterations in extracellular H+ efflux initiated by extracellular ATP may play a key role in the modulation of synaptic strength by radial glial cells in the retina and astrocytes throughout the brain. ATP-elicited alterations in H+ flux from radial glial cells were first detected from Müller cells enzymatically dissociated from the retina of tiger salamander using self-referencing H+-selective microelectrodes. The ATP-elicited alteration in H+ efflux was further found to be highly evolutionarily conserved, extending to Müller cells isolated from species as diverse as lamprey, skate, rat, mouse, monkey and human. More recently, self-referencing H+-selective electrodes have been used to detect ATP-elicited alterations in H+ efflux around individual mammalian astrocytes from the cortex and hippocampus. Tied to increases in intracellular calcium, these ATP-induced extracellular acidifications are well-positioned to be key mediators of synaptic modulation. In this article, we examine the evidence supporting H+ as a key modulator of neurotransmission, review data showing that extracellular ATP elicits an increase in H+ efflux from glial cells, and describe the potential signal transduction pathways involved in glial cell-mediated H+ efflux. We then examine the potential role that extracellular H+ released by glia might play in regulating synaptic transmission within the vertebrate retina, and then expand the focus to discuss potential roles in spreading depression, migraine, epilepsy, and alterations in brain rhythms, and suggest that alterations in extracellular H+ may be a unifying feature linking these disparate phenomena.
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Affiliation(s)
- Robert Paul Malchow
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, United States
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, United States
| | - Boriana K. Tchernookova
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, United States
| | - Ji-in Vivien Choi
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, United States
- Stritch School of Medicine, Loyola University, Maywood, IL, United States
| | - Peter J. S. Smith
- Institute for Life Sciences, University of Southampton, Highfield Campus, Southampton, United Kingdom
- Bell Center, Marine Biological Laboratory, Woods Hole, MA, United States
| | - Richard H. Kramer
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, United States
| | - Matthew A. Kreitzer
- Department of Biology, Indiana Wesleyan University, Marion, IN, United States
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Zaitsev АV, Amakhin DV, Dyomina AV, Zakharova MV, Ergina JL, Postnikova TY, Diespirov GP, Magazanik LG. Synaptic Dysfunction in Epilepsy. J EVOL BIOCHEM PHYS+ 2021. [DOI: 10.1134/s002209302103008x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Sharma S, Tiarks G, Haight J, Bassuk AG. Neuropathophysiological Mechanisms and Treatment Strategies for Post-traumatic Epilepsy. Front Mol Neurosci 2021; 14:612073. [PMID: 33708071 PMCID: PMC7940684 DOI: 10.3389/fnmol.2021.612073] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 01/26/2021] [Indexed: 12/11/2022] Open
Abstract
Traumatic brain injury (TBI) is a leading cause of death in young adults and a risk factor for acquired epilepsy. Severe TBI, after a period of time, causes numerous neuropsychiatric and neurodegenerative problems with varying comorbidities; and brain homeostasis may never be restored. As a consequence of disrupted equilibrium, neuropathological changes such as circuit remodeling, reorganization of neural networks, changes in structural and functional plasticity, predisposition to synchronized activity, and post-translational modification of synaptic proteins may begin to dominate the brain. These pathological changes, over the course of time, contribute to conditions like Alzheimer disease, dementia, anxiety disorders, and post-traumatic epilepsy (PTE). PTE is one of the most common, devastating complications of TBI; and of those affected by a severe TBI, more than 50% develop PTE. The etiopathology and mechanisms of PTE are either unknown or poorly understood, which makes treatment challenging. Although anti-epileptic drugs (AEDs) are used as preventive strategies to manage TBI, control acute seizures and prevent development of PTE, their efficacy in PTE remains controversial. In this review, we discuss novel mechanisms and risk factors underlying PTE. We also discuss dysfunctions of neurovascular unit, cell-specific neuroinflammatory mediators and immune response factors that are vital for epileptogenesis after TBI. Finally, we describe current and novel treatments and management strategies for preventing PTE.
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Affiliation(s)
- Shaunik Sharma
- Medical Laboratories, Department of Pediatrics, University of Iowa, Iowa City, IA, United States
| | - Grant Tiarks
- Medical Laboratories, Department of Pediatrics, University of Iowa, Iowa City, IA, United States
| | - Joseph Haight
- Medical Laboratories, Department of Pediatrics, University of Iowa, Iowa City, IA, United States
| | - Alexander G Bassuk
- Medical Laboratories, Department of Pediatrics, University of Iowa, Iowa City, IA, United States
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Verhoog QP, Holtman L, Aronica E, van Vliet EA. Astrocytes as Guardians of Neuronal Excitability: Mechanisms Underlying Epileptogenesis. Front Neurol 2020; 11:591690. [PMID: 33324329 PMCID: PMC7726323 DOI: 10.3389/fneur.2020.591690] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 10/26/2020] [Indexed: 12/11/2022] Open
Abstract
Astrocytes are key homeostatic regulators in the central nervous system and play important roles in physiology. After brain damage caused by e.g., status epilepticus, traumatic brain injury, or stroke, astrocytes may adopt a reactive phenotype. This process of reactive astrogliosis is important to restore brain homeostasis. However, persistent reactive astrogliosis can be detrimental for the brain and contributes to the development of epilepsy. In this review, we will focus on physiological functions of astrocytes in the normal brain as well as pathophysiological functions in the epileptogenic brain, with a focus on acquired epilepsy. We will discuss the role of astrocyte-related processes in epileptogenesis, including reactive astrogliosis, disturbances in energy supply and metabolism, gliotransmission, and extracellular ion concentrations, as well as blood-brain barrier dysfunction and dysregulation of blood flow. Since dysfunction of astrocytes can contribute to epilepsy, we will also discuss their role as potential targets for new therapeutic strategies.
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Affiliation(s)
- Quirijn P. Verhoog
- Leiden Academic Center for Drug Research, Leiden University, Leiden, Netherlands
- Department of Neuropathology, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Linda Holtman
- Leiden Academic Center for Drug Research, Leiden University, Leiden, Netherlands
| | - Eleonora Aronica
- Department of Neuropathology, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, Netherlands
| | - Erwin A. van Vliet
- Department of Neuropathology, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
- Center for Neuroscience, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, Netherlands
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Scemes E, Velíšek L, Velíšková J. Astrocyte and Neuronal Pannexin1 Contribute Distinctly to Seizures. ASN Neuro 2020; 11:1759091419833502. [PMID: 30862176 PMCID: PMC6415468 DOI: 10.1177/1759091419833502] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
ATP- and adenosine-mediated signaling are prominent types of glia–glia and glia–neuron interaction, with an imbalance of ATP/adenosine ratio leading to altered states of excitability, as seen in epileptic seizures. Pannexin1 (Panx1), a member of the gap junction family, is an ATP release channel that is expressed in astrocytes and neurons. Previous studies provided evidence supporting a role for purinergic-mediated signaling via Panx1 channels in seizures; using mice with global deletion of Panx1, it was shown that these channels contribute in maintenance of seizures by releasing ATP. However, nothing is known about the extent to which astrocyte and neuronal Panx1 might differently contribute to seizures. We here show that targeted deletion of Panx1 in astrocytes or neurons has opposing effects on acute seizures induced by kainic acid. The absence of Panx1 in astrocytes potentiates while the absence of Panx1 in neurons attenuates seizure manifestation. Immunohistochemical analysis performed in brains of these mice, revealed that adenosine kinase (ADK), an enzyme that regulates extracellular levels of adenosine, was increased only in seized GFAP-Cre:Panx1f/f mice. Pretreating mice with the ADK inhibitor, idotubercidin, improved seizure outcome and prevented the increase in ADK immunoreactivity. Together, these data suggest that the worsening of seizures seen in mice lacking astrocyte Panx1 is likely related to low levels of extracellular adenosine due to the increased ADK levels in astrocytes. Our study not only reveals an unexpected link between Panx1 channels and ADK but also highlights the important role played by astrocyte Panx1 channels in controlling neuronal activity.
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Affiliation(s)
- Eliana Scemes
- 1 Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, USA
| | - Libor Velíšek
- 1 Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, USA.,2 Departments of Neurology and Pediatrics, New York Medical College, Valhalla, NY, USA
| | - Jana Velíšková
- 1 Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, USA.,3 Departments of Obstetrics & Gynecology and Neurology, New York Medical College, Valhalla, NY, USA
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Illes P, Burnstock G, Tang Y. Astroglia-Derived ATP Modulates CNS Neuronal Circuits. Trends Neurosci 2019; 42:885-898. [PMID: 31704181 DOI: 10.1016/j.tins.2019.09.006] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 09/10/2019] [Accepted: 09/23/2019] [Indexed: 02/08/2023]
Abstract
It is broadly recognized that ATP not only supports energy storage within cells but is also a transmitter/signaling molecule that serves intercellular communication. Whereas the fast (co)transmitter function of ATP in the peripheral nervous system has been convincingly documented, in the central nervous system (CNS) ATP appears to be primarily a slow transmitter/modulator. Data discussed in the present review suggest that the slow modulatory effects of ATP arise as a result of its vesicular/nonvesicular release from astrocytes. ATP acts together with other glial signaling molecules such as cytokines, chemokines, and free radicals to modulate neuronal circuits. Hence, astrocytes are positioned at the crossroads of the neuron-glia-neuron communication pathway.
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Affiliation(s)
- Peter Illes
- Rudolf Boehm Institute for Pharmacology and Toxicology, University of Leipzig, 04107 Leipzig, Germany; Acupuncture and Tuina School, Chengdu University of Traditional Chinese Medicine (TCM), 610075 Chengdu, China.
| | - Geoffrey Burnstock
- Department of Pharmacology and Therapeutics, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Yong Tang
- Acupuncture and Tuina School, Chengdu University of Traditional Chinese Medicine (TCM), 610075 Chengdu, China
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11
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Morin-Brureau M, Milior G, Royer J, Chali F, Le Duigou C, Savary E, Blugeon C, Jourdren L, Akbar D, Dupont S, Navarro V, Baulac M, Bielle F, Mathon B, Clemenceau S, Miles R. Microglial phenotypes in the human epileptic temporal lobe. Brain 2019; 141:3343-3360. [PMID: 30462183 DOI: 10.1093/brain/awy276] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 09/12/2018] [Indexed: 12/11/2022] Open
Abstract
Microglia, the immune cells of the brain, are highly plastic and possess multiple functional phenotypes. Differences in phenotype in different regions and different states of epileptic human brain have been little studied. Here we use transcriptomics, anatomy, imaging of living cells and ELISA measurements of cytokine release to examine microglia from patients with temporal lobe epilepsies. Two distinct microglial phenotypes were explored. First we asked how microglial phenotype differs between regions of high and low neuronal loss in the same brain. Second, we asked how microglial phenotype is changed by a recent seizure. In sclerotic areas with few neurons, microglia have an amoeboid rather than ramified shape, express activation markers and respond faster to purinergic stimuli. The repairing interleukin, IL-10, regulates the basal phenotype of microglia in the CA1 and CA3 regions with neuronal loss and gliosis. To understand changes in phenotype induced by a seizure, we estimated the delay from the last seizure until tissue collection from changes in reads for immediate early gene transcripts. Pseudotime ordering of these data was validated by comparison with results from kainate-treated mice. It revealed a local and transient phenotype in which microglia secrete the human interleukin CXCL8, IL-1B and other cytokines. This secretory response is mediated in part via the NRLP3 inflammasome.
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Affiliation(s)
- Mélanie Morin-Brureau
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMR S1127, Institut du Cerveau et de la Moelle épinière, Paris, France
| | - Giampaolo Milior
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMR S1127, Institut du Cerveau et de la Moelle épinière, Paris, France
| | - Juliette Royer
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMR S1127, Institut du Cerveau et de la Moelle épinière, Paris, France
| | - Farah Chali
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMR S1127, Institut du Cerveau et de la Moelle épinière, Paris, France
| | - Caroline Le Duigou
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMR S1127, Institut du Cerveau et de la Moelle épinière, Paris, France
| | - Etienne Savary
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMR S1127, Institut du Cerveau et de la Moelle épinière, Paris, France
| | - Corinne Blugeon
- École normale supérieure, PSL Research University, CNRS, Inserm, Institut de Biologie de l'École normale supérieure (IBENS), Plateforme Génomique, Paris, France
| | - Laurent Jourdren
- École normale supérieure, PSL Research University, CNRS, Inserm, Institut de Biologie de l'École normale supérieure (IBENS), Plateforme Génomique, Paris, France
| | - David Akbar
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMR S1127, Institut du Cerveau et de la Moelle épinière, Paris, France
| | - Sophie Dupont
- AP-HP, GH Pitie-Salpêtrière-Charles Foix, Epilepsy Unit (VN, MB, SD), Neuropathologie (FB), Neurochirurgie (BM, SC), Paris, France
| | - Vincent Navarro
- AP-HP, GH Pitie-Salpêtrière-Charles Foix, Epilepsy Unit (VN, MB, SD), Neuropathologie (FB), Neurochirurgie (BM, SC), Paris, France
| | - Michel Baulac
- AP-HP, GH Pitie-Salpêtrière-Charles Foix, Epilepsy Unit (VN, MB, SD), Neuropathologie (FB), Neurochirurgie (BM, SC), Paris, France
| | - Franck Bielle
- AP-HP, GH Pitie-Salpêtrière-Charles Foix, Epilepsy Unit (VN, MB, SD), Neuropathologie (FB), Neurochirurgie (BM, SC), Paris, France
| | - Bertrand Mathon
- AP-HP, GH Pitie-Salpêtrière-Charles Foix, Epilepsy Unit (VN, MB, SD), Neuropathologie (FB), Neurochirurgie (BM, SC), Paris, France
| | - Stéphane Clemenceau
- AP-HP, GH Pitie-Salpêtrière-Charles Foix, Epilepsy Unit (VN, MB, SD), Neuropathologie (FB), Neurochirurgie (BM, SC), Paris, France
| | - Richard Miles
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris 6 UMR S1127, Institut du Cerveau et de la Moelle épinière, Paris, France
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12
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Wellmann M, Álvarez-Ferradas C, Maturana CJ, Sáez JC, Bonansco C. Astroglial Ca 2+-Dependent Hyperexcitability Requires P2Y 1 Purinergic Receptors and Pannexin-1 Channel Activation in a Chronic Model of Epilepsy. Front Cell Neurosci 2018; 12:446. [PMID: 30542266 PMCID: PMC6277884 DOI: 10.3389/fncel.2018.00446] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 11/06/2018] [Indexed: 12/31/2022] Open
Abstract
Astrocytes from the hippocampus of chronic epileptic rats exhibit an abnormal pattern of intracellular calcium oscillations, characterized by an augmented frequency of long lasting spontaneous Ca2+ transients, which are sensitive to purinergic receptor antagonists but resistant to tetrodotoxin. The above suggests that alterations in astroglial Ca2+-dependent excitability observed in the epileptic tissue could arise from changes in astrocyte-to-astrocyte signaling, which is mainly mediated by purines in physiological and pathological conditions. In spite of that, how purinergic signaling contributes to astrocyte dysfunction in epilepsy remains unclear. Here, we assessed the possible contribution of P2Y1R as well as pannexin1 and connexin43 hemichannels—both candidates for non-vesicular ATP-release—by performing astroglial Ca2+ imaging and dye uptake experiments in hippocampal slices from control and fully kindled rats. P2Y1R blockade with MRS2179 decreased the mean duration of astroglial Ca2+ oscillations by reducing the frequency of slow Ca2+ transients, and thereby restoring the balance between slow (ST) and fast transients (FT) in the kindled group. The potential contribution of astroglial pannexin1 and connexin43 hemichannels as pathways for purine release (e.g., ATP) was assessed through dye uptake experiments. Astrocytes from kindled hippocampi exhibit three-fold more EtBr uptake than controls, whereby pannexin1 hemichannels (Panx1 HCs) accounts for almost all dye uptake with only a slight contribution from connexin43 hemichannels (Cx43 HCs). Confirming its functional involvement, Panx1 HCs inhibition decreased the mean duration of astroglial Ca2+ transients and the frequency of slow oscillations in kindled slices, but had no noticeable effects on the control group. As expected, Cx43 HCs blockade did not have any effects over the mean duration of astroglial Ca2+ oscillations. These findings suggest that P2Y1R and Panx1 HCs play a pivotal role in astroglial pathophysiology, which would explain the upregulation of glutamatergic neurotransmission in the epileptic brain and thus represents a new potential pharmacological target for the treatment of drug-refractory epilepsy.
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Affiliation(s)
- Mario Wellmann
- Centro de Neurobiología y Plasticidad Cerebral CNPC, Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile.,Escuela de Fonoaudiología, Facultad de Medicina, Universidad de Valparaíso, Valparaíso, Chile
| | - Carla Álvarez-Ferradas
- Centro de Neurobiología y Plasticidad Cerebral CNPC, Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile.,Escuela de Ciencias de la Salud, Universidad Viña del Mar, Valparaíso, Chile
| | - Carola J Maturana
- Departamento de Ciencias Fisiológicas, Facultad Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.,Instituto de Neurociencias, Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Juan C Sáez
- Departamento de Ciencias Fisiológicas, Facultad Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.,Instituto de Neurociencias, Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Christian Bonansco
- Centro de Neurobiología y Plasticidad Cerebral CNPC, Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
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13
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Vargas-Sánchez K, Mogilevskaya M, Rodríguez-Pérez J, Rubiano MG, Javela JJ, González-Reyes RE. Astroglial role in the pathophysiology of status epilepticus: an overview. Oncotarget 2018; 9:26954-26976. [PMID: 29928494 PMCID: PMC6003549 DOI: 10.18632/oncotarget.25485] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Accepted: 05/09/2018] [Indexed: 12/11/2022] Open
Abstract
Status epilepticus is a medical emergency with elevated morbidity and mortality rates, and represents a leading cause of epilepsy-related deaths. Though status epilepticus can occur at any age, it manifests more likely in children and elderly people. Despite the common prevalence of epileptic disorders, a complete explanation for the mechanisms leading to development of self-limited or long lasting seizures (as in status epilepticus) are still lacking. Apart from neurons, research evidence suggests the involvement of immune and glial cells in epileptogenesis. Among glial cells, astrocytes represent an ideal target for the study of the pathophysiology of status epilepticus, due to their key role in homeostatic balance of the central nervous system. During status epilepticus, astroglial cells are activated by the presence of cytokines, damage associated molecular patterns and reactive oxygen species. The persistent activation of astrocytes leads to a decrease in glutamate clearance with a corresponding accumulation in the synaptic extracellular space, increasing the chance of neuronal excitotoxicity. Moreover, major alterations in astrocytic gap junction coupling, inflammation and receptor expression, facilitate the generation of seizures. Astrocytes are also involved in dysregulation of inhibitory transmission in the central nervous system and directly participate in ionic homeostatic alterations during status epilepticus. In the present review, we focus on the functional and structural changes in astrocytic activity that participate in the development and maintenance of status epilepticus, with special attention on concurrent inflammatory alterations. We also include potential astrocytic treatment targets for status epilepticus.
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Affiliation(s)
- Karina Vargas-Sánchez
- Biomedical Sciences Research Group, School of Medicine, Universidad Antonio Nariño, Bogotá, Colombia
| | | | - John Rodríguez-Pérez
- Biomedical Sciences Research Group, School of Medicine, Universidad Antonio Nariño, Bogotá, Colombia
| | - María G Rubiano
- Biomedical Sciences Research Group, School of Medicine, Universidad Antonio Nariño, Bogotá, Colombia
| | - José J Javela
- Grupo de Clínica y Salud Mental, Programa de Psicología, Universidad Católica de Pereira, Pereira, Colombia
| | - Rodrigo E González-Reyes
- Universidad del Rosario, Escuela de Medicina y Ciencias de la Salud, GI en Neurociencias-NeURos, Bogotá, Colombia
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14
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Adams SD, Kouzani AZ, Tye SJ, Bennet KE, Berk M. An investigation into closed-loop treatment of neurological disorders based on sensing mitochondrial dysfunction. J Neuroeng Rehabil 2018; 15:8. [PMID: 29439744 PMCID: PMC5811973 DOI: 10.1186/s12984-018-0349-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 02/05/2018] [Indexed: 12/14/2022] Open
Abstract
Dynamic feedback based closed-loop medical devices offer a number of advantages for treatment of heterogeneous neurological conditions. Closed-loop devices integrate a level of neurobiological feedback, which allows for real-time adjustments to be made with the overarching aim of improving treatment efficacy and minimizing risks for adverse events. One target which has not been extensively explored as a potential feedback component in closed-loop therapies is mitochondrial function. Several neurodegenerative and psychiatric disorders including Parkinson's disease, Major Depressive disorder and Bipolar disorder have been linked to perturbations in the mitochondrial respiratory chain. This paper investigates the potential to monitor this mitochondrial function as a method of feedback for closed-loop neuromodulation treatments. A generic model of the closed-loop treatment is developed to describe the high-level functions of any system designed to control neural function based on mitochondrial response to stimulation, simplifying comparison and future meta-analysis. This model has four key functional components including: a sensor, signal manipulator, controller and effector. Each of these components are described and several potential technologies for each are investigated. While some of these candidate technologies are quite mature, there are still technological gaps remaining. The field of closed-loop medical devices is rapidly evolving, and whilst there is a lot of interest in this area, widespread adoption has not yet been achieved due to several remaining technological hurdles. However, the significant therapeutic benefits offered by this technology mean that this will be an active area for research for years to come.
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Affiliation(s)
- Scott D. Adams
- School of Engineering, Deakin University, Geelong, VIC 3216 Australia
| | - Abbas Z. Kouzani
- School of Engineering, Deakin University, Geelong, VIC 3216 Australia
| | - Susannah J. Tye
- Department of Psychiatry and Psychology, Mayo Clinic, Rochester, MN 55905 USA
| | - Kevin E. Bennet
- Division of Engineering, Mayo Clinic, Rochester, MN 55905 USA
| | - Michael Berk
- School of Medicine, Deakin University, Waurn Ponds, VIC 3216 Australia
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15
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Kardos J, Héja L, Jemnitz K, Kovács R, Palkovits M. The nature of early astroglial protection-Fast activation and signaling. Prog Neurobiol 2017; 153:86-99. [PMID: 28342942 DOI: 10.1016/j.pneurobio.2017.03.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 09/22/2016] [Accepted: 03/05/2017] [Indexed: 12/14/2022]
Abstract
Our present review is focusing on the uniqueness of balanced astroglial signaling. The balance of excitatory and inhibitory signaling within the CNS is mainly determined by sharp synaptic transients of excitatory glutamate (Glu) and inhibitory γ-aminobutyrate (GABA) acting on the sub-second timescale. Astroglia is involved in excitatory chemical transmission by taking up i) Glu through neurotransmitter-sodium transporters, ii) K+ released due to presynaptic action potential generation, and iii) water keeping osmotic pressure. Glu uptake-coupled Na+ influx may either ignite long-range astroglial Ca2+ transients or locally counteract over-excitation via astroglial GABA release and increased tonic inhibition. Imbalance of excitatory and inhibitory drives is associated with a number of disease conditions, including prevalent traumatic and ischaemic injuries or the emergence of epilepsy. Therefore, when addressing the potential of early therapeutic intervention, astroglial signaling functions combating progress of Glu excitotoxicity is of critical importance. We suggest, that excitotoxicity is linked primarily to over-excitation induced by the impairment of astroglial Glu uptake and/or GABA release. Within this framework, we discuss the acute alterations of Glu-cycling and metabolism and conjecture the therapeutic promise of regulation. We also confer the role played by key carrier proteins and enzymes as well as their interplay at the molecular, cellular, and organ levels. Moreover, based on our former studies, we offer potential prospect on the emerging theme of astroglial succinate sensing in course of Glu excitotoxicity.
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Affiliation(s)
- Julianna Kardos
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Hungary.
| | - László Héja
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Hungary
| | - Katalin Jemnitz
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Hungary
| | - Richárd Kovács
- Institute of Neurophysiology, Charité - Universitätsmedizin, Berlin, Germany
| | - Miklós Palkovits
- Human Brain Tissue Bank and Laboratory, Semmelweis University, Budapest, Hungary
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16
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Role of the purinergic signaling in epilepsy. Pharmacol Rep 2016; 69:130-138. [PMID: 27915186 DOI: 10.1016/j.pharep.2016.09.018] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 09/20/2016] [Accepted: 09/21/2016] [Indexed: 01/19/2023]
Abstract
Adenine nucleotides and adenosine are signaling molecules that activate purinergic receptors P1 and P2. Activation of A1 adenosine receptors has an anticonvulsant action, whereas activation of A2A receptors might initiate seizures. Therefore, a significant limitation to the use of A1 receptor agonists as drugs in the CNS might be their peripheral side effects. The anti-epileptic activity of adenosine is related to its increased concentration outside the cell. This increase might result from the inhibition of the equilibrative nucleoside transporters (ENTs). Moreover, the implantation of implants or stem cells into the brain might cause slow and persistent increases in adenosine concentrations in the extracellular spaces of the brain. The role of adenosine in seizure inhibition has been confirmed by results demonstrating that in patients with epilepsy, the adenosine kinase (ADK) present in astrocytes is the only purine-metabolizing enzyme that exhibits increased expression. Increased ADK activity causes intensified phosphorylation of adenosine to 5'-AMP, which therefore lowers the adenosine level in the extracellular spaces. These changes might initiate astrogliosis and epileptogenesis, which are the manifestations of epilepsy. Seizures might induce inflammatory processes and vice versa. Activation of P2X7 receptors causes intensified release of pro-inflammatory cytokines (IL-1β and TNF-α) and activates metabolic pathways that induce inflammatory processes in the CNS. Therefore, antagonists of P2X7 and the interleukin 1β receptor might be efficient drugs for recurring seizures and prolonged status epilepticus. Inhibitors of ADK would simultaneously inhibit the seizures, prevent the astrogliosis and epileptogenesis processes and prevent the formation of new epileptogenic foci. Therefore, these drugs might become beneficial seizure-suppressing drugs.
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17
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Crucial role of astrocytes in temporal lobe epilepsy. Neuroscience 2016; 323:157-69. [DOI: 10.1016/j.neuroscience.2014.12.047] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 12/25/2014] [Accepted: 12/30/2014] [Indexed: 11/30/2022]
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18
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Glutamate metabolism of astrocytes during hyperbaric oxygen exposure and its effects on central nervous system oxygen toxicity. Neuroreport 2016; 27:73-9. [DOI: 10.1097/wnr.0000000000000493] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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19
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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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20
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Effect of GLT-1 modulator and P2X7 antagonists alone and in combination in the kindling model of epilepsy in rats. Epilepsy Behav 2015; 48:4-14. [PMID: 26037843 DOI: 10.1016/j.yebeh.2015.04.056] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/25/2014] [Revised: 04/21/2015] [Accepted: 04/22/2015] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Multiple lines of investigation have explored the role of glutamatergic and purinergic systems in epilepsy, related cognitive impairment, and oxidative stress. Glutamate transporters, particularly GLT-1 expression, were found to be decreased, and purinergic receptor, P2X7 expression, was found to be increased in brain tissue associated with epilepsy. The present study was carried out to investigate the effect of ceftriaxone (GLT-1 upregulator) and Brilliant Blue G (P2X7 antagonist) against PTZ-induced kindling in rats. The study was further extended to elucidate the cross-link between glutamatergic and purinergic pathways in epilepsy. MATERIAL AND METHODS Systemic administration of subconvulsant dose of PTZ (30 mg/kg) every other day for 27days (14 injections) significantly increased the mean kindling, and developed generalized tonic-clonic seizures, and reduced motor co-ordination, cognitive skills, oxidative defense (increases lipid peroxidation, nitrite levels and decreases GSH level) and acetylcholinesterase enzyme activities in the cortex and subcortical region. Treatments with CEF (100 and 200mg/kg) and BBG (15 and 30 mg/kg) alone and in combination (CEF 100mg/kg and BBG 15 mg/kg) significantly decreased the mean kindling score and restored behavioral and oxidative defense activities compared with treatment with PTZ. CONCLUSIONS The combination of both the drugs was shown to have better effect in preventing kindled seizures and a significantly synergistic effect compared with their effect alone in PTZ-kindled rats. The present study elucidated the mechanistic role of GLT-1 modulator and selective P2X7 antagonist and their combination against PTZ-induced kindling. The study for the first time demonstrated the cross-link between glutamatergic and purinergic pathways in epilepsy treatment.
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Wu XL, Tang YC, Lu QY, Xiao XL, Song TB, Tang FR. Astrocytic Cx 43 and Cx 40 in the mouse hippocampus during and after pilocarpine-induced status epilepticus. Exp Brain Res 2015; 233:1529-39. [PMID: 25690864 DOI: 10.1007/s00221-015-4226-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Accepted: 02/09/2015] [Indexed: 12/15/2022]
Abstract
Astrocytes have now been well accepted to play important roles in epileptogenesis by controlling gliotransmitter release and neuronal excitability, contributing to blood-brain barrier dysfunction and involving in brain inflammation. Recent studies indicate that abnormal expression of gap junction protein connexin (Cx) may also be a contributing factor for seizure generation. To further address this issue, we investigated the progressive changes of Cx 43 and Cx 40 in the mouse hippocampus at 4 h, 1 day, 1 week and 2 months during and after pilocarpine-induced status epilepticus (PISE). The co-localization of Cx 43 and Cx 40 with glial fibrillary acidic protein (GFAP) was also examined. We observed that Cx 43 and Cx 40 protein expression remained unaltered at 4 h during and at 1 day (acute stage) after PISE. However, their expression was significantly increased in CA1 and CA3 areas and in the dentate gyrus at 1 week (latent stage) and 2 months (chronic stage) after PISE. Double immunofluorescence labeling indicated the localization of Cx 43 and Cx 40 in astrocytes. Combined with progressive neuronal loss in the mouse hippocampus, our results suggest that the increase in gap junctions in the neuronoglial syncytium of reactive astrocytes may be implicated in synchronization of hippocampal hyperactivity leading to neuronal loss and epileptogenesis.
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Affiliation(s)
- X L Wu
- Department of Human Anatomy, Histology and Embryology, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, People's Republic of China
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22
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Ortiz R, Ulrich H, Zarate CA, Machado-Vieira R. Purinergic system dysfunction in mood disorders: a key target for developing improved therapeutics. Prog Neuropsychopharmacol Biol Psychiatry 2015; 57:117-31. [PMID: 25445063 PMCID: PMC4262688 DOI: 10.1016/j.pnpbp.2014.10.016] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 10/20/2014] [Accepted: 10/28/2014] [Indexed: 02/09/2023]
Abstract
Uric acid and purines (such as adenosine) regulate mood, sleep, activity, appetite, cognition, memory, convulsive threshold, social interaction, drive, and impulsivity. A link between purinergic dysfunction and mood disorders was first proposed a century ago. Interestingly, a recent nationwide population-based study showed elevated risk of gout in subjects with bipolar disorder (BD), and a recent meta-analysis and systematic review of placebo-controlled trials of adjuvant purinergic modulators confirmed their benefits in bipolar mania. Uric acid may modulate energy and activity levels, with higher levels associated with higher energy and BD spectrum. Several recent genetic studies suggest that the purinergic system - particularly the modulation of P1 and P2 receptor subtypes - plays a role in mood disorders, lending credence to this model. Nucleotide concentrations can be measured using brain spectroscopy, and ligands for in vivo positron emission tomography (PET) imaging of adenosine (P1) receptors have been developed, thus allowing potential target engagement studies. This review discusses the key role of the purinergic system in the pathophysiology of mood disorders. Focusing on this promising therapeutic target may lead to the development of therapies with antidepressant, mood stabilization, and cognitive effects.
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Affiliation(s)
- Robin Ortiz
- Experimental Therapeutics and Pathophysiology Branch, National Institute of Mental Health, Division of Intramural Research Programs, National Institutes of Health, Bethesda, MD, USA.
| | - Henning Ulrich
- Departament of Biochemistry, University of Sao Paulo, Sao Paulo, Brazil.
| | - Carlos A Zarate
- Experimental Therapeutics and Pathophysiology Branch, National Institute of Mental Health, Division of Intramural Research Programs, National Institutes of Health, Bethesda, MD, USA.
| | - Rodrigo Machado-Vieira
- Experimental Therapeutics and Pathophysiology Branch, National Institute of Mental Health, Division of Intramural Research Programs, National Institutes of Health, Bethesda, MD, USA; Laboratory of Neuroscience, LIM27, University of Sao Paulo, Sao Paulo, Brazil.
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Pathological potential of astroglial purinergic receptors. ADVANCES IN NEUROBIOLOGY 2014; 11:213-56. [PMID: 25236731 DOI: 10.1007/978-3-319-08894-5_11] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Acute brain injury and neurodegenerative disorders may result in astroglial activation. Astrocytes are able to determine the progression and outcome of these neuropathologies in a beneficial or detrimental way. Nucleotides, e.g. adenosine 5'-triphosphate (ATP), released after acute or chronic neuronal injury, are important mediators of glial activation and astrogliosis.Acute injury may cause significant changes in ATP balance, resulting in (1) a decline of intracellular ATP levels and (2) an increase in extracellular ATP concentrations via efflux from the intracellular space. The released ATP may have trophic effects, but can also act as a proinflammatory mediator or cytotoxic factor, inducing necrosis/apoptosis as a universal "danger" signal. Furthermore, ATP, primarily released from astrocytes, is a means of communication between neurons, glial cells, and intracerebral blood vessels.Astrocytes express a heterogeneous battery of purinergic ionotropic and metabotropic receptors (P2XRs and P2YRs, respectively) to respond to extracellular nucleotides.In this chapter, we summarize the contemporary knowledge on the pathological potential of P2Rs in relation to changes of astrocytic functions, determined by distinct molecular signaling cascades, in a variety of diseases. We discuss specific aspects of reactive astrogliosis, with respect to the involvement of prominent receptor subtypes, such as the P2X7 and P2Y1/2Rs. Examples of purinergic signaling of microglia, oligodendrocytes, and blood vessels under pathophysiological conditions will also be presented.The understanding of the pathological potential of purinergic signaling in "controlling and fine-tuning" of astrocytic responses is important for identifying possible therapeutic principles to treat acute and chronic central nervous system diseases.
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Jacob PF, Vaz SH, Ribeiro JA, Sebastião AM. P2Y1 receptor inhibits GABA transport through a calcium signalling-dependent mechanism in rat cortical astrocytes. Glia 2014; 62:1211-26. [PMID: 24733747 DOI: 10.1002/glia.22673] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 03/29/2014] [Accepted: 03/31/2014] [Indexed: 12/16/2022]
Abstract
Astrocytes express a variety of purinergic (P2) receptors, involved in astrocytic communication through fast increases in [Ca(2+) ]i . Of these, the metabotropic ATP receptors (P2Y) regulate cytoplasmic Ca(2+) levels through the PLC-PKC pathway. GABA transporters are a substrate for a number of Ca(2+) -related kinases, raising the possibility that calcium signalling in astrocytes impact the control of extracellular levels of the major inhibitory transmitter in the brain. To access this possibility we tested the influence of P2Y receptors upon GABA transport into astrocytes. Mature primary cortical astroglial-enriched cultures expressed functional P2Y receptors, as evaluated through Ca(2+) imaging, being P2Y1 the predominant P2Y receptor subtype. ATP (100 μM, for 1 min) caused an inhibition of GABA transport through either GAT-1 or GAT-3 transporters, decreasing the Vmax kinetic constant. ATP-induced inhibition of GATs activity was still evident in the presence of adenosine deaminase, precluding an adenosine-mediated effect. This, was mimicked by a specific agonist for the P2Y1,12,13 receptor (2-MeSADP). The effect of 2-MeSADP on GABA transport was blocked by the P2 (PPADS) and P2Y1 selective (MRS2179) receptor antagonists, as well as by the PLC inhibitor (U73122). 2-MeSADP failed to inhibit GABA transport in astrocytes where intracellular calcium had been chelated (BAPTA-AM) or where calcium stores were depleted (α-cyclopiazonic acid, CPA). In conclusion, P2Y1 receptors in astrocytes inhibit GABA transport through a mechanism dependent of P2Y1 -mediated calcium signalling, suggesting that astrocytic calcium signalling, which occurs as a consequence of neuronal firing, may operate a negative feedback loop to enhance extracellular levels of GABA.
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Affiliation(s)
- Pedro F Jacob
- Institute of Pharmacology and Neurosciences, Faculty of Medicine, University of Lisbon, Lisbon, Portugal; Neurosciences Unit, Institute of Molecular Medicine University of Lisbon, Lisbon, Portugal
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Losi G, Cammarota M, Carmignoto G. The role of astroglia in the epileptic brain. Front Pharmacol 2012; 3:132. [PMID: 22807916 PMCID: PMC3395023 DOI: 10.3389/fphar.2012.00132] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Accepted: 06/23/2012] [Indexed: 11/13/2022] Open
Abstract
Epilepsies comprise a family of multifactorial neurological disorders that affect at least 50 million people worldwide. Despite a long history of neurobiological and clinical studies the mechanisms that lead the brain network to a hyperexcitable state and to the intense, massive neuronal discharges reflecting a seizure episode are only partially defined. Most epilepsies of genetic origin are related to mutations in ionic channels that cause neuronal hyperexcitability. However, idiopathic epilepsies of unclear origin represent the majority of these brain disorders. A large body of evidence suggests that in the epileptic brain neurons are not the only players. Indeed, the glial cell astrocyte is known to be morphologically and functionally altered in different types of epilepsy. Although it is unclear whether these astrocyte dysfunctions can have a causative role in epileptogenesis, the hypothesis that astrocytes contribute to epileptiform activities recently received a considerable experimental support. Notably, currently used antiepileptic drugs, that act mainly on neuronal ion channels, are ineffective in a large group of patients. Clarifying astrocyte functions in the epileptic brain tissue could unveil astrocytes as novel therapeutic targets. In this review we present first a short overview on the role of astrocytes in the epileptic brain starting from the "historical" observations on their fundamental modulation of brain homeostasis, such as the control of water content, ionic equilibrium, and neurotransmitters concentrations. We then focus our review on most recent studies that hint at a distinct contribution of these cells in the generation of focal epileptiform activities.
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Affiliation(s)
- Gabriele Losi
- Institute of Neuroscience of the National Research Council and Department of Biomedical Sciences, University of Padova Padova, Italy
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Franke H, Verkhratsky A, Burnstock G, Illes P. Pathophysiology of astroglial purinergic signalling. Purinergic Signal 2012; 8:629-57. [PMID: 22544529 DOI: 10.1007/s11302-012-9300-0] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 02/01/2012] [Indexed: 12/13/2022] Open
Abstract
Astrocytes are fundamental for central nervous system (CNS) physiology and are the fulcrum of neurological diseases. Astroglial cells control development of the nervous system, regulate synaptogenesis, maturation, maintenance and plasticity of synapses and are central for nervous system homeostasis. Astroglial reactions determine progression and outcome of many neuropathologies and are critical for regeneration and remodelling of neural circuits following trauma, stroke, ischaemia or neurodegenerative disorders. They secrete multiple neurotransmitters and neurohormones to communicate with neurones, microglia and the vascular walls of capillaries. Signalling through release of ATP is the most widespread mean of communication between astrocytes and other types of neural cells. ATP serves as a fast excitatory neurotransmitter and has pronounced long-term (trophic) roles in cell proliferation, growth, and development. During pathology, ATP is released from damaged cells and acts both as a cytotoxic factor and a proinflammatory mediator, being a universal "danger" signal. In this review, we summarise contemporary knowledge on the role of purinergic receptors (P2Rs) in a variety of diseases in relation to changes of astrocytic functions and nucleotide signalling. We have focussed on the role of the ionotropic P2X and metabotropic P2YRs working alone or in concert to modify the release of neurotransmitters, to activate signalling cascades and to change the expression levels of ion channels and protein kinases. All these effects are of great importance for the initiation, progression and maintenance of astrogliosis-the conserved and ubiquitous glial defensive reaction to CNS pathologies. We highlighted specific aspects of reactive astrogliosis, especially with respect to the involvement of the P2X(7) and P2Y(1)R subtypes. Reactive astrogliosis exerts both beneficial and detrimental effects in a context-specific manner determined by distinct molecular signalling cascades. Understanding the role of purinergic signalling in astrocytes is critical to identifying new therapeutic principles to treat acute and chronic neurological diseases.
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Affiliation(s)
- Heike Franke
- Rudolf Boehm Institute of Pharmacology and Toxicology, University of Leipzig, Härtelstrasse 16-18, 04107, Leipzig, Germany.
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Kumaria A, Tolias CM. Is there a role for vagus nerve stimulation therapy as a treatment of traumatic brain injury? Br J Neurosurg 2012; 26:316-20. [PMID: 22404761 DOI: 10.3109/02688697.2012.663517] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
This paper aims to review the current literature on vagus nerve stimulation (VNS) use in animal models of traumatic brain injury (TBI) and explore its potential role in treatment of human TBI. A MEDLINE search yielded four primary papers from the same group that demonstrated VNS mediated improvement following fluid percussion models of TBI in rats, seen as motor and cognitive improvements, reduction of cortical oedema and neuroprotective effects. The underlying mechanisms are elusive and authors attribute these to attenuation of post traumatic seizures, a noradrenergic mechanism and as yet undetermined mechanisms. Reviewing and elaborating on these ideas, we speculate other potential mechanisms including attenuation of peri-infarct depolarisations, attenuation of glutamate mediated excitotoxicity, stabilisation of intracranial pressure, enhancement of synaptic plasticity, upregulation of endogenous neurogenesis and anti-inflammatory effects may have a role. Although this data unequivocally shows that VNS improves outcome from TBI in animal models, it remains to be determined if these findings translate clinically. Further studies are warranted.
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Affiliation(s)
- Ashwin Kumaria
- Department of Neurosurgery, Wessex Neurological Centre, Southampton, UK.
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Astrocyte dysfunction in temporal lobe epilepsy: K+ channels and gap junction coupling. Glia 2012; 60:1192-202. [DOI: 10.1002/glia.22313] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 01/27/2012] [Accepted: 01/27/2012] [Indexed: 12/11/2022]
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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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Siebel AM, Piato AL, Capiotti KM, Seibt KJ, Bogo MR, Bonan CD. PTZ-induced seizures inhibit adenosine deamination in adult zebrafish brain membranes. Brain Res Bull 2011; 86:385-9. [PMID: 21907764 DOI: 10.1016/j.brainresbull.2011.08.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Revised: 08/10/2011] [Accepted: 08/29/2011] [Indexed: 12/20/2022]
Abstract
Adenosine exerts neuromodulatory functions with mostly inhibitory effects, being considered an endogenous anticonvulsant. The hydrolysis of ATP by ectonucleotidases is an important source of adenosine, and adenosine deaminase (ADA) contributes to the regulation of this nucleoside concentration through its deamination. In this study, we tested the effect of pentylenetetrazole (PTZ)-induced seizures on ectonucleotidase and ADA activities in adult zebrafish brain. Our results have demonstrated that PTZ treatments did not alter ectonucleotidase and ADA activities in membranes and soluble fraction, respectively. However, ecto-ADA activity was significantly decreased in brain membranes of animals exposed to 5mM and 15 mM PTZ treatments (22.4% and 29.5%, respectively) when compared to the control group. Semiquantitative RT-PCR analysis did not show significant changes after the PTZ exposure on ADA gene expression. The decreased adenosine deamination observed in this study suggests a modulation of extracellular adenosine levels during PTZ-induced seizures in zebrafish.
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Affiliation(s)
- Anna Maria Siebel
- Laboratório de Neuroquímica e Psicofarmacologia, Departamento de Biologia Celular e Molecular, Programa de Pós-Graduação em Biologia Celular e Molecular, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Avenida Ipiranga, 6681, 90619-900 Porto Alegre, RS, Brazil
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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: 315] [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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Igelström KM, Shirley CH, Heyward PM. Low-magnesium medium induces epileptiform activity in mouse olfactory bulb slices. J Neurophysiol 2011; 106:2593-605. [PMID: 21832029 DOI: 10.1152/jn.00601.2011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Magnesium-free medium can be used in brain slice studies to enhance glutamate receptor function, but this manipulation causes seizure-like activity in many cortical areas. The rodent olfactory bulb (OB) slice is a popular preparation, and potentially ictogenic ionic conditions have often been used to study odor processing. We studied low Mg(2+)-induced epileptiform discharges in mouse OB slices using extracellular and whole cell electrophysiological recordings. Low-Mg(2+) medium induced two distinct types of epileptiform activity: an intraglomerular delta-frequency oscillation resembling slow sniff-induced activity and minute-long seizure-like events (SLEs) consisting of large negative-going field potentials accompanied by sustained depolarization of output neurons. SLEs were dependent on N-methyl-D-aspartate receptors and sodium currents and were facilitated by α-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptors. The events were initiated in the glomerular layer and propagated laterally through the external plexiform layer at a slow time scale. Our findings confirm that low-Mg(2+) medium should be used with caution in OB slices. Furthermore, the SLEs resembled the so-called slow direct current (DC) shift of clinical and experimental seizures, which has recently been recognized as being of great clinical importance. The OB slice may therefore provide a robust and unique in vitro model of acute seizures in which mechanisms of epileptiform DC shifts can be studied in isolation from fast oscillations.
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Affiliation(s)
- Kajsa M Igelström
- Dept. of Physiology, Univ. of Otago, PO Box 913, Dunedin 9054, New Zealand.
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Rieder B, Neuhaus HE. Identification of an Arabidopsis plasma membrane-located ATP transporter important for anther development. THE PLANT CELL 2011; 23:1932-44. [PMID: 21540435 PMCID: PMC3123944 DOI: 10.1105/tpc.111.084574] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
ATP acts as an extracellular signal molecule in plants. However, the nature of the mechanisms that export this compound into the apoplast are under debate. We identified the protein PM-ANT1 as a candidate transporter able to mediate ATP export. PM-ANT1 joins the mitochondrial carrier family, lacks an N-terminal amino acid extension required for organelle localization, and locates to the plasma membrane. Recombinant PM-ANT1 transports ATP, and the gene is substantially expressed in mature pollen grains. Artificial microRNA (amiRNA) mutants show reduced silique length and less seeds per silique but increased seed weight associated with unchanged pollen viability. Anthers from amiRNA mutants exhibited a normal early development, but stomium breakage is inhibited, leading to impaired anther dehiscence. This results in reduced self-pollination and thus decreased fertilization efficiency. amiRNA pollen grains showed increased intracellular ATP levels but decreased extracellular ATP levels. The latter effects are in line with transport properties of recombinant PM-ANT1, supporting in planta that functional PM-ANT1 resides in the plasma membrane and concur with the PM-ANT1 expression pattern. We assume that PM-ANT1 contributes to ATP export during pollen maturation. ATP export may serve as an extracellular signal required for anther dehiscence and is a novel factor critical for pollination and autogamy.
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Benedetti B, Matyash V, Kettenmann H. Astrocytes control GABAergic inhibition of neurons in the mouse barrel cortex. J Physiol 2011; 589:1159-72. [PMID: 21224221 DOI: 10.1113/jphysiol.2010.203224] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Astrocytes in the barrel cortex respond with a transient Ca2+ increase to neuronal stimulation and this response is restricted to the stimulated barrel field. In the present study we suppressed the astrocyte response by dialysing these cells with the Ca2+ chelator BAPTA. Electrical stimulation triggered a depolarization in stellate or pyramidal ‘regular spiking' neurons from cortex layer 4 and 2/3 and this response was augmented in amplitude and duration after astrocytes were dialysed with BAPTA. Combined blockade of GABAA and GABAB receptors mimicked the effect of BAPTA dialysis, while glutamate receptor blockers had no effect. Moreover, the frequency of spontaneous postsynaptic currents was increased after BAPTA dialysis. Outside the range of BAPTA dialysis astrocytes responded with a Ca2+ increase, but in contrast to control, the response was no longer restricted to one barrel field. Our findings indicate that astrocytes control neuronal inhibition in the barrel cortex.
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Affiliation(s)
- B Benedetti
- Max-Delbrück-Centre for Molecular Medicine, Cellular Neuroscience, Robert-Rössle-Str. 10, 13092 Berlin-Buch, Berlin, Germany.
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Dale N, Frenguelli BG. Release of adenosine and ATP during ischemia and epilepsy. Curr Neuropharmacol 2010; 7:160-79. [PMID: 20190959 PMCID: PMC2769001 DOI: 10.2174/157015909789152146] [Citation(s) in RCA: 173] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Revised: 04/15/2009] [Accepted: 05/01/2009] [Indexed: 12/17/2022] Open
Abstract
Eighty years ago Drury & Szent-Györgyi described the actions of adenosine, AMP (adenylic acid) and ATP (pyrophosphoric or diphosphoric ester of adenylic acid) on the mammalian cardiovascular system, skeletal muscle, intestinal and urinary systems. Since then considerable insight has been gleaned on the means by which these compounds act, not least of which in the distinction between the two broad classes of their respective receptors, with their many subtypes, and the ensuing diversity in cellular consequences their activation invokes. These myriad actions are of course predicated on the release of the purines into the extracellular milieu, but, surprisingly, there is still considerable ambiguity as to how this occurs in various physiological and pathophysiological conditions. In this review we summarise the release of ATP and adenosine during seizures and cerebral ischemia and discuss mechanisms by which the purines adenosine and ATP may be released from cells in the CNS under these conditions.
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Affiliation(s)
- Nicholas Dale
- Department of Biological Sciences, University of Warwick, Coventry, CV4 7AL, UK
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Uncoupling of astrogliosis from epileptogenesis in adenosine kinase (ADK) transgenic mice. ACTA ACUST UNITED AC 2009; 4:91-9. [PMID: 19674507 DOI: 10.1017/s1740925x09990135] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The astrocytic enzyme adenosine kinase (ADK) is a key negative regulator of the brain's endogenous anticonvulsant adenosine. Astrogliosis with concomitant upregulation of ADK is part of the epileptogenic cascade and contributes to seizure generation. To molecularly dissect the respective roles of astrogliosis and ADK-expression for seizure generation, we used a transgenic approach to uncouple ADK-expression from astrogliosis: in Adk-tg mice the endogenous Adk-gene was deleted and replaced by a ubiquitously expressed Adk-transgene with novel ectopic expression in pyramidal neurons, resulting in spontaneous seizures. Here, we followed a unique approach to selectively injure the CA3 of these Adk-tg mice. Using this strategy, we had the opportunity to study astrogliosis and epileptogenesis in the absence of the endogenous astrocytic Adk-gene. After triggering epileptogenesis we demonstrate astrogliosis without upregulation of ADK, but lack of seizures, whereas matching wild-type animals developed astrogliosis with upregulation of ADK and spontaneous recurrent seizures. By uncoupling ADK-expression from astrogliosis, we demonstrate that global expression levels of ADK rather than astrogliosis per se contribute to seizure generation.
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Grosso S, Rocchi R, Margollicci M, Vatti G, Luddi A, Marchi F, Balestri P. Postictal serum nucleotidases activities in patients with epilepsy. Epilepsy Res 2009; 84:15-20. [PMID: 19157784 DOI: 10.1016/j.eplepsyres.2008.11.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2008] [Revised: 11/21/2008] [Accepted: 11/30/2008] [Indexed: 12/20/2022]
Abstract
Adenosine, a potent anticonvulsant, can be produced in the body by the hydrolysis of adenine nucleotides through the action of ecto- or soluble nucleotidases. Changes in nucleotide hydrolysis occur after pentylenetetrazol-induced epileptic events. We evaluated serum ATP, ADP and AMP hydrolysis rates and soluble nucleotide phosphodiesterase (PDEase) activity at 5, 10, 15, 30 and 60 min, and 12h following an epileptic event. Fifteen patients (seven female, eight male; mean age 15.5 years) were included in the study. The type of seizure was generalized in four patients and was localization related in the remaining 11. There were no differences in adenine nucleotide hydrolysis rates between patients and healthy subjects in the interictal stage. In comparison with controls, ATP, ADP and AMP hydrolysis rates were significantly increased at 5 min (53+/-1.4%, 79.2+/-2.8% and 37.0+/-2.6%, respectively) and up to 30 min following the epileptic event. In contrast to ADP and AMP, ATP hydrolysis remained significantly increased at 60 min (71.4+/-1.6%), returning to the basal level after 12h. Serum PDEase activity was also significantly higher in the patients than in healthy subjects, peaking at 15 min (61+/-2.9%) and remaining significantly increased up to 60 min (4.6+/-1.2%) following the epileptic episode. Globally, the variations in the postictal serum ADP hydrolysis rate almost overlapped those of AMP hydrolysis, whereas changes in the ATP hydrolysis rate overlapped those of PDEase activity. The clinical significance of this elevation in postictal soluble serum nucleotidase activity remains to be clarified. However, it is possible to hypothesize that the higher nucleotidase activity might play a role in the modulation of epileptic events.
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Affiliation(s)
- Salvatore Grosso
- Department of Pediatrics, Pediatric Neurology Section, University of Siena, Siena, Italy.
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Doná F, Ulrich H, Persike DS, Conceição IM, Blini JP, Cavalheiro EA, Fernandes MJS. Alteration of purinergic P2X4 and P2X7 receptor expression in rats with temporal-lobe epilepsy induced by pilocarpine. Epilepsy Res 2008; 83:157-67. [PMID: 19084381 DOI: 10.1016/j.eplepsyres.2008.10.008] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Revised: 10/20/2008] [Accepted: 10/22/2008] [Indexed: 11/29/2022]
Abstract
SUMMARY Although ATP and P2X receptor activity have been lately associated with epilepsy, little is known regarding their exact roles in epileptogenesis. Temporal-lobe epilepsy (TLE) in rat was induced by pilocarpine in order to study changes of hippocampal P2X(2), P2X(4) and P2X(7) receptor expression during acute, latent or chronic phases of epilepsy. During acute and chronic phases increased P2X(7) receptor expression was principally observed in glial cells and glutamatergic nerve terminals, suggesting participation of this receptor in the activation of inflammatory and excitotoxic processes during epileptogenesis. No significant alterations of hippocampal P2X(2) and P2X(4) receptor expression was noted during the acute or latent phase when compared to the control group, indicating that these receptors are not directly involved with the initiation of epilepsy. However, the reduction of hippocampal P2X(4) receptor immunostaining in the chronic phase could reflect neuronal loss or decreased GABAergic signaling.
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Affiliation(s)
- Flavia Doná
- Departamento Neurologia/Neurocirurgia, Universidade Federal de São Paulo, UNIFESP, São Paulo, Brazil
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