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Wendlandt M, Kürten AJ, Beiersdorfer A, Schubert C, Samad-Yazdtchi K, Sauer J, Pinto MC, Schulz K, Friese MA, Gee CE, Hirnet D, Lohr C. A 2A adenosine receptor-driven cAMP signaling in olfactory bulb astrocytes is unaffected in experimental autoimmune encephalomyelitis. Front Immunol 2023; 14:1273837. [PMID: 38077336 PMCID: PMC10701430 DOI: 10.3389/fimmu.2023.1273837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 11/06/2023] [Indexed: 12/18/2023] Open
Abstract
Introduction The cyclic nucleotide cyclic adenosine monophosphate (cAMP) is a ubiquitous second messenger, which is known to play an important anti-inflammatory role. Astrocytes in the central nervous system (CNS) can modulate inflammation but little is known about the significance of cAMP in their function. Methods We investigated cAMP dynamics in mouse olfactory bulb astrocytes in brain slices prepared from healthy and experimental autoimmune encephalomyelitis (EAE) mice. Results The purinergic receptor ligands adenosine and adenosine triphosphate (ATP) both induced transient increases in cAMP in astrocytes expressing the genetically encoded cAMP sensor Flamindo2. The A2A receptor antagonist ZM241385 inhibited the responses. Similar transient increases in astrocytic cAMP occurred when olfactory receptor neurons were stimulated electrically, resulting in ATP release from the stimulated axons that increased cAMP, again via A2A receptors. Notably, A2A-mediated responses to ATP and adenosine were not different in EAE mice as compared to healthy mice. Discussion Our results indicate that ATP, synaptically released by afferent axons in the olfactory bulb, is degraded to adenosine that acts on A2A receptors in astrocytes, thereby increasing the cytosolic cAMP concentration. However, this pathway is not altered in the olfactory bulb of EAE mice.
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Affiliation(s)
- Marina Wendlandt
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Alina J. Kürten
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | | | - Charlotte Schubert
- Institute of Neuroimmunology and Multiple Sclerosis (INIMS), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | | | - Jessica Sauer
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - M. Carolina Pinto
- Institute of Synaptic Physiology, Center for Molecular Neurobiology Hamburg, Hamburg, Germany
| | - Kristina Schulz
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Manuel A. Friese
- Institute of Neuroimmunology and Multiple Sclerosis (INIMS), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christine E. Gee
- Institute of Synaptic Physiology, Center for Molecular Neurobiology Hamburg, Hamburg, Germany
| | - Daniela Hirnet
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Christian Lohr
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
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2
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Madeira D, Lopes CR, Simões AP, Canas PM, Cunha RA, Agostinho P. Astrocytic A 2A receptors silencing negatively impacts hippocampal synaptic plasticity and memory of adult mice. Glia 2023. [PMID: 37183905 DOI: 10.1002/glia.24384] [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: 01/31/2023] [Revised: 04/28/2023] [Accepted: 05/02/2023] [Indexed: 05/16/2023]
Abstract
Astrocytes are wired to bidirectionally communicate with neurons namely with synapses, thus shaping synaptic plasticity, which in the hippocampus is considered to underlie learning and memory. Adenosine A2A receptors (A2A R) are a potential candidate to modulate this bidirectional communication, since A2A R regulate synaptic plasticity and memory and also control key astrocytic functions. Nonetheless, little is known about the role of astrocytic A2A R in synaptic plasticity and hippocampal-dependent memory. Here, we investigated the impact of genetic silencing astrocytic A2A R on hippocampal synaptic plasticity and memory of adult mice. The genetic A2A R silencing in astrocytes was accomplished by a bilateral injection into the CA1 hippocampal area of a viral construct (AAV5-GFAP-GFP-Cre) that inactivate A2A R expression in astrocytes of male adult mice carrying "floxed" A2A R gene, as confirmed by A2A R binding assays. Astrocytic A2A R silencing alters astrocytic morphology, typified by an increment of astrocytic arbor complexity, and led to deficits in spatial reference memory and compromised hippocampal synaptic plasticity, typified by a reduction of LTP magnitude and a shift of synaptic long-term depression (LTD) toward LTP. These data indicate that astrocytic A2A R control astrocytic morphology and influence hippocampal synaptic plasticity and memory of adult mice in a manner different from neuronal A2A R.
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Affiliation(s)
- Daniela Madeira
- Faculty of Medicine, University of Coimbra (FMUC), Coimbra, Portugal
- Center for Neuroscience and Cell Biology- University of Coimbra (CNC- UC), Coimbra, Portugal
| | - Cátia R Lopes
- Faculty of Medicine, University of Coimbra (FMUC), Coimbra, Portugal
- Center for Neuroscience and Cell Biology- University of Coimbra (CNC- UC), Coimbra, Portugal
| | - Ana P Simões
- Center for Neuroscience and Cell Biology- University of Coimbra (CNC- UC), Coimbra, Portugal
| | - Paula M Canas
- Center for Neuroscience and Cell Biology- University of Coimbra (CNC- UC), Coimbra, Portugal
| | - Rodrigo A Cunha
- Faculty of Medicine, University of Coimbra (FMUC), Coimbra, Portugal
- Center for Neuroscience and Cell Biology- University of Coimbra (CNC- UC), Coimbra, Portugal
| | - Paula Agostinho
- Faculty of Medicine, University of Coimbra (FMUC), Coimbra, Portugal
- Center for Neuroscience and Cell Biology- University of Coimbra (CNC- UC), Coimbra, Portugal
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3
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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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4
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Adenosine A 2A receptor neurons in the olfactory bulb mediate odor-guided behaviors in mice. Brain Res 2021; 1768:147590. [PMID: 34310936 DOI: 10.1016/j.brainres.2021.147590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 07/09/2021] [Accepted: 07/21/2021] [Indexed: 11/21/2022]
Abstract
Depression, rapid eye movement (REM) sleep behavior disorder, and altered olfaction are often present in Parkinson's disease. Our previous studies demonstrated the role of the olfactory bulb (OB) in causing REM sleep disturbances in depression. Furthermore, adenosine A2A receptors (A2AR) which are richly expressed in the OB, play an important role in the regulation of REM sleep. Caffeine, an adenosine A1 receptors and A2AR antagonist, and other A2AR antagonists were reported to improve olfactory function and restore age-related olfactory deficits. Therefore, we hypothesized that the A2AR neurons in the OB may regulate olfaction or odor-guided behaviors in mice. In the present study, we employed chemogenetics to specifically activate or inhibit neuronal activity. Then, buried food test and olfactory habituation/dishabituation test were performed to measure the changes in the mice's olfactory ability. We demonstrated that activation of OB neurons or OB A2AR neurons shortened the latency of buried food test and enhanced olfactory habituation to the same odors and dishabituation to different odors; inhibition of these neurons showed the opposite effects. Photostimulation of ChR2-expressing OB A2AR neuron terminals evoked inward current in the olfactory tubercle (OT) and the piriform cortex (Pir), which was blocked by glutamate receptor antagonists 2-amino-5-phosphonopentanoic acid and 6-cyano-7nitroquinoxaline-2,3-dione. Collectively, these results suggest that the OB mediates olfaction via A2AR neurons in mice. Moreover, the excitatory glutamatergic release from OB neurons to the OT and the Pir were found responsible for the olfaction-mediated effects of OB A2AR neurons.
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Manzini I, Schild D, Di Natale C. Principles of odor coding in vertebrates and artificial chemosensory systems. Physiol Rev 2021; 102:61-154. [PMID: 34254835 DOI: 10.1152/physrev.00036.2020] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The biological olfactory system is the sensory system responsible for the detection of the chemical composition of the environment. Several attempts to mimic biological olfactory systems have led to various artificial olfactory systems using different technical approaches. Here we provide a parallel description of biological olfactory systems and their technical counterparts. We start with a presentation of the input to the systems, the stimuli, and treat the interface between the external world and the environment where receptor neurons or artificial chemosensors reside. We then delineate the functions of receptor neurons and chemosensors as well as their overall I-O relationships. Up to this point, our account of the systems goes along similar lines. The next processing steps differ considerably: while in biology the processing step following the receptor neurons is the "integration" and "processing" of receptor neuron outputs in the olfactory bulb, this step has various realizations in electronic noses. For a long period of time, the signal processing stages beyond the olfactory bulb, i.e., the higher olfactory centers were little studied. Only recently there has been a marked growth of studies tackling the information processing in these centers. In electronic noses, a third stage of processing has virtually never been considered. In this review, we provide an up-to-date overview of the current knowledge of both fields and, for the first time, attempt to tie them together. We hope it will be a breeding ground for better information, communication, and data exchange between very related but so far little connected fields.
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Affiliation(s)
- Ivan Manzini
- Animal Physiology and Molecular Biomedicine, Justus-Liebig-University Gießen, Gießen, Germany
| | - Detlev Schild
- Institute of Neurophysiology and Cellular Biophysics, University Medical Center, University of Göttingen, Göttingen, Germany
| | - Corrado Di Natale
- Department of Electronic Engineering, University of Rome Tor Vergata, Rome, Italy
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6
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Lohr C, Beiersdorfer A, Fischer T, Hirnet D, Rotermund N, Sauer J, Schulz K, Gee CE. Using Genetically Encoded Calcium Indicators to Study Astrocyte Physiology: A Field Guide. Front Cell Neurosci 2021; 15:690147. [PMID: 34177468 PMCID: PMC8226001 DOI: 10.3389/fncel.2021.690147] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 05/06/2021] [Indexed: 01/14/2023] Open
Abstract
Ca2+ imaging is the most frequently used technique to study glial cell physiology. While chemical Ca2+ indicators served to visualize and measure changes in glial cell cytosolic Ca2+ concentration for several decades, genetically encoded Ca2+ indicators (GECIs) have become state of the art in recent years. Great improvements have been made since the development of the first GECI and a large number of GECIs with different physical properties exist, rendering it difficult to select the optimal Ca2+ indicator. This review discusses some of the most frequently used GECIs and their suitability for glial cell research.
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Affiliation(s)
- Christian Lohr
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | | | - Timo Fischer
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Daniela Hirnet
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Natalie Rotermund
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Jessica Sauer
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Kristina Schulz
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Christine E Gee
- Institute of Synaptic Physiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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7
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Fischer T, Prey J, Eschholz L, Rotermund N, Lohr C. Norepinephrine-Induced Calcium Signaling and Store-Operated Calcium Entry in Olfactory Bulb Astrocytes. Front Cell Neurosci 2021; 15:639754. [PMID: 33833669 PMCID: PMC8021869 DOI: 10.3389/fncel.2021.639754] [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: 12/09/2020] [Accepted: 03/02/2021] [Indexed: 11/30/2022] Open
Abstract
It is well-established that astrocytes respond to norepinephrine with cytosolic calcium rises in various brain areas, such as hippocampus or neocortex. However, less is known about the effect of norepinephrine on olfactory bulb astrocytes. In the present study, we used confocal calcium imaging and immunohistochemistry in mouse brain slices of the olfactory bulb, a brain region with a dense innervation of noradrenergic fibers, to investigate the calcium signaling evoked by norepinephrine in astrocytes. Our results show that application of norepinephrine leads to a cytosolic calcium rise in astrocytes which is independent of neuronal activity and mainly mediated by PLC/IP3-dependent internal calcium release. In addition, store-operated calcium entry (SOCE) contributes to the late phase of the response. Antagonists of both α1- and α2-adrenergic receptors, but not β-receptors, largely reduce the adrenergic calcium response, indicating that both α-receptor subtypes mediate norepinephrine-induced calcium transients in olfactory bulb astrocytes, whereas β-receptors do not contribute to the calcium transients.
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Affiliation(s)
- Timo Fischer
- Division of Neurophysiology, Department of Biology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Jessica Prey
- Division of Neurophysiology, Department of Biology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Lena Eschholz
- Division of Neurophysiology, Department of Biology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Natalie Rotermund
- Division of Neurophysiology, Department of Biology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Christian Lohr
- Division of Neurophysiology, Department of Biology, Institute of Zoology, University of Hamburg, Hamburg, Germany
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8
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Klein M, Lohr C, Droste D. Age-Dependent Heterogeneity of Murine Olfactory Bulb Astrocytes. Front Aging Neurosci 2020; 12:172. [PMID: 32581775 PMCID: PMC7296154 DOI: 10.3389/fnagi.2020.00172] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 05/18/2020] [Indexed: 12/15/2022] Open
Abstract
Astrocytes have a high impact on the structure of the central nervous system, as they control neural activity, development, and plasticity. Heterogeneity of astrocytes has been shown before, but so far only a few studies have demonstrated heterogeneous morphology of astrocytes concerning aging. In this study, we examined morphologic differences of astrocyte subpopulations in adult mice and the progression of these differences with age. We surveyed astrocytes in olfactory bulb slices of mice aged 3 months, 1 year and 2 years (three animals each age group), based on their appearance in anti-GFAP immunostaining. Based on this data we established three different types of astrocytes: type I (stellate), type II (elliptic), and type III (squid-like). We found that with the advanced age of the mice, astrocytes grow in size and complexity. Major changes occurred between the ages of 3 months and 1 year, while between 1 and 2 years no significant development in cell size and complexity could be detected. Our results show that astrocytes in the olfactory bulb are heterogeneous and undergo morphological transformation until late adolescence but not upon senescence. Structural plasticity is further substantiated by the expression of vimentin in some astrocyte processes in all age groups.
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Affiliation(s)
- Marcel Klein
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Christian Lohr
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Damian Droste
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
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9
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Kofuji P, Araque A. G-Protein-Coupled Receptors in Astrocyte-Neuron Communication. Neuroscience 2020; 456:71-84. [PMID: 32224231 DOI: 10.1016/j.neuroscience.2020.03.025] [Citation(s) in RCA: 117] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 03/13/2020] [Accepted: 03/18/2020] [Indexed: 12/11/2022]
Abstract
Astrocytes, a major type of glial cell, are known to play key supportive roles in brain function, contributing to ion and neurotransmitter homeostasis, maintaining the blood-brain barrier and providing trophic and metabolic support for neurons. Besides these support functions, astrocytes are emerging as important elements in brain physiology through signaling exchange with neurons at tripartite synapses. Astrocytes express a wide variety of neurotransmitter transporters and receptors that allow them to sense and respond to synaptic activity. Principal among them are the G-protein-coupled receptors (GPCRs) in astrocytes because their activation by synaptically released neurotransmitters leads to mobilization of intracellular calcium. In turn, activated astrocytes release neuroactive substances called gliotransmitters, such as glutamate, GABA, and ATP/adenosine that lead to synaptic regulation through activation of neuronal GPCRs. In this review we will present and discuss recent evidence demonstrating the critical roles played by GPCRs in the bidirectional astrocyte-neuron signaling, and their crucial involvement in the astrocyte-mediated regulation of synaptic transmission and plasticity.
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Affiliation(s)
- Paulo Kofuji
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Alfonso Araque
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA.
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10
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Dopamine-induced calcium signaling in olfactory bulb astrocytes. Sci Rep 2020; 10:631. [PMID: 31959788 PMCID: PMC6971274 DOI: 10.1038/s41598-020-57462-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 12/30/2019] [Indexed: 11/08/2022] Open
Abstract
It is well established that astrocytes respond to the major neurotransmitters glutamate and GABA with cytosolic calcium rises, whereas less is known about the effect of dopamine on astroglial cells. In the present study, we used confocal calcium imaging in mouse brain slices of the olfactory bulb, a brain region with a large population of dopaminergic neurons, to investigate calcium signaling evoked by dopamine in astrocytes. Our results show that application of dopamine leads to a dose-dependent cytosolic calcium rise in astrocytes (EC50 = 76 µM) which is independent of neuronal activity and mainly mediated by PLC/IP3-dependent internal calcium release. Antagonists of both D1- and D2-class dopamine receptors partly reduce the dopaminergic calcium response, indicating that both receptor classes contribute to dopamine-induced calcium transients in olfactory bulb astrocytes.
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11
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Beiersdorfer A, Wolburg H, Grawe J, Scheller A, Kirchhoff F, Lohr C. Sublamina-specific organization of the blood brain barrier in the mouse olfactory nerve layer. Glia 2019; 68:631-645. [PMID: 31696993 DOI: 10.1002/glia.23744] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 10/17/2019] [Accepted: 10/18/2019] [Indexed: 01/19/2023]
Abstract
Astrocytes constitute the main glial component of the mammalian blood brain barrier (BBB). However, in the olfactory bulb (OB), the olfactory nerve layer (ONL) is almost devoid of astrocytes, raising the question which glial cells are part of the BBB. We used mice expressing EGFP in astrocytes and tdTomato in olfactory ensheathing cells (OECs), a specialized type of glial cells in the ONL, to unequivocally identify both glial cell types and investigate their contribution to the BBB in the olfactory bulb. OECs were located exclusively in the ONL, while somata of astrocytes were located in deeper layers and extended processes in the inner sublamina of the ONL. These processes surrounded blood vessels and contained aquaporin-4, an astrocytic protein enriched at the BBB. In the outer sublamina of the ONL, in contrast, blood vessels were surrounded by aquaporin-4-negative processes of OECs. Transcardial perfusion of blood vessels with lanthanum and subsequent visualization by electron microscopy showed that blood vessels enwrapped by OECs possessed intact tight junctions. In acute olfactory bulb preparations, injection of fluorescent glucose 6-NBDG into blood vessels resulted in labeling of OECs, indicating glucose transport from the perivascular space into OECs. In addition, Ca2+ transients in OECs in the outer sublamina evoked vasoconstriction, whereas Ca2+ signaling in OECs of the inner sublamina had no effect on adjacent blood vessels. Our results demonstrate that the BBB in the inner sublamina of the ONL contains astrocytes, while in the outer ONL OECs are part of the BBB.
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Affiliation(s)
| | - Hartwig Wolburg
- Institute of Pathology and Neuropathology, University of Tübingen, Tübingen, Germany
| | - Janine Grawe
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Anja Scheller
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Christian Lohr
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
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12
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Verkhratsky A, Parpura V, Vardjan N, Zorec R. Physiology of Astroglia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1175:45-91. [PMID: 31583584 DOI: 10.1007/978-981-13-9913-8_3] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Astrocytes are principal cells responsible for maintaining the brain homeostasis. Additionally, these glial cells are also involved in homocellular (astrocyte-astrocyte) and heterocellular (astrocyte-other cell types) signalling and metabolism. These astroglial functions require an expression of the assortment of molecules, be that transporters or pumps, to maintain ion concentration gradients across the plasmalemma and the membrane of the endoplasmic reticulum. Astrocytes sense and balance their neurochemical environment via variety of transmitter receptors and transporters. As they are electrically non-excitable, astrocytes display intracellular calcium and sodium fluctuations, which are not only used for operative signalling but can also affect metabolism. In this chapter we discuss the molecules that achieve ionic gradients and underlie astrocyte signalling.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK. .,Faculty of Health and Medical Sciences, Center for Basic and Translational Neuroscience, University of Copenhagen, 2200, Copenhagen, Denmark. .,Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain.
| | - Vladimir Parpura
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Nina Vardjan
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Celica Biomedical, Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Celica Biomedical, Ljubljana, Slovenia
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13
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Rotermund N, Schulz K, Hirnet D, Lohr C. Purinergic Signaling in the Vertebrate Olfactory System. Front Cell Neurosci 2019; 13:112. [PMID: 31057369 PMCID: PMC6477478 DOI: 10.3389/fncel.2019.00112] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 03/07/2019] [Indexed: 12/15/2022] Open
Abstract
Adenosine 5'-triphosphate (ATP) is an ubiquitous co-transmitter in the vertebrate brain. ATP itself, as well as its breakdown products ADP and adenosine are involved in synaptic transmission and plasticity, neuron-glia communication and neural development. Although purinoceptors have been demonstrated in the vertebrate olfactory system by means of histological techniques for many years, detailed insights into physiological properties and functional significance of purinergic signaling in olfaction have been published only recently. We review the current literature on purinergic neuromodulation, neuron-glia interactions and neurogenesis in the vertebrate olfactory system.
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Affiliation(s)
- Natalie Rotermund
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Kristina Schulz
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Daniela Hirnet
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Christian Lohr
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
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14
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Beiersdorfer A, Scheller A, Kirchhoff F, Lohr C. Panglial gap junctions between astrocytes and olfactory ensheathing cells mediate transmission of Ca 2+ transients and neurovascular coupling. Glia 2019; 67:1385-1400. [PMID: 30883940 DOI: 10.1002/glia.23613] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 02/22/2019] [Accepted: 02/25/2019] [Indexed: 12/13/2022]
Abstract
Astrocytes are arranged in highly organized gap junction-coupled networks, communicating via the propagation of Ca2+ waves. Astrocytes are gap junction-coupled not only to neighboring astrocytes, but also to oligodendrocytes, forming so-called panglial syncytia. It is not known, however, whether glial cells in panglial syncytia transmit information using Ca2+ signaling. We used confocal Ca2+ imaging to study intercellular communication between astrocytes and olfactory ensheathing glial cells (OECs) in in-toto preparations of the mouse olfactory bulb. Our results demonstrate that Ca2+ transients in juxtaglomerular astrocytes, evoked by local photolysis of "caged" ATP and "caged" tACPD, led to subsequent Ca2+ responses in OECs. This transmission of Ca2+ responses from astrocytes to OECs persisted in the presence of neuronal inhibition, but was absent when gap junctional coupling was suppressed with carbenoxolone. When Ca2+ transients were directly evoked in OECs by puff application of DHPG, they resulted in delayed Ca2+ responses in juxtaglomerular astrocytes, indicating that panglial transmission of Ca2+ signals occurred in a bidirectional manner. In addition, panglial transmission of Ca2+ signals from astrocytes to OECs resulted in vasoconstriction of OEC-associated blood vessels in the olfactory nerve layer. Our results demonstrate functional transmission of Ca2+ signals between different classes of glial cells within gap junction-coupled panglial networks and the resulting regulation of blood vessel diameter in the olfactory bulb.
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Affiliation(s)
| | - Anja Scheller
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Christian Lohr
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
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15
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Adenine nucleotides as paracrine mediators and intracellular second messengers in immunity and inflammation. Biochem Soc Trans 2019; 47:329-337. [PMID: 30674608 DOI: 10.1042/bst20180419] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 12/19/2018] [Accepted: 12/20/2018] [Indexed: 02/06/2023]
Abstract
Adenine nucleotides (AdNs) play important roles in immunity and inflammation. Extracellular AdNs, such as adenosine triphosphate (ATP) or nicotinamide adenine dinucleotide (NAD) and their metabolites, act as paracrine messengers by fine-tuning both pro- and anti-inflammatory processes. Moreover, intracellular AdNs derived from ATP or NAD play important roles in many cells of the immune system, including T lymphocytes, macrophages, neutrophils and others. These intracellular AdNs are signaling molecules that transduce incoming signals into meaningful cellular responses, e.g. activation of immune responses against pathogens.
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Stefanello N, Spanevello RM, Passamonti S, Porciúncula L, Bonan CD, Olabiyi AA, Teixeira da Rocha JB, Assmann CE, Morsch VM, Schetinger MRC. Coffee, caffeine, chlorogenic acid, and the purinergic system. Food Chem Toxicol 2018; 123:298-313. [PMID: 30291944 DOI: 10.1016/j.fct.2018.10.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 09/29/2018] [Accepted: 10/02/2018] [Indexed: 12/14/2022]
Abstract
Coffee is a drink prepared from roasted coffee beans and is lauded for its aroma and flavour. It is the third most popular beverage in the world. This beverage is known by its stimulant effect associated with the presence of methylxanthines. Caffeine, a purine-like molecule (1,3,7 trymetylxantine), is the most important bioactive compound in coffee, among others such as chlorogenic acid (CGA), diterpenes, and trigonelline. CGA is a phenolic acid with biological properties as antioxidant, anti-inflammatory, neuroprotector, hypolipidemic, and hypoglicemic. Purinergic system plays a key role inneuromodulation and homeostasis. Extracellular ATP, other nucleotides and adenosine are signalling molecules that act through their specific receptors, namely purinoceptors, P1 for nucleosides and P2 for nucleotides. They regulate many pathological processes, since adenosine, for instance, can limit the damage caused by ATP in the excitotoxicity from the neuronal cells. The primary purpose of this review is to discuss the effects of coffee, caffeine, and CGA on the purinergic system. This review focuses on the relationship/interplay between coffee, caffeine, CGA, and adenosine, and their effects on ectonucleotidases activities as well as on the modulation of P1 and P2 receptors from central nervous system and also in peripheral tissue.
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Affiliation(s)
- Naiara Stefanello
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, UFSM, Camobi, 97105-900, Santa Maria, RS, Brazil.
| | - Roselia Maria Spanevello
- Programa de Pós Graduação em Bioquímica e Bioprospecção: Centro de Ciências Farmacêuticas, Químicas e de Alimentos, UFPel, Campus Capão do Leão 96010-900, Pelotas, RS, Brazil
| | - Sabina Passamonti
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, via L. Giorgieri 1, 34127, Trieste, Italy
| | - Lisiane Porciúncula
- Departamento de Bioquímica, UFRGS, 90040-060, Porto Alegre, Rio Grande do Sul, Brazil
| | - Carla Denise Bonan
- Programa de Pós-graduação em Biologia Celular e Molecular Faculdade de Biociências da Pontifícia Universidade Católica do Rio Grande do Sul, PUCRS, Porto Alegre, RS, Brazil
| | | | - João Batista Teixeira da Rocha
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, UFSM, Camobi, 97105-900, Santa Maria, RS, Brazil
| | - Charles Elias Assmann
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, UFSM, Camobi, 97105-900, Santa Maria, RS, Brazil
| | - Vera Maria Morsch
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, UFSM, Camobi, 97105-900, Santa Maria, RS, Brazil
| | - Maria Rosa Chitolina Schetinger
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, UFSM, Camobi, 97105-900, Santa Maria, RS, Brazil.
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17
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Rotermund N, Winandy S, Fischer T, Schulz K, Fregin T, Alstedt N, Buchta M, Bartels J, Carlström M, Lohr C, Hirnet D. Adenosine A 1 receptor activates background potassium channels and modulates information processing in olfactory bulb mitral cells. J Physiol 2018; 596:717-733. [PMID: 29274133 DOI: 10.1113/jp275503] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 12/07/2017] [Indexed: 12/20/2022] Open
Abstract
KEY POINTS Adenosine is a widespread neuromodulator in the mammalian brain, but whether it affects information processing in sensory system(s) remains largely unknown. Here we show that adenosine A1 receptors hyperpolarize mitral cells, one class of principal neurons that propagate odour information from the olfactory bulb to higher brain areas, by activation of background K+ channels. The adenosine-modulated background K+ channels belong to the family of two-pore domain K+ channels. Adenosine reduces spontaneous activity of mitral cells, whereas action potential firing evoked by synaptic input upon stimulation of sensory neurons is not affected, resulting in a higher ratio of evoked firing (signal) over spontaneous firing (noise) and hence an improved signal-to-noise ratio. The study shows for the first time that adenosine influences fine-tuning of the input-output relationship in sensory systems. ABSTRACT Neuromodulation by adenosine is of critical importance in many brain regions, but the role of adenosine in olfactory information processing has not been studied so far. We investigated the effects of adenosine on mitral cells, which are projection neurons of the olfactory bulb. Significant expression of A1 and A2A receptors was found in mitral cells, as demonstrated by in situ hybridization. Application of adenosine in acute olfactory bulb slices hyperpolarized mitral cells in wild-type but not in adenosine A1 receptor knockout mice. Adenosine-induced hyperpolarization was mediated by background K+ currents that were reduced by halothane and bupivacaine, which are known to inhibit two-pore domain K+ (K2P) channels. In mitral cells, electrical stimulation of axons of olfactory sensory neurons evoked synaptic currents, which can be considered as input signals, while spontaneous firing independent of sensory input can be considered as noise. Synaptic currents were not affected by adenosine, while adenosine reduced spontaneous firing, leading to an increase in the signal-to-noise ratio of mitral cell firing. Our findings demonstrate that A1 adenosine receptors activate two-pore domain K+ channels, which increases the signal-to-noise ratio of the input-output relationship in mitral cells and thereby modulates information processing in the olfactory bulb.
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Affiliation(s)
- Natalie Rotermund
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Martin-Luther-King-Platz 3, Hamburg, 20146, Germany
| | - Svenja Winandy
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Martin-Luther-King-Platz 3, Hamburg, 20146, Germany
| | - Timo Fischer
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Martin-Luther-King-Platz 3, Hamburg, 20146, Germany
| | - Kristina Schulz
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Martin-Luther-King-Platz 3, Hamburg, 20146, Germany
| | - Torsten Fregin
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Martin-Luther-King-Platz 3, Hamburg, 20146, Germany
| | - Nadine Alstedt
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Martin-Luther-King-Platz 3, Hamburg, 20146, Germany
| | - Melanie Buchta
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Martin-Luther-King-Platz 3, Hamburg, 20146, Germany
| | - Janick Bartels
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Martin-Luther-King-Platz 3, Hamburg, 20146, Germany
| | - Mattias Carlström
- Department of Physiology and Pharmacology, Karolinska Institutet, Nanna Svartz Väg 2, Stockholm, 17177, Sweden
| | - Christian Lohr
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Martin-Luther-King-Platz 3, Hamburg, 20146, Germany
| | - Daniela Hirnet
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Martin-Luther-King-Platz 3, Hamburg, 20146, Germany
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18
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Schulz K, Rotermund N, Grzelka K, Benz J, Lohr C, Hirnet D. Adenosine A 1 Receptor-Mediated Attenuation of Reciprocal Dendro-Dendritic Inhibition in the Mouse Olfactory Bulb. Front Cell Neurosci 2018; 11:435. [PMID: 29379418 PMCID: PMC5775233 DOI: 10.3389/fncel.2017.00435] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 12/26/2017] [Indexed: 12/14/2022] Open
Abstract
It is well described that A1 adenosine receptors inhibit synaptic transmission at excitatory synapses in the brain, but the effect of adenosine on reciprocal synapses has not been studied so far. In the olfactory bulb, the majority of synapses are reciprocal dendro-dendritic synapses mediating recurrent inhibition. We studied the effect of A1 receptor activation on recurrent dendro-dendritic inhibition in mitral cells using whole-cell patch-clamp recordings. Adenosine reduced dendro-dendritic inhibition in wild-type, but not in A1 receptor knock-out mice. Both NMDA receptor-mediated and AMPA receptor-mediated dendro-dendritic inhibition were attenuated by adenosine, indicating that reciprocal synapses between mitral cells and granule cells as well as parvalbumin interneurons were targeted by A1 receptors. Adenosine reduced glutamatergic self-excitation and inhibited N-type and P/Q-type calcium currents, but not L-type calcium currents in mitral cells. Attenuated glutamate release, due to A1 receptor-mediated calcium channel inhibition, resulted in impaired dendro-dendritic inhibition. In behavioral tests we tested the ability of wild-type and A1 receptor knock-out mice to find a hidden piece of food. Knock-out mice were significantly faster in locating the food. Our results indicate that A1 adenosine receptors attenuates dendro-dendritic reciprocal inhibition and suggest that they affect odor information processing.
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Affiliation(s)
- Kristina Schulz
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Natalie Rotermund
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Katarzyna Grzelka
- Department of Physiology and Pathophysiology, Medical University of Warsaw, Warsaw, Poland
| | - Jan Benz
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Christian Lohr
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Daniela Hirnet
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Hamburg, Germany
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Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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20
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Verkhratsky A, Nedergaard M. Physiology of Astroglia. Physiol Rev 2018; 98:239-389. [PMID: 29351512 PMCID: PMC6050349 DOI: 10.1152/physrev.00042.2016] [Citation(s) in RCA: 885] [Impact Index Per Article: 147.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/22/2017] [Accepted: 04/27/2017] [Indexed: 02/07/2023] Open
Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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21
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Daumas-Meyer V, Champeil-Potokar G, Chaumontet C, Dahirel P, Papillon C, Congar P, Denis I. Fasting induces astroglial plasticity in the olfactory bulb glomeruli of rats. Glia 2017; 66:762-776. [DOI: 10.1002/glia.23280] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 11/22/2017] [Accepted: 11/24/2017] [Indexed: 01/20/2023]
Affiliation(s)
| | | | | | - Patrice Dahirel
- NBO UR1197, INRA, Université Paris-Saclay; Jouy-en-Josas 78350 France
| | | | - Patrice Congar
- NBO UR1197, INRA, Université Paris-Saclay; Jouy-en-Josas 78350 France
| | - Isabelle Denis
- NBO UR1197, INRA, Université Paris-Saclay; Jouy-en-Josas 78350 France
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22
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Lind BL, Jessen SB, Lønstrup M, Joséphine C, Bonvento G, Lauritzen M. Fast Ca 2+ responses in astrocyte end-feet and neurovascular coupling in mice. Glia 2017; 66:348-358. [PMID: 29058353 DOI: 10.1002/glia.23246] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 09/28/2017] [Accepted: 09/29/2017] [Indexed: 01/09/2023]
Abstract
Cerebral blood flow (CBF) is regulated by the activity of neurons and astrocytes. Understanding how these cells control activity-dependent increases in CBF is crucial to interpreting functional neuroimaging signals. The relative importance of neurons and astrocytes is debated, as are the functional implications of fast Ca2+ changes in astrocytes versus neurons. Here, we used two-photon microscopy to assess Ca2+ changes in neuropil, astrocyte processes, and astrocyte end-feet in response to whisker pad stimulation in mice. We also developed a pixel-based analysis to improve the detection of rapid Ca2+ signals in the subcellular compartments of astrocytes. Fast Ca2+ responses were observed using both chemical and genetically encoded Ca2+ indicators in astrocyte end-feet prior to dilation of arterioles and capillaries. A low dose of the NMDA receptor antagonist (5R,10s)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine-hydrogen-maleate (MK801) attenuated fast Ca2+ responses in the neuropil and astrocyte processes, but not in astrocyte end-feet, and the evoked CBF response was preserved. In addition, a low dose of 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP), an agonist for the extrasynaptic GABAA receptor (GABAA R), increased CBF responses and the fast Ca2+ response in astrocyte end-feet but did not affect Ca2+ responses in astrocyte processes and neuropil. These results suggest that fast Ca2+ increases in the neuropil and astrocyte processes are not necessary for an evoked CBF response. In contrast, as local fast Ca2+ responses in astrocyte end-feet are unaffected by MK801 but increase via GABAA R-dependent mechanisms that also increased CBF responses, we hypothesize that the fast Ca2+ increases in end-feet adjust CBF during synaptic activity.
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Affiliation(s)
- Barbara Lykke Lind
- Department of Neuroscience and Center for Healthy Aging, University of Copenhagen, Denmark
| | - Sanne Barsballe Jessen
- Department of Neuroscience and Center for Healthy Aging, University of Copenhagen, Denmark
| | - Micael Lønstrup
- Department of Neuroscience and Center for Healthy Aging, University of Copenhagen, Denmark
| | - Charlène Joséphine
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Département de la Recherche Fondamentale (DRF), Institut de Biologie François-Jacob, Molecular Imaging Research Center (MIRCen), CNRS UMR 9199, Université Paris-Sud, Université Paris-Saclay, Fontenay-aux-Roses, France
| | - Gilles Bonvento
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Département de la Recherche Fondamentale (DRF), Institut de Biologie François-Jacob, Molecular Imaging Research Center (MIRCen), CNRS UMR 9199, Université Paris-Sud, Université Paris-Saclay, Fontenay-aux-Roses, France
| | - Martin Lauritzen
- Department of Neuroscience and Center for Healthy Aging, University of Copenhagen, Denmark.,Department of Clinical Neurophysiology, Glostrup Hospital, Denmark
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23
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Ca 2+-permeable AMPA receptors in mouse olfactory bulb astrocytes. Sci Rep 2017; 7:44817. [PMID: 28322255 PMCID: PMC5359673 DOI: 10.1038/srep44817] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 02/15/2017] [Indexed: 02/06/2023] Open
Abstract
Ca2+ signaling in astrocytes is considered to be mainly mediated by metabotropic receptors linked to intracellular Ca2+ release. However, recent studies demonstrate a significant contribution of Ca2+ influx to spontaneous and evoked Ca2+ signaling in astrocytes, suggesting that Ca2+ influx might account for astrocytic Ca2+ signaling to a greater extent than previously thought. Here, we investigated AMPA-evoked Ca2+ influx into olfactory bulb astrocytes in mouse brain slices using Fluo-4 and GCaMP6s, respectively. Bath application of AMPA evoked Ca2+ transients in periglomerular astrocytes that persisted after neuronal transmitter release was inhibited by tetrodotoxin and bafilomycin A1. Withdrawal of external Ca2+ suppressed AMPA-evoked Ca2+ transients, whereas depletion of Ca2+ stores had no effect. Both Ca2+ transients and inward currents induced by AMPA receptor activation were partly reduced by Naspm, a blocker of Ca2+-permeable AMPA receptors lacking the GluA2 subunit. Antibody staining revealed a strong expression of GluA1 and GluA4 and a weak expression of GluA2 in periglomerular astrocytes. Our results indicate that Naspm-sensitive, Ca2+-permeable AMPA receptors contribute to Ca2+ signaling in periglomerular astrocytes in the olfactory bulb.
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24
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Adenosine A2A receptors in the olfactory bulb suppress rapid eye movement sleep in rodents. Brain Struct Funct 2016; 222:1351-1366. [DOI: 10.1007/s00429-016-1281-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 07/26/2016] [Indexed: 12/25/2022]
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25
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Liu Y, Zou H, Zhao P, Sun B, Wang J, Kong Q, Mu L, Zhao S, Wang G, Wang D, Zhang Y, Zhao J, Yin P, Liu L, Zhao X, Li H. Activation of the adenosine A2A receptor attenuates experimental autoimmune encephalomyelitis and is associated with increased intracellular calcium levels. Neuroscience 2016; 330:150-61. [DOI: 10.1016/j.neuroscience.2016.05.028] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 05/12/2016] [Accepted: 05/13/2016] [Indexed: 02/01/2023]
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26
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Vincis R, Lagier S, Van De Ville D, Rodriguez I, Carleton A. Sensory-Evoked Intrinsic Imaging Signals in the Olfactory Bulb Are Independent of Neurovascular Coupling. Cell Rep 2015; 12:313-25. [PMID: 26146075 PMCID: PMC5066842 DOI: 10.1016/j.celrep.2015.06.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 05/12/2015] [Accepted: 06/03/2015] [Indexed: 11/19/2022] Open
Abstract
Functional brain-imaging techniques used in humans and animals, such as functional MRI and intrinsic optical signal (IOS) imaging, are thought to largely rely on neurovascular coupling and hemodynamic responses. Here, taking advantage of the well-described micro-architecture of the mouse olfactory bulb, we dissected the nature of odor-evoked IOSs. Using in vivo pharmacology in transgenic mouse lines reporting activity in different cell types, we show that parenchymal IOSs are largely independent of neurotransmitter release and neurovascular coupling. Furthermore, our results suggest that odor-evoked parenchymal IOSs originate from changes in light scattering of olfactory sensory neuron axons, mostly due to water movement following action potential propagation. Our study sheds light on a direct correlate of neuronal activity, which may be used for large-scale functional brain imaging.
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Affiliation(s)
- Roberto Vincis
- Department of Basic Neurosciences, School of Medicine, University of Geneva, 1211 Geneva, Switzerland; Geneva Neuroscience Center, University of Geneva, 1211 Geneva, Switzerland
| | - Samuel Lagier
- Department of Basic Neurosciences, School of Medicine, University of Geneva, 1211 Geneva, Switzerland; Geneva Neuroscience Center, University of Geneva, 1211 Geneva, Switzerland
| | - Dimitri Van De Ville
- Geneva Neuroscience Center, University of Geneva, 1211 Geneva, Switzerland; Department of Radiology and Medical Informatics, University of Geneva, 1211 Geneva, Switzerland; Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Ivan Rodriguez
- Geneva Neuroscience Center, University of Geneva, 1211 Geneva, Switzerland; Department of Genetics and Evolution, University of Geneva, 1211 Geneva, Switzerland.
| | - Alan Carleton
- Department of Basic Neurosciences, School of Medicine, University of Geneva, 1211 Geneva, Switzerland; Geneva Neuroscience Center, University of Geneva, 1211 Geneva, Switzerland.
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27
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Rodrigues RJ, Tomé AR, Cunha RA. ATP as a multi-target danger signal in the brain. Front Neurosci 2015; 9:148. [PMID: 25972780 PMCID: PMC4412015 DOI: 10.3389/fnins.2015.00148] [Citation(s) in RCA: 185] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 04/10/2015] [Indexed: 12/13/2022] Open
Abstract
ATP is released in an activity-dependent manner from different cell types in the brain, fulfilling different roles as a neurotransmitter, neuromodulator, in astrocyte-to-neuron communication, propagating astrocytic responses and formatting microglia responses. This involves the activation of different ATP P2 receptors (P2R) as well as adenosine receptors upon extracellular ATP catabolism by ecto-nucleotidases. Notably, brain noxious stimuli trigger a sustained increase of extracellular ATP, which plays a key role as danger signal in the brain. This involves a combined action of extracellular ATP in different cell types, namely increasing the susceptibility of neurons to damage, promoting astrogliosis and recruiting and formatting microglia to mount neuroinflammatory responses. Such actions involve the activation of different receptors, as heralded by neuroprotective effects resulting from blockade mainly of P2X7R, P2Y1R and adenosine A2A receptors (A2AR), which hierarchy, cooperation and/or redundancy is still not resolved. These pleiotropic functions of ATP as a danger signal in brain damage prompt a therapeutic interest to multi-target different purinergic receptors to provide maximal opportunities for neuroprotection.
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Affiliation(s)
- Ricardo J Rodrigues
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra Coimbra, Portugal ; Institute for Interdisciplinary Research, University of Coimbra Coimbra, Portugal
| | - Angelo R Tomé
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra Coimbra, Portugal ; Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra Coimbra, Portugal
| | - Rodrigo A Cunha
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra Coimbra, Portugal ; Faculty of Medicine, University of Coimbra Coimbra, Portugal
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28
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Irwin M, Greig A, Tvrdik P, Lucero MT. PACAP modulation of calcium ion activity in developing granule cells of the neonatal mouse olfactory bulb. J Neurophysiol 2014; 113:1234-48. [PMID: 25475351 DOI: 10.1152/jn.00594.2014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ca(2+) activity in the CNS is critical for the establishment of developing neuronal circuitry prior to and during early sensory input. In developing olfactory bulb (OB), the neuromodulators that enhance network activity are largely unknown. Here we provide evidence that pituitary adenylate cyclase-activating peptide (PACAP)-specific PAC1 receptors (PAC1Rs) expressed in postnatal day (P)2-P5 mouse OB are functional and enhance network activity as measured by increases in calcium in genetically identified granule cells (GCs). We used confocal Ca(2+) imaging of OB slices from Dlx2-tdTomato mice to visualize GABAergic GCs. To address whether the PACAP-induced Ca(2+) oscillations were direct or indirect effects of PAC1R activation, we used antagonists for the GABA receptors (GABARs) and/or glutamate receptors (GluRs) in the presence and absence of PACAP. Combined block of GABARs and GluRs yielded a 66% decrease in the numbers of PACAP-responsive cells, suggesting that 34% of OB neurons are directly activated by PACAP. Similarly, immunocytochemistry using anti-PAC1 antibody showed that 34% of OB neurons express PAC1R. Blocking either GluRs or GABARs alone indirectly showed that PACAP stimulates release of both glutamate and GABA, which activate GCs. The appearance of PACAP-induced Ca(2+) activity in immature GCs suggests a role for PACAP in GC maturation. To conclude, we find that PACAP has both direct and indirect effects on neonatal OB GABAergic cells and may enhance network activity by promoting glutamate and GABA release. Furthermore, the numbers of PACAP-responsive GCs significantly increased between P2 and P5, suggesting that PACAP-induced Ca(2+) activity contributes to neonatal OB development.
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Affiliation(s)
- Mavis Irwin
- Department of Physiology, University of Utah School of Medicine, Salt Lake City, Utah
| | - Ann Greig
- Department of Physiology, University of Utah School of Medicine, Salt Lake City, Utah
| | - Petr Tvrdik
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, Utah; Interdepartmental Neuroscience Program, University of Utah School of Medicine, Salt Lake City, Utah; and
| | - Mary T Lucero
- Department of Physiology, University of Utah School of Medicine, Salt Lake City, Utah; Interdepartmental Neuroscience Program, University of Utah School of Medicine, Salt Lake City, Utah; and Department of Neuroscience and Physiology, American University of the Caribbean, Cupecoy, Sint Maarten, Netherlands Antilles
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29
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30
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Yu Y, Zhang C. Purinergic signaling negatively regulates activity of an olfactory receptor in an odorant-dependent manner. Neuroscience 2014; 275:89-101. [PMID: 24928349 DOI: 10.1016/j.neuroscience.2014.05.055] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 04/08/2014] [Accepted: 05/28/2014] [Indexed: 01/06/2023]
Abstract
Extracellular purines and pyrimidines are important signaling molecules that mediate diverse biological functions via cell surface purinergic receptors. Although purinergic modulation to olfactory activity has been reported, cell-specific expression and action of purinergic receptors deserve further exploration. We physiologically characterized expression of purinergic receptors in a set of olfactory sensory neurons that are responsive to both acetophenone and benzaldehyde (AB-OSNs). Sparsely distributed in the most ventral olfactory receptor zone, AB-OSNs were activated by P2 purinergic receptor agonists but not by P1 purinergic receptor agonist adenosine. Both P2X-selective agonist α,β-methylene ATP and P2Y-selective agonist uridine 5'-triphosphate (UTP) were stimulatory to AB-OSNs, indicating expression of both P2X and P2Y purinergic receptors in AB-OSNs. Pharmacological characterization of receptor specificity using various P2X and P2Y agonists and antagonists illustrated that P2X1 and P2Y2 receptors played major roles in purinergic signaling in AB-OSNs. Interestingly, the results of purinergic modulation to acetophenone-evoked responses were different from those to benzaldehyde-evoked responses within the same neurons. Activation of P2X1 receptors had more profound inhibitory effects on benzaldehyde-evoked intracellular calcium elevation than on acetophenone-evoked responses within the same neurons, and the reverse was true when P2Y2 receptors were activated. Cross-adaptation data showed that acetophenone and benzaldehyde bound to the same olfactory receptor. Thus, our study has demonstrated that purinergic signaling of P2X and P2Y receptors has different effects on olfactory transduction mediated by a defined olfactory receptor and the consequences of purinergic modulation of olfactory activity might depend on stereotypic structures of the odorant-receptor complex.
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Affiliation(s)
- Y Yu
- Department of Biological and Chemical Sciences, Illinois Institute of Technology, 3101S Dearborn Street, Chicago, IL 60616, USA
| | - C Zhang
- Department of Biological and Chemical Sciences, Illinois Institute of Technology, 3101S Dearborn Street, Chicago, IL 60616, USA.
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Purinergic neuron-glia interactions in sensory systems. Pflugers Arch 2014; 466:1859-72. [DOI: 10.1007/s00424-014-1510-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 03/26/2014] [Accepted: 03/26/2014] [Indexed: 02/06/2023]
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Verkhratsky A, Burnstock G. Purinergic and glutamatergic receptors on astroglia. ADVANCES IN NEUROBIOLOGY 2014; 11:55-79. [PMID: 25236724 DOI: 10.1007/978-3-319-08894-5_4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Astroglial cells express many neurotransmitter receptors; the receptors to glutamate and ATP being the most abundant. Here, we provide a concise overview on the expression and main properties of astroglial glutamate receptors (ionotropic receptors represented by AMPA and NMDA subtypes) and metabotropic (mainly mGluR5 and mGluR3 subtypes) and purinoceptors (adenosine receptors of A1, A2A, A2B, and A3 types, ionotropic P2X1/5 and P2X7 subtypes, and metabotropic P2Y purinoceptors). We also discuss the role of these receptors in glial physiology and pathophysiology.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Life Sciences, School of Biological Sciences, The University of Manchester, 1.124 Stopford Building, Oxford Road, Manchester, M13 9PT, UK,
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Evidence for A1 and A 3 receptors mediating adenosine-induced intracellular calcium release in the dorsal root ganglion neurons by using confocal microscopy imaging. Lasers Med Sci 2013; 29:1209-15. [PMID: 24352876 DOI: 10.1007/s10103-013-1511-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Accepted: 12/05/2013] [Indexed: 10/25/2022]
Abstract
Adenosine exerts a key role in analgesia. In the present study, adenosine-induced Ca(2+) responses were revealed by using confocal microscopy imaging in the rat dorsal root ganglia (DRG) neurons in vitro. Our results showed that adenosine could evoke increases in the intracellular Ca(2+) concentration in the DRG neurons. In addition, by application of selective receptor antagonists, two types of receptors, A1R and A3R, were identified to be involved in the adenosine-induced Ca(2+) release from intracellular stores in neurons. Altogether, these results suggest that confocal microscopy imaging combined with fluorescent dyes could help to detect the analgesic-induced ion signaling in single cell.
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Rapid stimulus-evoked astrocyte Ca2+ elevations and hemodynamic responses in mouse somatosensory cortex in vivo. Proc Natl Acad Sci U S A 2013; 110:E4678-87. [PMID: 24218625 DOI: 10.1073/pnas.1310065110] [Citation(s) in RCA: 142] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Increased neuron and astrocyte activity triggers increased brain blood flow, but controversy exists over whether stimulation-induced changes in astrocyte activity are rapid and widespread enough to contribute to brain blood flow control. Here, we provide evidence for stimulus-evoked Ca(2+) elevations with rapid onset and short duration in a large proportion of cortical astrocytes in the adult mouse somatosensory cortex. Our improved detection of the fast Ca(2+) signals is due to a signal-enhancing analysis of the Ca(2+) activity. The rapid stimulation-evoked Ca(2+) increases identified in astrocyte somas, processes, and end-feet preceded local vasodilatation. Fast Ca(2+) responses in both neurons and astrocytes correlated with synaptic activity, but only the astrocytic responses correlated with the hemodynamic shifts. These data establish that a large proportion of cortical astrocytes have brief Ca(2+) responses with a rapid onset in vivo, fast enough to initiate hemodynamic responses or influence synaptic activity.
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Domijan AM, Kovac S, Abramov AY. Lipid peroxidation is essential for phospholipase C activity and the inositol-trisphosphate-related Ca²⁺ signal. J Cell Sci 2013; 127:21-6. [PMID: 24198393 DOI: 10.1242/jcs.138370] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Reactive oxygen species (ROS) are produced in enzymatic and non-enzymatic reactions and have important roles in cell signalling but also detrimental effects. ROS-induced damage has been implicated in a number of neurological diseases; however, antioxidant therapies targeting brain diseases have been unsuccessful. Such failure might be related to inhibition of ROS-induced signalling in the brain. Using direct kinetic measures of lipid peroxidation in astrocytes and measurements of lipid peroxidation products in brain tissue, we here show that phospholipase C (PLC) preferentially cleaves oxidised lipids. Because of this, an increase in the rate of lipid peroxidation leads to increased Ca(2+) release from endoplasmic reticulum (ER) stores in response to physiological activation of purinoreceptors with ATP. Both vitamin E and its water-soluble analogue Trolox, potent ROS scavengers, were able to suppress PLC activity, therefore dampening intracellular Ca(2+) signalling. This implies that antioxidants can compromise intracellular Ca(2+) signalling through inhibition of PLC, and that PLC plays a dual role - signalling and antioxidant defence.
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Thyssen A, Stavermann M, Buddrus K, Doengi M, Ekberg JA, St John JA, Deitmer JW, Lohr C. Spatial and developmental heterogeneity of calcium signaling in olfactory ensheathing cells. Glia 2012; 61:327-37. [PMID: 23109369 DOI: 10.1002/glia.22434] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Accepted: 09/11/2012] [Indexed: 12/24/2022]
Abstract
Olfactory ensheathing cells (OECs) are specialized glial cells in the mammalian olfactory system supporting growth of axons from the olfactory epithelium into the olfactory bulb. OECs in the olfactory bulb can be subdivided into OECs of the outer nerve layer and the inner nerve layer according to the expression of marker proteins and their location in the nerve layer. In the present study, we have used confocal calcium imaging of OECs in acute mouse brain slices and olfactory bulbs in toto to investigate physiological differences between OEC subpopulations. OECs in the outer nerve layer, but not the inner nerve layer, responded to glutamate, ATP, serotonin, dopamine, carbachol, and phenylephrine with increases in the cytosolic calcium concentration. The calcium responses consisted of a transient and a tonic component, the latter being mediated by store-operated calcium entry. Calcium measurements in OECs during the first three postnatal weeks revealed a downregulation of mGluR(1) and P2Y(1) receptor-mediated calcium signaling within the first 2 weeks, suggesting that the expression of these receptors is developmentally controlled. In addition, electrical stimulation of sensory axons evoked calcium signaling via mGluR(1) and P2Y(1) only in outer nerve layer OECs. Downregulation of the receptor-mediated calcium responses in postnatal animals is reflected by a decrease in amplitude of stimulation-evoked calcium transients in OECs from postnatal days 3 to 21. In summary, the results presented reveal striking differences in receptor responses during development and in axon-OEC communication between the two subpopulations of OECs in the olfactory bulb.
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Affiliation(s)
- Anne Thyssen
- Abteilung für Allgemeine Zoologie, TU Kaiserslautern, Germany
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Stavermann M, Buddrus K, St John JA, Ekberg JA, Nilius B, Deitmer JW, Lohr C. Temperature-dependent calcium-induced calcium release via InsP3 receptors in mouse olfactory ensheathing glial cells. Cell Calcium 2012; 52:113-23. [DOI: 10.1016/j.ceca.2012.04.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2011] [Revised: 03/22/2012] [Accepted: 04/24/2012] [Indexed: 02/07/2023]
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Fischer T, Rotermund N, Lohr C, Hirnet D. P2Y1 receptor activation by photolysis of caged ATP enhances neuronal network activity in the developing olfactory bulb. Purinergic Signal 2011; 8:191-8. [PMID: 22187118 DOI: 10.1007/s11302-011-9286-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Accepted: 11/29/2011] [Indexed: 01/03/2023] Open
Abstract
It has recently been shown that adenosine-5'-triphosphate (ATP) is released together with glutamate from sensory axons in the olfactory bulb, where it stimulates calcium signaling in glial cells, while responses in identified neurons to ATP have not been recorded in the olfactory bulb yet. We used photolysis of caged ATP to elicit a rapid rise in ATP and measured whole-cell current responses in mitral cells, the output neurons of the olfactory bulb, in acute mouse brain slices. Wide-field photolysis of caged ATP evoked an increase in synaptic inputs in mitral cells, indicating an ATP-dependent increase in network activity. The increase in synaptic activity was accompanied by calcium transients in the dendritic tuft of the mitral cell, as measured by confocal calcium imaging. The stimulating effect of ATP on the network activity could be mimicked by photo release of caged adenosine 5'-diphosphate, and was inhibited by the P2Y(1) receptor antagonist MRS 2179. Local photolysis of caged ATP in the glomerulus innervated by the dendritic tuft of the recorded mitral cell elicited currents similar to those evoked by wide-field illumination. The results indicate that activation of P2Y(1) receptors in the glomerulus can stimulate network activity in the olfactory bulb.
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Affiliation(s)
- Timo Fischer
- Division of Neurophysiology, Biocenter Grindel, University of Hamburg, Hamburg, Germany
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Molnár T, Dobolyi A, Nyitrai G, Barabás P, Héja L, Emri Z, Palkovits M, Kardos J. Calcium signals in the nucleus accumbens: activation of astrocytes by ATP and succinate. BMC Neurosci 2011; 12:96. [PMID: 21967230 PMCID: PMC3199278 DOI: 10.1186/1471-2202-12-96] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Accepted: 10/03/2011] [Indexed: 12/13/2022] Open
Abstract
Background Accumulating evidence suggests that glial signalling is activated by different brain functions. However, knowledge regarding molecular mechanisms of activation or their relation to neuronal activity is limited. The purpose of the present study is to identify the characteristics of ATP-evoked glial signalling in the brain reward area, the nucleus accumbens (NAc), and thereby to explore the action of citric acid cycle intermediate succinate (SUC). Results We described the burst-like propagation of Ca2+ transients evoked by ATP in acute NAc slices from rat brain. Co-localization of the ATP-evoked Ca2+ signalling with immunoreactivities of the astroglia-specific gap junction forming channel protein connexin43 (Cx43) and the glial fibrillary acidic protein (GFAP) indicated that the responsive cells were a subpopulation of Cx43 and GFAP immunoreactive astrocytes. The ATP-evoked Ca2+ transients were present under the blockade of neuronal activity, but were inhibited by Ca2+ store depletion and antagonism of the G protein coupled purinergic P2Y1 receptor subtype-specific antagonist MRS2179. Similarly, Ca2+ transients evoked by the P2Y1 receptor subtype-specific agonist 2-(Methylthio)adenosine 5'-diphosphate were also blocked by MRS2179. These characteristics implied that intercellular Ca2+ signalling originated from the release of Ca2+ from internal stores, triggered by the activation of P2Y1 receptors. Inhibition by the gap junction blockers carbenoxolone and flufenamic acid and by an antibody raised against the gating-associated segment of Cx43 suggested that intercellular Ca2+ signalling proceeded through gap junctions. We demonstrated for the first time that extracellular SUC also evoked Ca2+ transients (EC50 = 50-60 μM) in about 15% of the ATP-responsive NAc astrocytes. By contrast to glial cells, electrophysiologically identified NAc neurons surrounded by ATP-responsive astrocytes were not activated simultaneously. Conclusions We concluded, therefore, that ATP- and SUC-sensitive Ca2+ transients appear to represent a signalling layer independent of NAc neurons. This previously unrecognised glial action of SUC, a major cellular energy metabolite, may play a role in linking metabolism to Ca2+ signalling in astrocytic networks under physiological and pathological conditions such as exercise and metabolic diseases.
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Affiliation(s)
- Tünde Molnár
- Department of Neurochemistry, Institute of Biomolecular Chemistry, Chemical Research Center, Hungarian Academy of Sciences, Pusztaszeriút 59-67, 1025 Budapest, Hungary
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Development of a glial network in the olfactory nerve: role of calcium and neuronal activity. ACTA ACUST UNITED AC 2011; 6:245-61. [PMID: 21933469 DOI: 10.1017/s1740925x11000081] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
In adult olfactory nerves of mammals and moths, a network of glial cells ensheathes small bundles of olfactory receptor axons. In the developing antennal nerve (AN) of the moth Manduca sexta, the axons of olfactory receptor neurons (ORNs) migrate from the olfactory sensory epithelium toward the antennal lobe. Here we explore developmental interactions between ORN axons and AN glial cells. During early stages in AN glial-cell migration, glial cells are highly dye coupled, dividing glia are readily found in the nerve and AN glial cells label strongly for glutamine synthetase. By the end of this period, dye-coupling is rare, glial proliferation has ceased, glutamine synthetase labeling is absent, and glial processes have begun to extend to enwrap bundles of axons, a process that continues throughout the remainder of metamorphic development. Whole-cell and perforated-patch recordings in vivo from AN glia at different stages of network formation revealed two potassium currents and an R-like calcium current. Chronic in vivo exposure to the R-type channel blocker SNX-482 halted or greatly reduced AN glial migration. Chronically blocking spontaneous Na-dependent activity by injection of tetrodotoxin reduced the glial calcium current implicating an activity-dependent interaction between ORNs and glial cells in the development of glial calcium currents.
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Armentero MT, Pinna A, Ferré S, Lanciego JL, Müller CE, Franco R. Past, present and future of A(2A) adenosine receptor antagonists in the therapy of Parkinson's disease. Pharmacol Ther 2011; 132:280-99. [PMID: 21810444 DOI: 10.1016/j.pharmthera.2011.07.004] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Accepted: 07/07/2011] [Indexed: 12/20/2022]
Abstract
Several selective antagonists for adenosine A(2A) receptors (A(2A)R) are currently under evaluation in clinical trials (phases I to III) to treat Parkinson's disease, and they will probably soon reach the market. The usefulness of these antagonists has been deduced from studies demonstrating functional interactions between dopamine D₂ and adenosine A(2A) receptors in the basal ganglia. At present it is believed that A(2A)R antagonists can be used in combination with the dopamine precursor L-DOPA to minimize the motor symptoms of Parkinson's patients. However, a considerable body of data indicates that in addition to ameliorating motor symptoms, adenosine A(2A)R antagonists may also prevent neurodegeneration. Despite these promising indications, one further issue must be considered in order to develop fully optimized antiparkinsonian drug therapy, namely the existence of (hetero)dimers/oligomers of G protein-coupled receptors, a topic that is currently the focus of intense debate within the scientific community. Dopamine D₂ receptors (D₂Rs) expressed in the striatum are known to form heteromers with A(2A) adenosine receptors. Thus, the development of heteromer-specific A(2A) receptor antagonists represents a promising strategy for the identification of more selective and safer drugs.
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Affiliation(s)
- Marie Therese Armentero
- Laboratory of Functional Neurochemistry, Interdepartmental Research Centre for Parkinson's Disease, IRCCS National Institute of Neurology "C. Mondino", Pavia, Italy
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Lohr C, Thyssen A, Hirnet D. Extrasynaptic neuron-glia communication: The how and why. Commun Integr Biol 2011; 4:109-11. [PMID: 21509197 DOI: 10.4161/cib.4.1.14184] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Accepted: 11/11/2010] [Indexed: 01/05/2023] Open
Abstract
Chemical synaptic transmission between neurons is believed to take place at specialized sites of cell contact, comprising presynaptic terminals and postsynaptic membranes. Neurotransmitter release has been shown to occur also extrasynaptically, mainly targeting glial cells. In a recent study, we investigated the mechanism of extrasynaptic glutamate and ATP release along sensory axons in the olfactory nerve layer. Transmitter release was mediated by calcium-dependent vesicle fusion and triggered calcium transients in adjacent glial cells. These calcium transients were coupled to vasoresponses, indicating that glial calcium signaling mediates neurovascular coupling not only in synaptic brain regions such as gray matter, but also in brain regions devoid of synapses.
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Affiliation(s)
- Christian Lohr
- Division of Animal Physiology; University of Hamburg; Hamburg
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Hassenklöver T, Schulz P, Peters A, Schwartz P, Schild D, Manzini I. Purinergic receptor-mediated Ca signaling in the olfactory bulb and the neurogenic area of the lateral ventricles. Purinergic Signal 2010; 6:429-45. [PMID: 21437013 PMCID: PMC3033506 DOI: 10.1007/s11302-010-9207-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Accepted: 11/18/2010] [Indexed: 02/07/2023] Open
Abstract
Like in other vertebrates, the anterior part of the telencephalon of amphibians mainly consists of the olfactory bulb (OB), but different from higher vertebrates, the lateral telencephalic ventricles of larval Xenopus laevis expand deep into the anterior telencephalon. The neurogenic periventricular zone (PVZ) of the lateral ventricles generates new OB neurons throughout the animal's lifetime. We investigated the ultrastructural organization of the PVZ and found that within a time period of 24 h, 42.54 ± 6.65% of all PVZ cells were actively proliferating. Functional purinergic receptors are widespread in the central nervous system and their activation has been associated with many critical physiological processes, including the regulation of cell proliferation. In the present study we identified and characterized the purinergic system of the OB and the PVZ. ATP and 2MeSATP induced strong [Ca(2+)](i) increases in cells of both regions, which could be attenuated by purinergic antagonists. However, a more thorough pharmacological investigation revealed clear differences between the two brain regions. Cells of the OB almost exclusively express ionotropic P2X purinergic receptor subtypes, whereas PVZ cells express both ionotropic P2X and metabotropic P1 and P2Y receptor subtypes. The P2X receptors expressed in the OB are evidently not involved in the immediate processing of olfactory information.
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Ectopic vesicular neurotransmitter release along sensory axons mediates neurovascular coupling via glial calcium signaling. Proc Natl Acad Sci U S A 2010; 107:15258-63. [PMID: 20696909 DOI: 10.1073/pnas.1003501107] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Neurotransmitter release generally is considered to occur at active zones of synapses, and ectopic release of neurotransmitters has been demonstrated in a few instances. However, the mechanism of ectopic neurotransmitter release is poorly understood. We took advantage of the intimate morphological and functional proximity of olfactory receptor axons and specialized glial cells, olfactory ensheathing cells (OECs), to study ectopic neurotransmitter release. Axonal stimulation evoked purinergic and glutamatergic Ca(2+) responses in OECs, indicating ATP and glutamate release. In axons expressing synapto-pHluorin, stimulation evoked an increase in synapto-pHluorin fluorescence, indicative of vesicle fusion. Transmitter release was dependent on Ca(2+) and could be inhibited by bafilomycin A1 and botulinum toxin A. Ca(2+) transients in OECs evoked by ATP, axonal stimulation, and laser photolysis of NP-EGTA resulted in constriction of adjacent blood vessels. Our results indicate that ATP and glutamate are released ectopically by vesicles along axons and mediate neurovascular coupling via glial Ca(2+) signaling.
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Novel adenosine and cAMP signalling pathways in migrating glial cells. Cell Calcium 2010; 48:83-90. [PMID: 20688392 DOI: 10.1016/j.ceca.2010.07.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Revised: 07/08/2010] [Accepted: 07/09/2010] [Indexed: 11/22/2022]
Abstract
This study was aimed at characterizing the effect of purinergic transmission on migration of embryonic ciliary ganglion satellite glial cells. Application of adenosine significantly decreased the rate of migration of glial cells whereas no differences were observed in the presence of ATP. The A(2B) receptor antagonist reverted this action, but application of an A(2A) receptor antagonist or a cAMP-protein kinase inhibitor had no effect on the agonist's stimulation. Forskolin, which stimulates adenylate cyclase activity, and the cAMP analogue 8-CPT-2'-O-Me-cAMP, which selectively activates the guanine exchange factor Epac1, mimicked the effect of adenosine. In addition, intracellular calcium measurements studies revealed that application of either adenosine or ATP induced an increase in [Ca(2+)]i and that the adenosine-induced [Ca(2+)]i response was due to Ca(2+) entry and was blocked by an A(2A) receptor antagonist, SCH 58261, or by high Gd(3+) concentrations. Furthermore, forskolin, but not 8-CPT-2'-O-Me-cAMP, activated the Ca(2+) entry which was blocked by Gd(3+) and was independent of cAMP-protein kinase activity. These results demonstrate the involvement of purinergic P1 signalling in the regulation of cellular migration, and point to the importance of adenosine as a negative modulator of migration of peripheral developing glial cells and as an activator of Ca(2+) entry.
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Ion changes and signalling in perisynaptic glia. ACTA ACUST UNITED AC 2010; 63:113-29. [DOI: 10.1016/j.brainresrev.2009.10.006] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Revised: 09/23/2009] [Accepted: 10/01/2009] [Indexed: 01/30/2023]
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GABA uptake-dependent Ca(2+) signaling in developing olfactory bulb astrocytes. Proc Natl Acad Sci U S A 2009; 106:17570-5. [PMID: 19805126 DOI: 10.1073/pnas.0809513106] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
We studied GABAergic signaling in astrocytes of olfactory bulb slices using confocal Ca(2+) imaging and two-photon Na(+) imaging. GABA evoked Ca(2+) transients in astrocytes that persisted in the presence of GABA(A) and GABA(B) receptor antagonists, but were suppressed by inhibition of GABA uptake by SNAP 5114. Withdrawal of external Ca(2+) blocked GABA-induced Ca(2+) transients, and depletion of Ca(2+) stores with cyclopiazonic acid reduced Ca(2+) transients by approximately 90%. This indicates that the Ca(2+) transients depend on external Ca(2+), but are mainly mediated by intracellular Ca(2+) release, conforming with Ca(2+)-induced Ca(2+) release. Inhibition of ryanodine receptors did not affect GABA-induced Ca(2+) transients, whereas the InsP(3) receptor blocker 2-APB inhibited the Ca(2+) transients. GABA also induced Na(+) increases in astrocytes, potentially reducing Na(+)/Ca(2+) exchange. To test whether reduction of Na(+)/Ca(2+) exchange induces Ca(2+) signaling, we inhibited Na(+)/Ca(2+) exchange with KB-R7943, which mimicked GABA-induced Ca(2+) transients. Endogenous GABA release from neurons, activated by stimulation of afferent axons or NMDA application, also triggered Ca(2+) transients in astrocytes. The significance of GABAergic Ca(2+) signaling in astrocytes for control of blood flow is demonstrated by SNAP 5114-sensitive constriction of blood vessels accompanying GABA uptake. The results suggest that GABAergic signaling is composed of GABA uptake-mediated Na(+) rises that reduce Na(+)/Ca(2+) exchange, thereby leading to a Ca(2+) increase sufficient to trigger Ca(2+)-induced Ca(2+) release via InsP(3) receptors. Hence, GABA transporters not only remove GABA from the extracellular space, but may also contribute to intracellular signaling and astrocyte function, such as control of blood flow.
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Gulbransen BD, Sharkey KA. Purinergic neuron-to-glia signaling in the enteric nervous system. Gastroenterology 2009; 136:1349-58. [PMID: 19250649 DOI: 10.1053/j.gastro.2008.12.058] [Citation(s) in RCA: 140] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2008] [Revised: 12/03/2008] [Accepted: 12/29/2008] [Indexed: 01/28/2023]
Abstract
BACKGROUND & AIMS Enteric glia are intimately associated with neurons in the enteric nervous system (ENS) and display morphologic and molecular similarities to central nervous system (CNS) astrocytes. Enteric glia express neurotransmitter receptors, suggesting that, like astrocytes, they are active participants in neuronal communication. In the ENS, the purine adenosine triphosphate (ATP) is co-released with the neurotransmitters noradrenaline and acetylcholine. Enteric glia express purinergic receptors and respond to ATP in vitro, suggesting that enteric glia participate in functional gastrointestinal responses to nerve signaling. We investigated whether enteric glia are activated by ATP released from enteric neurons. METHODS Synaptic activity was elicited in enteric neurons by electrically stimulating interganglionic connectives in the myenteric plexus of the guinea pig colon. Activity in enteric glial cells was detected by imaging intracellular calcium in situ. RESULTS Neuronal stimulation elicited increases in intracellular calcium in enteric glial cells that were blocked by tetrodotoxin, the nonselective purinergic receptor antagonist pyridoxal phosphate-6-azo(benzene-2,4-disulfonic acid) tetrasodium salt hydrate (PPADS), and the phospholipase C inhibitor U73122. Furthermore, enteric glia responded robustly to exogenously applied ATP in situ, and the ATP response was blocked by PPADS and U73122. Data from pharmacologic profiling and immunohistochemical analyses support the hypothesis that P2Y4 is the major functional receptor underlying the ATP response in enteric glia. CONCLUSIONS Our results provide direct evidence for functional purinergic neuron-glia communication in the enteric nervous system, raising the possibility that ATP released with neurotransmitters during enteric synaptic transmission functions to signal to enteric glia.
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Affiliation(s)
- Brian D Gulbransen
- Hotchkiss Brain Institute, Department of Physiology and Biophysics, University of Calgary, Calgary, Alberta, Canada.
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Rosa AO, Rapoport SI. Intracellular- and extracellular-derived Ca(2+) influence phospholipase A(2)-mediated fatty acid release from brain phospholipids. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:697-705. [PMID: 19327408 DOI: 10.1016/j.bbalip.2009.03.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Revised: 03/01/2009] [Accepted: 03/11/2009] [Indexed: 02/01/2023]
Abstract
Docosahexaenoic acid (DHA) and arachidonic acid (AA) are found in high concentrations in brain cell membranes and are important for brain function and structure. Studies suggest that AA and DHA are hydrolyzed selectively from the sn-2 position of synaptic membrane phospholipids by Ca(2+)-dependent cytosolic phospholipase A(2) (cPLA(2)) and Ca(2+)-independent phospholipase A(2) (iPLA(2)), respectively, resulting in increased levels of the unesterified fatty acids and lysophospholipids. Cell studies also suggest that AA and DHA release depend on increased concentrations of Ca(2+), even though iPLA(2) has been thought to be Ca(2+)-independent. The source of Ca(2+) for activation of cPLA(2) is largely extracellular, whereas Ca(2+) released from the endoplasmic reticulum can activate iPLA(2) by a number of mechanisms. This review focuses on the role of Ca(2+) in modulating cPLA(2) and iPLA(2) activities in different conditions. Furthermore, a model is suggested in which neurotransmitters regulate the activity of these enzymes and thus the balanced and localized release of AA and DHA from phospholipid in the brain, depending on the primary source of the Ca(2+) signal.
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Affiliation(s)
- Angelo O Rosa
- Brain Physiology and Metabolism Section, National Institute on Aging, National Institutes of Health, Bethesda, MD 20892, USA.
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