1
|
Berndt A, Lee J, Nguyen A, Jin Z, Moghadasi A, Gibbs C, Wait S, Evitts K, Asencio A, Bremner S, Zuniga S, Chavan V, Williams A, Smith A, Moussavi-Harami F, Regnier M, Young J, Mack D, Nance E, Boyle P. Far-red and sensitive sensor for monitoring real time H2O2 dynamics with subcellular resolution and in multi-parametric imaging applications. RESEARCH SQUARE 2024:rs.3.rs-3974015. [PMID: 38699332 PMCID: PMC11065073 DOI: 10.21203/rs.3.rs-3974015/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2024]
Abstract
H 2 O 2 is a key oxidant in mammalian biology and a pleiotropic signaling molecule at the physiological level, and its excessive accumulation in conjunction with decreased cellular reduction capacity is often found to be a common pathological marker. Here, we present a red fluorescent Genetically Encoded H 2 O 2 Indicator (GEHI) allowing versatile optogenetic dissection of redox biology. Our new GEHI, oROS-HT, is a chemigenetic sensor utilizing a HaloTag and Janelia Fluor (JF) rhodamine dye as fluorescent reporters. We developed oROS-HT through a structure-guided approach aided by classic protein structures and recent protein structure prediction tools. Optimized with JF 635 , oROS-HT is a sensor with 635 nm excitation and 650 nm emission peaks, allowing it to retain its brightness while monitoring intracellular H 2 O 2 dynamics. Furthermore, it enables multi-color imaging in combination with blue-green fluorescent sensors for orthogonal analytes and low auto-fluorescence interference in biological tissues. Other advantages of oROS-HT over alternative GEHIs are its fast kinetics, oxygen-independent maturation, low pH sensitivity, lack of photo-artifact, and lack of intracellular aggregation. Here, we demonstrated efficient subcellular targeting and how oROS-HT can map inter and intracellular H 2 O 2 diffusion at subcellular resolution. Lastly, we used oROS-HT with other green fluorescence reporters to investigate the transient effect of the anti-inflammatory agent auranofin on cellular redox physiology and calcium levels via multi-parametric, dual-color imaging.
Collapse
|
2
|
Wait SJ, Expòsit M, Lin S, Rappleye M, Lee JD, Colby SA, Torp L, Asencio A, Smith A, Regnier M, Moussavi-Harami F, Baker D, Kim CK, Berndt A. Machine learning-guided engineering of genetically encoded fluorescent calcium indicators. NATURE COMPUTATIONAL SCIENCE 2024; 4:224-236. [PMID: 38532137 DOI: 10.1038/s43588-024-00611-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 02/15/2024] [Indexed: 03/28/2024]
Abstract
Here we used machine learning to engineer genetically encoded fluorescent indicators, protein-based sensors critical for real-time monitoring of biological activity. We used machine learning to predict the outcomes of sensor mutagenesis by analyzing established libraries that link sensor sequences to functions. Using the GCaMP calcium indicator as a scaffold, we developed an ensemble of three regression models trained on experimentally derived GCaMP mutation libraries. The trained ensemble performed an in silico functional screen on 1,423 novel, uncharacterized GCaMP variants. As a result, we identified the ensemble-derived GCaMP (eGCaMP) variants, eGCaMP and eGCaMP+, which achieve both faster kinetics and larger ∆F/F0 responses upon stimulation than previously published fast variants. Furthermore, we identified a combinatorial mutation with extraordinary dynamic range, eGCaMP2+, which outperforms the tested sixth-, seventh- and eighth-generation GCaMPs. These findings demonstrate the value of machine learning as a tool to facilitate the efficient engineering of proteins for desired biophysical characteristics.
Collapse
Affiliation(s)
- Sarah J Wait
- Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA, USA
- Institute of Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Marc Expòsit
- Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA, USA
- Institute for Protein Design, University of Washington, Seattle, WA, USA
| | - Sophia Lin
- Center for Neuroscience, University of California, Davis, Davis, CA, USA
- Department of Neurology, University of California, Davis, Davis, CA, USA
| | - Michael Rappleye
- Institute of Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Institute of Pharmacology and Toxicology, University of Zürich, Zurich, Switzerland
| | - Justin Daho Lee
- Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA, USA
- Institute of Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Samuel A Colby
- Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA, USA
| | - Lily Torp
- Institute of Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Anthony Asencio
- Institute of Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Annette Smith
- Institute of Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Michael Regnier
- Institute of Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Farid Moussavi-Harami
- Institute of Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA
- Division of Cardiology, University of Washington, Seattle, WA, USA
| | - David Baker
- Institute for Protein Design, University of Washington, Seattle, WA, USA
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA
| | - Christina K Kim
- Center for Neuroscience, University of California, Davis, Davis, CA, USA
- Department of Neurology, University of California, Davis, Davis, CA, USA
| | - Andre Berndt
- Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA, USA.
- Institute of Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA.
- Department of Bioengineering, University of Washington, Seattle, WA, USA.
- Center for Neurobiology of Addiction, Pain, and Emotion, University of Washington, Seattle, WA, USA.
| |
Collapse
|
3
|
Lee JD, Nguyen A, Jin ZR, Moghadasi A, Gibbs CE, Wait SJ, Evitts KM, Asencio A, Bremner SB, Zuniga S, Chavan V, Williams A, Smith N, Regnier M, Young JE, Mack D, Nance E, Boyle PM, Berndt A. Far-red and sensitive sensor for monitoring real time H 2O 2 dynamics with subcellular resolution and in multi-parametric imaging applications. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.06.579232. [PMID: 38370715 PMCID: PMC10871219 DOI: 10.1101/2024.02.06.579232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
H2O2 is a key oxidant in mammalian biology and a pleiotropic signaling molecule at the physiological level, and its excessive accumulation in conjunction with decreased cellular reduction capacity is often found to be a common pathological marker. Here, we present a red fluorescent Genetically Encoded H2O2 Indicator (GEHI) allowing versatile optogenetic dissection of redox biology. Our new GEHI, oROS-HT, is a chemigenetic sensor utilizing a HaloTag and Janelia Fluor (JF) rhodamine dye as fluorescent reporters. We developed oROS-HT through a structure-guided approach aided by classic protein structures and recent protein structure prediction tools. Optimized with JF635, oROS-HT is a sensor with 635 nm excitation and 650 nm emission peaks, allowing it to retain its brightness while monitoring intracellular H2O2 dynamics. Furthermore, it enables multi-color imaging in combination with blue-green fluorescent sensors for orthogonal analytes and low auto-fluorescence interference in biological tissues. Other advantages of oROS-HT over alternative GEHIs are its fast kinetics, oxygen-independent maturation, low pH sensitivity, lack of photo-artifact, and lack of intracellular aggregation. Here, we demonstrated efficient subcellular targeting and how oROS-HT can map inter and intracellular H2O2 diffusion at subcellular resolution. Lastly, we used oROS-HT with the green fluorescent calcium indicator Fluo-4 to investigate the transient effect of the anti-inflammatory agent auranofin on cellular redox physiology and calcium levels via multi-parametric, dual-color imaging.
Collapse
Affiliation(s)
- Justin Daho Lee
- Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA, USA
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Amanda Nguyen
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Zheyu Ruby Jin
- Department of Chemical Engineering, University of Washington, Seattle WA, USA
| | - Aida Moghadasi
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Chelsea E. Gibbs
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Sarah J. Wait
- Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA, USA
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Kira M. Evitts
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Anthony Asencio
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
- Center for Cardiovascular Biology, University of Washington, Seattle WA, USA
| | - Samantha B Bremner
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Shani Zuniga
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Vedant Chavan
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Andy Williams
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Netta Smith
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Michael Regnier
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
- Center for Cardiovascular Biology, University of Washington, Seattle WA, USA
| | - Jessica E. Young
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA
| | - David Mack
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
- Department of Rehabilitation Medicine, University of Washington, Seattle, WA, USA
| | - Elizabeth Nance
- Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA, USA
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Department of Chemical Engineering, University of Washington, Seattle WA, USA
| | - Patrick M. Boyle
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
- Center for Cardiovascular Biology, University of Washington, Seattle WA, USA
| | - Andre Berndt
- Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA, USA
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| |
Collapse
|
4
|
Pereira MF, Amaral IM, Lopes C, Leitão C, Madeira D, Lopes JP, Gonçalves FQ, Canas PM, Cunha RA, Agostinho P. l-α-aminoadipate causes astrocyte pathology with negative impact on mouse hippocampal synaptic plasticity and memory. FASEB J 2021; 35:e21726. [PMID: 34196433 DOI: 10.1096/fj.202100336r] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 05/12/2021] [Accepted: 05/24/2021] [Indexed: 12/26/2022]
Abstract
Increasing evidence shows that astrocytes, by releasing and uptaking neuroactive molecules, regulate synaptic plasticity, considered the neurophysiological basis of memory. This study investigated the impact of l-α-aminoadipate (l-AA) on astrocytes which sense and respond to stimuli at the synaptic level and modulate hippocampal long-term potentiation (LTP) and memory. l-AA selectivity toward astrocytes was proposed in the early 70's and further tested in different systems. Although it has been used for impairing the astrocytic function, its effects appear to be variable in different brain regions. To test the effects of l-AA in the hippocampus of male C57Bl/6 mice we performed two different treatments (ex vivo and in vivo) and took advantage of other compounds that were reported to affect astrocytes. l-AA superfusion did not affect the basal synaptic transmission but decreased LTP magnitude. Likewise, trifluoroacetate and dihydrokainate decreased LTP magnitude and occluded the effect of l-AA on synaptic plasticity, confirming l-AA selectivity. l-AA superfusion altered astrocyte morphology, increasing the length and complexity of their processes. In vivo, l-AA intracerebroventricular injection not only reduced the astrocytic markers but also LTP magnitude and impaired hippocampal-dependent memory in mice. Interestingly, d-serine administration recovered hippocampal LTP reduction triggered by l-AA (2 h exposure in hippocampal slices), whereas in mice injected with l-AA, the superfusion of d-serine did not fully rescue LTP magnitude. Overall, these data show that both l-AA treatments affect astrocytes differently, astrocytic activation or loss, with similar negative outcomes on hippocampal LTP, implying that opposite astrocytic adaptive alterations are equally detrimental for synaptic plasticity.
Collapse
Affiliation(s)
| | - Inês M Amaral
- Center for Neuroscience and Cell Biology, CNC, Coimbra, Portugal
| | - Cátia Lopes
- Center for Neuroscience and Cell Biology, CNC, Coimbra, Portugal
| | - Catarina Leitão
- Center for Neuroscience and Cell Biology, CNC, Coimbra, Portugal
| | - Daniela Madeira
- Center for Neuroscience and Cell Biology, CNC, Coimbra, Portugal.,Faculty of Medicine, University of Coimbra, FMUC, Coimbra, Portugal
| | - João P Lopes
- Center for Neuroscience and Cell Biology, CNC, Coimbra, Portugal
| | | | - Paula M Canas
- Center for Neuroscience and Cell Biology, CNC, Coimbra, Portugal
| | - Rodrigo A Cunha
- Center for Neuroscience and Cell Biology, CNC, Coimbra, Portugal.,Faculty of Medicine, University of Coimbra, FMUC, Coimbra, Portugal
| | - Paula Agostinho
- Center for Neuroscience and Cell Biology, CNC, Coimbra, Portugal.,Faculty of Medicine, University of Coimbra, FMUC, Coimbra, Portugal
| |
Collapse
|
5
|
Kishima K, Tachibana T, Yamanaka H, Kobayashi K, Okubo M, Maruo K, Noguchi K. Role of Rho-associated coiled-coil containing protein kinase in the spinal cord injury induced neuropathic pain. Spine J 2021; 21:343-351. [PMID: 32853793 DOI: 10.1016/j.spinee.2020.08.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 08/20/2020] [Accepted: 08/23/2020] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Spinal cord injury (SCI) can lead to increased phosphorylation of p38 in spinal cord microglia. This is one of the main causes for the development of persistent pain. Recently, we reported our study on the activation of p38 mitogen-activated protein kinases (MAPK) in spinal microglia, which has been considered the key molecule for the onset and maintenance of neuropathic pain after peripheral nerve injury, using a rat model. We also reported that the RhoA/Rho-associated coiled-coil containing protein kinase (ROCK) pathway mediates p38 activation in spinal microglia in peripheral nerve injury. But the precise mechanisms of neuropathic pain induced by SCI are still unclear. PURPOSE This study aimed to examine the activation of microglia and the p38 MAPK expression in the lumbar spinal cord after thoracic SCI in rats, and the correlation to the therapeutic effect of ROCK inhibitor ripasudil in rats with SCI. STUDY DESIGN Male Sprague-Dawley rats underwent thoracic (T10) spinal cord contusion injury using an Infinite Horizon impactor device. SCI rats received ROCK inhibitor ripasudil (24 nmol/day or 240 nmol/day) from just before SCI to 3 days after SCI. METHODS The mechanical threshold in the rat's hind paws was measured over four weeks. Morphology of microglia and phosphorylation of p38 (p-p38) in the lumbar spinal cord and were analyzed using immunohistochemistry. RESULTS The p-p38 positive cell and Iba1 (a maker of microglia) positive area were significantly increased at the lumbar spinal dorsal horn (L4-5) 3 days and 7 days after SCI compared with the sham-control (p<.05), whereas phosphorylated p38 was co-localized with microglia. Three days after SCI, the intensity of phosphorylated p38 and Iba1 immunoreactive cells in the dorsal horn was significantly lower in the ripasudil treated groups than in the saline group. However, administration of ROCK inhibitor did not affect the numbers of microglia. Moreover, the withdrawal threshold of the ripasudil-treated rats was significantly higher than that of the saline-injected rats on 14 days and 28 days after SCI. CONCLUSIONS Our results suggest that activation of ROCK in spinal cord microglia is likely to have an important role in the activation of p38 MAPK, which has been considered as a key molecule that switches on neuropathic pain after SCI. Inhibition of ROCK signaling may offer a means in developing a novel neuropathic pain treatment after SCI. It may help patients with neuropathic pain after SCI. CLINICAL SIGNIFICANCE The findings in the present study regarding intracellular mechanisms suggest that modulation of ROCK signaling may be a focus for novel treatment for neuropathic pain after SCI.
Collapse
Affiliation(s)
- Kazuya Kishima
- Department of Orthopaedic Surgery, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan; Department of Anatomy and Neuroscience, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan
| | - Toshiya Tachibana
- Department of Orthopaedic Surgery, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan.
| | - Hiroki Yamanaka
- Department of Anatomy and Neuroscience, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan
| | - Kimiko Kobayashi
- Department of Anatomy and Neuroscience, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan
| | - Masamichi Okubo
- Department of Anatomy and Neuroscience, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan
| | - Keishi Maruo
- Department of Orthopaedic Surgery, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan
| | - Koichi Noguchi
- Department of Anatomy and Neuroscience, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan
| |
Collapse
|
6
|
Ling YTT, Pease ME, Jefferys JL, Kimball EC, Quigley HA, Nguyen TD. Pressure-Induced Changes in Astrocyte GFAP, Actin, and Nuclear Morphology in Mouse Optic Nerve. Invest Ophthalmol Vis Sci 2020; 61:14. [PMID: 32910133 PMCID: PMC7488631 DOI: 10.1167/iovs.61.11.14] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 08/12/2020] [Indexed: 12/17/2022] Open
Abstract
Purpose To conduct quantitative analysis of astrocytic glial fibrillary acidic protein (GFAP), actin and nuclei distribution in mouse optic nerve (ON) and investigate changes in the measured features after 3 days of ocular hypertension (OHT). Method Serial cross-sections of 3-day microbead-induced OHT and control ONs were fluorescently labelled and imaged using confocal microscope. Eighteen structural features were measured from the acquired images, including GFAP coverage, actin area fraction, process thickness, and aspect ratio of cell nucleus. The measured features were analyzed for variations with axial locations along ON and radial zones transverse to ON, as well as for the correlations with degree of intraocular pressure (IOP) change. Results The most significant changes in structural features after 3-day OHT occurred in the unmyelinated ON region (R1), and the changes were greater with greater IOP elevation. Although the GFAP, actin, axonal, and ON areas all increased in 3-day OHT ONs in R1 (P ≤ 0.004 for all), the area fraction of GFAP actually decreased (P = 0.02), the actin area fraction was stable and individual axon compartments were unchanged in size. Within R1, the number of nuclear clusters increased (P < 0.001), but the mean size of nuclear clusters was smaller (P = 0.02) and the clusters became rounder (P < 0.001). In all cross-sections of control ONs, astrocytic processes were thickest in the rim zone compared with the central and peripheral zones (P ≤ 0.002 for both), whereas the overall process width in R1 decreased after 3 days of OHT (P < 0.001). Conclusions The changes in structure elucidated IOP-generated alterations that underlie astrocyte mechanotranslational responses relevant to glaucoma.
Collapse
Affiliation(s)
- Yik Tung Tracy Ling
- Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, Maryland, United States
| | - Mary E. Pease
- Wilmer Ophthalmological Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, United States
| | - Joan L. Jefferys
- Wilmer Ophthalmological Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, United States
| | - Elizabeth C. Kimball
- Wilmer Ophthalmological Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, United States
| | - Harry A. Quigley
- Wilmer Ophthalmological Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, United States
| | - Thao D. Nguyen
- Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, Maryland, United States
| |
Collapse
|
7
|
Planas-Fontánez TM, Dreyfus CF, Saitta KS. Reactive Astrocytes as Therapeutic Targets for Brain Degenerative Diseases: Roles Played by Metabotropic Glutamate Receptors. Neurochem Res 2020; 45:541-550. [PMID: 31983009 PMCID: PMC7058558 DOI: 10.1007/s11064-020-02968-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 01/13/2020] [Accepted: 01/18/2020] [Indexed: 02/06/2023]
Abstract
Astrocytes are well known to play critical roles in the development and maintenance of the central nervous system (CNS). Moreover, recent reports indicate that these cells are heterogeneous with respect to the molecules they express and the functions they exhibit in the quiescent or activated state. Because astrocytes also contribute to pathology, promising new results raise the possibility of manipulating specific astroglial populations for therapeutic roles. In this mini-review, we highlight the function of metabotropic glutamate receptors (mGluRs), in particular mGluR3 and mGluR5, in reactive astrocytes and relate these to three degenerative CNS diseases: multiple sclerosis, Alzheimer's disease and Amyotrophic Lateral Sclerosis. Previous studies demonstrate that effects of these receptors may be beneficial, but this varies depending on the subtype of receptor, the state of the astrocytes, and the specific disease to which they are exposed. Elucidating the role of mGluRs on astrocytes at specific times during development and disease will provide novel insights in understanding how to best use these to serve as therapeutic targets.
Collapse
Affiliation(s)
- Talia M. Planas-Fontánez
- grid.430387.b0000 0004 1936 8796Joint Graduate Program in Toxicology, Rutgers, The State University of New Jersey, Piscataway, NJ USA ,grid.430387.b0000 0004 1936 8796Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ USA
| | - Cheryl F. Dreyfus
- grid.430387.b0000 0004 1936 8796Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ USA ,grid.430387.b0000 0004 1936 8796Robert Wood Johnson Medical School, 683 Hoes Lane West, Room 361, Piscataway, NJ 08854 USA
| | - Kyle S. Saitta
- grid.430387.b0000 0004 1936 8796Joint Graduate Program in Toxicology, Rutgers, The State University of New Jersey, Piscataway, NJ USA ,grid.430387.b0000 0004 1936 8796Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ USA
| |
Collapse
|
8
|
Mezzomo NJ, Fontana BD, Kalueff AV, Barcellos LJ, Rosemberg DB. Understanding taurine CNS activity using alternative zebrafish models. Neurosci Biobehav Rev 2018; 90:471-485. [DOI: 10.1016/j.neubiorev.2018.04.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
9
|
Zorec R, Parpura V, Verkhratsky A. Preventing neurodegeneration by adrenergic astroglial excitation. FEBS J 2018; 285:3645-3656. [PMID: 29630772 DOI: 10.1111/febs.14456] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 03/17/2018] [Accepted: 03/28/2018] [Indexed: 01/22/2023]
Abstract
Impairment of the main noradrenergic nucleus of the human brain, the locus coeruleus (LC), which has been discovered in 1784, represents one of defining factors of neurodegenerative diseases progression. Projections of LC neurons release noradrenaline/norepinephrine (NA), which stimulates astrocytes, homeostatic neuroglial cells enriched with adrenergic receptors. There is a direct correlation between the reduction in noradrenergic innervations and cognitive decline associated with ageing and neurodegenerative diseases. It is, therefore, hypothesized that the resilience of LC neurons to degeneration influences the neural reserve that in turn determines cognitive decline. Deficits in the noradrenergic innervation of the brain might be reversed or restrained by increasing the activity of existing LC neurons, transplanting noradrenergic neurons, and/or using drugs that mimic the activity of NA on astroglia. Here, these strategies are discussed with the aim to understand how astrocytes integrate neuronal network activity in the brain information processing in health and disease.
Collapse
Affiliation(s)
- Robert Zorec
- Laboratory of Neuroendocrinology and Molecular Cell Physiology, Institute of Pathophysiology, University of Ljubljana, Slovenia.,Celica, BIOMEDICAL, Ljubljana, Slovenia
| | - Vladimir Parpura
- Department of Neurobiology, Civitan International Research Center and Center for Glial Biology in Medicine, Evelyn F. McKnight Brain Institute, Atomic Force Microscopy & Nanotechnology Laboratories, University of Alabama, Birmingham, AL, USA
| | - Alexei Verkhratsky
- Laboratory of Neuroendocrinology and Molecular Cell Physiology, Institute of Pathophysiology, University of Ljubljana, Slovenia.,Celica, BIOMEDICAL, Ljubljana, Slovenia.,Faculty of Biology, Medicine and Health, The University of Manchester, UK.,Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.,Department of Neurosciences, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain
| |
Collapse
|
10
|
Adamchik DA, Matrosov VV, Kazantsev VB. Emergence of Relaxation Oscillations in Neurons Interacting With Non-stationary Ambient GABA. Front Comput Neurosci 2018; 12:19. [PMID: 29674960 PMCID: PMC5895729 DOI: 10.3389/fncom.2018.00019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 03/12/2018] [Indexed: 11/29/2022] Open
Abstract
Dynamics of a homogeneous neural population interacting with active extracellular medium were considered. The corresponding mathematical model was tuned specifically to describe the behavior of interneurons with tonic GABA conductance under the action of non-stationary ambient GABA. The feedback provided by the GABA mediated transmembrane current enriched the repertoire of population activity by enabling the oscillatory behavior. This behavior appeared in the form of relaxation oscillations which can be considered as a specific type of brainwaves.
Collapse
|
11
|
Zorec R, Parpura V, Verkhratsky A. Astroglial vesicular network: evolutionary trends, physiology and pathophysiology. Acta Physiol (Oxf) 2018; 222. [PMID: 28665546 DOI: 10.1111/apha.12915] [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: 04/30/2017] [Revised: 05/17/2017] [Accepted: 06/24/2017] [Indexed: 12/13/2022]
Abstract
Intracellular organelles, including secretory vesicles, emerged when eukaryotic cells evolved some 3 billion years ago. The primordial organelles that evolved in Archaea were similar to endolysosomes, which developed, arguably, for specific metabolic tasks, including uptake, metabolic processing, storage and disposal of molecules. In comparison with prokaryotes, cell volume of eukaryotes increased by several orders of magnitude and vesicle traffic emerged to allow for communication between distant intracellular locations. Lysosomes, first described in 1955, a prominent intermediate of endo- and exocytotic pathways, operate virtually in all eukaryotic cells including astroglia, the most heterogeneous type of homeostatic glia in the central nervous system. Astrocytes support neuronal network activity in particular through elaborated secretion, based on a complex intracellular vesicle network dynamics. Deranged homeostasis underlies disease and astroglial vesicle traffic contributes to the pathophysiology of neurodegenerative (Alzheimer's disease, Huntington's disease), neurodevelopmental diseases (intellectual deficiency, Rett's disease) and neuroinfectious (Zika virus) disorders. This review addresses astroglial cell-autonomous vesicular traffic network, as well as its into primary and secondary vesicular network defects in diseases, and considers this network as a target for developing new therapies for neurological conditions.
Collapse
Affiliation(s)
- R. Zorec
- Laboratory of Neuroendocrinology and Molecular Cell Physiology; Institute of Pathophysiology; University of Ljubljana; Ljubljana Slovenia
- Celica; BIOMEDICAL; Ljubljana Slovenia
| | - V. Parpura
- Department of Neurobiology; Civitan International Research Center and Center for Glial Biology in Medicine; Evelyn F. McKnight Brain Institute; Atomic Force Microscopy and Nanotechnology Laboratories; University of Alabama; Birmingham AL USA
| | - A. Verkhratsky
- Laboratory of Neuroendocrinology and Molecular Cell Physiology; Institute of Pathophysiology; University of Ljubljana; Ljubljana Slovenia
- Celica; BIOMEDICAL; Ljubljana Slovenia
- Faculty of Biology; Medicine and Health; The University of Manchester; Manchester UK
- Achucarro Center for Neuroscience; IKERBASQUE; Basque Foundation for Science; Bilbao Spain
- Department of Neurosciences; University of the Basque Country UPV/EHU and CIBERNED; Leioa Spain
| |
Collapse
|
12
|
Understanding taurine CNS activity using alternative zebrafish models. Neurosci Biobehav Rev 2017; 83:525-539. [PMID: 28916270 DOI: 10.1016/j.neubiorev.2017.09.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 08/08/2017] [Accepted: 09/02/2017] [Indexed: 12/11/2022]
Abstract
Taurine is a highly abundant "amino acid" in the brain. Despite the potential neuroactive role of taurine in vertebrates has long been recognized, the underlying molecular mechanisms related to its pleiotropic effects in the brain remain poorly understood. Due to the genetic tractability, rich behavioral repertoire, neurochemical conservation, and small size, the zebrafish (Danio rerio) has emerged as a powerful candidate for neuropsychopharmacology investigation and in vivo drug screening. Here, we summarize the main physiological roles of taurine in mammals, including neuromodulation, osmoregulation, membrane stabilization, and antioxidant action. In this context, we also highlight how zebrafish models of brain disorders may present interesting approaches to assess molecular mechanisms underlying positive effects of taurine in the brain. Finally, we outline recent advances in zebrafish drug screening that significantly improve neuropsychiatric translational researches and small molecule screens.
Collapse
|
13
|
Tateda S, Kanno H, Ozawa H, Sekiguchi A, Yahata K, Yamaya S, Itoi E. Rapamycin suppresses microglial activation and reduces the development of neuropathic pain after spinal cord injury. J Orthop Res 2017; 35:93-103. [PMID: 27279283 DOI: 10.1002/jor.23328] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 06/05/2016] [Indexed: 02/04/2023]
Abstract
Rapamycin is an inhibitor of the mammalian target of rapamycin (mTOR) signaling pathway, plays an important role in multiple cellular functions. Our previous study showed rapamycin treatment in acute phase reduced the neural tissue damage and locomotor impairment after spinal cord injury (SCI). However, there has been no study to investigate the therapeutic effect of rapamycin on neuropathic pain after SCI. In this study, we examined whether rapamycin reduces neuropathic pain following SCI in mice. We used a mouse model of thoracic spinal cord contusion injury, and divided the mice into the rapamycin-treated and the vehicle-treated groups. The rapamycin-treated mice were intraperitoneally injected with rapamycin (1 mg/kg) 4 h after SCI. The rapamycin treatment suppressed phosphorylated-p70S6K in the injured spinal cord that indicated inhibition of mTOR. The rapamycin treatment significantly improved not only locomotor function, but also mechanical and thermal hypersensitivity in the hindpaws after SCI. In an immunohistochemical analysis, Iba-1-stained microglia in the lumbar spinal cord was significantly decreased in the rapamycin-treated mice. In addition, the activity of p38 MAPK in the lumbar spinal cord was significantly attenuated by rapamycin treatment. Furthermore, phosphorylated-p38 MAPK-positive microglia was relatively decreased in the rapamycin-treated mice. These results indicated rapamycin administration in acute phase to reduce secondary neural tissue damage can contribute to the suppression of the microglial activation in the lumbar spinal cord and attenuate the development of neuropathic pain after SCI. The present study first demonstrated that rapamycin has significant therapeutic potential to reduce the development of neuropathic pain following SCI. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:93-103, 2017.
Collapse
Affiliation(s)
- Satoshi Tateda
- Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Miyagi, Japan
| | - Haruo Kanno
- Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Miyagi, Japan
| | - Hiroshi Ozawa
- Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Miyagi, Japan
| | - Akira Sekiguchi
- Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Miyagi, Japan
| | - Kenichiro Yahata
- Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Miyagi, Japan
| | - Seiji Yamaya
- Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Miyagi, Japan
| | - Eiji Itoi
- Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Miyagi, Japan
| |
Collapse
|
14
|
Klapal L, Igelhorst BA, Dietzel-Meyer ID. Changes in Neuronal Excitability by Activated Microglia: Differential Na(+) Current Upregulation in Pyramid-Shaped and Bipolar Neurons by TNF-α and IL-18. Front Neurol 2016; 7:44. [PMID: 27065940 PMCID: PMC4812774 DOI: 10.3389/fneur.2016.00044] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 03/14/2016] [Indexed: 12/22/2022] Open
Abstract
Microglia are activated during pathological events in the brain and are capable of releasing various types of inflammatory cytokines. Here, we demonstrate that the addition of 5% microglia activated by 1 μg/ml lipopolysaccharides (LPS) to hippocampal cultures upregulates Na+ current densities (INavD) of bipolar as well as pyramid-shaped neurons, thereby increasing their excitability. Deactivation of microglia by the addition of 10 ng/ml transforming growth factor-β (TGF-β) decreases INavD below control levels suggesting that the residual activated microglial cells influence neuronal excitability in control cultures. Preincubation of hippocampal cultures with 10 ng/ml tumor necrosis factor-α (TNF-α), a major cytokine released by activated microglia, upregulated INavD significantly by ~30% in bipolar cells, whereas in pyramid-shaped cells, the upregulation only reached an increase of ~14%. Incubation of the cultures with antibodies against either TNF-receptor 1 or 2 blocked the upregulation of INavD in bipolar cells, whereas in pyramid-shaped cells, increases in INavD were exclusively blocked by antibodies against TNF-receptor 2, suggesting that both cell types respond differently to TNF-α exposure. Since additional cytokines, such as interleukin-18 (IL-18), are released from activated microglia, we tested potential effects of IL-18 on INavD in both cell types. Exposure to 5–10 ng/ml IL-18 for 4 days increased INavD in both pyramid-shaped as well as bipolar neurons, albeit the dose–response curves were shifted to lower concentrations in bipolar cells. Our results suggest that by secretion of cytokines, microglial cells upregulate Na+ current densities in bipolar and pyramid-shaped neurons to some extent differentially. Depending on the exact cytokine composition and concentration released, this could change the balance between the activity of inhibitory bipolar and excitatory pyramid-shaped cells. Since bipolar cells show a larger upregulation of INavD in response to TNF-α as well as respond to smaller concentrations of IL-18, our results offer an explanation for the finding, that in certain conditions of brain inflammations periods of dizziness are followed by epileptic seizures.
Collapse
Affiliation(s)
- Lars Klapal
- Department of Biochemistry II, Ruhr-University Bochum , Bochum , Germany
| | - Birte A Igelhorst
- Department of Biochemistry II, Ruhr-University Bochum , Bochum , Germany
| | | |
Collapse
|
15
|
Stenovec M, Trkov S, Kreft M, Zorec R. Alterations of calcium homoeostasis in cultured rat astrocytes evoked by bioactive sphingolipids. Acta Physiol (Oxf) 2014; 212:49-61. [PMID: 24825022 DOI: 10.1111/apha.12314] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 03/13/2014] [Accepted: 05/08/2014] [Indexed: 12/14/2022]
Abstract
AIM In the brain, alterations in sphingolipid metabolism contribute to several neurological disorders; however, their effect on astrocytes is largely unknown. Here, we identified bioactive sphingolipids that affect intracellular free calcium concentration ([Ca(2+)]i), mobility of peptidergic secretory vesicles, signalling pathways involved in alterations of calcium homoeostasis and explored the relationship between the stimulus-evoked increase in [Ca(2+)]i and attenuation of vesicle mobility. METHODS Confocal time-lapse images were acquired to explore [Ca(2+)]i signals, the mobility of fluorescently tagged peptidergic vesicles and the structural integrity of the microtubules and actin filaments before and after the addition of exogenous sphingolipids to astrocytes. RESULTS Fingolimod (FTY720), a recently introduced therapeutic for multiple sclerosis, and sphingosine, a releasable constituent of membrane sphingolipids, evoked long-lasting increases in [Ca(2+)]i in the presence and absence of extracellular Ca(2+); the evoked responses were diminished in the absence of extracellular Ca(2+). Activation of phospholipase C and inositol-1,4,5-triphosphate receptors was necessary and sufficient to evoke increases in [Ca(2+)]i as revealed by the pharmacologic inhibitors; Ca(2+) flux from the extracellular space intensified these responses several fold. The lipid-evoked increases in [Ca(2+)]i coincided with the attenuated vesicle mobility. High and positive correlation between increase in [Ca(2+)]i and decrease in peptidergic vesicle mobility was confirmed independently in astrocytes exposed to evoked, transient Ca(2+) signalling triggered by purinergic and glutamatergic stimulation. CONCLUSION Exogenously added cell-permeable sphingosine-like lipids exert complex, Ca(2+)-dependent effects on astrocytes and likely alter their homeostatic function in vivo.
Collapse
Affiliation(s)
- M. Stenovec
- Celica Biomedical Center d.o.o.; Ljubljana Slovenia
- Laboratory of Neuroendocrinology-Molecular Cell Physiology; Institute of Pathophysiology; Faculty of Medicine; University of Ljubljana; Ljubljana Slovenia
| | - S. Trkov
- Celica Biomedical Center d.o.o.; Ljubljana Slovenia
- Laboratory of Neuroendocrinology-Molecular Cell Physiology; Institute of Pathophysiology; Faculty of Medicine; University of Ljubljana; Ljubljana Slovenia
| | - M. Kreft
- Celica Biomedical Center d.o.o.; Ljubljana Slovenia
- Laboratory of Neuroendocrinology-Molecular Cell Physiology; Institute of Pathophysiology; Faculty of Medicine; University of Ljubljana; Ljubljana Slovenia
- Department of Biology; CPAE; Biotechnical Faculty; University of Ljubljana; Ljubljana Slovenia
| | - R. Zorec
- Celica Biomedical Center d.o.o.; Ljubljana Slovenia
- Laboratory of Neuroendocrinology-Molecular Cell Physiology; Institute of Pathophysiology; Faculty of Medicine; University of Ljubljana; Ljubljana Slovenia
| |
Collapse
|
16
|
Potokar M, Korva M, Jorgačevski J, Avšič-Županc T, Zorec R. Tick-borne encephalitis virus infects rat astrocytes but does not affect their viability. PLoS One 2014; 9:e86219. [PMID: 24465969 PMCID: PMC3896472 DOI: 10.1371/journal.pone.0086219] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 12/11/2013] [Indexed: 12/30/2022] Open
Abstract
Tick-borne encephalitis virus (TBEV) causes one of the most dangerous human neuroinfections in Europe and Asia. To infect neurons it must cross the blood-brain-barrier (BBB), and presumably also cells adjacent to the BBB, such as astrocytes, the most abundant glial cell type. However, the knowledge about the viral infection of glial cells is fragmental. Here we studied whether TBEV infects rat astrocytes. Rats belong to an animal group serving as a TBEV amplifying host. We employed high resolution quantitative fluorescence microscopy to investigate cell entry and cytoplasmic mobility of TBEV particles along with the effect on the cell cytoskeleton and cell survival. We report that infection of astrocytes with TBEV increases with time of exposure to TBEV and that with post-infection time TBEV particles gained higher mobility. After several days of infection actin cytoskeleton was affected, but cell survival was unchanged, indicating that rat astrocytes resist TBEV-mediated cell death, as reported for other mammalian cells. Therefore, astrocytes may present an important pool of dormant TBEV infections and a new target for therapeutic intervention.
Collapse
Affiliation(s)
- Maja Potokar
- Celica Biomedical Center, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology – Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Miša Korva
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Jernej Jorgačevski
- Celica Biomedical Center, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology – Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Tatjana Avšič-Županc
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Robert Zorec
- Celica Biomedical Center, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology – Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| |
Collapse
|
17
|
Menzie J, Prentice H, Wu JY. Neuroprotective Mechanisms of Taurine against Ischemic Stroke. Brain Sci 2013; 3:877-907. [PMID: 24961429 PMCID: PMC4061860 DOI: 10.3390/brainsci3020877] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Revised: 05/14/2013] [Accepted: 05/17/2013] [Indexed: 02/02/2023] Open
Abstract
Ischemic stroke exhibits a multiplicity of pathophysiological mechanisms. To address the diverse pathophysiological mechanisms observed in ischemic stroke investigators seek to find therapeutic strategies that are multifaceted in their action by either investigating multipotential compounds or by using a combination of compounds. Taurine, an endogenous amino acid, exhibits a plethora of physiological functions. It exhibits antioxidative properties, stabilizes membrane, functions as an osmoregulator, modulates ionic movements, reduces the level of pro-inflammators, regulates intracellular calcium concentration; all of which contributes to its neuroprotective effect. Data are accumulating that show the neuroprotective mechanisms of taurine against stroke pathophysiology. In this review, we describe the neuroprotective mechanisms employed by taurine against ischemic stroke and its use in clinical trial for ischemic stroke.
Collapse
Affiliation(s)
- Janet Menzie
- Program in Integrative Biology, Florida Atlantic University, Boca Raton, FL 33431, USA.
| | - Howard Prentice
- Department of Biomedical Sciences, Florida Atlantic University, Boca Raton, FL 33431, USA.
| | - Jang-Yen Wu
- Program in Integrative Biology, Florida Atlantic University, Boca Raton, FL 33431, USA.
| |
Collapse
|
18
|
Perez-Polo JR, Rea HC, Johnson KM, Parsley MA, Unabia GC, Xu G, Infante SK, Dewitt DS, Hulsebosch CE. Inflammatory consequences in a rodent model of mild traumatic brain injury. J Neurotrauma 2013; 30:727-40. [PMID: 23360201 DOI: 10.1089/neu.2012.2650] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Mild traumatic brain injury (mTBI), particularly mild "blast type" injuries resulting from improvised exploding devices and many sport-caused injuries to the brain, result in long-term impairment of cognition and behavior. Our central hypothesis is that there are inflammatory consequences to mTBI that persist over time and, in part, are responsible for resultant pathogenesis and clinical outcomes. We used an adaptation (1 atmosphere pressure) of a well-characterized moderate-to-severe brain lateral fluid percussion (LFP) brain injury rat model. Our mild LFP injury resulted in acute increases in interleukin-1α/β and tumor necrosis factor alpha levels, macrophage/microglial and astrocytic activation, evidence of heightened cellular stress, and blood-brain barrier (BBB) dysfunction that were evident as early as 3-6 h postinjury. Both glial activation and BBB dysfunction persisted for 18 days postinjury.
Collapse
Affiliation(s)
- J Regino Perez-Polo
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas 77225, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Bi RY, Kou XX, Meng Z, Wang XD, Ding Y, Gan YH. Involvement of trigeminal ganglionic Nav1.7 in hyperalgesia of inflamed temporomandibular joint is dependent on ERK1/2 phosphorylation of glial cells in rats. Eur J Pain 2012; 17:983-94. [PMID: 23242737 DOI: 10.1002/j.1532-2149.2012.00262.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/14/2012] [Indexed: 12/31/2022]
Affiliation(s)
- R-Y. Bi
- The Third Dental Center; Peking University School and Hospital of Stomatology; Beijing; China
| | - X-X. Kou
- The Department of Orthodontics; Peking University School and Hospital of Stomatology; Beijing; China
| | - Z. Meng
- Central Laboratory and Center for Temporomandibular Disorders & Orofacial Pain; Peking University School and Hospital of Stomatology; Beijing; China
| | - X-D. Wang
- The Department of Orthodontics; Peking University School and Hospital of Stomatology; Beijing; China
| | - Y. Ding
- The Third Dental Center; Peking University School and Hospital of Stomatology; Beijing; China
| | - Y-H. Gan
- Central Laboratory and Center for Temporomandibular Disorders & Orofacial Pain; Peking University School and Hospital of Stomatology; Beijing; China
| |
Collapse
|
20
|
Porlan E, Perez-Villalba A, Delgado AC, Ferrón SR. Paracrine regulation of neural stem cells in the subependymal zone. Arch Biochem Biophys 2012; 534:11-9. [PMID: 23073070 DOI: 10.1016/j.abb.2012.10.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 09/27/2012] [Accepted: 10/05/2012] [Indexed: 12/31/2022]
Abstract
Stem cells maintain their self-renewal and multipotency capacities through a self-organizing network of transcription factors and intracellular pathways activated by extracellular signaling from the microenvironment or "niche" in which they reside in vivo. In the adult mammalian brain new neurons continue to be generated throughout life of the organisms and this lifelong process of neurogenesis is supported by a reservoir of neural stem cells in the germinal regions. The discovery of adult neurogenesis in the mammalian brain has sparked great interest in defining the conditions that guide neural stem cell (NSC) maintenance and differentiation into the great variety of neuronal and glial subtypes. Here we review current knowledge regarding the paracrine regulation provided by the components of the niche and its function, focusing on the main germinal region of the adult central nervous system (CNS), the subependymal zone (SEZ).
Collapse
Affiliation(s)
- Eva Porlan
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas, Spain
| | | | | | | |
Collapse
|
21
|
Beuckmann CT, Dernbach K, Hakvoort A, Galla HJ. A new astrocytic cell line which is able to induce a blood-brain barrier property in cultured brain capillary endothelial cells. Cytotechnology 2012; 24:11-7. [PMID: 22358592 DOI: 10.1023/a:1007936323956] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Astrocytes, a member of the glial cell family in the central nervous system, are assumed to play a crucial role in the formation of the blood-brain barrier (BBB) in vertebrates. It was shown that astrocytes induce BBB-properties in brain capillary endothelial cells (BCEC) in vitro. We now established an astroglial cell line of non-tumoral origin. The cloned cell line (A7) shows a highly increased proliferation rate and expresses the astrocytic marker glial fibrillary acidic protein. Furthermore, the clone A7 expresses S-100-protein and vimentin, which are also expressed by primary cultured astrocytes. This cell line therefore shows general astrocytic features. In addition, we were able to show that A7 cells re-induce the BBB-related marker enzyme alkaline phosphatase in BCEC, when these two cell types are co-cultured. Thus we have a cell line which can be readily cultured in large quantities, shows common astrocyte properties and is able to influence BCEC with respect to a BBB-related feature.
Collapse
Affiliation(s)
- C T Beuckmann
- Institut für Biochemie, Westfälische Wilhelms-Universität, Wilhelm-Klemm-Straße 2, D-48149, Münster, F.R, Germany
| | | | | | | |
Collapse
|
22
|
Menzie J, Pan C, Prentice H, Wu JY. Taurine and central nervous system disorders. Amino Acids 2012; 46:31-46. [DOI: 10.1007/s00726-012-1382-z] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Accepted: 07/27/2012] [Indexed: 01/28/2023]
|
23
|
Lee E, Sidoryk-Wegrzynowicz M, Yin Z, Webb A, Son DS, Aschner M. Transforming growth factor-α mediates estrogen-induced upregulation of glutamate transporter GLT-1 in rat primary astrocytes. Glia 2012; 60:1024-36. [PMID: 22488924 PMCID: PMC3353324 DOI: 10.1002/glia.22329] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 02/28/2012] [Indexed: 01/02/2023]
Abstract
Glutamate transporter-1 (GLT-1) plays a central role in preventing excitotoxicity by removing excess glutamate from the synaptic clefts. 17β-Estradiol (E2) and tamoxifen (TX), a selective estrogen receptor (ER) modulator, afford neuroprotection in a range of experimental models. However, the mechanisms that mediate E2 and TX neuroprotection have yet to be elucidated. We tested the hypothesis that E2 and TX enhance GLT-1 function by increasing transforming growth factor (TGF)-α expression and, thus, attenuate manganese (Mn)-induced impairment in astrocytic GLT-1 expression and glutamate uptake in rat neonatal primary astrocytes. The results showed that E2 (10 nM) and TX (1 μM) increased GLT-1 expression and reversed the Mn-induced reduction in GLT-1, both at the mRNA and protein levels. E2/TX also concomitantly reversed the Mn-induced inhibition of astrocytic glutamate uptake. E2/TX activated the GLT-1 promoter and attenuated the Mn-induced repression of the GLT-1 promoter in astrocytes. TGF-α knockdown (siRNA) abolished the E2/TX effect on GLT-1 expression, and inhibition of epidermal growth factor receptor (TGF-α receptor) suppressed the effect of E2/TX on GLT-1 expression and GLT-1 promoter activity. E2/TX also increased TGF-α mRNA and protein levels with a concomitant increase in astrocytic glutamate uptake. All ERs (ER-α, ER-β, and G protein-coupled receptor 30) were involved in mediating E2 effects on the regulation of TGF-α, GLT-1, and glutamate uptake. These results indicate that E2/TX increases GLT-1 expression in astrocytes via TGF-α signaling, thus offering an important putative target for the development of novel therapeutics for neurological disorders.
Collapse
Affiliation(s)
- Eunsook Lee
- Department of Physiology, Meharry Medical College, Nashville, TN 37208, USA.
| | | | | | | | | | | |
Collapse
|
24
|
Santello M, Calì C, Bezzi P. Gliotransmission and the tripartite synapse. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 970:307-31. [PMID: 22351062 DOI: 10.1007/978-3-7091-0932-8_14] [Citation(s) in RCA: 145] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
In the last years, the classical view of glial cells (in particular of astrocytes) as a simple supportive cell for neurons has been replaced by a new vision in which glial cells are active elements of the brain. Such a new vision is based on the existence of a bidirectional communication between astrocytes and neurons at synaptic level. Indeed, perisynaptic processes of astrocytes express active G-protein-coupled receptors that are able (1) to sense neurotransmitters released from the synapse during synaptic activity, (2) to increase cytosolic levels of calcium, and (3) to stimulate the release of gliotransmitters that in turn can interact with the synaptic elements. The mechanism(s) by which astrocytes can release gliotransmitter has been extensively studied during the last years. Many evidences have suggested that a fraction of astrocytes in situ release neuroactive substances both with calcium-dependent and calcium-independent mechanism(s); whether these mechanisms coexist and under what physiological or pathological conditions they occur, it remains unclear. However, the calcium-dependent exocytotic vesicular release has received considerable attention due to its potential to occur under physiological conditions via a finely regulated way. By releasing gliotransmitters in millisecond time scale with a specific vesicular apparatus, astrocytes can integrate and process synaptic information and control or modulate synaptic transmission and plasticity.
Collapse
Affiliation(s)
- Mirko Santello
- DBCM, Department of Physiology, University of Bern, Bühlplatz 5, 3012 Bern, Switzerland
| | | | | |
Collapse
|
25
|
Potokar M, Lacovich V, Chowdhury HH, Kreft M, Zorec R. Rab4 and Rab5 GTPase are required for directional mobility of endocytic vesicles in astrocytes. Glia 2012; 60:594-604. [PMID: 22279005 DOI: 10.1002/glia.22293] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Accepted: 12/16/2011] [Indexed: 11/07/2022]
Abstract
Rab4 and Rab5 GTPases are key players in the regulation of endocytosis. Although their role has been studied intensively in the past, it is still unclear how they regulate vesicle mobility. In particular, in astrocytes, the most abundant glial cells in the brain, vesicles have been shown to exhibit nondirectional and directional mobility, which can be intermittent, but the underlying switching mechanisms are not known. By using quantitative imaging, we studied the dynamics of single vesicle movements in astrocytes in real time, by transfecting them with different GDP- and GTP-locked mutants of Rab4 and Rab5. Along with the localization of Rab4 and Rab5 on early and late endocytic compartments, we measured the apparent vesicle size by monitoring the area of fluorescent puncta and determined the patterns of vesicle mobility in the presence of wild-type and Rab mutants. Dominant-negative and dominant-positive mutants, Rab4 S22N, Rab5 S34N and Rab4 Q67L, Rab5 Q79L, induced an increase in the apparent vesicle size, especially Rab5 mutants. These mutants also significantly reduced vesicle mobility in terms of vesicle track length, maximal displacement, and speed. In addition, significant reductions in the fraction of vesicles exhibiting directional mobility were observed in cells expressing Rab4 S22N, Rab4 Q67L, Rab5 S34N, and Rab5 Q79L. Our data indicate that changes in the GDP-GTP switch apparently not only affect fusion events in endocytosis and recycling, as already proposed, but also affect the molecular interactions determining directional vesicle mobility, likely involving motor proteins and the cytoskeleton.
Collapse
Affiliation(s)
- Maja Potokar
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
| | | | | | | | | |
Collapse
|
26
|
Hulsebosch CE. Special Issue on microglia and chronic pain. Exp Neurol 2012; 234:253-4. [DOI: 10.1016/j.expneurol.2012.01.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 01/08/2012] [Indexed: 10/14/2022]
|
27
|
Gwak YS, Hulsebosch CE. Neuronal hyperexcitability: a substrate for central neuropathic pain after spinal cord injury. Curr Pain Headache Rep 2012; 15:215-22. [PMID: 21387163 DOI: 10.1007/s11916-011-0186-2] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Neuronal hyperexcitability produces enhanced pain transmission in the spinal dorsal horn after spinal cord injury (SCI). Spontaneous and evoked neuronal excitability normally are well controlled by neural circuits. However, SCI produces maladaptive synaptic circuits in the spinal dorsal horn that result in neuronal hyperexcitability. After SCI, activated primary afferent neurons produce enhanced release of glutamate, neuropeptides, adenosine triphosphate, and proinflammatory cytokines, which are known to be major components for pain transmission in the spinal dorsal horn. Enhanced neurochemical events contribute to neuronal hyperexcitability, and neuroanatomical changes also contribute to maladaptive synaptic circuits and neuronal hyperexcitability. These neurochemical and neuroanatomical changes produce enhanced cellular signaling cascades that ensure persistently enhanced pain transmission. This review describes altered neurochemical and neuroanatomical contributions on neuronal hyperexcitability in the spinal dorsal horn, which serve as substrates for central neuropathic pain after SCI.
Collapse
Affiliation(s)
- Young Seob Gwak
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1043, USA
| | | |
Collapse
|
28
|
Abstract
Astrocytes were identified about 150 years ago, and, for the longest time, were considered to be supporting cells in the brain providing trophic, metabolic, and structural support for neural networks. Research in the last 2 decades has uncovered many novel molecules in astrocytes and the finding that astrocytes communicate with neurons via Ca2+ signaling, which leads to release of chemical transmitters, termed gliotransmitters, has led to renewed interest in their biology. This chapter will briefly review the unique morphology and molecular properties of astrocytes. The reader will be introduced to the role of astrocytes in blood-brain barrier (BBB) maintenance, in Ca2+ signaling, in synaptic transmission, in CNS synaptogenesis, and as neural progenitor cells. Mention is also made of the diseases in which astrocyte dysfunction has a role.
Collapse
Affiliation(s)
- Sukriti Nag
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| |
Collapse
|
29
|
Abstract
Astrocytes are glial cells, which play a significant role in a number of processes, including the brain energy metabolism. Their anatomical position between blood vessels and neurons make them an interface for effective glucose uptake from blood. After entering astrocytes, glucose can be involved in different metabolic pathways, e.g. in glycogen production. Glycogen in the brain is localized mainly in astrocytes and is an important energy source in hypoxic conditions and normal brain functioning. The portion of glucose metabolized into glycogen molecules in astrocytes is as high as 40%. It is thought that the release of gliotransmitters (such as glutamate, neuroactive peptides and ATP) into the extracellular space by regulated exocytosis supports a significant part of communication between astrocytes and neurons. On the other hand, neurotransmitter action on astrocytes has a significant role in brain energy metabolism. Therefore, understanding the astrocytes energy metabolism may help understanding neuron-astrocyte interactions.
Collapse
Affiliation(s)
- Mateja Prebil
- Laboratory of Neuroendocrinology and Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Slovenia
| | | | | | | |
Collapse
|
30
|
Affiliation(s)
- Makoto Tsuda
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University
| | - Hidetoshi Tozaki-Saitoh
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University
| | - Kazuhide Inoue
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University
| |
Collapse
|
31
|
Sidoryk-Wegrzynowicz M, Wegrzynowicz M, Lee E, Bowman AB, Aschner M. Role of astrocytes in brain function and disease. Toxicol Pathol 2010; 39:115-23. [PMID: 21075920 DOI: 10.1177/0192623310385254] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Astrocytes assume multiple roles in maintaining an optimally suited milieu for neuronal function. Select astrocytic functions include the maintenance of redox potential, the production of trophic factors, the regulation of neurotransmitter and ion concentrations, and the removal of toxins and debris from the cerebrospinal fluid (CSF). Impairments in these and other functions, as well as physiological reactions of astrocytes to injury, can trigger or exacerbate neuronal dysfunction. This review addresses select metabolic interactions between neurons and astrocytes and emphasizes the role of astrocytes in mediating and amplifying the progression of several neurodegenerative disorders, such as Parkinson's disease (PD), hepatic encephalopathy (HE), hyperammonemia (HA), Alzheimer's disease (AD), and ischemia.
Collapse
|
32
|
Potokar M, Stenovec M, Gabrijel M, Li L, Kreft M, Grilc S, Pekny M, Zorec R. Intermediate filaments attenuate stimulation-dependent mobility of endosomes/lysosomes in astrocytes. Glia 2010; 58:1208-19. [PMID: 20544856 DOI: 10.1002/glia.21000] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Intermediate filament (IF) proteins upregulation is a hallmark of astrocyte activation and reactive gliosis, but its pathophysiological implications remain incompletely understood. A recently reported association between IFs and directional mobility of peptidergic vesicles allows us to hypothesize that IFs affect vesicle dynamics and exocytosis-mediated astrocyte communication with neighboring cells. Here, we ask whether the trafficking of recycling vesicles (i.e., those fused to and then retrieved from the plasma membrane) and endosomes/lysosomes depends on IFs. Recycling vesicles were labeled by antibodies against vesicle glutamate transporter 1 (VGLUT1) and atrial natriuretic peptide (ANP), respectively, and by lysotracker, which labels endosomes/lysosomes. Quantitative fluorescence microscopy was used to monitor the mobility of labeled vesicles in astrocytes, derived from either wild-type (WT) mice or mice deficient in glial fibrillary acidic protein and vimentin (GFAP(-/-)Vim(-/-)), the latter lacking astrocyte IFs. Stimulation with ionomycin or ATP enhanced the mobility of VGLUT1-positive vesicles and reduced the mobility of ANP-positive vesicles in WT astrocytes. In GFAP(-/-)Vim(-/-) astrocytes, both vesicle types responded to stimulation, but the relative increase in mobility of VGLUT1-positive vesicles was more prominent compared with nonstimulated cells, whereas the stimulation-dependent attenuation of ANP-positive vesicles mobility was reduced compared with nonstimulated cells. The mobility of endosomes/lysosomes decreased following stimulation in WT astrocytes. However, in GFAP(-/-)Vim(-/-) astrocytes, a small increase in the mobility of endosomes/lysosomes was observed. These findings show that astrocyte IFs differentially affect the stimulation-dependent mobility of vesicles. We propose that upregulation of IFs in pathologic states may alter the function of astrocytes by deregulating vesicle trafficking.
Collapse
|
33
|
Long-Term Primary Culture of Highly-Pure Rat Embryonic Hippocampal Neurons of Low-Density. Neurochem Res 2010; 35:1333-42. [DOI: 10.1007/s11064-010-0189-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/05/2010] [Indexed: 11/26/2022]
|
34
|
Trafficking of astrocytic vesicles in hippocampal slices. Biochem Biophys Res Commun 2009; 390:1192-6. [PMID: 19879240 DOI: 10.1016/j.bbrc.2009.10.119] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2009] [Accepted: 10/23/2009] [Indexed: 01/23/2023]
Abstract
The increasingly appreciated role of astrocytes in neurophysiology dictates a thorough understanding of the mechanisms underlying the communication between astrocytes and neurons. In particular, the uptake and release of signaling substances into/from astrocytes is considered as crucial. The release of different gliotransmitters involves regulated exocytosis, consisting of the fusion between the vesicle and the plasma membranes. After fusion with the plasma membrane vesicles may be retrieved into the cytoplasm and may continue to recycle. To study the mobility implicated in the retrieval of secretory vesicles, these structures have been previously efficiently and specifically labeled in cultured astrocytes, by exposing live cells to primary and secondary antibodies. Since the vesicle labeling and the vesicle mobility properties may be an artifact of cell culture conditions, we here asked whether the retrieving exocytotic vesicles can be labeled in brain tissue slices and whether their mobility differs to that observed in cell cultures. We labeled astrocytic vesicles and recorded their mobility with two-photon microscopy in hippocampal slices from transgenic mice with fluorescently tagged astrocytes (GFP mice) and in wild-type mice with astrocytes labeled by Fluo4 fluorescence indicator. Glutamatergic vesicles and peptidergic granules were labeled by the anti-vesicular glutamate transporter 1 (vGlut1) and anti-atrial natriuretic peptide (ANP) antibodies, respectively. We report that the vesicle mobility parameters (velocity, maximal displacement and track length) recorded in astrocytes from tissue slices are similar to those reported previously in cultured astrocytes.
Collapse
|
35
|
Remote astrocytic and microglial activation modulates neuronal hyperexcitability and below-level neuropathic pain after spinal injury in rat. Neuroscience 2009; 161:895-903. [PMID: 19332108 DOI: 10.1016/j.neuroscience.2009.03.055] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Revised: 02/17/2009] [Accepted: 03/20/2009] [Indexed: 11/22/2022]
Abstract
In this study, we evaluated whether astrocytic and microglial activation mediates below-level neuropathic pain following spinal cord injury. Male Sprague-Dawley (225-250 g) rats were given low thoracic (T13) spinal transverse hemisection and behavioral, electrophysiological and immunohistochemical methods were used to examine the development and maintenance of below-level neuropathic pain. On postoperation day 28, both hind limbs showed significantly decreased paw withdrawal thresholds and thermal latencies as well as hyperexcitability of lumbar (L4-5) spinal wide dynamic range (WDR) neurons on both sides of spinal dorsal horn compared to sham controls (* P<0.05). Intrathecal treatment with propentofylline (PPF, 10 mM) for 7 consecutive days immediately after spinal injury attenuated the development of mechanical allodynia and thermal hyperalgesia in both hind limbs in a dose-related reduction compared to vehicle treatments (* P<0.05). Intrathecal treatment with single injections of PPF at 28 days after spinal injury, attenuated the existing mechanical allodynia and thermal hyperalgesia in both hind limbs in a dose related reduction (* P<0.05). In electrophysiological studies, topical treatment of 10 mM PPF onto the spinal surface attenuated the neuronal hyperexcitability in response to mechanical stimuli. In immunohistochemical studies, astrocytes and microglia in rats with spinal hemisection showed significantly increased GFAP and OX-42 expression in both superficial and deep dorsal horns in the lumbar spinal dorsal horn compared to sham controls (* P<0.05) that was prevented in a dose-related manner by PPF. In conclusion, our present data support astrocytic and microglial activation that contributes to below-level central neuropathic pain following spinal cord injury.
Collapse
|
36
|
Norenberg MD, Rama Rao KV, Jayakumar AR. Signaling factors in the mechanism of ammonia neurotoxicity. Metab Brain Dis 2009; 24:103-17. [PMID: 19104923 DOI: 10.1007/s11011-008-9113-6] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2008] [Accepted: 10/28/2008] [Indexed: 02/08/2023]
Abstract
Mechanisms involved in hepatic encephalopathy (HE) still remain poorly understood. It is generally accepted that ammonia plays a major role in this disorder, and that astrocytes represent the principal target of ammonia neurotoxicity. In recent years, studies from several laboratories have uncovered a number of factors and pathways that appear to be critically involved in the pathogenesis of this disorder. Foremost is oxidative and nitrosative stress (ONS), which is largely initiated by an ammonia-induced increase in intracellular Ca(2+). Such increase in Ca(2+) activates a number of enzymes that promote the synthesis of reactive oxygen-nitrogen species, including constitutive nitric oxide synthase, NADPH oxidase and phospholipase A2. ONS subsequently induces the mitochondrial permeability transition, and activates mitogen-activated protein kinases and the transcription factor, nuclear factor-kappaB (NF-kappaB). These factors act to generate additional reactive oxygen-nitrogen species, to phosphorylate various proteins and transcription factors, and to cause mitochondrial dysfunction. This article reviews the role of these factors in the mechanism of HE and ammonia toxicity with a focus on astrocyte swelling and glutamate uptake, which are important consequences of ammonia neurotoxicity. These pathways and factors provide attractive targets for identifying agents potentially useful in the therapy of HE and other hyperammonemic disorders.
Collapse
Affiliation(s)
- M D Norenberg
- Department of Pathology (D-33), University of Miami School of Medicine, P.O. Box 016960, Miami, FL 33101, USA.
| | | | | |
Collapse
|
37
|
Meencke HJ. Clinical neuropathology of the epilepsies in the 100 years of the ILAE (1909-2009). Epilepsia 2009; 50 Suppl 3:8-16. [DOI: 10.1111/j.1528-1167.2009.02035.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
|
38
|
Kreft M, Potokar M, Stenovec M, Pangrsic T, Zorec R. Regulated exocytosis and vesicle trafficking in astrocytes. Ann N Y Acad Sci 2009; 1152:30-42. [PMID: 19161374 DOI: 10.1111/j.1749-6632.2008.04005.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Astrocytes are increasingly viewed as crucial cells supporting and integrating brain functions. It is thought that the release of gliotransmitters into the extracellular space by regulated exocytosis supports a significant part of communication between astrocytes and neurons. Prior to exocytosis, the membrane-bound vesicles are transported through the astrocyte cytoplasm. Our recent studies have revealed new insights into vesicle trafficking in the cytoplasm of astrocytes and are reviewed in this article. The prefusion mobility of fluorescently labeled peptidergic vesicles was studied in cultured rat and mouse astrocytes. Vesicle delivery to the plasma membrane involved an interaction with the cytoskeleton, in particular with microtubules and actin filaments. Interestingly, vesicle mobility in mouse astrocytes deficient in intermediate filaments show impaired directionality of peptidergic vesicle mobility. To explore whether stimuli that increase the concentration of free calcium ions in the cytoplasm triggered vesicular ATP release from astrocytes, human embryonic kidney-293T cells transfected with a P2X(3) receptor were used as sniffers to detect ATP release. Glutamate stimulation of astrocytes was followed by an increase in the incidence of small, transient, inward currents in sniffer cells, reminiscent of postsynaptic quantal events observed at synapses. Some of the membrane-bound vesicles are retrieved from the plasma membrane to be recycled back into the cytosol. Trafficking velocity of postfusion (recycling) atrial natriuretic peptide vesicles was one order of magnitude slower in comparison to the mobility of prefusion vesicles. However, transport of all vesicle types studied required an intact cytoskeleton.
Collapse
Affiliation(s)
- Marko Kreft
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana and Celica Biomedical Center, Ljubljana, Slovenia
| | | | | | | | | |
Collapse
|
39
|
Silva C, Fuxe K, Chadi G. Involvement of astroglial fibroblast growth factor-2 and microglia in the nigral 6-OHDA parkinsonism and a possible role of glucocorticoid hormone on the glial mediated local trophism and wound repair. JOURNAL OF NEURAL TRANSMISSION. SUPPLEMENTUM 2009:185-202. [PMID: 20411778 DOI: 10.1007/978-3-211-92660-4_15] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We have observed in previous studies that 6-hydroxydopamine (6-OHDA)-induced lesions in the nigrostriatal dopamine (DA) system promote increases of the astroglial basic fibroblast growth factor (FGF-2, bFGF) synthesis in the ascending DA pathways, event that could be modified by adrenosteroid hormones. Here, we first evaluated the changes of microglial reactivity in relation to the FGF-2-mediated trophic responses in the lesioned nigrostriatal DA system. 6-OHDA was injected into the left side of the rat substantia nigra. The OX42 immunohistochemistry combined with stereology showed the time course of the microglial activation. The OX42 immunoreactivity (IR) was already increased in the pars compacta of the substantia nigra (SNc) and ventral tegmental area (VTA) 2 h after the 6-OHDA injection, peaked on day 7, and remained increased on the 14th day time-interval. In the neostriatum, OX42 immunoreactive (ir) microglial profiles increased at 24 h, peaked at 72 h, was still increased at 7 days but not 14 days after the 6-OHDA injection. Two-colour immunofluorescence analysis of the tyrosine hydroxylase (TH) and OX42 IRs revealed the presence of small patches of TH IR within the activated microglia. A decreased FGF-2 IR was seen in the cytoplasm of DA neurons of the SNc and VTA as soon as 2 h after 6-OHDA injection. The majority of the DA FGF-2 ir cells of these regions had disappeared 72 h after neurotoxin. The astroglial FGF-2 IR increased in the SNc and VTA, which peaked on day 7. Two-colour immunofluorescence and immunoperoxidase analyses of the FGF-2 and OX42 IRs revealed no FGF-2 IR within the reactive or resting microglia. Second, we have evaluated in a series of biochemical experiments whether adrenocortical manipulation can interfere with the nigral lesion and the state of local astroglial reaction, looking at the TH and GFAP levels respectively. Rats were adrenalectomized (ADX) and received a nigral 6-OHDA stereotaxical injection 2 days later and sacrificed up to 3 weeks after the DA lesion. Western blot analysis showed time-dependent decrease and elevation of TH and GFAP levels, respectively, in the lesioned versus contralateral midbrain sides, events potentiated by ADX and worsened by corticosterone replacement. ADX decreased the levels of FGF-2 protein (23 kDa isoform) in the lesioned side of the ventral midbrain compared contralaterally. The results indicate that reactive astroglia, but not reactive microglia, showed an increased FGF-2 IR in the process of DA cell degeneration induced by 6-OHDA. However, interactions between these glial cells may be relevant to the mechanisms which trigger the increased astroglial FGF-2 synthesis and thus may be related to the trophic state of DA neurons and the repair processes following DA lesion. The findings also gave further evidence that adrenocortical hormones may regulate astroglial-mediated trophic mechanisms and wound repair events in the lesioned DA system that may be relevant to the progression of Parkinson's disease.
Collapse
Affiliation(s)
- Camila Silva
- Neuroregeneration Center, Department of Neurology, University of São Paulo School of Medicine, University of São Paulo, São Paulo, Brazil
| | | | | |
Collapse
|
40
|
Calì C, Marchaland J, Spagnuolo P, Gremion J, Bezzi P. Regulated exocytosis from astrocytes physiological and pathological related aspects. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2009; 85:261-93. [PMID: 19607976 DOI: 10.1016/s0074-7742(09)85020-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Astrocytes have traditionally been considered ancillary, satellite cells of the nervous system. However, it is a very recent acquisition that glial cells generate signaling loops which are integral to the brain circuitry and participate, interactively with neuronal networks, in the processing of information. Such a conceptual breakthrough makes this field of investigation one of the hottest in neuroscience, as it calls for a revision of past theories of brain function as well as for new strategies of experimental exploration of brain function. Glial cells are electrically not excitable, and it was only the use of optical recording techniques together with calcium sensitive dyes, that allowed the chemical excitability of glial cells to become apparent. Studies using these new techniques have shown for the first time that glial cells are activated by surrounding synaptic activity and translate neuronal signals into their own calcium code. Intracellular calcium concentration([Ca2+]i) elevations in glial cells have then shown to underlie spatial transfer of information in the glial network, accompanied by release of chemical transmitters (gliotransmitters) such as glutamate and back-signaling to neurons. As a consequence, optical imaging techniques applied to cell cultures or intact tissue have become a state-of-the-art technology for studying glial cell signaling. The molecular mechanisms leading to release of "gliotransmitters," especially glutamate, from glia are under debate. Accumulating evidence clearly indicates that astrocytes secrete numerous transmitters by Ca(2+)-dependent exocytosis. This review will discuss the mechanisms underlying the release of chemical transmitters from astrocytes with a particular emphasis to the regulated exocytosis processes.
Collapse
Affiliation(s)
- Corrado Calì
- Department of Cellular Biology and Morphology (DBCM), Faculty of Medicine, University of Lausanne, rue du Bugnon 9, 1005 Lausanne, Switzerland
| | | | | | | | | |
Collapse
|
41
|
Hulsebosch CE, Hains BC, Crown ED, Carlton SM. Mechanisms of chronic central neuropathic pain after spinal cord injury. ACTA ACUST UNITED AC 2008; 60:202-13. [PMID: 19154757 DOI: 10.1016/j.brainresrev.2008.12.010] [Citation(s) in RCA: 224] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/29/2008] [Indexed: 12/25/2022]
Abstract
Not all spinal contusions result in mechanical allodynia, in which non-noxious stimuli become noxious. The studies presented use the NYU impactor at 12.5 mm drop or the Infinite Horizons Impactor (150 kdyn, 1 s dwell) devices to model spinal cord injury (SCI). Both of these devices and injury parameters, if done correctly, will result in animals with above level (forelimb), at level (trunk) and below level (hindlimb) mechanical allodynia that model the changes in evoked somatosensation experienced by the majority of people with SCI. The sections are as follows: 1) Mechanisms of remote microglial activation and pain signaling in "below-level" central pain 2) Intracellular signaling mechanisms in central sensitization in "at-level" pain 3) Peripheral sensitization contributes to "above level" injury pain following spinal cord injury and 4) Role of reactive oxygen species in central sensitization in regional neuropathic pain following SCI. To summarize, differential regional mechanisms contribute to the regional chronic pain states. We propose the importance of understanding the mechanisms in the differential regional pain syndromes after SCI in the chronic condition. Targeting regional mechanisms will be of enormous benefit to the SCI population that suffer chronic pain, and will contribute to better treatment strategies for other chronic pain syndromes.
Collapse
Affiliation(s)
- Claire E Hulsebosch
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1043, USA.
| | | | | | | |
Collapse
|
42
|
Abstract
It has long been thought that astrocytes, like other glial cells, simply provide a support mechanism for neuronal function in the healthy and inflamed central nervous system (CNS). However, recent evidence suggests that astrocytes play an active and dual role in CNS inflammatory diseases such as multiple sclerosis (MS). Astrocytes not only have the ability to enhance immune responses and inhibit myelin repair, but they can also be protective and limit CNS inflammation while supporting oligodendrocyte and axonal regeneration. The particular impact of these cells on the pathogenesis and repair of an inflammatory demyelinating process is dependent upon a number of factors, including the stage of the disease, the type and microenvironment of the lesion, and the interactions with other cell types and factors that influence their activation. In this review, we summarize recent data supporting the idea that astrocytes play a complex role in the regulation of CNS autoimmunity.
Collapse
Affiliation(s)
- A. Nair
- Department of Microbiology-Immunology and Interdepartmental Immunobiology Center, Northwestern University Fienberg School of Medicine, 303 E. Chicago Avenue, Chicago, IL 60611 USA
| | - T. J. Frederick
- Department of Microbiology-Immunology and Interdepartmental Immunobiology Center, Northwestern University Fienberg School of Medicine, 303 E. Chicago Avenue, Chicago, IL 60611 USA
| | - S. D. Miller
- Department of Microbiology-Immunology and Interdepartmental Immunobiology Center, Northwestern University Fienberg School of Medicine, 303 E. Chicago Avenue, Chicago, IL 60611 USA
| |
Collapse
|
43
|
Gliopathy ensures persistent inflammation and chronic pain after spinal cord injury. Exp Neurol 2008; 214:6-9. [PMID: 18708053 DOI: 10.1016/j.expneurol.2008.07.016] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2008] [Accepted: 07/23/2008] [Indexed: 12/12/2022]
Abstract
Research focused on improving recovery of function, including the reduction of central neuropathic pain (CNP) after spinal cord injury (SCI) is essential. After SCI, regional neuropathic pain syndromes above, at and below the level or spinal injury develop and are thought to have different mechanisms, but may share common dysfunctional glial mechanisms. Detloff et al., [Detloff, M.R., Fisher, L.C., McGaughy, V., Longbrake, E.E., Popovich, P.G., Basso, D.M., Remote activation of microglia and pro-inflammatory cytokines predict the onset and severity of below-level neuropathic pain after spinal cord injury in rats. Exp. Neurol. (2008), doi: 10.1016/j.expneurol.2008.04.009.] describe events in the lumbar region of the spinal cord after a midthoracic SCI injury, the so called "below-level" pain and compares the findings to peripheral nerve lesion findings. This commentary briefly reviews glial contributions and intracellular signaling mechanisms, both neuronal and glial, that provide the substrate for CNP after SCI, including the persistent glial production of factors that can maintain sensitization of dorsal horn neurons in segments remote from the spinal injury; ie. dorsal horn hyperexcitability to formerly non noxious stimuli that become noxious after SCI resulting in allodynia. The term "gliopathy" is proposed to describe the dysfunctional and maladaptive response of glial cells, specifically astrocytes and microglia, to neural injury that is initiated by the sudden injury induced increase in extracellular concentrations of glutamate and concomitant production of several proinflammatory molecules. It is important to understand the roles that different glia play in "gliopathy", a condition that appears to persist after SCI. Furthermore, targeted treatment of gliopathy will attenuate mechanical allodynia in both central and peripheral neuropathic pain syndromes.
Collapse
|
44
|
Ojeda SR, Lomniczi A, Sandau US. Glial-gonadotrophin hormone (GnRH) neurone interactions in the median eminence and the control of GnRH secretion. J Neuroendocrinol 2008; 20:732-42. [PMID: 18601696 DOI: 10.1111/j.1365-2826.2008.01712.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A wealth of information now exists showing that glial cells are actively involved in the cell-cell communication process generating and disseminating information within the central nervous system. In the hypothalamus, two types of glial cells, astrocytes and ependymal cells lining the latero-ventral portion of the third ventricle (known as tanycytes), regulate the secretory activity of neuroendocrine neurones. This function, initially described for astrocytes apposing magnocellular neurones, has been more recently characterised for neurones secreting gonadotrophin hormone-releasing hormone (GnRH). The available evidence suggests that glial cells of the median eminence regulate GnRH secretion via two related mechanisms. One involves the production of growth factors acting via receptors with tyrosine kinase activity. The other involves plastic rearrangements of glia-GnRH neurone adhesiveness. GnRH axons reach the median eminence, at least in part, directed by basic fibroblast growth factor. Their secretory activity is facilitated by insulin-like growth factor 1 and members of the epidermal growth factor family. A structural complement to these soluble molecules is provided by at least three cell-cell adhesion systems endowed with signalling capabilities. One of them uses the neuronal cell adhesion molecule (NCAM), another employs the synaptic cell adhesion molecule (SynCAM), and the third one consists of neuronal contactin interacting with glial receptor-like protein tyrosine phosphatase-beta. It is envisioned that, within the median eminence, soluble factors and adhesion molecules work coordinately to control delivery of GnRH to the portal vasculature.
Collapse
Affiliation(s)
- S R Ojeda
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR 97006, USA
| | | | | |
Collapse
|
45
|
Jaatinen P, Rintala J. Mechanisms of ethanol-induced degeneration in the developing, mature, and aging cerebellum. THE CEREBELLUM 2008; 7:332-47. [DOI: 10.1007/s12311-008-0034-z] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Accepted: 08/01/2007] [Indexed: 11/30/2022]
|
46
|
Potokar M, Stenovec M, Kreft M, Kreft ME, Zorec R. Stimulation inhibits the mobility of recycling peptidergic vesicles in astrocytes. Glia 2008; 56:135-44. [PMID: 17990309 DOI: 10.1002/glia.20597] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Astrocytes are increasingly viewed as playing many roles in the integration of brain function. These cells store among other gliotransmitters also neuroactive peptides in membrane bound vesicles, the trafficking and release of which, may be changed in altered conditions, therefore affecting the physiological status of neurons. In general, peptidergic membrane-bound secretory vesicles fuse with the plasma membrane in the process of exocytosis. Some of them are retrieved from the plasma membrane to be recycled back into the cytosol. The mobility of retrieving vesicles in astrocytes was not studied yet, however, understanding the mechanisms of such trafficking would highlight the communication paths between astrocytes and neurons. We labeled vesicles with antibodies against the vesicle atrial natriuretic peptide (ANP), which is stored inside secretory vesicles. ANP-vesicles in astrocytes have been proposed to enter Ca2+-dependent secretion and here we show that they are associated with synaptotagmin IV (SytIV), a regulator of exocytosis in astrocytes. Moreover, the results show that recycling ANP-vesicles are to a significant extent acidic. Their velocity (0.06+/-0.001 microm/s) is one order of magnitude lower than the velocity of vesicles trafficking to the plasma membrane (Potokar et al. (2005) Biochem Biophys Res Commun 329:678-683; Potokar et al. (2007) Traffic 8:12-20). Interestingly, ionomycin or ATP application further attenuated ANP-vesicle mobility to 0.02+/-0.002 and to 0.03+/-0.001 microm/s, respectively. In summary, the mobility of recycling peptidergic vesicles appears to be slower than the vesicle traffic to the plasma membrane and it requires an intact cytoskeleton. Physiological implications of attenuated traffic of ANP-vesicles are considered in the discussion.
Collapse
Affiliation(s)
- Maja Potokar
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloska 4, 1000 Ljubljana, Slovenia
| | | | | | | | | |
Collapse
|
47
|
Tsuda M, Hasegawa S, Inoue K. P2X receptors-mediated cytosolic phospholipase A2activation in primary afferent sensory neurons contributes to neuropathic pain. J Neurochem 2007; 103:1408-16. [PMID: 17725579 DOI: 10.1111/j.1471-4159.2007.04861.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Activation of P2X(3) and P2X(2/3) receptors (P2X(3)R/P2X(2/3)R), ionotropic ATP receptor subtypes, in primary sensory neurons is involved in neuropathic pain, a debilitating chronic pain that occurs after peripheral nerve injury. However, the underlying mechanisms remain unknown. We investigated the role of cytosolic phospholipase A(2) (cPLA(2)) as a downstream molecule that mediates the P2X(3)R/P2X(2/3)R-dependent neuropathic pain. We found that applying ATP to cultured dorsal root ganglion (DRG) neurons increased the level of Ser505-phosphorylated cPLA(2) and caused translocation of Ser505-phosphorylated cPLA(2) to the plasma membrane. The ATP-induced cPLA(2) activation was inhibited by a selective antagonist of P2X(3)R/P2X(2/3)R and by a selective inhibitor of cPLA(2). In the DRG in vivo, the number of cPLA(2)-activated neurons was strikingly increased after peripheral nerve injury but not after peripheral inflammation produced by complete Freund's adjuvant. Pharmacological blockade of P2X(3)R/P2X(2/3)R reversed the nerve injury-induced cPLA(2) activation in DRG neurons. Moreover, administering the cPLA(2) inhibitor near the DRG suppressed nerve injury-induced tactile allodynia, a hallmark of neuropathic pain. Our results suggest that P2X(3)R/P2X(2/3)R-dependent cPLA(2) activity in primary sensory neurons is a key event in neuropathic pain and that cPLA(2) might be a potential target for treating neuropathic pain.
Collapse
Affiliation(s)
- Makoto Tsuda
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Higashi, Fukuoka, Japan
| | | | | |
Collapse
|
48
|
Featherstone DE, Shippy SA. Regulation of synaptic transmission by ambient extracellular glutamate. Neuroscientist 2007; 14:171-81. [PMID: 17947494 DOI: 10.1177/1073858407308518] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Many neuroscientists assume that ambient extracellular glutamate concentrations in the nervous system are biologically negligible under nonpathological conditions. This assumption is false. Hundreds of studies over several decades suggest that ambient extracellular glutamate levels in the intact mammalian brain are approximately 0.5 to approximately 5 microM. This has important implications. Glutamate receptors are desensitized by glutamate concentrations significantly lower than needed for receptor activation; 0.5 to 5 microM of glutamate is high enough to cause constitutive desensitization of most glutamate receptors. Therefore, most glutamate receptors in vivo may be constitutively desensitized, and ambient extracellular glutamate and receptor desensitization may be potent but generally unrecognized regulators of synaptic transmission. Unfortunately, the mechanisms regulating ambient extracellular glutamate and glutamate receptor desensitization remain poorly understood and understudied.
Collapse
Affiliation(s)
- David E Featherstone
- Department of Biological Sciences, University of Illinois at Chicago 60607, USA.
| | | |
Collapse
|
49
|
Fuxe K, Dahlström A, Höistad M, Marcellino D, Jansson A, Rivera A, Diaz-Cabiale Z, Jacobsen K, Tinner-Staines B, Hagman B, Leo G, Staines W, Guidolin D, Kehr J, Genedani S, Belluardo N, Agnati LF. From the Golgi–Cajal mapping to the transmitter-based characterization of the neuronal networks leading to two modes of brain communication: Wiring and volume transmission. ACTA ACUST UNITED AC 2007; 55:17-54. [PMID: 17433836 DOI: 10.1016/j.brainresrev.2007.02.009] [Citation(s) in RCA: 182] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2007] [Revised: 02/21/2007] [Accepted: 02/27/2007] [Indexed: 10/23/2022]
Abstract
After Golgi-Cajal mapped neural circuits, the discovery and mapping of the central monoamine neurons opened up for a new understanding of interneuronal communication by indicating that another form of communication exists. For instance, it was found that dopamine may be released as a prolactin inhibitory factor from the median eminence, indicating an alternative mode of dopamine communication in the brain. Subsequently, the analysis of the locus coeruleus noradrenaline neurons demonstrated a novel type of lower brainstem neuron that monosynaptically and globally innervated the entire CNS. Furthermore, the ascending raphe serotonin neuron systems were found to globally innervate the forebrain with few synapses, and where deficits in serotonergic function appeared to play a major role in depression. We propose that serotonin reuptake inhibitors may produce antidepressant effects through increasing serotonergic neurotrophism in serotonin nerve cells and their targets by transactivation of receptor tyrosine kinases (RTK), involving direct or indirect receptor/RTK interactions. Early chemical neuroanatomical work on the monoamine neurons, involving primitive nervous systems and analysis of peptide neurons, indicated the existence of alternative modes of communication apart from synaptic transmission. In 1986, Agnati and Fuxe introduced the theory of two main types of intercellular communication in the brain: wiring and volume transmission (WT and VT). Synchronization of phasic activity in the monoamine cell clusters through electrotonic coupling and synaptic transmission (WT) enables optimal VT of monoamines in the target regions. Experimental work suggests an integration of WT and VT signals via receptor-receptor interactions, and a new theory of receptor-connexin interactions in electrical and mixed synapses is introduced. Consequently, a new model of brain function must be built, in which communication includes both WT and VT and receptor-receptor interactions in the integration of signals. This will lead to the unified execution of information handling and trophism for optimal brain function and survival.
Collapse
Affiliation(s)
- Kjell Fuxe
- Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
50
|
Pangršič T, Potokar M, Stenovec M, Kreft M, Fabbretti E, Nistri A, Pryazhnikov E, Khiroug L, Giniatullin R, Zorec R. Exocytotic release of ATP from cultured astrocytes. J Biol Chem 2007; 282:28749-28758. [PMID: 17627942 DOI: 10.1074/jbc.m700290200] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Astrocytes appear to communicate with each other as well as with neurons via ATP. However, the mechanisms of ATP release are controversial. To explore whether stimuli that increase [Ca(2+)](i) also trigger vesicular ATP release from astrocytes, we labeled ATP-containing vesicles with the fluorescent dye quinacrine, which exhibited a significant co-localization with atrial natriuretic peptide. The confocal microscopy study revealed that quinacrine-loaded vesicles displayed mainly non-directional spontaneous mobility with relatively short track lengths and small maximal displacements, whereas 4% of vesicles exhibited directional mobility. After ionomycin stimulation only non-directional vesicle mobility could be observed, indicating that an increase in [Ca(2+)](i) attenuated vesicle mobility. Total internal reflection fluorescence (TIRF) imaging in combination with epifluorescence showed that a high percentage of fluorescently labeled vesicles underwent fusion with the plasma membrane after stimulation with glutamate or ionomycin and that this event was Ca(2+)-dependent. This was confirmed by patch-clamp studies on HEK-293T cells transfected with P2X(3) receptor, used as sniffers for ATP release from astrocytes. Glutamate stimulation of astrocytes was followed by an increase in the incidence of small transient inward currents in sniffers, reminiscent of postsynaptic quantal events observed at synapses. Their incidence was highly dependent on extracellular Ca(2+). Collectively, these findings indicate that glutamate-stimulated ATP release from astrocytes was most likely exocytotic and that after stimulation the fraction of quinacrine-loaded vesicles, spontaneously exhibiting directional mobility, disappeared.
Collapse
Affiliation(s)
- Tina Pangršič
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, SI-1000 Ljubljana, Slovenia; Celica Biomedical Center, Proletarska cesta 4, SI-1000 Ljubljana, Slovenia
| | - Maja Potokar
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, SI-1000 Ljubljana, Slovenia; Celica Biomedical Center, Proletarska cesta 4, SI-1000 Ljubljana, Slovenia
| | - Matjaž Stenovec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, SI-1000 Ljubljana, Slovenia; Celica Biomedical Center, Proletarska cesta 4, SI-1000 Ljubljana, Slovenia
| | - Marko Kreft
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, SI-1000 Ljubljana, Slovenia; Celica Biomedical Center, Proletarska cesta 4, SI-1000 Ljubljana, Slovenia
| | - Elsa Fabbretti
- Neurobiology Sector, International School for Advanced Studies (SISSA), Via Beirut 2-4, 34014 Trieste, Italy
| | - Andrea Nistri
- Neurobiology Sector, International School for Advanced Studies (SISSA), Via Beirut 2-4, 34014 Trieste, Italy
| | - Evgeny Pryazhnikov
- Neuroscience Center, University of Helsinki, PO Box 56 (Viikinkaari 4), FIN-00014 Helsinki, Finland
| | - Leonard Khiroug
- Neuroscience Center, University of Helsinki, PO Box 56 (Viikinkaari 4), FIN-00014 Helsinki, Finland
| | - Rashid Giniatullin
- Neurobiology Sector, International School for Advanced Studies (SISSA), Via Beirut 2-4, 34014 Trieste, Italy
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, SI-1000 Ljubljana, Slovenia; Celica Biomedical Center, Proletarska cesta 4, SI-1000 Ljubljana, Slovenia.
| |
Collapse
|