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Glutamate and ATP: The Crossroads of Signaling and Metabolism in the Brain. GLUTAMATE AND ATP AT THE INTERFACE OF METABOLISM AND SIGNALING IN THE BRAIN 2014; 11:1-12. [DOI: 10.1007/978-3-319-08894-5_1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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52
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Okuda H, Tatsumi K, Morita S, Shibukawa Y, Korekane H, Horii-Hayashi N, Wada Y, Taniguchi N, Wanaka A. Chondroitin sulfate proteoglycan tenascin-R regulates glutamate uptake by adult brain astrocytes. J Biol Chem 2013; 289:2620-31. [PMID: 24337573 DOI: 10.1074/jbc.m113.504787] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
In our previous study, the CS-56 antibody, which recognizes a chondroitin sulfate moiety, labeled a subset of adult brain astrocytes, yielding a patchy extracellular matrix pattern. To explore the molecular nature of CS-56-labeled glycoproteins, we purified glycoproteins of the adult mouse cerebral cortex using a combination of anion-exchange, charge-transfer, and size-exclusion chromatographies. One of the purified proteins was identified as tenascin-R (TNR) by mass spectrometric analysis. When we compared TNR mRNA expression patterns with the distribution patterns of CS-56-positive cells, TNR mRNA was detected in CS-56-positive astrocytes. To examine the functions of TNR in astrocytes, we first confirmed that cultured astrocytes also expressed TNR protein. TNR knockdown by siRNA expression significantly reduced glutamate uptake in cultured astrocytes. Furthermore, expression of mRNA and protein of excitatory amino acid transporter 1 (GLAST), which is a major component of astrocytic glutamate transporters, was reduced by TNR knockdown. Our results suggest that TNR is expressed in a subset of astrocytes and contributes to glutamate homeostasis by regulating astrocytic GLAST expression.
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Affiliation(s)
- Hiroaki Okuda
- From the Departments of Anatomy and Neuroscience and
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Segawa S, Nishiura T, Furuta T, Ohsato Y, Tani M, Nishida K, Nagasawa K. Zinc is released by cultured astrocytes as a gliotransmitter under hypoosmotic stress-loaded conditions and regulates microglial activity. Life Sci 2013; 94:137-44. [PMID: 24252316 DOI: 10.1016/j.lfs.2013.11.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2013] [Revised: 10/22/2013] [Accepted: 11/07/2013] [Indexed: 12/26/2022]
Abstract
AIM Astrocytes contribute to the maintenance of brain homeostasis via the release of gliotransmitters such as ATP and glutamate. Here we examined whether zinc was released from astrocytes under stress-loaded conditions, and was involved in the regulation of microglial activity as a gliotransmitter. MAIN METHODS Hypoosmotic stress was loaded to astrocytes using balanced salt solution prepared to 214-314 mOsmol/L, and then intra- and extra-cellular zinc levels were assessed using Newport Green DCF diacetate (NG) and ICP-MS, respectively. Microglial activation by the astrocytic supernatant was assessed by their morphological changes and poly(ADP-ribose) (PAR) polymer accumulation. KEY FINDINGS Exposure of astrocytes to hypoosmotic buffer, increased the extracellular ATP level in osmolarity-dependent manners, indicating a load of hypoosmotic stress. In hypoosmotic stress-loaded astrocytes, there were apparent increases in the intra- and extra-cellular zinc levels. Incubation of microglia in the astrocytic conditioned medium transformed them into the activated "amoeboid" form and induced PAR formation. Administration of an extracellular zinc chelator, CaEDTA, to the astrocytic conditioned medium almost completely prevented the microglial activation. Treatment of astrocytes with an intracellular zinc chelator, TPEN, suppressed the hypoosmotic stress-increased intracellular, but not the extracellular, zinc level, and the increase in the intracellular zinc level was blocked partially by a nitric oxide synthase inhibitor, but not by CaEDTA, indicating that the mechanisms underlying the increases in the intra- and extra-cellular zinc levels might be different. SIGNIFICANCE These findings suggest that under hypoosmotic stress-loaded conditions, zinc is released from astrocytes and then plays a primary role in microglial activation as a gliotransmitter.
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Affiliation(s)
- Shohei Segawa
- Department of Environmental Biochemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan
| | - Takeshi Nishiura
- Department of Environmental Biochemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan
| | - Takahiro Furuta
- Department of Environmental Biochemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan
| | - Yuki Ohsato
- Department of Environmental Biochemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan
| | - Misaki Tani
- Department of Environmental Biochemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan
| | - Kentaro Nishida
- Department of Environmental Biochemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan
| | - Kazuki Nagasawa
- Department of Environmental Biochemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan.
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Kato TA, Watabe M, Kanba S. Neuron-glia interaction as a possible glue to translate the mind-brain gap: a novel multi-dimensional approach toward psychology and psychiatry. Front Psychiatry 2013; 4:139. [PMID: 24155727 PMCID: PMC3804762 DOI: 10.3389/fpsyt.2013.00139] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 10/07/2013] [Indexed: 12/28/2022] Open
Abstract
Neurons and synapses have long been the dominant focus of neuroscience, thus the pathophysiology of psychiatric disorders has come to be understood within the neuronal doctrine. However, the majority of cells in the brain are not neurons but glial cells including astrocytes, oligodendrocytes, and microglia. Traditionally, neuroscientists regarded glial functions as simply providing physical support and maintenance for neurons. Thus, in this limited role glia had been long ignored. Recently, glial functions have been gradually investigated, and increasing evidence has suggested that glial cells perform important roles in various brain functions. Digging up the glial functions and further understanding of these crucial cells, and the interaction between neurons and glia may shed new light on clarifying many unknown aspects including the mind-brain gap, and conscious-unconscious relationships. We briefly review the current situation of glial research in the field, and propose a novel translational research with a multi-dimensional model, combining various experimental approaches such as animal studies, in vitro & in vivo neuron-glia studies, a variety of human brain imaging investigations, and psychometric assessments.
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Affiliation(s)
- Takahiro A Kato
- Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University , Fukuoka , Japan ; Innovation Center for Medical Redox Navigation, Kyushu University , Fukuoka , Japan
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55
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Vilar A, de Lemos L, Patraca I, Martínez N, Folch J, Junyent F, Verdaguer E, Pallàs M, Auladell C, Camins A. Melatonin suppresses nitric oxide production in glial cultures by pro-inflammatory cytokines through p38 MAPK inhibition. Free Radic Res 2013; 48:119-28. [PMID: 24060108 DOI: 10.3109/10715762.2013.845295] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Melatonin has been shown to down-regulate inflammatory responses and provide neuroprotection. However, the mechanisms underlying the anti-inflammatory properties of melatonin are poorly understood. In the present work, we studied the modulatory effect of melatonin against pro-inflammatory cytokines in glial cell cultures. Treatment with pro-inflammatory cytokines mainly tumor necrosis factor-alpha, interleukin 1-beta, and interferon-gamma induces an increase in inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) production. Pre-treatment with melatonin produced an inhibitory effect on iNOS expression and NO production. The biochemical studies revealed that cytokine treatment favors the activation of several pathways, such as mitogen-activated protein kinases (MAPKs), STAT1, and STAT3; however, the anti-inflammatory effect of melatonin was accompanied only by a decrease in p38 MAPK activity. Likewise, SB203580 a p38 kinase inhibitor inhibits NO production. These data indicate that the anti-inflammatory action of melatonin in glial cells after stimulation with pro-inflammatory cytokines may be in part, attributable to p38 inhibition which down-regulates iNOS expression and NO production.
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Affiliation(s)
- A Vilar
- Departament de Biologia Cel·lular, Facultat de Biologia, Universitat de Barcelona , Barcelona , Spain
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56
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Rodríguez JJ, Yeh CY, Terzieva S, Olabarria M, Kulijewicz-Nawrot M, Verkhratsky A. Complex and region-specific changes in astroglial markers in the aging brain. Neurobiol Aging 2013; 35:15-23. [PMID: 23969179 DOI: 10.1016/j.neurobiolaging.2013.07.002] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Revised: 06/04/2013] [Accepted: 07/05/2013] [Indexed: 12/15/2022]
Abstract
Morphological aging of astrocytes was investigated in entorhinal cortex (EC), dentate gyrus (DG), and cornu ammonis 1 (CA1) regions of hippocampus of male SV129/C57BL6 mice of different age groups (3, 9, 18, and 24 months). Astroglial profiles were visualized by immunohistochemistry by using glial fibrillary acidic protein (GFAP), glutamine synthetase (GS), and s100β staining; these profiles were imaged using confocal or light microscopy for subsequent morphometric analysis. GFAP-positive profiles in the DG and the CA1 of the hippocampus showed progressive age-dependent hypertrophy, as indicated by an increase in surface, volume, and somata volume at 24 months of age compared with 3-month-old mice. In contrast with the hippocampal regions, aging induced a decrease in GFAP-positive astroglial profiles in the EC: the surface, volume, and cell body volume of astroglial cells at 24 months of age were decreased significantly compared with the 3-month group. The GS-positive astrocytes displayed smaller cellular surface areas at 24 months compared with 3-month-old animals in both areas of hippocampus, whereas GS-positive profiles remained unchanged in the EC of old mice. The morphometry of s100β-immunoreactive profiles revealed substantial increase in the EC, more moderate increase in the DG, and no changes in the CA1 area. Based on the morphological analysis of 3 astroglial markers, we conclude that astrocytes undergo a complex age-dependent remodeling in a brain region-specific manner.
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Affiliation(s)
- José J Rodríguez
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain; Department of Neurosciences, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain.
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Ende G, Hermann D, Demirakca T, Hoerst M, Tunc-Skarka N, Weber-Fahr W, Wichert S, Rabinstein J, Frischknecht U, Mann K, Vollstädt-Klein S. Loss of control of alcohol use and severity of alcohol dependence in non-treatment-seeking heavy drinkers are related to lower glutamate in frontal white matter. Alcohol Clin Exp Res 2013; 37:1643-9. [PMID: 23800328 DOI: 10.1111/acer.12149] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 03/06/2013] [Indexed: 12/11/2022]
Abstract
BACKGROUND The development and maintenance of alcohol use disorders (AUD) have been hypothesized to be associated with an imbalance of glutamate (GLU) homeostasis. White matter (WM) loss, especially in anterior brain regions, has been reported in alcohol dependence, which may involve disturbances in both myelin and axonal integrity. Frontal lobe dysfunction plays an important role in addiction, because it is suggested to be associated with the loss of control over substance use. This study investigated magnetic resonance spectroscopy (MRS)-detectable Glu levels in frontal WM of non-treatment-seeking heavy drinkers and its associations with AUD symptoms. METHODS Single-voxel MR spectra optimized for Glu assessment (TE 80 ms) were acquired at 3T from a frontal WM voxel in a group of heavy drinking, non-treatment-seeking subjects in comparison with a group of subjects with only light alcohol consumption. RESULTS The results corroborate previous findings of increased total choline in heavy drinking subjects. A negative association of Glu levels with severity of alcohol dependence and especially loss of control over time and amount of alcohol intake was observed. CONCLUSIONS In contrast to the rather unspecific rise in choline-containing compounds, low Glu in frontal WM may be specific for the shift from nondependent heavy drinking to dependence and does not reflect a simple effect of the amount of alcohol consumption alone.
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Affiliation(s)
- Gabriele Ende
- Department Neuroimaging , Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
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Verkhratsky A, Parpura V. Store-operated calcium entry in neuroglia. Neurosci Bull 2013; 30:125-33. [PMID: 23677809 DOI: 10.1007/s12264-013-1343-x] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2013] [Accepted: 02/14/2013] [Indexed: 11/30/2022] Open
Abstract
Neuroglial cells are homeostatic neural cells. Generally, they are electrically non-excitable and their activation is associated with the generation of complex intracellular Ca(2+) signals that define the "Ca(2+) excitability" of glia. In mammalian glial cells the major source of Ca(2+) for this excitability is the lumen of the endoplasmic reticulum (ER), which is ultimately (re)filled from the extracellular space. This occurs via store-operated Ca(2+) entry (SOCE) which is supported by a specific signaling system connecting the ER with plasmalemmal Ca(2+) entry. Here, emptying of the ER Ca(2+) store is necessary and sufficient for the activation of SOCE, and without Ca(2+) influx via SOCE the ER store cannot be refilled. The molecular arrangements underlying SOCE are relatively complex and include plasmalemmal channels, ER Ca(2+) sensors, such as stromal interaction molecule, and possibly ER Ca(2+) pumps (of the SERCA type). There are at least two sets of plasmalemmal channels mediating SOCE, the Ca(2+)-release activated channels, Orai, and transient receptor potential (TRP) channels. The molecular identity of neuroglial SOCE has not been yet identified unequivocally. However, it seems that Orai is predominantly expressed in microglia, whereas astrocytes and oligodendrocytes rely more on TRP channels to produce SOCE. In physiological conditions the SOCE pathway is instrumental for the sustained phase of the Ca(2+) signal observed following stimulation of metabotropic receptors on glial cells.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK,
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Kukkar A, Bali A, Singh N, Jaggi AS. Implications and mechanism of action of gabapentin in neuropathic pain. Arch Pharm Res 2013; 36:237-51. [PMID: 23435945 DOI: 10.1007/s12272-013-0057-y] [Citation(s) in RCA: 174] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 12/14/2012] [Indexed: 01/25/2023]
Abstract
Gabapentin is an anti-epileptic agent but now it is also recommended as first line agent in neuropathic pain, particularly in diabetic neuropathy and post herpetic neuralgia. α2δ-1, an auxillary subunit of voltage gated calcium channels, has been documented as its main target and its specific binding to this subunit is described to produce different actions responsible for pain attenuation. The binding to α2δ-1 subunits inhibits nerve injury-induced trafficking of α1 pore forming units of calcium channels (particularly N-type) from cytoplasm to plasma membrane (membrane trafficking) of pre-synaptic terminals of dorsal root ganglion (DRG) neurons and dorsal horn neurons. Furthermore, the axoplasmic transport of α2δ-1 subunits from DRG to dorsal horns neurons in the form of anterograde trafficking is also inhibited in response to gabapentin administration. Gabapentin has also been shown to induce modulate other targets including transient receptor potential channels, NMDA receptors, protein kinase C and inflammatory cytokines. It may also act on supra-spinal region to stimulate noradrenaline mediated descending inhibition, which contributes to its anti-hypersensitivity action in neuropathic pain.
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Affiliation(s)
- Ankesh Kukkar
- Department of Pharmaceutical Sciences and Drug Research, Punjabi University, Patiala, 147002, Punjab, India
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61
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Abstract
BACKGROUND It is estimated that at least 200 000 cases of brain metastases occur each year in the US, which is 10 times the number of patients diagnosed with primary brain tumors. Brain metastasis is associated with poor prognosis, neurological deterioration, diminished quality of life, and extremely short survival. Favorable interactions between tumor cells and cerebral microvascular endothelial cells encourage tumor growth in the central nervous system, while tumor cell interactions with astrocytes protect brain metastases from the cytotoxic effects of chemotherapy. CONTENT We review the pathogenesis of brain metastasis and emphasize the contributions of microvascular endothelial cells and astrocytes to disease progression and therapeutic resistance. Animal models used to study brain metastasis are also discussed. SUMMARY Brain metastasis has many unmet clinical needs. There are few clinically relevant tumor models and no targeted therapies specific for brain metastases, and the mean survival for untreated patients is 5 weeks. Improved clinical outcomes are dependent on an enhanced understanding of the metastasis-initiating population of cells and the identification of microenvironmental factors that encourage disease progression in the central nervous system.
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Affiliation(s)
- Robert R Langley
- Department of Cancer Biology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
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62
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Abstract
Astrocytes exhibit their excitability based on variations in cytosolic Ca(2+) levels, which leads to variety of signalling events. Only recently, however, intracellular fluctuations of more abundant cation Na(+) are brought in the limelight of glial signalling. Indeed, astrocytes possess several plasmalemmal molecular entities that allow rapid transport of Na(+) across the plasma membrane: (1) ionotropic receptors, (2) canonical transient receptor potential cation channels, (3) neurotransmitter transporters and (4) sodium-calcium exchanger. Concerted action of these molecules in controlling cytosolic Na(+) may complement Ca(2+) signalling to provide basis for complex bidirectional astrocyte-neurone communication at the tripartite synapse.
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Mathews DC, Henter ID, Zarate CA. Targeting the glutamatergic system to treat major depressive disorder: rationale and progress to date. Drugs 2012; 72:1313-33. [PMID: 22731961 DOI: 10.2165/11633130-000000000-00000] [Citation(s) in RCA: 154] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Major depressive disorder (MDD) is a severe, debilitating medical illness that affects millions of individuals worldwide. The young age of onset and chronicity of the disorder has a significant impact on the long-term disability that affected individuals face. Most existing treatments have focused on the 'monoamine hypothesis' for rational design of compounds. However, patients continue to experience low remission rates, residual subsyndromal symptoms, relapses and overall functional impairment. In this context, growing evidence suggests that the glutamatergic system is uniquely central to the neurobiology and treatment of MDD. Here, we review data supporting the involvement of the glutamatergic system in the pathophysiology of MDD, and discuss the efficacy of glutamatergic agents as novel therapeutics. Preliminary clinical evidence has been promising, particularly with regard to the N-methyl-D-aspartate (NMDA) antagonist ketamine as a 'proof-of-concept' agent. The review also highlights potential molecular and inflammatory mechanisms that may contribute to the rapid antidepressant response seen with ketamine. Because existing pharmacological treatments for MDD are often insufficient for many patients, the next generation of treatments needs to be more effective, rapid acting and better tolerated than currently available medications. There is extant evidence that the glutamatergic system holds considerable promise for developing the next generation of novel and mechanistically distinct agents for the treatment of MDD.
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Affiliation(s)
- Daniel C Mathews
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
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64
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Marcello L, Cavaliere C, Colangelo A, Bianco M, Cirillo G, Alberghina L, Papa M. Remodelling of supraspinal neuroglial network in neuropathic pain is featured by a reactive gliosis of the nociceptive amygdala. Eur J Pain 2012. [DOI: 10.1002/j.1532-2149.2012.00255.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- L. Marcello
- Laboratory of Morphology of Neural Networks; Department of Medicina Pubblica Clinica e Preventiva; Second University of Napoli; Italy
| | - C. Cavaliere
- Laboratory of Morphology of Neural Networks; Department of Medicina Pubblica Clinica e Preventiva; Second University of Napoli; Italy
| | | | - M.R. Bianco
- Laboratory of Morphology of Neural Networks; Department of Medicina Pubblica Clinica e Preventiva; Second University of Napoli; Italy
| | - G. Cirillo
- Laboratory of Morphology of Neural Networks; Department of Medicina Pubblica Clinica e Preventiva; Second University of Napoli; Italy
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Dias AM. The Integration of the Glutamatergic and the White Matter Hypotheses of Schizophrenia's Etiology. Curr Neuropharmacol 2012; 10:2-11. [PMID: 22942875 PMCID: PMC3286845 DOI: 10.2174/157015912799362742] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Revised: 05/27/2011] [Accepted: 06/24/2011] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND schizophrenia's endophenotipic profile is not only generally complex, but often varies from case to case. The perspective of trying to define specific anatomic correlates of the syndrome has led to disappointing results. In that context, neurophysiologic hypotheses (e.g. glutamatergic hypothesis) and connectivity hypotheses became prominent. Nevertheless, despite their commitment to the principle of denying 'localist' views and approaching the syndrome's endophenotype from a whole brain perspective, efforts to integrate both have not flourished at this moment in time. OBJECTIVES This paper aims to introduce a new etiological model that integrates the glutamatergic and the WM (WM) hypotheses of schizophrenia's etiology. This model proposes to serve as a framework in order to relate to patterns of brain abnormalities from the onset of the syndrome to stages of advanced chronification. HIGHLIGHTS Neurotransmitter abnormalities forego noticeable WM abnormalities. The former, chiefly represented by NMDAR hypo-function and associated molecular cascades, is related to the first signs of cell loss. This process is both directly and indirectly integrated to the underpinning of WM structural abnormalities; not only is the excess of glutamate toxic to the WM, but its disruption is associated to the expression of known genetic risk factors (e.g., NRG-1). A second level of the model develops the idea that abnormal neurotransmission within specific neural populations ('motifs') impair particular cognitive abilities, while subsequent WM structural abnormalities impair the integration of brain functions and multimodality. As a result of this two-stage dynamic, the affected individual progresses from experiencing specific cognitive and psychological deficits, to a condition of cognitive and existential fragmentation, linked to hardly reversible decreases in psychosocial functioning.
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66
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Mathews DC, Henter ID, Zarate CA. Targeting the glutamatergic system to treat major depressive disorder: rationale and progress to date. Drugs 2012. [PMID: 22731961 DOI: 10.2165/11633130‐000000000‐00000] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Major depressive disorder (MDD) is a severe, debilitating medical illness that affects millions of individuals worldwide. The young age of onset and chronicity of the disorder has a significant impact on the long-term disability that affected individuals face. Most existing treatments have focused on the 'monoamine hypothesis' for rational design of compounds. However, patients continue to experience low remission rates, residual subsyndromal symptoms, relapses and overall functional impairment. In this context, growing evidence suggests that the glutamatergic system is uniquely central to the neurobiology and treatment of MDD. Here, we review data supporting the involvement of the glutamatergic system in the pathophysiology of MDD, and discuss the efficacy of glutamatergic agents as novel therapeutics. Preliminary clinical evidence has been promising, particularly with regard to the N-methyl-D-aspartate (NMDA) antagonist ketamine as a 'proof-of-concept' agent. The review also highlights potential molecular and inflammatory mechanisms that may contribute to the rapid antidepressant response seen with ketamine. Because existing pharmacological treatments for MDD are often insufficient for many patients, the next generation of treatments needs to be more effective, rapid acting and better tolerated than currently available medications. There is extant evidence that the glutamatergic system holds considerable promise for developing the next generation of novel and mechanistically distinct agents for the treatment of MDD.
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Affiliation(s)
- Daniel C Mathews
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
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67
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Saab AS, Neumeyer A, Jahn HM, Cupido A, Šimek AAM, Boele HJ, Scheller A, Le Meur K, Götz M, Monyer H, Sprengel R, Rubio ME, Deitmer JW, De Zeeuw CI, Kirchhoff F. Bergmann glial AMPA receptors are required for fine motor coordination. Science 2012; 337:749-53. [PMID: 22767895 DOI: 10.1126/science.1221140] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The impact of glial neurotransmitter receptors in vivo is still elusive. In the cerebellum, Bergmann glial (BG) cells express α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors (AMPARs) composed exclusively of GluA1 and/or GluA4 subunits. With the use of conditional gene inactivation, we found that the majority of cerebellar GluA1/A4-type AMPARs are expressed in BG cells. In young mice, deletion of BG AMPARs resulted in retraction of glial appendages from Purkinje cell (PC) synapses, increased amplitude and duration of evoked PC currents, and a delayed formation of glutamatergic synapses. In adult mice, AMPAR inactivation also caused retraction of glial processes. The physiological and structural changes were accompanied by behavioral impairments in fine motor coordination. Thus, BG AMPARs are essential to optimize synaptic integration and cerebellar output function throughout life.
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Affiliation(s)
- Aiman S Saab
- Department of Molecular Physiology, University of Saarland, Homburg, Germany
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68
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Chang PKY, Verbich D, McKinney RA. AMPA receptors as drug targets in neurological disease - advantages, caveats, and future outlook. Eur J Neurosci 2012; 35:1908-16. [DOI: 10.1111/j.1460-9568.2012.08165.x] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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69
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Berger J, Dumont A, Focant M, Vergouts M, Sternotte A, Calas AG, Goursaud S, Hermans E. Opposite regulation of metabotropic glutamate receptor 3 and metabotropic glutamate receptor 5 by inflammatory stimuli in cultured microglia and astrocytes. Neuroscience 2012; 205:29-38. [DOI: 10.1016/j.neuroscience.2011.12.044] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Revised: 12/13/2011] [Accepted: 12/23/2011] [Indexed: 01/09/2023]
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70
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The vulnerability of nitrergic neurons to transient spinal cord ischemia: a quantitative immunohistochemical and histochemical study. J Mol Histol 2012; 43:203-13. [DOI: 10.1007/s10735-011-9386-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Accepted: 12/17/2011] [Indexed: 12/21/2022]
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71
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Yoshizumi M, Eisenach JC, Hayashida KI. Riluzole and gabapentinoids activate glutamate transporters to facilitate glutamate-induced glutamate release from cultured astrocytes. Eur J Pharmacol 2011; 677:87-92. [PMID: 22206816 DOI: 10.1016/j.ejphar.2011.12.015] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Revised: 11/29/2011] [Accepted: 12/07/2011] [Indexed: 02/07/2023]
Abstract
We have recently demonstrated that the glutamate transporter activator riluzole paradoxically enhanced glutamate-induced glutamate release from cultured astrocytes. We further showed that both riluzole and the α(2)δ subunit ligand gabapentin activated descending inhibition in rats by increasing glutamate receptor signaling in the locus coeruleus and hypothesized that these drugs share common mechanisms to enhance glutamate release from astrocytes. In the present study, we examined the effects of riluzole and gabapentin on glutamate uptake and release and glutamate-induced Ca(2+) responses in primary cultures of astrocytes. Riluzole and gabapentin facilitated glutamate-induced glutamate release from astrocytes and significantly increased glutamate uptake, the latter being completely blocked by the non-selective glutamate transporter blocker DL-threo-β-benzyloxyaspartic acid (DL-TBOA). Riluzole and gabapentin also enhanced the glutamate-induced increase in intracellular Ca(2+) concentrations. Some α(2)δ subunit ligands, pregabalin and L-isoleucine, enhanced the glutamate-induced Ca(2+) response, whereas another, 3-exo-aminobicyclo[2.2.1]heptane-2-exo-carboxylic acid (ABHCA), did not. The enhancement of glutamate-induced intracellular Ca(2+) response by riluzole and gabapentin was blocked by the DL-TBOA and an inhibitor of Na(+)/Ca(2+) exchange, 2-[2-[4-(4-nitrobenzyloxy)phenyl]ethyl]isothiurea (KB-R7943). Gabapentin's enhancement of Ca(2+) increase was specific to glutamate stimulation, as it was not mimicked with stimulation by ATP. These results suggest that riluzole and gabapentin enhance Na(+)-glutamate co-transport through glutamate transporters, induce subsequent Ca(2+) influx via the reverse mode of Na(+)/Ca(2+) exchange, and thereby facilitate Ca(2+)-dependent glutamate release by glutamate in astrocytes. The present study also demonstrates a novel target of gabapentinoid action in astrocytes other than α(2)δ subunits in neurons.
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Affiliation(s)
- Masaru Yoshizumi
- Department of Anesthesiology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA
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72
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Illes P, Verkhratsky A, Burnstock G, Franke H. P2X receptors and their roles in astroglia in the central and peripheral nervous system. Neuroscientist 2011; 18:422-38. [PMID: 22013151 DOI: 10.1177/1073858411418524] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Astrocytes are a class of neural cells that control homeostasis at all levels of the central and peripheral nervous system. There is a bidirectional neuron-glia interaction via a number of extracellular signaling molecules, glutamate and ATP being the most widespread. ATP activates ionotropic P2X and metabotropic P2Y receptors, which operate in both neurons and astrocytes. Morphological, biochemical, and functional evidence indicates the expression of astroglial P2X(1/5) heteromeric and P2X(7) homomeric receptors, which mediate physiological and pathophysiological responses. Activation of P2X(1/5) receptors triggers rapid increase of intracellular Na(+) that initiates immediate cellular reactions, such as the depression of the glutamate transporter to keep high glutamate concentrations in the synaptic cleft, the activation of the local lactate shuttle to supply energy substrate to pre- and postsynaptic neuronal structures, and the reversal of the Na(+)/Ca(2+) exchange resulting in additional Ca(2+) entry. The consequences of P2X(7) receptor activation are mostly but not exclusively mediated by the entry of Ca(2+) and result in reorganization of the cytoskeleton, inflammation, apoptosis/necrosis, and proliferation, usually at a prolonged time scale. Thus, astroglia detect by P2X(1/5) and P2X(7) receptors both physiological concentrations of ATP secreted from presynaptic nerve terminals and also much higher concentrations of ATP attained under pathological conditions.
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Affiliation(s)
- Peter Illes
- Rudolf-Boehm-Institute of Pharmacology and Toxicology, University of Leipzig, Germany.
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73
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Rusakov DA, Zheng K, Henneberger C. Astrocytes as regulators of synaptic function: a quest for the Ca2+ master key. Neuroscientist 2011; 17:513-23. [PMID: 21536839 PMCID: PMC3374854 DOI: 10.1177/1073858410387304] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The emerging role of astrocytes in neural communication represents a conceptual challenge. In striking contrast to the rapid and highly space- and time-constrained machinery of neuronal spike propagation and synaptic release, astroglia appear slow and imprecise. Although a large body of independent experiments documents active signal exchange between astrocytes and neurons, some genetic models have raised doubts about the major Ca2+ -dependent molecular mechanism routinely associated with release of "gliotransmitters." A limited understanding of astrocytic Ca2+ signaling and the imperfect compatibility between physiology and experimental manipulations seem to have contributed to this conceptual bottleneck. Experimental approaches providing mechanistic insights into the diverse mechanisms of intra-astrocyte Ca2+ signaling on the nanoscale are needed to understand Ca2+ -dependent astrocytic function in vivo. This review highlights limitations and potential advantages of such approaches from the current methodological perspective.
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Affiliation(s)
- Dmitri A Rusakov
- UCL Institute of Neurology, University College London, London, UK.
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74
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López-Bayghen E, Ortega A. Glial glutamate transporters: New actors in brain signaling. IUBMB Life 2011; 63:816-23. [DOI: 10.1002/iub.536] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 06/10/2011] [Indexed: 01/10/2023]
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75
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Wu W, Li M, Liu L, Gao J, Kong H, Ding J, Hu G, Xiao M. Astrocyte activation but not neuronal impairment occurs in the hippocampus of mice after 2weeks of d-galactose exposure. Life Sci 2011; 89:355-63. [DOI: 10.1016/j.lfs.2011.06.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Revised: 06/19/2011] [Accepted: 06/27/2011] [Indexed: 12/18/2022]
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76
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Astrocytes upregulate survival genes in tumor cells and induce protection from chemotherapy. Neoplasia 2011; 13:286-98. [PMID: 21390191 DOI: 10.1593/neo.11112] [Citation(s) in RCA: 190] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Revised: 01/24/2011] [Accepted: 01/27/2011] [Indexed: 11/18/2022] Open
Abstract
In the United States, more than 40% of cancer patients develop brain metastasis. The median survival for untreated patients is 1 to 2 months, which may be extended to 6 months with conventional radiotherapy and chemotherapy. The growth and survival of metastasis depend on the interaction of tumor cells with host factors in the organ microenvironment. Brain metastases are surrounded and infiltrated by activated astrocytes and are highly resistant to chemotherapy. We report here that coculture of human breast cancer cells or lung cancer cells with murine astrocytes (but not murine fibroblasts) led to the up-regulation of survival genes, including GSTA5, BCL2L1, and TWIST1, in the tumor cells. The degree of up-regulation directly correlated with increased resistance to all tested chemotherapeutic agents. We further show that the up-regulation of the survival genes and consequent resistance are dependent on the direct contact between the astrocytes and tumor cells through gap junctions and are therefore transient. Knocking down these genes with specific small interfering RNA rendered the tumor cells sensitive to chemotherapeutic agents. These data clearly demonstrate that host cells in the microenvironment influence the biologic behavior of tumor cells and reinforce the contention that the organ microenvironment must be taken into consideration during the design of therapy.
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77
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Domingues AMDJ, Neugebauer KM, Fern R. Identification of four functional NR3B isoforms in developing white matter reveals unexpected diversity among glutamate receptors. J Neurochem 2011; 117:449-60. [PMID: 21320125 DOI: 10.1111/j.1471-4159.2011.07212.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Functional neurotransmitter receptors are expressed in central white matter, where they mediate ischemic damage to glia and may be involved in cell-cell signalling. In this study, we analysed NMDA receptor NR1, NR2B-C and NR3A-B subunit expression in the brain and optic nerve by molecular cloning. In addition to the canonical forms of NR1 and NR2, four previously unknown NR3B variants, generated by alternative splicing, were identified. The variants encoded for isoforms with deletions of 8/15 amino acids in the N-terminal domain or 200/375 amino acids removing one or three transmembrane domains and part of the C-terminal domain, as compared with the previously characterized NR3B isoform. Co-expression of NR3B isoforms with NR1/NR2A-C modulated the amplitude and Mg(2+)-sensitivity of glutamate responses in a NR2 subunit-dependent fashion, with significant variations in the effects produced by different isoforms. These effects were not the result of reduced surface expression of the receptor complex since all NR3B isoforms reduced surface expression by a similar degree. These data reveal previously uncharacterized regulation of NMDA receptor function by alternative splicing of the NR3B subunit.
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78
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Cifra A, Nani F, Nistri A. Riluzole is a potent drug to protect neonatal rat hypoglossal motoneurons in vitro from excitotoxicity due to glutamate uptake block. Eur J Neurosci 2011; 33:899-913. [PMID: 21324003 DOI: 10.1111/j.1460-9568.2010.07579.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Excitotoxic damage to motoneurons is thought to be an important contribution to the pathogenesis of amyotrophic lateral sclerosis (ALS), a slowly developing degeneration of motoneurons that, in most cases of sporadic occurrence, is associated with impaired glial glutamate uptake. Riluzole is the only drug licensed for symptomatic ALS treatment and is proposed to delay disease progression. As riluzole is administered only after full ALS manifestation, it is unclear if its early use might actually prevent motoneuron damage. We explored this issue by using, as a simple in vitro model, hypoglossal motoneurons (a primary target of ALS) of the neonatal rat brainstem slice preparation exposed to excitotoxic stress due to glutamate uptake block by DL-threo-β-benzyloxyaspartate (TBOA). TBOA evoked sustained network bursting, early (1 h) enhancement of the S100B immunostaining of gray matter astrocytes, and activated the motoneuronal stress ATF-3 transcription factor; 4 h later, loss (30%) of motoneuron staining ensued and pyknosis appeared. Riluzole (5 μM; applied 15 min after TBOA) inhibited bursting, decreased the frequency of spontaneous glutamatergic events, reversed changes in S100B immunostaining and prevented late loss of motoneuron staining. These results show that excitotoxicity induced by glutamate uptake block developed slowly, and was sensed by glia and motoneurons with delayed cell death. Our data provide novel evidence for the neuroprotective action of riluzole on motoneurons and glia when applied early after an excitotoxic stimulus.
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Affiliation(s)
- Alessandra Cifra
- Neurobiology Sector, International School for Advanced Studies (SISSA), Via Bonomea 265, 34136 Trieste, Italy
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79
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Pelligrino DA, Vetri F, Xu HL. Purinergic mechanisms in gliovascular coupling. Semin Cell Dev Biol 2011; 22:229-36. [PMID: 21329762 DOI: 10.1016/j.semcdb.2011.02.010] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 01/11/2011] [Accepted: 02/07/2011] [Indexed: 01/23/2023]
Abstract
Regional elevations in cerebral blood flow (CBF) often occur in response to localized increases in cerebral neuronal activity. An ever expanding literature has linked this neurovascular coupling process to specific signaling pathways involving neuronal synapses, astrocytes and cerebral arteries and arterioles. Collectively, these structures are termed the "neurovascular unit" (NVU). Astrocytes are thought to be the cornerstone of the NVU. Thus, not only do astrocytes "detect" increased synaptic activity, they can transmit that information to proximal and remote astrocytic sites often through a Ca(2+)- and ATP-related signaling process. At the vascular end of the NVU, a Ca(2+)-dependent formation and release of vasodilators, or substances linked to vasodilation, can occur. The latter category includes ATP, which upon its appearance in the extracellular compartment, can be rapidly converted to the potent vasodilator, adenosine, via the action of ecto-nucleotidases. In the present review, we give consideration to experimental model-specific variations in purinergic influences on gliovascular signaling mechanisms, focusing on the cerebral cortex. In that discussion, we compare findings obtained using in vitro (rodent brain slice) models and multiple in vivo models (2-photon imaging; somatosensory stimulation-evoked cortical hyperemia; and sciatic nerve stimulation-evoked pial arteriolar dilation). Additional attention is given to the importance of upstream (remote) vasodilation; the key role played by extracellular ATP hydrolysis (via ecto-nucleotidases) in gliovascular coupling; and interactions among multiple signaling pathways.
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Affiliation(s)
- Dale A Pelligrino
- Neuroanesthesia Research Laboratory, University of Illinois at Chicago, Chicago, IL 60612, USA.
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80
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Bradley SJ, Langmead CJ, Watson JM, Challiss RAJ. Quantitative analysis reveals multiple mechanisms of allosteric modulation of the mGlu5 receptor in rat astroglia. Mol Pharmacol 2011; 79:874-85. [PMID: 21321061 DOI: 10.1124/mol.110.068882] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Positive and negative allosteric modulators (PAMs and NAMs, respectively) of the type 5 metabotropic glutamate (mGlu5) receptor have demonstrable therapeutic potential in an array of neurological and psychiatric disorders. Here, we have used rat cortical astrocytes to investigate how PAMs and NAMs mediate their activity and reveal marked differences between PAMs with respect to their modulation of orthosteric agonist affinity and efficacy. Affinity cooperativity factors (α) were assessed using [(3)H]2-methyl-6-(phenylethynyl)-pyridine (MPEP)-PAM competition binding in the absence and presence of orthosteric agonist, whereas efficacy cooperativity factors (β) were calculated from net affinity/efficacy cooperativity parameters (αβ) obtained from analyses of the abilities of PAMs to potentiate [(3)H]inositol phosphate accumulation in astrocytes stimulated with a submaximal (EC(20)) concentration of orthosteric agonist. We report that whereas 3,3'-difluorobenzaldazine (DFB) and 3-cyano-N-(1,3-diphenyl-1H-prazol-5-yl)benzamide (CDPPB) primarily exert their allosteric modulatory effects through modifying the apparent orthosteric agonist affinity at the astrocyte mGlu5 receptor, the effects of S-(4-fluoro-phenyl)-{3-[3-(4-fluoro-phenyl)-[1,2,4]oxadiazol-5-yl]-piperidinl-1-yl}-methanone (ADX47273) are mediated primarily via efficacy-driven modulation. In [(3)H]MPEP-NAM competition binding assays, both MPEP and 2-(2-(3-methoxyphenyl)ethynyl)-5-methylpyridine (M-5MPEP) defined similar specific binding components, with affinities that were unaltered in the presence of orthosteric agonist, indicating wholly negative efficacy-driven modulations. It is noteworthy that whereas M-5MPEP only partially inhibited orthosteric agonist-stimulated [(3)H]inositol phosphate accumulation in astrocytes, it could completely suppress Ca(2+) oscillations stimulated by quisqualate or (S)-3,5-dihydroxyphenylglycine. In contrast, MPEP was fully inhibitory with respect to both functional responses. The finding that M-5MPEP has different functional effects depending on the endpoint measured is discussed as a possible example of permissive allosteric antagonism.
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Affiliation(s)
- Sophie J Bradley
- Department of Cell Physiology and Pharmacology, University of Leicester, Leicester, United Kingdom
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81
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Palygin O, Lalo U, Verkhratsky A, Pankratov Y. Ionotropic NMDA and P2X1/5 receptors mediate synaptically induced Ca2+ signalling in cortical astrocytes. Cell Calcium 2011; 48:225-31. [PMID: 20926134 DOI: 10.1016/j.ceca.2010.09.004] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 09/05/2010] [Accepted: 09/07/2010] [Indexed: 10/19/2022]
Abstract
Local, global and propagating calcium (Ca(2+)) signals provide the substrate for glial excitability. Here we analyse Ca(2+) permeability of NMDA and P2X(1/5) receptors expressed in cortical astrocytes and provide evidence that activation of these receptors trigger astroglial Ca(2+) signals when stimulated by either endogenous agonists or by synaptic release of neurotransmitters. The Ca(2+) permeability of the ionotropic receptors was determined by reversal potential shift analysis; the permeability ratio P(Ca)/P(K) was 3.1 for NMDA receptors and 2.2 for P2X(1/5) receptors. Selective stimulation of ionotropic receptors (with NMDA and α,β-methyleneATP) in freshly isolated cortical astrocytes induced ion currents associated with transient increases in cytosolic Ca(2+) concentration ([Ca(2+)](i)). Stimulation of neuronal afferents in cortical slices triggered glial synaptic currents and [Ca(2+)](i) responses, which were partially blocked by selective antagonists of NMDA (D-AP5 and UBP141) and P2X(1/5) (NF449) receptors. We conclude that ionotropic receptors contribute to astroglial Ca(2+) signalling and may provide a specific mechanism for fast neuronal-glial signalling at the synaptic level.
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Affiliation(s)
- Oleg Palygin
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK
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82
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Dityatev A, Rusakov DA. Molecular signals of plasticity at the tetrapartite synapse. Curr Opin Neurobiol 2011; 21:353-9. [PMID: 21277196 DOI: 10.1016/j.conb.2010.12.006] [Citation(s) in RCA: 180] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 12/24/2010] [Accepted: 12/27/2010] [Indexed: 01/19/2023]
Abstract
The emergence of astroglia as an important participant of the synaptic machinery has led to the 'tripartite synapse' hypothesis. Recent findings suggest that synaptic signaling also involves the surrounding extracellular matrix (ECM). The ECM can incorporate and store molecular traces of both neuronal and glial activities. It can also modulate function of local receptors or ion channels and send diffuse molecular signals using products of its use-dependent proteolytic cleavage. Recent experimental findings implicate the ECM in mechanisms of synaptic plasticity and glial remodeling, thus lending support to the 'tetrapartite synapse' concept. This inclusive view might help to understand better the mechanisms underlying signal integration and novel forms of long-term homeostatic regulation in the brain.
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Affiliation(s)
- Alexander Dityatev
- Department of Neuroscience and Brain Technologies, Italian Institute of Technology, via Morego 30, Genova 16163, Italy.
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83
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Chen HH, Lin SC, Chan MH. Protective and Restorative Effects of Magnolol on Neurotoxicity in Mice with 6-Hydroxydopamine-Induced Hemiparkinsonism. NEURODEGENER DIS 2011; 8:364-74. [DOI: 10.1159/000323872] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Accepted: 12/27/2010] [Indexed: 11/19/2022] Open
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84
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Verkhratsky A. Physiology of neuronal–glial networking. Neurochem Int 2010; 57:332-43. [DOI: 10.1016/j.neuint.2010.02.002] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Revised: 01/05/2010] [Accepted: 02/01/2010] [Indexed: 10/19/2022]
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85
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Verkhratsky A, Olabarria M, Noristani HN, Yeh CY, Rodriguez JJ. Astrocytes in Alzheimer's disease. Neurotherapeutics 2010; 7:399-412. [PMID: 20880504 PMCID: PMC5084302 DOI: 10.1016/j.nurt.2010.05.017] [Citation(s) in RCA: 317] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Revised: 04/25/2010] [Accepted: 05/10/2010] [Indexed: 11/24/2022] Open
Abstract
The circuitry of the human brain is formed by neuronal networks embedded into astroglial syncytia. The astrocytes perform numerous functions, providing for the overall brain homeostasis, assisting in neurogenesis, determining the micro-architecture of the grey matter, and defending the brain through evolutionary conserved astrogliosis programs. Astroglial cells are engaged in neurological diseases by determining the progression and outcome of neuropathological process. Astrocytes are specifically involved in various neurodegenerative diseases, including Alzheimer's disease, amyotrophic lateral sclerosis, Parkinson's disease, and various forms of dementia. Recent evidence suggest that early stages of neurodegenerative processes are associated with atrophy of astroglia, which causes disruptions in synaptic connectivity, disbalance in neurotransmitter homeostasis, and neuronal death through increased excitotoxicity. At the later stages, astrocytes become activated and contribute to the neuroinflammatory component of neurodegeneration.
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Affiliation(s)
- Alexei Verkhratsky
- grid.5379.80000000121662407Faculty of Life Sciences, The University of Manchester, M13 9PT Manchester, UK
- grid.11480.3c0000000121671098Ikerbasque, Basque Foundation for Science, Department of Neuroscience, The University of the Basque Country UPV/EHU, Technological Park, Bldg. 205, Floor-1, Laida Bidea, 48170 Zamudio, Vizcaya Spain
| | - Markel Olabarria
- grid.5379.80000000121662407Faculty of Life Sciences, The University of Manchester, M13 9PT Manchester, UK
| | - Harun N. Noristani
- grid.5379.80000000121662407Faculty of Life Sciences, The University of Manchester, M13 9PT Manchester, UK
| | - Chia-Yu Yeh
- grid.5379.80000000121662407Faculty of Life Sciences, The University of Manchester, M13 9PT Manchester, UK
| | - Jose Julio Rodriguez
- grid.418095.10000000110153316Institute of Experimental Medicine, ASCR, 142 20 Prague, Czech Republic
- grid.424810.b0000000404672314Ikerbasque, Basque Foundation for Science, 48011 Bilbao, Spain
- grid.11480.3c0000000121671098Department of Neurosciences, University of the Basque Country UPV/EHU, 48940 Leioa, Spain
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86
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Ionotropic receptors in neuronal-astroglial signalling: what is the role of "excitable" molecules in non-excitable cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:992-1002. [PMID: 20869992 DOI: 10.1016/j.bbamcr.2010.09.007] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2010] [Revised: 09/13/2010] [Accepted: 09/16/2010] [Indexed: 01/02/2023]
Abstract
Astroglial cells were long considered to serve merely as the structural and metabolic supporting cast and scenery against which the shining neurones perform their illustrious duties. Relatively recent evidence, however, indicates that astrocytes are intimately involved in many of the brain's functions. Astrocytes possess a diverse assortment of ionotropic transmitter receptors, which enable these glial cells to respond to many of the same signals that act on neurones. Ionotropic receptors mediate neurone-driven signals to astroglial cells in various brain areas including neocortex, hippocampus and cerebellum. Activation of ionotropic receptors trigger rapid signalling events in astroglia; these events, represented by local Ca(2+) or Na(+) signals provide the mechanism for fast neuronal-glial signalling at the synaptic level. Since astrocytes can detect chemical transmitters that are released from neurones and can release their own extracellular signals, gliotransmitters, they are intricately involved in homocellular and heterocellular signalling mechanisms in the nervous system. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.
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87
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Kuzhandaivel A, Margaryan G, Nistri A, Mladinic M. Extensive glial apoptosis develops early after hypoxic-dysmetabolic insult to the neonatal rat spinal cord in vitro. Neuroscience 2010; 169:325-38. [DOI: 10.1016/j.neuroscience.2010.05.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Revised: 05/03/2010] [Accepted: 05/05/2010] [Indexed: 01/08/2023]
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88
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Liu L, Su Y, Yang W, Xiao M, Gao J, Hu G. Disruption of neuronal-glial-vascular units in the hippocampus of ovariectomized mice injected with d-galactose. Neuroscience 2010; 169:596-608. [DOI: 10.1016/j.neuroscience.2010.05.028] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Revised: 05/11/2010] [Accepted: 05/14/2010] [Indexed: 12/23/2022]
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89
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Verkhratsky A, Parpura V, Rodríguez JJ. Where the thoughts dwell: the physiology of neuronal-glial "diffuse neural net". ACTA ACUST UNITED AC 2010; 66:133-51. [PMID: 20546785 DOI: 10.1016/j.brainresrev.2010.05.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Revised: 05/11/2010] [Accepted: 05/17/2010] [Indexed: 02/07/2023]
Abstract
The mechanisms underlying the production of thoughts by exceedingly complex cellular networks that construct the human brain constitute the most challenging problem of natural sciences. Our understanding of the brain function is very much shaped by the neuronal doctrine that assumes that neuronal networks represent the only substrate for cognition. These neuronal networks however are embedded into much larger and probably more complex network formed by neuroglia. The latter, although being electrically silent, employ many different mechanisms for intercellular signalling. It appears that astrocytes can control synaptic networks and in such a capacity they may represent an integral component of the computational power of the brain rather than being just brain "connective tissue". The fundamental question of whether neuroglia is involved in cognition and information processing remains, however, open. Indeed, a remarkable increase in the number of glial cells that distinguishes the human brain can be simply a result of exceedingly high specialisation of the neuronal networks, which delegated all matters of survival and maintenance to the neuroglia. At the same time potential power of analogue processing offered by internally connected glial networks may represent the alternative mechanism involved in cognition.
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90
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Shoji Y, Yamaguchi-Yamada M, Yamamoto Y. Glutamate- and GABA-mediated neuron–satellite cell interaction in nodose ganglia as revealed by intracellular calcium imaging. Histochem Cell Biol 2010; 134:13-22. [DOI: 10.1007/s00418-010-0711-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/14/2010] [Indexed: 12/19/2022]
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91
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Hayashida KI, Parker RA, Eisenach JC. Activation of glutamate transporters in the locus coeruleus paradoxically activates descending inhibition in rats. Brain Res 2010; 1317:80-6. [PMID: 20059984 DOI: 10.1016/j.brainres.2009.12.086] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Revised: 12/15/2009] [Accepted: 12/29/2009] [Indexed: 02/01/2023]
Abstract
Descending noradrenergic inhibition is an important endogenous pain-relief mechanism which can be activated by local glutamate signaling. In the present study, we examined the effect of glutamate transporter activation by riluzole in the regulation of activity of locus coeruleus (LC) neurons, which provide the major inhibitory descending noradrenergic projection to the spinal cord. Local injection of riluzole into the LC dose-dependently reduced hypersensitivity in rats after L5-L6 spinal nerve ligation (SNL). This anti-hypersensitivity effect of LC-injected riluzole was blocked by intrathecal administration of the alpha2-adrenoceptor antagonist idazoxan and intra-LC co-injection of the AMPA antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and the gap-junction blockers, carbenoxolone (CBX) and meclofenamic acid (MEC). In brainstem slices from normal rats, riluzole increased phosphorylated cAMP response element binding protein (pCREB) expressing nuclei in dopamine-beta-hydroxylase (DbetaH) containing cells in the LC. This riluzole-induced pCREB activation in LC neurons was also blocked by CNQX and CBX. In the primary astrocyte culture, riluzole enhanced glutamate-induced glutamate release. Contrary to expectations, these results suggest that activation of glutamate transporters in the LC results in increase of extracellular glutamate signaling, possibly via facilitation of glutamate release from astrocytes, and activation of LC neurons to induce descending inhibition, and that this paradoxical action of glutamate transporters in the LC requires gap-junction connections.
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Affiliation(s)
- Ken-ichiro Hayashida
- Department of Anesthesiology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston Salem, NC 27157-1009, USA.
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92
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Increased expression of glutamate transporters in subcortical white matter after transient focal cerebral ischemia. Neurobiol Dis 2010; 37:156-65. [DOI: 10.1016/j.nbd.2009.09.019] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Revised: 09/15/2009] [Accepted: 09/27/2009] [Indexed: 12/28/2022] Open
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93
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Langley RR, Fan D, Guo L, Zhang C, Lin Q, Brantley EC, McCarty JH, Fidler IJ. Generation of an immortalized astrocyte cell line from H-2Kb-tsA58 mice to study the role of astrocytes in brain metastasis. Int J Oncol 2009; 35:665-72. [PMID: 19724901 DOI: 10.3892/ijo_00000378] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Astrocytes play a critical role in maintaining cerebral homeostasis and their dysregulation is thought to contribute to the pathogenesis of several diseases, including brain cancer and metastasis. Similar to the human disease, we found that lung and melanoma metastases in the mouse brain are accompanied by a reactive gliosis. To begin to study the biology of astrocytes and examine how these cells might contribute to metastasis formation and progression in the brain, we generated a conditionally immortal astrocyte cell line from H-2Kb-tsA58 mice. Astrocytes grown in culture expressed glial fibrillary acid protein (GFAP), glutamate receptor 1, and the N-methyl-D-aspartate (NMDA) receptor. Astrocytes also expressed the glial-specific transporters excitatory amino acid transporter 1 (EAAT1) and EAAT2. Astrocytes grown under permissive conditions (33 degrees C) expressed SV40 large T antigen and had a doubling time of 36 h, whereas expression of SV40 large T antigen was negligible in astrocytes grown at 37 degrees C for 72 h, which coincided with a plateau in cell division. In a co-culture assay with human lung adenocarcinoma cells (PC14-PE6), astrocytes activated programs in the tumor cells that signal for cell division and survival. Hence, the immortalized cell line will be useful for studying the role of astrocytes in disease processes in the brain, such as metastasis.
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Affiliation(s)
- Robert R Langley
- Department of Cancer Biology, Unit 173, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
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94
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Heneka MT, Rodríguez JJ, Verkhratsky A. Neuroglia in neurodegeneration. ACTA ACUST UNITED AC 2009; 63:189-211. [PMID: 19944719 DOI: 10.1016/j.brainresrev.2009.11.004] [Citation(s) in RCA: 199] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Revised: 11/18/2009] [Accepted: 11/19/2009] [Indexed: 12/11/2022]
Abstract
Neuroglial cells are fundamental for control of brain homeostasis and they represent the intrinsic brain defence system. All forms in neuropathology therefore inevitably involve glia. The neurodegenerative diseases disrupt connectivity within brain circuits affecting neuronal-neuronal, neuronal-glial and glial-glial contacts. In addition neurodegenerative processes trigger universal and conserved glial reactions represented by astrogliosis and microglial activation. The complex of recently acquired knowledge allows us to regard the neurodegenerative diseases as primarily gliodegenerative processes, in which glial cells determine the progression and outcome of neuropathological process.
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Affiliation(s)
- Michael T Heneka
- Klinische Neurowissenschaften, Klinik und Poliklinik für Neurologie, 53127 Bonn, Germany.
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95
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Zepeda RC, Barrera I, Castelán F, Suárez-Pozos E, Melgarejo Y, González-Mejia E, Hernández-Kelly LC, López-Bayghen E, Aguilera J, Ortega A. Glutamate-dependent phosphorylation of the mammalian target of rapamycin (mTOR) in Bergmann glial cells. Neurochem Int 2009; 55:282-7. [DOI: 10.1016/j.neuint.2009.03.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Revised: 02/25/2009] [Accepted: 03/17/2009] [Indexed: 01/05/2023]
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96
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97
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Constantinou S, Fern R. Conduction block and glial injury induced in developing central white matter by glycine, GABA, noradrenalin, or nicotine, studied in isolated neonatal rat optic nerve. Glia 2009; 57:1168-77. [DOI: 10.1002/glia.20839] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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98
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Abernethy AP. Palliative care pharmacotherapy literature summaries and analyses. J Pain Palliat Care Pharmacother 2009; 23:174-81. [PMID: 19492222 DOI: 10.1080/15360280902901404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Timely and important studies are reviewed and commentaries provided by leading palliative care clinicians. Symptoms, interventions, and treatment-related adverse events addressed in this issue are computerized symptom management; anticholinergic agents in lung disease; neuropathic pain and morphine effectiveness; morphine dosing; inflammatory cytokines and pain; oral ghrelin-mimetics and sarcopenia; and opioid-induced bowel dysfunction.
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Affiliation(s)
- Amy P Abernethy
- Duke University Medical Center, Box 3436, Durham, NC 27710, USA.
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99
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Cruz-Solis I, Zepeda RC, Ortiz S, Aguilera J, López-Bayghen E, Ortega A. Glutamate-dependent transcriptional control in Bergmann glia: Sox10 as a repressor. J Neurochem 2009; 109:899-910. [PMID: 19425178 DOI: 10.1111/j.1471-4159.2009.06017.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
UNLABELLED Glutamate (Glu) is the major excitatory transmitter in the vertebrate brain. Ligand-gated and G protein-coupled Glu receptors present in glial cells are presumably involved in neuronal function. Activation of Bergmann glial Glu receptors triggers a membrane to nuclei signaling cascade that regulates gene expression at the transcriptional and translational levels. Sry-related high-mobility group box (Sox10), a member of the conserved high-mobility group box transcription factor family is expressed in neural crest stem cells and in a subset of neural crest-derived lineages that include glial, but not neuronal cells. To gain insight into the role of Sox10 in Bergmann glial cells, we explored its expression and regulation. We demonstrate herein that Sox10 is expressed in Bergmann glial cells and that its DNA binding activity, mRNA, and protein levels as well as its transcriptional behavior augments upon the activation of metabotropic Glu receptors. Increase in Sox10-DNA complexes and Sox10 mRNA and protein levels were found upon exposure to Glu. Over-expression of Sox10 leads to transcriptional repression in reporter gene assays and in one of its target genes: the chick kainate binding protein gene. These findings add a new perspective into glial glutamatergic signaling and suggest the participation of Sox10 in cerebellar glutamatergic transactions. KEYWORDS Bergmann glial cells, glutamate, metabotropic glutamate receptors, signaling, Sox10, transcriptional control.
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Affiliation(s)
- Irma Cruz-Solis
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado, México
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100
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Clement JP, Randall AD, Brown JT. Metabotropic glutamate receptor 1 activity generates persistent,N-methyl-d-aspartate receptor-dependent depression of hippocampal pyramidal cell excitability. Eur J Neurosci 2009; 29:2347-62. [DOI: 10.1111/j.1460-9568.2009.06780.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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