101
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The Glutamine–Glutamate/GABA Cycle: Function, Regional Differences in Glutamate and GABA Production and Effects of Interference with GABA Metabolism. Neurochem Res 2014; 40:402-9. [DOI: 10.1007/s11064-014-1473-1] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 10/30/2014] [Accepted: 10/31/2014] [Indexed: 10/24/2022]
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102
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Fatty acids in energy metabolism of the central nervous system. BIOMED RESEARCH INTERNATIONAL 2014; 2014:472459. [PMID: 24883315 PMCID: PMC4026875 DOI: 10.1155/2014/472459] [Citation(s) in RCA: 123] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Revised: 03/29/2014] [Accepted: 03/29/2014] [Indexed: 12/13/2022]
Abstract
In this review, we analyze the current hypotheses regarding energy metabolism in the neurons and astroglia. Recently, it was shown that up to 20% of the total brain's energy is provided by mitochondrial oxidation of fatty acids. However, the existing hypotheses consider glucose, or its derivative lactate, as the only main energy substrate for the brain. Astroglia metabolically supports the neurons by providing lactate as a substrate for neuronal mitochondria. In addition, a significant amount of neuromediators, glutamate and GABA, is transported into neurons and also serves as substrates for mitochondria. Thus, neuronal mitochondria may simultaneously oxidize several substrates. Astrocytes have to replenish the pool of neuromediators by synthesis de novo, which requires large amounts of energy. In this review, we made an attempt to reconcile β-oxidation of fatty acids by astrocytic mitochondria with the existing hypothesis on regulation of aerobic glycolysis. We suggest that, under condition of neuronal excitation, both metabolic pathways may exist simultaneously. We provide experimental evidence that isolated neuronal mitochondria may oxidize palmitoyl carnitine in the presence of other mitochondrial substrates. We also suggest that variations in the brain mitochondrial metabolic phenotype may be associated with different mtDNA haplogroups.
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103
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El-Khoury R, Panayotis N, Matagne V, Ghata A, Villard L, Roux JC. GABA and glutamate pathways are spatially and developmentally affected in the brain of Mecp2-deficient mice. PLoS One 2014; 9:e92169. [PMID: 24667344 PMCID: PMC3965407 DOI: 10.1371/journal.pone.0092169] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 02/19/2014] [Indexed: 02/03/2023] Open
Abstract
Proper brain functioning requires a fine-tuning between excitatory and inhibitory neurotransmission, a balance maintained through the regulation and release of glutamate and GABA. Rett syndrome (RTT) is a rare genetic disorder caused by mutations in the methyl-CpG binding protein 2 (MECP2) gene affecting the postnatal brain development. Dysfunctions in the GABAergic and glutamatergic systems have been implicated in the neuropathology of RTT and a disruption of the balance between excitation and inhibition, together with a perturbation of the electrophysiological properties of GABA and glutamate neurons, were reported in the brain of the Mecp2-deficient mouse. However, to date, the extent and the nature of the GABA/glutamate deficit affecting the Mecp2-deficient mouse brain are unclear. In order to better characterize these deficits, we simultaneously analyzed the GABA and glutamate levels in Mecp2-deficient mice at 2 different ages (P35 and P55) and in several brain areas. We used a multilevel approach including the quantification of GABA and glutamate levels, as well as the quantification of the mRNA and protein expression levels of key genes involved in the GABAergic and glutamatergic pathways. Our results show that Mecp2-deficient mice displayed regional- and age-dependent variations in the GABA pathway and, to a lesser extent, in the glutamate pathway. The implication of the GABA pathway in the RTT neuropathology was further confirmed using an in vivo treatment with a GABA reuptake inhibitor that significantly improved the lifespan of Mecp2-deficient mice. Our results confirm that RTT mouse present a deficit in the GABAergic pathway and suggest that GABAergic modulators could be interesting therapeutic agents for this severe neurological disorder.
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Affiliation(s)
- Rita El-Khoury
- Aix Marseille Université, GMGF, Marseille, France
- Inserm, UMR_S 910, Marseille, France
| | - Nicolas Panayotis
- Aix Marseille Université, GMGF, Marseille, France
- Inserm, UMR_S 910, Marseille, France
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
| | - Valérie Matagne
- Aix Marseille Université, GMGF, Marseille, France
- Inserm, UMR_S 910, Marseille, France
| | - Adeline Ghata
- Aix Marseille Université, GMGF, Marseille, France
- Inserm, UMR_S 910, Marseille, France
| | - Laurent Villard
- Aix Marseille Université, GMGF, Marseille, France
- Inserm, UMR_S 910, Marseille, France
| | - Jean-Christophe Roux
- Aix Marseille Université, GMGF, Marseille, France
- Inserm, UMR_S 910, Marseille, France
- * E-mail:
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104
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Schousboe A, Madsen KK, Barker-Haliski ML, White HS. The GABA Synapse as a Target for Antiepileptic Drugs: A Historical Overview Focused on GABA Transporters. Neurochem Res 2014; 39:1980-7. [DOI: 10.1007/s11064-014-1263-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 02/10/2014] [Accepted: 02/12/2014] [Indexed: 01/18/2023]
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105
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Shirazi M, Izadi M, Amin M, Rezvani ME, Roohbakhsh A, Shamsizadeh A. Involvement of central TRPV1 receptors in pentylenetetrazole and amygdala-induced kindling in male rats. Neurol Sci 2014; 35:1235-41. [DOI: 10.1007/s10072-014-1689-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Accepted: 02/13/2014] [Indexed: 01/29/2023]
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106
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Jenstad M, Chaudhry FA. The Amino Acid Transporters of the Glutamate/GABA-Glutamine Cycle and Their Impact on Insulin and Glucagon Secretion. Front Endocrinol (Lausanne) 2013; 4:199. [PMID: 24427154 PMCID: PMC3876026 DOI: 10.3389/fendo.2013.00199] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 12/16/2013] [Indexed: 12/21/2022] Open
Abstract
Intercellular communication is pivotal in optimizing and synchronizing cellular responses to keep homeostasis and to respond adequately to external stimuli. In the central nervous system (CNS), glutamatergic and GABAergic signals are postulated to be dependent on the glutamate/GABA-glutamine cycle for vesicular loading of neurotransmitters, for inactivating the signal and for the replenishment of the neurotransmitters. Islets of Langerhans release the hormones insulin and glucagon, but share similarities with CNS cells in for example transcriptional control of development and differentiation, and chromatin methylation. Interestingly, CNS proteins involved in secretion of the neurotransmitters and emitting their responses as well as the regulation of these processes, are also found in islet cells. Moreover, high levels of glutamate, GABA, and glutamine and their respective vesicular and plasma membrane transporters have been shown in the islet cells and there is emerging support for these amino acids and their transporters playing important roles in the maturation and secretion of insulin and glucagon. In this review, we will discuss the feasibility of recent data in the field in relation to the biophysical properties of the transporters (Slc1, Slc17, Slc32, and Slc38) and physiology of hormone secretion in islets of Langerhans.
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Affiliation(s)
- Monica Jenstad
- Institute for Medical Informatics, Oslo University Hospital, Oslo, Norway
- Centre for Cancer Biomedicine, University of Oslo, Oslo, Norway
- *Correspondence: Monica Jenstad, Institute for Medical Informatics, Oslo University Hospital, Radiumhospitalet, PO Box 4953 Nydalen, Oslo NO-0424, Norway e-mail:
| | - Farrukh Abbas Chaudhry
- Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
- The Biotechnology Centre of Oslo, University of Oslo, Oslo, Norway
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107
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Brehme H, Kirschstein T, Schulz R, Köhling R. In vivo treatment with the casein kinase 2 inhibitor 4,5,6,7-tetrabromotriazole augments the slow afterhyperpolarizing potential and prevents acute epileptiform activity. Epilepsia 2013; 55:175-83. [DOI: 10.1111/epi.12474] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Hannes Brehme
- Oscar Langendorff Institute of Physiology; University of Rostock; Rostock Germany
| | - Timo Kirschstein
- Oscar Langendorff Institute of Physiology; University of Rostock; Rostock Germany
| | - Robert Schulz
- Oscar Langendorff Institute of Physiology; University of Rostock; Rostock Germany
| | - Rüdiger Köhling
- Oscar Langendorff Institute of Physiology; University of Rostock; Rostock Germany
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108
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Nissen-Meyer LSH, Chaudhry FA. Protein Kinase C Phosphorylates the System N Glutamine Transporter SN1 (Slc38a3) and Regulates Its Membrane Trafficking and Degradation. Front Endocrinol (Lausanne) 2013; 4:138. [PMID: 24106489 PMCID: PMC3788335 DOI: 10.3389/fendo.2013.00138] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 09/16/2013] [Indexed: 01/11/2023] Open
Abstract
The system N transporter SN1 (also known as SNAT3) is enriched on perisynaptic astroglial cell membranes. SN1 mediates electroneutral and bidirectional glutamine transport, and regulates the intracellular as well as the extracellular concentrations of glutamine. We hypothesize that SN1 participates in the glutamate/γ-aminobutyric acid (GABA)-glutamine cycle and regulates the amount of glutamine supplied to the neurons for replenishment of the neurotransmitter pools of glutamate and GABA. We also hypothesize that its activity on the plasma membrane is regulated by protein kinase C (PKC)-mediated phosphorylation and that SN1 activity has an impact on synaptic plasticity. This review discusses reports on the regulation of SN1 by PKC and presents a consolidated model for regulation and degradation of SN1 and the subsequent functional implications. As SN1 function is likely also regulated by PKC-mediated phosphorylation in peripheral organs, the same mechanisms may, thus, have impact on e.g., pH regulation in the kidney, urea formation in the liver, and insulin secretion in the pancreas.
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Affiliation(s)
- Lise Sofie H. Nissen-Meyer
- The Biotechnology Centre, University of Oslo, Oslo, Norway
- The Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
- *Correspondence: Lise Sofie H. Nissen-Meyer and Farrukh Abbas Chaudhry, The Institute of Basic Medical Sciences, University of Oslo, P.O. Box 1110 Blindern, 0317 Oslo, Norway e-mail: ;
| | - Farrukh Abbas Chaudhry
- The Biotechnology Centre, University of Oslo, Oslo, Norway
- The Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
- *Correspondence: Lise Sofie H. Nissen-Meyer and Farrukh Abbas Chaudhry, The Institute of Basic Medical Sciences, University of Oslo, P.O. Box 1110 Blindern, 0317 Oslo, Norway e-mail: ;
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109
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Biomarkers of cognitive dysfunction in traumatic brain injury. J Neural Transm (Vienna) 2013; 121:79-90. [DOI: 10.1007/s00702-013-1078-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Accepted: 07/30/2013] [Indexed: 12/11/2022]
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110
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Ramakrishnan L, Dalhoff Z, Fettig SL, Eggerichs MR, Nelson BE, Shrestha B, Elshikh AH, Karki P. Riluzole attenuates the effects of chemoconvulsants acting on glutamatergic and GABAergic neurotransmission in the planarian Dugesia tigrina. Eur J Pharmacol 2013; 718:493-501. [PMID: 23872399 DOI: 10.1016/j.ejphar.2013.07.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Revised: 07/03/2013] [Accepted: 07/04/2013] [Indexed: 01/01/2023]
Abstract
Planarians, the non-parasitic flatworms, display dose-dependent, distinct (C-like and corkscrew-like) hyperkinesias upon exposure to 0.001-10 mM aqueous solutions of glutamatergic agonists (L-glutamate and N-methyl-D-aspartate (NMDA)) and 0.001-5 mM concentrations of the glutamate decarboxylase (GAD) inhibitor (semicarbazide). In the planarian seizure-like activity (PSLA) experiments the three chemoconvulsants displayed the following order of potency (EC50): L-glutamate (0.6mM)>NMDA (1.4 mM)>semicarbazide (4.5mM). Planarian hyperkinesias behavior counting experiments also revealed that riluzole (0.001 to 1mM), an anti-convulsive agent, displayed no significant behavioral activity by itself, but attenuated hyperkinesias elicited by the three chemoconvulsants targeting either glutamatergic or GABAergic neurotransmission with the following order of potency (IC50): NMDA (44.7 µM)>semicarbazide (88.3 µM)>L-glutamate (160 µM). Further, (+)-MK-801, a specific NMDA antagonist, alleviated 3mM NMDA (47%) or 3mM L-glutamate (27%) induced planarian hyperkinesias. The results provide pharmacological evidence for the presence of glutamatergic receptor-like and semicarbazide sensitive functional GAD enzyme-like proteins in planaria in addition to demonstrating, for the first time, the anti-convulsive effects of riluzole in an invertebrate model. High performance liquid chromatography coupled with fluorescence detection (HPLC-F) analysis performed on planarian extracts post no drug treatment (control) or treatment with 3mM semicarbazide, combination of 3mM semicarbazide and 0.1 mM riluzole, or 0.1 mM riluzole revealed that 3 mM semicarbazide induced 35% decrease in the GABA levels and a combination of 3mM semicarbazide and 0.1 mM riluzole induced 42% decrease in glutamate levels with respect to the control group.
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Affiliation(s)
- Latha Ramakrishnan
- Department of Chemistry and Physics, Saint Cloud State University, Saint Cloud, MN 56301-4498, United States.
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111
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Kan MC, Wang WP, Yao GD, Li JT, Xie T, Wang W, Ma WQ. Anticonvulsant effect of dexmedetomidine in a rat model of self-sustaining status epilepticus with prolonged amygdala stimulation. Neurosci Lett 2013; 543:17-21. [DOI: 10.1016/j.neulet.2013.03.036] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Revised: 03/05/2013] [Accepted: 03/10/2013] [Indexed: 11/25/2022]
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112
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Zhou L, Huang J, Wang H, Luo J, Zeng L, Xiong K, Chen D. Expression of Glutamate and GABA during the Process of Rat Retinal Synaptic Plasticity Induced by Acute High Intraocular Pressure. Acta Histochem Cytochem 2013; 46:11-8. [PMID: 23554535 PMCID: PMC3596602 DOI: 10.1267/ahc.12029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Accepted: 11/12/2012] [Indexed: 11/30/2022] Open
Abstract
Acute high intraocular pressure (HIOP) can induce plastic changes of retinal synapses during which the expression of the presynaptic marker synaptophysin (SYN) has a distinct spatiotemporal pattern from the inner plexiform layer to the outer plexiform layer. We identified the types of neurotransmitters in the retina that participated in this process and determined the response of these neurotransmitters to HIOP induction. The model of acute HIOP was established by injecting normal saline into the anterior chamber of the rat eye. We found that the number of glutamate-positive cells increased successively from the inner part to the outer part of the retina (from the ganglion cell layer to the inner nuclear layer to the outer nuclear layer) after HIOP, which was similar to the spatiotemporal pattern of SYN expression (internally to externally) following HIOP. However, the distribution and intensity of GABA immunoreactivity in the retina did not change significantly at different survival time post injury and had no direct correlation with SYN expression. Our results suggested that the excitatory neurotransmitter glutamate might participate in the plastic process of retinal synapses following acute HIOP, but no evidence was found for the role of the inhibitory neurotransmitter GABA.
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Affiliation(s)
- Lihong Zhou
- Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University
| | - Jufang Huang
- Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University
| | - Hui Wang
- Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University
| | - Jia Luo
- Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University
| | - Leping Zeng
- Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University
| | - Kun Xiong
- Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University
| | - Dan Chen
- Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University
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113
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Calvetti D, Somersalo E. Quantitative in silico Analysis of Neurotransmitter Pathways Under Steady State Conditions. Front Endocrinol (Lausanne) 2013; 4:137. [PMID: 24115944 PMCID: PMC3792486 DOI: 10.3389/fendo.2013.00137] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 09/16/2013] [Indexed: 12/05/2022] Open
Abstract
The modeling of glutamate/GABA-glutamine cycling in the brain tissue involving astrocytes, glutamatergic and GABAergic neurons leads to a complex compartmentalized metabolic network that comprises neurotransmitter synthesis, shuttling, and degradation. Without advanced computational tools, it is difficult to quantitatively track possible scenarios and identify viable ones. In this article, we follow a sampling-based computational paradigm to analyze the biochemical network in a multi-compartment system modeling astrocytes, glutamatergic, and GABAergic neurons, and address some questions about the details of transmitter cycling, with particular emphasis on the ammonia shuttling between astrocytes and neurons, and the synthesis of transmitter GABA. More specifically, we consider the joint action of the alanine-lactate shuttle, the branched chain amino acid shuttle, and the glutamine-glutamate cycle, as well as the role of glutamate dehydrogenase (GDH) activity. When imposing a minimal amount of bound constraints on reaction and transport fluxes, a preferred stoichiometric steady state equilibrium requires an unrealistically high reductive GDH activity in neurons, indicating the need for additional bound constants which were included in subsequent computer simulations. The statistical flux balance analysis also suggests a stoichiometrically viable role for leucine transport as an alternative to glutamine for replenishing the glutamate pool in neurons.
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Affiliation(s)
- Daniela Calvetti
- Department of Mathematics, Applied Mathematics and Statistics, Case Western Reserve University, Cleveland, OH, USA
- *Correspondence: Daniela Calvetti, Department of Mathematics, Applied Mathematics and Statistics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA e-mail:
| | - Erkki Somersalo
- Department of Mathematics, Applied Mathematics and Statistics, Case Western Reserve University, Cleveland, OH, USA
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114
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Schousboe A, Bak LK, Waagepetersen HS. Astrocytic Control of Biosynthesis and Turnover of the Neurotransmitters Glutamate and GABA. Front Endocrinol (Lausanne) 2013; 4:102. [PMID: 23966981 PMCID: PMC3744088 DOI: 10.3389/fendo.2013.00102] [Citation(s) in RCA: 193] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 07/31/2013] [Indexed: 01/20/2023] Open
Abstract
Glutamate and GABA are the quantitatively major neurotransmitters in the brain mediating excitatory and inhibitory signaling, respectively. These amino acids are metabolically interrelated and at the same time they are tightly coupled to the intermediary metabolism including energy homeostasis. Astrocytes play a pivotal role in the maintenance of the neurotransmitter pools of glutamate and GABA since only these cells express pyruvate carboxylase, the enzyme required for de novo synthesis of the two amino acids. Such de novo synthesis is obligatory to compensate for catabolism of glutamate and GABA related to oxidative metabolism when the amino acids are used as energy substrates. This, in turn, is influenced by the extent to which the cycling of the amino acids between neurons and astrocytes may occur. This cycling is brought about by the glutamate/GABA - glutamine cycle the operation of which involves the enzymes glutamine synthetase (GS) and phosphate-activated glutaminase together with the plasma membrane transporters for glutamate, GABA, and glutamine. The distribution of these proteins between neurons and astrocytes determines the efficacy of the cycle and it is of particular importance that GS is exclusively expressed in astrocytes. It should be kept in mind that the operation of the cycle is associated with movement of ammonia nitrogen between the two cell types and different mechanisms which can mediate this have been proposed. This review is intended to delineate the above mentioned processes and to discuss quantitatively their relative importance in the homeostatic mechanisms responsible for the maintenance of optimal conditions for the respective neurotransmission processes to operate.
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Affiliation(s)
- Arne Schousboe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- *Correspondence: Arne Schousboe, Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark e-mail:
| | - Lasse K. Bak
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Helle S. Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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115
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Bhowmik M, Khanam R, Vohora D. Histamine H3 receptor antagonists in relation to epilepsy and neurodegeneration: a systemic consideration of recent progress and perspectives. Br J Pharmacol 2012; 167:1398-414. [PMID: 22758607 PMCID: PMC3514756 DOI: 10.1111/j.1476-5381.2012.02093.x] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 05/03/2012] [Accepted: 06/12/2012] [Indexed: 12/22/2022] Open
Abstract
The central histaminergic actions are mediated by H(1) , H(2) , H(3) and H(4) receptors. The histamine H(3) receptor regulates the release of histamine and a number of other neurotransmitters and thereby plays a role in cognitive and homeostatic processes. Elevated histamine levels suppress seizure activities and appear to confer neuroprotection. The H(3) receptors have a number of enigmatic features like constitutive activity, interspecies variation, distinct ligand binding affinities and differential distribution of prototypic splice variants in the CNS. Furthermore, this Gi/Go-protein-coupled receptor modulates several intracellular signalling pathways whose involvement in epilepsy and neurotoxicity are yet to be ascertained and hence represent an attractive target in the search for new anti-epileptogenic drugs. So far, H(3) receptor antagonists/inverse agonists have garnered a great deal of interest in view of their promising therapeutic properties in various CNS disorders including epilepsy and related neurotoxicity. However, a number of experiments have yielded opposing effects. This article reviews recent works that have provided evidence for diverse mechanisms of antiepileptic and neuroprotective effects that were observed in various experimental models both in vitro and in vivo. The likely reasons for the apparent disparities arising from the literature are also discussed with the aim of establishing a more reliable basis for the future use of H(3) receptor antagonists, thus improving their utility in epilepsy and associated neurotoxicity.
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Affiliation(s)
- M Bhowmik
- Neurobehavioral Pharmacology Laboratory, Department of Pharmacology, Faculty of Pharmacy, Jamia Hamdard (Hamdard University), New Delhi, India
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116
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Lange SC, Bak LK, Waagepetersen HS, Schousboe A, Norenberg MD. Primary cultures of astrocytes: their value in understanding astrocytes in health and disease. Neurochem Res 2012; 37:2569-88. [PMID: 22926576 DOI: 10.1007/s11064-012-0868-0] [Citation(s) in RCA: 126] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 08/01/2012] [Accepted: 08/01/2012] [Indexed: 12/26/2022]
Abstract
During the past few decades of astrocyte research it has become increasingly clear that astrocytes have taken a central position in all central nervous system activities. Much of our new understanding of astrocytes has been derived from studies conducted with primary cultures of astrocytes. Such cultures have been an invaluable tool for studying roles of astrocytes in physiological and pathological states. Many central astrocytic functions in metabolism, amino acid neurotransmission and calcium signaling were discovered using this tissue culture preparation and most of these observations were subsequently found in vivo. Nevertheless, primary cultures of astrocytes are an in vitro model that does not fully mimic the complex events occurring in vivo. Here we present an overview of the numerous contributions generated by the use of primary astrocyte cultures to uncover the diverse functions of astrocytes. Many of these discoveries would not have been possible to achieve without the use of astrocyte cultures. Additionally, we address and discuss the concerns that have been raised regarding the use of primary cultures of astrocytes as an experimental model system.
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Affiliation(s)
- Sofie C Lange
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
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117
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Romei C, Raiteri M, Raiteri L. GABA transporters mediate glycine release from cerebellum nerve endings: Roles of Ca2+channels, mitochondrial Na+/Ca2+ exchangers, vesicular GABA/glycine transporters and anion channels. Neurochem Int 2012; 61:133-40. [DOI: 10.1016/j.neuint.2012.05.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 04/18/2012] [Accepted: 05/01/2012] [Indexed: 01/03/2023]
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