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A single intracerebroventricular Aβ25–35 infusion leads to prolonged alterations in arginine metabolism in the rat hippocampus and prefrontal cortex. Neuroscience 2015; 298:367-79. [DOI: 10.1016/j.neuroscience.2015.04.034] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 04/03/2015] [Accepted: 04/14/2015] [Indexed: 12/21/2022]
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152
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McMahon SB, Russa FL, Bennett DLH. Crosstalk between the nociceptive and immune systems in host defence and disease. Nat Rev Neurosci 2015; 16:389-402. [DOI: 10.1038/nrn3946] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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153
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Rozas NS, Redell JB, Pita-Almenar JD, Mckenna J, Moore AN, Gambello MJ, Dash PK. Intrahippocampal glutamine administration inhibits mTORC1 signaling and impairs long-term memory. ACTA ACUST UNITED AC 2015; 22:239-46. [PMID: 25878136 PMCID: PMC4408772 DOI: 10.1101/lm.038265.115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 02/13/2015] [Indexed: 11/25/2022]
Abstract
The mechanistic Target of Rapamycin Complex 1 (mTORC1), a key regulator of protein synthesis and cellular growth, is also required for long-term memory formation. Stimulation of mTORC1 signaling is known to be dependent on the availability of energy and growth factors, as well as the presence of amino acids. In vitro studies using serum- and amino acid-starved cells have reported that glutamine addition can either stimulate or repress mTORC1 activity, depending on the particular experimental system that was used. However, these experiments do not directly address the effect of glutamine on mTORC1 activity under physiological conditions in nondeprived cells in vivo. We present experimental results indicating that intrahippocampal administration of glutamine to rats reduces mTORC1 activity. Moreover, post-training administration of glutamine impairs long-term spatial memory formation, while coadministration of glutamine with leucine had no influence on memory. Intracellular recordings in hippocampal slices showed that glutamine did not alter either excitatory or inhibitory synaptic activity, suggesting that the observed memory impairments may not result from conversion of glutamine to either glutamate or GABA. Taken together, these findings indicate that glutamine can decrease mTORC1 activity in the brain and may have implications for treatments of neurological diseases associated with high mTORC1 signaling.
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Affiliation(s)
- Natalia S Rozas
- Department of Neurobiology and Anatomy, The University of Texas Medical School, Houston, Texas 77225, USA
| | - John B Redell
- Department of Neurobiology and Anatomy, The University of Texas Medical School, Houston, Texas 77225, USA
| | - Juan D Pita-Almenar
- Department of Neurobiology and Anatomy, The University of Texas Medical School, Houston, Texas 77225, USA
| | - James Mckenna
- Department of Human Genetics, Emory University, Atlanta, Georgia 30322, USA
| | - Anthony N Moore
- Department of Neurobiology and Anatomy, The University of Texas Medical School, Houston, Texas 77225, USA
| | - Michael J Gambello
- Department of Human Genetics, Emory University, Atlanta, Georgia 30322, USA
| | - Pramod K Dash
- Department of Neurobiology and Anatomy, The University of Texas Medical School, Houston, Texas 77225, USA
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154
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Metabolomic identification of biochemical changes induced by fluoxetine and imipramine in a chronic mild stress mouse model of depression. Sci Rep 2015; 5:8890. [PMID: 25749400 PMCID: PMC4352870 DOI: 10.1038/srep08890] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 02/10/2015] [Indexed: 02/07/2023] Open
Abstract
Metabolomics was applied to a C57BL/6N mouse model of chronic unpredictable mild stress (CMS). Such mice were treated with two antidepressants from different categories: fluoxetine and imipramine. Metabolic profiling of the hippocampus was performed using gas chromatography-mass spectrometry analysis on samples prepared under optimized conditions, followed by principal component analysis, partial least squares-discriminant analysis, and pair-wise orthogonal projections to latent structures discriminant analyses. Body weight measurement and behavior tests including an open field test and the forced swimming test were completed with the mice as a measure of the phenotypes of depression and antidepressive effects. As a result, 23 metabolites that had been differentially expressed among the control, CMS, and antidepressant-treated groups demonstrated that amino acid metabolism, energy metabolism, adenosine receptors, and neurotransmitters are commonly perturbed by drug treatment. Potential predictive markers for treatment effect were identified: myo-inositol for fluoxetine and lysine and oleic acid for imipramine. Collectively, the current study provides insights into the molecular mechanisms of the antidepressant effects of two widely used medications.
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155
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Crosstalk Among Disrupted Glutamatergic and Cholinergic Homeostasis and Inflammatory Response in Mechanisms Elicited by Proline in Astrocytes. Mol Neurobiol 2015; 53:1065-1079. [PMID: 25579384 DOI: 10.1007/s12035-014-9067-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Accepted: 12/29/2014] [Indexed: 12/12/2022]
Abstract
Hyperprolinemias are inherited disorder of proline (Pro) metabolism. Patients affected may present neurological manifestations, but the mechanisms of neural excitotoxicity elicited by hyperprolinemia are far from being understood. Considering that the astrocytes are important players in neurological disorders, the aim of the present work was to study the effects 1 mM Pro on glutamatergic and inflammatory parameters in cultured astrocytes from cerebral cortex of rats, exploring some molecular mechanisms underlying the disrupted homeostasis of astrocytes exposed to this toxic Pro concentration. We showed that cortical astrocytes of rats exposed to 1 mM Pro presented significantly elevated extracellular glutamate and glutamine levels, suggesting glutamate excitotoxicity. The excess of glutamate elicited by Pro together with increased glutamate uptake and upregulated glutamine synthetase (GS) activity supported misregulated glutamate homeostasis in astrocytic cells. High Pro levels also induced production/release of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6. We also evidenced misregulation of cholinergic anti-inflammatory system with increased acetylcholinesterase (AChE) activity and decreased acetylcholine (ACh) levels, contributing to the inflammatory status in Pro-treated astrocytes. Our findings highlighted a crosstalk among disrupted glutamate homeostasis, cholinergic mechanisms, and inflammatory cytokines, since ionotropic (DL-AP5 and CNQX) and metabotropic (MCPG and MPEP) glutamate antagonists were able to restore the extracellular glutamate and glutamine levels; downregulate TNFα and IL6 production/release, modulate GS and AChE activities; and restore ACh levels. Otherwise, the non-steroidal anti-inflammatory drugs nimesulide, acetylsalicylic acid, ibuprofen, and diclofenac sodium decreased the extracellular glutamate and glutamine levels, downregulated GS and AChE activities, and restored ACh levels in Pro-treated astrocytes. Altogether, our results evidence that the vulnerability of metabolic homeostasis in cortical astrocytes might have important implications in the neurotoxicity of Pro.
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156
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The separation of Gln and Glu in STEAM: a comparison study using short and long TEs/TMs at 3 and 7 T. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2015; 28:395-405. [DOI: 10.1007/s10334-014-0479-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 12/12/2014] [Accepted: 12/15/2014] [Indexed: 10/24/2022]
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Scofield MD, Kalivas PW. Astrocytic dysfunction and addiction: consequences of impaired glutamate homeostasis. Neuroscientist 2014; 20:610-22. [PMID: 24496610 PMCID: PMC4913887 DOI: 10.1177/1073858413520347] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Addiction is characterized as a chronic relapsing disorder whereby addicted individuals persistently engage in drug seeking and use despite profound negative consequences. The results of studies using animal models of addiction and relapse indicate that drug seeking is mediated by alterations in cortico-accumbal plasticity induced by chronic drug exposure. Among the maladaptive responses to drug exposure are long-lasting alterations in the expression of proteins localized to accumbal astrocytes, which are responsible for maintaining glutamate homeostasis. These alterations engender an aberrant potentiation of glutamate transmission in the cortico-accumbens circuit that is linked to the reinstatement of drug seeking. Accordingly, pharmacological restoration of glutamate homeostasis functions as an efficient method of reversing drug-induced plasticity and inhibiting drug seeking in both rodents and humans.
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Affiliation(s)
- Michael D Scofield
- Medical University of South Carolina, Charleston, SC, USA, Department of Neurosciences
| | - Peter W Kalivas
- Medical University of South Carolina, Charleston, SC, USA, Department of Neurosciences
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158
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Hägglund MGA, Hellsten SV, Bagchi S, Philippot G, Löfqvist E, Nilsson VCO, Almkvist I, Karlsson E, Sreedharan S, Tafreshiha A, Fredriksson R. Transport of L-glutamine, L-alanine, L-arginine and L-histidine by the neuron-specific Slc38a8 (SNAT8) in CNS. J Mol Biol 2014; 427:1495-1512. [PMID: 25451601 DOI: 10.1016/j.jmb.2014.10.016] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 09/30/2014] [Accepted: 10/17/2014] [Indexed: 11/19/2022]
Abstract
Glutamine transporters are important for regulating levels of glutamate and GABA in the brain. To date, six members of the SLC38 family (SNATs) have been characterized and functionally subdivided them into System A (SNAT1, SNAT2 and SNAT4) and System N (SNAT3, SNAT5 and SNAT7). Here we present the first functional characterization of SLC38A8, one of the previous orphan transporters from the family, and we suggest that the encoded protein should be named SNAT8 to adhere with the SNAT nomenclature. We show that SLC38A8 has preference for transporting L-glutamine, L-alanine, L-arginine, L-histidine and L-aspartate using a Na+-dependent transport mechanism and that the functional characteristics of SNAT8 have highest similarity to the known System A transporters. We also provide a comprehensive central nervous system expression profile in mouse brain for the Slc38a8 gene and the SNAT8 protein. We show that Slc38a8 (SNAT8) is expressed in all neurons, both excitatory and inhibitory, in mouse brain using in situ hybridization and immunohistochemistry. Furthermore, proximity ligation assay shows highly similar subcellular expression of SNAT7 and SNAT8. In conclusion, the neuronal SLC38A8 has a broad amino acid transport profile and is the first identified neuronal System A transporter. This suggests a key role of SNAT8 in the glutamine/glutamate (GABA) cycle in the brain.
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Affiliation(s)
- Maria G A Hägglund
- Department of Neuroscience, Functional Pharmacology, Uppsala University, Husargatan 3, SE-75124 Uppsala, Sweden.
| | - Sofie V Hellsten
- Department of Neuroscience, Functional Pharmacology, Uppsala University, Husargatan 3, SE-75124 Uppsala, Sweden.
| | - Sonchita Bagchi
- Department of Neuroscience, Functional Pharmacology, Uppsala University, Husargatan 3, SE-75124 Uppsala, Sweden.
| | - Gaëtan Philippot
- Department of Neuroscience, Functional Pharmacology, Uppsala University, Husargatan 3, SE-75124 Uppsala, Sweden.
| | - Erik Löfqvist
- Department of Neuroscience, Functional Pharmacology, Uppsala University, Husargatan 3, SE-75124 Uppsala, Sweden.
| | - Victor C O Nilsson
- Department of Neuroscience, Functional Pharmacology, Uppsala University, Husargatan 3, SE-75124 Uppsala, Sweden.
| | - Ingrid Almkvist
- Department of Neuroscience, Functional Pharmacology, Uppsala University, Husargatan 3, SE-75124 Uppsala, Sweden.
| | - Edvin Karlsson
- Department of Neuroscience, Functional Pharmacology, Uppsala University, Husargatan 3, SE-75124 Uppsala, Sweden.
| | - Smitha Sreedharan
- Department of Neuroscience, Functional Pharmacology, Uppsala University, Husargatan 3, SE-75124 Uppsala, Sweden.
| | - Atieh Tafreshiha
- Department of Neuroscience, Functional Pharmacology, Uppsala University, Husargatan 3, SE-75124 Uppsala, Sweden.
| | - Robert Fredriksson
- Department of Neuroscience, Functional Pharmacology, Uppsala University, Husargatan 3, SE-75124 Uppsala, Sweden.
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Lee IP, Evans AK, Yang C, Works MG, Kumar V, De Miguel Z, Manley NC, Sapolsky RM. Toxoplasma gondii is dependent on glutamine and alters migratory profile of infected host bone marrow derived immune cells through SNAT2 and CXCR4 pathways. PLoS One 2014; 9:e109803. [PMID: 25299045 PMCID: PMC4192591 DOI: 10.1371/journal.pone.0109803] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 09/12/2014] [Indexed: 01/16/2023] Open
Abstract
The obligate intracellular parasite, Toxoplasma gondii, disseminates through its host inside infected immune cells. We hypothesize that parasite nutrient requirements lead to manipulation of migratory properties of the immune cell. We demonstrate that 1) T. gondii relies on glutamine for optimal infection, replication and viability, and 2) T. gondii-infected bone marrow-derived dendritic cells (DCs) display both “hypermotility” and “enhanced migration” to an elevated glutamine gradient in vitro. We show that glutamine uptake by the sodium-dependent neutral amino acid transporter 2 (SNAT2) is required for this enhanced migration. SNAT2 transport of glutamine is also a significant factor in the induction of migration by the small cytokine stromal cell-derived factor-1 (SDF-1) in uninfected DCs. Blocking both SNAT2 and C-X-C chemokine receptor 4 (CXCR4; the unique receptor for SDF-1) blocks hypermotility and the enhanced migration in T. gondii-infected DCs. Changes in host cell protein expression following T. gondii infection may explain the altered migratory phenotype; we observed an increase of CD80 and unchanged protein level of CXCR4 in both T. gondii-infected and lipopolysaccharide (LPS)-stimulated DCs. However, unlike activated DCs, SNAT2 expression in the cytosol of infected cells was also unchanged. Thus, our results suggest an important role of glutamine transport via SNAT2 in immune cell migration and a possible interaction between SNAT2 and CXCR4, by which T. gondii manipulates host cell motility.
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Affiliation(s)
- I-Ping Lee
- Department of Biology, Stanford University, Stanford, California, United States of America
- * E-mail:
| | - Andrew K. Evans
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Cissy Yang
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Melissa G. Works
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Vineet Kumar
- School of Biological Sciences, Nanyang Technological University, Singapore, Republic of Singapore
| | - Zurine De Miguel
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Nathan C. Manley
- Department of Biology, Stanford University, Stanford, California, United States of America
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, California, United States of America
- Stanford Stroke Center and Stanford Institute for Neuro-Innovation and Translational Neurosciences, Stanford University School of Medicine, Stanford, California, United States of America
| | - Robert M. Sapolsky
- Department of Biology, Stanford University, Stanford, California, United States of America
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, California, United States of America
- Stanford Stroke Center and Stanford Institute for Neuro-Innovation and Translational Neurosciences, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, United States of America
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160
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Gruol DL, Vo K, Bray JG. Increased astrocyte expression of IL-6 or CCL2 in transgenic mice alters levels of hippocampal and cerebellar proteins. Front Cell Neurosci 2014; 8:234. [PMID: 25177271 PMCID: PMC4132577 DOI: 10.3389/fncel.2014.00234] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 07/25/2014] [Indexed: 12/16/2022] Open
Abstract
Emerging research has identified that neuroimmune factors are produced by cells of the central nervous system (CNS) and play critical roles as regulators of CNS function, directors of neurodevelopment and responders to pathological processes. A wide range of neuroimmune factors are produced by CNS cells, primarily the glial cells, but the role of specific neuroimmune factors and their glial cell sources in CNS biology and pathology have yet to be fully elucidated. We have used transgenic mice that express elevated levels of a specific neuroimmune factor, the cytokine IL-6 or the chemokine CCL2, through genetic modification of astrocyte expression to identify targets of astrocyte produced IL-6 or CCL2 at the protein level. We found that in non-transgenic mice constitutive expression of IL-6 and CCL2 occurs in the two CNS regions studied, the hippocampus and cerebellum, as measured by ELISA. In the CCL2 transgenic mice elevated levels of CCL2 were evident in the hippocampus and cerebellum, whereas in the IL-6 transgenic mice, elevated levels of IL-6 were only evident in the cerebellum. Western blot analysis of the cellular and synaptic proteins in the hippocampus and cerebellum of the transgenic mice showed that the elevated levels of CCL2 or IL-6 resulted in alterations in the levels of specific proteins and that these actions differed for the two neuroimmune factors and for the two brain regions. These results are consistent with cell specific profiles of action for IL-6 and CCL2, actions that may be an important aspect of their respective roles in CNS physiology and pathophysiology.
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Affiliation(s)
- Donna L Gruol
- Molecular and Cellular Neuroscience Department, The Scripps Research Institute La Jolla, CA, USA
| | - Khanh Vo
- Molecular and Cellular Neuroscience Department, The Scripps Research Institute La Jolla, CA, USA
| | - Jennifer G Bray
- Department of Biology, University of Wisconsin-Stevens Point Stevens Point, WI, USA
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161
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Büchel J, Bartosova M, Eich G, Wittenberger T, Klein-Hitpass L, Steppan S, Hackert T, Schaefer F, Passlick-Deetjen J, Schmitt CP. Interference of peritoneal dialysis fluids with cell cycle mechanisms. Perit Dial Int 2014; 35:259-74. [PMID: 25082841 DOI: 10.3747/pdi.2013.00010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 01/28/2014] [Indexed: 12/26/2022] Open
Abstract
INTRODUCTION Peritoneal dialysis fluids (PDF) differ with respect to osmotic and buffer compound, and pH and glucose degradation products (GDP) content. The impact on peritoneal membrane integrity is still insufficiently described. We assessed global genomic effects of PDF in primary human peritoneal mesothelial cells (PMC) by whole genome analyses, quantitative real-time polymerase chain reaction (RT-PCR) and functional measurements. METHODS PMC isolated from omentum of non-uremic patients were incubated with conventional single chamber PDF (CPDF), lactate- (LPDF), bicarbonate- (BPDF) and bicarbonate/lactate-buffered double-chamber PDF (BLPDF), icodextrin (IPDF) and amino acid PDF (APDF), diluted 1:1 with medium. Affymetrix GeneChip U133Plus2.0 (Affymetrix, CA, USA) and quantitative RT-PCR were applied; cell viability was assessed by proliferation assays. RESULTS The number of differentially expressed genes compared to medium was 464 with APDF, 208 with CPDF, 169 with IPDF, 71 with LPDF, 45 with BPDF and 42 with BLPDF. Out of these genes 74%, 73%, 79%, 72%, 47% and 57% were downregulated. Gene Ontology (GO) term annotations mainly revealed associations with cell cycle (p = 10(-35)), cell division, mitosis, and DNA replication. One hundred and eighteen out of 249 probe sets detecting genes involved in cell cycle/division were suppressed, with APDF-treated PMC being affected the most regarding absolute number and degree, followed by CPDF and IPDF. Bicarbonate-containing PDF and BLPDF-treated PMC were affected the least. Quantitative RT-PCR measurements confirmed microarray findings for key cell cycle genes (CDK1/CCNB1/CCNE2/AURKA/KIF11/KIF14). Suppression was lowest for BPDF and BLPDF, they upregulated CCNE2 and SMC4. All PDF upregulated 3 out of 4 assessed cell cycle repressors (p53/BAX/p21). Cell viability scores confirmed gene expression results, being 79% of medium for LPDF, 101% for BLPDF, 51% for CPDF and 23% for IPDF. Amino acid-containing PDF (84%) incubated cells were as viable as BPDF (86%). CONCLUSION In conclusion, PD solutions substantially differ with regard to their gene regulating profile and impact on vital functions of PMC, i.e. on cells known to be essential for peritoneal membrane homeostasis.
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Affiliation(s)
- Janine Büchel
- Fresenius Medical Care Deutschland GmbH, Bad Homburg, Germany
| | - Maria Bartosova
- University Hospital for Pediatrics & Adolescent Medicine, University of Heidelberg, Heidelberg, Germany
| | - Gwendolyn Eich
- University Hospital for Pediatrics & Adolescent Medicine, University of Heidelberg, Heidelberg, Germany
| | | | - Ludger Klein-Hitpass
- University of Duisburg-Essen, Faculty of Medicine, Institute of Cell Biology, Essen, Germany
| | - Sonja Steppan
- Fresenius Medical Care Deutschland GmbH, Bad Homburg, Germany
| | - Thilo Hackert
- Department of Surgery, University of Heidelberg, Heidelberg, Germany
| | - Franz Schaefer
- University Hospital for Pediatrics & Adolescent Medicine, University of Heidelberg, Heidelberg, Germany
| | | | - Claus P Schmitt
- University Hospital for Pediatrics & Adolescent Medicine, University of Heidelberg, Heidelberg, Germany
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163
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Bernstein HG, Bannier J, Meyer-Lotz G, Steiner J, Keilhoff G, Dobrowolny H, Walter M, Bogerts B. Distribution of immunoreactive glutamine synthetase in the adult human and mouse brain. Qualitative and quantitative observations with special emphasis on extra-astroglial protein localization. J Chem Neuroanat 2014; 61-62:33-50. [PMID: 25058171 DOI: 10.1016/j.jchemneu.2014.07.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 07/14/2014] [Accepted: 07/14/2014] [Indexed: 12/20/2022]
Abstract
Glutamine synthetase catalyzes the ATP-dependent condensation of ammonia and glutamate to form glutamine, thus playing a pivotal role in glutamate and glutamine homoeostasis. Despite a plethora of studies on this enzyme, knowledge about the regional and cellular distribution of this enzyme in human brain is still fragmentary. Therefore, we mapped fourteen post-mortem brains of psychically healthy individuals for the distribution of the glutamine synthetase immunoreactive protein. It was found that glutamine synthetase immunoreactivity is expressed in multiple gray and white matter astrocytes, but also in oligodendrocytes, ependymal cells and certain neurons. Since a possible extra-astrocytic expression of glutamine synthetase is highly controversial, we paid special attention to its appearance in oligodendrocytes and neurons. By double immunolabeling of mouse brain slices and cultured mouse brain cells for glutamine synthetase and cell-type-specific markers we provide evidence that besides astrocytes subpopulations of oligodendrocytes, microglial cells and neurons express glutamine synthetase. Moreover, we show that glutamine synthetase-immunopositive neurons are not randomly distributed throughout human and mouse brain, but represent a subpopulation of nitrergic (i.e. neuronal nitric oxide synthase expressing) neurons. Possible functional implications of an extra-astrocytic localization of glutamine synthetase are discussed.
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Affiliation(s)
- Hans-Gert Bernstein
- Department of Psychiatry, Otto-von-Guericke University, Faculty of Medicine, Magdeburg, Germany.
| | - Jana Bannier
- Department of Psychiatry, Otto-von-Guericke University, Faculty of Medicine, Magdeburg, Germany
| | - Gabriela Meyer-Lotz
- Department of Psychiatry, Otto-von-Guericke University, Faculty of Medicine, Magdeburg, Germany
| | - Johann Steiner
- Department of Psychiatry, Otto-von-Guericke University, Faculty of Medicine, Magdeburg, Germany
| | - Gerburg Keilhoff
- Institute of Biochemistry and Cell Biology, Otto-von-Guericke University, Faculty of Medicine, Magdeburg, Germany
| | - Henrik Dobrowolny
- Department of Psychiatry, Otto-von-Guericke University, Faculty of Medicine, Magdeburg, Germany
| | - Martin Walter
- Department of Psychiatry, Otto-von-Guericke University, Faculty of Medicine, Magdeburg, Germany; Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Bernhard Bogerts
- Department of Psychiatry, Otto-von-Guericke University, Faculty of Medicine, Magdeburg, Germany
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164
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Effects of acute phencyclidine administration on arginine metabolism in the hippocampus and prefrontal cortex in rats. Neuropharmacology 2014; 81:195-205. [DOI: 10.1016/j.neuropharm.2014.02.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 01/03/2014] [Accepted: 02/05/2014] [Indexed: 12/19/2022]
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165
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Liubinas SV, O'Brien TJ, Moffat BM, Drummond KJ, Morokoff AP, Kaye AH. Tumour associated epilepsy and glutamate excitotoxicity in patients with gliomas. J Clin Neurosci 2014; 21:899-908. [PMID: 24746886 DOI: 10.1016/j.jocn.2014.02.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Accepted: 02/22/2014] [Indexed: 02/04/2023]
Abstract
Tumour associated epilepsy (TAE) is common, debilitating and often not successfully controlled by surgical resection of the tumour and administration of multiple anti-epileptic drugs. It represents a cause of significant lost quality of life in an incurable disease and is therefore an important subject for ongoing research. The pathogenesis of TAE is likely to be multifactorial and involve, on the microscopic level, the interaction of genetic factors, changes in the peritumoural microenvironment, alterations in synaptic neurotransmitter release and re-uptake, and the excitotoxic effects of glutamate. On a macroscopic level, the occurrence of TAE is likely to be influenced by tumour size, location and interaction with environmental factors. The optimal treatment of TAE requires a multi-disciplinary approach with input from neurosurgeons, neurologists, radiologists, pathologists and basic scientists. This article reviews the current literature regarding the incidence, treatment, and aetiology of TAE.
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Affiliation(s)
- Simon V Liubinas
- Department of Neurosurgery, The Royal Melbourne Hospital, Grattan Street, Parkville, VIC 3050, Australia; Department of Surgery (RMH/WH), The University of Melbourne, Parkville, VIC, Australia.
| | - Terence J O'Brien
- Department of Medicine (RMH/WH), The University of Melbourne, Parkville, VIC, Australia
| | - Bradford M Moffat
- Department of Radiology (RMH/WH), The University of Melbourne, Parkville, VIC, Australia
| | - Katharine J Drummond
- Department of Neurosurgery, The Royal Melbourne Hospital, Grattan Street, Parkville, VIC 3050, Australia; Department of Surgery (RMH/WH), The University of Melbourne, Parkville, VIC, Australia
| | - Andrew P Morokoff
- Department of Neurosurgery, The Royal Melbourne Hospital, Grattan Street, Parkville, VIC 3050, Australia; Department of Surgery (RMH/WH), The University of Melbourne, Parkville, VIC, Australia
| | - Andrew H Kaye
- Department of Neurosurgery, The Royal Melbourne Hospital, Grattan Street, Parkville, VIC 3050, Australia; Department of Surgery (RMH/WH), The University of Melbourne, Parkville, VIC, Australia
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Henriksen LT, Nersting J, Raja RA, Frandsen TL, Rosthøj S, Schrøder H, Albertsen BK. Cerebrospinal fluid asparagine depletion during pegylated asparaginase therapy in children with acute lymphoblastic leukaemia. Br J Haematol 2014; 166:213-20. [DOI: 10.1111/bjh.12865] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Accepted: 02/25/2014] [Indexed: 11/28/2022]
Affiliation(s)
| | - Jacob Nersting
- Department of Paediatric and Adolescent Medicine; University Hospital Rigshospitalet; Copenhagen Denmark
| | - Raheel A. Raja
- Department of Paediatric and Adolescent Medicine; University Hospital Rigshospitalet; Copenhagen Denmark
| | - Thomas L. Frandsen
- Department of Paediatric and Adolescent Medicine; University Hospital Rigshospitalet; Copenhagen Denmark
| | - Steen Rosthøj
- Department of Paediatrics; Aalborg University Hospital; Aalborg Denmark
| | - Henrik Schrøder
- Department of Paediatrics; Aarhus University Hospital; Aarhus N Denmark
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Maltezos S, Horder J, Coghlan S, Skirrow C, O'Gorman R, Lavender TJ, Mendez MA, Mehta M, Daly E, Xenitidis K, Paliokosta E, Spain D, Pitts M, Asherson P, Lythgoe DJ, Barker GJ, Murphy DG. Glutamate/glutamine and neuronal integrity in adults with ADHD: a proton MRS study. Transl Psychiatry 2014; 4:e373. [PMID: 24643164 PMCID: PMC3966039 DOI: 10.1038/tp.2014.11] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 01/06/2014] [Accepted: 01/09/2014] [Indexed: 01/19/2023] Open
Abstract
There is increasing evidence that abnormalities in glutamate signalling may contribute to the pathophysiology of attention-deficit hyperactivity disorder (ADHD). Proton magnetic resonance spectroscopy ([1H]MRS) can be used to measure glutamate, and also its metabolite glutamine, in vivo. However, few studies have investigated glutamate in the brain of adults with ADHD naive to stimulant medication. Therefore, we used [1H]MRS to measure the combined signal of glutamate and glutamine (Glu+Gln; abbreviated as Glx) along with other neurometabolites such as creatine (Cr), N-acetylaspartate (NAA) and choline. Data were acquired from three brain regions, including two implicated in ADHD-the basal ganglia (caudate/striatum) and the dorsolateral prefrontal cortex (DLPFC)-and one 'control' region-the medial parietal cortex. We compared 40 adults with ADHD, of whom 24 were naive for ADHD medication, whereas 16 were currently on stimulants, against 20 age, sex and IQ-matched healthy controls. We found that compared with controls, adult ADHD participants had a significantly lower concentration of Glx, Cr and NAA in the basal ganglia and Cr in the DLPFC, after correction for multiple comparisons. There were no differences between stimulant-treated and treatment-naive ADHD participants. In people with untreated ADHD, lower basal ganglia Glx was significantly associated with more severe symptoms of inattention. There were no significant differences in the parietal 'control' region. We suggest that subcortical glutamate and glutamine have a modulatory role in ADHD adults; and that differences in glutamate-glutamine levels are not explained by use of stimulant medication.
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Affiliation(s)
- S Maltezos
- Adult ADHD Service, The Maudsley Hospital, London, UK,King's College London, Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, London, UK
| | - J Horder
- King's College London, Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, London, UK,King's College London, Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, PO Box 50, London SE5 8AF, UK. E-mail:
| | - S Coghlan
- King's College London, Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, London, UK
| | - C Skirrow
- King's College London, MRC Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, London, UK
| | - R O'Gorman
- King's College London, Department of Neuroimaging, Institute of Psychiatry, London, UK
| | - T J Lavender
- King's College London, Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, London, UK
| | - M A Mendez
- King's College London, Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, London, UK,Autism Assessment and Behavioural Genetics Clinic, South London and Maudsley NHS Foundation Trust, Bethlem Royal Hospital, Beckenham, UK
| | - M Mehta
- King's College London, Department of Neuroimaging, Institute of Psychiatry, London, UK
| | - E Daly
- King's College London, Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, London, UK
| | - K Xenitidis
- Adult ADHD Service, The Maudsley Hospital, London, UK,King's College London, Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, London, UK
| | - E Paliokosta
- Adult ADHD Service, The Maudsley Hospital, London, UK
| | - D Spain
- King's College London, Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, London, UK,Autism Assessment and Behavioural Genetics Clinic, South London and Maudsley NHS Foundation Trust, Bethlem Royal Hospital, Beckenham, UK
| | - M Pitts
- Adult ADHD Service, The Maudsley Hospital, London, UK
| | - P Asherson
- Adult ADHD Service, The Maudsley Hospital, London, UK,King's College London, MRC Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, London, UK
| | - D J Lythgoe
- King's College London, Department of Neuroimaging, Institute of Psychiatry, London, UK
| | - G J Barker
- King's College London, Department of Neuroimaging, Institute of Psychiatry, London, UK
| | - D G Murphy
- King's College London, Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, London, UK,Autism Assessment and Behavioural Genetics Clinic, South London and Maudsley NHS Foundation Trust, Bethlem Royal Hospital, Beckenham, UK,Sackler Institute for Translational Neurodevelopment, Institute of Psychiatry, King's College London, London, UK
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168
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Panosyan EH, Wang Y, Xia P, Lee WNP, Pak Y, Laks DR, Lin HJ, Moore TB, Cloughesy TF, Kornblum HI, Lasky JL. Asparagine depletion potentiates the cytotoxic effect of chemotherapy against brain tumors. Mol Cancer Res 2014; 12:694-702. [PMID: 24505127 DOI: 10.1158/1541-7786.mcr-13-0576] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
UNLABELLED Targeting amino acid metabolism has therapeutic implications for aggressive brain tumors. Asparagine is an amino acid that is synthesized by normal cells. However, some cancer cells lack asparagine synthetase (ASNS), the key enzyme for asparagine synthesis. Asparaginase (ASNase) contributes to eradication of acute leukemia by decreasing asparagine levels in serum and cerebrospinal fluid. However, leukemic cells may become ASNase-resistant by upregulating ASNS. High expression of ASNS has also been associated with biologic aggressiveness of other cancers, including gliomas. Here, the impact of enzymatic depletion of asparagine on proliferation of brain tumor cells was determined. ASNase was used as monotherapy or in combination with conventional chemotherapeutic agents. Viability assays for ASNase-treated cells demonstrated significant growth reduction in multiple cell lines. This effect was reversed by glutamine in a dose-dependent manner--as expected, because glutamine is the main amino group donor for asparagine synthesis. ASNase treatment also reduced sphere formation by medulloblastoma and primary glioblastoma cells. ASNase-resistant glioblastoma cells exhibited elevated levels of ASNS mRNA. ASNase cotreatment significantly enhanced gemcitabine or etoposide cytotoxicity against glioblastoma cells. Xenograft tumors in vivo showed no significant response to ASNase monotherapy and little response to temozolomide alone. However, combinatorial therapy with ASNase and temozolomide resulted in significant growth suppression for an extended duration of time. Taken together, these findings indicate that amino acid depletion warrants further investigation as adjunctive therapy for brain tumors. IMPLICATIONS Findings have potential impact for providing adjuvant means to enhance brain tumor chemotherapy.
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Affiliation(s)
- Eduard H Panosyan
- Authors' Affiliations: Department of Pediatrics, Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, Torrance; Departments of 2Psychiatry and Molecular and Medical Pharmacology and 3Pediatrics; and 4The Jonsson Comprehensive Cancer Center, University of California Los Angeles (UCLA), Los Angeles, California
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169
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de la Monte SM, Kril JJ. Human alcohol-related neuropathology. Acta Neuropathol 2014; 127:71-90. [PMID: 24370929 DOI: 10.1007/s00401-013-1233-3] [Citation(s) in RCA: 250] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 12/12/2013] [Accepted: 12/13/2013] [Indexed: 02/08/2023]
Abstract
Alcohol-related diseases of the nervous system are caused by excessive exposures to alcohol, with or without co-existing nutritional or vitamin deficiencies. Toxic and metabolic effects of alcohol (ethanol) vary with brain region, age/developmental stage, dose, and duration of exposures. In the mature brain, heavy chronic or binge alcohol exposures can cause severe debilitating diseases of the central and peripheral nervous systems, and skeletal muscle. Most commonly, long-standing heavy alcohol abuse leads to disproportionate loss of cerebral white matter and impairments in executive function. The cerebellum (especially the vermis), cortical-limbic circuits, skeletal muscle, and peripheral nerves are also important targets of chronic alcohol-related metabolic injury and degeneration. Although all cell types within the nervous system are vulnerable to the toxic, metabolic, and degenerative effects of alcohol, astrocytes, oligodendrocytes, and synaptic terminals are major targets, accounting for the white matter atrophy, neural inflammation and toxicity, and impairments in synaptogenesis. Besides chronic degenerative neuropathology, alcoholics are predisposed to develop severe potentially life-threatening acute or subacute symmetrical hemorrhagic injury in the diencephalon and brainstem due to thiamine deficiency, which exerts toxic/metabolic effects on glia, myelin, and the microvasculature. Alcohol also has devastating neurotoxic and teratogenic effects on the developing brain in association with fetal alcohol spectrum disorder/fetal alcohol syndrome. Alcohol impairs function of neurons and glia, disrupting a broad array of functions including neuronal survival, cell migration, and glial cell (astrocytes and oligodendrocytes) differentiation. Further progress is needed to better understand the pathophysiology of this exposure-related constellation of nervous system diseases and better correlate the underlying pathology with in vivo imaging and biochemical lesions.
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170
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Linne ML, Jalonen TO. Astrocyte-neuron interactions: from experimental research-based models to translational medicine. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 123:191-217. [PMID: 24560146 DOI: 10.1016/b978-0-12-397897-4.00005-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In this chapter, we review the principal astrocyte functions and the interactions between neurons and astrocytes. We then address how the experimentally observed functions have been verified in computational models and review recent experimental literature on astrocyte-neuron interactions. Benefits of computational neuroscience work are highlighted through selected studies with neurons and astrocytes by analyzing the existing models qualitatively and assessing the relevance of these models to experimental data. Common strategies to mathematical modeling and computer simulation in neuroscience are summarized for the nontechnical reader. The astrocyte-neuron interactions are then further illustrated by examples of some neurological and neurodegenerative diseases, where the miscommunication between glia and neurons is found to be increasingly important.
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Affiliation(s)
- Marja-Leena Linne
- Computational Neuroscience Group, Department of Signal Processing, Tampere University of Technology, Tampere, Finland
| | - Tuula O Jalonen
- Department of Physiology and Neuroscience, St. George's University, School of Medicine, Grenada, West Indies
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171
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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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172
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Abstract
Alcohol-related diseases of the nervous system are caused by excessive exposures to alcohol, with or without co-existing nutritional or vitamin deficiencies. Toxic and metabolic effects of alcohol (ethanol) vary with brain region, age/developmental stage, dose, and duration of exposures. In the mature brain, heavy chronic or binge alcohol exposures can cause severe debilitating diseases of the central and peripheral nervous systems, and skeletal muscle. Most commonly, long-standing heavy alcohol abuse leads to disproportionate loss of cerebral white matter and impairments in executive function. The cerebellum (especially the vermis), cortical-limbic circuits, skeletal muscle, and peripheral nerves are also important targets of chronic alcohol-related metabolic injury and degeneration. Although all cell types within the nervous system are vulnerable to the toxic, metabolic, and degenerative effects of alcohol, astrocytes, oligodendrocytes, and synaptic terminals are major targets, accounting for the white matter atrophy, neural inflammation and toxicity, and impairments in synaptogenesis. Besides chronic degenerative neuropathology, alcoholics are predisposed to develop severe potentially life-threatening acute or subacute symmetrical hemorrhagic injury in the diencephalon and brainstem due to thiamine deficiency, which exerts toxic/metabolic effects on glia, myelin, and the microvasculature. Alcohol also has devastating neurotoxic and teratogenic effects on the developing brain in association with fetal alcohol spectrum disorder/fetal alcohol syndrome. Alcohol impairs function of neurons and glia, disrupting a broad array of functions including neuronal survival, cell migration, and glial cell (astrocytes and oligodendrocytes) differentiation. Further progress is needed to better understand the pathophysiology of this exposure-related constellation of nervous system diseases and better correlate the underlying pathology with in vivo imaging and biochemical lesions.
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173
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Glutamate transporters in the biology of malignant gliomas. Cell Mol Life Sci 2013; 71:1839-54. [PMID: 24281762 DOI: 10.1007/s00018-013-1521-z] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 10/22/2013] [Accepted: 11/11/2013] [Indexed: 12/11/2022]
Abstract
Malignant gliomas are relentless tumors that offer a dismal clinical prognosis. They develop many biological advantages that allow them to grow and survive in the unique environment of the brain. The glutamate transporters system x c (-) and excitatory amino acid transporters (EAAT) are emerging as key players in the biology and malignancy of these tumors. Gliomas manipulate glutamate transporter expression and function to alter glutamate homeostasis in the brain, which supports their own growth, invasion, and survival. As a consequence, malignant cells are able to quickly destroy and invade surrounding normal brain. Recent findings are painting a larger picture of these transporters in glioma biology, and as such are providing opportunities for clinical intervention for patients. This review will detail the current understanding of glutamate transporters in the biology of malignant gliomas and highlight some of the unique aspects of these tumors that make them so devastating and difficult to treat.
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174
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Novel treatment with neuroprotective and antiviral properties against a neuroinvasive human respiratory virus. J Virol 2013; 88:1548-63. [PMID: 24227863 DOI: 10.1128/jvi.02972-13] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Human coronaviruses (HCoVs) are recognized respiratory pathogens with neuroinvasive and neurotropic properties in mice and humans. HCoV strain OC43 (HCoV-OC43) can infect and persist in human neural cells and activate neuroinflammatory and neurodegenerative mechanisms, suggesting that it could be involved in neurological disease of unknown etiology in humans. Moreover, we have shown that HCoV-OC43 is neurovirulent in susceptible mice, causing encephalitis, and that a viral mutant with a single point mutation in the viral surface spike (S) protein induces a paralytic disease that involves glutamate excitotoxicity in susceptible mice. Herein, we show that glutamate recycling via the glial transporter 1 protein transporter and glutamine synthetase are central to the dysregulation of glutamate homeostasis and development of motor dysfunctions and paralytic disease in HCoV-OC43-infected mice. Moreover, memantine, an N-methyl-d-aspartate receptor antagonist widely used in the treatment of neurological diseases in humans, improved clinical scores related to paralytic disease and motor disabilities by partially restoring the physiological neurofilament phosphorylation state in virus-infected mice. Interestingly, memantine attenuated mortality rates and body weight loss and reduced HCoV-OC43 replication in the central nervous system in a dose-dependent manner. This novel action of memantine on viral replication strongly suggests that it could be used as an antiviral agent to directly limit viral replication while improving neurological symptoms in various neurological diseases with a viral involvement. Mutations in the surface spike (S) protein of human respiratory coronavirus OC43 appear after persistent infection of human cells of the central nervous system, a possible viral adaptation to this environment. Furthermore, a single amino acid change in the viral S protein modulated virus-induced neuropathology in mice from an encephalitis to a neuropathology characterized by flaccid paralysis, which involves glutamate excitotoxicity. We now show that memantine, a drug that is used for alleviating symptoms associated with neuropathology, such as Alzheimer's disease, can partially restore the physiological state of infected mice by limiting both neurodegeneration and viral replication. This suggests that memantine could be used as an antiviral agent while improving neurological symptoms in various neurological diseases with a viral involvement.
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175
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Mallimo EM, Kusnecov AW. The role of orphanin FQ/nociceptin in neuroplasticity: relationship to stress, anxiety and neuroinflammation. Front Cell Neurosci 2013; 7:173. [PMID: 24155687 PMCID: PMC3792366 DOI: 10.3389/fncel.2013.00173] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Accepted: 09/14/2013] [Indexed: 01/23/2023] Open
Abstract
The neuropeptide, orphanin FQ/nociceptin (OFQ/N or simply, nociceptin), is expressed in both neuronal and non-neuronal tissue, including the immune system. In the brain, OFQ/N has been investigated in relation to stress, anxiety, learning and memory, and addiction. More recently, it has also been found that OFQ/N influences glial cell functions, including oligodendrocytes, astrocytes, and microglial cells. However, this latter research is relatively small, but potentially important, when observations regarding the relationship of OFQ/N to stress and emotional functions is taken into consideration and integrated with the growing evidence for its involvement in cells that mediate inflammatory events. This review will first provide an overview and understanding of how OFQ/N has been implicated in the HPA axis response to stress, followed by an understanding of its influence on natural and learned anxiety-like behavior. What emerges from an examination of the literature is a neuropeptide that appears to counteract anxiogenic influences, but paradoxically, without attenuating HPA axis responses generated in response to stress. Studies utilized both central administration of OFQ/N, which was shown to activate the HPA axis, as well as antagonism of NOP-R, the OFQ/N receptor. In contrast, antagonist or transgenic OFQ/N or NOP-R knockout studies, showed augmentation of HPA axis responses to stress, suggesting that OFQ/N may be needed to control the magnitude of the HPA axis response to stress. Investigations of behavior in standard exploratory tests of anxiogenic behavior (eg., elevated plus maze) or learned fear responses have suggested that OFQ/N is needed to attenuate fear or anxiety-like behavior. However, some discrepant observations, in particular, those that involve appetitive behaviors, suggest a failure of NOP-R deletion to increase anxiety. However, it is also suggested that OFQ/N may operate in an anxiolytic manner when initial anxiogenic triggers (eg., the neuropeptide CRH) are initiated. Finally, the regulatory functions of OFQ/N in relation to emotion-related behaviors may serve to counteract potential neuroinflammatory events in the brain. This appears to be evident within the glial cell environment of the brain, since OFQ/N has been shown to reduce the production of proinflammatory cellular and cytokine events. Given that both OFQ/N and glial cells are activated in response to stress, it is possible that there is a possible convergence of these two systems that has important repercussions for behavior and neuroplasticity.
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Affiliation(s)
- Elyse M Mallimo
- Behavioral and Systems Neuroscience Program, Department of Psychology, Rutgers University New Brunswick, NJ, USA
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176
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Wang H, Yan H, Zhang S, Wei X, Zheng J, Li J. The GluN3A subunit exerts a neuroprotective effect in brain ischemia and the hypoxia process. ASN Neuro 2013; 5:231-42. [PMID: 23883441 PMCID: PMC3756525 DOI: 10.1042/an20130009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 07/21/2013] [Accepted: 07/24/2013] [Indexed: 02/04/2023] Open
Abstract
NMDARs (N-methyl-D-aspartate receptors) mediate the predominantly excitatory neurotransmission in the CNS (central nervous system). Excessive release of glutamate and overactivation of NMDARs during brain ischemia and the hypoxia process are causally linked to excitotoxicity and neuronal damage. GluN3 subunits, the third member of the NMDAR family with two isoforms, GluN3A and GluN3B, have been confirmed to display an inhibitory effect on NMDAR activity. However, the effect of GluN3 subunits in brain ischemia and hypoxia is not clearly understood. In the present study, the influence of ischemia and hypoxia on GluN3 subunit expression was observed by using the 2VO (two-vessel occlusion) rat brain ischemia model and cell OGD (oxygen and glucose deprivation) hypoxia model. It was found that GluN3A protein expression in rat hippocampus and the prefrontal cortex was increased quickly after brain ischemia and remained at a high level for at least 24 h. However, the expression of the GluN3B subunit was not remarkably changed in both the animal and cell models. After OGD exposure, rat hippocampal neurons with GluN3A subunit overexpression displayed more viability than the wild-type neurons. NG108-15 cells overexpressing GluN3A presented pronounced resistance to glutamate insult. Blocking the increase of intracellular Ca2+ concentration may underlie the neuroprotective mechanism of up-regulated GluN3A subunit. Suppressing the generation of hydroxyl radicals and NO (nitric oxide) is probably also involved in the neuroprotection.
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Key Words
- brain hypoxia and ischemia
- excitotoxicity
- glun3a
- n-methyl-d-aspartate receptor (nmdar)
- oxygen and glucose deprivation (ogd)
- 2vo, two-vessel occlusion
- cns, central nervous system
- dapi, 4′,6-diamidino-2-phenylindole
- fcm, flow cytometry
- gdna, genomic dna
- hbss, hanks’ balanced salt solution
- mtt, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2h-tetrazolium bromide
- nmdar, n-methyl-d-aspartate receptor
- no, nitric oxide
- ogd, oxygen and glucose deprivation
- pi, propidium iodide
- rt, reverse transcription
- s–d, sprague–dawley
- tbst, tbs containing 0.1% tween-20
- ttc, triphenyltetrazolium chloride
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Affiliation(s)
- Hui Wang
- Beijing Institute of Pharmacology and Toxicology, 27 Taiping Road, Beijing 100850, People's Republic of China
| | - Haitao Yan
- Beijing Institute of Pharmacology and Toxicology, 27 Taiping Road, Beijing 100850, People's Republic of China
| | - Shuzhuo Zhang
- Beijing Institute of Pharmacology and Toxicology, 27 Taiping Road, Beijing 100850, People's Republic of China
| | - Xiaoli Wei
- Beijing Institute of Pharmacology and Toxicology, 27 Taiping Road, Beijing 100850, People's Republic of China
| | - Jianquan Zheng
- Beijing Institute of Pharmacology and Toxicology, 27 Taiping Road, Beijing 100850, People's Republic of China
| | - Jin Li
- Beijing Institute of Pharmacology and Toxicology, 27 Taiping Road, Beijing 100850, People's Republic of China
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177
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Glutamate concentration in the medial prefrontal cortex predicts resting-state cortical-subcortical functional connectivity in humans. PLoS One 2013; 8:e60312. [PMID: 23573246 PMCID: PMC3616113 DOI: 10.1371/journal.pone.0060312] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 02/25/2013] [Indexed: 12/13/2022] Open
Abstract
Communication between cortical and subcortical regions is integral to a wide range of psychological processes and has been implicated in a number of psychiatric conditions. Studies in animals have provided insight into the biochemical and connectivity processes underlying such communication. However, to date no experiments that link these factors in humans in vivo have been carried out. To investigate the role of glutamate in individual differences in communication between the cortex--specifically the medial prefrontal cortex (mPFC)--and subcortical regions in humans, a combination of resting-state fMRI, DTI and MRS was performed. The subcortical target regions were the nucleus accumbens (NAc), dorsomedial thalamus (DMT), and periaqueductal grey (PAG). It was found that functional connectivity between the mPFC and each of the NAc and DMT was positively correlated with mPFC glutamate concentrations, whilst functional connectivity between the mPFC and PAG was negatively correlated with glutamate concentration. The correlations involving mPFC glutamate and FC between the mPFC and each of the DMT and PAG were mirrored by correlations with structural connectivity, providing evidence that the glutamatergic relationship may, in part, be due to direct connectivity. These results are in agreement with existing results from animal studies and may have relevance for MDD and schizophrenia.
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178
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Kopach O, Voitenko N. Extrasynaptic AMPA receptors in the dorsal horn: Evidence and functional significance. Brain Res Bull 2013. [DOI: 10.1016/j.brainresbull.2012.11.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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179
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Lai BQ, Wang JM, Duan JJ, Chen YF, Gu HY, Ling EA, Wu JL, Zeng YS. The integration of NSC-derived and host neural networks after rat spinal cord transection. Biomaterials 2013; 34:2888-901. [DOI: 10.1016/j.biomaterials.2012.12.046] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 12/30/2012] [Indexed: 12/27/2022]
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180
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Muetzel RL, Marjańska M, Collins PF, Becker MP, Valabrègue R, Auerbach EJ, Lim KO, Luciana M. In vivo 1H magnetic resonance spectroscopy in young-adult daily marijuana users. NEUROIMAGE-CLINICAL 2013; 2:581-589. [PMID: 23956957 PMCID: PMC3743264 DOI: 10.1016/j.nicl.2013.04.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
To date, there has been little work describing the neurochemical profile of young, heavy marijuana users. In this study, we examined 27 young-adult marijuana users and 26 healthy controls using single-voxel magnetic resonance spectroscopy on a 3 T scanner. The voxel was placed in the dorsal striatum, and estimated concentrations of glutamate + glutamine, myo-inositol, taurine + glucose, total choline and total N-acetylaspartate were examined between groups. There were no overall group effects, but two metabolites showed group by sex interactions. Lower levels of glutamate + glutamine (scaled to total creatine) were observed in female, but not male, marijuana users compared to controls. Higher levels of myo-inositol were observed in female users compared to female non-users and to males in both groups. Findings are discussed in relation to patterns of corticostriatal connectivity and function, in the context of marijuana abuse. The neurochemical profile of the basal ganglia was examined in young marijuana users. Glutamate/glutamine levels were lower in female users versus male users and controls. Higher myo-inositol levels were observed in female users as compared to other groups. Neurochemical impacts of marijuana may be particularly pronounced in females.
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Affiliation(s)
- Ryan L Muetzel
- Department of Psychology, University of Minnesota, Minneapolis, MN, USA
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181
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Lima AAM, Kvalsund MP, Souza PPED, Figueiredo ÍL, Soares AM, Mota RMS, Lima NL, Pinkerton RC, Patrick PP, Guerrant RL, Oriá RB. Zinc, vitamin A, and glutamine supplementation in Brazilian shantytown children at risk for diarrhea results in sex-specific improvements in verbal learning. Clinics (Sao Paulo) 2013; 68:351-8. [PMID: 23644855 PMCID: PMC3611743 DOI: 10.6061/clinics/2013(03)oa11] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Accepted: 11/19/2012] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE To identify the impact of supplemental zinc, vitamin A, and glutamine, alone or in combination, on long-term cognitive outcomes among Brazilian shantytown children with low median height-for-age z-scores. METHODS A randomized, double-blind, placebo-controlled trial was conducted in children aged three months to nine years old from the urban shanty compound community of Fortaleza, Brazil. Demographic and anthropometric information was assessed. The random treatment groups available for cognitive testing (total of 167 children) were: (1) placebo, n = 25; (2) glutamine, n = 23; (3) zinc, n = 18; (4) vitamin A, n = 19; (5) glutamine+zinc, n = 20; (6) glutamine+vitamin A, n = 21; (7) zinc+vitamin A, n = 23; and (8) glutamine+zinc+vitamin A, n = 18. Neuropsychological tests were administered for the cognitive domains of non-verbal intelligence and abstraction, psychomotor speed, verbal memory and recall ability, and semantic and phonetic verbal fluency. Statistical analyses were performed using SPSS, version 16.0. ClinicalTrials.gov: NCT00133406. RESULTS Girls receiving a combination of glutamine, zinc, and vitamin A had higher mean age-adjusted verbal learning scores than girls receiving only placebo (9.5 versus 6.4, p = 0.007) and girls receiving zinc+vitamin A (9.5 versus 6.5, p = 0.006). Similar group differences were not found between male study children. CONCLUSIONS The findings suggest that combination therapy offers a sex-specific advantage on tests of verbal learning, similar to that seen among female patients following traumatic brain injury.
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Affiliation(s)
- Aldo A M Lima
- Department of Physiology and Pharmacology, Clinical Research Unit and Institute of Biomedicine/Center for Global Health, School of Medicine, Federal University of Ceará, Fortaleza, CE, Brazil
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Blum K, Oscar-Berman M, Stuller E, Miller D, Giordano J, Morse S, McCormick L, Downs WB, Waite RL, Barh D, Neal D, Braverman ER, Lohmann R, Borsten J, Hauser M, Han D, Liu Y, Helman M, Simpatico T. Neurogenetics and Nutrigenomics of Neuro-Nutrient Therapy for Reward Deficiency Syndrome (RDS): Clinical Ramifications as a Function of Molecular Neurobiological Mechanisms. ACTA ACUST UNITED AC 2013; 3:139. [PMID: 23926462 DOI: 10.4172/2155-6105.1000139] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In accord with the new definition of addiction published by American Society of Addiction Medicine (ASAM) it is well-known that individuals who present to a treatment center involved in chemical dependency or other documented reward dependence behaviors have impaired brain reward circuitry. They have hypodopaminergic function due to genetic and/or environmental negative pressures upon the reward neuro-circuitry. This impairment leads to aberrant craving behavior and other behaviors such as Substance Use Disorder (SUD). Neurogenetic research in both animal and humans revealed that there is a well-defined cascade in the reward site of the brain that leads to normal dopamine release. This cascade has been termed the "Brain Reward Cascade" (BRC). Any impairment due to either genetics or environmental influences on this cascade will result in a reduced amount of dopamine release in the brain reward site. Manipulation of the BRC has been successfully achieved with neuro-nutrient therapy utilizing nutrigenomic principles. After over four decades of development, neuro-nutrient therapy has provided important clinical benefits when appropriately utilized. This is a review, with some illustrative case histories from a number of addiction professionals, of certain molecular neurobiological mechanisms which if ignored may lead to clinical complications.
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Affiliation(s)
- Kenneth Blum
- Department of Psychiatry, University of Florida, McKnight Brain Institute, Gainesville, Fl, 100183, USA ; Department of Nutrigenomic, LifeGen, Inc. San Diego, CA, 92101, USA ; Department of Holistic Medicine, G&G Holistic Addiction Treatment Center, North Miami Beach, Fl, 33162, USA ; Center for Genomics and Applied Gene Technology, Institute of Integrative Omics and applied Biotechnology (IIOAB), Nonakuri, Purbe Medinpur, West Bengal, 721172, India ; Path Foundation NY, New York, 10001, New York USA ; Malibu Beach Recovery Center, Malibu Beach, California, 9026, USA ; Dominion Diagnostics, North Kingstown Rhode Island, 02852, USA ; Global Integrated Services Unit University of Vermont Center for Clinical & Translational Science, College of Medicine, Burlington, VT, USA
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183
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Wang G, Qi Y, Gao L, Li G, Lv X, Jin Y. Effects of subacute exposure to 1,2-dichloroethane on mouse behavior and the related mechanisms. Hum Exp Toxicol 2012; 32:983-91. [DOI: 10.1177/0960327112470270] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The aim of this study was to explore the effects of subacute exposure to 1,2-dichloroethane (1,2-DCE) on mouse behavior and the related mechanisms focusing on alteration of oxidative stress and amino acid neurotransmitters in the brain. Mouse behavior was examined by open field test. Levels of nitric oxide (NO), malondialdehyde (MDA) and nonprotein sulfhydryl (NPSH) and activity of inducible nitric oxide synthase (iNOS) and superoxide dismutase (SOD) were determined by colorimetric method. Contents of glutamate (Glu), aspartate (Asp) and gamma-aminobutyric acid (GABA) were evaluated by high-performance liquid chromatography. Reduced locomotor and exploratory activities and increased anxiety were found in 0.45 and 0.9 g/m3 1,2-DCE-treated mice. In contrast, increased excitability was found in 0.225 g/m3 1,2-DCE-treated mice. Compensatory antioxidant status and increased NOS activity and NO level in the brain were found in 1,2-DCE-treated mice. Moreover, Glu contents in 1,2-DCE-treated mice and GABA contents in 0.9 g/m3 1,2-DCE-treated mice increased, whereas GABA contents in 0.225 g/m3 1,2-DCE-treated mice decreased significantly compared with control. Taken together, our results suggested that mouse behavior could be disturbed by subacute exposure to 1,2-DCE, and the changes of amino acid neurotransmitter in the brain might be related to the behavioral effects.
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Affiliation(s)
- G. Wang
- Department of Occupational and Environmental Health, School of Public Health, China Medical University, Shenyang, Liaoning, People’s Republic of China
| | - Y. Qi
- Department of Occupational and Environmental Health, School of Public Health, China Medical University, Shenyang, Liaoning, People’s Republic of China
| | - L. Gao
- Department of Occupational and Environmental Health, School of Public Health, China Medical University, Shenyang, Liaoning, People’s Republic of China
| | - G. Li
- Department of Occupational and Environmental Health, School of Public Health, China Medical University, Shenyang, Liaoning, People’s Republic of China
| | - X. Lv
- Department of Occupational and Environmental Health, School of Public Health, China Medical University, Shenyang, Liaoning, People’s Republic of China
| | - Y.P. Jin
- Department of Occupational and Environmental Health, School of Public Health, China Medical University, Shenyang, Liaoning, People’s Republic of China
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Eid T, Behar K, Dhaher R, Bumanglag AV, Lee TSW. Roles of glutamine synthetase inhibition in epilepsy. Neurochem Res 2012; 37:2339-50. [PMID: 22488332 PMCID: PMC3731630 DOI: 10.1007/s11064-012-0766-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 03/15/2012] [Accepted: 03/22/2012] [Indexed: 10/28/2022]
Abstract
Glutamine synthetase (GS, E.C. 6.3.1.2) is a ubiquitous and highly compartmentalized enzyme that is critically involved in several metabolic pathways in the brain, including the glutamine-glutamate-GABA cycle and detoxification of ammonia. GS is normally localized to the cytoplasm of most astrocytes, with elevated concentrations of the enzyme being present in perivascular endfeet and in processes close to excitatory synapses. Interestingly, an increasing number of studies have indicated that the expression, distribution, or activity of brain GS is altered in several brain disorders, including Alzheimer's disease, schizophrenia, depression, suicidality, and mesial temporal lobe epilepsy (MTLE). Although the metabolic and functional sequelae of brain GS perturbations are not fully understood, it is likely that a deficiency in brain GS will have a significant biological impact due to the critical metabolic role of the enzyme. Furthermore, it is possible that restoration of GS in astrocytes lacking the enzyme could constitute a novel and highly specific therapy for these disorders. The goals of this review are to summarize key features of mammalian GS under normal conditions, and discuss the consequences of GS deficiency in brain disorders, specifically MTLE.
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Affiliation(s)
- Tore Eid
- Department of Laboratory Medicine, Yale University School of Medicine, 330 Cedar Street, P.O. Box 208035, New Haven, CT 06520-8035, USA.
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Häberle J, Shahbeck N, Ibrahim K, Schmitt B, Scheer I, O'Gorman R, Chaudhry FA, Ben-Omran T. Glutamine supplementation in a child with inherited GS deficiency improves the clinical status and partially corrects the peripheral and central amino acid imbalance. Orphanet J Rare Dis 2012; 7:48. [PMID: 22830360 PMCID: PMC3495849 DOI: 10.1186/1750-1172-7-48] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Accepted: 07/06/2012] [Indexed: 11/10/2022] Open
Abstract
Glutamine synthetase (GS) is ubiquitously expressed in mammalian organisms and is a key enzyme in nitrogen metabolism. It is the only known enzyme capable of synthesising glutamine, an amino acid with many critical roles in the human organism. A defect in GLUL, encoding for GS, leads to congenital systemic glutamine deficiency and has been described in three patients with epileptic encephalopathy. There is no established treatment for this condition.Here, we describe a therapeutic trial consisting of enteral and parenteral glutamine supplementation in a four year old patient with GS deficiency. The patient received increasing doses of glutamine up to 1020 mg/kg/day. The effect of this glutamine supplementation was monitored clinically, biochemically, and by studies of the electroencephalogram (EEG) as well as by brain magnetic resonance imaging and spectroscopy.Treatment was well tolerated and clinical monitoring showed improved alertness. Concentrations of plasma glutamine normalized while levels in cerebrospinal fluid increased but remained below the lower reference range. The EEG showed clear improvement and spectroscopy revealed increasing concentrations of glutamine and glutamate in brain tissue. Concomitantly, there was no worsening of pre-existing chronic hyperammonemia.In conclusion, supplementation of glutamine is a safe therapeutic option for inherited GS deficiency since it corrects the peripheral biochemical phenotype and partially also improves the central biochemical phenotype. There was some clinical improvement but the patient had a long standing severe encephalopathy. Earlier supplementation with glutamine might have prevented some of the neuronal damage.
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Affiliation(s)
- Johannes Häberle
- Division of Metabolism and Children's Research Center, University Children's Hospital Zurich, Zurich, Switzerland.
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Visualization of glutamine transporter activities in living cells using genetically encoded glutamine sensors. PLoS One 2012; 7:e38591. [PMID: 22723868 PMCID: PMC3375291 DOI: 10.1371/journal.pone.0038591] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Accepted: 05/08/2012] [Indexed: 11/19/2022] Open
Abstract
Glutamine plays a central role in the metabolism of critical biological molecules such as amino acids, proteins, neurotransmitters, and glutathione. Since glutamine metabolism is regulated through multiple enzymes and transporters, the cellular glutamine concentration is expected to be temporally dynamic. Moreover, differentiation in glutamine metabolism between cell types in the same tissue (e.g. neuronal and glial cells) is often crucial for the proper function of the tissue as a whole, yet assessing cell-type specific activities of transporters and enzymes in such heterogenic tissue by physical fractionation is extremely challenging. Therefore, a method of reporting glutamine dynamics at the cellular level is highly desirable. Genetically encoded sensors can be targeted to a specific cell type, hence addressing this knowledge gap. Here we report the development of Föster Resonance Energy Transfer (FRET) glutamine sensors based on improved cyan and yellow fluorescent proteins, monomeric Teal Fluorescent Protein (mTFP)1 and venus. These sensors were found to be specific to glutamine, and stable to pH-changes within a physiological range. Using cos7 cells expressing the human glutamine transporter ASCT2 as a model, we demonstrate that the properties of the glutamine transporter can easily be analyzed with these sensors. The range of glutamine concentration change in a given cell can also be estimated using sensors with different affinities. Moreover, the mTFP1-venus FRET pair can be duplexed with another FRET pair, mAmetrine and tdTomato, opening up the possibility for real-time imaging of another molecule. These novel glutamine sensors will be useful tools to analyze specificities of glutamine metabolism at the single-cell level.
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