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Becker I, Wang-Eckhardt L, Lodder-Gadaczek J, Wang Y, Grünewald A, Eckhardt M. Mice deficient in the NAAG synthetase II gene Rimkla are impaired in a novel object recognition task. J Neurochem 2021; 157:2008-2023. [PMID: 33638175 DOI: 10.1111/jnc.15333] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 02/11/2021] [Accepted: 02/21/2021] [Indexed: 12/27/2022]
Abstract
N-acetylaspartylglutamate (NAAG) is an abundant neuropeptide in the mammalian nervous system, synthesized by two related NAAG synthetases I and II (NAAGS-I and -II) encoded by the genes Rimklb and Rimkla, respectively. NAAG plays a role in cognition and memory, according to studies using inhibitors of the NAAG hydrolase glutamate carboxypeptidase II that increase NAAG concentration. To examine consequences of reduced NAAG concentration, Rimkla-deficient (Rimkla-/- ) mice were generated. These mice exhibit normal NAAG level at birth, likely because of the intact Rimklb gene, but have significantly reduced NAAG levels in all brain regions in adulthood. In wild type mice NAAGS-II was most abundant in brainstem and spinal cord, as demonstrated using a new NAAGS-II antiserum. In the hippocampus, NAAGS-II was only detectable in neurons expressing parvalbumin, a marker of GABAergic interneurons. Apart from reduced open field activity, general behavior of adult (6 months old) Rimkla-/- mice examined in different tests (dark-light transition, optokinetic behavior, rotarod, and alternating T-maze) was not significantly altered. However, Rimkla-/- mice were impaired in a short-term novel object recognition test. This was also the case for mice lacking NAA synthase Nat8l, which are devoid of NAAG. Together with results from previous studies showing that inhibition of the NAAG degrading enzyme glutamate carboxypeptidase II is associated with a significant improvement in object recognition, these results suggest a direct involvement of NAAG synthesized by NAAGS-II in the memory consolidation underlying the novel object recognition task.
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Affiliation(s)
- Ivonne Becker
- Institute of Biochemistry and Molecular Biology, Medical Faculty, University of Bonn, Bonn, Germany
| | - Lihua Wang-Eckhardt
- Institute of Biochemistry and Molecular Biology, Medical Faculty, University of Bonn, Bonn, Germany
| | - Julia Lodder-Gadaczek
- Institute of Biochemistry and Molecular Biology, Medical Faculty, University of Bonn, Bonn, Germany
| | - Yong Wang
- Institute of Biochemistry and Molecular Biology, Medical Faculty, University of Bonn, Bonn, Germany
| | - Agathe Grünewald
- Institute of Biochemistry and Molecular Biology, Medical Faculty, University of Bonn, Bonn, Germany
| | - Matthias Eckhardt
- Institute of Biochemistry and Molecular Biology, Medical Faculty, University of Bonn, Bonn, Germany
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Emir UE, Sood J, Chiew M, Thomas MA, Lane SP. High-resolution metabolic mapping of the cerebellum using 2D zoom magnetic resonance spectroscopic imaging. Magn Reson Med 2020; 85:2349-2358. [PMID: 33283917 DOI: 10.1002/mrm.28614] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 10/03/2020] [Accepted: 11/04/2020] [Indexed: 12/20/2022]
Abstract
PURPOSE The human cerebellum plays an important role in the functional activity of the cerebrum, ranging from motor to cognitive systems given its relaying role between the spinal cord and cerebrum. The cerebellum poses many challenges to Magnetic Resonance Spectroscopic Imaging (MRSI) due to its caudal location, susceptibility to physiological artifacts, and partial volume artifacts resulting from its complex anatomical structure. Thus, in the present study, we propose a high-resolution MRSI acquisition scheme for the cerebellum. METHODS A zoom or reduced field of view (rFOV) metabolite-cycled MRSI acquisition at 3 Tesla, with a grid of 48 × 48, was developed to achieve a nominal resolution of 62.5 μL. Single-slice rFOV MRSI data were acquired from the cerebellum of 5 healthy subjects with a nominal resolution of 2.5 × 2.5 × 10 mm3 in 9.6 min. Spectra were quantified using the LCModel package. A spatially unbiased atlas template of the cerebellum was used to analyze metabolite distributions in the cerebellum. RESULTS The superior quality of the achieved spectra-enabled generation of high-resolution metabolic maps of total N-acetylaspartate, total Creatine (tCr), total Choline (tCho), glutamate+glutamine, and myo-inositol, with Cramér-Rao lower bounds below 50%. A template-based regions of interest (ROI) analysis resulted in spatially dependent metabolite distributions in 9 ROIs. The group-averaged high-resolution metabolite maps across subjects increased the contrast-to-noise ratio between cerebellum regions. CONCLUSION These findings indicate that very high-resolution metabolite probing of the cerebellum is feasible using rFOV or zoomed MRSI at 3 Tesla.
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Affiliation(s)
- Uzay E Emir
- School of Health Sciences, Purdue University, West Lafayette, Indiana, USA.,Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, USA
| | - Jaiyta Sood
- School of Health Sciences, Purdue University, West Lafayette, Indiana, USA
| | - Mark Chiew
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, United Kingdom
| | - Micheal Albert Thomas
- Department of Radiology, University of California Los Angeles, Los Angeles, California, USA
| | - Sean P Lane
- Department of Psychological Sciences, Purdue University, West Lafayette, Indiana, USA
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Moffett JR, Puthillathu N, Vengilote R, Jaworski DM, Namboodiri AM. Acetate Revisited: A Key Biomolecule at the Nexus of Metabolism, Epigenetics and Oncogenesis-Part 1: Acetyl-CoA, Acetogenesis and Acyl-CoA Short-Chain Synthetases. Front Physiol 2020; 11:580167. [PMID: 33281616 PMCID: PMC7689297 DOI: 10.3389/fphys.2020.580167] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Accepted: 09/23/2020] [Indexed: 12/19/2022] Open
Abstract
Acetate is a major end product of bacterial fermentation of fiber in the gut. Acetate, whether derived from the diet or from fermentation in the colon, has been implicated in a range of health benefits. Acetate is also generated in and released from various tissues including the intestine and liver, and is generated within all cells by deacetylation reactions. To be utilized, all acetate, regardless of the source, must be converted to acetyl coenzyme A (acetyl-CoA), which is carried out by enzymes known as acyl-CoA short-chain synthetases. Acyl-CoA short-chain synthetase-2 (ACSS2) is present in the cytosol and nuclei of many cell types, whereas ACSS1 is mitochondrial, with greatest expression in heart, skeletal muscle, and brown adipose tissue. In addition to acting to redistribute carbon systemically like a ketone body, acetate is becoming recognized as a cellular regulatory molecule with diverse functions beyond the formation of acetyl-CoA for energy derivation and lipogenesis. Acetate acts, in part, as a metabolic sensor linking nutrient balance and cellular stress responses with gene transcription and the regulation of protein function. ACSS2 is an important task-switching component of this sensory system wherein nutrient deprivation, hypoxia and other stressors shift ACSS2 from a lipogenic role in the cytoplasm to a regulatory role in the cell nucleus. Protein acetylation is a critical post-translational modification involved in regulating cell behavior, and alterations in protein acetylation status have been linked to multiple disease states, including cancer. Improving our fundamental understanding of the "acetylome" and how acetate is generated and utilized at the subcellular level in different cell types will provide much needed insight into normal and neoplastic cellular metabolism and the epigenetic regulation of phenotypic expression under different physiological stressors. This article is Part 1 of 2 - for Part 2 see doi: 10.3389/fphys.2020.580171.
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Affiliation(s)
- John R. Moffett
- Department of Anatomy, Physiology and Genetics, and Neuroscience Program, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Narayanan Puthillathu
- Department of Anatomy, Physiology and Genetics, and Neuroscience Program, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Ranjini Vengilote
- Department of Anatomy, Physiology and Genetics, and Neuroscience Program, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Diane M. Jaworski
- Department of Neurological Sciences, University of Vermont College of Medicine, Burlington, VT, United States
| | - Aryan M. Namboodiri
- Department of Anatomy, Physiology and Genetics, and Neuroscience Program, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
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Wittfoth C, Harzsch S, Wolff C, Sombke A. The "amphi"-brains of amphipods: new insights from the neuroanatomy of Parhyale hawaiensis (Dana, 1853). Front Zool 2019; 16:30. [PMID: 31372174 PMCID: PMC6660712 DOI: 10.1186/s12983-019-0330-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 07/15/2019] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Over the last years, the amphipod crustacean Parhyale hawaiensis has developed into an attractive marine animal model for evolutionary developmental studies that offers several advantages over existing experimental organisms. It is easy to rear in laboratory conditions with embryos available year-round and amenable to numerous kinds of embryological and functional genetic manipulations. However, beyond these developmental and genetic analyses, research on the architecture of its nervous system is fragmentary. In order to provide a first neuroanatomical atlas of the brain, we investigated P. hawaiensis using immunohistochemical labelings combined with laser-scanning microscopy, X-ray microcomputed tomography, histological sectioning and 3D reconstructions. RESULTS As in most amphipod crustaceans, the brain is dorsally bent out of the body axis with downward oriented lateral hemispheres of the protocerebrum. It comprises almost all prominent neuropils that are part of the suggested ground pattern of malacostracan crustaceans (except the lobula plate and projection neuron tract neuropil). Beyond a general uniformity of these neuropils, the brain of P. hawaiensis is characterized by an elaborated central complex and a modified lamina (first order visual neuropil), which displays a chambered appearance. In the light of a recent analysis on photoreceptor projections in P. hawaiensis, the observed architecture of the lamina corresponds to specialized photoreceptor terminals. Furthermore, in contrast to previous descriptions of amphipod brains, we suggest the presence of a poorly differentiated hemiellipsoid body and an inner chiasm and critically discuss these aspects. CONCLUSIONS Despite a general uniformity of amphipod brains, there is also a certain degree of variability in architecture and size of different neuropils, reflecting various ecologies and life styles of different species. In contrast to other amphipods, the brain of P. hawaiensis does not display any striking modifications or bias towards processing one particular sensory modality. Thus, we conclude that this brain represents a common type of an amphipod brain. Considering various established protocols for analyzing and manipulating P. hawaiensis, this organism is a suitable model to gain deeper understanding of brain anatomy e.g. by using connectome approaches, and this study can serve as first solid basis for following studies.
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Affiliation(s)
- Christin Wittfoth
- Department of Cytology and Evolutionary Biology, Zoological Institute and Museum, University of Greifswald, Soldmannstr. 23, 17487 Greifswald, Germany
| | - Steffen Harzsch
- Department of Cytology and Evolutionary Biology, Zoological Institute and Museum, University of Greifswald, Soldmannstr. 23, 17487 Greifswald, Germany
| | - Carsten Wolff
- Department of Biology, Comparative Zoology, Humboldt University Berlin, Philippstr. 13, 10115 Berlin, Germany
| | - Andy Sombke
- Department of Integrative Zoology, University of Vienna, Althanstr. 14, 1090 Vienna, Austria
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Hollinger KR, Alt J, Rais R, Kaplin AI, Slusher BS. The NAAG’ing Concerns of Modeling Human Alzheimer’s Disease in Mice. J Alzheimers Dis 2019; 68:939-945. [DOI: 10.3233/jad-181251] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Kristen R. Hollinger
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University, Baltimore, MD, USA
- Department of Neurology, Johns Hopkins University, Baltimore, MD, USA
- Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD, USA
| | - Jesse Alt
- Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD, USA
| | - Rana Rais
- Department of Neurology, Johns Hopkins University, Baltimore, MD, USA
- Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD, USA
| | - Adam I. Kaplin
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University, Baltimore, MD, USA
- Department of Neurology, Johns Hopkins University, Baltimore, MD, USA
| | - Barbara S. Slusher
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University, Baltimore, MD, USA
- Department of Neurology, Johns Hopkins University, Baltimore, MD, USA
- Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD, USA
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Soeiro-de-Souza MG, Otaduy MCG, Machado-Vieira R, Moreno RA, Nery FG, Leite C, Lafer B. Lithium-associated anterior cingulate neurometabolic profile in euthymic Bipolar I disorder: A 1H-MRS study. J Affect Disord 2018; 241:192-199. [PMID: 30130684 DOI: 10.1016/j.jad.2018.08.039] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 08/07/2018] [Accepted: 08/09/2018] [Indexed: 01/28/2023]
Abstract
OBJECTIVE In the treatment of Bipolar disorder (BD), achieving euthymia is highly complex and usually requires a combination of mood stabilizers. The mechanism of action in stabilizing mood has not been fully elucidated, but alterations in N-Acetylaspartate (NAA), Myo-Inositol (mI) and Choline (Cho) have been implicated. Proton magnetic resonance spectroscopy (1H-MRS) is the gold standard technique for measuring brain NAA, Cho and mI in vivo. The objective of this study was to investigate the association of lithium use in BD type I and brain levels of NAA, mI and Cho in the (anterior cingulate cortex) ACC. METHODS 129 BD type I subjects and 79 healthy controls (HC) were submitted to a 3-Tesla brain magnetic resonance imaging scan (1H-MRS) using a PRESS ACC single voxel (8cm3) sequence. RESULTS BD patients exhibited higher NAA and Cho levels compared to HC. Lithium prescription was associated with lower mI (combination + monotherapy) and higher NAA levels (monotherapy). CONCLUSION The results observed add to the knowledge about the mechanisms of action of mood stabilizers on brain metabolites during euthymia. Additionally, the observed decrease in mI levels associated with lithium monotherapy is an in vivo finding that supports the inositol-depletion hypothesis of lithium pharmacodynamics.
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Affiliation(s)
- Marcio Gerhardt Soeiro-de-Souza
- Mood Disorders Unit (GRUDA), Department and Institute of Psychiatry, University of Sao Paulo, Brazil; Genetics and Pharmacogenetics Unit (PROGENE), Department and Institute of Psychiatry, University of Sao Paulo, Brazil.
| | - Maria Concepcion Garcia Otaduy
- Laboratory of Magnetic Resonance LIM44, Department and Institute of Radiology, University of São Paulo (InRad-FMUSP), Brazil
| | | | - Ricardo Alberto Moreno
- Mood Disorders Unit (GRUDA), Department and Institute of Psychiatry, University of Sao Paulo, Brazil
| | - Fabiano G Nery
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati College of Medicine, USA
| | - Claudia Leite
- Laboratory of Magnetic Resonance LIM44, Department and Institute of Radiology, University of São Paulo (InRad-FMUSP), Brazil
| | - Beny Lafer
- Bipolar Disorders Program (PROMAN), Department and Institute of Psychiatry, University of São Paulo, Brazil
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Singh K, Trivedi R, Verma A, D'souza MM, Koundal S, Rana P, Baishya B, Khushu S. Altered metabolites of the rat hippocampus after mild and moderate traumatic brain injury - a combined in vivo and in vitro 1 H-MRS study. NMR IN BIOMEDICINE 2017; 30:e3764. [PMID: 28759166 DOI: 10.1002/nbm.3764] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 05/13/2017] [Accepted: 05/28/2017] [Indexed: 06/07/2023]
Abstract
Traumatic brain injury (TBI) has been shown to affect hippocampus-associated learning, memory and higher cognitive functions, which may be a consequence of metabolic alterations. Hippocampus-associated disorders may vary depending on the severity of injury [mild TBI (miTBI) and moderate TBI (moTBI)] and time since injury. The underlying hippocampal metabolic irregularities may provide an insight into the pathological process following TBI. In this study, in vivo and in vitro proton magnetic resonance spectroscopy (1 H-MRS) data were acquired from the hippocampus region of controls and TBI groups (miTBI and moTBI) at D0 (pre-injury), 4 h, Day 1 and Day 5 post-injury (PI). In vitro MRS results indicated trauma-induced changes in both miTBI and moTBI; however, in vivo MRS showed metabolic alterations in moTBI only. miTBI and moTBI showed elevated levels of osmolytes indicating injury-induced edema. Altered levels of citric acid cycle intermediates, glutamine/glutamate and amino acid metabolism indicated injury-induced aberrant bioenergetics, excitotoxicity and oxidative stress. An overall similar pattern of pathological process was observed in both miTBI and moTBI, with the distinction of depleted N-acetylaspartate levels (indicating neuronal loss) at 4 h and Day 1 and enhanced lactate production (indicating heightened energy depletion leading to the commencement of the anaerobic pathway) at Day 5 in moTBI. To the best of our knowledge, this is the first study to investigate the hippocampus metabolic profile in miTBI and moTBI simultaneously using in vivo and in vitro MRS.
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Affiliation(s)
- Kavita Singh
- NMR Research Centre, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Richa Trivedi
- NMR Research Centre, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Ajay Verma
- Centre for Biomedical Magnetic Resonance (CBMR), SGPGIMS Campus, Lucknow, Uttar Pradesh, India
| | - Maria M D'souza
- NMR Research Centre, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Sunil Koundal
- NMR Research Centre, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Poonam Rana
- NMR Research Centre, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Bikash Baishya
- Centre for Biomedical Magnetic Resonance (CBMR), SGPGIMS Campus, Lucknow, Uttar Pradesh, India
| | - Subash Khushu
- NMR Research Centre, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
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Activation of Group I and Group II Metabotropic Glutamate Receptors Causes LTD and LTP of Electrical Synapses in the Rat Thalamic Reticular Nucleus. J Neurosci 2015; 35:7616-25. [PMID: 25972185 DOI: 10.1523/jneurosci.3688-14.2015] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Compared with the extensive characterization of chemical synaptic plasticity, electrical synaptic plasticity remains poorly understood. Electrical synapses are strong and prevalent among the GABAergic neurons of the rodent thalamic reticular nucleus. Using paired whole-cell recordings, we show that activation of Group I metabotropic glutamate receptors (mGluRs) induces long-term depression of electrical synapses. Conversely, activation of the Group II mGluR, mGluR3, induces long-term potentiation of electrical synapses. By testing downstream targets, we show that modifications induced by both mGluR groups converge on the same signaling cascade--adenylyl cyclase to cAMP to protein kinase A--but with opposing effects. Furthermore, the magnitude of modification is inversely correlated to baseline coupling strength. Thus, electrical synapses, like their chemical counterparts, undergo both strengthening and weakening forms of plasticity, which should play a significant role in thalamocortical function.
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Abstract
Proton magnetic resonance spectroscopy (MRS) allows the noninvasive exploration of tissue metabolism in vivo, providing neurophysiological and neurochemical information. N-acetylaspartate (NAA) is generally considered to be a marker of neurons and axons, and many neurodegenerative disorders, including demyelinating disorders, exhibit a decrease in total NAA (tNAA). MRS in human hypomyelination disorders, such as Pelizaeus-Merzbacher disease (PMD), is characterized by normal to elevated tNAA, elevated myo-inositol and creatine (Cr), and normal to decreased choline (Cho). MRS in the thalamus of a hypomyelinating mouse model, a myelin synthesis-deficient (msd) mouse, a model of connatal PMD with mutation of the Plp1 gene, revealed increased tNAA and Cr and decreased Cho. That of a shiverer mouse with an autosomal recessive mutation of the Mbp gene showed decreased Cho with normal tNAA and Cr. Accordingly, the reduction of Cho on MRS might be a common marker for hypomyelinating disorders. tNAA concentrations range from normal to increased, probably depending upon the underlying pathology of oligodendrocytes. tNAA may be increased in hypomyelination with a reduced number of mature oligodendrocytes, such as PMD.
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Wei L, Xue R, Zhang P, Wu Y, Li X, Pei F. (1)H NMR-Based Metabolomics and Neurotoxicity Study of Cerebrum and Cerebellum in Rats Treated with Cinnabar, a Traditional Chinese Medicine. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2015; 19:490-8. [PMID: 26110755 DOI: 10.1089/omi.2015.0042] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Cinnabar, an important traditional Chinese mineral medicine, has been widely used as a Chinese patent medicine ingredient for sedative therapy. Nevertheless, the neurotoxic effects of cinnabar have also been noted. In this study, (1)H NMR-based metabolomics, combined with multivariate pattern recognition, were applied to investigate the neurotoxic effects of cinnabar after intragastrical administration (dosed at 2 and 5 g/kg body weight) on male Wistar rats. The metabolite variations induced by cinnabar were characterized by increased levels of glutamate, glutamine, myo-inositol, and choline, as well as decreased levels of GABA, taurine, NAA, and NAAG in tissue extracts of the cerebellum and cerebrum. These findings suggested that cinnabar induced glutamate excitotoxicity, neuronal cell loss, osmotic state changes, membrane fluidity disruption, and oxidative injury in the brain. We also show here that there is a dose- and time-dependent neurotoxicity of cinnabar, and that cerebellum was more sensitive to cinnabar induction than cerebrum. This work illustrates the utility and reliability of (1)H NMR-based metabolomics approach for examining the potential neurotoxic effects of cinnabar and other traditional Chinese medicines.
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Affiliation(s)
- Lai Wei
- Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun, People's Republic of China
| | - Rong Xue
- Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun, People's Republic of China
| | - Panpan Zhang
- Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun, People's Republic of China
| | - Yijie Wu
- Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun, People's Republic of China
| | - Xiaojing Li
- Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun, People's Republic of China
| | - Fengkui Pei
- Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun, People's Republic of China
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Nordengen K, Heuser C, Rinholm JE, Matalon R, Gundersen V. Localisation of N-acetylaspartate in oligodendrocytes/myelin. Brain Struct Funct 2013; 220:899-917. [PMID: 24379086 DOI: 10.1007/s00429-013-0691-7] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 12/14/2013] [Indexed: 11/29/2022]
Abstract
The role of N-acetylaspartate in the brain is unclear. Here we used specific antibodies against N-acetylaspartate and immunocytochemistry of carbodiimide-fixed adult rodent brain to show that, besides staining of neuronal cell bodies in the grey matter, N-acetylaspartate labelling was present in oligodendrocytes/myelin in white matter tracts. Immunoelectron microscopy of the rat hippocampus showed that N-acetylaspartate was concentrated in the myelin. Also neuronal cell bodies and axons contained significant amounts of N-acetylaspartate, while synaptic elements and astrocytes were low in N-acetylaspartate. Mitochondria in axons and neuronal cell bodies contained higher levels of N-acetylaspartate compared to the cytosol, compatible with synthesis of N-acetylaspartate in mitochondria. In aspartoacylase knockout mice, in which catabolism of N-acetylaspartate is blocked, the levels of N-acetylaspartate were largely increased in oligodendrocytes/myelin. In these mice, the highest myelin concentration of N-acetylaspartate was found in the cerebellum, a region showing overt dysmyelination. In organotypic cortical slice cultures there was no evidence for N-acetylaspartate-induced myelin toxicity, supporting the notion that myelin damage is induced by the lack of N-acetylaspartate for lipid production. Our findings also implicate that N-acetylaspartate signals on magnetic resonance spectroscopy reflect not only vital neurons but also vital oligodendrocytes/myelin.
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Affiliation(s)
- Kaja Nordengen
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, PO Box 1105, 0317, Oslo, Norway
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Takanashi JI, Nitta N, Iwasaki N, Saito S, Tanaka R, Barkovich AJ, Aoki I. Neurochemistry in shiverer mouse depicted on MR spectroscopy. J Magn Reson Imaging 2013; 39:1550-7. [DOI: 10.1002/jmri.24306] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 06/18/2013] [Indexed: 11/11/2022] Open
Affiliation(s)
- Jun-ichi Takanashi
- Molecular Imaging Center; National Institute of Radiological Sciences; Chiba Japan
- Department of Pediatrics; Kameda Medical Center; Kamogawa Japan
- Department of Radiology; Toho University Sakura Medical Center; Sakura Japan
| | - Nobuhiro Nitta
- Molecular Imaging Center; National Institute of Radiological Sciences; Chiba Japan
| | - Nobuaki Iwasaki
- Department of Pediatrics; Ibaraki Prefectural University of Health Sciences; Amimachi Japan
| | - Shigeyoshi Saito
- Department of Medical Physics and Engineering; Graduate School of Medicine; Osaka University; Suita Japan
| | - Ryuta Tanaka
- Department of Pediatrics; University of Tsukuba; Tsukuba Japan
| | - A. James Barkovich
- Department of Radiology and Biomedical Imaging; University of California San Francisco; California USA
| | - Ichio Aoki
- Molecular Imaging Center; National Institute of Radiological Sciences; Chiba Japan
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Abstract
NAAG (N-acetylaspartylglutamate) is an abundant neuropeptide in the vertebrate nervous system. It is released from synaptic terminals in a calcium-dependent manner and has been shown to act as an agonist at the type II metabotropic glutamate receptor mGluR3. It has been proposed that NAAG may also be released from axons. So far, however, it has remained unclear how NAAG is transported into synaptic or other vesicles before it is secreted. In the present study, we demonstrate that uptake of NAAG and the related peptide NAAG2 (N-acetylaspartylglutamylglutamate) into vesicles depends on the sialic acid transporter sialin (SLC17A5). This was demonstrated using cell lines expressing a cell surface variant of sialin and by functional reconstitution of sialin in liposomes. NAAG uptake into sialin-containing proteoliposomes was detectable in the presence of an active H+-ATPase or valinomycin, indicating that transport is driven by membrane potential rather than H+ gradient. We also show that sialin is most probably the major and possibly only vesicular transporter for NAAG and NAAG2, because ATP-dependent transport of both peptides was not detectable in vesicles isolated from sialin-deficient mice.
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Region- and age-dependent alterations of glial-neuronal metabolic interactions correlate with CNS pathology in a mouse model of globoid cell leukodystrophy. J Cereb Blood Flow Metab 2013; 33:1127-37. [PMID: 23611871 PMCID: PMC3705444 DOI: 10.1038/jcbfm.2013.64] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 02/27/2013] [Accepted: 03/27/2013] [Indexed: 01/20/2023]
Abstract
Globoid cell leukodystrophy (GLD) or Krabbe disease is a lysosomal storage disorder caused by genetic defects in the expression and activity of galactosylceramidase, a key enzyme in the catabolism of myelin-enriched sphingolipids. While there are several histologic, biochemical, and functional studies on GLD, correlations between morphologic and biochemical alterations in central nervous system (CNS) tissues during disease progression are lacking. Here, we combined immunohistochemistry and metabolic analysis using (1)H and (13)C magnetic resonance (MR) spectra of spinal cord, cerebellum, and forebrain to investigate glial-neuronal metabolic interactions and dysfunction in a GLD murine model that recapitulates the human pathology. In order to assess the temporal- and region-dependent disease progression and the potential metabolic correlates, we investigated CNS tissues at mildly symptomatic and fully symptomatic stages of the disease. When compared with age-matched controls, GLD mice showed glucose hypometabolism, alterations in neurotransmitter content, N-acetylaspartate, N-acetylaspartylglutamate, and osmolytes levels. Notably, age- and region-dependent patterns of metabolic disturbances were in close agreement with the progression of astrogliosis, microglia activation, apoptosis, and neurodegeneration. We suggest that MR spectroscopy could be used in vivo to monitor disease progression, as well as ex vivo and in vivo to provide criteria for the outcome of experimental therapies.
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Hajek T, Bauer M, Pfennig A, Cullis J, Ploch J, O’Donovan C, Bohner G, Klingebiel R, Young LT, MacQueen GM, Alda M. Large positive effect of lithium on prefrontal cortex N-acetylaspartate in patients with bipolar disorder: 2-centre study. J Psychiatry Neurosci 2012; 37:185-92. [PMID: 22353634 PMCID: PMC3341410 DOI: 10.1503/jpn.110097] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
BACKGROUND Neuroprotective effects of lithium (Li) have been well documented in tissue cultures and animal models, whereas human data continue to be limited. Previous studies investigating the association between Li treatment and brain N-acetylaspartate (NAA), a putative neuronal marker, showed mixed results because of methodological heterogeneity. METHODS To investigate the effects of Li on prefrontal cortex NAA levels, we compared patients with bipolar disorder from specialized Li clinics in Berlin and Halifax with at least 2 years of ongoing Li treatment (Li group), patients with lifetime Li exposure of less than 3 months more than 2 years ago (non-Li group) and healthy controls. Participants in both patient groups had at least 10 years of illness and 5 episodes. We measured left prefrontal NAA levels using 1.5-T magnetic resonance spectroscopy. RESULTS We enrolled 27 participants in the Li, 16 in the non-Li and 21 in the healthy control groups. The non-Li group had lower prefrontal NAA levels than the Li group (t41 = -3.44, corrected p < 0.01) or control participants (t35 = -2.91, corrected p < 0.05), who did not differ from the Li group (t46 = -0.14, p = 0.89). The same pattern of prefrontal NAA differences was replicated in both sites. In addition, there was a negative correlation between prefrontal NAA and duration of illness in the non-Li group (r = -0.60, p = 0.019) but not in the Li group (r = 0.07, p = 0.74). LIMITATIONS Study limitations include the crosssectional design and exposure to other medications. CONCLUSION Whereas patients with bipolar disorder, substantial illness burden and limited lifetime Li exposure had significantly lower prefrontal NAA levels than controls, Li-treated patients with similar illness burden showed prefrontal NAA levels comparable to those of healthy controls. These findings provide indirect support for neuroprotective effects of Li and for negative effects of illness burden on prefrontal NAA levels in patients with bipolar disorder.
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Affiliation(s)
- Tomas Hajek
- Department of Psychiatry, Dalhousie University, Halifax, NS.
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Takanashi JI, Saito S, Aoki I, Barkovich AJ, Ito Y, Inoue K. Increased N-acetylaspartate in model mouse of pelizaeus-merzbacher disease. J Magn Reson Imaging 2011; 35:418-25. [DOI: 10.1002/jmri.22817] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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17
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Moffett JR, Arun P, Ariyannur PS, Garbern JY, Jacobowitz DM, Namboodiri AMA. Extensive aspartoacylase expression in the rat central nervous system. Glia 2011; 59:1414-34. [PMID: 21598311 PMCID: PMC3143213 DOI: 10.1002/glia.21186] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 04/14/2011] [Indexed: 11/08/2022]
Abstract
Aspartoacylase (ASPA) catalyzes deacetylation of N-acetylaspartate (NAA) to generate acetate and aspartate. Mutations in the gene for ASPA lead to reduced acetate availability in the CNS during development resulting in the fatal leukodystrophy Canavan disease. Highly specific polyclonal antibodies to ASPA were used to examine CNS expression in adult rats. In white matter, ASPA expression was associated with oligodendrocyte cell bodies, nuclei, and some processes, but showed a dissimilar distribution pattern to myelin basic protein and oligodendrocyte specific protein. Microglia expressed ASPA in all CNS regions examined, as did epiplexus cells of the choroid plexus. Pial and ependymal cells and some endothelial cells were ASPA positive, as were unidentified cellular nuclei throughout the CNS. Astrocytes did not express ASPA in their cytoplasm. In some fiber pathways and nerves, particularly in the brainstem and spinal cord, the axoplasm of many neuronal fibers expressed ASPA, as did some neurons. Acetyl coenzyme A synthase immunoreactivity was also observed in the axoplasm of many of the same fiber pathways and nerves. All ASPA-immunoreactive elements were unstained in brain sections from tremor rats, an ASPA-null mutant. The strong expression of ASPA in oligodendrocyte cell bodies is consistent with a lipogenic role in myelination. Strong ASPA expression in cell nuclei is consistent with a role for NAA-derived acetate in nuclear acetylation reactions, including histone acetylation. Expression of ASPA in microglia may indicate a role in lipid synthesis in these cells, whereas expression in axons suggests that some neurons can both synthesize and catabolize NAA.
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Affiliation(s)
- John R Moffett
- Department of Anatomy, Physiology & Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, USA.
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Lodder-Gadaczek J, Becker I, Gieselmann V, Wang-Eckhardt L, Eckhardt M. N-acetylaspartylglutamate synthetase II synthesizes N-acetylaspartylglutamylglutamate. J Biol Chem 2011; 286:16693-706. [PMID: 21454531 DOI: 10.1074/jbc.m111.230136] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
N-Acetylaspartylglutamate (NAAG) is found at high concentrations in the vertebrate nervous system. NAAG is an agonist at group II metabotropic glutamate receptors. In addition to its role as a neuropeptide, a number of functions have been proposed for NAAG, including a role as a non-excitotoxic transport form of glutamate and a molecular water pump. We recently identified a NAAG synthetase (now renamed NAAG synthetase I, NAAGS-I), encoded by the ribosomal modification protein rimK-like family member B (Rimklb) gene, as a member of the ATP-grasp protein family. We show here that a structurally related protein, encoded by the ribosomal modification protein rimK-like family member A (Rimkla) gene, is another NAAG synthetase (NAAGS-II), which in addition, synthesizes the N-acetylated tripeptide N-acetylaspartylglutamylglutamate (NAAG(2)). In contrast, NAAG(2) synthetase activity was undetectable in cells expressing NAAGS-I. Furthermore, we demonstrate by mass spectrometry the presence of NAAG(2) in murine brain tissue and sciatic nerves. The highest concentrations of both, NAAG(2) and NAAG, were found in sciatic nerves, spinal cord, and the brain stem, in accordance with the expression level of NAAGS-II. To our knowledge the presence of NAAG(2) in the vertebrate nervous system has not been described before. The physiological role of NAAG(2), e.g. whether it acts as a neurotransmitter, remains to be determined.
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Affiliation(s)
- Julia Lodder-Gadaczek
- Institute of Biochemistry and Molecular Biology, University of Bonn, D-53115 Bonn, Germany
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19
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Collard F, Stroobant V, Lamosa P, Kapanda CN, Lambert DM, Muccioli GG, Poupaert JH, Opperdoes F, Van Schaftingen E. Molecular identification of N-acetylaspartylglutamate synthase and beta-citrylglutamate synthase. J Biol Chem 2010; 285:29826-33. [PMID: 20657015 DOI: 10.1074/jbc.m110.152629] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The purpose of the present work was to determine the identity of the enzymes that synthesize N-acetylaspartylglutamate (NAAG), the most abundant dipeptide present in vertebrate central nervous system (CNS), and β-citrylglutamate, a structural analogue of NAAG present in testis and immature brain. Previous evidence suggests that NAAG is not synthesized on ribosomes but presumably is synthesized by a ligase. As attempts to detect this ligase in brain extracts failed, we searched the mammalian genomes for putative enzymes that could catalyze this type of reaction. Mammalian genomes were found to encode two putative ligases homologous to Escherichia coli RIMK, which ligates glutamates to the C terminus of ribosomal protein S6. One of them, named RIMKLA, is almost exclusively expressed in the CNS, whereas RIMKLB, which shares 65% sequence identity with RIMKLA, is expressed in CNS and testis. Both proteins were expressed in bacteria or HEK293T cells and purified. RIMKLA catalyzed the ATP-dependent synthesis of N-acetylaspartylglutamate from N-acetylaspartate and l-glutamate. RIMKLB catalyzed this reaction as well as the synthesis of β-citrylglutamate. The nature of the reaction products was confirmed by mass spectrometry and NMR. RIMKLA was shown to produce stoichiometric amounts of NAAG and ADP, in agreement with its belonging to the ATP-grasp family of ligases. The molecular identification of these two enzymes will facilitate progress in the understanding of the function of NAAG and β-citrylglutamate.
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Affiliation(s)
- François Collard
- Laboratory of Physiological Chemistry, de Duve Institute and Université Catholique de Louvain, Avenue Hippocrate 75, B-1200 Brussels, Belgium
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Madhavarao CN, Arun P, Anikster Y, Mog SR, Staretz-Chacham O, Moffett JR, Grunberg NE, Gahl WA, Namboodiri AMA. Glyceryl triacetate for Canavan disease: a low-dose trial in infants and evaluation of a higher dose for toxicity in the tremor rat model. J Inherit Metab Dis 2009; 32:640. [PMID: 19685155 DOI: 10.1007/s10545-009-1155-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Revised: 06/24/2009] [Accepted: 06/25/2009] [Indexed: 12/24/2022]
Abstract
Canavan disease (CD) is a fatal dysmyelinating genetic disorder associated with aspartoacylase deficiency, resulting in decreased brain acetate levels and reduced myelin lipid synthesis in the developing brain. Here we tested tolerability of a potent acetate precursor, glyceryl triacetate (GTA), at low doses in two infants diagnosed with CD, aged 8 and 13 months. Much higher doses of GTA were evaluated for toxicity in the tremor rat model of CD. GTA was given orally to the infants for up to 4.5 and 6 months, starting at 25 mg/kg twice daily, doubling the dose weekly until a maximum of 250 mg/kg reached. Wild-type and tremor rat pups were given GTA orally twice daily, initially at a dose of 4.2 g/kg from postnatal days 7 through 14, and at 5.8 g/kg from day 15 through 23, and thereafter in food (7.5%) and water (5%). At the end of the trial (approximately 90 to 120 days) sera and tissues from rats were analysed for changes in blood chemistry and histopathology. GTA treatment caused no detectable toxicity and the patients showed no deterioration in clinical status. In the high-dose animal studies, no significant differences in the mean blood chemistry values occurred between treated and untreated groups, and no lesions indicating toxicity were detectable in any of the tissues examined. Lack of GTA toxicity in two CD patients in low-dose trials, as well as in high-dose animal studies, suggests that higher, effective dose studies in human CD patients are warranted.
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Affiliation(s)
- C N Madhavarao
- Department of Anatomy, Physiology and Genetics, Program in Neuroscience and Program in Molecular and Cell Biology, USUHS, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA
| | - P Arun
- Department of Anatomy, Physiology and Genetics, Program in Neuroscience and Program in Molecular and Cell Biology, USUHS, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA
| | - Y Anikster
- Metabolic Disease Unit, Safra Children Hospital, Sheba Medical Center, Tel-Hashomer, and Sackler Medical School, Tel Aviv University, Tel Aviv, Israel
| | - S R Mog
- Division of Comparative Pathology, AFRRI, Bethesda, MD, USA
| | | | - J R Moffett
- Department of Anatomy, Physiology and Genetics, Program in Neuroscience and Program in Molecular and Cell Biology, USUHS, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA
| | - N E Grunberg
- Department of Medical and Clinical Psychology, Program in Neuroscience, USUHS, Bethesda, MD, USA
| | - W A Gahl
- Medical Genetics Branch, NHGRI, NIH, Bethesda, MD, USA
| | - A M A Namboodiri
- Department of Anatomy, Physiology and Genetics, Program in Neuroscience and Program in Molecular and Cell Biology, USUHS, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA.
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Ferreira PEMS, Palmini A, Bau CHD, Grevet EH, Hoefel JR, Rohde LA, Anés M, Ferreira EE, Belmonte-de-Abreu P. Differentiating attention-deficit/hyperactivity disorder inattentive and combined types: a (1)H-magnetic resonance spectroscopy study of fronto-striato-thalamic regions. J Neural Transm (Vienna) 2009; 116:623-9. [PMID: 19399368 DOI: 10.1007/s00702-009-0191-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2008] [Accepted: 01/28/2009] [Indexed: 11/30/2022]
Abstract
Despite the implication of fronto-striatal circuits in attention-deficit/hyperactivity disorder (ADHD), there is a lack of information on the role of these regions, especially the thalamus, in the heterogeneity of ADHD. We assessed the (1)H-magnetic resonance spectroscopy profile in ventromedial prefrontal cortex (VMPFC)-thalamic-striatal regions bilaterally in three groups of subjects (age range 18-24 years old): ADHD inattentive type (ADHD-I; n = 9), ADHD combined type (ADHD-C; n = 10) and non-ADHD controls (n = 12). The peaks of N-acetylaspartate, Choline (Cho), myo-inositol (mI), creatine (Cr) and glutamate-glutamine-GABA (Glx) to Cr were calculated. Subjects with ADHD-C showed lower mI/Cr ratio in the right VMPFC than controls, higher Cho/Cr ratio in the left thalamus-pulvinar than the ADHD-I group and higher Glx/Cr ratio in left putamen than individuals with ADHD-I and controls. This metabolic profile suggests a disruption of fronto-striato-thalamic structures in the ADHD-C as a result of lower neuronal energetic metabolism.
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Affiliation(s)
- Pedro E M S Ferreira
- Graduate Program in Neurosciences, and Neurology and Psychiatry Services, Serviço de Psiquiatria do Hospital São Lucas da PUCRS, Pontifícia Universidade Católica do Rio Grande do Sul (HSL-PUCRS), Rio Grande do Sul, Brazil.
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22
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Baslow MH, Guilfoyle DN. Are Astrocytes the Missing Link Between Lack of Brain Aspartoacylase Activity and the Spongiform Leukodystrophy in Canavan Disease? Neurochem Res 2009; 34:1523-34. [DOI: 10.1007/s11064-009-9958-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2008] [Accepted: 03/09/2009] [Indexed: 10/21/2022]
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23
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A novel key–lock mechanism for inactivating amino acid neurotransmitters during transit across extracellular space. Amino Acids 2009; 38:51-5. [DOI: 10.1007/s00726-009-0232-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Accepted: 01/05/2009] [Indexed: 10/21/2022]
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Arun P, Madhavarao CN, Moffett JR, Namboodiri AMA. Antipsychotic drugs increase N-acetylaspartate and N-acetylaspartylglutamate in SH-SY5Y human neuroblastoma cells. J Neurochem 2008; 106:1669-80. [PMID: 18631215 DOI: 10.1111/j.1471-4159.2008.05524.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
N-Acetylaspartate (NAA) and N-acetylaspartylglutamate (NAAG) are related neuronal metabolites associated with the diagnosis and treatment of schizophrenia. NAA is a valuable marker of neuronal viability in magnetic resonance spectroscopy, a technique which has consistently shown NAA levels to be modestly decreased in the brains of schizophrenia patients. However, there are conflicting reports on the changes in brain NAA levels after treatment with antipsychotic drugs, which exert their therapeutic effects in part by blocking dopamine D(2) receptors. NAAG is reported to be an agonist of the metabotropic glutamate 2/3 receptor, which is linked to neurotransmitter release modulation, including glutamate release. Alterations in NAAG metabolism have been implicated in the development of schizophrenia possibly via dysregulation of glutamate neurotransmission. In the present study we have used high performance liquid chromatography to determine the effects of the antipsychotic drugs haloperidol and clozapine on NAA and NAAG levels in SH-SY5Y human neuroblastoma cells, a model system used to test the responses of dopaminergic neurons in vitro. The results indicate that the antipsychotic drugs haloperidol and clozapine increase both NAA and NAAG levels in SH-SY5Y cells in a dose and time dependant manner, providing evidence that NAA and NAAG metabolism in neurons is responsive to antipsychotic drug treatment.
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Affiliation(s)
- Peethambaran Arun
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
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25
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Pacheco Otalora LF, Moffett JR, Garrido-Sanabria ER. Selective vulnerability of hippocampal NAAGergic neurons in experimental temporal lobe epilepsy. Brain Res 2007; 1144:219-30. [PMID: 17346683 DOI: 10.1016/j.brainres.2007.01.112] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2006] [Revised: 01/24/2007] [Accepted: 01/24/2007] [Indexed: 11/22/2022]
Abstract
The dipeptide N-acetylaspartylglutamate (NAAG) has been recently implicated in numerous neurological disorders. NAAG binds and stimulates group II metabotropic glutamate receptors producing a down-modulation of synaptic glutamate release. In the present immunohistochemical study, we compare the distribution of NAAG-containing (NAAGergic) neurons between the hippocampus of control and chronic epileptic rats obtained with the pilocarpine model of temporal lobe epilepsy. In the hippocampal formation, NAAGergic neurons comprise a subpopulation of GABAergic neurons. Examination by light microscopy revealed a significant reduction of NAAG-immunoreactive neurons in CA3 stratum oriens (35.8%) and CA1 stratum oriens (78.87%), stratum pyramidale (40%), and stratum radiatum (56.6%). Similar loss of NAAGergic neurons was observed in the subiculum characterized by 71.82% and 77.53% reduction in the stratum oriens and radiatum, respectively, when compared with controls. NAAGergic neurons in CA2 and dentate gyrus were apparently resistant to seizure-related cell loss but appeared more complex and exhibited numerous NAAG-positive puncta. Our findings indicate a selective vulnerability of NAAGergic neurons in temporal lobe epilepsy.
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Affiliation(s)
- Luis F Pacheco Otalora
- Department of Biological Sciences at the University of Texas at Brownsville/Texas Southmost College, 80 Fort Brown, Brownsville, TX 78520, USA
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