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Imaging patients with psychosis and a mouse model establishes a spreading pattern of hippocampal dysfunction and implicates glutamate as a driver. Neuron 2013; 78:81-93. [PMID: 23583108 DOI: 10.1016/j.neuron.2013.02.011] [Citation(s) in RCA: 390] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/07/2013] [Indexed: 11/22/2022]
Abstract
VIDEO ABSTRACT The hippocampus in schizophrenia is characterized by both hypermetabolism and reduced size. It remains unknown whether these abnormalities are mechanistically linked. Here we addressed this question by using MRI tools that can map hippocampal metabolism and structure in patients and mouse models. In at-risk patients, hypermetabolism was found to begin in CA1 and spread to the subiculum after psychosis onset. CA1 hypermetabolism at baseline predicted hippocampal atrophy, which occurred during progression to psychosis, most prominently in similar regions. Next, we used ketamine to model conditions of acute psychosis in mice. Acute ketamine reproduced a similar regional pattern of hypermetabolism, while repeated exposure shifted the hippocampus to a hypermetabolic basal state with concurrent atrophy and pathology in parvalbumin-expressing interneurons. Parallel in vivo experiments using the glutamate-reducing drug LY379268 and direct measurements of extracellular glutamate showed that glutamate drives both neuroimaging abnormalities. These findings show that hippocampal hypermetabolism leads to atrophy in psychotic disorder and suggest glutamate as a pathogenic driver.
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Lewandowski NM, Bordelon Y, Brickman AM, Angulo S, Khan U, Muraskin J, Griffith EY, Wasserman P, Menalled L, Vonsattel JP, Marder K, Small SA, Moreno H. Regional vulnerability in Huntington's disease: fMRI-guided molecular analysis in patients and a mouse model of disease. Neurobiol Dis 2013; 52:84-93. [PMID: 23220414 PMCID: PMC4435974 DOI: 10.1016/j.nbd.2012.11.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 10/20/2012] [Accepted: 11/22/2012] [Indexed: 12/23/2022] Open
Abstract
Although the huntingtin gene is expressed in brain throughout life, phenotypically Huntington's disease (HD) begins only in midlife and affects specific brain regions. Here, to investigate regional vulnerability in the disease, we used functional magnetic resonance imaging (fMRI) to translationally link studies in patients with a mouse model of disease. Using fMRI, we mapped cerebral blood volume (CBV) in three groups: HD patients, symptom-free carriers of the huntingtin genetic mutation, and age-matched controls. In contrast to a region in the anterior caudate, in which dysfunction was linked to genotype independent of phenotype, a region in the posterior body of the caudate was differentially associated with disease phenotype. Guided by these observations, we harvested regions from the anterior and posterior body of the caudate in postmortem control and HD human brain tissue. Gene-expression profiling identified two molecules whose expression levels were most strongly correlated with regional vulnerability - protein phosphatase 1 regulatory subunit 7 (PPP1R7) and Wnt inhibitory factor-1 (WIF-1). To verify and potentially extend these findings, we turned to the YAC128 (C57BL/6J) HD transgenic mice. By fMRI we longitudinally mapped CBV in transgenic and wildtype (WT) mice, and over time, abnormally low fMRI signal emerged selectively in the dorsal striatum. A relatively unaffected brain region, primary somatosensory cortex (S1), was used as a control. Both dorsal striatum and S1 were harvested from transgenic and WT mice and molecular analysis confirmed that PPP1R7 deficiency was strongly correlated with the phenotype. Together, converging findings in human HD patients and this HD mouse model suggest a functional pattern of caudate vulnerability and that variation in expression levels of herein identified molecules correlate with this pattern of vulnerability.
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Affiliation(s)
| | - Yvette Bordelon
- Department of Neurology, University of California Los Angeles, Los Angeles, CA 90095
| | - Adam M. Brickman
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain
- Department of Neuropsychology, Columbia University College of Physicians and Surgeons, New York NY 10032
- Department of Neurology, Columbia University College of Physicians and Surgeons, New York NY 10032
| | - Sergio Angulo
- The Robert F. Furchgott Center for Neural and Behavioral Science, Departments of Neurology
- Physiology/Pharmacology, State University of New York Downstate Medical Center, Brooklyn, NY 11203
| | - Usman Khan
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain
- Physiology/Pharmacology, State University of New York Downstate Medical Center, Brooklyn, NY 11203
| | - Jordan Muraskin
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain
- Department of Biomedical Engineering, Columbia University College of Physicians and Surgeons, New York NY 10032
| | - Erica Y. Griffith
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain
- Department of Neuropsychology, Columbia University College of Physicians and Surgeons, New York NY 10032
| | - Paula Wasserman
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain
| | | | - Jean Paul Vonsattel
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain
- Department of Pathology, Columbia University College of Physicians and Surgeons, New York NY 10032
| | - Karen Marder
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain
- Department of Neurology, Columbia University College of Physicians and Surgeons, New York NY 10032
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York NY 10032
| | - Scott A. Small
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain
- Department of Neurology, Columbia University College of Physicians and Surgeons, New York NY 10032
| | - Herman Moreno
- Department of Neurology, Columbia University College of Physicians and Surgeons, New York NY 10032
- The Robert F. Furchgott Center for Neural and Behavioral Science, Departments of Neurology
- Physiology/Pharmacology, State University of New York Downstate Medical Center, Brooklyn, NY 11203
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Network of brain protein level changes in glutaminase deficient fetal mice. J Proteomics 2013; 80:236-49. [PMID: 23376484 DOI: 10.1016/j.jprot.2013.01.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 12/17/2012] [Accepted: 01/05/2013] [Indexed: 02/06/2023]
Abstract
Glutaminase is a multifunctional enzyme encoded by gene Gls involved in energy metabolism, ammonia trafficking and regeneration of neurotransmitter glutamate. To address the proteomic basis for the neurophenotypes of glutaminase-deficient mice, brain proteins from late gestation wild type, Gls+/- and Gls-/- male mice were subjected to two-dimensional gel electrophoresis, with subsequent identification by mass spectrometry using nano-LC-ESI-MS/MS. Protein spots that showed differential genotypic variation were quantified by immunoblotting. Differentially expressed proteins unambiguously identified by MS/MS included neurocalcin delta, retinol binding protein-1, reticulocalbin-3, cytoskeleton proteins fascin and tropomyosin alpha-4-chain, dihydropyrimidinase-related protein-5, apolipoprotein IV and proteins from protein metabolism proteasome subunits alpha type 2, type 7, heterogeneous nuclear ribonucleoprotein C1/C2 and H, voltage-gated anion-selective channel proteins 1 and 2, ATP synthase subunit β and transitional endoplasmic reticulum ATPase. An interaction network determined by Ingenuity Pathway Analysis revealed a link between glutaminase and calcium, Akt and retinol signaling, cytoskeletal elements, ATPases, ion channels, protein synthesis and the proteasome system, intermediary, nucleic acid and lipid metabolism, huntingtin, guidance cues, transforming growth factor beta-1 and hepatocyte nuclear factor 4-alpha. The network identified involves (a) cellular assembly and organization and (b) cell signaling and cell cycle, suggesting that Gls is crucial for neuronal maturation.
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Marsman A, van den Heuvel MP, Klomp DWJ, Kahn RS, Luijten PR, Hulshoff Pol HE. Glutamate in schizophrenia: a focused review and meta-analysis of ¹H-MRS studies. Schizophr Bull 2013; 39:120-9. [PMID: 21746807 PMCID: PMC3523901 DOI: 10.1093/schbul/sbr069] [Citation(s) in RCA: 334] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Schizophrenia is a severe chronic psychiatric illness, characterized by hallucinations and delusions. Decreased brain volumes have been observed in the disease, although the origin of these changes is unknown. Changes in the n-methyl-d-aspartate (NMDA)-receptor mediated glutamatergic neurotransmission are implicated, since it is hypothesized that NMDA-receptor dysfunction in schizophrenia leads to increased glutamate release, which can have excitotoxic effects. However, the magnitude and extent of changes in glutamatergic metabolites in schizophrenia are not clear. With (1)H magnetic resonance spectroscopy ((1)H-MRS), in vivo information about glutamate and glutamine concentrations can be obtained in the brain. A systematic search through the MEDLINE database was conducted to identify relevant (1)H-MRS studies that examined differences in glutamate and glutamine concentrations between patients with schizophrenia and healthy control subjects. Twenty-eight studies were identified and included a total of 647 patients with schizophrenia and 608 healthy-control subjects. For each study, Cohen's d was calculated and main effects for group analyses were performed using the random-effects model. Medial frontal region glutamate was decreased and glutamine was increased in patients with schizophrenia as compared with healthy individuals. Group-by-age associations revealed that in patients with schizophrenia, glutamate and glutamine concentrations decreased at a faster rate with age as compared with healthy controls. This could reflect aberrant processes in schizophrenia, such as altered synaptic activity, changed glutamate receptor functioning, abnormal glutamine-glutamate cycling, or dysfunctional glutamate transport.
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Affiliation(s)
- Anouk Marsman
- Department of Psychiatry, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Internal address A.01.126, PO Box 85500, 3508 GA Utrecht, The Netherlands.
| | - Martijn P. van den Heuvel
- Department of Psychiatry, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Dennis W. J. Klomp
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - René S. Kahn
- Department of Psychiatry, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Peter R. Luijten
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Hilleke E. Hulshoff Pol
- Department of Psychiatry, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands
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Cacabelos R, Cacabelos P, Aliev G. Genomics of schizophrenia and pharmacogenomics of antipsychotic drugs. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/ojpsych.2013.31008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Mihali A, Subramani S, Kaunitz G, Rayport S, Gaisler-Salomon I. Modeling resilience to schizophrenia in genetically modified mice: a novel approach to drug discovery. Expert Rev Neurother 2012; 12:785-99. [PMID: 22853787 DOI: 10.1586/ern.12.60] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Complex psychiatric disorders, such as schizophrenia, arise from a combination of genetic, developmental, environmental and social factors. These vulnerabilities can be mitigated by adaptive factors in each of these domains engendering resilience. Modeling resilience in mice using transgenic approaches offers a direct path to intervention, as resilience mutations point directly to therapeutic targets. As prototypes for this approach, we discuss the three mouse models of schizophrenia resilience, all based on modulating glutamatergic synaptic transmission. This motivates the broader development of schizophrenia resilience mouse models independent of specific pathophysiological hypotheses as a strategy for drug discovery. Three guiding validation criteria are presented. A resilience-oriented approach should identify pharmacologically tractable targets and in turn offer new insights into pathophysiological mechanisms.
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Affiliation(s)
- Andra Mihali
- Department of Psychiatry, Columbia University, New York State Psychiatric Institute, 1051 Riverside Drive, Unit 62, New York, NY 10032, USA
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Brain-specific overexpression of trace amine-associated receptor 1 alters monoaminergic neurotransmission and decreases sensitivity to amphetamine. Neuropsychopharmacology 2012; 37:2580-92. [PMID: 22763617 PMCID: PMC3473323 DOI: 10.1038/npp.2012.109] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Trace amines (TAs) such as β-phenylethylamine, p-tyramine, or tryptamine are biogenic amines found in the brain at low concentrations that have been implicated in various neuropsychiatric disorders like schizophrenia, depression, or attention deficit hyperactivity disorder. TAs are ligands for the recently identified trace amine-associated receptor 1 (TAAR1), an important modulator of monoamine neurotransmission. Here, we sought to investigate the consequences of TAAR1 hypersignaling by generating a transgenic mouse line overexpressing Taar1 specifically in neurons. Taar1 transgenic mice did not show overt behavioral abnormalities under baseline conditions, despite augmented extracellular levels of dopamine and noradrenaline in the accumbens nucleus (Acb) and of serotonin in the medial prefrontal cortex. In vitro, this was correlated with an elevated spontaneous firing rate of monoaminergic neurons in the ventral tegmental area, dorsal raphe nucleus, and locus coeruleus as the result of ectopic TAAR1 expression. Furthermore, Taar1 transgenic mice were hyposensitive to the psychostimulant effects of amphetamine, as it produced only a weak locomotor activation and failed to alter catecholamine release in the Acb. Attenuating TAAR1 activity with the selective partial agonist RO5073012 restored the stimulating effects of amphetamine on locomotion. Overall, these data show that Taar1 brain overexpression causes hyposensitivity to amphetamine and alterations of monoaminergic neurotransmission. These observations confirm the modulatory role of TAAR1 on monoamine activity and suggest that in vivo the receptor is either constitutively active and/or tonically activated by ambient levels of endogenous agonist(s).
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58
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El Hage M, Masson J, Conjard-Duplany A, Ferrier B, Baverel G, Martin G. Brain slices from glutaminase-deficient mice metabolize less glutamine: a cellular metabolomic study with carbon 13 NMR. J Cereb Blood Flow Metab 2012; 32:816-24. [PMID: 22373647 PMCID: PMC3345920 DOI: 10.1038/jcbfm.2012.22] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In the brain, glutaminase is considered to have a key role in the provision of glutamate, a major excitatory neurotransmitter. Brain slices obtained from wild-type (control) and glutaminase-deficient (GLS1+/-) mice were incubated without glucose and with 5 or 1 mmol/L [3-(13)C]glutamine as substrate. At the end of the incubation, substrate removal and product formation were measured by both enzymatic and carbon 13 nuclear magnetic resonance ((13)C-NMR) techniques. Slices from GLS1+/- mice consumed less [3-(13)C]glutamine and accumulated less [3-(13)C]glutamate. They also produced less (13)CO(2) but accumulated amounts of (13)C-aspartate and (13)C-gamma-aminobutyric acid (GABA) that were similar to those found with brain slices from control mice. The newly formed glutamine observed in slices from control mice remained unchanged in slices from GLS1+/- mice. As expected, flux through glutaminase in slices from GLS1+/- mice was found diminished. Fluxes through all enzymes of the tricarboxylic acid cycle were also reduced in brain slices from GLS1+/- mice except through malate dehydrogenase with 5 mmol/L [3-(13)C]glutamine. The latter diminutions are consistent with the decreases in the production of (13)CO(2) also observed in the slices from these mice. It is concluded that the genetic approach used in this study confirms the key role of glutaminase for the provision of glutamate.
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Affiliation(s)
- Maha El Hage
- Metabolys, Faculté de Médecine R.T.H. Laennec, 7–11 rue G. Paradin, Lyon Cedex 08, France.
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Moreno H, Burghardt NS, Vela-Duarte D, Masciotti J, Hua F, Fenton AA, Schwaller B, Small SA. The absence of the calcium-buffering protein calbindin is associated with faster age-related decline in hippocampal metabolism. Hippocampus 2012; 22:1107-20. [PMID: 21630373 PMCID: PMC3166382 DOI: 10.1002/hipo.20957] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/18/2011] [Indexed: 02/01/2023]
Abstract
Although reductions in the expression of the calcium-buffering proteins calbindin D-28K (CB) and parvalbumin (PV) have been observed in the aging brain, it is unknown whether these changes contribute to age-related hippocampal dysfunction. To address this issue, we measured basal hippocampal metabolism and hippocampal structure across the lifespan of C57BL/6J, calbindin D-28k knockout (CBKO) and parvalbumin knockout (PVKO) mice. Basal metabolism was estimated using steady state relative cerebral blood volume (rCBV), which is a variant of fMRI that provides the highest spatial resolution, optimal for the analysis of individual subregions of the hippocampal formation. We found that like primates, normal aging in C57BL/6J mice is characterized by an age-dependent decline in rCBV-estimated dentate gyrus (DG) metabolism. Although abnormal hippocampal fMRI signals were observed in CBKO and PVKO mice, only CBKO mice showed accelerated age-dependent decline of rCBV-estimated metabolism in the DG. We also found age-independent structural changes in CBKO mice, which included an enlarged hippocampus and neocortex as well as global brain hypertrophy. These metabolic and structural changes in CBKO mice correlated with a deficit in hippocampus-dependent learning in the active place avoidance task. Our results suggest that the decrease in CB that occurs during normal aging is involved in age-related hippocampal metabolic decline. Our findings also illustrate the value of using multiple MRI techniques in transgenic mice to investigate mechanisms involved in the functional and structural changes that occur during aging.
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Affiliation(s)
- Herman Moreno
- SUNY Downstate Medical Center, The Robert F. Furchgott Center for Neural and Behavioral Science, Department of Neurology and Pharmacology &Physiology, 450 Clarkson Avenue Box 29, Brooklyn NY USA 11203, Phone: (718) 270-4660
| | - Nesha S. Burghardt
- Columbia University, Departments of Neuroscience, Pharmacology & Psychiatry, 1051 Riverside Drive, Unit 87, New York, NY USA 10032
| | - Daniel Vela-Duarte
- SUNY Downstate Medical Center, Department of Pharmacology & Physiology, 450 Clarkson Avenue Box 29, Brooklyn NY USA 11203
| | - James Masciotti
- Columbia University, Department of Biomedical Engineering, 630 West 168th Street, PH # 19, New York, NY USA 10032, Columbia University
| | - Fan Hua
- Columbia University, Department of Radiology, 630 West 168th Street, PH # 19, New York, NY USA 10032
| | - André A. Fenton
- New York University, Center for Neural Science, New York University, 4 Washington Place, New York, NY USA 10003-6621 And SUNY Downstate Medical Center, The Robert F. Furchgott Center for Neural and Behavioral Science, Department of Pharmacology & Physiology, 450 Clarkson Avenue, Brooklyn NY USA 11203
| | - Beat Schwaller
- University of Fribourg, Unit of Anatomy, Department of Medicine, 1, route Albert-Gockel, CH-1700 Fribourg Switzerland
| | - Scott A. Small
- Columbia University, School of Physicians and Surgeons, 630 West 168th Street, PH # 19, New York, NY USA 10032
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Gaisler-Salomon I, Wang Y, Chuhma N, Zhang H, Golumbic YN, Mihali A, Arancio O, Sibille E, Rayport S. Synaptic underpinnings of altered hippocampal function in glutaminase-deficient mice during maturation. Hippocampus 2012; 22:1027-39. [PMID: 22431402 DOI: 10.1002/hipo.22014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/13/2012] [Indexed: 12/24/2022]
Abstract
Glutaminase-deficient mice (GLS1 hets), with reduced glutamate recycling, have a focal reduction in hippocampal activity, mainly in CA1, and manifest behavioral and neurochemical phenotypes suggestive of schizophrenia resilience. To address the basis for the hippocampal hypoactivity, we examined synaptic plastic mechanisms and glutamate receptor expression. Although baseline synaptic strength was unaffected in Schaffer collateral inputs to CA1, we found that long-term potentiation was attenuated. In wild-type (WT) mice, GLS1 gene expression was highest in the hippocampus and cortex, where it was reduced by about 50% in GLS1 hets. In other brain regions with lower WT GLS1 gene expression, there were no genotypic reductions. In adult GLS1 hets, NMDA receptor NR1 subunit gene expression was reduced, but not AMPA receptor GluR1 subunit gene expression. In contrast, juvenile GLS1 hets showed no reductions in NR1 gene expression. In concert with this, adult GLS1 hets showed a deficit in hippocampal-dependent contextual fear conditioning, whereas juvenile GLS1 hets did not. These alterations in glutamatergic synaptic function may partly explain the hippocampal hypoactivity seen in the GLS1 hets. The maturity-onset reduction in NR1 gene expression and in contextual learning supports the premise that glutaminase inhibition in adulthood should prove therapeutic in schizophrenia.
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Moghaddam B, Javitt D. From revolution to evolution: the glutamate hypothesis of schizophrenia and its implication for treatment. Neuropsychopharmacology 2012; 37:4-15. [PMID: 21956446 PMCID: PMC3238069 DOI: 10.1038/npp.2011.181] [Citation(s) in RCA: 702] [Impact Index Per Article: 58.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 07/21/2011] [Accepted: 07/21/2011] [Indexed: 12/12/2022]
Abstract
Glutamate is the primary excitatory neurotransmitter in mammalian brain. Disturbances in glutamate-mediated neurotransmission have been increasingly documented in a range of neuropsychiatric disorders including schizophrenia, substance abuse, mood disorders, Alzheimer's disease, and autism-spectrum disorders. Glutamatergic theories of schizophrenia are based on the ability of N-methyl-D-aspartate receptor (NMDAR) antagonists to induce schizophrenia-like symptoms, as well as emergent literature documenting disturbances of NMDAR-related gene expression and metabolic pathways in schizophrenia. Research over the past two decades has highlighted promising new targets for drug development based on potential pre- and postsynaptic, and glial mechanisms leading to NMDAR dysfunction. Reduced NMDAR activity on inhibitory neurons leads to disinhibition of glutamate neurons increasing synaptic activity of glutamate, especially in the prefrontal cortex. Based on this mechanism, normalizing excess glutamate levels by metabotropic glutamate group 2/3 receptor agonists has led to potential identification of the first non-monoaminergic target with comparable efficacy as conventional antipsychotic drugs for treating positive and negative symptoms of schizophrenia. In addition, NMDAR has intrinsic modulatory sites that are active targets for drug development, several of which show promise in preclinical/early clinical trials targeting both symptoms and cognition. To date, most studies have been done with orthosteric agonists and/or antagonists at specific sites. However, allosteric modulators, both positive and negative, may offer superior efficacy with less danger of downregulation.
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Affiliation(s)
- Bita Moghaddam
- Department of Neuroscience and Psychiatry, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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Rao R, Tkac I, Schmidt AT, Georgieff MK. Fetal and neonatal iron deficiency causes volume loss and alters the neurochemical profile of the adult rat hippocampus. Nutr Neurosci 2011; 14:59-65. [PMID: 21605501 DOI: 10.1179/1476830511y.0000000001] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
OBJECTIVE Perinatal iron deficiency results in persistent hippocampus-based cognitive deficits in adulthood despite iron supplementation. The objective of the present study was to determine the long-term effects of perinatal iron deficiency and its treatment on hippocampal anatomy and neurochemistry in formerly iron-deficient young adult rats. METHODS Perinatal iron deficiency was induced using a low-iron diet during gestation and the first postnatal week in male rats. Hippocampal size was determined using volumetric magnetic resonance imaging at 8 weeks of age. Hippocampal neurochemical profile, consisting of 17 metabolites indexing neuronal and glial integrity, energy reserves, amino acids, and myelination, was quantified using high-field in vivo (1)H NMR spectroscopy at 9.4T (N = 11) and compared with iron-sufficient control group (N = 10). RESULTS The brain iron concentration was 56% lower than the control group at 7 days of age in the iron-deficient group, but had recovered completely at 8 weeks. The cross-sectional area of the hippocampus was decreased by 12% in the formerly iron-deficient group (P = 0.0002). The hippocampal neurochemical profile was altered: relative to the control group, creatine, lactate, N-acetylaspartylglutamate, and taurine concentrations were 6-29% lower, and glutamine concentration 18% higher in the formerly iron-deficient hippocampus (P < 0.05). DISCUSSION Perinatal iron deficiency was associated with reduced hippocampal size and altered neurochemistry in adulthood, despite correction of brain iron deficiency. The neurochemical changes suggest suppressed energy metabolism, neuronal activity, and plasticity in the formerly iron-deficient hippocampus. These anatomic and neurochemical changes are consistent with previous structural and behavioral studies demonstrating long-term hippocampal dysfunction following perinatal iron deficiency.
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Affiliation(s)
- Raghavendra Rao
- Division of Neonatology, Department of Pediatrics, University of Minnesota, Minneapolis, MN, USA.
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63
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A pathophysiological framework of hippocampal dysfunction in ageing and disease. Nat Rev Neurosci 2011; 12:585-601. [PMID: 21897434 DOI: 10.1038/nrn3085] [Citation(s) in RCA: 678] [Impact Index Per Article: 52.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The hippocampal formation has been implicated in a growing number of disorders, from Alzheimer's disease and cognitive ageing to schizophrenia and depression. How can the hippocampal formation, a complex circuit that spans the temporal lobes, be involved in a range of such phenotypically diverse and mechanistically distinct disorders? Recent neuroimaging findings indicate that these disorders differentially target distinct subregions of the hippocampal circuit. In addition, some disorders are associated with hippocampal hypometabolism, whereas others show evidence of hypermetabolism. Interpreted in the context of the functional and molecular organization of the hippocampal circuit, these observations give rise to a unified pathophysiological framework of hippocampal dysfunction.
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Relationship between genetic variation in the glutaminase gene GLS1 and brain glutamine/glutamate ratio measured in vivo. Biol Psychiatry 2011; 70:169-74. [PMID: 21457947 PMCID: PMC3125415 DOI: 10.1016/j.biopsych.2011.01.033] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2010] [Revised: 01/27/2011] [Accepted: 01/28/2011] [Indexed: 12/18/2022]
Abstract
BACKGROUND Abnormalities in glutamatergic neurotransmission are implicated in several psychiatric disorders, but in vivo neurochemical studies of the glutamate (Glu) system have been hampered by a lack of adequate probes. By contrast, glutamine (Gln) and Glu can be quantified separately in proton magnetic resonance spectroscopy studies in vivo. Accumulating evidence suggests that the Gln/Glu ratio is a putative index of glutamatergic neurotransmission but interpretation of changes in the Gln/Glu ratio depends on the conditions of the system, including ammonia levels. METHODS Here, we explored whether variation in GLS1 (the gene encoding the brain isoform of glutaminase, which catalyzes Gln-to-Glu conversion) is associated with Gln/Glu measured in vivo in two brain regions (anterior cingulate cortex, parieto-occipital cortex). RESULTS A specific haplotype of four single nucleotide polymorphisms within GLS1 was significantly associated with Gln/Glu in the parieto-occipital cortex in an magnetic resonance spectroscopy-genetics dataset optimized for Gln/Glu detection (n = 42). This finding was replicated in a second magnetic resonance spectroscopy dataset that was optimized for γ-aminobutyric acid detection where Gln and Glu measurements could still be extracted (n = 40). CONCLUSIONS These findings suggest that genetic variation in a key component of glutamatergic machinery is associated with a putative in vivo index of glutamatergic neurotransmission. Thus, GLS1 genotype might provide insight into normal brain function and into the pathophysiology of many psychiatric conditions where glutamatergic neurotransmission has been implicated. It might also serve as a biomarker for predicting response to existing and novel therapeutic interventions in psychiatry that target glutamatergic neurotransmission.
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Kang L, Zhang Y, Zhang N, Zang L, Wang M, Cui X, Jiang Y. Identification of differentially expressed genes in ovaries of chicken attaining sexual maturity at different ages. Mol Biol Rep 2011; 39:3037-45. [PMID: 21691707 DOI: 10.1007/s11033-011-1066-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Accepted: 06/10/2011] [Indexed: 10/18/2022]
Abstract
In poultry as well as in other birds, sexual maturity is one of the important factors influencing female reproduction and egg production. In this study, cDNA-amplified fragment length polymorphism (cDNA-AFLP) differential display approach was used to identify genes related to sexual maturity. Using 54 EcoR I/Mse I selective primer combinations, totally 403 differentially expressed transcript-derived fragments (TDFs) were isolated, 27 of which belong to 25 unigenes. By real-time quantitative PCR (qPCR), the expression pattern of 13 genes was confirmed; among them, four genes including ZNF183 (P < 0.01), KIAA0700, CCT6A, and 23e 15 (P < 0.05) are significantly up-regulated and one gene (Loc418883) is significantly down-regulated (P < 0.01) in sexually mature ovaries compared to immature ones. The mRNA expression dynamics of ZNF183, CCT6A, 23e 15 and Loc418883 were further investigated in ovaries of 70-, 300- and 500-day-old commercial egg-laying hens: the expression level of CCT6A was the highest in 300-day-old hens (P < 0.05), while that of Loc418883 in 500-day-old hens was significantly higher than the other two stages (P < 0.01). The expression levels of ZNF183 and 23e 15 in ovary increase significantly from 70-day-old hens (P < 0.01) and 300-day-old (P < 0.05) to 500-day-old hens, respectively. The consistence of CCT6A expression and egg-laying performance suggests that CCT6A likely plays important role in sexual maturity in hens.
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Affiliation(s)
- Li Kang
- Lab of Animal Molecular Genetics, College of Animal Science, Shandong Agricultural University, Taian 271018, China
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Neuronal Glud1 (glutamate dehydrogenase 1) over-expressing mice: increased glutamate formation and synaptic release, loss of synaptic activity, and adaptive changes in genomic expression. Neurochem Int 2011; 59:473-81. [PMID: 21397652 DOI: 10.1016/j.neuint.2011.03.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Revised: 03/01/2011] [Accepted: 03/03/2011] [Indexed: 11/24/2022]
Abstract
Glutamate dehydrogenase 1 (GLUD1) is a mitochondrial enzyme expressed in all tissues, including brain. Although this enzyme is expressed in glutamatergic pathways, its function as a regulator of glutamate neurotransmitter levels is still not well defined. In order to gain an understanding of the role of GLUD1 in the control of glutamate levels and synaptic release in mammalian brain, we generated transgenic (Tg) mice that over-express this enzyme in neurons of the central nervous system. The Tg mice have increased activity of GLUD, as well as elevated levels and increased synaptic and depolarization-induced release of glutamate. These mice suffer age-associated losses of dendritic spines, nerve terminals, and neurons. The neuronal losses and dendrite structural changes occur in select regions of the brain. At the transcriptional level in the hippocampus, cells respond by increasing the expression of genes related to neurite growth and synapse formation, indications of adaptive or compensatory responses to the effects of increases in the release and action of glutamate at synapses. Because these Tg mice live to a relatively old age they are a good model of the effects of a "hyperglutamatergic" state on the aging process in the nervous system. The mice are also useful in defining the molecular pathways affected by the over-activation of GLUD in glutamatergic neurons of the brain and spinal cord.
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Hippocampal CA1 region shows differential regulation of gene expression in mice displaying extremes in behavioral sensitization to amphetamine: relevance for psychosis susceptibility? Psychopharmacology (Berl) 2011; 217:525-38. [PMID: 21537941 PMCID: PMC3180555 DOI: 10.1007/s00213-011-2313-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Accepted: 04/09/2011] [Indexed: 11/27/2022]
Abstract
RATIONALE Psychosis susceptibility is mediated in part by the dopaminergic neurotransmitter system. In humans, individual differences in vulnerability for psychosis are reflected in differential sensitivity for psychostimulants such as amphetamine. We hypothesize that the same genes and pathways underlying behavioral sensitization in mice are also involved in the vulnerability to psychosis. OBJECTIVES The aim of the current study was to investigate which genes and pathways may contribute to behavioral sensitization in different dopaminergic output areas in the mouse brain. METHODS We took advantage of the naturally occurring difference in psychostimulant sensitivity in DBA/2 mice and selected animals displaying extremes in behavioral sensitization to amphetamine. Subsequently, the dopamine output areas, prefrontal cortex, nucleus accumbens, and cornu ammonis 1 (CA1) area of the hippocampus, were isolated by laser microdissection and subjected to DNA microarray analysis 1 h after a challenge dose of amphetamine. RESULTS A large number of genes with differential expression between high and low responders were identified, with no overlap between brain regions. Validation of these gene expression changes with real-time quantitative polymerase chain reaction demonstrated that the most robust and reproducible effects on gene expression were in the CA1 region of the hippocampus. Interestingly, many of the validated genes in CA1 are members of the cAMP response element (CRE) family and targets of the glucocorticoid receptor (GR) and myocyte enhancer factor 2 (Mef2) transcription factors. CONCLUSION We hypothesize that CRE, Mef2, and GR signaling form a transcription regulating network, which underlies differential amphetamine sensitivity, and therefore, may play an important role in susceptibility to psychosis.
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Baharnoori M, Bartholomeusz C, Boucher AA, Buchy L, Chaddock C, Chiliza B, Föcking M, Fornito A, Gallego JA, Hori H, Huf G, Jabbar GA, Kang SH, El Kissi Y, Merchán-Naranjo J, Modinos G, Abdel-Fadeel NA, Neubeck AK, Ng HP, Novak G, Owolabi O, Prata DP, Rao NP, Riecansky I, Smith DC, Souza RP, Thienel R, Trotman HD, Uchida H, Woodberry KA, O'Shea A, DeLisi LE. The 2nd Schizophrenia International Research Society Conference, 10-14 April 2010, Florence, Italy: summaries of oral sessions. Schizophr Res 2010; 124:e1-62. [PMID: 20934307 PMCID: PMC4182935 DOI: 10.1016/j.schres.2010.09.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Revised: 08/30/2010] [Accepted: 09/01/2010] [Indexed: 01/06/2023]
Abstract
The 2nd Schizophrenia International Research Society Conference, was held in Florence, Italy, April 10-15, 2010. Student travel awardees served as rapporteurs of each oral session and focused their summaries on the most significant findings that emerged from each session and the discussions that followed. The following report is a composite of these reviews. It is hoped that it will provide an overview for those who were present, but could not participate in all sessions, and those who did not have the opportunity to attend, but who would be interested in an update on current investigations ongoing in the field of schizophrenia research.
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Affiliation(s)
- Moogeh Baharnoori
- Douglas Mental Health University Institute, Department of Psychiatry, McGill University, 6875 LaSalle Blvd, Montreal, Quebec, Canada H4H 1R3, phone (514) 761-6131 ext 3346,
| | - Cali Bartholomeusz
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne, Level 2-3, Alan Gilbert Building, 161 Barry St, Carlton South, Victoria 3053, Australia, phone +61 3 8344 1878, fax +61 3 9348 0469,
| | - Aurelie A. Boucher
- Brain and Mind Research Institute, 100 Mallett Street, Camperdown NSW 2050, Australia, phone +61 (0)2 9351 0948, fax +61 (0)2 9351 0652,
| | - Lisa Buchy
- Douglas Hospital Research Centre, 6875 LaSalle Blvd, Verdun, Québec, Canada, H4H 1R3 phone: 514-761-6131 x 3386, fax: 514-888-4064,
| | - Christopher Chaddock
- PO67, Section of Neuroimaging, Division of Psychological Medicine, Institute of Psychiatry, De Crespigny Park, London, SE5 8AF, phone 020 7848 0919, mobile 07734 867854 fax 020 7848 0976,
| | - Bonga Chiliza
- Department of Psychiatry, University of Stellenbosch, Tygerberg, 7505, South Africa, phone: +27 (0)21 9389227, fax +27 (0)21 9389738,
| | - Melanie Föcking
- Department of Psychiatry, Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, Dublin 9, Ireland, phone +353 1 809 3857, fax +353 1 809 3741,
| | - Alex Fornito
- Brain Mapping Unit, Department of Psychiatry, University of Cambridge, Downing Site, Downing St, Cambridge, UK, CB2 3EB, phone +44 (0) 1223 764670, fax +44 (0) 1223 336581,
| | - Juan A. Gallego
- The Zucker Hillside Hospital, Psychiatry Research, 75-59 263rd St, Glen Oaks, NY 11004, phone 718-470-8177, fax 718-343-1659,
| | - Hiroaki Hori
- Department of Mental Disorder Research, National Institute of Neuroscience, NCNP, 4-1-1, Ogawahigashi, Kodaira, Tokyo, 187-8502, JAPAN, phone: +81 42 341 2711; fax: +81 42 346 1744,
| | - Gisele Huf
- National Institute of Quality Control in Health - Oswaldo Cruz Foundation.Av. Brasil 4365 Manguinhos Rio de Janeiro RJ BRAZIL 21045-900, phone + 55 21 38655112, fax + 55 21 38655139,
| | - Gul A. Jabbar
- Clinical Research Coordinator, Harvard Medical School Department of Psychiatry, 940 Belmont Street 2-B, Brockton, MA 02301, office (774) 826-1624, cell (845) 981-9514, fax (774) 286-1076,
| | - Shi Hyun Kang
- Seoul National Hospital, 30-1 Junggok3-dong Gwangjin-gu, Seoul, 143-711, Korea, phone +82-2-2204-0326, fax +82-2-2204-0394,
| | - Yousri El Kissi
- Psychiatry department, Farhat Hached Hospital. Ibn Jazzar Street, 4002 Sousse. Tunisia. phone + 216 98468626, fax + 216 73226702,
| | - Jessica Merchán-Naranjo
- Adolescent Unit. Department of Psychiatry. Hospital General Universitario Gregorio Marañón. Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Spain. C/Ibiza 43, C.P:28009, phone +34 914265005, fax +34 914265004,
| | - Gemma Modinos
- Department of Psychosis Studies (PO67), Institute of Psychiatry, King's College London, King's Health Partners, De Crespigny Park, SE5 8AF London, United Kingdo, phone +44 (0)20 78480917, fax +44 (0)20 78480976,
| | - Nashaat A.M. Abdel-Fadeel
- Minia University, Egypt, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, phone 617 953 0414, fax 617-998-5007, ,
| | - Anna-Karin Neubeck
- Project Manager at Karolinska Institute, Skinnarviksringen 12, 117 27 Stockholm, Sweden, phone +46708777908,
| | - Hsiao Piau Ng
- Singapore Bioimaging Consortium, A*STAR, Singapore; Department of Psychiatry, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, phone 857-544-0192, fax 617-525-6150,
| | - Gabriela Novak
- University of Toronto, Medical Sciences Building, Room 4345, 1 King's College Circle, Toronto, Ontario, M5S 1A8, phone (416) 946-8219, fax (416) 971-2868,
| | - Olasunmbo.O. Owolabi
- Department of Anatomy, Faculty of Basic Medical Sciences, College of Health Science University of Ilorin, Ilorin, Nigeria, phone +2348030764811,
| | - Diana P. Prata
- Department of Psychosis Studies, King’s College London, King’s Health Partners, Institute of Psychiatry, De Crespigny Park, London, SE5 8AF, UK, phone +44(0)2078480917, fax +44(0)2078480976,
| | - Naren P. Rao
- Department of Psychiatry, National Institute of Mental Health and Neurosciences, Hosur Road, Bangalore, 560029 Karnataka, India, phone +91 9448342379,
| | - Igor Riecansky
- Address: Institute of Normal and Pathological Physiology, Slovak Academy of Sciences, Sienkiewiczova 1, 813 71 Bratislava, Slovakia, phone +421-2-52 92 62 76, fax +421-2-52 96 85 16,
| | - Darryl C. Smith
- 3336 Mt Pleasant St. NW #2, Washington, DC 20010, phone 202.494.3892,
| | - Renan P. Souza
- Centre for Addiction and Mental Health 250 College St R31 Toronto - Ontario - Canada M5T1R8, phone +14165358501 x4883, fax +14169794666,
| | - Renate Thienel
- Postdoctoral Research Fellow, PRC Brain and Mental Health, University of Newcastle, Mc Auley Centre Level 5, Mater Hospital, Edith Street, Waratah NSW 2298, phone +61 (2) 40335636,
| | - Hanan D. Trotman
- 36 Eagle Row, Atlanta, GA 30322, phone 404-727-8384, fax 404-727-1284,
| | - Hiroyuki Uchida
- Department of Neuropsychiatry, Keio University School of Medicine, Psychopharmacology Research Program, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan, phone +81.3.3353.1211(x62454), fax +81.3.5379.0187,
| | - Kristen A. Woodberry
- Landmark Center 2 East, 401 Park Drive, Boston, MA 02215, phone 617-998-5022, fax 617-998-5007,
| | - Anne O'Shea
- Coordinator of reports. Harvard Medical School, VA Boston Healthcare System, 940 Belmont Street, Brockton, MA 02301, phone 774-826-1374, anne_o’
| | - Lynn E. DeLisi
- VA Boston Healthcare System and Harvard Medical School, 940 Belmont Street, Brockton, MA 02301, phone 774-826-1355, fax 774-826-2721
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Galloway MP, Ghoddoussi F, Needleman R, Brusilow WS. Glutamate as a target in Tourette syndrome and other neuropsychiatric disorders. J Neurol Sci 2010. [DOI: 10.1016/j.jns.2010.03.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Abstract
AbstractGlutaminase is considered as the main glutamate producer enzyme in brain. Consequently, the enzyme is essential for both glutamatergic and gabaergic transmissions. Glutamine-derived glutamate and ammonia, the products of glutaminase reaction, fulfill crucial roles in energy metabolism and in the biosynthesis of basic metabolites, such as GABA, proteins and glutathione. However, glutamate and ammonia are also hazardous compounds and danger lurks in their generation beyond normal physiological thresholds; hence, glutaminase activity must be carefully regulated in the mammalian brain. The differential distribution and regulation of glutaminase are key factors to modulate the metabolism of glutamate and glutamine in brain. The discovery of novel isoenzymes, protein interacting partners and subcellular localizations indicate new functions for brain glutaminase. In this short review, we summarize recent findings that point consistently towards glutaminase as a multifaceted protein able to perform different tasks. Finally, we will highlight the involvement of glutaminase in pathological states and its consideration as a potential therapeutic target.
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Ghoddoussi F, Galloway MP, Jambekar A, Bame M, Needleman R, Brusilow WS. Methionine sulfoximine, an inhibitor of glutamine synthetase, lowers brain glutamine and glutamate in a mouse model of ALS. J Neurol Sci 2010; 290:41-7. [DOI: 10.1016/j.jns.2009.11.013] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Revised: 11/24/2009] [Accepted: 11/24/2009] [Indexed: 11/24/2022]
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Gaisler-Salomon I, Schobel SA, Small SA, Rayport S. How high-resolution basal-state functional imaging can guide the development of new pharmacotherapies for schizophrenia. Schizophr Bull 2009; 35:1037-44. [PMID: 19828591 PMCID: PMC2762634 DOI: 10.1093/schbul/sbp114] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We describe here a coordinated brain imaging and animal models approach in which we have shown that the hippocampal CA1 region is a principal node in schizophrenia pathogenesis and have identified a novel treatment approach to the disorder based on inhibition of glutamate release. To identify biomarkers, we have focused on the putative prodromal period, typically lasting a few years, preceding the first onset of psychosis. About one-third of a high-risk cohort followed prospectively for 2.5 years will progress to threshold psychosis, making it possible to perform a relatively short prospective study. We have utilized a technological development in functional imaging techniques in which we measure cerebral blood volume (CBV), which allows for interrogation of subregions of the brain in the basal state at submillimeter resolution. Measurements of CBV in schizophrenia as well as in high-risk or prodromal stages can then pinpoint brain subregions differentially targeted during the earliest stages of the disorder. Our data suggest that the CA1 subfield of the hippocampal formation is most consistently implicated across disease stages, identifying a putative biomarker suitable for guiding drug development. Our studies in transgenic mice mutant in the glutamate synthetic enzyme glutaminase support the hypothesis that CA1 hyperfunction is due to altered glutamatergic neurotransmission. As a proof of principle, the glutaminase-deficient mice suggest that pharmacotherapies that reduce glutamatergic neurotransmission in the CA1 subfield may be a uniquely effective therapeutic strategy in schizophrenia and preventative in prodromal stages of the disorder.
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Affiliation(s)
- Inna Gaisler-Salomon
- Department of Psychiatry, Columbia University, New York, NY 10032,Department of Molecular Therapeutics, NYS Psychiatric Institute, New York, NY 10032
| | - Scott A. Schobel
- Department of Psychiatry, Columbia University, New York, NY 10032,Department of Translational Imaging, NYS Psychiatric Institute, New York, NY 10032
| | - Scott A. Small
- Department of Neurology, Columbia University, New York, NY 10032
| | - Stephen Rayport
- Department of Psychiatry, Columbia University, New York, NY 10032,Department of Molecular Therapeutics, NYS Psychiatric Institute, New York, NY 10032,To whom correspondence should be addressed; tel: 212-543-5641, fax: 212-504-3135, e-mail:
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