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Modulation of circuit oscillations in the rat anterior cingulate cortex (ACC) in vitro by mGlu2 metabotropic glutamate receptors and alleviation of the effects of phencyclidine-induced NMDA-receptor hypofunction. Pharmacol Biochem Behav 2023; 223:173532. [PMID: 36822254 DOI: 10.1016/j.pbb.2023.173532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/10/2023] [Accepted: 02/16/2023] [Indexed: 02/23/2023]
Abstract
Aberrant cortical oscillations in the beta and gamma range are associated with symptoms of schizophrenia and other psychiatric conditions. We have thus investigated the ability of anterior cingulate cortex (ACC) in vitro to generate beta and gamma oscillations, and how these are affected by Group II metabotropic glutamate (mGlu) receptor activation and blockade of N-methyl-d-aspartate (NMDA) receptors. Activation of Group II mGlu receptors, and mGlu2 specifically, with orthosteric agonists reduced the power of both beta and gamma oscillations in ACC without a significant effect on oscillation peak frequencies. The NMDA receptor blocker phencyclidine (PCP), known to evoke certain schizophrenia-like symptoms in humans, elevated the power of beta oscillations in ACC and caused a shift in oscillation frequency from the gamma range to the beta range. These enhanced beta oscillations were reduced by the Group II mGlu receptor agonists. These results show that Group II mGlu receptors, and specifically mGlu2, modulate network oscillations. Furthermore, attenuation of the effect of PCP suggests that mGlu2 receptors may stabilise aberrant network activity. These results underline the importance of Group II mGlu receptors, and particularly mGlu2, as targets for the treatment of neuropsychiatric and neurodegenerative diseases.
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Gene Expression and Epigenetic Regulation in the Prefrontal Cortex of Schizophrenia. Genes (Basel) 2023; 14:genes14020243. [PMID: 36833173 PMCID: PMC9957055 DOI: 10.3390/genes14020243] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/03/2023] [Accepted: 01/13/2023] [Indexed: 01/19/2023] Open
Abstract
Schizophrenia pathogenesis remains challenging to define; however, there is strong evidence that the interaction of genetic and environmental factors causes the disorder. This paper focuses on transcriptional abnormalities in the prefrontal cortex (PFC), a key anatomical structure that determines functional outcomes in schizophrenia. This review summarises genetic and epigenetic data from human studies to understand the etiological and clinical heterogeneity of schizophrenia. Gene expression studies using microarray and sequencing technologies reported the aberrant transcription of numerous genes in the PFC in patients with schizophrenia. Altered gene expression in schizophrenia is related to several biological pathways and networks (synaptic function, neurotransmission, signalling, myelination, immune/inflammatory mechanisms, energy production and response to oxidative stress). Studies investigating mechanisms driving these transcriptional abnormalities focused on alternations in transcription factors, gene promoter elements, DNA methylation, posttranslational histone modifications or posttranscriptional regulation of gene expression mediated by non-coding RNAs.
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Defining the Homo- and Heterodimerization Propensities of Metabotropic Glutamate Receptors. Cell Rep 2021; 31:107605. [PMID: 32375054 PMCID: PMC7271767 DOI: 10.1016/j.celrep.2020.107605] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 03/10/2020] [Accepted: 04/10/2020] [Indexed: 01/02/2023] Open
Abstract
The eight metabotropic glutamate receptors (mGluRs) serve critical modulatory roles throughout the nervous system. The molecular diversity of mGluRs is thought to be further expanded by the formation of heterodimers, but the co-expression of mGluR subtypes at the cellular level and the relative propensities of heterodimer formation are not well known. Here, we analyze single-cell RNA sequencing data and find that cortical pyramidal cells express multiple mGluR subtypes with distinct profiles for different receptor combinations. We then develop quantitative, fluorescence-based assays to define the relative homo- and heterodimer propensities across group-I, -II, and -III mGluRs. We find a strong preference for heterodimerization in a number of cases, including mGluR2 with mGluR3, which we confirm in frontal cortex using in situ RNA hybridization and co-immunoprecipitation. Together, our findings support the biological relevance of mGluR heterodimerization and highlight the complex landscape of mGluR populations in the brain.
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Bryant JE, Lahti AC, Briend F, Kraguljac NV. White Matter Neurometabolic Signatures Support the Deficit and Nondeficit Distinction in Antipsychotic-Naïve First-Episode Psychosis Patients. Schizophr Bull 2021; 47:1068-1076. [PMID: 33693906 PMCID: PMC8266628 DOI: 10.1093/schbul/sbab014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The deficit syndrome is thought to be a more homogenous clinical subgroup within the syndrome of schizophrenia that is characterized by enduring negative symptoms. It is hypothesized that distinct pathophysiological processes underlie the subtypes, where the deficit syndrome reflects an early onset nonprogressive developmental process, and the nondeficit form of the illness is characterized by attenuated neuroplasticity secondary to elevated glutamate levels. We used single-voxel magnetic resonance spectroscopy (PRESS; TE: 30 ms) to measure left frontal white matter neurometabolite levels in 61 antipsychotic-naïve first-episode psychosis patients (39 who did not display deficit features, 22 who did display deficit features, assessed with the Schedule for the Deficit Syndrome) and 59 healthy controls. Metabolite levels were quantified with the LCModel. We used a MANCOVA to determine neurometabolite differences between healthy controls, deficit syndrome patients, and nondeficit patients. We report a significant group difference when all metabolites were considered jointly (F[10,208] = 2.16; P = .02). Post hoc analyses showed that patients presenting without deficit features had higher glutamate levels than patients with deficit features and controls. Patients presenting without deficit features also had significantly higher myoinositol levels than controls; myoinositol levels were trend-level higher in patients presenting with deficit features compared to controls. Our data support the idea that the pathophysiology of patients presenting without deficit features may differ from those presenting with deficit features.
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Affiliation(s)
- James Edward Bryant
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, SC 501, Birmingham, AL, USA
| | - Adrienne Carol Lahti
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, SC 501, Birmingham, AL, USA
| | - Frederic Briend
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, SC 501, Birmingham, AL, USA,UMR1253, iBrain, Université de Tours, Inserm, Tours, France
| | - Nina Vanessa Kraguljac
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, SC 501, Birmingham, AL, USA,To whom correspondence should be addressed; tel: 205-996-7171, e-mail:
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Cieślik P, Wierońska JM. Regulation of Glutamatergic Activity via Bidirectional Activation of Two Select Receptors as a Novel Approach in Antipsychotic Drug Discovery. Int J Mol Sci 2020; 21:ijms21228811. [PMID: 33233865 PMCID: PMC7699963 DOI: 10.3390/ijms21228811] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 11/10/2020] [Accepted: 11/16/2020] [Indexed: 12/14/2022] Open
Abstract
Schizophrenia is a mental disorder that affects approximately 1-2% of the population and develops in early adulthood. The disease is characterized by positive, negative, and cognitive symptoms. A large percentage of patients with schizophrenia have a treatment-resistant disease, and the risk of developing adverse effects is high. Many researchers have attempted to introduce new antipsychotic drugs to the clinic, but most of these treatments failed, and the diversity of schizophrenic symptoms is one of the causes of disappointing results. The present review summarizes the results of our latest papers, showing that the simultaneous activation of two receptors with sub-effective doses of their ligands induces similar effects as the highest dose of each compound alone. The treatments were focused on inhibiting the increased glutamate release responsible for schizophrenia arousal, without interacting with dopamine (D2) receptors. Ligands activating metabotropic receptors for glutamate, GABAB or muscarinic receptors were used, and the compounds were administered in several different combinations. Some combinations reversed all schizophrenia-related deficits in animal models, but others were active only in select models of schizophrenia symptoms (i.e., cognitive or negative symptoms).
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6
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Singh DR, Pandey K, Mishra AK, Pandey P, Vivcharuk V. Glutamate binding triggers monomerization of unliganded mGluR2 dimers. Arch Biochem Biophys 2020; 697:108632. [PMID: 33075300 DOI: 10.1016/j.abb.2020.108632] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 10/01/2020] [Accepted: 10/14/2020] [Indexed: 11/16/2022]
Abstract
The Metabotropic glutamate receptor 2 (mGluR2) is involved in several neurological and psychiatric disorders and is an attractive drug target. It is believed to form a strict dimer and the dimeric assembly is necessary for glutamate induced activation. Although many studies have focused on glutamate induced conformational changes, the dimerization propensity of mGluR2 with and without glutamate has never been investigated. Also, the role of the unstructured loop in dimerization of mGluR2 is not clear. Here, using Forster Resonance Energy Transfer (FRET) based assay in live cells we show that mGluR2 does not form a "strict dimer" rather it exists in a dynamic monomer-dimer equilibrium. The unstructured loop moderately destabilizes the dimers. Furthermore, binding of glutamate to mGluR2 induces conformational change that promotes monomerization of mGluR2. In the absence of an unstructured loop, mGluR2 neither undergoes conformational change nor monomerizes upon binding to glutamate.
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Affiliation(s)
- Deo R Singh
- Department of Biochemistry, Weill Cornell Medical College, NYC, NY, USA; Department of Cell and Molecular Physiology, Stritch School of Medicine, Maywood, IL, USA; Department of Oncology, University of Wisconsin, Madison, WI, USA.
| | - Kalpana Pandey
- Department of Biochemistry, Weill Cornell Medical College, NYC, NY, USA; Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India.
| | - Ashish K Mishra
- Cell and Developmental Biology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Pankaj Pandey
- Department of Zoology, Brahmanand College, Kanpur, UP, India
| | - Victor Vivcharuk
- Department of Biochemistry, Weill Cornell Medical College, NYC, NY, USA
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7
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Changes in levels of cortical metabotropic glutamate 2 receptors with gender and suicide but not psychiatric diagnoses. J Affect Disord 2019; 244:80-84. [PMID: 30326345 DOI: 10.1016/j.jad.2018.10.088] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 09/26/2018] [Accepted: 10/05/2018] [Indexed: 02/05/2023]
Abstract
BACKGROUND We previously reported that, compared to controls, there are lower levels of [3H]LY341495 binding to metabotropic 2/3 receptors (GRM2/3) in Brodmann's area (BA) 24, but not 17 or 46, from subjects with major depressive disorders (MDD) but not bipolar disorders (BD) or schizophrenia. To be able to better interpret these data we have now measured levels of GRM2 in two of these cortical regions. METHODS Using a rabbit anti-metabotropic GRM2 monoclonal antibody with Western blotting we measured levels of GRM2 in BA 24 and 46 from subjects with MDD, BD, schizophrenia and controls (n = 15 per group). RESULTS Compared to controls, levels of GRM2, normalised to β-actin, did not differ in BA 24 or 46 from subjects with MDD, BD or schizophrenia (p from 0.36 to 0.79). Levels of GRM2 in BA 46, but not BA 24, were significantly higher in males compared to females (p < 0.01) and in suicide completers (p < 0.01) compare to death by other causes. LIMITATIONS Our cohort sizes, whilst being comparable to many postmortem CNS studies, are relatively low. CONCLUSIONS Our data suggests levels of GRM2 are not altered in two cortical regions from subjects with mood disorders or schizophrenia. Given we have found lower levels of [3H]LY341495 binding to GRM2/3 in BA 24 from subjects with MDD, our new data argues the lower levels of radioligand binding was due to lower levels of GRM3. Our data also suggests that glutamatergic activity through GRM2 in BA 46 may differ with gender and suicide ideation.
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Hámor PU, Šírová J, Páleníček T, Zaniewska M, Bubeníková-Valešová V, Schwendt M. Chronic methamphetamine self-administration dysregulates 5-HT2A and mGlu2 receptor expression in the rat prefrontal and perirhinal cortex: Comparison to chronic phencyclidine and MK-801. Pharmacol Biochem Behav 2018; 175:89-100. [PMID: 30240581 PMCID: PMC6756482 DOI: 10.1016/j.pbb.2018.09.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 09/14/2018] [Accepted: 09/16/2018] [Indexed: 12/16/2022]
Abstract
Chronic methamphetamine (meth) abuse often turns into a compulsive drug-taking disorder accompanied by persistent cognitive deficits and re-occurring psychosis. Possible common neurobiological substrates underlying meth-induced deficits and schizophrenia remain poorly understood. Serotonin 2A (5-HT2A) and metabotropic glutamate 2 (mGlu2) receptors co-regulate psychosis-like behaviors and cognitive function in animals. Therefore, in the present study we examined the effects of chronic exposure to three different drugs known to produce persistent deficits in sensorimotor gating and cognition [meth, phencyclidine (PCP) and MK-801] on the expression of 5-HT2A and mGlu2 within the rat medial prefrontal cortex (mPFC), dorsal hippocampus (dHPC) and perirhinal cortex (PRh). Adult male rats underwent 14 days of: (a) meth self-administration (6 h/day), (b) phencyclidine (PCP; 5 mg/kg, twice/day) administration, or (c) MK-801 (0.3 mg/kg, twice/day) administration. Seven days after the discontinuation of drug administration, tissues of interest were collected for protein expression analysis. We found that despite different pharmacological mechanism of action, chronic meth, PCP, and MK-801 similarly dysregulated 5-HT2A and mGlu2, as indicated by an increase in the 5-HT2A/mGlu2 expression ratio in the mPFC (all three tested drugs), PRh (meth and PCP), and dHPC (MK-801 only). Complementary changes in G-protein expression (increase in Gαq and decrease in Gαi) were also observed in the mPFC of meth animals. Finally, we found that 5-HT2A/mGlu2 cooperation can be mediated in part by the formation of the receptor heteromer in some, but not all cortical regions. In summary, these data suggest that a shift towards increased availability (and G-protein coupling) of cortical 5-HT2A vs. mGlu2 receptors may represent a common neurobiological mechanism underlying the emergence of psychosis and cognitive deficits observed in subjects with meth use disorder and schizophrenia.
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Affiliation(s)
- Peter U Hámor
- Psychology Department, University of Florida, Gainesville, FL 32611, USA; Center for Addiction Research and Education (CARE) at University of Florida, USA
| | - Jana Šírová
- National Institute of Mental Health, 250 67 Klecany, Czech Republic; 3rd Faculty of Medicine, Charles University, 100 00 Prague 10, Czech Republic
| | - Tomáš Páleníček
- National Institute of Mental Health, 250 67 Klecany, Czech Republic
| | - Magdalena Zaniewska
- Laboratory of Pharmacology and Brain Biostructure, Institute of Pharmacology, Polish Academy of Sciences, Kraków, PL 31343, Poland; Molecular Biology of Peptide Hormones, Department of Cardiovascular Research, Max-Delbrück-Center for Molecular Medicine, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | | | - Marek Schwendt
- Psychology Department, University of Florida, Gainesville, FL 32611, USA; Center for Addiction Research and Education (CARE) at University of Florida, USA.
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Leurquin-Sterk G, Celen S, Van Laere K, Koole M, Bormans G, Langlois X, Van Hecken A, te Riele P, Alcázar J, Verbruggen A, de Hoon J, Andrés JI, Schmidt ME. What We Observe In Vivo Is Not Always What We See In Vitro: Development and Validation of 11C-JNJ-42491293, A Novel Radioligand for mGluR2. J Nucl Med 2016; 58:110-116. [DOI: 10.2967/jnumed.116.176628] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 07/11/2016] [Indexed: 12/13/2022] Open
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10
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Muguruza C, Meana JJ, Callado LF. Group II Metabotropic Glutamate Receptors as Targets for Novel Antipsychotic Drugs. Front Pharmacol 2016; 7:130. [PMID: 27242534 PMCID: PMC4873505 DOI: 10.3389/fphar.2016.00130] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 05/05/2016] [Indexed: 11/13/2022] Open
Abstract
Schizophrenia is a chronic psychiatric disorder which substantially impairs patients' quality of life. Despite the extensive research in this field, the pathophysiology and etiology of schizophrenia remain unknown. Different neurotransmitter systems and functional networks have been found to be affected in the brain of patients with schizophrenia. In this context, postmortem brain studies as well as genetic assays have suggested alterations in Group II metabotropic glutamate receptors (mGluRs) in schizophrenia. Despite many years of drug research, several needs in the treatment of schizophrenia have not been addressed sufficiently. In fact, only 5-10% of patients with schizophrenia successfully achieve a full recovery after treatment. In recent years mGluRs have turned up as novel targets for the design of new antipsychotic medications for schizophrenia. Concretely, Group II mGluRs are of particular interest due to their regulatory role in neurotransmission modulating glutamatergic activity in brain synapses. Preclinical studies have demonstrated that orthosteric Group II mGluR agonists exhibit antipsychotic-like properties in animal models of schizophrenia. However, when these compounds have been tested in human clinical studies with schizophrenic patients results have been inconclusive. Nevertheless, it has been recently suggested that this apparent lack of efficacy in schizophrenic patients may be related to previous exposure to atypical antipsychotics. Moreover, the role of the functional heterocomplex formed by 5-HT2A and mGlu2 receptors in the clinical response to Group II mGluR agonists is currently under study.
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Affiliation(s)
- Carolina Muguruza
- Department of Pharmacology, University of the Basque Country, UPV/EHULeioa, Spain
- Centro de Investigación Biomédica en Red de Salud MentalMadrid, Spain
| | - J. Javier Meana
- Department of Pharmacology, University of the Basque Country, UPV/EHULeioa, Spain
- Centro de Investigación Biomédica en Red de Salud MentalMadrid, Spain
| | - Luis F. Callado
- Department of Pharmacology, University of the Basque Country, UPV/EHULeioa, Spain
- Centro de Investigación Biomédica en Red de Salud MentalMadrid, Spain
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11
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In the grey zone between epilepsy and schizophrenia: alterations in group II metabotropic glutamate receptors. Acta Neurol Belg 2015; 115:221-32. [PMID: 25539775 DOI: 10.1007/s13760-014-0407-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 12/05/2014] [Indexed: 01/09/2023]
Abstract
Glutamate is the major excitatory neurotransmitter in the brain. The glutamate system plays an important role in the formation of synapses during brain development and synaptic plasticity. Dysfunctions in glutamate regulation may lead to hyperexcitatory neuronal networks and neurotoxicity. Glutamate excess is possibly of great importance in the pathophysiology of several neurological and psychiatric disorders such as epilepsy and schizophrenia. Interestingly, cross talk between these disorders has been well documented: psychiatric comorbidities are frequent in epilepsy and temporal lobe epilepsy is one of the highest risk factors for developing psychosis. Therefore, dysfunctions in glutamatergic neurotransmission might constitute a common pathological mechanism. A major negative feedback system is regulated by the presynaptic group II metabotropic glutamate (mGlu) receptors including mGlu2/3 receptors. These receptors are predominantly localised extrasynaptically in basal ganglia and limbic structures. Hence, mGlu2/3 receptors are an interesting target for the treatment of disorders like epilepsy and schizophrenia. A dysfunction in the glutamate system may be associated with alterations in mGlu2/3 receptor expression. In this review, we describe the localization of mGlu2/3 receptors in the healthy brain of mice, rats and humans. Secondly, changes in mGlu2/3 receptor density of the brain regions affected in epilepsy and schizophrenia are summarised. Increased mGlu2/3 receptor density might represent a compensatory mechanism of the brain to regulate elevated glutamate levels, while reduced mGlu2/3 receptor density in some brain regions may further contribute to the aberrant hyperexcitability. Further research considering the mGlu2/3 receptor can contribute significantly to the understanding of the etiological and therapeutic role of group II mGlu receptor in epilepsy, epilepsy with psychosis and schizophrenia.
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12
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Ellaithy A, Younkin J, González-Maeso J, Logothetis DE. Positive allosteric modulators of metabotropic glutamate 2 receptors in schizophrenia treatment. Trends Neurosci 2015; 38:506-16. [PMID: 26148747 PMCID: PMC4530036 DOI: 10.1016/j.tins.2015.06.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 06/07/2015] [Accepted: 06/11/2015] [Indexed: 12/22/2022]
Abstract
The past two decades have witnessed a rise in the 'NMDA receptor hypofunction' hypothesis for schizophrenia, a devastating disorder that affects around 1% of the population worldwide. A variety of presynaptic, postsynaptic, and regulatory proteins involved in glutamatergic signaling have thus been proposed as potential therapeutic targets. This review focuses on positive allosteric modulation of metabotropic glutamate 2 receptors (mGlu2Rs) and discusses how recent preclinical epigenetic data may provide a molecular explanation for the discrepant results of clinical studies, further stimulating the field to exploit the promise of mGlu2R as a target for schizophrenia treatment.
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Affiliation(s)
- Amr Ellaithy
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Jason Younkin
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Javier González-Maeso
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA 23298, USA; Departments of Psychiatry and Neurology, and The Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
| | - Diomedes E Logothetis
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA 23298, USA.
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13
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Pershing ML, Bortz DM, Pocivavsek A, Fredericks PJ, Jørgensen CV, Vunck SA, Leuner B, Schwarcz R, Bruno JP. Elevated levels of kynurenic acid during gestation produce neurochemical, morphological, and cognitive deficits in adulthood: implications for schizophrenia. Neuropharmacology 2015; 90:33-41. [PMID: 25446576 PMCID: PMC4731221 DOI: 10.1016/j.neuropharm.2014.10.017] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 10/17/2014] [Accepted: 10/21/2014] [Indexed: 11/16/2022]
Abstract
The levels of kynurenic acid (KYNA), an endogenous negative modulator of alpha7 nicotinic acetylcholine receptors (α7nAChRs), are elevated in the brains of patients with schizophrenia (SZ). We reported that increases of brain KYNA in rats, through dietary exposure to its precursor kynurenine from embryonic day (ED)15 to postnatal day (PD) 21, result in neurochemical and cognitive deficits in adulthood. The present experiments focused on the effects of prenatal exposure to elevated kynurenine on measures of prefrontal excitability known to be impaired in SZ. Pregnant dams were fed a mash containing kynurenine (100 mg/day; progeny = EKYNs) from ED15 until ED22. Controls were fed an unadulterated mash (progeny = ECONs). The dietary loading procedure elevated maternal and fetal plasma kynurenine (2223% and 693% above controls, respectively) and increased fetal KYNA (forebrain; 500% above controls) on ED21. Elevations in forebrain KYNA disappeared after termination of the loading (PD2), but KYNA levels in the prefrontal cortex (PFC) were unexpectedly increased again when measured in adults (PD56-80; 75% above controls). We also observed changes in several markers of prefrontal excitability, including expression of the α7nAChR (22% and 17% reductions at PD2 and PD56-80), expression of mGluR2 (31% and 24% reductions at ED21 and PD56-80), dendritic spine density (11-14% decrease at PD56-80), subsensitive mesolimbic stimulation of glutamate release in PFC, and reversal/extra-dimensional shift deficits in the prefrontally-mediated set-shifting task. These results highlight the deleterious impact of elevated KYNA levels during sensitive periods of early development, which model the pathophysiological and cognitive deficits seen in SZ.
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Affiliation(s)
| | - David M Bortz
- Department of Psychology, The Ohio State University, Columbus, OH, USA
| | - Ana Pocivavsek
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland College of Medicine, Baltimore, MD, USA
| | | | | | - Sarah A Vunck
- Department of Psychology, The Ohio State University, Columbus, OH, USA
| | - Benedetta Leuner
- Department of Psychology, The Ohio State University, Columbus, OH, USA; Department of Neuroscience, The Ohio State University, Columbus, OH, USA
| | - Robert Schwarcz
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland College of Medicine, Baltimore, MD, USA
| | - John P Bruno
- Department of Psychology, The Ohio State University, Columbus, OH, USA; Department of Neuroscience, The Ohio State University, Columbus, OH, USA.
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14
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Metabotropic glutamate receptor 3 activation is required for long-term depression in medial prefrontal cortex and fear extinction. Proc Natl Acad Sci U S A 2015; 112:1196-201. [PMID: 25583490 DOI: 10.1073/pnas.1416196112] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Clinical studies have revealed that genetic variations in metabotropic glutamate receptor 3 (mGlu3) affect performance on cognitive tasks dependent upon the prefrontal cortex (PFC) and may be linked to psychiatric conditions such as schizophrenia, bipolar disorder, and addiction. We have performed a series of studies aimed at understanding how mGlu3 influences PFC function and cognitive behaviors. In the present study, we found that activation of mGlu3 can induce long-term depression in the mouse medial PFC (mPFC) in vitro. Furthermore, in vivo administration of a selective mGlu3 negative allosteric modulator impaired learning in the mPFC-dependent fear extinction task. The results of these studies implicate mGlu3 as a major regulator of PFC function and cognition. Additionally, potentiators of mGlu3 may be useful in alleviating prefrontal impairments associated with several CNS disorders.
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15
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Hu W, MacDonald ML, Elswick DE, Sweet RA. The glutamate hypothesis of schizophrenia: evidence from human brain tissue studies. Ann N Y Acad Sci 2014; 1338:38-57. [PMID: 25315318 DOI: 10.1111/nyas.12547] [Citation(s) in RCA: 169] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A number of studies have indicated that antagonists of the N-methyl-d-aspartate subtypes of glutamate receptors can cause schizophrenia-like symptoms in healthy individuals and exacerbate symptoms in individuals with schizophrenia. These findings have led to the glutamate hypothesis of schizophrenia. Here we review the evidence for this hypothesis in postmortem studies of brain tissue from individuals affected by schizophrenia, summarizing studies of glutamate neuron morphology, of expression of glutamate receptors and transporters, and of the synthesizing and metabolizing enzymes for glutamate and its co-agonists. We found consistent evidence of morphological alterations of dendrites of glutamatergic neurons in the cerebral cortex of subjects with schizophrenia and of reduced levels of the axon bouton marker synaptophysin. There were no consistent alterations of mRNA expression of glutamate receptors, although there has been limited study of the corresponding proteins. Studies of the glutamate metabolic pathway have been limited, although there is some evidence that excitatory amino acid transporter-2, glutamine synthetase, and glutaminase have altered expression in schizophrenia. Future studies would benefit from additional direct examination of glutamatergic proteins. Further advances, such as selective testing of synaptic microdomains, cortical layers, and neuronal subtypes, may also be required to elucidate the nature of glutamate signaling impairments in schizophrenia.
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Affiliation(s)
- Wei Hu
- Department of Behavioral Medicine and Psychiatry, West Virginia University Health Sciences Center, Morgantown, West Virginia
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Pomierny-Chamioło L, Rup K, Pomierny B, Niedzielska E, Kalivas PW, Filip M. Metabotropic glutamatergic receptors and their ligands in drug addiction. Pharmacol Ther 2014; 142:281-305. [DOI: 10.1016/j.pharmthera.2013.12.012] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 12/02/2013] [Indexed: 02/07/2023]
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Iasevoli F, Tomasetti C, Buonaguro EF, de Bartolomeis A. The glutamatergic aspects of schizophrenia molecular pathophysiology: role of the postsynaptic density, and implications for treatment. Curr Neuropharmacol 2014; 12:219-38. [PMID: 24851087 PMCID: PMC4023453 DOI: 10.2174/1570159x12666140324183406] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 02/14/2014] [Accepted: 03/14/2014] [Indexed: 01/23/2023] Open
Abstract
Schizophrenia is one of the most debilitating psychiatric diseases with a lifetime prevalence of approximately
1%. Although the specific molecular underpinnings of schizophrenia are still unknown, evidence has long linked its
pathophysiology to postsynaptic abnormalities.
The postsynaptic density (PSD) is among the molecular structures suggested to be potentially involved in schizophrenia.
More specifically, the PSD is an electron-dense thickening of glutamatergic synapses, including ionotropic and
metabotropic glutamate receptors, cytoskeletal and scaffolding proteins, and adhesion and signaling molecules. Being
implicated in the postsynaptic signaling of multiple neurotransmitter systems, mostly dopamine and glutamate, the PSD
constitutes an ideal candidate for studying dopamine-glutamate disturbances in schizophrenia. Recent evidence suggests
that some PSD proteins, such as PSD-95, Shank, and Homer are implicated in severe behavioral disorders, including
schizophrenia. These findings, further corroborated by genetic and animal studies of schizophrenia, offer new insights for
the development of pharmacological strategies able to overcome the limitations in terms of efficacy and side effects of
current schizophrenia treatment. Indeed, PSD proteins are now being considered as potential molecular targets against this
devastating illness.
The current paper reviews the most recent hypotheses on the molecular mechanisms underlying schizophrenia
pathophysiology. First, we review glutamatergic dysfunctions in schizophrenia and we provide an update on postsynaptic
molecules involvement in schizophrenia pathophysiology by addressing both human and animal studies. Finally, the
possibility that PSD proteins may represent potential targets for new molecular interventions in psychosis will be
discussed.
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Affiliation(s)
- Felice Iasevoli
- Department of Neuroscience, Reproductive and Odontostomatological Sciences - University "Federico II", Naples, Italy
| | - Carmine Tomasetti
- Department of Neuroscience, Reproductive and Odontostomatological Sciences - University "Federico II", Naples, Italy
| | - Elisabetta F Buonaguro
- Department of Neuroscience, Reproductive and Odontostomatological Sciences - University "Federico II", Naples, Italy
| | - Andrea de Bartolomeis
- Department of Neuroscience, Reproductive and Odontostomatological Sciences - University "Federico II", Naples, Italy
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18
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Rubio MD, Drummond JB, Meador-Woodruff JH. Glutamate receptor abnormalities in schizophrenia: implications for innovative treatments. Biomol Ther (Seoul) 2014; 20:1-18. [PMID: 24116269 PMCID: PMC3792192 DOI: 10.4062/biomolther.2012.20.1.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 11/25/2011] [Indexed: 01/18/2023] Open
Abstract
Schizophrenia is a devastating psychiatric illness that afflicts 1% of the population worldwide, resulting in substantial impact to patients, their families, and health care delivery systems. For many years, schizophrenia has been felt to be associated with dysregulated dopaminergic neurotransmission as a key feature of the pathophysiology of the illness. Although numerous studies point to dopaminergic abnormalities in schizophrenia, dopamine dysfunction cannot completely account for all of the symptoms seen in schizophrenia, and dopamine-based treatments are often inadequate and can be associated with serious side effects. More recently, converging lines of evidence have suggested that there are abnormalities of glutamate transmission in schizophrenia. Glutamatergic neurotransmission involves numerous molecules that facilitate glutamate release, receptor activation, glutamate reuptake, and other synaptic activities. Evidence for glutamatergic abnormalities in schizophrenia primarily has implicated the NMDA and AMPA subtypes of the glutamate receptor. The expression of these receptors and other molecules associated with glutamate neurotransmission has been systematically studied in the brain in schizophrenia. These studies have generally revealed region- and molecule-specific changes in glutamate receptor transcript and protein expression in this illness. Given that glutamatergic neurotransmission has been implicated in the pathophysiology of schizophrenia, recent drug development efforts have targeted the glutamate system. Much effort to date has focused on modulation of the NMDA receptor, although more recently other glutamate receptors and transporters have been the targets of drug development. These efforts have been promising thus far, and ongoing efforts to develop additional drugs that modulate glutamatergic neurotransmission are underway that may hold the potential for novel classes of more effective treatments for this serious psychiatric illness.
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Affiliation(s)
- Maria D Rubio
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294-0021, USA
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19
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Arey RN, Enwright JF, Spencer SM, Falcon E, Ozburn AR, Ghose S, Tamminga C, McClung CA. An important role for cholecystokinin, a CLOCK target gene, in the development and treatment of manic-like behaviors. Mol Psychiatry 2014; 19:342-50. [PMID: 23399917 PMCID: PMC3783638 DOI: 10.1038/mp.2013.12] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Revised: 12/17/2012] [Accepted: 01/02/2013] [Indexed: 01/31/2023]
Abstract
Mice with a mutation in the Clock gene (ClockΔ19) have been identified as a model of mania; however, the mechanisms that underlie this phenotype, and the changes in the brain that are necessary for lithium's effectiveness on these mice remain unclear. Here, we find that cholecystokinin (Cck) is a direct transcriptional target of CLOCK and levels of Cck are reduced in the ventral tegmental area (VTA) of ClockΔ19 mice. Selective knockdown of Cck expression via RNA interference in the VTA of wild-type mice produces a manic-like phenotype. Moreover, chronic treatment with lithium restores Cck expression to near wild-type and this increase is necessary for the therapeutic actions of lithium. The decrease in Cck expression in the ClockΔ19 mice appears to be due to a lack of interaction with the histone methyltransferase, MLL1, resulting in decreased histone H3K4me3 and gene transcription, an effect reversed by lithium. Human postmortem tissue from bipolar subjects reveals a similar increase in Cck expression in the VTA with mood stabilizer treatment. These studies identify a key role for Cck in the development and treatment of mania, and describe some of the molecular mechanisms by which lithium may act as an effective antimanic agent.
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Affiliation(s)
- Rachel N. Arey
- University of Texas Southwestern Medical Center, Department of Psychiatry, Dallas, TX 75390-9070
| | - John F. Enwright
- Austin College, Department of Biology, Sherman, TX 75090,University of Pittsburgh School of Medicine, Department of Psychiatry and Translational Neuroscience Program, Pittsburgh, PA 15219
| | - Sade M. Spencer
- University of Texas Southwestern Medical Center, Department of Psychiatry, Dallas, TX 75390-9070
| | - Edgardo Falcon
- University of Texas Southwestern Medical Center, Department of Psychiatry, Dallas, TX 75390-9070
| | - Angela R. Ozburn
- University of Texas Southwestern Medical Center, Department of Psychiatry, Dallas, TX 75390-9070,University of Pittsburgh School of Medicine, Department of Psychiatry and Translational Neuroscience Program, Pittsburgh, PA 15219
| | - Subroto Ghose
- University of Texas Southwestern Medical Center, Department of Psychiatry, Dallas, TX 75390-9070
| | - Carol Tamminga
- University of Texas Southwestern Medical Center, Department of Psychiatry, Dallas, TX 75390-9070
| | - Colleen A. McClung
- University of Texas Southwestern Medical Center, Department of Psychiatry, Dallas, TX 75390-9070,University of Pittsburgh School of Medicine, Department of Psychiatry and Translational Neuroscience Program, Pittsburgh, PA 15219,Author to whom correspondence should be addressed, Colleen A. McClung, Ph.D., University of Pittsburgh School of Medicine, Department of Psychiatry, 450 Technology Drive, Suite 223, Pittsburgh, PA 15219, (412) 624-5547 phone,
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20
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Uehara T, Sumiyoshi T, Rujescu D, Genius J, Matsuoka T, Takasaki I, Itoh H, Kurachi M. Neonatal exposure to MK-801 reduces mRNA expression of mGlu3 receptors in the medial prefrontal cortex of adolescent rats. Synapse 2014; 68:202-8. [PMID: 24549941 DOI: 10.1002/syn.21734] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Accepted: 01/09/2014] [Indexed: 11/09/2022]
Abstract
Schizophrenia is considered as a "neurodegenerative" and "neurodevelopmental" disorder, the pathophysiology of which may include hypofunction of the N-methyl-D-aspartate receptor (NMDA-R) or subsequent pathways. Accordingly, administration of NMDA-R antagonists to rodents during the perinatal period may emulate some core pathophysiological aspects of schizophrenia. The effect of 4-day (postnatal day; PD 7-10) administration of MK-801, a selective NMDA-R antagonist, on gene expression in the medial prefrontal cortex (mPFC), hippocampus, and amygdala was evaluated using quantitative polymerase chain reaction methods. Specifically, we sought to determine whether genes related to Glu transmissions, for example those encoding for NMDA-Rs, metabotropic Glu receptors (mGluRs), or Glu transporters, were altered by neonatal treatment with MK-801. Model rats showed downregulation of the mGluR3 subtype in the mPFC around puberty, especially at PD 35 in response to MK-801 or during ontogenesis without pharmacological manipulations. Genes encoding for other mGluRs subtypes, that is NMDA-Rs and Glu transporters, were not affected by the neonatal insult. These results suggest that NMDA-R antagonism in the early course of development modulates the expression of mGluR3 in mPFC around puberty. Thus, mGluR3 may serve as a potential target to prevent the onset and progression of schizophrenia.
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Affiliation(s)
- Takashi Uehara
- Department of Neuropsychiatry, University of Toyama Graduate School of Medicine and Pharmaceutical Sciences, Toyama, Japan
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Abstract
One of the oldest models of schizophrenia is based on the effects of serotonergic hallucinogens such as mescaline, psilocybin, and (+)-lysergic acid diethylamide (LSD), which act through the serotonin 5-HT(2A) receptor. These compounds produce a 'model psychosis' in normal individuals that resembles at least some of the positive symptoms of schizophrenia. Based on these similarities, and because evidence has emerged that the serotonergic system plays a role in the pathogenesis of schizophrenia in some patients, animal models relevant to schizophrenia have been developed based on hallucinogen effects. Here we review the behavioural effects of hallucinogens in four of those models, the receptor and neurochemical mechanisms for the effects and their translational relevance. Despite the difficulty of modelling hallucinogen effects in nonverbal species, animal models of schizophrenia based on hallucinogens have yielded important insights into the linkage between 5-HT and schizophrenia and have helped to identify receptor targets and interactions that could be exploited in the development of new therapeutic agents.
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Delille HK, Mezler M, Marek GJ. The two faces of the pharmacological interaction of mGlu2 and 5-HT₂A - relevance of receptor heterocomplexes and interaction through functional brain pathways. Neuropharmacology 2013; 70:296-305. [PMID: 23466331 DOI: 10.1016/j.neuropharm.2013.02.005] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 02/01/2013] [Accepted: 02/04/2013] [Indexed: 11/28/2022]
Abstract
Important functional interactions between the metabotropic glutamate 2 (mGlu2) and 5-hydroxytryptamine2A (5-HT₂A) neurotransmitter receptors have been established based on electrophysiological, biochemical and behavioral evidence. Over the last several years, dimerization between 5-HT₂A and mGlu2 receptors has been proposed to account for the functional cross-talk between these two receptors in the prefrontal cortex. The pros and cons for the existence of a heteromeric complex between 5-HT₂A and mGlu2 receptors will be reviewed here. First, the fundamental criteria needing to establish evidence for heteromeric complexes will be reviewed. Then, the in vitro evidence for and against heteromeric complexes between 5-HT₂A and mGlu2 receptors will be discussed in regard to physical and functional interactions. Finally, the data with native in situ mGlu2 and 5-HT₂A receptors will be discussed with respect to whether heteromeric complexes or a simple functional interaction between two distinct GPCRs based on brain network activity is the more simple explanation for a range of in vivo data.
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Affiliation(s)
- Hannah K Delille
- Abbott Diagnostics Division, Max-Planck-Ring 2, 65205 Wiesbaden, Germany
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23
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Hovelsø N, Sotty F, Montezinho LP, Pinheiro PS, Herrik KF, Mørk A. Therapeutic potential of metabotropic glutamate receptor modulators. Curr Neuropharmacol 2012; 10:12-48. [PMID: 22942876 PMCID: PMC3286844 DOI: 10.2174/157015912799362805] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2010] [Revised: 01/10/2011] [Accepted: 03/04/2011] [Indexed: 12/21/2022] Open
Abstract
Glutamate is the main excitatory neurotransmitter in the central nervous system (CNS) and is a major player in complex brain functions. Glutamatergic transmission is primarily mediated by ionotropic glutamate receptors, which include NMDA, AMPA and kainate receptors. However, glutamate exerts modulatory actions through a family of metabotropic G-protein-coupled glutamate receptors (mGluRs). Dysfunctions of glutamatergic neurotransmission have been implicated in the etiology of several diseases. Therefore, pharmacological modulation of ionotropic glutamate receptors has been widely investigated as a potential therapeutic strategy for the treatment of several disorders associated with glutamatergic dysfunction. However, blockade of ionotropic glutamate receptors might be accompanied by severe side effects due to their vital role in many important physiological functions. A different strategy aimed at pharmacologically interfering with mGluR function has recently gained interest. Many subtype selective agonists and antagonists have been identified and widely used in preclinical studies as an attempt to elucidate the role of specific mGluRs subtypes in glutamatergic transmission. These studies have allowed linkage between specific subtypes and various physiological functions and more importantly to pathological states. This article reviews the currently available knowledge regarding the therapeutic potential of targeting mGluRs in the treatment of several CNS disorders, including schizophrenia, addiction, major depressive disorder and anxiety, Fragile X Syndrome, Parkinson’s disease, Alzheimer’s disease and pain.
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Affiliation(s)
- N Hovelsø
- Department of Neurophysiology, H. Lundbeck A/S, Ottiliavej 9, 2500 Copenhagen-Valby, Denmark
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24
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Sutton LP, Rushlow WJ. Regulation of Akt and Wnt signaling by the group II metabotropic glutamate receptor antagonist LY341495 and agonist LY379268. J Neurochem 2011; 117:973-83. [PMID: 21477044 DOI: 10.1111/j.1471-4159.2011.07268.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Metabotropic glutamate receptors 2/3 (mGlu(2/3)) have been implicated in schizophrenia and as a novel treatment target for schizophrenia. The current study examined whether mGlu(2/3) regulates Akt (protein kinase B) and Wnt (Wingless/Int-1) signaling, two cascades associated with schizophrenia and modified by antipsychotics. Western blotting revealed increases in phosphorylated Akt (pAkt) and phosphorylated glycogen synthase kinase-3 (pGSK-3) following acute and repeated treatment of LY379268 (mGlu(2/3) agonist), whereas increases in dishevelled-2 (Dvl-2), dishevelled-3 (Dvl-3), GSK-3 and β-catenin were only observed following repeated treatment. LY341495 (mGlu(2/3) antagonist) induced the opposite response compared with LY379268. Co-immunoprecipitation experiments showed an association between the mGlu(2/3) complex and Dvl-2 providing a possible mechanism to explain how the mGlu(2/3) can mediate changes in Wnt signaling. However, there was no association between the mGlu(2/3) complex and Akt suggesting that changes in Akt signaling following LY341495 and LY379268 treatments may not be directly mediated by the mGlu(2/3) . Finally, an increase in locomotor activity induced by LY341495 treatment correlated with increased pAkt and pGSK-3 levels and was attenuated by the administration of the GSK-3 inhibitor, SB216763. Overall, the results suggest that mGlu(2/3) regulates Akt and Wnt signaling and LY379268 treatment has overlapping effects with D(2) dopamine receptor antagonists (antipsychotic drugs).
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Affiliation(s)
- Laurie P Sutton
- Department of Anatomy & Cell Biology, University of Western Ontario and the London Health Sciences Centre, London, Ontario, Canada
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25
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Jones CA, Brown AM, Auer DP, Fone KCF. The mGluR2/3 agonist LY379268 reverses post-weaning social isolation-induced recognition memory deficits in the rat. Psychopharmacology (Berl) 2011; 214:269-83. [PMID: 20607219 DOI: 10.1007/s00213-010-1931-7] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Accepted: 06/22/2010] [Indexed: 01/31/2023]
Abstract
RATIONALE Current antipsychotics are ineffective at treating the negative and cognitive symptoms of schizophrenia, so there is a substantial need to develop more effective therapeutics for this debilitating disorder. The type II metabotropic glutamate receptor (mGluR2/3) is a novel, potential therapeutic target requiring evaluation in appropriate preclinical models of schizophrenia. OBJECTIVE This study evaluated the potent, selective mGluR2/3 agonist, LY379268, on the behavioural deficits induced by rearing rat pups in social isolation from weaning, a neurodevelopmental model of schizophrenia, to investigate its antipsychotic potential. METHODS Male Lister Hooded rats were weaned on post-natal day 23-25 and either group-housed (3-4 per cage) or isolation-reared for 6 weeks. At subsequent weekly intervals, animals received acute systemic injection of either vehicle or LY379268 (1 mg/kg; i.p.) 30 min prior to recording locomotor activity in a novel arena, novel object recognition, pre-pulse inhibition of acoustic startle and conditioned emotional response paradigms. RESULTS Isolation rearing induced locomotor hyperactivity, deficits in novel object recognition, conditioned emotional behaviour and attenuated the magnitude of the initial acoustic startle response in the PPI paradigm compared to that of group-housed controls. LY379268 reversed the isolation-induced locomotor hyperactivity, the object recognition deficit, and restored startle responses in isolated animals, whilst having no effect on conditioned emotional response impairments. CONCLUSIONS These data show that LY379268 can reverse some, but not all, post-weaning social isolation-induced changes which have translational relevance to core symptom defects in schizophrenia and support a potential therapeutic role of mGluR2/3 agonists in its treatment.
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Affiliation(s)
- Caitlin A Jones
- School of Biomedical Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, NG7 2UH, UK
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26
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Metabotropic glutamate2/3 (mGlu2/3) receptors, schizophrenia and cognition. Eur J Pharmacol 2010; 639:81-90. [PMID: 20371229 DOI: 10.1016/j.ejphar.2010.02.058] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Revised: 01/19/2010] [Accepted: 02/04/2010] [Indexed: 10/19/2022]
Abstract
Recently, a metabotropic glutamate(2/3) (mGlu(2/3)) receptor agonist prodrug was found to improve both the positive and negative symptoms of schizophrenic patients. Thus far, however, definitive data directly describing the effects of mGlu(2/3) receptor agonists on cognition in schizophrenic patients is lacking. In this review, we will first describe the location of mGlu(2) and mGlu(3) receptors with respect to cellular compartments in cortical circuits of both the prefrontal cortex and the hippocampal formation. We will then address the function of mGlu(2) and mGlu(3) receptors in both macrocircuits and microcircuits involving the prefrontal cortex and hippocampal formation. Imbalance within and between macrocircuits, including the re-entrant cortico-striatal-thalamic loops; the trisynaptic organization of the hippocampal formation; and the ascending reticular activating system/monoaminergic brainstem nuclei projecting throughout the neural axis, appear central to understanding both the pathophysiology and therapeutic approaches for treating the pervasive cognitive dysfunction associated with schizophrenia. Understanding the function of mGlu(2) and mGlu(3) receptors in these macrocircuits also may provide answers to currently conflicting data between some preclinical studies and the clinical studies seemingly predicting impairment and improvement in cognitive function with activation of mGlu(2) and mGlu(3) receptors.
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Cherlyn SYT, Woon PS, Liu JJ, Ong WY, Tsai GC, Sim K. Genetic association studies of glutamate, GABA and related genes in schizophrenia and bipolar disorder: a decade of advance. Neurosci Biobehav Rev 2010; 34:958-77. [PMID: 20060416 DOI: 10.1016/j.neubiorev.2010.01.002] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Revised: 01/01/2010] [Accepted: 01/04/2010] [Indexed: 12/31/2022]
Abstract
Schizophrenia (SZ) and bipolar disorder (BD) are debilitating neurobehavioural disorders likely influenced by genetic and non-genetic factors and which can be seen as complex disorders of synaptic neurotransmission. The glutamatergic and GABAergic neurotransmission systems have been implicated in both diseases and we have reviewed extensive literature over a decade for evidence to support the association of glutamate and GABA genes in SZ and BD. Candidate-gene based population and family association studies have implicated some ionotrophic glutamate receptor genes (GRIN1, GRIN2A, GRIN2B and GRIK3), metabotropic glutamate receptor genes (such as GRM3), the G72/G30 locus and GABAergic genes (e.g. GAD1 and GABRB2) in both illnesses to varying degrees, but further replication studies are needed to validate these results. There is at present no consensus on specific single nucleotide polymorphisms or haplotypes associated with the particular candidate gene loci in these illnesses. The genetic architecture of glutamate systems in bipolar disorder need to be better studied in view of recent data suggesting an overlap in the genetic aetiology of SZ and BD. There is a pressing need to integrate research platforms in genomics, epistatic models, proteomics, metabolomics, neuroimaging technology and translational studies in order to allow a more integrated understanding of glutamate and GABAergic signalling processes and aberrations in SZ and BD as well as their relationships with clinical presentations and treatment progress over time.
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Affiliation(s)
- Suat Ying Tan Cherlyn
- Institute of Mental Health/Woodbridge Hospital, 10 Buangkok View, Singapore 539747, Singapore
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28
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Moreno JL, Sealfon SC, González-Maeso J. Group II metabotropic glutamate receptors and schizophrenia. Cell Mol Life Sci 2009; 66:3777-85. [PMID: 19707855 PMCID: PMC2792875 DOI: 10.1007/s00018-009-0130-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Revised: 07/10/2009] [Accepted: 08/11/2009] [Indexed: 12/18/2022]
Abstract
Schizophrenia is one of the most common mental illnesses, with hereditary and environmental factors important for its etiology. All antipsychotics have in common a high affinity for monoaminergic receptors. Whereas hallucinations and delusions usually respond to typical (haloperidol-like) and atypical (clozapine-like) monoaminergic antipsychotics, their efficacy in improving negative symptoms and cognitive deficits remains inadequate. In addition, devastating side effects are a common characteristic of monoaminergic antipsychotics. Recent biochemical, preclinical and clinical findings support group II metabotropic glutamate receptors (mGluR2 and mGluR3) as a new approach to treat schizophrenia. This paper reviews the status of general knowledge of mGluR2 and mGluR3 in the psychopharmacology, genetics and neuropathology of schizophrenia.
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Affiliation(s)
- José L. Moreno
- Department of Psychiatry, Mount Sinai School of Medicine, New York, NY 10029 USA
- Division of Basic Neuroscience, Mount Sinai School of Medicine, New York, NY 10029 USA
| | - Stuart C. Sealfon
- Department of Neurology, Mount Sinai School of Medicine, New York, NY 10029 USA
- Center for Translational Systems Biology, Mount Sinai School of Medicine, New York, NY 10029 USA
| | - Javier González-Maeso
- Department of Psychiatry, Mount Sinai School of Medicine, New York, NY 10029 USA
- Department of Neurology, Mount Sinai School of Medicine, New York, NY 10029 USA
- Division of Basic Neuroscience, Mount Sinai School of Medicine, New York, NY 10029 USA
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29
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Ghose S, Gleason KA, Potts BW, Lewis-Amezcua K, Tamminga CA. Differential expression of metabotropic glutamate receptors 2 and 3 in schizophrenia: a mechanism for antipsychotic drug action? Am J Psychiatry 2009; 166:812-20. [PMID: 19487395 PMCID: PMC2860261 DOI: 10.1176/appi.ajp.2009.08091445] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Preclinical and clinical data implicate the group II metabotropic glutamate receptors mGluR2 and mGluR3 in the pathophysiology of schizophrenia. Moreover, a recent phase II clinical trial demonstrated the antipsychotic efficacy of a mGluR2/mGluR3 agonist. The purpose of the present study was to distinguish the expression of mGluR2 and mGluR3 receptor proteins in schizophrenia and to quantify glutamate carboxypeptidase II (GCP II) in order to explore a role for the metabotropic receptors in schizophrenia therapeutics. GCP II is an enzyme that metabolizes N-acetyl-aspartyl-glutamate (NAAG), which is the only known specific endogenous agonist of mGluR3 in the mammalian brain. METHOD The normal expression levels of mGluR2, mGluR3, and GCP II were determined for 10 regions of the postmortem human brain using specific antibodies. Differences in expression levels of each protein were examined in the dorsolateral prefrontal cortex, temporal cortex, and motor cortex in 15 postmortem schizophrenia subjects and 15 postmortem matched normal comparison subjects. Chronic antipsychotic treatment in rodents was conducted to examine the potential effect of antipsychotic drugs on expression of the three proteins. RESULTS Findings revealed a significant increase in GCP II protein and a reduction in mGluR3 protein in the dorsolateral prefrontal cortex in schizophrenia subjects, with mGluR2 protein levels unchanged. Chronic antipsychotic treatment in rodents did not influence GCP II or mGluR3 levels. CONCLUSIONS Increased GCP II expression and low mGluR3 expression in the dorsolateral prefrontal cortex suggest that NAAG-mediated signaling is impaired in this brain region in schizophrenia. Further, these data implicate the mGluR3 receptor in the antipsychotic action of mGluR2/mGluR3 agonists.
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Affiliation(s)
- Subroto Ghose
- University of Texas Southwestern Medical Center, NE5.110C, Dallas, TX 75390-9127, USA.
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30
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Ghose S, Chin R, Gallegos A, Roberts R, Coyle J, Tamminga C. Localization of NAAG-related gene expression deficits to the anterior hippocampus in schizophrenia. Schizophr Res 2009; 111:131-7. [PMID: 19403271 PMCID: PMC2685203 DOI: 10.1016/j.schres.2009.03.038] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Revised: 03/27/2009] [Accepted: 03/30/2009] [Indexed: 10/20/2022]
Abstract
N-acetyl aspartyl glutamate (NAAG) is an endogenous agonist at the metabotropic glutamate receptor 3 (mGluR3,GRM3) receptor and antagonist at the N-methyl d-aspartate (NMDA) receptor, both receptors important to the pathophysiology of schizophrenia. Glutamate carboxypeptidase II (GCPII), an enzyme that metabolizes NAAG, is also implicated in this illness. In this study, we conducted in situ hybridization experiments to examine expression of mGluR3 and GCPII transcripts along the rostrocaudal axis of the human postmortem hippocampus. We hypothesized that we would find changes in mGluR3 and/or GCPII in the AH but not posterior hippocampus (PH) in schizophrenia. We compared mRNA levels of these genes in the dentate gyrus (DG) and cornu ammonis (CA)1 and CA3 of AH and PH in 20 matched pairs of control and schizophrenia cases. In controls, mGluR3 is highly expressed in the DG and at lower levels in CA1 and CA3 while GCP II is expressed at similar levels in these regions. Group comparisons show a significant reduction of GCPII mRNA level in the AH in schizophrenia. Post hoc analyses reveal this difference is localized to the CA1 region. In addition, we find a significant positive correlation between GCPII and mGluR3 mRNA in the CA3 of the control AH (r=0.66, p=0.008) which is not present in schizophrenia (r=0.096, p=0.76). This may reflect a disrupted functional interaction between NAAG and mGluR3 in CA3 in schizophrenia. These data suggest that NAAG-mediated signaling is disrupted in the AH in schizophrenia and localize the defect to the CA1 and CA3 regions.
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Affiliation(s)
- Subroto Ghose
- University of Texas Southwestern Medical Center, Dallas, TX 75390-9127, USA.
| | - Ronald Chin
- 5323 Harry Hines Boulevard, NE5. 110, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Analysa Gallegos
- 5323 Harry Hines Boulevard, NE5. 110, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Rosalinda Roberts
- Maryland Psychiatric Research Center, 55 Wade Avenue, Catonsville, MD, USA
| | - Joseph Coyle
- 115 Mill Street, Belmont, MA Mclean Hospital, Harvard Medical School, MA, USA
| | - Carol Tamminga
- 5323 Harry Hines Boulevard, NE5. 110, University of Texas Southwestern Medical Center, Dallas, TX, USA
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