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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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Mao LM, Mathur N, Wang JQ. An allosteric potentiator of metabotropic glutamate (mGlu) 2 receptors reduces the cocaine-stimulated ERK1/2 phosphorylation in the mouse striatum. Neurosci Lett 2023; 795:137028. [PMID: 36565803 PMCID: PMC9870709 DOI: 10.1016/j.neulet.2022.137028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 11/20/2022] [Accepted: 12/18/2022] [Indexed: 12/24/2022]
Abstract
Metabotropic glutamate (mGlu) receptors are involved in the experience-dependent neuroplasticity in the mesolimbic reward circuit. A Gαi/o-coupled mGlu2 subtype is distributed presynaptically in the striatum. These autoreceptors may have a significant influence over striatal neurons in their intracellular signaling pathways in response to a psychostimulant. Here we explored the effect of pharmacological potentiation of mGlu2 receptors on cocaine-stimulated phosphorylation (activation) of extracellular signal-regulated kinases (ERK) in the mouse striatum in vivo. We found that an mGlu2 selective positive allosteric modulator (PAM) LY487379 after a systemic injection did not alter basal phosphorylation of ERK1/2 or c-Jun N-terminal kinases in the striatum. However, pretreatment with LY487379 blocked the ERK1/2 phosphorylation induced by cocaine in the two subdivisions of the striatum, i.e., the caudate putamen and nucleus accumbens. LY487379 also blocked the cocaine-induced phosphorylation of Elk-1, a transcription factor downstream to the ERK pathway. Additionally, LY487379 reduced locomotor behavioral responses to cocaine. These results demonstrate that the mGlu2 PAM LY487379 possesses the ability to attenuate the activation of the ERK1/2 pathway in striatal neurons and reduce locomotor activity in response to cocaine in vivo.
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Affiliation(s)
- Li-Min Mao
- Department of Biomedical Sciences, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA
| | - Nirav Mathur
- Department of Anesthesiology, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA
| | - John Q Wang
- Department of Biomedical Sciences, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA; Department of Anesthesiology, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA.
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3
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Tyler RE, Besheer J, Joffe ME. Advances in translating mGlu 2 and mGlu 3 receptor selective allosteric modulators as breakthrough treatments for affective disorders and alcohol use disorder. Pharmacol Biochem Behav 2022; 219:173450. [PMID: 35988792 PMCID: PMC10405528 DOI: 10.1016/j.pbb.2022.173450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 07/26/2022] [Accepted: 08/13/2022] [Indexed: 11/16/2022]
Abstract
Metabotropic glutamate (mGlu) receptors are promising targets for the treatment of affective disorders and alcohol use disorder (AUD). Nonspecific ligands for Group II (mGlu2 and mGlu3) mGlu receptors have demonstrated consistent therapeutic potential for affective disorders in preclinical models. Disentangling the specific roles of mGlu2 versus mGlu3 receptors in these effects has persisted as a major challenge, in part due to pharmacological limitations. However, the recent development of highly specific allosteric modulators for both mGlu2 and mGlu3 receptors have enabled straightforward and rigorous investigations into the specific function of each receptor. Here, we review recent experiments using these compounds that have demonstrated both similar and distinct receptor functions in behavioral, molecular, and electrophysiological measures associated with basal function and preclinical models of affective disorders. Studies using these selective drugs have demonstrated that mGlu2 is the predominant receptor subclass involved in presynaptic neurotransmitter release in prefrontal cortex. By contrast, the activation of postsynaptic mGlu3 receptors induces a cascade of cellular changes that results in AMPA receptor internalization, producing long-term depression and diminishing excitatory drive. Acute stress decreases the mGlu3 receptor function and dynamically alters transcript expression for both mGlu2 (Grm2) and mGlu3 (Grm3) receptors in brain areas involved in reward and stress. Accordingly, both mGlu2 and mGlu3 negative allosteric modulators show acute antidepressant-like effects and potential prophylactic effects against acute and traumatic stressors. The wide array of effects displayed by these new allosteric modulators of mGlu2 and mGlu3 receptors suggest that these drugs may act through improving endophenotypes of symptoms observed across several neuropsychiatric disorders. Therefore, recently developed allosteric modulators selective for mGlu2 or mGlu3 receptors show promise as potential therapeutics for affective disorders and AUD.
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Affiliation(s)
- Ryan E Tyler
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA; Neuroscience Curriculum, University of North Carolina at Chapel Hill, USA; Department of Psychiatry, University of North Carolina at Chapel Hill, USA
| | - Joyce Besheer
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA; Neuroscience Curriculum, University of North Carolina at Chapel Hill, USA; Department of Psychiatry, University of North Carolina at Chapel Hill, USA
| | - Max E Joffe
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15219, USA; Translational Neuroscience Program, University of Pittsburgh, USA.
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Lalo U, Koh W, Lee CJ, Pankratov Y. The tripartite glutamatergic synapse. Neuropharmacology 2021; 199:108758. [PMID: 34433089 DOI: 10.1016/j.neuropharm.2021.108758] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 07/25/2021] [Accepted: 08/20/2021] [Indexed: 12/31/2022]
Abstract
Astroglial cells were long considered as structural and metabolic supporting cells are which do not directly participate in information processing in the brain. Discoveries of responsiveness of astrocytes to synaptically-released glutamate and their capability to release agonists of glutamate receptors awakened extensive studies of glia-neuron communications and led to the revolutionary changes in our understanding of brain cellular networks. Nowadays, astrocytes are widely acknowledged as inseparable element of glutamatergic synapses and role for glutamatergic astrocyte-neuron interactions in the brain computation is emerging. Astroglial glutamate receptors, in particular of NMDA, mGluR3 and mGluR5 types, can activate a variety of molecular cascades leading astroglial-driven modulation of extracellular levels of glutamate and activity of neuronal glutamate receptors. Their preferential location to the astroglial perisynaptic processes facilitates interaction of astrocytes with individual excitatory synapses. Bi-directional glutamatergic communication between astrocytes and neurons underpins a complex, spatially-distributed modulation of synaptic signalling thus contributing to the enrichment of information processing by the neuronal networks. Still, further research is needed to bridge the substantial gaps in our understanding of mechanisms and physiological relevance of astrocyte-neuron glutamatergic interactions, in particular ability of astrocytes directly activate neuronal glutamate receptors by releasing glutamate and, arguably, d-Serine. An emerging roles for aberrant changes in glutamatergic astroglial signalling, both neuroprotective and pathogenic, in neurological and neurodegenerative diseases also require further investigation. This article is part of the special Issue on 'Glutamate Receptors - The Glutamatergic Synapse'.
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Affiliation(s)
- Ulyana Lalo
- School of Life Sciences, Immanuel Kant Baltic Federal University, Kaliningrad, Russia
| | - Wuhyun Koh
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon, 34126, South Korea
| | - C Justin Lee
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon, 34126, South Korea
| | - Yuriy Pankratov
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, United Kingdom.
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5
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Copeland CS, Neale SA, Nisenbaum ES, Salt TE. Group II metabotropic glutamate receptor (mGlu 2 and mGlu 3 ) roles in thalamic processing. Br J Pharmacol 2021; 179:1607-1619. [PMID: 34355803 DOI: 10.1111/bph.15640] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 06/02/2021] [Accepted: 07/12/2021] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND AND PURPOSE As the thalamus underpins almost all aspects of behaviour, it is important to understand how the thalamus operates. Group II metabotropic glutamate (mGlu2 /mGlu3 ) receptor activation reduces inhibition in thalamic nuclei originating from the surrounding thalamic reticular nucleus (TRN). Whilst an mGlu2 component to this effect has been reported, in this study, we demonstrate that it is likely, largely mediated via mGlu3 . EXPERIMENTAL APPROACH The somatosensory ventrobasal thalamus (VB) is an established model for probing fundamental principles of thalamic function. In vitro slices conserving VB-TRN circuitry from wild-type and mGlu3 knockout mouse brains were used to record IPSPs and mIPSCs. In vivo extracellular recordings were made from VB neurons in anaesthetised rats. A range of selective pharmacological agents were used to probe Group II mGlu receptor function (agonist, LY354740; antagonist, LY341495; mGlu2 positive allosteric modulator, LY487379 and mixed mGlu2 agonist/mGlu3 antagonist LY395756). KEY RESULTS The in vitro and in vivo data are complementary and suggest that mGlu3 receptor activation is largely responsible for potentiating responses to somatosensory stimulation by reducing inhibition from the TRN. CONCLUSIONS AND IMPLICATIONS mGlu3 receptor activation in the VB likely enables important somatosensory information to be discerned from background activity. These mGlu3 receptors are likely to be endogenously activated via 'glutamate spillover'. In cognitive thalamic nuclei, this mechanism may be of importance in governing attentional processes. Positive allosteric modulation of endogenous mGlu3 receptor activation may therefore enhance cognitive function in pathophysiological disease states, such as schizophrenia, thus representing a highly specific therapeutic target.
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Affiliation(s)
- Caroline S Copeland
- Institute of Pharmaceutical Sciences, King's College London, London, UK.,Institute of Ophthalmology, University College London, London, UK
| | | | - Eric S Nisenbaum
- Pain/Migraine Research Group, Eli Lilly and Company, Indianapolis, Indiana, USA
| | - Thomas E Salt
- Institute of Ophthalmology, University College London, London, UK.,Neurexpert Limited, The Core, Newcastle upon Tyne, UK
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Olivero G, Vergassola M, Cisani F, Roggeri A, Pittaluga A. Presynaptic Release-regulating Metabotropic Glutamate Receptors: An Update. Curr Neuropharmacol 2021; 18:655-672. [PMID: 31775600 PMCID: PMC7457419 DOI: 10.2174/1570159x17666191127112339] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 11/15/2019] [Accepted: 11/22/2019] [Indexed: 12/18/2022] Open
Abstract
Metabotropic glutamate (mGlu) receptors represent the largest family of glutamate receptors in mammals and act as fine tuners of the chemical transmission in central nervous system (CNS). In the last decade, results concerning the expression and the subcellular localization of mGlu receptors further clarified their role in physio-pathological conditions. Concomitantly, their pharmacological characterization largely improved thanks to the identification of new compounds (chemical ligands and antibodies recognizing epitopic sequences of the receptor proteins) that allowed to decipher the protein compositions of the naive receptors. mGlu receptors are expressed at the presynaptic site of chemical synapses. Here, they modulate intraterminal enzymatic pathways controlling the migration and the fusion of vesicles to synaptic membranes as well as the phosphorylation of colocalized receptors. Both the control of transmitter exocytosis and the phosphorylation of colocalized receptors elicited by mGlu receptors are relevant events that dictate the plasticity of nerve terminals, and account for the main role of presynaptic mGlu receptors as modulators of neuronal signalling. The role of the presynaptic mGlu receptors in the CNS has been the matter of several studies and this review aims at briefly summarizing the recent observations obtained with isolated nerve endings (we refer to as synaptosomes). We focus on the pharmacological characterization of these receptors and on their receptor-receptor interaction / oligo-dimerization in nerve endings that could be relevant to the development of new therapeutic approaches for the cure of central pathologies.
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Affiliation(s)
| | | | | | | | - Anna Pittaluga
- Department of Pharmacy, University of Genoa, Genoa, Italy.,Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Ospedale Policlinico San Martino, Genoa, Italy
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Orgován Z, Ferenczy GG, Keserű GM. Allosteric Molecular Switches in Metabotropic Glutamate Receptors. ChemMedChem 2021; 16:81-93. [PMID: 32686363 PMCID: PMC7818470 DOI: 10.1002/cmdc.202000444] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Indexed: 12/22/2022]
Abstract
Metabotropic glutamate receptors (mGlu) are class C G protein-coupled receptors of eight subtypes that are omnipresently expressed in the central nervous system. mGlus have relevance in several psychiatric and neurological disorders, therefore they raise considerable interest as drug targets. Allosteric modulators of mGlus offer advantages over orthosteric ligands owing to their increased potential to achieve subtype selectivity, and this has prompted discovery programs that have produced a large number of reported allosteric mGlu ligands. However, the optimization of allosteric ligands into drug candidates has proved to be challenging owing to induced-fit effects, flat or steep structure-activity relationships and unexpected changes in theirpharmacology. Subtle structural changes identified as molecular switches might modulate the functional activity of allosteric ligands. Here we review these switches discovered in the metabotropic glutamate receptor family..
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Affiliation(s)
- Zoltán Orgován
- Medicinal Chemistry Research GroupResearch Centre for Natural SciencesMagyar tudósok krt. 2Budapest1117Hungary
| | - György G. Ferenczy
- Medicinal Chemistry Research GroupResearch Centre for Natural SciencesMagyar tudósok krt. 2Budapest1117Hungary
| | - György M. Keserű
- Medicinal Chemistry Research GroupResearch Centre for Natural SciencesMagyar tudósok krt. 2Budapest1117Hungary
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Gregory KJ, Goudet C. International Union of Basic and Clinical Pharmacology. CXI. Pharmacology, Signaling, and Physiology of Metabotropic Glutamate Receptors. Pharmacol Rev 2020; 73:521-569. [PMID: 33361406 DOI: 10.1124/pr.119.019133] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Metabotropic glutamate (mGlu) receptors respond to glutamate, the major excitatory neurotransmitter in the mammalian brain, mediating a modulatory role that is critical for higher-order brain functions such as learning and memory. Since the first mGlu receptor was cloned in 1992, eight subtypes have been identified along with many isoforms and splice variants. The mGlu receptors are transmembrane-spanning proteins belonging to the class C G protein-coupled receptor family and represent attractive targets for a multitude of central nervous system disorders. Concerted drug discovery efforts over the past three decades have yielded a wealth of pharmacological tools including subtype-selective agents that competitively block or mimic the actions of glutamate or act allosterically via distinct sites to enhance or inhibit receptor activity. Herein, we review the physiologic and pathophysiological roles for individual mGlu receptor subtypes including the pleiotropic nature of intracellular signal transduction arising from each. We provide a comprehensive analysis of the in vitro and in vivo pharmacological properties of prototypical and commercially available orthosteric agonists and antagonists as well as allosteric modulators, including ligands that have entered clinical trials. Finally, we highlight emerging areas of research that hold promise to facilitate rational design of highly selective mGlu receptor-targeting therapeutics in the future. SIGNIFICANCE STATEMENT: The metabotropic glutamate receptors are attractive therapeutic targets for a range of psychiatric and neurological disorders. Over the past three decades, intense discovery efforts have yielded diverse pharmacological tools acting either competitively or allosterically, which have enabled dissection of fundamental biological process modulated by metabotropic glutamate receptors and established proof of concept for many therapeutic indications. We review metabotropic glutamate receptor molecular pharmacology and highlight emerging areas that are offering new avenues to selectively modulate neurotransmission.
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Affiliation(s)
- Karen J Gregory
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (K.J.G.) and Institut de Génomique Fonctionnelle (IGF), University of Montpellier, Centre National de la Recherche Scientifique (CNRS), Institut National de la Sante et de la Recherche Medicale (INSERM), Montpellier, France (C.G.)
| | - Cyril Goudet
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (K.J.G.) and Institut de Génomique Fonctionnelle (IGF), University of Montpellier, Centre National de la Recherche Scientifique (CNRS), Institut National de la Sante et de la Recherche Medicale (INSERM), Montpellier, France (C.G.)
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Monn JA, Henry SS, Massey SM, Clawson DK, Chen Q, Diseroad BA, Bhardwaj RM, Atwell S, Lu F, Wang J, Russell M, Heinz BA, Wang XS, Carter JH, Getman BG, Adragni K, Broad LM, Sanger HE, Ursu D, Catlow JT, Swanson S, Johnson BG, Shaw DB, McKinzie DL, Hao J. Synthesis and Pharmacological Characterization of C4 β-Amide-Substituted 2-Aminobicyclo[3.1.0]hexane-2,6-dicarboxylates. Identification of (1 S,2 S,4 S,5 R,6 S)-2-Amino-4-[(3-methoxybenzoyl)amino]bicyclo[3.1.0]hexane-2,6-dicarboxylic Acid (LY2794193), a Highly Potent and Selective mGlu 3 Receptor Agonist. J Med Chem 2018; 61:2303-2328. [PMID: 29350927 DOI: 10.1021/acs.jmedchem.7b01481] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Multiple therapeutic opportunities have been suggested for compounds capable of selective activation of metabotropic glutamate 3 (mGlu3) receptors, but small molecule tools are lacking. As part of our ongoing efforts to identify potent, selective, and systemically bioavailable agonists for mGlu2 and mGlu3 receptor subtypes, a series of C4β-N-linked variants of (1 S,2 S,5 R,6 S)-2-amino-bicyclo[3.1.0]hexane-2,6-dicarboxylic acid 1 (LY354740) were prepared and evaluated for both mGlu2 and mGlu3 receptor binding affinity and functional cellular responses. From this investigation we identified (1 S,2 S,4 S,5 R,6 S)-2-amino-4-[(3-methoxybenzoyl)amino]bicyclo[3.1.0]hexane-2,6-dicarboxylic acid 8p (LY2794193), a molecule that demonstrates remarkable mGlu3 receptor selectivity. Crystallization of 8p with the amino terminal domain of hmGlu3 revealed critical binding interactions for this ligand with residues adjacent to the glutamate binding site, while pharmacokinetic assessment of 8p combined with its effect in an mGlu2 receptor-dependent behavioral model provides estimates for doses of this compound that would be expected to selectively engage and activate central mGlu3 receptors in vivo.
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10
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Olivero G, Bonfiglio T, Vergassola M, Usai C, Riozzi B, Battaglia G, Nicoletti F, Pittaluga A. Immuno-pharmacological characterization of group II metabotropic glutamate receptors controlling glutamate exocytosis in mouse cortex and spinal cord. Br J Pharmacol 2017; 174:4785-4796. [PMID: 28967122 PMCID: PMC5727332 DOI: 10.1111/bph.14061] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 09/12/2017] [Accepted: 09/13/2017] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND AND PURPOSE We recently proposed the existence of mGlu3 -preferring autoreceptors in spinal cord terminals and of mGlu2 -preferring autoreceptors in cortical terminals. This study aims to verify our previous conclusions and to extend their pharmacological characterization. EXPERIMENTAL APPROACH We studied the effect of LY566332, an mGlu2 receptor positive allosteric modulator (PAM), and of LY2389575, a selective mGlu3 receptor negative allosteric (NAM) modulator, on the mGlu2/3 agonist LY379268-mediated inhibition of glutamate exocytosis [measured as KCl-evoked release of preloaded [3 H]-D-aspartate]. The mGlu2 PAM BINA and the mGlu3 NAM ML337, as well as selective antibodies recognizing the N-terminal of the receptor proteins, were used to confirm the pharmacological characterization of the native receptors. KEY RESULTS Cortical synaptosomes possess LY566332-sensitive autoreceptors that are slightly, although significantly, susceptible to LY2389575. In contrast, LY566332-insensitive and LY2389575-sensitive autoreceptors are present in spinal cord terminals. BINA and ML337 mimicked LY566332 and LY2389575, respectively, in controlling LY379268-mediated inhibition of glutamate exocytosis from both cortical and spinal cord synaptosomes. Incubation of cortical synaptosomes with anti-mGlu2 antibody prevented the LY379268-induced inhibition of glutamate exocytosis, and this response was partially reduced by the anti-mGlu3 antibody. Incubation of spinal cord synaptosomes with the anti-mGlu3 antibody abolished LY379268-mediated reduction of glutamate exocytosis from these terminals, while the anti-mGlu2 antibody was inactive. Western blot analysis and confocal microscopy data were largely consistent with these functional observations. CONCLUSIONS AND IMPLICATIONS We confirmed that mGlu3 -preferring autoreceptors exist in spinal cord terminals. Differently, cortical glutamatergic terminals possess mGlu2 /mGlu3 heterodimers, whose inhibitory effect is largely mediated by mGlu2 receptors.
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Affiliation(s)
| | | | | | - Cesare Usai
- National Research CouncilInstitute of BiophysicsGenoaItaly
| | | | | | - Ferdinando Nicoletti
- I.R.C.C.S. Neuromed, Località CamerellePozzilliItaly
- Department of Physiology and PharmacologySapienza UniversityRomeItaly
| | - Anna Pittaluga
- Department of Pharmacy, DiFARUniversity of GenoaGenoaItaly
- Centre of Excellence for Biomedical ResearchUniversity of GenoaGenoaItaly
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11
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Johnson KA, Mateo Y, Lovinger DM. Metabotropic glutamate receptor 2 inhibits thalamically-driven glutamate and dopamine release in the dorsal striatum. Neuropharmacology 2017; 117:114-123. [PMID: 28159646 DOI: 10.1016/j.neuropharm.2017.01.038] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 01/20/2017] [Accepted: 01/30/2017] [Indexed: 11/26/2022]
Abstract
The striatum plays critical roles in action control and cognition, and activity of striatal neurons is driven by glutamatergic input. Inhibition of glutamatergic inputs to projection neurons and interneurons of the striatum by presynaptic G protein-coupled receptors (GPCRs) stands to modulate striatal output and striatum-dependent behaviors. Despite knowledge that a substantial number of glutamatergic inputs to striatal neurons originate in the thalamus, most electrophysiological studies assessing GPCR modulation do not differentiate between effects on corticostriatal and thalamostriatal transmission, and synaptic inhibition is frequently assumed to be mediated by activation of GPCRs on corticostriatal terminals. We used optogenetic techniques and recently-discovered pharmacological tools to dissect the effects of a prominent presynaptic GPCR, metabotropic glutamate receptor 2 (mGlu2), on corticostriatal vs. thalamostriatal transmission. We found that an agonist of mGlu2 and mGlu3 induces long-term depression (LTD) at synapses onto MSNs from both the cortex and the thalamus. Thalamostriatal LTD is selectively blocked by an mGlu2-selective negative allosteric modulator and reversed by application of an antagonist following LTD induction. Activation of mGlu2/3 also induces LTD of thalamostriatal transmission in striatal cholinergic interneurons (CINs), and pharmacological activation of mGlu2/3 or selective activation of mGlu2 inhibits CIN-mediated dopamine release evoked by selective stimulation of thalamostriatal inputs. Thus, mGlu2 activation exerts effects on striatal physiology that extend beyond modulation of corticostriatal synapses, and has the potential to influence cognition and striatum-related disorders via inhibition of thalamus-derived glutamate and dopamine release.
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Affiliation(s)
- Kari A Johnson
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, 5625 Fishers Lane TS-13, Rockville, MD 20852, USA
| | - Yolanda Mateo
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, 5625 Fishers Lane TS-13, Rockville, MD 20852, USA
| | - David M Lovinger
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, 5625 Fishers Lane TS-13, Rockville, MD 20852, USA.
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12
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Johnson KA, Lovinger DM. Presynaptic G Protein-Coupled Receptors: Gatekeepers of Addiction? Front Cell Neurosci 2016; 10:264. [PMID: 27891077 PMCID: PMC5104741 DOI: 10.3389/fncel.2016.00264] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 10/31/2016] [Indexed: 12/21/2022] Open
Abstract
Drug abuse and addiction cause widespread social and public health problems, and the neurobiology underlying drug actions and drug use and abuse is an area of intensive research. Drugs of abuse alter synaptic transmission, and these actions contribute to acute intoxication as well as the chronic effects of abused substances. Transmission at most mammalian synapses involves neurotransmitter activation of two receptor subtypes, ligand-gated ion channels that mediate fast synaptic responses and G protein-coupled receptors (GPCRs) that have slower neuromodulatory actions. The GPCRs represent a large proportion of neurotransmitter receptors involved in almost all facets of nervous system function. In addition, these receptors are targets for many pharmacotherapeutic agents. Drugs of abuse directly or indirectly affect neuromodulation mediated by GPCRs, with important consequences for intoxication, drug taking and responses to prolonged drug exposure, withdrawal and addiction. Among the GPCRs are several subtypes involved in presynaptic inhibition, most of which are coupled to the Gi/o class of G protein. There is increasing evidence that these presynaptic Gi/o-coupled GPCRs have important roles in the actions of drugs of abuse, as well as behaviors related to these drugs. This topic will be reviewed, with particular emphasis on receptors for three neurotransmitters, Dopamine (DA; D1- and D2-like receptors), Endocannabinoids (eCBs; CB1 receptors) and glutamate (group II metabotropic glutamate (mGlu) receptors). The focus is on recent evidence from laboratory animal models (and some evidence in humans) implicating these receptors in the acute and chronic effects of numerous abused drugs, as well as in the control of drug seeking and taking. The ability of drugs targeting these receptors to modify drug seeking behavior has raised the possibility of using compounds targeting these receptors for addiction pharmacotherapy. This topic is also discussed, with emphasis on development of mGlu2 positive allosteric modulators (PAMs).
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Affiliation(s)
- Kari A. Johnson
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of HealthBethesda, MD, USA
| | - David M. Lovinger
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of HealthBethesda, MD, USA
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13
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Wood CM, Nicolas CS, Choi SL, Roman E, Nylander I, Fernandez-Teruel A, Kiianmaa K, Bienkowski P, de Jong TR, Colombo G, Chastagnier D, Wafford KA, Collingridge GL, Wildt SJ, Conway-Campbell BL, Robinson ESJ, Lodge D. Prevalence and influence of cys407* Grm2 mutation in Hannover-derived Wistar rats: mGlu2 receptor loss links to alcohol intake, risk taking and emotional behaviour. Neuropharmacology 2016; 115:128-138. [PMID: 26987983 DOI: 10.1016/j.neuropharm.2016.03.020] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Revised: 03/09/2016] [Accepted: 03/10/2016] [Indexed: 12/30/2022]
Abstract
Modulation of metabotropic glutamate 2 (mGlu2) receptor function has huge potential for treating psychiatric and neurological diseases. Development of drugs acting on mGlu2 receptors depends on the development and use of translatable animal models of disease. We report here a stop codon mutation at cysteine 407 in Grm2 (cys407*) that is common in some Wistar rats. Therefore, researchers in this field need to be aware of strains with this mutation. Our genotypic survey found widespread prevalence of the mutation in commercial Wistar strains, particularly those known as Han Wistar. Such Han Wistar rats are ideal for research into the separate roles of mGlu2 and mGlu3 receptors in CNS function. Previous investigations, unknowingly using such mGlu2 receptor-lacking rats, provide insights into the role of mGlu2 receptors in behaviour. The Grm2 mutant rats, which dominate some selectively bred lines, display characteristics of altered emotionality, impulsivity and risk-related behaviours and increased voluntary alcohol intake compared with their mGlu2 receptor-competent counterparts. In addition, the data further emphasize the potential therapeutic role of mGlu2 receptors in psychiatric and neurological disease, and indicate novel methods of studying the role of mGlu2 and mGlu3 receptors. This article is part of the Special Issue entitled 'Metabotropic Glutamate Receptors, 5 years on'.
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Affiliation(s)
- Christian M Wood
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol BS8 1TD, UK
| | - Celine S Nicolas
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol BS8 1TD, UK
| | - Sun-Lim Choi
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol BS8 1TD, UK
| | - Erika Roman
- Neuropharmacology, Addiction and Behaviour, Department of Pharmaceutical Biosciences, Uppsala University, P.O. Box 591, 751 24 Uppsala, Sweden
| | - Ingrid Nylander
- Neuropharmacology, Addiction and Behaviour, Department of Pharmaceutical Biosciences, Uppsala University, P.O. Box 591, 751 24 Uppsala, Sweden
| | - Alberto Fernandez-Teruel
- Department of Psychiatry and Forensic Medicine, Institute of Neurosciences, Autonomous University of Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Kalervo Kiianmaa
- Department of Alcohol, Drugs and Addiction, National Institute for Health and Welfare, POB 30 00271 Helsinki, Finland
| | | | - Trynke R de Jong
- Department of Behavioural and Molecular Neuroendocrinology, University of Regensburg, 93040 Regensburg, Germany
| | - Giancarlo Colombo
- Neuroscience Institute, Section of Cagliari, National Research Council of Italy, I09042 Monserrato, CA, Italy
| | - Denis Chastagnier
- Janvier Labs, CS4105 Le Genest-Saint-Isle, F-53941 Saint-Berthevin, France
| | - Keith A Wafford
- Eli Lilly Research Laboratories, Windlesham, Surrey GU20 6PH, UK
| | - Graham L Collingridge
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol BS8 1TD, UK
| | - Sheryl J Wildt
- Envigo, 8520 Allison Pointe Boulevard, Indianapolis IN 46250, USA
| | - Becky L Conway-Campbell
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY, UK
| | - Emma S J Robinson
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol BS8 1TD, UK
| | - David Lodge
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol BS8 1TD, UK.
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14
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Di Prisco S, Merega E, Bonfiglio T, Olivero G, Cervetto C, Grilli M, Usai C, Marchi M, Pittaluga A. Presynaptic, release-regulating mGlu2 -preferring and mGlu3 -preferring autoreceptors in CNS: pharmacological profiles and functional roles in demyelinating disease. Br J Pharmacol 2016; 173:1465-77. [PMID: 26791341 DOI: 10.1111/bph.13442] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Revised: 01/08/2016] [Accepted: 01/17/2016] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND AND PURPOSE Presynaptic, release-regulating metabotropic glutamate 2 and 3 (mGlu2/3) autoreceptors exist in the CNS. They represent suitable targets for therapeutic approaches to central diseases that are typified by hyperglutamatergicity. The availability of specific ligands able to differentiate between mGlu2 and mGlu3 subunits allows us to further characterize these autoreceptors. In this study we investigated the pharmacological profile of mGlu2/3 receptors in selected CNS regions and evaluated their functions in mice with experimental autoimmune encephalomyelitis (EAE). EXPERIMENTAL APPROACH The comparative analysis of presynaptic mGlu2/3 autoreceptors was performed by determining the effect of selective mGlu2/3 receptor agonist(s) and antagonist(s) on the release of [(3)H]-D-aspartate from cortical and spinal cord synaptosomes in superfusion. In EAE mice, mGlu2/3 autoreceptor-mediated release functions were investigated and effects of in vivo LY379268 administration on impaired glutamate release examined ex vivo. KEY RESULTS Western blot analysis and confocal microscopy confirmed the presence of presynaptic mGlu2/3 receptor proteins. Cortical synaptosomes possessed LY541850-sensitive, NAAG-insensitive autoreceptors having low affinity for LY379268, while LY541850-insensitive, NAAG-sensitive autoreceptors with high affinity for LY379268 existed in spinal cord terminals. In EAE mice, mGlu2/3 autoreceptors completely lost their inhibitory activity in cortical, but not in spinal cord synaptosomes. In vivo LY379268 administration restored the glutamate exocytosis capability in spinal cord but not in cortical terminals in EAE mice. CONCLUSIONS AND IMPLICATIONS We propose the existence of mGlu2-preferring and mGlu3-preferring autoreceptors in mouse cortex and spinal cord respectively. The mGlu3 -preferring autoreceptors could represent a target for new pharmacological approaches for treating demyelinating diseases.
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Affiliation(s)
- Silvia Di Prisco
- Department of Pharmacy, DiFAR, Pharmacology and Toxicology Section, University of Genoa, Genoa, Italy
| | - Elisa Merega
- Department of Pharmacy, DiFAR, Pharmacology and Toxicology Section, University of Genoa, Genoa, Italy
| | - Tommaso Bonfiglio
- Department of Pharmacy, DiFAR, Pharmacology and Toxicology Section, University of Genoa, Genoa, Italy
| | - Guendalina Olivero
- Department of Pharmacy, DiFAR, Pharmacology and Toxicology Section, University of Genoa, Genoa, Italy
| | - Chiara Cervetto
- Department of Pharmacy, DiFAR, Pharmacology and Toxicology Section, University of Genoa, Genoa, Italy
| | - Massimo Grilli
- Department of Pharmacy, DiFAR, Pharmacology and Toxicology Section, University of Genoa, Genoa, Italy
| | - Cesare Usai
- Institute of Biophysics, National Research Council, Genoa, Italy
| | - Mario Marchi
- Department of Pharmacy, DiFAR, Pharmacology and Toxicology Section, University of Genoa, Genoa, Italy.,Center of Excellence for Biomedical Research, University of Genoa, Genoa, Italy
| | - Anna Pittaluga
- Department of Pharmacy, DiFAR, Pharmacology and Toxicology Section, University of Genoa, Genoa, Italy.,Center of Excellence for Biomedical Research, University of Genoa, Genoa, Italy
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15
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Huynh THV, Erichsen MN, Tora AS, Goudet C, Sagot E, Assaf Z, Thomsen C, Brodbeck R, Stensbøl TB, Bjørn-Yoshimoto WE, Nielsen B, Pin JP, Gefflaut T, Bunch L. New 4-Functionalized Glutamate Analogues Are Selective Agonists at Metabotropic Glutamate Receptor Subtype 2 or Selective Agonists at Metabotropic Glutamate Receptor Group III. J Med Chem 2016; 59:914-24. [PMID: 26814576 DOI: 10.1021/acs.jmedchem.5b01333] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The metabotropic glutamate (Glu) receptors (mGluRs) play key roles in modulating excitatory neurotransmission in the brain. In all, eight subtypes have been identified and divided into three groups, group I (mGlu1,5), group II (mGlu2,3), and group III (mGlu4,6-8). In this article, we present a L-2,4-syn-substituted Glu analogue, 1d, which displays selective agonist activity at mGlu2 over the remaining mGluR subtypes. A modeling study and redesign of the core scaffold led to the stereoselective synthesis of four new conformationally restricted Glu analogues, 2a-d. Most interestingly, 2a retained a selective agonist activity profile at mGlu2 (EC50 in the micromolar range), whereas 2c/2d were both selective agonists at group III, subtypes mGlu4,6,8. In general, 2d was 20-fold more potent than 2c and potently activated mGlu4,6,8 in the low-mid nanomolar range.
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Affiliation(s)
- Tri H V Huynh
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , 2100 Copenhagen, Denmark
| | - Mette N Erichsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , 2100 Copenhagen, Denmark
| | - Amélie S Tora
- Institute of Functional Genomics, CNRS, UMR5203, University of Montpellier , 34094 Montpellier, France.,INSERM, U1191 , 34094 Montpellier, France
| | - Cyril Goudet
- Institute of Functional Genomics, CNRS, UMR5203, University of Montpellier , 34094 Montpellier, France.,INSERM, U1191 , 34094 Montpellier, France
| | - Emmanuelle Sagot
- Institut de Chimie de Clermont-Ferrand, Clermont Université, Université Blaise Pascal, BP 10448 , 63000 Clermont-Ferrand, France.,CNRS, UMR6296, ICCF, BP 80026 , 63177 Aubière, France
| | - Zeinab Assaf
- Institut de Chimie de Clermont-Ferrand, Clermont Université, Université Blaise Pascal, BP 10448 , 63000 Clermont-Ferrand, France.,CNRS, UMR6296, ICCF, BP 80026 , 63177 Aubière, France
| | | | | | | | - Walden E Bjørn-Yoshimoto
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , 2100 Copenhagen, Denmark
| | - Birgitte Nielsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , 2100 Copenhagen, Denmark
| | - Jean-Philippe Pin
- Institute of Functional Genomics, CNRS, UMR5203, University of Montpellier , 34094 Montpellier, France.,INSERM, U1191 , 34094 Montpellier, France
| | - Thierry Gefflaut
- Institut de Chimie de Clermont-Ferrand, Clermont Université, Université Blaise Pascal, BP 10448 , 63000 Clermont-Ferrand, France.,CNRS, UMR6296, ICCF, BP 80026 , 63177 Aubière, France
| | - Lennart Bunch
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , 2100 Copenhagen, Denmark
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16
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LY395756, an mGluR2 agonist and mGluR3 antagonist, enhances NMDA receptor expression and function in the normal adult rat prefrontal cortex, but fails to improve working memory and reverse MK801-induced working memory impairment. Exp Neurol 2015; 273:190-201. [PMID: 26341392 DOI: 10.1016/j.expneurol.2015.08.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 08/06/2015] [Accepted: 08/25/2015] [Indexed: 11/22/2022]
Abstract
Targeting group II metabotropic glutamate receptors (mGluR2/3) has been proposed to correct the dysfunctional glutamatergic system, particularly NMDA receptor (NMDAR) hypofunction, for treatment of schizophrenia. However, how activation of mGluR2/3 affects NMDAR function in adult animals remains elusive. Here we show the effects of LY395756 (LY39), a compound acting as both an mGluR2 agonist and mGluR3 antagonist, on the NMDAR expression and function of normal adult rat prefrontal cortex (PFC) as well as working memory function in the MK801 model of schizophrenia. We found that in vivo administration of LY39 significantly increased the total protein levels of NMDAR subunits and NR2B phosphorylationin the PFC, along with the amplitude of NMDAR-mediated miniature excitatory postsynaptic currents (mEPSC) in the prefrontal cortical neurons. Moreover, LY39 also significantly increased mTOR and pmTOR expression, but not ERK1/2, Akt, and GSK3β, suggesting an activation of mTOR signaling. Indeed, the mTOR inhibitor rapamycin, and actinomycin-D, a transcription inhibitor, blocked the enhanced effects of LY39 on NMDAR-mEPSCs. These results indicate that LY39 regulates NMDAR expression and function through unidentified mTOR-mediated protein synthesis in the normal adult rat PFC. However, this change is insufficient to affect working memory function in normal animals, nor to reverse the MK801-induced working memory deficit. Our data provide the first evidence of an in vivo effect of a novel compound that acts as both an mGluR2 agonist and mGluR3 antagonist on synaptic NMDAR expression and function in the adult rat PFC, although its effect -on PFC-dependent cognitive function remains to be explored.
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17
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Li ML, Hu XQ, Li F, Gao WJ. Perspectives on the mGluR2/3 agonists as a therapeutic target for schizophrenia: Still promising or a dead end? Prog Neuropsychopharmacol Biol Psychiatry 2015; 60:66-76. [PMID: 25724760 PMCID: PMC4426221 DOI: 10.1016/j.pnpbp.2015.02.012] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Revised: 02/16/2015] [Accepted: 02/17/2015] [Indexed: 01/08/2023]
Abstract
Group II metabotropic glutamate receptor (mGluR2/3) agonists once showed promise as non-dopaminergic antipsychotic drugs because of their efficacy in alleviating symptoms of schizophrenia (SZ) in both animal models and human patients. However, the recent failure of Phase III clinical trials dealt a huge blow to the scientific community and the aftershock of the setback in mGluR2/3 research can be felt everywhere from grant support and laboratory studies to paper publication. An immediate question raised is whether mGluR2/3 is still a promising therapeutic target for schizophrenia. Answering this question is not easy, but apparently a new strategy is needed. This article provides a focused review of literature on the study of mGluR2/3 agonists, especially on mGluR2/3 agonists' mechanism of action and efficacy in both normal conditions and animal models of SZ, as well as clinical studies in human patients with the disease. We argue that the cellular and molecular actions of mGluR2/3 agonists, the distinct roles between mGluR2 and mGluR3, as well as their effects on different stages of the disease and different subpopulations of patients, remain incompletely studied. Until the mechanisms associated with mGluR2/3 are clearly elucidated and all treatment options are tested, it would be a great mistake to terminate the study of mGluR2/3 as a therapeutic target for schizophrenia. This review will thus shed light on the comprehensive features of the translational potential mGluR2/3 agonists as well as the need for further research into the more selective activation of mGluR2.
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Affiliation(s)
- Meng-Lin Li
- Drexel University College of Medicine, Philadelphia, PA, USA,Department of Rehabilitation, Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China
| | - Xi-Quan Hu
- Department of Rehabilitation, Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China
| | - Feng Li
- Department of Neurobiology and Anatomy, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Wen-Jun Gao
- Drexel University College of Medicine, Philadelphia, PA, USA.
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18
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Monn JA, Prieto L, Taboada L, Pedregal C, Hao J, Reinhard MR, Henry SS, Goldsmith PJ, Beadle CD, Walton L, Man T, Rudyk H, Clark B, Tupper D, Baker SR, Lamas C, Montero C, Marcos A, Blanco J, Bures M, Clawson DK, Atwell S, Lu F, Wang J, Russell M, Heinz BA, Wang X, Carter JH, Xiang C, Catlow JT, Swanson S, Sanger H, Broad LM, Johnson MP, Knopp KL, Simmons RMA, Johnson BG, Shaw DB, McKinzie DL. Synthesis and Pharmacological Characterization of C4-Disubstituted Analogs of 1S,2S,5R,6S-2-Aminobicyclo[3.1.0]hexane-2,6-dicarboxylate: Identification of a Potent, Selective Metabotropic Glutamate Receptor Agonist and Determination of Agonist-Bound Human mGlu2 and mGlu3 Amino Terminal Domain Structures. J Med Chem 2015; 58:1776-94. [DOI: 10.1021/jm501612y] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- James A. Monn
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Lourdes Prieto
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Lorena Taboada
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Concepcion Pedregal
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Junliang Hao
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Matt R. Reinhard
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Steven S. Henry
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Paul J. Goldsmith
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Christopher D. Beadle
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Lesley Walton
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Teresa Man
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Helene Rudyk
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Barry Clark
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - David Tupper
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - S. Richard Baker
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Carlos Lamas
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Carlos Montero
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Alicia Marcos
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Jaime Blanco
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Mark Bures
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - David K. Clawson
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Shane Atwell
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Frances Lu
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Jing Wang
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Marijane Russell
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Beverly A. Heinz
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Xushan Wang
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Joan H. Carter
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Chuanxi Xiang
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - John T. Catlow
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Steven Swanson
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Helen Sanger
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Lisa M. Broad
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Michael P. Johnson
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Kelly L. Knopp
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Rosa M. A. Simmons
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - Bryan G. Johnson
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - David B. Shaw
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
| | - David L. McKinzie
- Discovery Chemistry
Research and Technologies, ‡Quantitative Biology, §Structural Biology, ∥Drug Disposition,
and ⊥Neuroscience
Research, Eli Lilly and Company, Indianapolis, Indiana 46285, United States
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19
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Dhanya RP, Sheffler DJ, Dahl R, Davis M, Lee PS, Yang L, Nickols HH, Cho HP, Smith LH, D'Souza MS, Conn PJ, Der-Avakian A, Markou A, Cosford NDP. Design and synthesis of systemically active metabotropic glutamate subtype-2 and -3 (mGlu2/3) receptor positive allosteric modulators (PAMs): pharmacological characterization and assessment in a rat model of cocaine dependence. J Med Chem 2014; 57:4154-72. [PMID: 24735492 PMCID: PMC4033659 DOI: 10.1021/jm5000563] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
![]()
As
part of our ongoing small-molecule metabotropic glutamate (mGlu) receptor
positive allosteric modulator (PAM) research, we performed structure–activity
relationship (SAR) studies around a series of group II mGlu PAMs.
Initial analogues exhibited weak activity as mGlu2 receptor
PAMs and no activity at mGlu3. Compound optimization led
to the identification of potent mGlu2/3 selective PAMs
with no in vitro activity at mGlu1,4–8 or 45 other
CNS receptors. In vitro pharmacological characterization of representative
compound 44 indicated agonist-PAM activity toward mGlu2 and PAM activity at mGlu3. The most potent mGlu2/3 PAMs were characterized in assays predictive of ADME/T
and pharmacokinetic (PK) properties, allowing the discovery of systemically
active mGlu2/3 PAMs. On the basis of its overall profile,
compound 74 was selected for behavioral studies and was
shown to dose-dependently decrease cocaine self-administration in
rats after intraperitoneal administration. These mGlu2/3 receptor PAMs have significant potential as small molecule tools
for investigating group II mGlu pharmacology.
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Affiliation(s)
- Raveendra-Panickar Dhanya
- Cell Death and Survival Networks Program and Conrad Prebys Center for Chemical Genomics, Sanford-Burnham Medical Research Institute , 10901 N. Torrey Pines Road, La Jolla, California 92037, United States
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20
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Wenthur CJ, Morrison RD, Daniels JS, Conn PJ, Lindsley CW. Synthesis and SAR of substituted pyrazolo[1,5-a]quinazolines as dual mGlu(2)/mGlu(3) NAMs. Bioorg Med Chem Lett 2014; 24:2693-8. [PMID: 24794112 DOI: 10.1016/j.bmcl.2014.04.051] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 04/10/2014] [Accepted: 04/11/2014] [Indexed: 10/25/2022]
Abstract
Herein we report the design and synthesis of a series of substituted pyrazolo[1,5-a]quinazolin-5(4H)-ones as negative allosteric modulators of metabotropic glutamate receptors 2 and 3 (mGlu2 and mGlu3, respectively). Development of this series was initiated by reports that pyrazolo[1,5-a]quinazoline-derived scaffolds can yield compounds with activity at group II mGlu receptors which are prone to molecular switching following small structural changes. Several potent analogues, including 4-methyl-2-phenyl-8-(pyrimidin-5-yl)pyrazolo[1,5-a]quinazolin-5(4H)-one (10b), were discovered with potent in vitro activity as dual mGlu2/mGlu3 NAMs, with excellent selectivity versus the other mGluRs.
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Affiliation(s)
- Cody J Wenthur
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Ryan D Morrison
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - J Scott Daniels
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - P Jeffrey Conn
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Craig W Lindsley
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA.
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21
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Monn JA, Valli MJ, Massey SM, Hao J, Reinhard MR, Bures MG, Heinz BA, Wang X, Carter JH, Getman BG, Stephenson GA, Herin M, Catlow JT, Swanson S, Johnson BG, McKinzie DL, Henry SS. Synthesis and Pharmacological Characterization of 4-Substituted-2-Aminobicyclo[3.1.0]hexane-2,6-dicarboxylates: Identification of New Potent and Selective Metabotropic Glutamate 2/3 Receptor Agonists. J Med Chem 2013; 56:4442-55. [DOI: 10.1021/jm4000165] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- James A. Monn
- Discovery
Chemistry Research and Technologies, §Preformulation, ∥Drug Disposition and ⊥Neuroscience Research, Eli Lilly and Company, Indianapolis,
Indiana 46285, United States
| | - Matthew J. Valli
- Discovery
Chemistry Research and Technologies, §Preformulation, ∥Drug Disposition and ⊥Neuroscience Research, Eli Lilly and Company, Indianapolis,
Indiana 46285, United States
| | - Steven M. Massey
- Discovery
Chemistry Research and Technologies, §Preformulation, ∥Drug Disposition and ⊥Neuroscience Research, Eli Lilly and Company, Indianapolis,
Indiana 46285, United States
| | - Junliang Hao
- Discovery
Chemistry Research and Technologies, §Preformulation, ∥Drug Disposition and ⊥Neuroscience Research, Eli Lilly and Company, Indianapolis,
Indiana 46285, United States
| | - Matthew R. Reinhard
- Discovery
Chemistry Research and Technologies, §Preformulation, ∥Drug Disposition and ⊥Neuroscience Research, Eli Lilly and Company, Indianapolis,
Indiana 46285, United States
| | - Mark G. Bures
- Discovery
Chemistry Research and Technologies, §Preformulation, ∥Drug Disposition and ⊥Neuroscience Research, Eli Lilly and Company, Indianapolis,
Indiana 46285, United States
| | - Beverly A. Heinz
- Discovery
Chemistry Research and Technologies, §Preformulation, ∥Drug Disposition and ⊥Neuroscience Research, Eli Lilly and Company, Indianapolis,
Indiana 46285, United States
| | - Xushan Wang
- Discovery
Chemistry Research and Technologies, §Preformulation, ∥Drug Disposition and ⊥Neuroscience Research, Eli Lilly and Company, Indianapolis,
Indiana 46285, United States
| | - Joan H. Carter
- Discovery
Chemistry Research and Technologies, §Preformulation, ∥Drug Disposition and ⊥Neuroscience Research, Eli Lilly and Company, Indianapolis,
Indiana 46285, United States
| | - Brian G. Getman
- Discovery
Chemistry Research and Technologies, §Preformulation, ∥Drug Disposition and ⊥Neuroscience Research, Eli Lilly and Company, Indianapolis,
Indiana 46285, United States
| | - Gregory A. Stephenson
- Discovery
Chemistry Research and Technologies, §Preformulation, ∥Drug Disposition and ⊥Neuroscience Research, Eli Lilly and Company, Indianapolis,
Indiana 46285, United States
| | - Marc Herin
- Discovery
Chemistry Research and Technologies, §Preformulation, ∥Drug Disposition and ⊥Neuroscience Research, Eli Lilly and Company, Indianapolis,
Indiana 46285, United States
| | - John T. Catlow
- Discovery
Chemistry Research and Technologies, §Preformulation, ∥Drug Disposition and ⊥Neuroscience Research, Eli Lilly and Company, Indianapolis,
Indiana 46285, United States
| | - Steven Swanson
- Discovery
Chemistry Research and Technologies, §Preformulation, ∥Drug Disposition and ⊥Neuroscience Research, Eli Lilly and Company, Indianapolis,
Indiana 46285, United States
| | - Bryan G. Johnson
- Discovery
Chemistry Research and Technologies, §Preformulation, ∥Drug Disposition and ⊥Neuroscience Research, Eli Lilly and Company, Indianapolis,
Indiana 46285, United States
| | - David L. McKinzie
- Discovery
Chemistry Research and Technologies, §Preformulation, ∥Drug Disposition and ⊥Neuroscience Research, Eli Lilly and Company, Indianapolis,
Indiana 46285, United States
| | - Steven S. Henry
- Discovery
Chemistry Research and Technologies, §Preformulation, ∥Drug Disposition and ⊥Neuroscience Research, Eli Lilly and Company, Indianapolis,
Indiana 46285, United States
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22
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Optical control of metabotropic glutamate receptors. Nat Neurosci 2013; 16:507-16. [PMID: 23455609 PMCID: PMC3681425 DOI: 10.1038/nn.3346] [Citation(s) in RCA: 158] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 01/25/2013] [Indexed: 12/13/2022]
Abstract
G-protein coupled receptors (GPCRs), the largest family of membrane signaling proteins, respond to neurotransmitters, hormones and small environmental molecules. The neuronal function of many GPCRs has been difficult to resolve because of an inability to gate them with subtype-specificity, spatial precision, speed and reversibility. To address this, we developed an approach for opto-chemical engineering native GPCRs. We applied this to the metabotropic glutamate receptors (mGluRs) to generate light-agonized and light-antagonized “LimGluRs”. The light-agonized “LimGluR2”, on which we focused, is fast, bistable, and supports multiple rounds of on/off switching. Light gates two of the primary neuronal functions of mGluR2: suppression of excitability and inhibition of neurotransmitter release. The light-antagonized “LimGluR2block” can be used to manipulate negative feedback of synaptically released glutamate on transmitter release. We generalize the optical control to two additional family members: mGluR3 and 6. The system works in rodent brain slice and in zebrafish in vivo, where we find that mGluR2 modulates the threshold for escape behavior. These light-gated mGluRs pave the way for determining the roles of mGluRs in synaptic plasticity, memory and disease.
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23
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Mercier MS, Lodge D, Fang G, Nicolas CS, Collett VJ, Jane DE, Collingridge GL, Bortolotto ZA. Characterisation of an mGlu8 receptor-selective agonist and antagonist in the lateral and medial perforant path inputs to the dentate gyrus. Neuropharmacology 2012; 67:294-303. [PMID: 23220400 DOI: 10.1016/j.neuropharm.2012.11.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 11/22/2012] [Accepted: 11/23/2012] [Indexed: 02/06/2023]
Abstract
Since its characterisation in 2001, the mGlu8-selective agonist DCPG has been widely used to explore the potential functional role of this group III mGlu receptor within the central nervous system. This research has implicated mGlu8 receptors in a number of disease states and conditions such as epilepsy and anxiety, suggesting that mGlu8-selective ligands may hold important therapeutic potential. However, there is evidence that DCPG exerts off-target effects at higher concentrations, limiting its use as an mGlu8-selective agonist. Here, we have used field recordings in rat hippocampal slices to investigate the effects of DCPG in the lateral perforant path (LPP), a pathway known to express high levels of mGlu8. We show that DCPG does inhibit excitatory transmission in this pathway, but produces a biphasic concentration-response curve suggesting activation of two distinct receptor types. The putative mGlu8-selective antagonist MDCPG antagonises the high, but not the low, potency component of this concentration-response curve. In addition, higher concentrations of DCPG also depress excitatory transmission in the medial perforant path (MPP), a pathway expressing very low levels of mGlu8 receptors. Experiments in slices from mice lacking mGlu8 receptors indicate that concentrations of DCPG >1 μM produce large non-selective effects in both the LPP and MPP. Further experiments in slices from mGlu2, 4 and 7 knock-out mice, as well as in an mGlu2-deficient substrain of Wistar rat, reveal that these non-selective effects are mediated primarily by mGlu2 receptors. Taken together, our results confirm the mGlu8-selectivity of DCPG at submicromolar concentrations, but suggest that care must be taken when employing higher concentrations of the agonist, which may additionally activate mGlu2 receptors, especially at synapses where their expression is high. MDCPG may be a useful tool in determining whether observable DCPG effects are attributable to mGlu8, versus mGlu2, receptor activation.
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Affiliation(s)
- Marion S Mercier
- MRC Centre for Synaptic Plasticity, School of Physiology and Pharmacology, University of Bristol, Dorothy Hodgkin Building, Bristol BS1 3NY, UK
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Lucas SJ, Bortolotto ZA, Collingridge GL, Lodge D. Selective activation of either mGlu2 or mGlu3 receptors can induce LTD in the amygdala. Neuropharmacology 2012; 66:196-201. [PMID: 22531751 DOI: 10.1016/j.neuropharm.2012.04.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Revised: 03/15/2012] [Accepted: 04/02/2012] [Indexed: 11/18/2022]
Abstract
Group II metabotropic glutamate (mGlu) receptors are known to induce a long-term depression (LTD) of synaptic transmission in many brain regions including the amygdala. However the roles of the individual receptor subtypes, mGlu2 and mGlu3, in LTD are not well understood. In particular, it is unclear whether activation of mGlu3 receptors is sufficient to induce LTD at synapses in the CNS. In the present study, advantage was taken of a Wistar rat strain not expressing mGlu2 receptors (Ceolin et al., 2011) to investigate the function of mGlu3 receptors in the amygdala. In this preparation, the group II agonist, DCG-IV induced an LTD of the cortical, but not the intra-nuclear, synaptic input to the lateral amygdala. This LTD was concentration dependent and was blocked by the group II mGlu receptor antagonist, LY341495. To investigate further the role of mGlu3 receptors, we used LY395756 (an mGlu2 agonist and mGlu3 antagonist), which acts as a pure mGlu3 receptor antagonist in this rat strain. This compound alone had no effect on basal synaptic transmission, but blocked the LTD induced by DCG-IV. Furthermore, we found that DCG-IV also induces LTD in mGlu2 receptor knock-out (KO) mice to a similar extent as in wild-type mice. This confirms that the activation of mGlu3 receptors alone is sufficient to induce LTD at this amygdala synapse. To address whether mGlu2 activation alone is also sufficient to induce LTD at this synapse we used LY541850 (the active enantiomer of LY395756) in wild-type mice. LY541850 induced a substantial LTD showing that either receptor alone is capable of inducing LTD in this pathway. This article is part of a Special Issue entitled 'Metabotropic Glutamate Receptors'.
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Affiliation(s)
- Sarah J Lucas
- MRC Centre for Synaptic Plasticity, University of Bristol, Bristol BS8 1TD, UK.
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