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Apuschkin M, Burm HB, Schmidt JH, Skov LJ, Andersen RC, Bowin CF, Støier JF, Jensen KL, Posselt LP, Dmytriyeva O, Sørensen AT, Egerod KL, Holst B, Rickhag M, Schwartz TW, Gether U. An atlas of GPCRs in dopamine neurons: Identification of the free fatty acid receptor 4 as a regulator of food and water intake. Cell Rep 2024; 43:114509. [PMID: 39003735 DOI: 10.1016/j.celrep.2024.114509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 04/03/2024] [Accepted: 06/28/2024] [Indexed: 07/16/2024] Open
Abstract
Midbrain dopaminergic neurons (DANs) are subject to extensive metabotropic regulation, but the repertoire of G protein-coupled receptors (GPCRs) present in these neurons has not been mapped. Here, we isolate DANs from Dat-eGFP mice to generate a GPCR atlas by unbiased qPCR array expression analysis of 377 GPCRs. Combined with data mining of scRNA-seq databases, we identify multiple receptors in DAN subpopulations with 38 of these receptors representing the majority of transcripts. We identify 41 receptors expressed in midbrain DANs but not in non-DAN midbrain cells, including the free fatty acid receptor 4 (FFAR4). Functional expression of FFAR4 is validated by ex vivo Ca2+ imaging, and in vivo experiments support that FFAR4 negatively regulates food and water intake and bodyweight. In addition to providing a critical framework for understanding metabotropic DAN regulation, our data suggest fatty acid sensing by FFAR4 as a mechanism linking high-energy intake to the dopamine-reward pathway.
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Affiliation(s)
- Mia Apuschkin
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Hayley B Burm
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Jan H Schmidt
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Louise J Skov
- Novo Nordic Foundation Center for Basic Metabolic Research, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Rita C Andersen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Carl-Fredrik Bowin
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark; Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Jonatan F Støier
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Kathrine L Jensen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Leonie P Posselt
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Oksana Dmytriyeva
- Novo Nordic Foundation Center for Basic Metabolic Research, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Andreas T Sørensen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Kristoffer L Egerod
- Novo Nordic Foundation Center for Basic Metabolic Research, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Birgitte Holst
- Department of Biomedical Sciences, Laboratory for Molecular Pharmacology and Novo Nordic Foundation Center for Basic Metabolic Research, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Mattias Rickhag
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark; Danish Research Centre for Magnetic Resonance (DRCMR), Copenhagen University Hospital Amager and Hvidovre, Hvidovre, Denmark
| | - Thue W Schwartz
- Novo Nordic Foundation Center for Basic Metabolic Research, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Ulrik Gether
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark.
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2
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Rabeh N, Hajjar B, Maraka JO, Sammanasunathan AF, Khan M, Alkhaaldi SMI, Mansour S, Almheiri RT, Hamdan H, Abd-Elrahman KS. Targeting mGluR group III for the treatment of neurodegenerative diseases. Biomed Pharmacother 2023; 168:115733. [PMID: 37862967 DOI: 10.1016/j.biopha.2023.115733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 10/11/2023] [Accepted: 10/13/2023] [Indexed: 10/22/2023] Open
Abstract
Glutamate, an excitatory neurotransmitter, is essential for neuronal function, and it acts on ionotropic or metabotropic glutamate receptors (mGluRs). A disturbance in glutamatergic signaling is a hallmark of many neurodegenerative diseases. Developing disease-modifying treatments for neurodegenerative diseases targeting glutamate receptors is a promising avenue. The understudied group III mGluR 4, 6-8 are commonly found in the presynaptic membrane, and their activation inhibits glutamate release. Thus, targeted mGluRs therapies could aid in treating neurodegenerative diseases. This review describes group III mGluRs and their pharmacological ligands in the context of amyotrophic lateral sclerosis, Parkinson's, Alzheimer's, and Huntington's diseases. Attempts to evaluate the efficacy of these drugs in clinical trials are also discussed. Despite a growing list of group III mGluR-specific pharmacological ligands, research on the use of these drugs in neurodegenerative diseases is limited, except for Parkinson's disease. Future efforts should focus on delineating the contribution of group III mGluR to neurodegeneration and developing novel ligands with superior efficacy and a favorable side effect profile for the treatment of neurodegenerative diseases.
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Affiliation(s)
- Nadia Rabeh
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates; Department of Anesthesiology, Pharmacology and Therapeutics, and Djavad Mowafaghian Center for Brain Health, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Baraa Hajjar
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates
| | - Jude O Maraka
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates
| | - Ashwin F Sammanasunathan
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates
| | - Mohammed Khan
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates
| | - Saif M I Alkhaaldi
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates
| | - Samy Mansour
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates
| | - Rashed T Almheiri
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates
| | - Hamdan Hamdan
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates; Healthcare Engineering Innovation Center (HEIC), Khalifa University of Science and Technology, Abu Dhabi 127788, United Arab Emirates
| | - Khaled S Abd-Elrahman
- Department of Anesthesiology, Pharmacology and Therapeutics, and Djavad Mowafaghian Center for Brain Health, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada; Department of Pharmacology and Therapeutics, College of Medicine and Health Science, Khalifa University, Abu Dhabi 127788, United Arab Emirates; Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria 21521, Egypt.
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3
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de Ceglia R, Ledonne A, Litvin DG, Lind BL, Carriero G, Latagliata EC, Bindocci E, Di Castro MA, Savtchouk I, Vitali I, Ranjak A, Congiu M, Canonica T, Wisden W, Harris K, Mameli M, Mercuri N, Telley L, Volterra A. Specialized astrocytes mediate glutamatergic gliotransmission in the CNS. Nature 2023; 622:120-129. [PMID: 37674083 PMCID: PMC10550825 DOI: 10.1038/s41586-023-06502-w] [Citation(s) in RCA: 50] [Impact Index Per Article: 50.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 07/31/2023] [Indexed: 09/08/2023]
Abstract
Multimodal astrocyte-neuron communications govern brain circuitry assembly and function1. For example, through rapid glutamate release, astrocytes can control excitability, plasticity and synchronous activity2,3 of synaptic networks, while also contributing to their dysregulation in neuropsychiatric conditions4-7. For astrocytes to communicate through fast focal glutamate release, they should possess an apparatus for Ca2+-dependent exocytosis similar to neurons8-10. However, the existence of this mechanism has been questioned11-13 owing to inconsistent data14-17 and a lack of direct supporting evidence. Here we revisited the astrocyte glutamate exocytosis hypothesis by considering the emerging molecular heterogeneity of astrocytes18-21 and using molecular, bioinformatic and imaging approaches, together with cell-specific genetic tools that interfere with glutamate exocytosis in vivo. By analysing existing single-cell RNA-sequencing databases and our patch-seq data, we identified nine molecularly distinct clusters of hippocampal astrocytes, among which we found a notable subpopulation that selectively expressed synaptic-like glutamate-release machinery and localized to discrete hippocampal sites. Using GluSnFR-based glutamate imaging22 in situ and in vivo, we identified a corresponding astrocyte subgroup that responds reliably to astrocyte-selective stimulations with subsecond glutamate release events at spatially precise hotspots, which were suppressed by astrocyte-targeted deletion of vesicular glutamate transporter 1 (VGLUT1). Furthermore, deletion of this transporter or its isoform VGLUT2 revealed specific contributions of glutamatergic astrocytes in cortico-hippocampal and nigrostriatal circuits during normal behaviour and pathological processes. By uncovering this atypical subpopulation of specialized astrocytes in the adult brain, we provide insights into the complex roles of astrocytes in central nervous system (CNS) physiology and diseases, and identify a potential therapeutic target.
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Affiliation(s)
- Roberta de Ceglia
- Department of Fundamental Neuroscience, University of Lausanne, Lausanne, Switzerland
| | - Ada Ledonne
- Department of Fundamental Neuroscience, University of Lausanne, Lausanne, Switzerland
- Department of Experimental Neuroscience, IRCCS Santa Lucia Foundation, Rome, Italy
| | - David Gregory Litvin
- Department of Fundamental Neuroscience, University of Lausanne, Lausanne, Switzerland
- Wyss Center for Bio and Neuro Engineering, Campus Biotech, Geneva, Switzerland
| | - Barbara Lykke Lind
- Department of Fundamental Neuroscience, University of Lausanne, Lausanne, Switzerland
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Giovanni Carriero
- Department of Fundamental Neuroscience, University of Lausanne, Lausanne, Switzerland
| | | | - Erika Bindocci
- Department of Fundamental Neuroscience, University of Lausanne, Lausanne, Switzerland
| | | | - Iaroslav Savtchouk
- Department of Fundamental Neuroscience, University of Lausanne, Lausanne, Switzerland
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, USA
| | - Ilaria Vitali
- Department of Fundamental Neuroscience, University of Lausanne, Lausanne, Switzerland
| | - Anurag Ranjak
- Department of Fundamental Neuroscience, University of Lausanne, Lausanne, Switzerland
| | - Mauro Congiu
- Department of Fundamental Neuroscience, University of Lausanne, Lausanne, Switzerland
| | - Tara Canonica
- Department of Fundamental Neuroscience, University of Lausanne, Lausanne, Switzerland
| | - William Wisden
- Department of Life Sciences and UK Dementia Research Institute, Imperial College London, London, UK
| | - Kenneth Harris
- UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Manuel Mameli
- Department of Fundamental Neuroscience, University of Lausanne, Lausanne, Switzerland
| | - Nicola Mercuri
- Department of Experimental Neuroscience, IRCCS Santa Lucia Foundation, Rome, Italy
- Department of Systems Medicine, University of Rome "Tor Vergata", Rome, Italy
| | - Ludovic Telley
- Department of Fundamental Neuroscience, University of Lausanne, Lausanne, Switzerland.
| | - Andrea Volterra
- Department of Fundamental Neuroscience, University of Lausanne, Lausanne, Switzerland.
- Wyss Center for Bio and Neuro Engineering, Campus Biotech, Geneva, Switzerland.
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4
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Bourque M, Morissette M, Conquet F, Charvin D, Di Paolo T. Foliglurax, a positive allosteric modulator of the metabotrophic glutamate receptor 4, protects dopaminergic neurons in MPTP-lesioned male mice. Brain Res 2023; 1809:148349. [PMID: 36972837 DOI: 10.1016/j.brainres.2023.148349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 03/20/2023] [Accepted: 03/24/2023] [Indexed: 03/28/2023]
Abstract
Overactivity of the corticostriatal glutamatergic pathway is documented in Parkinson's disease (PD) and stimulation of presynaptic metabotropic glutamate (mGlu) receptors 4 on these striatal afferents inhibits glutamate release normalizing neuronal activity in the basal ganglia. Moreover, mGlu4 receptors are also expressed in glial cells and are able to modulate glial function making this receptor a potential target for neuroprotection. Hence, we investigated whether foliglurax, a positive allosteric modulator of mGlu4 receptors with high brain exposure after oral administration, has neuroprotective effects in MPTP mice to model early PD. Male mice were treated daily from day 1 to 10 with 1, 3 or 10 mg/kg of foliglurax and administered MPTP on the 5th day then euthanized on the 11th day. Dopamine neuron integrity was assessed with measures of striatal dopamine and its metabolites levels, striatal and nigral dopamine transporter (DAT) binding and inflammation with markers of striatal astrocytes (GFAP) and microglia (Iba1). MPTP lesion produced a decrease in dopamine, its metabolites and striatal DAT specific binding that was prevented by treatment with 3 mg/kg of foliglurax, whereas 1 and 10 mg/kg had no beneficial effect. MPTP mice had increased levels of GFAP; foliglurax treatment (3 mg/kg) prevented this increase. Iba1 levels were unchanged in MPTP mice compared to control mice. There was a negative correlation between dopamine content and GFAP levels. Our results show that positive allosteric modulation of mGlu4 receptors with foliglurax provided neuroprotective effects in the MPTP mouse model of PD.
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Affiliation(s)
- Mélanie Bourque
- Centre de Recherche du CHU de Québec, Axe Neurosciences, Québec, QC G1V4G2, Canada
| | - Marc Morissette
- Centre de Recherche du CHU de Québec, Axe Neurosciences, Québec, QC G1V4G2, Canada
| | | | | | - Thérèse Di Paolo
- Centre de Recherche du CHU de Québec, Axe Neurosciences, Québec, QC G1V4G2, Canada; Faculté de Pharmacie, Pavillon Ferdinand-Vandry, Université Laval, Québec, QC G1V 0A6, Canada.
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5
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Hoglund BK, Carfagno V, Olive MF, Leyrer-Jackson JM. Metabotropic glutamate receptors and cognition: From underlying plasticity and neuroprotection to cognitive disorders and therapeutic targets. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2023; 168:367-413. [PMID: 36868635 DOI: 10.1016/bs.irn.2022.10.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Metabotropic glutamate (mGlu) receptors are G protein-coupled receptors that play pivotal roles in mediating the activity of neurons and other cell types within the brain, communication between cell types, synaptic plasticity, and gene expression. As such, these receptors play an important role in a number of cognitive processes. In this chapter, we discuss the role of mGlu receptors in various forms of cognition and their underlying physiology, with an emphasis on cognitive dysfunction. Specifically, we highlight evidence that links mGlu physiology to cognitive dysfunction across brain disorders including Parkinson's disease, Alzheimer's disease, Fragile X syndrome, post-traumatic stress disorder, and schizophrenia. We also provide recent evidence demonstrating that mGlu receptors may elicit neuroprotective effects in particular disease states. Lastly, we discuss how mGlu receptors can be targeted utilizing positive and negative allosteric modulators as well as subtype specific agonists and antagonist to restore cognitive function across these disorders.
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Affiliation(s)
- Brandon K Hoglund
- Department of Medical Education, School of Medicine, Creighton University, Phoenix, AZ, United States
| | - Vincent Carfagno
- School of Medicine, Midwestern University, Glendale, AZ, United States
| | - M Foster Olive
- Department of Psychology, Arizona State University, Tempe, AZ, United States
| | - Jonna M Leyrer-Jackson
- Department of Medical Education, School of Medicine, Creighton University, Phoenix, AZ, United States.
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6
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Borsani E, Bonomini F, Bonini SA, Premoli M, Maccarinelli G, Giugno L, Mastinu A, Aria F, Memo M, Rezzani R. Role of melatonin in autism spectrum disorders in a male murine transgenic model: Study in the prefrontal cortex. J Neurosci Res 2022; 100:780-797. [PMID: 35043490 DOI: 10.1002/jnr.24997] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 10/16/2021] [Accepted: 11/11/2021] [Indexed: 12/15/2022]
Abstract
Autism spectrum disorders (ASDs) are a group of clinically heterogeneous neurodevelopmental disorders sharing common features related to impaired social and communication abilities in addition to stereotyped behaviors. ASD patients present encephalic morphological, physiological, and biomolecular alterations with low levels of melatonin due to alterations in its pathways. Therefore, even if ASDs have traditionally been framed as behavioral disorders, several lines of evidence are accumulating that ASDs are characterized by certain anatomical and physiological abnormalities, including oxidative stress and inflammation in peripheral biomarkers, but likewise present in human brain tissue also characterized by alterations in synaptic remodeling and neuromodulation. Melatonin has also protective and antioxidant properties, so we can therefore hypothesize that alterations in melatonin's pathways may be one of the causes of the symptomatology of autism. The aim of the present study was to analyze the beneficial effect induced by melatonin administration and its possible mechanism of action in a transgenic mouse model of autism, immediately after weaning. The male mice were daily treated per os with melatonin (10 mg/Kg/day) or vehicle for 8 weeks starting from the sixth week of life. The antioxidant modulation, the GABAergic/glutamatergic impairment, and the synaptic remodeling in the prefrontal cortex have been evaluated. Social and repetitive behaviors were also evaluated. The behavioral results showed no statistical evidences, instead the immunohistochemical results indicated the ability of melatonin to promote the activity of antioxidant system, the GABAergic/glutamatergic equilibrium, and the synaptic remodeling. The results show that melatonin may be a possible adjuvant therapeutic strategy in ASDs.
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Affiliation(s)
- Elisa Borsani
- Division of Anatomy and Physiopathology, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy
- Interdipartimental University Center of Research "Adaption and Regeneration of Tissues and Organs-(ARTO)", University of Brescia, Brescia, Italy
| | - Francesca Bonomini
- Division of Anatomy and Physiopathology, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy
- Interdipartimental University Center of Research "Adaption and Regeneration of Tissues and Organs-(ARTO)", University of Brescia, Brescia, Italy
| | - Sara Anna Bonini
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Marika Premoli
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Giuseppina Maccarinelli
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Lorena Giugno
- Division of Anatomy and Physiopathology, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy
| | - Andrea Mastinu
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Francesca Aria
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Maurizio Memo
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Rita Rezzani
- Division of Anatomy and Physiopathology, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy
- Interdipartimental University Center of Research "Adaption and Regeneration of Tissues and Organs-(ARTO)", University of Brescia, Brescia, Italy
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7
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Piszczek L, Constantinescu A, Kargl D, Lazovic J, Pekcec A, Nicholson JR, Haubensak W. Dissociation of impulsive traits by subthalamic metabotropic glutamate receptor 4. eLife 2022; 11:62123. [PMID: 34982027 PMCID: PMC8803315 DOI: 10.7554/elife.62123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 12/31/2021] [Indexed: 11/17/2022] Open
Abstract
Behavioral strategies require gating of premature responses to optimize outcomes. Several brain areas control impulsive actions, but the neuronal basis of natural variation in impulsivity between individuals remains largely unknown. Here, by combining a Go/No-Go behavioral assay with resting-state (rs) functional MRI in mice, we identified the subthalamic nucleus (STN), a known gate for motor control in the basal ganglia, as a major hotspot for trait impulsivity. In vivo recorded STN neural activity encoded impulsive action as a separable state from basic motor control, characterized by decoupled STN/substantia nigra pars reticulata (SNr) mesoscale networks. Optogenetic modulation of STN activity bidirectionally controlled impulsive behavior. Pharmacological and genetic manipulations showed that these impulsive actions are modulated by metabotropic glutamate receptor 4 (mGlu4) function in STN and its coupling to SNr in a behavioral trait-dependent manner, and independently of general motor function. In conclusion, STN circuitry multiplexes motor control and trait impulsivity, which are molecularly dissociated by mGlu4. This provides a potential mechanism for the genetic modulation of impulsive behavior, a clinically relevant predictor for developing psychiatric disorders associated with impulsivity.
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Affiliation(s)
- Lukasz Piszczek
- The Research Institute of Molecular Pathology (IMP), Department of Neuroscience, Vienna Biocenter, Vienna, Austria
| | - Andreea Constantinescu
- The Research Institute of Molecular Pathology (IMP), Department of Neuroscience, Vienna Biocenter, Vienna, Austria
| | - Dominic Kargl
- The Research Institute of Molecular Pathology (IMP), Department of Neuroscience, Vienna Biocenter, Vienna, Austria.,Department of Neuronal Cell Biology, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Jelena Lazovic
- Preclinical Imaging Facility, Vienna BioCenter Core Facilities (VBCF), Vienna, Austria
| | - Anton Pekcec
- Div Research Germany, Boehringer Ingelheim, Biberach an der Riss, Germany
| | - Janet R Nicholson
- Div Research Germany, Boehringer Ingelheim, Biberach an der Riss, Germany
| | - Wulf Haubensak
- The Research Institute of Molecular Pathology (IMP), Department of Neuroscience, Vienna Biocenter, Vienna, Austria.,Department of Neuronal Cell Biology, Center for Brain Research, Medical University of Vienna, Vienna, Austria
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8
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Mann E, Jackson M, Lincoln L, Fisher R, Rose S, Duty S. Antiparkinsonian Effects of a Metabotropic Glutamate Receptor 4 Agonist in MPTP-Treated Marmosets. JOURNAL OF PARKINSONS DISEASE 2021; 10:959-967. [PMID: 32250315 DOI: 10.3233/jpd-191824] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND Increased firing across glutamatergic synapses may contribute to both the motor dysfunction and L-DOPA-induced dyskinesia seen in Parkinson's disease. Given their ability to reduce glutamate release, activation of group III metabotropic glutamate receptors such as metabotropic glutamate receptor 4 may prove effective against both motor dysfunction and dyskinesia in Parkinson's disease. OBJECTIVE We hypothesised that activation of metabotropic glutamate receptor 4 by an orthosteric agonist ((2S)-2-amino-4-(hydroxy(hydroxy(4-hydroxy-3-methoxy-5-nitrophenyl)methyl)phosphoryl)butanoic acid, LSP1-2111) would produce antiparkinsonian activity and reduce expression of dyskinesia in a 1-methyl-4-phenyl,1,2,3,6-tetrahydropyridine (MPTP)-treated marmoset model of Parkinson's disease. METHODS Common marmosets were previously treated with MPTP and pre-primed with L-DOPA for up to 28 days to express dyskinesia. LSP1-2111 (1, 3, or 6 mg/kg s.c.) or vehicle (0.9% saline s.c.) were administered immediately prior to L-DOPA (8 mg/kg + benserazide (10 mg/kg) p.o.) or vehicle (10% sucrose p.o.). Locomotor activity was measured in automated test cages and animals were scored for dyskinesia and disability. RESULTS As expected, L-DOPA reversed motor disability and induced moderate dyskinesia. By contrast, LSP1-2111 alone significantly reduced the motor disability without any accompanying expression of dyskinesia. When administered in combination with L-DOPA, LSP1-2111 did not significantly reduce the severity of L-DOPA-induced dyskinesia. CONCLUSION Systemic administration of LSP1-2111 reduces motor disability without causing dyskinesia in MPTP-treated marmosets, supporting a role for metabotropic glutamate receptor 4 orthosteric agonists as promising monotherapy for PD. Conversely, this study found no evidence to support their use as antidyskinetic agents within the dose range tested.
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Affiliation(s)
- Elizabeth Mann
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Michael Jackson
- Neurodegenerative Diseases Research Group, Faculty of Life Science and Medicine, King's College London, London, UK
| | - Louise Lincoln
- Neurodegenerative Diseases Research Group, Faculty of Life Science and Medicine, King's College London, London, UK
| | - Ria Fisher
- Neurodegenerative Diseases Research Group, Faculty of Life Science and Medicine, King's College London, London, UK
| | - Sarah Rose
- Neurodegenerative Diseases Research Group, Faculty of Life Science and Medicine, King's College London, London, UK
| | - Susan Duty
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
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9
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Wang J, Qu X, Shoup TM, Yuan G, Afshar S, Pan C, Zhu A, Choi JK, Kang HJ, Poutiainen P, ElFakhri G, Zhang Z, Brownell AL. Synthesis and Characterization of Fluorine-18-Labeled N-(4-Chloro-3-((fluoromethyl- d2)thio)phenyl)picolinamide for Imaging of mGluR4 in Brain. J Med Chem 2020; 63:3381-3389. [PMID: 32081008 PMCID: PMC7261135 DOI: 10.1021/acs.jmedchem.0c00201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We have synthesized and characterized [18F]-N-(4-chloro-3-((fluoromethyl-d2)thio)phenyl)-picolinamide ([18F]15) as a potential ligand for the positron emission tomography (PET) imaging of mGluR4 in the brain. Radioligand [18F]15 displays central nervous system drug-like properties, including mGluR4 affinity, potent mGluR4 PAM activity, and selectivity against other mGluRs, as well as sufficient metabolic stability. Radiosynthesis was carried out in two steps. The radiochemical yield of [18F]15 was 11.6 ± 2.9% (n = 7, decay corrected) with a purity of 99% and a molar activity of 84.1 ± 11.8 GBq/μmol. Ex vivo biodistribution studies showed reversible binding of [18F]15 in all investigated tissues including the brain, liver, heart, lungs, and kidneys. PET imaging studies in male Sprague Dawley rats showed that [18F]15 accumulates in the brain regions known to express mGluR4. Pretreatment with the unlabeled mGluR4 PAM compounds 13 (methylthio analogue) and 15 showed significant dose-dependent blocking effects. These results suggest that [18F]15 is a promising radioligand for PET imaging mGluR4 in the brain.
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Affiliation(s)
- Junfeng Wang
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 125 Nashua Street, Suite 660, Boston, MA 02114
| | - Xiying Qu
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 125 Nashua Street, Suite 660, Boston, MA 02114
| | - Timothy M. Shoup
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 125 Nashua Street, Suite 660, Boston, MA 02114
| | - Gengyang Yuan
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 125 Nashua Street, Suite 660, Boston, MA 02114
| | - Sepideh Afshar
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 125 Nashua Street, Suite 660, Boston, MA 02114
| | - Chuzhi Pan
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 125 Nashua Street, Suite 660, Boston, MA 02114
- The Third Affiliated Hospital of Sun Yat-sen University, 510630, China
| | - Aijun Zhu
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 125 Nashua Street, Suite 660, Boston, MA 02114
| | - Ji-Kyung Choi
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, 149 Thirteenth Street, Suite 2301 Charlestown, MA 02129
| | - Hye Jin Kang
- Department of Pharmacology, University of North Carolina Chapel Hill School of Medicine, Chapel Hill, North Carolina 27514, United States
| | | | - Georges ElFakhri
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 125 Nashua Street, Suite 660, Boston, MA 02114
| | - Zhaoda Zhang
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, 149 Thirteenth Street, Suite 2301 Charlestown, MA 02129
| | - Anna-Liisa Brownell
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 125 Nashua Street, Suite 660, Boston, MA 02114
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10
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Wang J, Shoup TM, Brownell AL, Zhang Z. Improved Synthesis of the Thiophenol Precursor N-(4-Chloro-3-mercaptophenyl)picolinamide for Making the mGluR4 PET Ligand. Tetrahedron 2019; 75:3917-3922. [PMID: 32831413 PMCID: PMC7442123 DOI: 10.1016/j.tet.2019.06.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Recently [11C]mG4P012 (previously [11C]KALB012 and presently named as [11C]PXT012253 by Prexton Therapeutics) had been used as a biomarker during the preclinical development of a potential therapeutic drug, PXT0002331 (an mGluR4 PAM), for PD and L-dopa-induced dyskinesia. [11C]mG4P012 was shown to be a promising PET radioligand for mGluR4 in the monkey brain and for further development in human subjects. However, the previously reported multi-step synthesis of the thiophenol precursor suffered from low yields and difficult workup procedures. To support the translational research of [11C]mG4P012 and the other potential applications, we have developed a new route for synthesis of the thiophenol precursor and optimized the reaction conditions. The synthesis of N-(4-chloro-3-mercaptophenyl)picolinamide from 1-chloro-4-nitrobenzene has been greatly improved from 8% to 52% total yield with easy handling and in gram scales.
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Affiliation(s)
- Junfeng Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, 149 Thirteenth Street, Suite 2301 Charlestown, MA 02129
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 125 Nashua Street, Suite 660, Boston, MA 02114
| | - Timothy M. Shoup
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 125 Nashua Street, Suite 660, Boston, MA 02114
| | - Anna-Liisa Brownell
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 125 Nashua Street, Suite 660, Boston, MA 02114
| | - Zhaoda Zhang
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, 149 Thirteenth Street, Suite 2301 Charlestown, MA 02129
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11
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Avdeeva NV, Sidorova SA, Gudyrev OS, Osipova OA, Golubev IV. Mechanism of neuroprotective effect of mGluR4 agonists. RESEARCH RESULTS IN PHARMACOLOGY 2019. [DOI: 10.3897/rrpharmacology.5.36565] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Introduction: This review of literature is to demonstrate a role of group III metabotropic glutamate receptors in maintaining the level of extracellular glutamate in ischemic stroke and neurodegenerative diseases.
Metabotropic glutamate receptors: mGluRs are classified into three groups. It is suggested that the activation of mGluR4 may have a neuroprotective effect.
Role of excitotoxicity in the development and severity of various brain diseases: An increase in the concentration of intracellular Ca2+ is the result of excessive accumulation of glutamate in the extracellular space. And a death of nerve cells occurs after a sequence of biochemical reactions, which was called excitotoxicity. It is followed by an imbalance between glutamatergic excitation and GABA-ergic inhibition. As a result of untimely activation of the inhibitory mechanisms, the accumulation of extracellular glutamate, and consequently the death of neurons, continues, which leads to more severe manifestations of the cerebral ischemia.
Role of modulation of mGluRs activity in neuroprotection: The literature describes a large number of studies proving that inhibition of hyperactive glutamatergic transmission has a neuroprotective effect. The most likely mechanisms of neuroprotection are inhibition of glutamate production in the substantia nigra, which in turn protects against glutamate-mediated excitotoxicity, and the reduction of the inflammatory effects.
Anti-inflammatory effect of mGluR4 agonists in the mechanism of neuroprotective action: The astroglial component may contribute to the protective action of mGluR4 modulators, since astrocytes and microglia have mGluR4.
Conclusion: mGluR4 agonists have the neuroprotective and anti-inflammatory effects.
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12
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Bollinger SR, Engers DW, Panarese JD, West M, Engers JL, Loch MT, Rodriguez AL, Blobaum AL, Jones CK, Thompson Gray A, Conn PJ, Lindsley CW, Niswender CM, Hopkins CR. Discovery, Structure-Activity Relationship, and Biological Characterization of a Novel Series of 6-((1 H-Pyrazolo[4,3- b]pyridin-3-yl)amino)-benzo[ d]isothiazole-3-carboxamides as Positive Allosteric Modulators of the Metabotropic Glutamate Receptor 4 (mGlu 4). J Med Chem 2018; 62:342-358. [PMID: 30247901 DOI: 10.1021/acs.jmedchem.8b00994] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
This work describes the discovery and characterization of novel 6-(1 H-pyrazolo[4,3- b]pyridin-3-yl)amino-benzo[ d]isothiazole-3-carboxamides as mGlu4 PAMs. This scaffold provides improved metabolic clearance and CYP1A2 profiles compared to previously discovered mGlu4 PAMs. From this work, 27o (VU6001376) was identified as a potent (EC50 = 50.1 nM, 50.5% GluMax) and selective mGlu4 PAM with an excellent rat DMPK profile ( in vivo rat CLp = 3.1 mL/min/kg, t1/2 = 445 min, CYP1A2 IC50 > 30 μM). Compound 27o was also active in reversing haloperidol induced catalepsy in a rodent preclinical model of Parkinson's disease.
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Affiliation(s)
- Sean R Bollinger
- Vanderbilt Center for Neuroscience Drug Discovery , Vanderbilt University , Nashville , Tennessee 37232 , United States.,Department of Pharmacology , Vanderbilt University , Nashville , Tennessee 37232 , United States
| | - Darren W Engers
- Vanderbilt Center for Neuroscience Drug Discovery , Vanderbilt University , Nashville , Tennessee 37232 , United States.,Department of Pharmacology , Vanderbilt University , Nashville , Tennessee 37232 , United States
| | - Joseph D Panarese
- Vanderbilt Center for Neuroscience Drug Discovery , Vanderbilt University , Nashville , Tennessee 37232 , United States.,Department of Pharmacology , Vanderbilt University , Nashville , Tennessee 37232 , United States
| | - Mary West
- Vanderbilt Center for Neuroscience Drug Discovery , Vanderbilt University , Nashville , Tennessee 37232 , United States.,Department of Pharmacology , Vanderbilt University , Nashville , Tennessee 37232 , United States
| | - Julie L Engers
- Vanderbilt Center for Neuroscience Drug Discovery , Vanderbilt University , Nashville , Tennessee 37232 , United States.,Department of Pharmacology , Vanderbilt University , Nashville , Tennessee 37232 , United States
| | - Matthew T Loch
- Vanderbilt Center for Neuroscience Drug Discovery , Vanderbilt University , Nashville , Tennessee 37232 , United States.,Department of Pharmacology , Vanderbilt University , Nashville , Tennessee 37232 , United States
| | - Alice L Rodriguez
- Vanderbilt Center for Neuroscience Drug Discovery , Vanderbilt University , Nashville , Tennessee 37232 , United States.,Department of Pharmacology , Vanderbilt University , Nashville , Tennessee 37232 , United States
| | - Anna L Blobaum
- Vanderbilt Center for Neuroscience Drug Discovery , Vanderbilt University , Nashville , Tennessee 37232 , United States.,Department of Pharmacology , Vanderbilt University , Nashville , Tennessee 37232 , United States
| | - Carrie K Jones
- Vanderbilt Center for Neuroscience Drug Discovery , Vanderbilt University , Nashville , Tennessee 37232 , United States.,Department of Pharmacology , Vanderbilt University , Nashville , Tennessee 37232 , United States
| | - Analisa Thompson Gray
- Vanderbilt Center for Neuroscience Drug Discovery , Vanderbilt University , Nashville , Tennessee 37232 , United States.,Department of Pharmacology , Vanderbilt University , Nashville , Tennessee 37232 , United States
| | - P Jeffrey Conn
- Vanderbilt Center for Neuroscience Drug Discovery , Vanderbilt University , Nashville , Tennessee 37232 , United States.,Department of Pharmacology , Vanderbilt University , Nashville , Tennessee 37232 , United States.,Vanderbilt Kennedy Center , Vanderbilt University Medical Center , Nashville , Tennessee 37232 , United States
| | - Craig W Lindsley
- Vanderbilt Center for Neuroscience Drug Discovery , Vanderbilt University , Nashville , Tennessee 37232 , United States.,Department of Pharmacology , Vanderbilt University , Nashville , Tennessee 37232 , United States.,Department of Chemistry , Vanderbilt University , Nashville , Tennessee 37232 , United States.,Department of Biochemistry , Vanderbilt University , Nashville , Tennessee 37232 , United States
| | - Colleen M Niswender
- Vanderbilt Center for Neuroscience Drug Discovery , Vanderbilt University , Nashville , Tennessee 37232 , United States.,Department of Pharmacology , Vanderbilt University , Nashville , Tennessee 37232 , United States.,Vanderbilt Kennedy Center , Vanderbilt University Medical Center , Nashville , Tennessee 37232 , United States
| | - Corey R Hopkins
- Vanderbilt Center for Neuroscience Drug Discovery , Vanderbilt University , Nashville , Tennessee 37232 , United States.,Department of Pharmacology , Vanderbilt University , Nashville , Tennessee 37232 , United States.,Department of Chemistry , Vanderbilt University , Nashville , Tennessee 37232 , United States
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13
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Masilamoni GJ, Smith Y. Metabotropic glutamate receptors: targets for neuroprotective therapies in Parkinson disease. Curr Opin Pharmacol 2018; 38:72-80. [PMID: 29605730 DOI: 10.1016/j.coph.2018.03.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Accepted: 03/12/2018] [Indexed: 01/22/2023]
Abstract
Metabotropic glutamate receptors (mGluRs) are heavily expressed throughout the basal ganglia (BG), where they modulate neuronal excitability, transmitter release and long term synaptic plasticity. Therefore, targeting specific mGluR subtypes by means of selective drugs could be a possible strategy for restoring normal synaptic function and neuronal activity of the BG in Parkinson disease (PD). Preclinical studies have revealed that specific mGluR subtypes mediate significant neuroprotective effects that reduce toxin-induced midbrain dopaminergic neuronal death in animal models of PD. Although the underlying mechanisms of these effects must be further studied, there is evidence that intracellular calcium regulation, anti-inflammatory effects, and glutamatergic network modulation contribute to some of these neuroprotective properties. It is noteworthy that these protective effects extend beyond midbrain dopaminergic neurons to include other monoaminergic cell groups for some mGluRs. In this review, we discuss evidence for mGluR-mediated neuroprotection in PD and highlight the challenges to translate these findings into human trials.
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Affiliation(s)
- Gunasingh J Masilamoni
- Yerkes National Primate Research Center, Emory University, 954, Gatewood Rd NE, Atlanta, GA 30322, USA; Udall Center of Excellence for Parkinson's Disease, Emory University, 954, Gatewood Rd NE, Atlanta, GA 30322, USA
| | - Yoland Smith
- Yerkes National Primate Research Center, Emory University, 954, Gatewood Rd NE, Atlanta, GA 30322, USA; Department of Neurology, Emory University, 954, Gatewood Rd NE, Atlanta, GA 30322, USA; Udall Center of Excellence for Parkinson's Disease, Emory University, 954, Gatewood Rd NE, Atlanta, GA 30322, USA.
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14
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Mellone M, Gardoni F. Glutamatergic mechanisms in l-DOPA-induced dyskinesia and therapeutic implications. J Neural Transm (Vienna) 2018; 125:1225-1236. [DOI: 10.1007/s00702-018-1846-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Accepted: 01/23/2018] [Indexed: 02/01/2023]
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15
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Steinkellner T, Zell V, Farino ZJ, Sonders MS, Villeneuve M, Freyberg RJ, Przedborski S, Lu W, Freyberg Z, Hnasko TS. Role for VGLUT2 in selective vulnerability of midbrain dopamine neurons. J Clin Invest 2018; 128:774-788. [PMID: 29337309 DOI: 10.1172/jci95795] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 11/21/2017] [Indexed: 12/22/2022] Open
Abstract
Parkinson's disease is characterized by the loss of dopamine (DA) neurons in the substantia nigra pars compacta (SNc). DA neurons in the ventral tegmental area are more resistant to this degeneration than those in the SNc, though the mechanisms for selective resistance or vulnerability remain poorly understood. A key to elucidating these processes may lie within the subset of DA neurons that corelease glutamate and express the vesicular glutamate transporter VGLUT2. Here, we addressed the potential relationship between VGLUT expression and DA neuronal vulnerability by overexpressing VGLUT in DA neurons of flies and mice. In Drosophila, VGLUT overexpression led to loss of select DA neuron populations. Similarly, expression of VGLUT2 specifically in murine SNc DA neurons led to neuronal loss and Parkinsonian behaviors. Other neuronal cell types showed no such sensitivity, suggesting that DA neurons are distinctively vulnerable to VGLUT2 expression. Additionally, most DA neurons expressed VGLUT2 during development, and coexpression of VGLUT2 with DA markers increased following injury in the adult. Finally, conditional deletion of VGLUT2 made DA neurons more susceptible to Parkinsonian neurotoxins. These data suggest that the balance of VGLUT2 expression is a crucial determinant of DA neuron survival. Ultimately, manipulation of this VGLUT2-dependent process may represent an avenue for therapeutic development.
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Affiliation(s)
| | - Vivien Zell
- Department of Neurosciences, UCSD, La Jolla, California, USA
| | - Zachary J Farino
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | | | - Michael Villeneuve
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Robin J Freyberg
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Serge Przedborski
- Department of Neurology, and.,Department of Pathology and Cell Biology, Columbia University, New York, New York, USA
| | - Wei Lu
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, Maryland, USA
| | - Zachary Freyberg
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.,Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Thomas S Hnasko
- Department of Neurosciences, UCSD, La Jolla, California, USA
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16
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Niswender CM, Jones CK, Lin X, Bubser M, Gray AT, Blobaum AL, Engers DW, Rodriguez AL, Loch MT, Daniels JS, Lindsley CW, Hopkins CR, Javitch JA, Conn PJ. Development and Antiparkinsonian Activity of VU0418506, a Selective Positive Allosteric Modulator of Metabotropic Glutamate Receptor 4 Homomers without Activity at mGlu2/4 Heteromers. ACS Chem Neurosci 2016; 7:1201-11. [PMID: 27441572 PMCID: PMC5073817 DOI: 10.1021/acschemneuro.6b00036] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Metabotropic glutamate receptor 4 (mGlu4) is emerging as a potential therapeutic target for numerous central nervous system indications, including Parkinson's disease (PD). As the glutamate binding sites among the eight mGlu receptors are highly conserved, modulation of receptor activity via allosteric sites within the receptor transmembrane domains using positive and negative allosteric modulators (PAMs and NAMs, respectively) has become a common strategy. We and others have used PAMs targeting mGlu4 to show that potentiation of receptor signaling induces antiparkinsonian activity in a variety of PD animal models, including haloperidol-induced catalepsy and 6-hydroxydopamine-induced lesion. Recently, mGlu4 has been reported to form heteromeric complexes with other mGlu receptor subtypes, such as mGlu2, and the resulting heteromer exhibits a distinct pharmacological profile in response to allosteric modulators. For example, some mGlu4 PAMs do not appear to potentiate glutamate activity when mGlu2 and mGlu4 are coexpressed, whereas other compounds potentiate mGlu4 responses regardless of mGlu2 coexpression. We report here the discovery and characterization of VU0418506, a novel mGlu4 PAM with activity in rodent PD models. Using pharmacological approaches and Complemented Donor-Acceptor resonance energy transfer (CODA-RET) technology, we find that VU0418506 does not potentiate agonist-induced activity when mGlu2 and mGlu4 are heterodimerized, suggesting that the antiparkinsonian action of mGlu4 PAMs can be induced by compounds without activity at mGlu2/4 heteromers.
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Affiliation(s)
- Colleen M. Niswender
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Kennedy Center, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Carrie K. Jones
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Kennedy Center, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Xin Lin
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, New York 10032, United States
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York 10032, United States
| | - Michael Bubser
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Analisa Thompson Gray
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Anna L. Blobaum
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Darren W. Engers
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Alice L. Rodriguez
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Matthew T. Loch
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - J. Scott Daniels
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Craig W. Lindsley
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Corey R. Hopkins
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Jonathan A Javitch
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, New York 10032, United States
- Department of Pharmacology, Columbia University College of Physicians and Surgeons, New York, New York 10032, United States
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York 10032, United States
| | - P. Jeffrey Conn
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Kennedy Center, Vanderbilt University, Nashville, Tennessee 37232, United States
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17
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Lindsley CW, Emmitte KA, Hopkins CR, Bridges TM, Gregory KJ, Niswender CM, Conn PJ. Practical Strategies and Concepts in GPCR Allosteric Modulator Discovery: Recent Advances with Metabotropic Glutamate Receptors. Chem Rev 2016; 116:6707-41. [PMID: 26882314 PMCID: PMC4988345 DOI: 10.1021/acs.chemrev.5b00656] [Citation(s) in RCA: 135] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Allosteric modulation of GPCRs has initiated a new era of basic and translational discovery, filled with therapeutic promise yet fraught with caveats. Allosteric ligands stabilize unique conformations of the GPCR that afford fundamentally new receptors, capable of novel pharmacology, unprecedented subtype selectivity, and unique signal bias. This review provides a comprehensive overview of the basics of GPCR allosteric pharmacology, medicinal chemistry, drug metabolism, and validated approaches to address each of the major challenges and caveats. Then, the review narrows focus to highlight recent advances in the discovery of allosteric ligands for metabotropic glutamate receptor subtypes 1-5 and 7 (mGlu1-5,7) highlighting key concepts ("molecular switches", signal bias, heterodimers) and practical solutions to enable the development of tool compounds and clinical candidates. The review closes with a section on late-breaking new advances with allosteric ligands for other GPCRs and emerging data for endogenous allosteric modulators.
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Affiliation(s)
- Craig W. Lindsley
- Vanderbilt Center for Neuroscience Drug Discovery, Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
- Department of Chemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - Kyle A. Emmitte
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, Texas 76107, United States
| | - Corey R. Hopkins
- Vanderbilt Center for Neuroscience Drug Discovery, Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - Thomas M. Bridges
- Vanderbilt Center for Neuroscience Drug Discovery, Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - Karen J. Gregory
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville VIC 3052, Australia
| | - Colleen M. Niswender
- Vanderbilt Center for Neuroscience Drug Discovery, Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
- Vanderbilt Kennedy Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - P. Jeffrey Conn
- Vanderbilt Center for Neuroscience Drug Discovery, Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
- Vanderbilt Kennedy Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
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18
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Litim N, Morissette M, Di Paolo T. Metabotropic glutamate receptors as therapeutic targets in Parkinson's disease: An update from the last 5 years of research. Neuropharmacology 2016; 115:166-179. [PMID: 27055772 DOI: 10.1016/j.neuropharm.2016.03.036] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 03/21/2016] [Accepted: 03/22/2016] [Indexed: 12/21/2022]
Abstract
Disturbance of glutamate neurotransmission in Parkinson's disease (PD) and l-DOPA induced dyskinesia (LID) is well documented. This review focuses on advances during the past five years on pharmacological modulation of metabotropic glutamate (mGlu) receptors in relation to anti-parkinsonian activity, LID attenuation, and neuroprotection. Drug design and characterization have led to the development of orthosteric agonists binding the same site as glutamate and Positive and Negative Allosteric modulators (PAMs and NAMs) binding sites different from the orthosteric site and offering subtype selectivity. Inhibition of group I (mGlu1 and mGlu5) receptors with NAMs and activation of group II (mGlu2 and 3 receptors) and group III (mGlu 4, 7 and 8 receptors) with PAMs and orthosteric agonists have shown their potential to inhibit glutamate release and attenuate excitotoxicity. Earlier and recent studies have led to the development of mGlu5 receptors NAMs to reduce LID and for neuroprotection, mGlu3 receptor agonists for neuroprotection while mGlu4 receptor PAMs and agonists for antiparkinsonian effects and neuroprotection. Furthermore, homo- and heterodimers of mGlu receptors are documented and highlight the complexity of the functioning of these receptors. Research on partial allosteric modulators and biased mGlu receptor allosteric modulators offer new glutamatergic drugs with better therapeutic effects and less off target adverse activity. Thus these various mGlu receptor targets will enable the development of novel drugs with improved clinical effects for normalization of glutamate transmission, treat PD and LID relief. This article is part of the Special Issue entitled 'Metabotropic Glutamate Receptors, 5 years on'.
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Affiliation(s)
- Nadhir Litim
- Neuroscience Research Unit, Centre Hospitalier Universitaire de Québec, CHUL, Quebec City, Canada; Faculty of Pharmacy, Laval University, Quebec City, Canada
| | - Marc Morissette
- Neuroscience Research Unit, Centre Hospitalier Universitaire de Québec, CHUL, Quebec City, Canada
| | - Thérèse Di Paolo
- Neuroscience Research Unit, Centre Hospitalier Universitaire de Québec, CHUL, Quebec City, Canada; Faculty of Pharmacy, Laval University, Quebec City, Canada.
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19
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Synthesis and evaluation of N-(methylthiophenyl)picolinamide derivatives as PET radioligands for metabotropic glutamate receptor subtype 4. Bioorg Med Chem Lett 2015; 26:133-9. [PMID: 26602273 DOI: 10.1016/j.bmcl.2015.11.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 11/03/2015] [Accepted: 11/05/2015] [Indexed: 12/19/2022]
Abstract
In recent years, mGlu4 has received great research attention because of the potential benefits of mGlu4 activation in treating numerous brain disorders, such as Parkinson's disease (PD). A specific mGlu4 PET radioligand could be an important tool in understanding the role of mGlu4 in both healthy and disease conditions, and also for the development of new drugs. In this study, we synthesized four new N-(methylthiophenyl)picolinamide derivatives 11-14. Of these ligands, 11 and 14 showed high in vitro binding affinity for mGlu4 with IC50 values of 3.4nM and 3.1nM, respectively, and suitable physicochemical parameters. Compound 11 also showed enhanced metabolic stability and good selectivity to other mGluRs. [(11)C]11 and [(11)C]14 were radiolabeled using the [(11)C]methylation of the thiophenol precursors 20a and 20c with [(11)C]CH3I in 19.0% and 34.8% radiochemical yields (RCY), and their specific activities at the end of synthesis (EOS) were 496±138GBq/μmol (n=6) and 463±263GBq/μmol (n=4), respectively. The PET studies showed that [(11)C]11 accumulated fast into the brain and had higher uptake, slower washout and 25% better contrast than [(11)C]2, indicating improved imaging characteristics as PET radiotracer for mGlu4 compared to [(11)C]2. Therefore, [(11)C]11 will be a useful radioligand to investigate mGlu4 in different biological applications.
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20
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Wild AR, Bollands M, Morris PG, Jones S. Mechanisms regulating spill-over of synaptic glutamate to extrasynaptic NMDA receptors in mouse substantia nigra dopaminergic neurons. Eur J Neurosci 2015; 42:2633-43. [PMID: 26370007 PMCID: PMC4832385 DOI: 10.1111/ejn.13075] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 08/31/2015] [Accepted: 09/08/2015] [Indexed: 02/02/2023]
Abstract
N‐Methyl‐d‐aspartate glutamate receptors (NMDARs) contribute to neural development, plasticity and survival, but they are also linked with neurodegeneration. NMDARs at synapses are activated by coincident glutamate release and depolarization. NMDARs distal to synapses can sometimes be recruited by ‘spill‐over’ of glutamate during high‐frequency synaptic stimulation or when glutamate uptake is compromised, and this influences the shape of NMDAR‐mediated postsynaptic responses. In substantia nigra dopamine neurons, activation of NMDARs beyond the synapse during different frequencies of presynaptic stimulation has not been explored, even though excitatory afferents from the subthalamic nucleus show a range of firing frequencies, and these frequencies change in human and experimental Parkinson's disease. This study reports that high‐frequency stimulation (80 Hz/200 ms) evoked NMDAR‐excitatory postsynaptic currents (EPSCs) that were larger and longer lasting than those evoked by single stimuli at low frequency (0.1 Hz). MK‐801, which irreversibly blocked NMDAR‐EPSCs activated during 0.1‐Hz stimulation, left a proportion of NMDAR‐EPSCs that could be activated by 80‐Hz stimulation and that may represent activity of NMDARs distal to synapses. TBOA, which blocks glutamate transporters, significantly increased NMDAR‐EPSCs in response to 80‐Hz stimulation, particularly when metabotropic glutamate receptors (mGluRs) were also blocked, indicating that recruitment of NMDARs distal to synapses is regulated by glutamate transporters and mGluRs. These regulatory mechanisms may be essential in the substantia nigra for restricting glutamate diffusion from synaptic sites and keeping NMDAR‐EPSCs in dopamine neurons relatively small and fast. Failure of glutamate transporters may contribute to the declining health of dopamine neurons during pathological conditions.
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Affiliation(s)
- A R Wild
- Department of Physiology, Development & Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3DY, UK
| | - M Bollands
- Department of Physiology, Development & Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3DY, UK
| | - P G Morris
- Department of Physiology, Development & Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3DY, UK
| | - S Jones
- Department of Physiology, Development & Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3DY, UK
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21
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Changes in the expression of genes encoding for mGlu4 and mGlu5 receptors and other regulators of the indirect pathway in acute mouse models of drug-induced parkinsonism. Neuropharmacology 2015; 95:50-8. [DOI: 10.1016/j.neuropharm.2015.02.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 02/19/2015] [Accepted: 02/20/2015] [Indexed: 11/23/2022]
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22
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Zhang Z, Kil KE, Poutiainen P, Choi JK, Kang HJ, Huang XP, Roth BL, Brownell AL. Re-exploring the N-phenylpicolinamide derivatives to develop mGlu4 ligands with improved affinity and in vitro microsomal stability. Bioorg Med Chem Lett 2015; 25:3956-60. [PMID: 26231155 DOI: 10.1016/j.bmcl.2015.07.031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 07/10/2015] [Accepted: 07/13/2015] [Indexed: 10/23/2022]
Abstract
In recent years, mGlu4 has received great attention and research effort because of the potential benefits of mGlu4 activation in treating numerous brain disorders, such as Parkinson's disease (PD). Many positive allosteric modulators of mGlu4 have been developed. To better understand the role of mGlu4 in healthy and disease conditions, we are interested in developing an mGlu4 selective radioligand for in vivo studies. Thus, we had synthesized and studied [(11)C]2 as a PET tracer for mGlu4, which demonstrated some promising features as a PET radioligand as well as the limitation need to be improved. In order to develop an mGlu4 ligand with enhanced affinity and improved metabolic stability, we have modified, synthesized and evaluated a series of new N-phenylpicolinamide derivatives. The SAR study has discovered a number of compounds with low nM affinity to mGlu4. The dideuteriumfluoromethoxy modified compound 24 is identified as a very promising mGlu4 ligand, which has demonstrated enhanced affinity, improved in vitro microsomal stability, good selectivity and good permeability.
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Affiliation(s)
- Zhaoda Zhang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 149, 13th Street, Suite 2301, Charlestown, MA 02129, United States
| | - Kun-Eek Kil
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 149, 13th Street, Suite 2301, Charlestown, MA 02129, United States
| | - Pekka Poutiainen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 149, 13th Street, Suite 2301, Charlestown, MA 02129, United States
| | - Ji-Kyung Choi
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 149, 13th Street, Suite 2301, Charlestown, MA 02129, United States
| | - Hye-Jin Kang
- Department of Pharmacology, University of North Carolina Chapel Hill School of Medicine, Chapel Hill, NC 27514, United States
| | - Xi-Ping Huang
- Department of Pharmacology, University of North Carolina Chapel Hill School of Medicine, Chapel Hill, NC 27514, United States
| | - Bryan L Roth
- Department of Pharmacology, University of North Carolina Chapel Hill School of Medicine, Chapel Hill, NC 27514, United States
| | - Anna-Liisa Brownell
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 149, 13th Street, Suite 2301, Charlestown, MA 02129, United States.
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23
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Gregory KJ, Conn PJ. Molecular Insights into Metabotropic Glutamate Receptor Allosteric Modulation. Mol Pharmacol 2015; 88:188-202. [PMID: 25808929 DOI: 10.1124/mol.114.097220] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 03/24/2015] [Indexed: 12/21/2022] Open
Abstract
The metabotropic glutamate (mGlu) receptors are a group of eight family C G protein-coupled receptors that are expressed throughout the central nervous system (CNS) and periphery. Within the CNS the different subtypes are found in neurons, both pre- and/or postsynaptically, where they mediate modulatory roles and in glial cells. The mGlu receptor family provides attractive targets for numerous psychiatric and neurologic disorders, with the majority of discovery programs focused on targeting allosteric sites, with allosteric ligands now available for all mGlu receptor subtypes. However, the development of allosteric ligands remains challenging. Biased modulation, probe dependence, and molecular switches all contribute to the complex molecular pharmacology exhibited by mGlu receptor allosteric ligands. In recent years we have made significant progress in our understanding of this molecular complexity coupled with an increased understanding of the structural basis of mGlu allosteric modulation.
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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 Vanderbilt Center for Neuroscience Drug Discovery & Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (P.J.C)
| | - P Jeffrey Conn
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (K.J.G.); and Vanderbilt Center for Neuroscience Drug Discovery & Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (P.J.C)
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24
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Opportunities and challenges in the discovery of allosteric modulators of GPCRs for treating CNS disorders. Nat Rev Drug Discov 2014; 13:692-708. [PMID: 25176435 DOI: 10.1038/nrd4308] [Citation(s) in RCA: 203] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Novel allosteric modulators of G protein-coupled receptors (GPCRs) are providing fundamental advances in the development of GPCR ligands with high subtype selectivity and novel modes of efficacy that have not been possible with traditional approaches. As new allosteric modulators are advancing as drug candidates, we are developing an increased understanding of the major advantages and broad range of activities that can be achieved with these agents through selective modulation of specific signalling pathways, differential effects on GPCR homodimers versus heterodimers, and other properties. This understanding creates exciting opportunities, as well as unique challenges, in the optimization of novel therapeutic agents for disorders of the central nervous system.
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25
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Kil KE, Poutiainen P, Zhang Z, Zhu A, Choi JK, Jokivarsi K, Brownell AL. Radiosynthesis and evaluation of an 18F-labeled positron emission tomography (PET) radioligand for metabotropic glutamate receptor subtype 4 (mGlu4). J Med Chem 2014; 57:9130-8. [PMID: 25330258 PMCID: PMC4230996 DOI: 10.1021/jm501245b] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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Four 4-phthalimide derivatives of N-(3-chlorophenyl)-2-picolinamide
were synthesized as potential ligands for the PET imaging of mGlu4 in the brain. Of these compounds, N-(3-chloro-4-(4-fluoro-1,3-dioxoisoindolin-2-yl)phenyl)-2-picolinamide
(3, KALB001) exhibited improved binding affinity (IC50 = 5.1 nM) compared with ML128 (1) and was subsequently
labeled with 18F. When finally formulated in 0.1 M citrate
buffer (pH 4) with 10% ethanol, the specific activity of [18F]3 at the end of synthesis (EOS) was 233.5 ± 177.8
GBq/μmol (n = 4). The radiochemical yield of
[18F]3 was 16.4 ± 4.8% (n = 4), and the purity was over 98%. In vivo imaging studies in a
monkey showed that the radiotracer quickly penetrated
the brain with the highest accumulation in the brain areas known to
express mGlu4. Despite some unfavorable radiotracer properties
like fast washout in rodent studies, [18F]3 is the first 18F-labeled mGlu4 radioligand,
which can be further modified to improve pharmacokinetics and brain
penetrability for future human studies.
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Affiliation(s)
- Kun-Eek Kil
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital , Charlestown, Massachusetts 02129, United States
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26
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Mercier MS, Lodge D. Group III metabotropic glutamate receptors: pharmacology, physiology and therapeutic potential. Neurochem Res 2014; 39:1876-94. [PMID: 25146900 DOI: 10.1007/s11064-014-1415-y] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 08/08/2014] [Accepted: 08/11/2014] [Indexed: 01/14/2023]
Abstract
Glutamate, the primary excitatory neurotransmitter in the central nervous system (CNS), exerts neuromodulatory actions via the activation of metabotropic glutamate (mGlu) receptors. There are eight known mGlu receptor subtypes (mGlu1-8), which are widely expressed throughout the brain, and are divided into three groups (I-III), based on signalling pathways and pharmacological profiles. Group III mGlu receptors (mGlu4/6/7/8) are primarily, although not exclusively, localised on presynaptic terminals, where they act as both auto- and hetero-receptors, inhibiting the release of neurotransmitter. Until recently, our understanding of the role of individual group III mGlu receptor subtypes was hindered by a lack of subtype-selective pharmacological tools. Recent advances in the development of both orthosteric and allosteric group III-targeting compounds, however, have prompted detailed investigations into the possible functional role of these receptors within the CNS, and revealed their involvement in a number of pathological conditions, such as epilepsy, anxiety and Parkinson's disease. The heterogeneous expression of group III mGlu receptor subtypes throughout the brain, as well as their distinct distribution at glutamatergic and GABAergic synapses, makes them ideal targets for therapeutic intervention. This review summarises the advances in subtype-selective pharmacology, and discusses the individual roles of group III mGlu receptors in physiology, and their potential involvement in disease.
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Affiliation(s)
- Marion S Mercier
- Centre for Synaptic Plasticity, School of Physiology and Pharmacology, Dorothy Hodgkin Building, University of Bristol, Bristol, BS1 3NY, UK,
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27
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Selective actions of novel allosteric modulators reveal functional heteromers of metabotropic glutamate receptors in the CNS. J Neurosci 2014; 34:79-94. [PMID: 24381270 DOI: 10.1523/jneurosci.1129-13.2014] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Metabotropic glutamate (mGlu) receptors play important roles in regulating CNS function and are known to function as obligatory dimers. Although recent studies have suggested heterodimeric assembly of mGlu receptors in vitro, the demonstration that distinct mGlu receptor proteins can form heterodimers or hetero-complexes with other mGlu subunits in native tissues, such as neurons, has not been shown. Using biochemical and pharmacological approaches, we demonstrate here that mGlu2 and mGlu4 form a hetero-complex in native rat and mouse tissues which exhibits a distinct pharmacological profile. These data greatly extend our current understanding of mGlu receptor interaction and function and provide compelling evidence that mGlu receptors can function as heteromers in intact brain circuits.
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28
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Nickols HH, Conn PJ. Development of allosteric modulators of GPCRs for treatment of CNS disorders. Neurobiol Dis 2014; 61:55-71. [PMID: 24076101 PMCID: PMC3875303 DOI: 10.1016/j.nbd.2013.09.013] [Citation(s) in RCA: 163] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 09/13/2013] [Accepted: 09/17/2013] [Indexed: 12/14/2022] Open
Abstract
The discovery of allosteric modulators of G protein-coupled receptors (GPCRs) provides a promising new strategy with potential for developing novel treatments for a variety of central nervous system (CNS) disorders. Traditional drug discovery efforts targeting GPCRs have focused on developing ligands for orthosteric sites which bind endogenous ligands. Allosteric modulators target a site separate from the orthosteric site to modulate receptor function. These allosteric agents can either potentiate (positive allosteric modulator, PAM) or inhibit (negative allosteric modulator, NAM) the receptor response and often provide much greater subtype selectivity than orthosteric ligands for the same receptors. Experimental evidence has revealed more nuanced pharmacological modes of action of allosteric modulators, with some PAMs showing allosteric agonism in combination with positive allosteric modulation in response to endogenous ligand (ago-potentiators) as well as "bitopic" ligands that interact with both the allosteric and orthosteric sites. Drugs targeting the allosteric site allow for increased drug selectivity and potentially decreased adverse side effects. Promising evidence has demonstrated potential utility of a number of allosteric modulators of GPCRs in multiple CNS disorders, including neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and Huntington's disease, as well as psychiatric or neurobehavioral diseases such as anxiety, schizophrenia, and addiction.
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Key Words
- (+)-6-(2,4-dimethylphenyl)-2-ethyl-6,7-dihydrobenzo[d]oxazol-4(5H)-one
- (1-(4-cyano-4-(pyridine-2-yl)piperidine-1-yl)methyl-4-oxo-4H-quinolizine-3-carboxylic acid)
- (1S,2S)-N(1)-(3,4-dichlorophenyl)cyclohexane-1,2-dicarboxamide
- (1S,3R,4S)-1-aminocyclo-pentane-1,3,4-tricarboxylic acid
- (3,4-dihydro-2H-pyrano[2,3]b quinolin-7-yl)(cis-4-methoxycyclohexyl) methanone
- (3aS,5S,7aR)-methyl 5-hydroxy-5-(m-tolylethynyl)octahydro-1H-indole-1-carboxylate
- 1-(1′-(2-methylbenzyl)-1,4′-bipiperidin-4-yl)-1H-benzo[d]imidazol-2(3H)-one
- 1-[3-(4-butyl-1-piperidinyl)propyl]-3,4-dihydro-2(1H)-quinolinone
- 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine
- 2-(2-(3-methoxyphenyl)ethynyl)-5-methylpyridine
- 2-chloro-4-((2,5-dimethyl-1-(4-(trifluoromethoxy)phenyl)-1Himidazol-4-yl)ethynyl)pyridine
- 2-methyl-6-(2-phenylethenyl)pyridine
- 2-methyl-6-(phenylethynyl)-pyridine
- 3-cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl)benzamide
- 3-cyclohexyl-5-fluoro-6-methyl-7-(2-morpholin-4-ylethoxy)-4H-chromen-4-one
- 3[(2-methyl-1,3-thiazol-4-yl)ethylnyl]pyridine
- 4-((E)-styryl)-pyrimidin-2-ylamine
- 4-[1-(2-fluoropyridin-3-yl)-5-methyl-1H-1,2,3-triazol-4-yl]-N-isopropyl-N-methyl-3,6-dihydropyridine-1(2H)-carboxamide
- 4-n-butyl-1-[4-(2-methylphenyl)-4-oxo-1-butyl]-piperidine
- 5-methyl-6-(phenylethynyl)-pyridine
- 5MPEP
- 6-(4-methoxyphenyl)-5-methyl-3-(4-pyridinyl)-isoxazolo[4,5-c]pyridin-4(5H)-one
- 6-OHDA
- 6-hydroxydopamine
- 6-methyl-2-(phenylazo)-3-pyridinol
- 77-LH-28-1
- 7TMR
- AC-42
- ACPT-1
- AChE
- AD
- ADX71743
- AFQ056
- APP
- Allosteric modulator
- Alzheimer's disease
- BINA
- BQCA
- CDPPB
- CFMMC
- CNS
- CPPHA
- CTEP
- DA
- DFB
- DHPG
- Drug discovery
- ERK1/2
- FMRP
- FTIDC
- FXS
- Fragile X syndrome
- GABA
- GPCR
- JNJ16259685
- L-AP4
- L-DOPA
- Lu AF21934
- Lu AF32615
- M-5MPEP
- MMPIP
- MPEP
- MPTP
- MTEP
- Metabotropic glutamate receptor
- Muscarinic acetylcholine receptor
- N-[4-chloro-2[(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)methyl]phenyl]-2-hydrobenzamide
- N-methyl-d-aspartate
- N-phenyl-7-(hydroxylimino)cyclopropa[b]chromen-1a-carboxamide
- NAM
- NMDA
- PAM
- PCP
- PD
- PD-LID
- PET
- PHCCC
- PQCA
- Parkinson's disease
- Parkinson's disease levodopa-induced dyskinesia
- SAM
- SIB-1757
- SIB-1893
- TBPB
- [(3-fluorophenyl)methylene]hydrazone-3-fluorobenzaldehyde
- acetylcholinesterase
- amyloid precursor protein
- benzylquinolone carboxylic acid
- central nervous system
- dihydroxyphenylglycine
- dopamine
- extracellular signal-regulated kinase 1/2
- fragile X mental retardation protein
- l-(+)-2-amino-4-phosphonobutyric acid
- l-3,4-dihydroxyphenylalanine
- mGlu
- metabotropic glutamate receptor
- negative allosteric modulator
- phencyclidine
- positive allosteric modulator
- positron emission tomography
- potassium 30-([(2-cyclopentyl-6-7-dimethyl-1-oxo-2,3-dihydro-1H-inden-5yl)oxy]methyl)biphenyl l-4-carboxylate
- seven transmembrane receptor
- silent allosteric modulator
- γ-aminobutyric acid
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Affiliation(s)
- Hilary Highfield Nickols
- Division of Neuropathology, Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN, 37232, USA
| | - P. Jeffrey Conn
- Department of Pharmacology, Vanderbilt University, Nashville, TN, 37232, USA
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29
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Williams CJ, Dexter DT. Neuroprotective and symptomatic effects of targeting group III mGlu receptors in neurodegenerative disease. J Neurochem 2013; 129:4-20. [PMID: 24224472 DOI: 10.1111/jnc.12608] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Revised: 10/28/2013] [Accepted: 11/06/2013] [Indexed: 12/21/2022]
Abstract
Neurodegenerative disorders possess common pathological mechanisms, such as protein aggregation, inflammation, oxidative stress (OS) and excitotoxicity, raising the possibility of shared therapeutic targets. As a result of the selective cellular and regional expression of group III metabotropic glutamate (mGlu) receptors, drugs targeting such receptors have demonstrated both neuroprotective properties and symptomatic improvements in several models of neurodegeneration. In recent years, the discovery and development of subtype-selective ligands for the group III mGlu receptors has gained pace, allowing further research into the functions of these receptors and revealing their roles in health and disease. Activation of this class of receptors results in neuroprotection, with a variety of underlying mechanisms implicated. Group III mGlu receptor stimulation prevents excitotoxicity by inhibiting glutamate release from neurons and microglia and increasing glutamate uptake by astrocytes. It also attenuates the neuroinflammatory response by reducing glial reactivity and encourages neurotrophic phenotypes. This article will review the current literature with regard to the neuroprotective and symptomatic effects of group III mGlu receptor activation and discuss their promise as therapeutic targets in neurodegenerative disease. We review the neuroprotective and symptomatic effects of targeting group III mGlu receptors in neurodegenerative disease: Excess extracellular glutamate causes overactivation of NMDA receptors resulting in excitotoxicity. Externalization of phosphatidylserine stimulates phagocytosis of neurons by activated microglia, which contribute to damage through glutamate and pro-inflammatory factor release. Reactive astrocytes produce cytotoxic factors enhancing neuronal cell death. Activation of group III mGlu receptors by glutamate and/or mGlu receptor ligands results in inhibition of glutamate release from presynaptic terminals and microglia, reducing excitotoxicity. Astrocytic glutamate uptake is increased and microglia produce neurotrophic factors.
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Affiliation(s)
- Claire J Williams
- Parkinson's Disease Research Group, Centre for Neuroinflammation and Neurodegeneration, Division of Brain Sciences, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, London, UK
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30
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Betts MJ, O'Neill MJ, Duty S. Allosteric modulation of the group III mGlu4 receptor provides functional neuroprotection in the 6-hydroxydopamine rat model of Parkinson's disease. Br J Pharmacol 2012; 166:2317-30. [PMID: 22404342 DOI: 10.1111/j.1476-5381.2012.01943.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND AND PURPOSE We recently reported that broad spectrum agonist-induced activation of presynaptic group III metabotropic glutamate (mGlu) receptors within the substantia nigra pars compacta using L-2-amino-4-phosphonobutyrate provided functional neuroprotection in the 6-hydroxydopamine lesion rat model of Parkinson's disease. The aim of this study was to establish whether selective activation of the mGlu(4) receptor alone could afford similar functional neuroprotection. EXPERIMENTAL APPROACH The neuroprotective effects of 8 days of supranigral treatment with a positive allosteric modulator of mGlu(4) receptors, (+/-)-cis-2-(3,5-dichlorphenylcarbamoyl)cyclohexanecarboxylic acid (VU0155041), were investigated in rats with unilateral 6-hydroxydopamine lesions. The effects of VU0155041 treatment on motor function were assessed using both habitual (cylinder test) and forced (adjusted stepping, amphetamine-induced rotations) behavioural tests. Nigrostriatal tract integrity was examined by analysis of tyrosine hydroxylase, dopa decarboxylase or dopamine levels in the striatum and tyrosine hydroxylase-positive cell counts in the substantia nigra pars compacta. KEY RESULTS VU0155041 provided around 40% histological protection against a unilateral 6-hydroxydopamine lesion as well as significant preservation of motor function. These effects were inhibited by pre-treatment with (RS)-α-cyclopropyl-4-phosphonophenylglycine, confirming a receptor-mediated response. Reduced levels of inflammatory markers were also evident in the brains of VU0155041-treated animals. CONCLUSIONS AND IMPLICATIONS Allosteric potentiation of mGlu(4) receptors in the substantia nigra pars compacta provided neuroprotective effects in the 6-hydroxydopamine rat model A reduced inflammatory response may contribute, in part, to this action. In addition to the reported symptomatic effects, activation of mGlu(4) receptors may also offer a novel approach for slowing the progressive degeneration observed in Parkinson's disease.
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Affiliation(s)
- Matthew J Betts
- King's College London, Wolfson Centre for Age-Related Diseases, Guy's Campus, London, UK
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31
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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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32
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Le Poul E, Boléa C, Girard F, Poli S, Charvin D, Campo B, Bortoli J, Bessif A, Luo B, Koser AJ, Hodge LM, Smith KM, DiLella AG, Liverton N, Hess F, Browne SE, Reynolds IJ. A potent and selective metabotropic glutamate receptor 4 positive allosteric modulator improves movement in rodent models of Parkinson's disease. J Pharmacol Exp Ther 2012; 343:167-77. [PMID: 22787118 DOI: 10.1124/jpet.112.196063] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Positive allosteric modulators (PAMs) of metabotropic glutamate receptor 4 (mGluR4) have been proposed as a novel therapeutic approach for the treatment of Parkinson's disease. However, evaluation of this proposal has been limited by the availability of appropriate pharmacological tools to interrogate the target. In this study, we describe the properties of a novel mGluR4 PAM. 5-Methyl-N-(4-methylpyrimidin-2-yl)-4-(1H-pyrazol-4-yl)thiazol-2-amine (ADX88178) enhances glutamate-mediated activation of human and rat mGluR4 with EC(50) values of 4 and 9 nM, respectively. The compound is highly selective for mGluR4 with minimal activities at other mGluRs. Oral administration of ADX88178 in rats is associated with high bioavailability and results in cerebrospinal fluid exposure of >50-fold the in vitro EC(50) value. ADX88178 reverses haloperidol-induced catalepsy in rats at 3 and 10 mg/kg. It is noteworthy that this compound alone has no impact on forelimb akinesia resulting from a bilateral 6-hydroxydopamine lesion in rats. However, coadministration of a low dose of L-DOPA (6 mg/kg) enabled a robust, dose-dependent reversal of the forelimb akinesia deficit. ADX88178 also increased the effects of quinpirole in lesioned rats and enhanced the effects of L-DOPA in MitoPark mice. It is noteworthy that the enhancement of the actions of L-DOPA was not associated with an exacerbation of L-DOPA-induced dyskinesias in rats. ADX88178 is a novel, potent, and selective mGluR4 PAM that is a valuable tool for exploring the therapeutic potential of mGluR4 modulation. The use of this novel tool molecule supports the proposal that activation of mGluR4 may be therapeutically useful in Parkinson's disease.
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Amalric M, Lopez S, Goudet C, Fisone G, Battaglia G, Nicoletti F, Pin JP, Acher FC. Group III and subtype 4 metabotropic glutamate receptor agonists: discovery and pathophysiological applications in Parkinson's disease. Neuropharmacology 2012; 66:53-64. [PMID: 22664304 DOI: 10.1016/j.neuropharm.2012.05.026] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 04/28/2012] [Accepted: 05/21/2012] [Indexed: 12/22/2022]
Abstract
Restoring the balance between excitatory and inhibitory circuits in the basal ganglia, following the loss of dopaminergic (DA) neurons of the substantia nigra pars compacta, represents a major challenge to treat patients affected by Parkinson's disease (PD). The imbalanced situation in favor of excitation in the disease state may also accelerate excitotoxic processes, thereby representing a potential target for neuroprotective therapies. Reducing the excitatory action of glutamate, the major excitatory neurotransmitter in the basal ganglia, should lead to symptomatic improvement for PD patients and may promote the survival of DA neurons. Recent studies have focused on the modulatory action of metabotropic glutamate (mGlu) receptors on neurodegenerative diseases including PD. Group III mGlu receptors, including subtypes 4, 7 and 8, are largely expressed in the basal ganglia. Recent studies highlight the use of selective mGlu4 receptor positive allosteric modulators (PAMs) for the treatment of PD. Here we review the effects of newly-designed group-III orthosteric agonists on neuroprotection, neurorestoration and reduction of l-DOPA induced dyskinesia in animal models of PD. The combination of orthosteric mGlu4 receptor selective agonists with PAMs may open new avenues for the symptomatic treatment of PD. This article is part of a Special Issue entitled 'Metabotropic Glutamate Receptors'.
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Affiliation(s)
- M Amalric
- Aix-Marseille University, CNRS UMR 7291, Laboratoire de Neurosciences Fonctionnelles, Case C, 3 Place Victor Hugo, 13331 Marseille Cedex 3, France.
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Broadstock M, Austin PJ, Betts MJ, Duty S. Antiparkinsonian potential of targeting group III metabotropic glutamate receptor subtypes in the rodent substantia nigra pars reticulata. Br J Pharmacol 2012; 165:1034-45. [PMID: 21627638 DOI: 10.1111/j.1476-5381.2011.01515.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND AND PURPOSE Increased firing of the glutamatergic pathway between the subthalamic nucleus and substantia nigra pars reticulata (SNpr) contributes to the abnormal firing of motor circuits and subsequent motor deficits seen in Parkinson's disease. Broad spectrum agonist-induced activation of presynaptic group III metabotropic glutamate (mGlu) receptors within the SNpr reduced glutamate release and reversed akinesia in the reserpine-treated rat model of Parkinson's disease. Here, we have sought to identify which subtypes of group III mGlu receptor in the SNpr were responsible for these beneficial effects. EXPERIMENTAL APPROACH The ability of the mGlu(4) positive allosteric modulator, N-phenyl-7-(hydroxyminocyclopropa[b]chromen-1a-carboxamide) (PHCCC), the mGlu(7) allosteric agonist, N,N'-dibenzhydrylethane-1,2-diamine dihydrochloride (AMN082) and the mGlu(8) -selective agonist (S)-3,4-dicarboxyphenylglycine [(S)-3,4-DCPG] to inhibit KCl-evoked [(3) H]-D-aspartate release was examined in vitro in rat nigral prisms. Reversal of akinesia in reserpine-treated rats was also assessed following intranigral injection of these agents. KEY RESULTS PHCCC and AMN082 inhibited [(3) H]-D-aspartate release by 42% and 53%, respectively when given alongside a sub-threshold concentration of the broad spectrum group III agonist, L-2-amino-4-phosphonobutyrate (L-AP4; 1 µM). In contrast (S)-3,4-DCPG failed to inhibit [(3) H]-D-aspartate release. All three agents also reversed reserpine-induced akinesia although only the effects of PHCCC and AMN082 were inhibited by pre-treatment with the group III antagonist (RS)-α-cyclopropyl-4-phosphonophenylglycine (CPPG). CONCLUSIONS AND IMPLICATIONS These findings reveal that targeting SNpr mGlu(4) or mGlu(7) receptors, but not mGlu(8) receptors, provided relief from akinesia in the reserpine-treated rat model of Parkinson's disease, most likely reflecting inhibition of excess glutamate release in this region.
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Affiliation(s)
- M Broadstock
- King's College London, Wolfson Centre for Age-Related Diseases, Guy's Campus, London, UK
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Bennouar KE, Uberti MA, Melon C, Bacolod MD, Jimenez HN, Cajina M, Kerkerian-Le Goff L, Doller D, Gubellini P. Synergy between L-DOPA and a novel positive allosteric modulator of metabotropic glutamate receptor 4: implications for Parkinson's disease treatment and dyskinesia. Neuropharmacology 2012; 66:158-69. [PMID: 22491024 DOI: 10.1016/j.neuropharm.2012.03.022] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 02/27/2012] [Accepted: 03/24/2012] [Indexed: 11/29/2022]
Abstract
Group III metabotropic glutamate (mGlu) receptors are localized in presynaptic terminals within basal ganglia (BG) circuitry that become hyperactive due to dopamine depletion in Parkinson's disease (PD). For this reason, group III mGlu receptors, in particular mGlu4, have been considered as key strategic targets for non-dopaminergic pharmacological treatments aimed at modulating these synapses, without producing the well known side-effects of l-DOPA, in particular the highly disabling l-DOPA-induced dyskinesia (LID). Herein we add physiological and functional support to this hypothesis using Lu AF21934, a novel selective and brain-penetrant mGlu4 receptor positive allosteric modulator (PAM) tool compound. By in vitro electrophysiological recordings we demonstrate that Lu AF21934 inhibits corticostriatal synaptic transmission and enhances the effect of the orthosteric mGlu4 receptor-preferred agonist LSP1-2111. In naïve rats, Lu AF21934 dose-dependently (10 and 30 mg/kg) alleviated haloperidol-induced catalepsy. In hemiparkinsonian rats (unilateral 6-hydroxydopamine lesion of the substantia nigra pars compacta), Lu AF21934 alone did not affect akinesia at the doses tested (10 and 30 mg/kg). However, when Lu AF21934 was combined with sub-threshold doses of l-DOPA (1 and 5 mg/kg), it acted synergistically in alleviating akinesia in a dose-dependent manner and, notably, also reduced the incidence of LID but not its severity. Interestingly, these effects occurred at Lu AF21934 brain free concentrations that showed functional activity in in vitro screens (calcium flux and electrophysiology assays). These results support the potential for antiparkinsonian clinical use of a combined treatment consisting in l-DOPA and a mGlu4 receptor PAM to reduce efficacious l-DOPA doses (generally known as l-DOPA sparing), while maintaining the same benefit on PD motor troubles, and at the same time minimizing the development of LID. This article is part of a Special Issue entitled 'Metabotropic Glutamate Receptors'.
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Affiliation(s)
- Khaled-Ezaheir Bennouar
- Aix-Marseille Univ, Institut de Biologie du Développement de Marseille-Luminy (IBDML), UMR 7288, 13009 Marseille, France
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Célanire S, Campo B. Recent advances in the drug discovery of metabotropic glutamate receptor 4 (mGluR4) activators for the treatment of CNS and non-CNS disorders. Expert Opin Drug Discov 2012; 7:261-80. [PMID: 22468956 DOI: 10.1517/17460441.2012.660914] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION The metabotropic glutamate receptor type 4 (mGluR4) plays a pivotal role in a plethora of therapeutic areas, as recently demonstrated in preclinical validation studies with several chemical classes of compounds in rodent models of central nervous system (CNS) and peripheral disorders. Activation of mGluR4 with orthosteric agonists, allosteric agonists or pure positive allosteric modulators (PAM) has been postulated to be of broad therapeutic use. AREAS COVERED The authors address past and current drug discovery efforts, insights and achievements in the field toward the identification of therapeutically promising and emerging class of mGluR4 activators, over the 2005 - 2011 period. Chemical structures, properties and in vivo pharmacological results discussed in the present review were retrieved from public literature including PubMed searches, Thomson Pharma and SciFinder databases searches, conferences, proceedings and posters. EXPERT OPINION Developing a subtype-selective, orally bioavailable brain penetrant mGluR4 orthosteric agonist remains challenging. Lack of subtype selectivity and low brain penetration has been a common limitation of the first generation of mGluR4 agonist and potentiators. However, significant progress has recently been made with the identification of several double- to single-digit nanomolar mGluR4 PAM having reasonable pharmacokinetic properties, oral bioavailability and brain penetration. The use of such compounds in research has led to advancement in understanding the central role of mGluR4 in multiple neurodegenerative and neuroinflammatory disorders, such as Parkinson's disease and multiple sclerosis. Our understanding of the potential application of mGluR4 as therapeutic target is expected to grow as these compounds advance into preclinical and clinical development.
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Affiliation(s)
- Sylvain Célanire
- Medicinal Chemistry Department, Addex Pharmaceuticals, Geneva, Switzerland.
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Davis MJ, Haley T, Duvoisin RM, Raber J. Measures of anxiety, sensorimotor function, and memory in male and female mGluR4⁻/⁻ mice. Behav Brain Res 2012; 229:21-8. [PMID: 22227508 DOI: 10.1016/j.bbr.2011.12.037] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 12/21/2011] [Accepted: 12/22/2011] [Indexed: 11/15/2022]
Abstract
Metabotropic glutamate receptors (mGluRs) are coupled to second messenger pathways via G proteins and modulate synaptic transmission. Of the eight different types of mGluRs (mGluR1-mGluR8), mGluR4, mGluR6, mGluR7, and mGluR8 are members of group III. Group III receptors are generally located presynaptically, where they regulate neurotransmitter release. Because of their role in modulating neurotransmission, mGluRs are attractive targets for therapies aimed at treating anxiety disorders. Previously we showed that the mGluR4-selective allosteric agonist VU 0155041 reduces anxiety-like behavior in wild-type male mice. Here, we explore the role of mGluR4 in adult (6-month old) and middle-aged (12-month old) male and female mice lacking this receptor. Compared to age- and sex-matched wild-type mice, middle-aged mGluR4(-/-) male mice showed increased measures of anxiety in the open field and elevated zero maze and impaired sensorimotor function on the rotarod. These changes were not seen in adult 6-month-old male mice. In contrast to the male mice, mGluR4(-/-) female mice showed reduced measures of anxiety in the open field and elevated zero maze and enhanced rotarod performance. During the hidden platform training sessions of the water maze, mGluR4(-/-) mice swam farther away from the platform than wild-type mice at 6, but not at 12, months of age. mGluR4(-/-) mice also showed enhanced amygdala-dependent cued fear conditioning. No genotype differences were seen in hippocampus-dependent contextual fear conditioning. These data indicate that effects of mGluR4 on sensorimotor function and measures of anxiety, but not cued fear conditioning, are critically modulated by sex and age.
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Affiliation(s)
- Matthew J Davis
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR 97239, USA
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Metabotropic Glutamate Receptor–Dopamine Interactions in the Basal Ganglia Motor Circuit. ACTA ACUST UNITED AC 2011. [DOI: 10.1201/b11284-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Jones CK, Bubser M, Thompson AD, Dickerson JW, Turle-Lorenzo N, Amalric M, Blobaum AL, Bridges TM, Morrison RD, Jadhav S, Engers DW, Italiano K, Bode J, Daniels JS, Lindsley CW, Hopkins CR, Conn PJ, Niswender CM. The metabotropic glutamate receptor 4-positive allosteric modulator VU0364770 produces efficacy alone and in combination with L-DOPA or an adenosine 2A antagonist in preclinical rodent models of Parkinson's disease. J Pharmacol Exp Ther 2011; 340:404-21. [PMID: 22088953 DOI: 10.1124/jpet.111.187443] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Parkinson's disease (PD) is a debilitating neurodegenerative disorder associated with severe motor impairments caused by the loss of dopaminergic innervation of the striatum. Previous studies have demonstrated that positive allosteric modulators (PAMs) of metabotropic glutamate receptor 4 (mGlu₄), including N-phenyl-7-(hydroxyimino) cyclopropa[b]chromen-1a-carboxamide, can produce antiparkinsonian-like effects in preclinical models of PD. However, these early mGlu₄ PAMsexhibited unsuitable physiochemical properties for systemic dosing, requiring intracerebroventricular administration and limiting their broader utility as in vivo tools to further understand the role of mGlu₄ in the modulation of basal ganglia function relevant to PD. In the present study, we describe the pharmacologic characterization of a systemically active mGlu₄ PAM, N-(3-chlorophenyl)picolinamide (VU0364770), in several rodent PD models. VU0364770 showed efficacy alone or when administered in combination with L-DOPA or an adenosine 2A (A2A) receptor antagonist currently in clinical development (preladenant). When administered alone, VU0364770 exhibited efficacy in reversing haloperidol-induced catalepsy, forelimb asymmetry-induced by unilateral 6-hydroxydopamine (6-OHDA) lesions of the median forebrain bundle, and attentional deficits induced by bilateral 6-OHDA nigrostriatal lesions in rats. In addition, VU0364770 enhanced the efficacy of preladenant to reverse haloperidol-induced catalepsy when given in combination. The effects of VU0364770 to reverse forelimb asymmetry were also potentiated when the compound was coadministered with an inactive dose of L-DOPA, suggesting that mGlu₄ PAMs may provide L-DOPA-sparing activity. The present findings provide exciting support for the potential role of selective mGlu₄ PAMs as a novel approach for the symptomatic treatment of PD and a possible augmentation strategy with either L-DOPA or A2A antagonists.
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Affiliation(s)
- Carrie K Jones
- Vanderbilt Center for Neuroscience Drug Discovery, Department of Pharmacology, Vanderbilt University, Nashville, TN 37212, USA
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mGluR4-positive allosteric modulation as potential treatment for Parkinson's disease. Future Med Chem 2011; 1:501-13. [PMID: 20161443 DOI: 10.4155/fmc.09.38] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Although Parkinson's disease was first diagnosed nearly 200 years ago, its effective treatment still remains elusive for most of those diagnosed. The gold standard of treatment for most patients is 3,4-dihydroxy-L-phenylalanine. This drug works for most individuals early in the disease; however, resistant symptoms start to emerge after several years of treatment. There has been increased interest in finding novel therapies to help Parkinson's disease patients. Such strategies may have the benefit of not only treating the symptomatic issues of the disorder, but might also offer promise in protecting dopaminergic neurons from further degeneration. One such target that is now receiving much attention from the scientific community is the metabotropic glutamate receptor mGluR4. In this article, we briefly review Parkinson's disease and then recent work in the mGluR area, with a focus on the efforts being made toward finding and optimizing novel mGluR4 positive allosteric modulators (PAMs). Preclinically in rodent models, mGluR4 activation has offered much promise as a novel treatment of Parkinson's disease. Additionally, the specific use of PAMs, rather than direct-acting agonists at the orthosteric glutamate site, continues to be validated as a viable treatment option for this target. It is anticipated that continued progress in this area will further our understanding of the potential of mGluR4 modulation as a novel symptomatic and potentially disease-modifying treatment for Parkinson's disease.
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Gosnell HB, Silberman Y, Grueter BA, Duvoisin RM, Raber J, Winder DG. mGluR8 modulates excitatory transmission in the bed nucleus of the stria terminalis in a stress-dependent manner. Neuropsychopharmacology 2011; 36:1599-607. [PMID: 21451497 PMCID: PMC3138653 DOI: 10.1038/npp.2011.40] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Metabotropic glutamate receptors (mGluRs) are important modulators of excitatory transmission, and have been implicated in anxiety and stress-related behaviors. Previously, we showed that group III mGluR agonists could depress excitatory synaptic transmission in the bed nucleus of the stria terminalis (BNST), an integral component of the anxiety circuitry. Here, we provide converging evidence indicating that this effect is mediated primarily by mGluR8, is exerted presynaptically, and is modulated by noradrenergic signaling and stress. The effects of the group III mGluR agonist L-AP4 on excitatory transmission are not potentiated by the mGluR4-selective allosteric potentiator PHCCC, but are mimicked by the mGluR8-selective agonist DCPG. Consistent with these results, mGluR8-like immunoreactivity is seen in the BNST, and the actions of L-AP4 on excitatory transmission are absent in slices from mGluR8 knockout (KO) mice. Application of DCPG is associated with an increase in paired-pulse evoked glutamate synaptic currents, and a decrease in spontaneous glutamate synaptic current frequency, consistent with a primarily presynaptic action. mGluR8-mediated suppression of excitatory transmission is disrupted ex vivo by activation of α1 adrenergic receptors (α1 ARs). BNST mGluR8 function is also disrupted by both acute and chronic in vivo exposure to restraint stress, and in brain slices from α2A AR KO mice. These studies show that mGluR8 is an important regulator of excitatory transmission in the BNST, and suggest that this receptor is selectively disrupted by noradrenergic signaling and by both acute and chronic stress.
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Affiliation(s)
- Heather B Gosnell
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA,Kennedy Center for Research on Human Development, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Yuval Silberman
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Brad A Grueter
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Robert M Duvoisin
- Departments of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR, USA
| | - Jacob Raber
- Division of Neuroscience, Departments of Behavioral Neuroscience, and Neurology, ONPRC, Oregon Health & Science University, Portland, OR, USA
| | - Danny G Winder
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA,Kennedy Center for Research on Human Development, Vanderbilt University School of Medicine, Nashville, TN, USA,Center for Molecular Neuroscience, Vanderbilt University School of Medicine, Nashville, TN, USA,Department of Molecular Physiology and Biophysics, Vanderbilt University, School of Medicine, Nashville, TN 37232, USA. Tel: +1 615 322 1144; Fax: +1 615 322 1462; E-mail:
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Duty S. Therapeutic potential of targeting group III metabotropic glutamate receptors in the treatment of Parkinson's disease. Br J Pharmacol 2011; 161:271-87. [PMID: 20735415 PMCID: PMC2989582 DOI: 10.1111/j.1476-5381.2010.00882.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Current drugs used in the treatment of Parkinson's disease (PD), for example, L-DOPA and dopamine agonists, are very effective at reversing the motor symptoms of the disease. However, they do little to combat the underlying degeneration of dopaminergic neurones in the substantia nigra pars compacta (SNc) and their long-term use is associated with the appearance of adverse effects such as L-DOPA-induced dyskinesia. Much emphasis has therefore been placed on finding alternative non-dopaminergic drugs that may circumvent some or all of these problems. Group III metabotropic glutamate (mGlu) receptors were first identified in the basal ganglia a decade ago. One or more of these receptors (mGlu4, mGlu7 or mGlu8) is found on pre-synaptic terminals of basal ganglia pathways whose overactivity is implicated not only in the generation of motor symptoms in PD, but also in driving the progressive SNc degeneration. The finding that drugs which activate group III mGlu receptors can inhibit transmission across these overactive synapses has lead to the proposal that group III mGlu receptors are promising targets for drug discovery in PD. This paper provides a comprehensive review of the role and target potential of group III mGlu receptors in the basal ganglia. Overwhelming evidence obtained from in vitro studies and animal models of PD supports group III mGlu receptors as potentially important drug targets for providing both symptom relief and neuroprotection in PD.
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Affiliation(s)
- Susan Duty
- King's College London, Wolfson Centre for Age-Related Diseases, Guy's Campus, London, UK.
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Sheffler DJ, Gregory KJ, Rook JM, Conn PJ. Allosteric modulation of metabotropic glutamate receptors. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2011; 62:37-77. [PMID: 21907906 DOI: 10.1016/b978-0-12-385952-5.00010-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The development of receptor subtype-selective ligands by targeting allosteric sites of G protein-coupled receptors (GPCRs) has proven highly successful in recent years. One GPCR family that has greatly benefited from this approach is the metabotropic glutamate receptors (mGlus). These family C GPCRs participate in the neuromodulatory actions of glutamate throughout the CNS, where they play a number of key roles in regulating synaptic transmission and neuronal excitability. A large number of mGlu subtype-selective allosteric modulators have been identified, the majority of which are thought to bind within the transmembrane regions of the receptor. These modulators can either enhance or inhibit mGlu functional responses and, together with mGlu knockout mice, have furthered the establishment of the physiologic roles of many mGlu subtypes. Numerous pharmacological and receptor mutagenesis studies have been aimed at providing a greater mechanistic understanding of the interaction of mGlu allosteric modulators with the receptor, which have revealed evidence for common allosteric binding sites across multiple mGlu subtypes and the presence for multiple allosteric sites within a single mGlu subtype. Recent data have also revealed that mGlu allosteric modulators can display functional selectivity toward particular signal transduction cascades downstream of an individual mGlu subtype. Studies continue to validate the therapeutic utility of mGlu allosteric modulators as a potential therapeutic approach for a number of disorders including anxiety, schizophrenia, Parkinson's disease, and Fragile X syndrome.
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Affiliation(s)
- Douglas J Sheffler
- Department of Pharmacology, Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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Cui L, Kim YR, Kim HY, Lee SC, Shin HS, Szabó G, Erdélyi F, Kim J, Kim SJ. Modulation of synaptic transmission from primary afferents to spinal substantia gelatinosa neurons by group III mGluRs in GAD65-EGFP transgenic mice. J Neurophysiol 2010; 105:1102-11. [PMID: 21177998 DOI: 10.1152/jn.00108.2010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Group III metabotropic glutamate receptors (mGluRs) are involved in nociceptive transmission in the spinal cord. However, the cellular mechanism underlying the modulation of synaptic transmission from nociceptive primary afferents to dorsal horn neurons by group III mGluRs has yet to be explored. In this study, we used transgenic mice expressing enhanced green fluorescent protein (EGFP) under the control of the glutamate decarboxylase (GAD) 65 promoter to identify specific subpopulations of GABAergic inhibitory interneurons. By GABA immunolabeling, we confirmed the majority of GAD65-EGFP-expressing neurons were GABAergic. Because GAD65-EGFP-expressing neurons have not been examined in detail before, we first investigated the physiological properties of GAD65-EGFP- and non-EGFP-expressing neurons in substantia gelatinosa (SG) of the spinal dorsal horn. Membrane properties, such as the resting membrane potential, membrane capacitance, action potential threshold, and action potential height, differed significantly between these two groups of neurons. Most EGFP-expressing neurons displayed a tonic firing pattern (73% of recorded neurons) and received monosynaptic Aδ and/or C primary afferent inputs (85% of recorded neurons). In contrast, we observed a delayed firing pattern in 53% of non-EGFP-expressing neurons. After identifying the physiological properties of EGFP-expressing neurons, we tested the effects of group III mGluRs on synaptic transmission pharmacologically. A group III mGluR agonist, L-AP4, attenuated Aδ fiber-evoked synaptic transmission but did not affect C fiber-evoked synaptic transmission to EGFP-expressing neurons. Similar primary afferent-specific inhibition by L-AP4 was also observed in non-EGFP-expressing neurons. Moreover, Aδ fiber-evoked synaptic transmission was suppressed by a selective mGluR7 agonist, AMN082. These results suggest that modulation of the synaptic transmission from primary afferents to SG neurons by group III mGluR agonist is specific to the type of nociceptive primary afferents but not to the type of target neurons.
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Affiliation(s)
- Lian Cui
- Department of Physiology, Seoul National University College of Medicine, Yeongeon-dong, Jongro-gu, Seoul 110-799, Korea
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Christov C, González-Bulnes P, Malhaire F, Karabencheva T, Goudet C, Pin JP, Llebaria A, Giraldo J. Integrated Synthetic, Pharmacological, and Computational Investigation of cis-2-(3,5-Dichlorophenylcarbamoyl)cyclohexanecarboxylic Acid Enantiomers As Positive Allosteric Modulators of Metabotropic Glutamate Receptor Subtype 4. ChemMedChem 2010; 6:131-40. [DOI: 10.1002/cmdc.201000378] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Austin PJ, Betts MJ, Broadstock M, O'Neill MJ, Mitchell SN, Duty S. Symptomatic and neuroprotective effects following activation of nigral group III metabotropic glutamate receptors in rodent models of Parkinson's disease. Br J Pharmacol 2010; 160:1741-53. [PMID: 20649576 DOI: 10.1111/j.1476-5381.2010.00820.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Increased glutamatergic innervation of the substantia nigra pars reticulata (SNpr) and pars compacta (SNpc) may contribute to the motor deficits and neurodegeneration, respectively, in Parkinson's disease (PD). This study aimed to establish whether activation of pre-synaptic group III metabotropic glutamate (mGlu) receptors reduced glutamate release in the SN, and provided symptomatic or neuroprotective relief in animal models of PD. EXPERIMENTAL APPROACH Broad-spectrum group III mGlu receptor agonists, O-phospho-l-serine (l-SOP) and l-2-amino-4-phosphonobutyrate (l-AP4), were assessed for their ability to inhibit KCl-evoked [(3)H]-d-aspartate release in rat nigral prisms or inhibit KCl-evoked endogenous glutamate release in the SNpr in vivo using microdialysis. Reversal of akinesia in reserpine-treated rats was assessed following intranigral injection of l-SOP and l-AP4. Finally, the neuroprotective effect of 7 days' supra-nigral treatment with l-AP4 was examined in 6-hydroxydopamine (6-OHDA)-lesioned rats. KEY RESULTS l-SOP and l-AP4 inhibited [(3)H]-d-aspartate release by 33 and 44% respectively. These effects were blocked by the selective group III mGlu antagonist (RS)-alpha-cyclopropyl-4-phosphonophenylglycine (CPPG). l-SOP also reduced glutamate release in the SNpr in vivo by 48%. Injection of l-SOP and l-AP4 into the SNpr reversed reserpine-induced akinesia. Following administration above the SNpc, l-AP4 provided neurochemical, histological and functional protection against 6-OHDA lesion of the nigrostriatal tract. Pretreatment with CPPG inhibited these effects. CONCLUSIONS AND IMPLICATIONS These findings highlight group III mGlu receptors in the SN as potential targets for providing both symptomatic and neuroprotective relief in PD, and indicate that inhibition of glutamate release in the SN may underlie these effects.
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Affiliation(s)
- P J Austin
- Department of Anatomy and Histology, Anderson Stuart Building, University of Sydney, Sydney, NSW, Australia
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Nicoletti F, Bockaert J, Collingridge GL, Conn PJ, Ferraguti F, Schoepp DD, Wroblewski JT, Pin JP. Metabotropic glutamate receptors: from the workbench to the bedside. Neuropharmacology 2010; 60:1017-41. [PMID: 21036182 DOI: 10.1016/j.neuropharm.2010.10.022] [Citation(s) in RCA: 476] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Revised: 10/15/2010] [Accepted: 10/21/2010] [Indexed: 12/24/2022]
Abstract
Metabotropic glutamate (mGlu) receptors were discovered in the mid 1980s and originally described as glutamate receptors coupled to polyphosphoinositide hydrolysis. Almost 6500 articles have been published since then, and subtype-selective mGlu receptor ligands are now under clinical development for the treatment of a variety of disorders such as Fragile-X syndrome, schizophrenia, Parkinson's disease and L-DOPA-induced dyskinesias, generalized anxiety disorder, chronic pain, and gastroesophageal reflux disorder. Prof. Erminio Costa was linked to the early times of the mGlu receptor history, when a few research groups challenged the general belief that glutamate could only activate ionotropic receptors and all metabolic responses to glutamate were secondary to calcium entry. This review moves from those nostalgic times to the most recent advances in the physiology and pharmacology of mGlu receptors, and highlights the role of individual mGlu receptor subtypes in the pathophysiology of human disorders. This article is part of a Special Issue entitled 'Trends in neuropharmacology: in memory of Erminio Costa'.
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Affiliation(s)
- F Nicoletti
- Department of Physiology and Pharmacology, University of Rome, Sapienza, Piazzale Aldo Moro 5, 00185 Rome, Italy.
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Abitbol K, Acher F, Daniel H. Depression of excitatory transmission at PF-PC synapse by group III metabotropic glutamate receptors is provided exclusively by mGluR4 in the rodent cerebellar cortex. J Neurochem 2010; 105:2069-79. [PMID: 18266929 DOI: 10.1111/j.1471-4159.2008.05290.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In the rodent cerebellum, pharmacological activation of group III pre-synaptic metabotropic glutamate receptors (mGluRs) by the broad spectrum agonist L-2-amino-4-phosphonobutyric acid, acutely depresses excitatory synaptic transmission at parallel fiber (PF)-Purkinje cell (PC) synapses. Among the group III mGluR subtypes, cerebellar granule cells express predominantly mGluR4, but also mGluR7 and mGluR8 mRNA. Taking into account that previous functional and pharmacological studies have used group III mGluR broad spectrum agonists that do not differentiate between these various subtypes, their relative contribution to the modulation of glutamatergic transmission at PF-PC synapses remains to be elucidated. In order to clarify this issue, we applied conventional whole-cell patch-clamp recordings and pre-synaptic calcium influx measurements, combined with pharmacological manipulations to rat and mice cerebellar slices. With the use of (1S,2R)-1-amino-2-phosphonomethylcyclopropanecarboxylic acid, a new and selective group III mGluR agonist, N-phenyl-7-(hydroxylimino)cyclopropa[b]-chromen-1a-carboxamide, the specific positive allosteric modulator of mGluR4, (S)-3,4-dicarboxyphenylglycine, a selective mGluR8 agonist, and mGluR4 knock-out mice, we demonstrate that the inhibitory control of group III mGluRs on excitatory neurotransmission at PF-PC synapses of the rodent cerebellar cortex, is totally because of the activation of pre-synaptic mGluR4 autoreceptors.
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Affiliation(s)
- Karine Abitbol
- Laboratoire Pharmacologie de la synapse, CNRS UMR 8619, Institut de Biochimie et de Biophysique Moléculaire et Cellulaire, Université Paris-Sud, Orsay Cedex, France
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Gregory KJ, Dong EN, Meiler J, Conn PJ. Allosteric modulation of metabotropic glutamate receptors: structural insights and therapeutic potential. Neuropharmacology 2010; 60:66-81. [PMID: 20637216 DOI: 10.1016/j.neuropharm.2010.07.007] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Revised: 06/28/2010] [Accepted: 07/06/2010] [Indexed: 10/19/2022]
Abstract
Allosteric modulation of G protein-coupled receptors (GPCRs) represents a novel approach to the development of probes and therapeutics that is expected to enable subtype-specific regulation of central nervous system target receptors. The metabotropic glutamate receptors (mGlus) are class C GPCRs that play important neuromodulatory roles throughout the brain, as such they are attractive targets for therapeutic intervention for a number of psychiatric and neurological disorders including anxiety, depression, Fragile X Syndrome, Parkinson's disease and schizophrenia. Over the last fifteen years, selective allosteric modulators have been identified for many members of the mGlu family. The vast majority of these allosteric modulators are thought to bind within the transmembrane-spanning domains of the receptors to enhance or inhibit functional responses. A combination of mutagenesis-based studies and pharmacological approaches are beginning to provide a better understanding of mGlu allosteric sites. Collectively, when mapped onto a homology model of the different mGlu subtypes based on the β(2)-adrenergic receptor, the previous mutagenesis studies suggest commonalities in the location of allosteric sites across different members of the mGlu family. In addition, there is evidence for multiple allosteric binding pockets within the transmembrane region that can interact to modulate one another. In the absence of a class C GPCR crystal structure, this approach has shown promise with respect to the interpretation of mutagenesis data and understanding structure-activity relationships of allosteric modulator pharmacophores.
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Affiliation(s)
- Karen J Gregory
- Department of Pharmacology, Vanderbilt Program in Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232-0697, USA.
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De Amici M, Dallanoce C, Holzgrabe U, Tränkle C, Mohr K. Allosteric ligands for G protein-coupled receptors: a novel strategy with attractive therapeutic opportunities. Med Res Rev 2010; 30:463-549. [PMID: 19557759 DOI: 10.1002/med.20166] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Allosteric receptor ligands bind to a recognition site that is distinct from the binding site of the endogenous messenger molecule. As a consequence, allosteric agents may attach to receptors that are already transmitter-bound. Ternary complex formation opens an avenue to qualitatively new drug actions at G protein-coupled receptors (GPCRs), in particular receptor subtype selective potentiation of endogenous transmitter action. Consequently, suitable exploitation of allosteric recognition sites as alternative molecular targets could pave the way to a drug discovery paradigm different from those aimed at mimicking or blocking the effects of endogenous (orthosteric) receptor activators. The number of allosteric ligands reported to modulate GPCR function is steadily increasing and some have already reached routine clinical use. This review aims at introducing into this fascinating field of drug discovery and at providing an overview about the achievements that have already been made. Various case examples will be discussed in the framework of GPCR classification (family A, B, and C receptors). In addition, the behavior at muscarinic receptors of hybrid derivatives incorporating both an allosteric and an orthosteric fragment in a common molecular skeleton will be illustrated.
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Affiliation(s)
- Marco De Amici
- Department of Pharmaceutical Sciences Pietro Pratesi, University of Milan, via Mangiagalli 25, 20133 Milano, Italy.
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