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Mazzitelli M, Presto P, Antenucci N, Meltan S, Neugebauer V. Recent Advances in the Modulation of Pain by the Metabotropic Glutamate Receptors. Cells 2022; 11:2608. [PMID: 36010684 PMCID: PMC9406805 DOI: 10.3390/cells11162608] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 08/16/2022] [Accepted: 08/18/2022] [Indexed: 01/22/2023] Open
Abstract
Metabotropic glutamate receptors (mGluR or mGlu) are G-protein coupled receptors activated by the binding of glutamate, the main classical neurotransmitter of the nervous system. Eight different mGluR subtypes (mGluR1-8) have been cloned and are classified in three groups based on their molecular, pharmacological and signaling properties. mGluRs mediate several physiological functions such as neuronal excitability and synaptic plasticity, but they have also been implicated in numerous pathological conditions including pain. The availability of new and more selective allosteric modulators together with the canonical orthosteric ligands and transgenic technologies has led to significant advances in our knowledge about the role of the specific mGluR subtypes in the pathophysiological mechanisms of various diseases. Although development of successful compounds acting on mGluRs for clinical use has been scarce, the subtype-specific-pharmacological manipulation might be a compelling approach for the treatment of several disorders in humans, including pain; this review aims to summarize and update on preclinical evidence for the roles of different mGluRs in the pain system and discusses knowledge gaps regarding mGluR-related sex differences and neuroimmune signaling in pain.
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Affiliation(s)
- Mariacristina Mazzitelli
- Department of Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Peyton Presto
- Department of Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Nico Antenucci
- Department of Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Shakira Meltan
- Department of Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Volker Neugebauer
- Department of Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
- Center of Excellence for Translational Neuroscience and Therapeutics, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
- Garrison Institute on Aging, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
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Witkin JM, Pandey KP, Smith JL. Clinical investigations of compounds targeting metabotropic glutamate receptors. Pharmacol Biochem Behav 2022; 219:173446. [PMID: 35987339 DOI: 10.1016/j.pbb.2022.173446] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 06/22/2022] [Accepted: 08/08/2022] [Indexed: 11/15/2022]
Abstract
Pharmacological modulation of glutamate has long been considered to be of immense therapeutic utility. The metabotropic glutamate receptors (mGluRs) are potential targets for safely altering glutamate-driven excitation. Data support the potential therapeutic use of mGluR modulators in the treatment of anxiety, depression, schizophrenia, and other psychiatric disorders, pain, epilepsy, as well as neurodegenerative and neurodevelopmental disorders. For each of the three mGluR groups, compounds have been constructed that produce either potentiation or functional blockade. PET ligands for mGlu5Rs have been studied in a range of patient populations and several mGlu5R antagonists have been tested for potential efficacy in patients including mavoglurant, diploglurant, basimglurant, GET 73, and ADX10059. Efficacy with mGlu5R antagonists has been reported in trials with patients with gastroesophageal reflux disease; data from patients with Parkinson's disease or Fragile X syndrome have not been as robust as hoped. Fenobam was approved for use as an anxiolytic prior to its recognition as an mGlu5R antagonist. mGlu2/3R agonists (pomaglumated methionil) and mGlu2R agonists (JNJ-40411813, AZD 8529, and LY2979165) have been studied in patients with schizophrenia with promising but mixed results. Antagonists of mGlu2/3Rs (decoglurant and TS-161) have been studied in depression where TS-161 has advanced into a planned Phase 2 study in treatment-resistant depression. The Group III mGluRs are the least developed of the mGluR receptor targets. The mGlu4R potentiator, foliglurax, did not meet its primary endpoint in patients with Parkinson's disease. Ongoing efforts to develop mGluR-targeted compounds continue to promise these glutamate modulators as medicines for psychiatric and neurological disorders.
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Affiliation(s)
- Jeffrey M Witkin
- Laboratory of Antiepileptic Drug Discovery, Ascension St. Vincent, Indianapolis, IN, USA; Department of Chemistry & Biochemistry, Milwaukee Institute of Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, WI, USA; RespireRx Pharmaceuticals Inc, Glen Rock, NJ, USA.
| | - Kamal P Pandey
- Department of Chemistry & Biochemistry, Milwaukee Institute of Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Jodi L Smith
- Laboratory of Antiepileptic Drug Discovery, Ascension St. Vincent, Indianapolis, IN, USA
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Wang X, Ali N, Lin CLG. Emerging role of glutamate in the pathophysiology and therapeutics of Gulf War illness. Life Sci 2021; 280:119609. [PMID: 33991547 DOI: 10.1016/j.lfs.2021.119609] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 05/03/2021] [Accepted: 05/04/2021] [Indexed: 11/20/2022]
Abstract
Gulf War illness (GWI) is a chronic and multi-symptomatic disorder affecting veterans who served in the Gulf War. The commonly reported symptoms in GWI veterans include mood problems, cognitive impairment, muscle and joint pain, migraine/headache, chronic fatigue, gastrointestinal complaints, skin rashes, and respiratory problems. Neuroimaging studies have revealed significant brain structure alterations in GWI veterans, including subcortical atrophy, decreased volume of the hippocampus, reduced total grey and white matter, and increased brain white matter axial diffusivity. These brain changes may contribute to or increase the severities of the GWI-related symptoms. Epidemiological studies have revealed that neurotoxic exposures and stress may be significant contributors to the development of GWI. However, the mechanism underlying how the exposure and stress could contribute to the multi-symptomatic disorder of GWI remains unclear. We and others have demonstrated that rodent models exposed to GW-related agents and stress exhibited higher extracellular glutamate levels, as well as impaired structure and function of glutamatergic synapses. Restoration of the glutamatergic synapses ameliorated the GWI-related pathological and behavioral deficits. Moreover, recent studies showed that a low-glutamate diet reduced multiple symptoms in GWI veterans, suggesting an important role of the glutamatergic system in GWI. Currently, growing evidence has indicated that abnormal glutamate neurotransmission may contribute to the GWI symptoms. This review summarizes the potential roles of glutamate dyshomeostasis and dysfunction of the glutamatergic system in linking the initial cause to the multi-symptomatic outcomes in GWI and suggests the glutamatergic system as a therapeutic target for GWI.
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Affiliation(s)
- Xueqin Wang
- Department of Neuroscience, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Noor Ali
- Department of Neuroscience, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Chien-Liang Glenn Lin
- Department of Neuroscience, College of Medicine, The Ohio State University, Columbus, OH, USA.
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Selective activation of metabotropic glutamate receptor 7 blocks paclitaxel-induced acute neuropathic pain and suppresses spinal glial reactivity in rats. Psychopharmacology (Berl) 2021; 238:107-119. [PMID: 33089875 DOI: 10.1007/s00213-020-05662-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 09/10/2020] [Indexed: 12/30/2022]
Abstract
RATIONALE Paclitaxel-induced acute pain syndrome (P-APS), characterized by deep muscle aches and arthralgia, occurs in more than 70% of patients who receive paclitaxel. P-APS can be debilitating for patients and lead to reductions and discontinuation of potentially curable therapy. Despite being relatively common in clinical practice, no clear treatment exists for P-APS and the underlying mechanisms remain poorly defined. Regulation of glutamatergic transmission by metabotropic glutamate receptors (mGluRs) has received growing attention with respect to its role in neuropathic pain. To our knowledge, no study has been conducted on alterations and functions of group III mGluR7 signaling in P-APS. OBJECTIVES In the present study, we determined whether a single administration of paclitaxel induces glutamatergic alterations and whether mGluR7 activation blocks paclitaxel-induced neuropathic pain by suppressing glial reactivity in the spinal cord. RESULTS A single paclitaxel injection dose-dependently induced acute mechanical and thermal hypersensitivity, and was associated with increased glutamate level accompanied by reduction in mGluR7 expression in the spinal cord. Selective activation of mGluR7 by its positive allosteric modulator, AMN082, blocked the development of paclitaxel-induced acute mechanical and thermal hypersensitivity, without affecting the normal pain behavior of control rats. Moreover, activation of mGluR7 by AMN082 inhibited glial reactivity and decreased pro-inflammatory cytokine release during P-APS. Abortion of spinal glial reaction to paclitaxel alleviated paclitaxel-induced acute mechanical and thermal hypersensitivity. CONCLUSIONS There results support the hypothesis that spinal mGluR7 signaling plays an important role in P-APS; Selective activation of mGluR7 by its positive allosteric modulator, AMN082, blocks P-APS in part by reducing spinal glial reactivity and neuroinflammatory process.
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Boccella S, Marabese I, Guida F, Luongo L, Maione S, Palazzo E. The Modulation of Pain by Metabotropic Glutamate Receptors 7 and 8 in the Dorsal Striatum. Curr Neuropharmacol 2020; 18:34-50. [PMID: 31210112 PMCID: PMC7327935 DOI: 10.2174/1570159x17666190618121859] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 04/01/2019] [Accepted: 05/31/2019] [Indexed: 12/28/2022] Open
Abstract
The dorsal striatum, apart from controlling voluntary movement, displays a recently demonstrated pain inhibition. It is connected to the descending pain modulatory system and in particular to the rostral ventromedial medulla through the medullary dorsal reticular nucleus. Diseases of the basal ganglia, such as Parkinson's disease, in addition to being characterized by motor disorders, are associated with pain and hyperactivation of the excitatory transmission. A way to counteract glutamatergic hyperactivation is through the activation of group III metabotropic glutamate receptors (mGluRs), which are located on presynaptic terminals inhibiting neurotransmitter release. So far the mGluRs of group III have been the least investigated, owing to a lack of selective tools. More recently, selective ligands for each mGluR of group III, in particular positive and negative allosteric modulators, have been developed and the role of each subtype is starting to emerge. The neuroprotective potential of group III mGluRs in pathological conditions, such as those characterized by elevate glutamate, has been recently shown. In the dorsal striatum, mGluR7 and mGluR8 are located at glutamatergic corticostriatal terminals and their stimulation inhibits pain in pathological conditions such as neuropathic pain. The two receptors in the dorsal striatum have instead a different role in pain control in normal conditions. This review will discuss recent results focusing on the contribution of mGluR7 and mGluR8 in the dorsal striatal control of pain. The role of mGluR4, whose antiparkinsonian activity is widely reported, will also be addressed.
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Affiliation(s)
- Serena Boccella
- Department of Experimental Medicine, Pharmacology Division, University of Campania "L. Vanvitelli", Via Costantinopoli 16, 80138 Naples, Italy
| | - Ida Marabese
- Department of Experimental Medicine, Pharmacology Division, University of Campania "L. Vanvitelli", Via Costantinopoli 16, 80138 Naples, Italy
| | - Francesca Guida
- Department of Experimental Medicine, Pharmacology Division, University of Campania "L. Vanvitelli", Via Costantinopoli 16, 80138 Naples, Italy
| | - Livio Luongo
- Department of Experimental Medicine, Pharmacology Division, University of Campania "L. Vanvitelli", Via Costantinopoli 16, 80138 Naples, Italy
| | - Sabatino Maione
- Department of Experimental Medicine, Pharmacology Division, University of Campania "L. Vanvitelli", Via Costantinopoli 16, 80138 Naples, Italy
| | - Enza Palazzo
- Department of Experimental Medicine, Pharmacology Division, University of Campania "L. Vanvitelli", Via Costantinopoli 16, 80138 Naples, Italy
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Cid JM, Lavreysen H, Tresadern G, Pérez-Benito L, Tovar F, Fontana A, Trabanco AA. Computationally Guided Identification of Allosteric Agonists of the Metabotropic Glutamate 7 Receptor. ACS Chem Neurosci 2019; 10:1043-1054. [PMID: 30216043 DOI: 10.1021/acschemneuro.8b00331] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The metabotropic glutamate 7 (mGlu7) receptor belongs to the group III of mGlu receptors. Since the mGlu7 receptor can control excitatory neurotransmission in the hippocampus and cortex, modulation of the receptor may have therapeutic benefit in several CNS diseases. However, mGlu7 remains relatively unexplored among the eight known mGlu receptors partly because of the limited availability of tool compounds to interrogate its potential therapeutic utility. Here we report the discovery of a new class of mGlu7 allosteric agonists. Hits originating from virtual screening were followed up with further analogue searching and screening, leading to a novel series of mGlu7 allosteric agonists. Guided by docking into a structural model of the mGlu7 receptor the initial hit 5 was successfully optimized to analogues with comparable potencies and more attractive drug-like attributes than AMN082.
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Affiliation(s)
- Jose María Cid
- Janssen Research and Development, Calle Jarama 75A, Toledo 45007, Spain
| | - Hilde Lavreysen
- Janssen Research and Development, Turnhoutseweg 30, 2440 Beerse, Belgium
| | - Gary Tresadern
- Janssen Research and Development, Turnhoutseweg 30, 2440 Beerse, Belgium
| | - Laura Pérez-Benito
- Laboratori de Medicina Computacional Unitat de Bioestadistica, Facultat de Medicina, Universitat Autonoma de Barcelona, Bellaterra 08193, Spain
| | - Fulgencio Tovar
- Villapharma Research
S.L., Parque Tecnológico de Fuente Álamo. Ctra. El Estrecho-Lobosillo, Km. 2.5- Av. Azul, 30320 Fuente Álamo de Murcia, Murcia, Spain
| | - Alberto Fontana
- Janssen Research and Development, Calle Jarama 75A, Toledo 45007, Spain
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Pereira V, Goudet C. Emerging Trends in Pain Modulation by Metabotropic Glutamate Receptors. Front Mol Neurosci 2019; 11:464. [PMID: 30662395 PMCID: PMC6328474 DOI: 10.3389/fnmol.2018.00464] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 11/30/2018] [Indexed: 12/20/2022] Open
Abstract
Pain is an essential protective mechanism meant to prevent tissue damages in organisms. On the other hand, chronic or persistent pain caused, for example, by inflammation or nerve injury is long lasting and responsible for long-term disability in patients. Therefore, chronic pain and its management represents a major public health problem. Hence, it is critical to better understand chronic pain molecular mechanisms to develop innovative and efficient drugs. Over the past decades, accumulating evidence has demonstrated a pivotal role of glutamate in pain sensation and transmission, supporting glutamate receptors as promising potential targets for pain relieving drug development. Glutamate is the most abundant excitatory neurotransmitter in the brain. Once released into the synapse, glutamate acts through ionotropic glutamate receptors (iGluRs), which are ligand-gated ion channels triggering fast excitatory neurotransmission, and metabotropic glutamate receptors (mGluRs), which are G protein-coupled receptors modulating synaptic transmission. Eight mGluRs subtypes have been identified and are divided into three classes based on their sequence similarities and their pharmacological and biochemical properties. Of note, all mGluR subtypes (except mGlu6 receptor) are expressed within the nociceptive pathways where they modulate pain transmission. This review will address the role of mGluRs in acute and persistent pain processing and emerging pharmacotherapies for pain management.
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Affiliation(s)
- Vanessa Pereira
- IGF, CNRS, INSERM, Univ. de Montpellier, Montpellier, France
| | - Cyril Goudet
- IGF, CNRS, INSERM, Univ. de Montpellier, Montpellier, France
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8
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Metabotropic glutamate receptor subtype 7 in the dorsal striatum oppositely modulates pain in sham and neuropathic rats. Neuropharmacology 2018; 135:86-99. [PMID: 29505788 DOI: 10.1016/j.neuropharm.2018.03.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 02/23/2018] [Accepted: 03/01/2018] [Indexed: 11/24/2022]
Abstract
The study investigated the role of the metabotropic glutamate receptor subtype 7 (mGluR7) in pain signalling in the dorsal striatum of sham and neuropathic rats. Supraspinal circuitries involved in the dorsal striatum control of pain were also explored. In the sham rats, microinjection of N,N'-bis(diphenylmethyl)-1,2-ethanediamine (AMN082), a selective mGluR7 positive allosteric modulator, into the dorsal striatum, facilitated pain, increased the activity of the ON cells and inhibited the activity of the OFF cells in the rostral ventromedial medulla, and decreased glutamate levels in the dorsal striatum. Conversely, AMN082 inhibited pain and the activity of the ON cells while increased the activity of the OFF cells in rats with spared nerve injury (SNI) of the sciatic nerve. AMN082 also decreased glutamate levels in the dorsal striatum of SNI rats. The effect of AMN082 on mechanical allodynia and glutamate release was blocked by 6-(2,4-dimethylphenyl)-2-ethyl-6,7-dihydro-4(5H)-benzoxazolone (ADX71743), a selective mGluR7 negative allosteric modulator. Moreover, in the sham rats, AMN082 increased the activity of total nociceptive convergent neurons in the dorsal reticular nucleus while in the SNI rats, such activity was decreased. The administration of lidocaine into the subthalamic nucleus abolished the effect of AMN082 on the total nociceptive convergent neurons in the sham rats but not in the SNI rats. Thus, the dual effect of mGluR7 in facilitating or inhibiting pain responses may be due to the recruitment of different pathways of the basal ganglia, the indirect or direct pathway, in physiological or pathological conditions, respectively.
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Gawel K, Jenda-Wojtanowska M, Gibula-Bruzda E, Kedzierska E, Filarowska J, Marszalek-Grabska M, Wojtanowski KK, Komsta L, Talarek S, Kotlinska JH. The influence of AMN082, metabotropic glutamate receptor 7 (mGlu7) allosteric agonist on the acute and chronic antinociceptive effects of morphine in the tail-immersion test in mice: Comparison with mGlu5 and mGlu2/3 ligands. Physiol Behav 2017; 185:112-120. [PMID: 29294304 DOI: 10.1016/j.physbeh.2017.12.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 12/18/2017] [Accepted: 12/29/2017] [Indexed: 11/19/2022]
Abstract
Preclinical data indicated that the metabotropic glutamate receptors 5 (mGlu5) and glutamate receptors 2/3 (mGlu2/3) are involved in modulating morphine antinociception. However, little is known about the role of metabotropic glutamate receptors 7 (mGlu7) in this phenomenon. We compared the effects of AMN082 (0.1, 1 or 5mg/kg, ip), a selective mGlu7 allosteric agonist, LY354740 (0.1, 1 or 5mg/kg, ip), an mGlu2/3 agonist and MTEP (0.1, 1 or 5mg/kg, ip), a selective mGlu5 antagonist, on the acute antinociceptive effect of morphine (5mg/kg, sc) and also on the development and expression of tolerance to morphine analgesia in the tail-immersion test in mice. To determine the role of mGlu7 in morphine tolerance, and the association of the mGlu7 effect with the N-methyl-d-aspartate (NMDA) receptors regulation, we used MMPIP (10mg/kg, ip), a selective mGlu7 antagonist and MK-801, a NMDA antagonist. Herein, the acute administration of AMN082, MTEP or LY354740 alone failed to evoked antinociception, and did not affect morphine (5mg/kg, sc) antinociception. However, these ligands inhibited the development of morphine tolerance, and we indicated that MMPIP reversed the inhibitory effect of AMN082. When given together, the non-effective doses of AMN082 and MK-801 did not alter the tolerance to morphine. Thus, mGlu7, similarly to mGlu2/3 and mGlu5, are involved in the development of tolerance to the antinociceptive effects of morphine, but not in the acute morphine antinociception. Furthermore, while mGlu7 are engaged in the development of morphine tolerance, no interaction exists between mGlu7 and NMDA receptors in this phenomenon.
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Affiliation(s)
- K Gawel
- Department of Pharmacology and Pharmacodynamics, Medical University, Lublin, Poland; Department of Experimental and Clinical Pharmacology, Medical University, Lublin, Poland
| | - M Jenda-Wojtanowska
- Department of Pharmacology and Pharmacodynamics, Medical University, Lublin, Poland
| | - E Gibula-Bruzda
- Department of Pharmacology and Pharmacodynamics, Medical University, Lublin, Poland
| | - E Kedzierska
- Department of Pharmacology and Pharmacodynamics, Medical University, Lublin, Poland
| | - J Filarowska
- Department of Pharmacology and Pharmacodynamics, Medical University, Lublin, Poland
| | - M Marszalek-Grabska
- Department of Pharmacology and Pharmacodynamics, Medical University, Lublin, Poland
| | - K K Wojtanowski
- Department of Pharmacognosy with Medicinal Plant Unit, Medical University, Lublin, Poland
| | - L Komsta
- Department of Medicinal Chemistry, Medical University, Lublin, Poland
| | - S Talarek
- Department of Pharmacology and Pharmacodynamics, Medical University, Lublin, Poland
| | - J H Kotlinska
- Department of Pharmacology and Pharmacodynamics, Medical University, Lublin, Poland.
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Lian YN, Lu Q, Chang JL, Zhang Y. The role of glutamate and its receptors in central nervous system in stress-induced hyperalgesia. Int J Neurosci 2017; 128:283-290. [DOI: 10.1080/00207454.2017.1387112] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Yan-Na Lian
- Department of Physiology, Harbin Medical University, Harbin, P. R. China
| | - Qi Lu
- Department of Physiology, Harbin Medical University, Harbin, P. R. China
| | - Jin-Long Chang
- Department of Physiology, Harbin Medical University, Harbin, P. R. China
| | - Ying Zhang
- Department of Physiology, Harbin Medical University, Harbin, P. R. China
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11
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Palazzo E, Marabese I, Luongo L, Guida F, de Novellis V, Maione S. Nociception modulation by supraspinal group III metabotropic glutamate receptors. J Neurochem 2017; 141:507-519. [DOI: 10.1111/jnc.13725] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 06/15/2016] [Accepted: 06/20/2016] [Indexed: 02/02/2023]
Affiliation(s)
- Enza Palazzo
- Department of Experimental Medicine; The Second University of Naples; Naples Italy
| | - Ida Marabese
- Department of Experimental Medicine; The Second University of Naples; Naples Italy
| | - Livio Luongo
- Department of Experimental Medicine; The Second University of Naples; Naples Italy
| | - Francesca Guida
- Department of Experimental Medicine; The Second University of Naples; Naples Italy
| | - Vito de Novellis
- Department of Experimental Medicine; The Second University of Naples; Naples Italy
| | - Sabatino Maione
- Department of Experimental Medicine; The Second University of Naples; Naples Italy
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12
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Kahl E, Fendt M. Metabotropic Glutamate Receptors 7 within the Nucleus Accumbens are Involved in Relief Learning in Rats. Curr Neuropharmacol 2017; 14:405-12. [PMID: 27296637 PMCID: PMC4983753 DOI: 10.2174/1570159x13666150425002017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 03/03/2015] [Accepted: 04/22/2016] [Indexed: 11/26/2022] Open
Abstract
Relief learning is an appetitive association of a formally neutral cue with relief induced by the offset of an aversive stimulus. Since the nucleus accumbens mediates relief learning and accumbal metabotropic glutamate receptors 7 (mGluR7) modulate appetitive-like processes, we hypothesized that accumbal mGluR7 may be involved in the modulation of relief learning. Therefore, we injected the allosteric mGluR7 agonist AMN082 into the nucleus accumbens and tested the effects of these injections on acquisition and expression of relief memory, as well as on the reactivity to electric stimuli. AMN082 injections blocked acquisition but not expression of relief memory. In addition, accumbal AMN082 injections strongly reduced the locomotor reactivity to electric stimuli indicating antinociceptive effects. These antinociceptive effects might be causal for the blockade of relief learning after AMN082 injections. Taken together, the present study indicates that functional activation of accumbal mGluR7 has antinociceptive effects that interfere with relief learning.
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Affiliation(s)
| | - Markus Fendt
- Institute for Pharmacology and Toxicology, Leipziger Straße 44, D-39120 Magdeburg, Germany.
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13
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Rogoz K, Aresh B, Freitag FB, Pettersson H, Magnúsdóttir EI, Larsson Ingwall L, Haddadi Andersen H, Franck MCM, Nagaraja C, Kullander K, Lagerström MC. Identification of a Neuronal Receptor Controlling Anaphylaxis. Cell Rep 2016; 14:370-9. [DOI: 10.1016/j.celrep.2015.12.033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 10/20/2015] [Accepted: 12/03/2015] [Indexed: 12/31/2022] Open
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14
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Moloney RD, Golubeva AV, O'Connor RM, Kalinichev M, Dinan TG, Cryan JF. Negative allosteric modulation of the mGlu7 receptor reduces visceral hypersensitivity in a stress-sensitive rat strain. Neurobiol Stress 2015; 2:28-33. [PMID: 26844237 PMCID: PMC4721404 DOI: 10.1016/j.ynstr.2015.04.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Revised: 03/15/2015] [Accepted: 04/03/2015] [Indexed: 11/19/2022] Open
Abstract
Glutamate, the main excitatory neurotransmitter in the central nervous system, exerts its effect through ionotropic and metabotropic receptors. Of these, group III mGlu receptors (mGlu 4, 6, 7, 8) are among the least studied due to a lack of pharmacological tools. mGlu7 receptors, the most highly conserved isoform, are abundantly distributed in the brain, especially in regions, such as the amygdala, known to be crucial for the emotional processing of painful stimuli. Visceral hypersensitivity is a poorly understood phenomenon manifesting as an increased sensitivity to visceral stimuli. Glutamate has long been associated with somatic pain processing leading us to postulate that crossover may exist between these two modalities. Moreover, stress has been shown to exacerbate visceral pain. ADX71743 is a novel, centrally penetrant, negative allosteric modulator of mGlu7 receptors. Thus, we used this tool to explore the possible involvement of this receptor in the mediation of visceral pain in a stress-sensitive model of visceral hypersensitivity, namely the Wistar Kyoto (WKY) rat. ADX71743 reduced visceral hypersensitivity in the WKY rat as exhibited by increased visceral sensitivity threshold with concomitant reductions in total number of pain behaviours. Moreover, AD71743 increased total distance and distance travelled in the inner zone of the open field. These findings show, for what is to our knowledge, the first time, that mGlu7 receptor signalling plays a role in visceral pain processing. Thus, negative modulation of the mGlu7 receptor may be a plausible target for the amelioration of stress-induced visceral pain where there is a large unmet medical need.
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Affiliation(s)
- Rachel D. Moloney
- Laboratory of Neurogastroenterology, Alimentary Pharmabiotic Centre, Biosciences Institute, University College Cork, Ireland
- Department of Psychiatry, University College Cork, Ireland
| | - Anna V. Golubeva
- Laboratory of Neurogastroenterology, Alimentary Pharmabiotic Centre, Biosciences Institute, University College Cork, Ireland
| | | | | | - Timothy G. Dinan
- Laboratory of Neurogastroenterology, Alimentary Pharmabiotic Centre, Biosciences Institute, University College Cork, Ireland
- Department of Psychiatry, University College Cork, Ireland
| | - John F. Cryan
- Laboratory of Neurogastroenterology, Alimentary Pharmabiotic Centre, Biosciences Institute, University College Cork, Ireland
- Department of Anatomy and Neuroscience, University College Cork, Ireland
- Corresponding author. Dept Anatomy & Neuroscience, Room 386, Western Gateway Building, University College Cork, Western Rd., Cork, Ireland.
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15
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Therapeutic potential of group III metabotropic glutamate receptor ligands in pain. Curr Opin Pharmacol 2015; 20:64-72. [DOI: 10.1016/j.coph.2014.11.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 11/18/2014] [Accepted: 11/21/2014] [Indexed: 11/22/2022]
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Jalan-Sakrikar N, Field JR, Klar R, Mattmann M, Gregory KJ, Zamorano R, Engers DW, Bollinger SR, Weaver CD, Days EL, Lewis LM, Utley TJ, Hurtado M, Rigault D, Acher F, Walker AG, Melancon BJ, Wood MR, Lindsley C, Conn PJ, Xiang Z, Hopkins CR, Niswender CM. Identification of positive allosteric modulators VU0155094 (ML397) and VU0422288 (ML396) reveals new insights into the biology of metabotropic glutamate receptor 7. ACS Chem Neurosci 2014; 5:1221-37. [PMID: 25225882 PMCID: PMC4306484 DOI: 10.1021/cn500153z] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 09/15/2014] [Indexed: 11/29/2022] Open
Abstract
Metabotropic glutamate receptor 7 (mGlu7) is a member of the group III mGlu receptors (mGlus), encompassed by mGlu4, mGlu6, mGlu7, and mGlu8. mGlu7 is highly expressed in the presynaptic active zones of both excitatory and inhibitory synapses, and activation of the receptor regulates the release of both glutamate and GABA. mGlu7 is thought to be a relevant therapeutic target for a number of neurological and psychiatric disorders, and polymorphisms in the GRM7 gene have been linked to autism, depression, ADHD, and schizophrenia. Here we report two new pan-group III mGlu positive allosteric modulators, VU0155094 and VU0422288, which show differential activity at the various group III mGlus. Additionally, both compounds show probe dependence when assessed in the presence of distinct orthosteric agonists. By pairing studies of these nonselective compounds with a synapse in the hippocampus that expresses only mGlu7, we have validated activity of these compounds in a native tissue setting. These studies provide proof-of-concept evidence that mGlu7 activity can be modulated by positive allosteric modulation, paving the way for future therapeutics development.
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Affiliation(s)
- Nidhi Jalan-Sakrikar
- Department of Pharmacology and Vanderbilt Center
for Neuroscience Drug Discovery, Department of Pharmacology and
Vanderbilt Institute of Chemical Biology, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - Julie R. Field
- Department of Pharmacology and Vanderbilt Center
for Neuroscience Drug Discovery, Department of Pharmacology and
Vanderbilt Institute of Chemical Biology, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - Rebecca Klar
- Department of Pharmacology and Vanderbilt Center
for Neuroscience Drug Discovery, Department of Pharmacology and
Vanderbilt Institute of Chemical Biology, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - Margrith
E. Mattmann
- Department of Pharmacology and Vanderbilt Center
for Neuroscience Drug Discovery, Department of Pharmacology and
Vanderbilt Institute of Chemical Biology, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - Karen J. Gregory
- Drug
Discovery Biology, Monash Institute of Pharmaceutical
Sciences, Parkville, VIC 3052, Australia
| | - Rocio Zamorano
- Department of Pharmacology and Vanderbilt Center
for Neuroscience Drug Discovery, Department of Pharmacology and
Vanderbilt Institute of Chemical Biology, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - Darren W. Engers
- Department of Pharmacology and Vanderbilt Center
for Neuroscience Drug Discovery, Department of Pharmacology and
Vanderbilt Institute of Chemical Biology, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - Sean R. Bollinger
- Department of Pharmacology and Vanderbilt Center
for Neuroscience Drug Discovery, Department of Pharmacology and
Vanderbilt Institute of Chemical Biology, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - C. David Weaver
- Department of Pharmacology and Vanderbilt Center
for Neuroscience Drug Discovery, Department of Pharmacology and
Vanderbilt Institute of Chemical Biology, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - Emily L. Days
- Department of Pharmacology and Vanderbilt Center
for Neuroscience Drug Discovery, Department of Pharmacology and
Vanderbilt Institute of Chemical Biology, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - L. Michelle Lewis
- Department of Pharmacology and Vanderbilt Center
for Neuroscience Drug Discovery, Department of Pharmacology and
Vanderbilt Institute of Chemical Biology, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - Thomas J. Utley
- Department of Pharmacology and Vanderbilt Center
for Neuroscience Drug Discovery, Department of Pharmacology and
Vanderbilt Institute of Chemical Biology, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - Miguel Hurtado
- Department of Pharmacology and Vanderbilt Center
for Neuroscience Drug Discovery, Department of Pharmacology and
Vanderbilt Institute of Chemical Biology, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37212, United States
| | | | | | - Adam G. Walker
- Department of Pharmacology and Vanderbilt Center
for Neuroscience Drug Discovery, Department of Pharmacology and
Vanderbilt Institute of Chemical Biology, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - Bruce J. Melancon
- Department of Pharmacology and Vanderbilt Center
for Neuroscience Drug Discovery, Department of Pharmacology and
Vanderbilt Institute of Chemical Biology, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - Michael R. Wood
- Department of Pharmacology and Vanderbilt Center
for Neuroscience Drug Discovery, Department of Pharmacology and
Vanderbilt Institute of Chemical Biology, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - Craig
W. Lindsley
- Department of Pharmacology and Vanderbilt Center
for Neuroscience Drug Discovery, Department of Pharmacology and
Vanderbilt Institute of Chemical Biology, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - P. Jeffrey Conn
- Department of Pharmacology and Vanderbilt Center
for Neuroscience Drug Discovery, Department of Pharmacology and
Vanderbilt Institute of Chemical Biology, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - Zixiu Xiang
- Department of Pharmacology and Vanderbilt Center
for Neuroscience Drug Discovery, Department of Pharmacology and
Vanderbilt Institute of Chemical Biology, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - Corey R. Hopkins
- Department of Pharmacology and Vanderbilt Center
for Neuroscience Drug Discovery, Department of Pharmacology and
Vanderbilt Institute of Chemical Biology, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - Colleen M. Niswender
- Department of Pharmacology and Vanderbilt Center
for Neuroscience Drug Discovery, Department of Pharmacology and
Vanderbilt Institute of Chemical Biology, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37212, United States
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17
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Goswami SC, Mishra SK, Maric D, Kaszas K, Gonnella GL, Clokie SJ, Kominsky HD, Gross JR, Keller JM, Mannes AJ, Hoon MA, Iadarola MJ. Molecular signatures of mouse TRPV1-lineage neurons revealed by RNA-Seq transcriptome analysis. THE JOURNAL OF PAIN 2014; 15:1338-1359. [PMID: 25281809 DOI: 10.1016/j.jpain.2014.09.010] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 09/10/2014] [Accepted: 09/19/2014] [Indexed: 12/22/2022]
Abstract
UNLABELLED Disorders of pain neural systems are frequently chronic and, when recalcitrant to treatment, can severely degrade the quality of life. The pain pathway begins with sensory neurons in dorsal root or trigeminal ganglia, and the neuronal subpopulations that express the transient receptor potential cation channel, subfamily V, member 1 (TRPV1) ion channel transduce sensations of painful heat and inflammation and play a fundamental role in clinical pain arising from cancer and arthritis. In the present study, we elucidate the complete transcriptomes of neurons from the TRPV1 lineage and a non-TRPV1 neuroglial population in sensory ganglia through the combined application of next-gen deep RNA-Seq, genetic neuronal labeling with fluorescence-activated cell sorting, or neuron-selective chemoablation. RNA-Seq accurately quantitates gene expression, a difficult parameter to determine with most other methods, especially for very low and very high expressed genes. Differentially expressed genes are present at every level of cellular function from the nucleus to the plasma membrane. We identified many ligand receptor pairs in the TRPV1 population, suggesting that autonomous presynaptic regulation may be a major regulatory mechanism in nociceptive neurons. The data define, in a quantitative, cell population-specific fashion, the molecular signature of a distinct and clinically important group of pain-sensing neurons and provide an overall framework for understanding the transcriptome of TRPV1 nociceptive neurons. PERSPECTIVE Next-gen RNA-Seq, combined with molecular genetics, provides a comprehensive and quantitative measurement of transcripts in TRPV1 lineage neurons and a contrasting transcriptome from non-TRPV1 neurons and cells. The transcriptome highlights previously unrecognized protein families, identifies multiple molecular circuits for excitatory or inhibitory autocrine and paracrine signaling, and suggests new combinatorial approaches to pain control.
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Affiliation(s)
- Samridhi C Goswami
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Santosh K Mishra
- Molecular Genetics Unit, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research, Bethesda, Maryland
| | - Dragan Maric
- Laboratory of Neurophysiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Krisztian Kaszas
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Gian Luigi Gonnella
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Samuel J Clokie
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Hal D Kominsky
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Jacklyn R Gross
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Jason M Keller
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Andrew J Mannes
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Mark A Hoon
- Molecular Genetics Unit, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research, Bethesda, Maryland
| | - Michael J Iadarola
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland.
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Palazzo E, Marabese I, de Novellis V, Rossi F, Maione S. Supraspinal metabotropic glutamate receptors: a target for pain relief and beyond. Eur J Neurosci 2014; 39:444-54. [PMID: 24494684 DOI: 10.1111/ejn.12398] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 09/20/2013] [Accepted: 09/23/2013] [Indexed: 01/09/2023]
Abstract
Glutamate is the main excitatory neurotransmitter in the central nervous system, controlling the majority of synapses. Apart from neurodegenerative diseases, growing evidence suggests that glutamate is involved in psychiatric and neurological disorders, including pain. Glutamate signaling is mediated via ionotropic glutamate receptors (iGluRs) and metabotropic glutamate receptors (mGluRs). So far, drugs acting via modulation of glutamatergic system are few in number, and all are associated with iGluRs and important side effects. The glutamatergic system may be finely modulated by mGluRs. Signaling via these receptors is slower and longer-lasting, and permits fine-tuning of glutamate transmission. There have been eight mGluRs cloned to date (mGluR1-mGluR8), and these are further divided into three groups on the basis of sequence homology, pharmacological profile, and second messenger signaling. The pattern of expression of mGluRs along the pain neuraxis makes them suitable substrates for the design of novel analgesics. This review will focus on the supraspinal mGluRs, whose pharmacological manipulation generates a variety of effects, which depend on the synaptic location, the cell type on which they are located, and the expression in particular pain modulation areas, such as the periaqueductal gray, which plays a major role in the descending modulation of pain, and the central nucleus of the amygdala, which is an important center for the processing of emotional information associated with pain. A particular emphasis will also be given to the novel selective mGluR subtype ligands, as well as positive and negative allosteric modulators, which have permitted discrimination of the individual roles of the different mGluR subtypes, and subtle modulation of central nervous system functioning and related disorders.
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Affiliation(s)
- Enza Palazzo
- Department of Anaesthesiology, Surgery and Emergency, The Second University of Naples, Piazza Luigi Miraglia 2, 80138, Naples, Italy
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19
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G S, Suvarna P, Hadigal S, Kamath P, Prabhu N, Shenoy K A, LC P. Can Metabotropic Glutamate Receptor 7 (mGluR 7) be a Novel Target for Analgesia? J Clin Diagn Res 2014; 8:HC16-8. [PMID: 25386457 PMCID: PMC4225909 DOI: 10.7860/jcdr/2014/10377.4884] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 07/16/2014] [Indexed: 11/24/2022]
Abstract
INTRODUCTION The present study was carried out to study the role of metabotropic glutamate receptor 7 (mGluR7) using its agonist, N,N'-bis(diphenylmethyl)-1,-ethanediamine (AMN082) for nociceptive stimuli, in animal models. By conducting this research, we aim to introduce a novel target for acute pain management. OBJECTIVE To study the role of metabotropic glutamate receptor 7 (mGluR7), in analgesia, using mGluR7 agonist AMN082 in animal models. MATERIALS AND METHODS Swiss albino mice of either sex, weighing 20-30gm were used for the study. The animals were divided into 3 groups with 6 mice in each group: Control or Normal group received 0.5% methylcellulose in normal saline; Standard group received the drug tramadol HCl at 40mg/kg; and test group received drug AMN 082 at 5mg/kg. All the drugs were administered by intraperitoneal route. Hot plate test and Tail flick test were done to evaluate the analgesic effect of the drug. Reaction time for the end points in both the models were noted before drug administration at 0 min and after drug administration at 15, 30,60,90 and 120 min. Statistical analysis was done using One-Way-ANOVA followed by Tukeys post hoc test. p-value was considered significant at ≤ 0.05. RESULTS The group that received AMN082 showed significantly lesser reaction time compared to normal and standard groups in both the analgesia models. CONCLUSION The mGluR 7 stimulation by an agonist AMN082, did not show analgesic effect but induced hyperalgesia in response to thermal nociceptive stimuli.
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Affiliation(s)
- Shivaprakash G
- Associate Professor, Department of Pharmacology, Kasturba Medical College, Manipal University, Manipal, Karnataka, India
| | - Punya Suvarna
- Undergraduate Medical Student, Department of Pharmacology, Kasturba Medical College, Manipal University, Mangalore, Karnataka, India
| | - Sanjay Hadigal
- Postgraduate Student, Department of Pharmacology, Kasturba Medical College, Manipal University, Mangalore, Karnataka, India
| | - Priyanka Kamath
- Postgraduate Student, Department of Pharmacology, Kasturba Medical College, Manipal University, Mangalore, Karnataka, India
| | - Natesh Prabhu
- Postgraduate Student, Department of Pharmacology, Kasturba Medical College, Manipal University, Mangalore, Karnataka, India
| | - Ashok Shenoy K
- Professor and Head, Department of Pharmacology, Kasturba Medical College, Manipal University, Mangalore, Karnataka, India
| | - Pallavi LC
- Assistant Professor, Department of Physiology, Kasturba Medical College, Manipal University, Manipal, Karnataka, India
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20
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Pharmacology of metabotropic glutamate receptor allosteric modulators: structural basis and therapeutic potential for CNS disorders. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 115:61-121. [PMID: 23415092 DOI: 10.1016/b978-0-12-394587-7.00002-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The metabotropic glutamate receptors (mGlus) mediate a neuromodulatory role throughout the brain for the major excitatory neurotransmitter, glutamate. Seven of the eight mGlu subtypes are expressed within the CNS and are attractive targets for a variety of psychiatric and neurological disorders including anxiety, depression, schizophrenia, Parkinson's disease, and Fragile X syndrome. Allosteric modulation of these class C 7-transmembrane spanning receptors represents a novel approach to facilitate development of mGlu subtype-selective probes and therapeutics. Allosteric modulators that interact with sites topographically distinct from the endogenous ligand-binding site offer a number of advantages over their competitive counterparts. In particular for CNS therapeutics, allosteric modulators have the potential to maintain the spatial and temporal aspects of endogenous neurotransmission. The past 15 years have seen the discovery of numerous subtype-selective allosteric modulators for the majority of the mGlu family members, including positive, negative, and neutral allosteric modulators, with a number of mGlu allosteric modulators now in clinical trials.
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21
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Li JY, Wang X, Ji PT, Li XF, Guan GH, Jiang XS, Zhou GS, Hua F, Wang N. Peripheral nerve injury decreases the expression of metabolic glutamate receptor 7 in dorsal root ganglion neurons. Neurosci Lett 2012; 531:52-6. [PMID: 23085525 DOI: 10.1016/j.neulet.2012.10.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 10/09/2012] [Indexed: 01/08/2023]
Abstract
Group II and III metabolic glutamate receptors (mGluRs) are responsible for the glutamate-mediated postsynaptic excitation of neurons. Previous pharmacological evidences show that activation of mGluR7 could inhibit nociceptive reception. However, the distribution and expression patterns of mGluR7 after peripheral injury remain unclear. Herein we found that mGluR7 was expressed in the rat peptidergic dorsal root ganglion (DRG) neurons and large neurons, but rarely in isolectin B4 positive neurons. Sciatic nerve ligation experiment showed that mGluR7 was anterogradely transported from cell body to the peripheral site. Furthermore, after peripheral nerve injury, mGluR7 expression was down-regulated in both peptidergic and large DRG neurons. Our work suggests that mGluR7 might be involved in the regulation of pathological pain after peripheral nerve injury.
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Affiliation(s)
- Jian-You Li
- Orthopedics Department, Huzhou Central Hospital, 198 Hongqi Road, Huzhou 313000, People's Republic of China
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22
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Montana MC, Gereau RW. Metabotropic glutamate receptors as targets for analgesia: antagonism, activation, and allosteric modulation. Curr Pharm Biotechnol 2012; 12:1681-8. [PMID: 21466446 DOI: 10.2174/138920111798357438] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Accepted: 08/20/2010] [Indexed: 12/20/2022]
Abstract
The metabotropic glutamate receptors (mGluRs) are expressed pre- and post-synaptically throughout the nervous system where they serve as modulators of synaptic transmission and neuronal excitability. Activation of mGluRs can be pro- or anti-nociceptive, depending on their anatomic location and the signaling cascades to which they couple. Antagonists of Group I mGluRs and agonists of Group II and III mGluRs have shown therapeutic promise in animal pain models. This article reviews the potential therapeutic utility of several agents that act predominantly via mGluRs, specifically focusing on their analgesic efficacy and discussing possible off-target effects. Glutamate, the primary excitatory neurotransmitter in the vertebrate nervous system, mediates its effects via activation of two main classes of receptors: ligand-gated ion channels known as ionotropic receptors and G-protein coupled metabotropic receptors. Antagonists of ionotropic glutamate receptors, such as ketamine, have robust analgesic properties; however, their analgesic utility is limited to monitored clinical settings due to the potential for psychomimetic effects.
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Affiliation(s)
- Michael C Montana
- Washington University Pain Center, Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
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23
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Li X, Xi ZX, Markou A. Metabotropic glutamate 7 (mGlu7) receptor: a target for medication development for the treatment of cocaine dependence. Neuropharmacology 2012; 66:12-23. [PMID: 22546614 DOI: 10.1016/j.neuropharm.2012.04.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Revised: 03/21/2012] [Accepted: 04/11/2012] [Indexed: 11/19/2022]
Abstract
Brain glutamate has been shown to play an important role in reinstatement to drug seeking, a behavior considered to be of relevance to relapse to drug taking in humans. Therefore, glutamate receptors, in particular metabotropic glutamate (mGlu) receptors, have become important targets for medication development for the treatment of drug dependence. In this review article, we focus on the mGlu7 receptor subtype, and discuss recent findings with AMN082, a selective mGlu7 receptor allosteric agonist, in animal models with relevance to drug dependence. Systemic or local administration of AMN082 into the nucleus accumbens (NAc), a critical brain region involved in reward and drug dependence processes, inhibited the reinforcing and motivational effects of cocaine, heroin and ethanol, as assessed by the intravenous drug self-administration procedure. In addition, AMN082 inhibited the reward-enhancing effects induced by cocaine, as assessed in the intracranial self-stimulation procedure, and cocaine- or cue-induced reinstatement of drug-seeking behavior. In vivo microdialysis studies indicated that systemic or intra-NAc administration of AMN082 significantly decreased extracellular γ-aminobutyric acid (GABA) and elevated extracellular glutamate, but had no effect on extracellular dopamine in the NAc, suggesting that a non-dopaminergic mechanism underlies the effects of AMN082 on the actions of cocaine. Further, data indicated that AMN082-induced changes in glutamate were the net effect of two actions: one is the direct inhibition of glutamate release by activation of mGlu7 receptors on glutamatergic neurons; another is the indirect increases of glutamate release mediated by decreases in GABA transmission. These increases in extracellular glutamate functionally antagonized cocaine-induced inhibition of NAc-ventral pallidum GABAergic neurotransmission, and therefore, the rewarding effects of cocaine. In addition, elevated extracellular glutamate activated presynaptic mGlu2/3 autoreceptors which in turn inhibited cocaine priming- or cue-induced enhancement of glutamate release and reinstatement of drug-seeking behavior. Taken together, these findings suggest that the mGlu7 receptor is an important target for medication development for the treatment of drug dependence. AMN082 or other mGlu7 receptor allosteric agonists may have potential as novel pharmacotherapies for cocaine addiction. This article is part of a Special Issue entitled 'Metabotropic Glutamate Receptors'.
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Affiliation(s)
- Xia Li
- Department of Psychiatry, M/C 0603, School of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0603, USA.
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Chiechio S, Nicoletti F. Metabotropic glutamate receptors and the control of chronic pain. Curr Opin Pharmacol 2011; 12:28-34. [PMID: 22040745 DOI: 10.1016/j.coph.2011.10.010] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 10/10/2011] [Accepted: 10/10/2011] [Indexed: 01/13/2023]
Abstract
Over the past two decades metabotropic glutamate (mGlu) receptor ligands have been investigated for their potential therapeutic effects in different disorders of the central nervous system (CNS), including anxiety, depression, schizophrenia, and neurodegenerative diseases. In addition, it has been widely demonstrated that mGlu receptors are able to modulate pain transmission both in inflammatory and neuropathic pain models. A large number of preclinical studies combining the use of selective ligands with the knockout strategy have revealed more details about the role of the different mGlu receptor subtypes in the modulation of pain information. This review will address the role of mGlu receptors in pain sensitivity focusing on different strategies to achieve pain control by targeting specific mGlu receptor subtypes. Specifically, pharmacological interventions aimed at inhibiting group I mGlu receptor-mediated signaling and/or potentiating groups II and III mGlu receptor signaling together with an epigenetic approach leading to an increased expression of mGlu2 receptors will be discussed.
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25
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Sukoff Rizzo SJ, Leonard SK, Gilbert A, Dollings P, Smith DL, Zhang MY, Di L, Platt BJ, Neal S, Dwyer JM, Bender CN, Zhang J, Lock T, Kowal D, Kramer A, Randall A, Huselton C, Vishwanathan K, Tse SY, Butera J, Ring RH, Rosenzweig-Lipson S, Hughes ZA, Dunlop J. The metabotropic glutamate receptor 7 allosteric modulator AMN082: a monoaminergic agent in disguise? J Pharmacol Exp Ther 2011; 338:345-52. [PMID: 21508084 DOI: 10.1124/jpet.110.177378] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Metabotropic glutamate receptor 7 (mGluR7) remains the most elusive of the eight known mGluRs primarily because of the limited availability of tool compounds to interrogate its potential therapeutic utility. The discovery of N,N'-dibenzhydrylethane-1,2-diamine dihydrochloride (AMN082) as the first orally active, brain-penetrable, mGluR7-selective allosteric agonist by Mitsukawa and colleagues (Proc Natl Acad Sci USA 102:18712-18717, 2005) provides a means to investigate this receptor system directly. AMN082 demonstrates mGluR7 agonist activity in vitro and interestingly has a behavioral profile that supports utility across a broad spectrum of psychiatric disorders including anxiety and depression. The present studies were conducted to extend the in vitro and in vivo characterization of AMN082 by evaluating its pharmacokinetic and metabolite profile. Profiling of AMN082 in rat liver microsomes revealed rapid metabolism (t(1/2) < 1 min) to a major metabolite, N-benzhydrylethane-1,2-diamine (Met-1). In vitro selectivity profiling of Met-1 demonstrated physiologically relevant transporter binding affinity at serotonin transporter (SERT), dopamine transporter (DAT), and norepinephrine transporter (NET) (323, 3020, and 3410 nM, respectively); whereas the parent compound AMN082 had appreciable affinity at NET (1385 nM). AMN082 produced antidepressant-like activity and receptor occupancy at SERT up to 4 h postdose, a time point at which AMN082 is significantly reduced in brain and plasma while the concentration of Met-1 continues to increase in brain. Acute Met-1 administration produced antidepressant-like activity as would be expected from its in vitro profile as a mixed SERT, NET, DAT inhibitor. Taken together, these data suggest that the reported in vivo actions of AMN082 should be interpreted with caution, because they may involve other mechanisms in addition to mGluR7.
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Affiliation(s)
- Stacey J Sukoff Rizzo
- Pfizer Global Research and Development, Groton Laboratories, Groton, Connecticut 06340, USA.
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26
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Urwyler S. Allosteric modulation of family C G-protein-coupled receptors: from molecular insights to therapeutic perspectives. Pharmacol Rev 2011; 63:59-126. [PMID: 21228259 DOI: 10.1124/pr.109.002501] [Citation(s) in RCA: 164] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Allosteric receptor modulation is an attractive concept in drug targeting because it offers important potential advantages over conventional orthosteric agonism or antagonism. Allosteric ligands modulate receptor function by binding to a site distinct from the recognition site for the endogenous agonist. They often have no effect on their own and therefore act only in conjunction with physiological receptor activation. This article reviews the current status of allosteric modulation at family C G-protein coupled receptors in the light of their specific structural features on the one hand and current concepts in receptor theory on the other hand. Family C G-protein-coupled receptors are characterized by a large extracellular domain containing the orthosteric agonist binding site known as the "venus flytrap module" because of its bilobal structure and the dynamics of its activation mechanism. Mutational analysis and chimeric constructs have revealed that allosteric modulators of the calcium-sensing, metabotropic glutamate and GABA(B) receptors bind to the seven transmembrane domain, through which they modify signal transduction after receptor activation. This is in contrast to taste-enhancing molecules, which bind to different parts of sweet and umami receptors. The complexity of interactions between orthosteric and allosteric ligands is revealed by a number of adequate biochemical and electrophysiological assay systems. Many allosteric family C GPCR modulators show in vivo efficacy in behavioral models for a variety of clinical indications. The positive allosteric calcium sensing receptor modulator cinacalcet is the first drug of this type to enter the market and therefore provides proof of principle in humans.
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Affiliation(s)
- Stephan Urwyler
- Department of Chemistry and Biochemistry, University of Berne, P/A Weissensteinweg 3, CH-3303 Jegenstorf, Berne, Switzerland.
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Liu XJ, Salter MW. Glutamate receptor phosphorylation and trafficking in pain plasticity in spinal cord dorsal horn. Eur J Neurosci 2010; 32:278-89. [PMID: 20629726 DOI: 10.1111/j.1460-9568.2010.07351.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Glutamate is the major excitatory neurotransmitter in the central nervous system. Considerable evidence suggests that both ionotropic and metabotropic glutamate receptors are involved in pain hypersensitivity. However, glutamate receptor-based therapies are limited by side-effects because the activities of glutamate receptors are essential for many important physiological functions. Here, we review recent key findings in molecular and cellular mechanisms of glutamate receptor regulation and their roles in triggering and sustaining pain hypersensitivity. Targeting these molecular mechanisms could form the basis for new therapeutic strategies for the treatment of chronic pain.
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Affiliation(s)
- Xue Jun Liu
- Program in Neurosciences & Mental Health, the Hospital for Sick Children, Toronto, ON, Canada
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