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Zaremba M, Serafin P, Kleczkowska P. Antipsychotic Drugs Efficacy in Dextromethorphan-Induced Psychosis. Biomedicines 2023; 11:biomedicines11010123. [PMID: 36672631 PMCID: PMC9855940 DOI: 10.3390/biomedicines11010123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 12/28/2022] [Accepted: 12/29/2022] [Indexed: 01/06/2023] Open
Abstract
Psychosis is known as a broad term of symptoms that cause serious disorganization of behavior, thinking, and perception of reality. One of the medicines that recently gained much attention in terms of its psychotic potential is dextromethorphan (DXM). DXM, a widely used antitussive drug, is a commonly abused drug because of its euphoric, hallucinogenic, and dissociative properties. To date, DXM is a legally marketed cough suppressant that is neither a controlled substance nor a regulated chemical under the Controlled Substances Act. The management of DXM-related psychosis is dependent on the type of psychotic symptoms. Atypical neuroleptics (i.e., olanzapine, risperidone, quetiapine) and typical haloperidol have been used in symptomatic treatment due to their efficacy, especially in positive symptoms (hallucinations and delusions). These agents are also recognized as the preferred option in the symptomatic treatment of DXM-related psychosis due to their better efficacy and safety profile than typical haloperidol in the short-term course. The focus of the present review concerns the current stage of knowledge about DXM psychotic potency as well as the management of DXM-related psychoses with a special emphasis on atypical antipsychotic drugs (i.e., olanzapine, risperidone, quetiapine, and haloperidol).
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Affiliation(s)
- Malgorzata Zaremba
- Military Institute of Hygiene and Epidemiology, 01-163 Warsaw, Poland
- Department of Experimental and Clinical Pharmacology, Centre for Preclinical Research (CBP), Medical University of Warsaw, 02-097 Warsaw, Poland
| | - Pawel Serafin
- Military Institute of Hygiene and Epidemiology, 01-163 Warsaw, Poland
| | - Patrycja Kleczkowska
- Military Institute of Hygiene and Epidemiology, 01-163 Warsaw, Poland
- Maria Sklodowska-Curie, Medical Academy in Warsaw, Solidarnosci 12 Str., 03-411 Warsaw, Poland
- Correspondence: ; Tel.: +48-690-888-774
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Gale JR, Kosobucki GJ, Hartnett-Scott KA, Aizenman E. Imprecision in Precision Medicine: Differential Response of a Disease-Linked GluN2A Mutant to NMDA Channel Blockers. Front Pharmacol 2021; 12:773455. [PMID: 34776984 PMCID: PMC8581401 DOI: 10.3389/fphar.2021.773455] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 10/13/2021] [Indexed: 11/13/2022] Open
Abstract
Mutations in N-methyl-d-aspartate receptors (NMDAR) subunits have been implicated in a growing number of human neurodevelopmental disorders. Previously, a de novo mutation in GRIN2A, encoding the GluN2A subunit, was identified in a patient with severe epilepsy and developmental delay. This missense mutation, which leads to GluN2A-P552R, produces significant dendrotoxicity in transfected rodent cortical neurons, as evidenced by pronounced dendritic blebbing. This injurious process can be prevented by treatment with the NMDA antagonist memantine. Given the increasing use of FDA approved NMDA antagonists to treat patients with GRIN mutations, who may have seizures refractory to traditional anti-epileptic drugs, we investigated whether additional NMDA antagonists were effective in attenuating neurotoxicity associated with GluN2A-P552R expression. Intriguingly, we found that while treatment with memantine can effectively block GluN2A-P552R-mediated dendrotoxicity, treatment with ketamine does not, despite the fact that both drugs work as open NMDAR channel blockers. Interestingly, we found that neurons expressing GluN2A-P552R were more vulnerable to an excitotoxic insult-an effect that, in this case, could be equally rescued by both memantine and ketamine. These findings suggest that GluN2A-P552R induced dendrotoxicity and increased vulnerability to excitotoxic stress are mediated through two distinct mechanisms. The differences between memantine and ketamine in halting GluN2A-P552R dendrotoxicity could not be explained by NMDA antagonist induced changes in MAP or Src kinase activation, previously shown to participate in NMDA-induced excitotoxicity. Our findings strongly suggest that not all NMDA antagonists may be of equal clinical utility in treating GRIN2A-mediated neurological disorders, despite a shared mechanism of action.
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Affiliation(s)
- Jenna R Gale
- Department of Neurobiology and Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Gabrielle J Kosobucki
- Department of Neurobiology and Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Karen A Hartnett-Scott
- Department of Neurobiology and Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Elias Aizenman
- Department of Neurobiology and Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
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Psychotropic and Neuroreceptor Effects of Cyclopropylglycine Upon Intranasal Administration. Pharm Chem J 2021. [DOI: 10.1007/s11094-021-02445-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Vasileva EV, Kondrakhin EA, Abdullina AA, Salimov RM, Kovalev GI. Predominance of Nootropic or Anxiolytic Effects of Selank, Semax, and Noopept Peptides Depending on the Route of Administration to BALB/c and С57BL/6 Mice. NEUROCHEM J+ 2020. [DOI: 10.1134/s1819712420030113] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Kovalev GI, Salimov RM, Sukhorukova NA, Kondrakhin EA, Vasil’eva EV. Neuroreceptor Profile and Behavior of CD-1 Mice Subpopulations with Different Attention Stability. NEUROCHEM J+ 2020. [DOI: 10.1134/s1819712420010146] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Abdullina AA, Vasileva EV, Kondrakhin EA, Kovalev GI. The Involvement of the Serotonin, Glutamate, and GABA Receptors in the Manifestation of the Antidepressant-Like Effect of Cycloprolylglycine. NEUROCHEM J+ 2019. [DOI: 10.1134/s1819712419030024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Marwick KFM, Skehel PA, Hardingham GE, Wyllie DJA. The human NMDA receptor GluN2A N615K variant influences channel blocker potency. Pharmacol Res Perspect 2019; 7:e00495. [PMID: 31249692 PMCID: PMC6584472 DOI: 10.1002/prp2.495] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 05/06/2019] [Accepted: 05/19/2019] [Indexed: 01/10/2023] Open
Abstract
N-methyl-D-aspartate (NMDA) receptors are glutamate receptors with key roles in synaptic plasticity, due in part to their Mg2+ mediated voltage-dependence. A large number of genetic variants affecting NMDA receptor subunits have been found in people with a range of neurodevelopmental disorders, including GluN2AN615K (GRIN2AC1845A) in two unrelated individuals with severe epileptic encephalopathy. This missense variant substitutes a lysine in place of an asparagine known to be important for blockade by Mg2+ and other small molecule channel blockers. We therefore measured the impact of GluN2AN615K on a range of NMDA receptor channel blockers using two-electrode voltage clamp recordings made in Xenopus oocytes. We found that GluN2AN615K resulted in block by Mg2+ 1 mmol/L being greatly reduced (89% vs 8%), block by memantine 10 μmol/L (76% vs 27%) and amantadine 100 μmol/L (45% vs 17%) being substantially reduced, block by ketamine 10 μmol/L being modestly reduced (79% vs 73%) and block by dextromethorphan 10 μmol/L being enhanced (45% vs 55%). Coapplying Mg2+ with memantine or amantadine did not reduce the GluN2AN615K block seen with either small molecule. In addition, we measured single-channel conductance of GluN2AN615K-containing NMDA receptors in outside-out patches pulled from Xenopus oocytes, finding a 4-fold reduction in conductance (58 vs 15 pS). In conclusion, the GluN2AN615K variant is associated with substantial changes to important physiological and pharmacological properties of the NMDA receptor. Our findings are consistent with GluN2AN615K having a disease-causing role, and inform potential therapeutic strategies.
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Affiliation(s)
- Katie F. M. Marwick
- Centre for Discovery Brain SciencesHugh Robson Building, University of EdinburghEdinburghUK
| | - Paul A. Skehel
- Centre for Discovery Brain SciencesHugh Robson Building, University of EdinburghEdinburghUK
| | - Giles E. Hardingham
- Centre for Discovery Brain SciencesHugh Robson Building, University of EdinburghEdinburghUK
- Simons Initiative for the Developing Brain, Hugh Robson BuildingUniversity of EdinburghEdinburghUK
- UK Dementia Research InstituteUniversity of EdinburghEdinburghUK
| | - David J. A. Wyllie
- Centre for Discovery Brain SciencesHugh Robson Building, University of EdinburghEdinburghUK
- Simons Initiative for the Developing Brain, Hugh Robson BuildingUniversity of EdinburghEdinburghUK
- Centre for Brain Development and RepairInstitute for Stem Cell Biology and Regenerative MedicineBangaloreIndia
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Metaxas A, van Berckel BNM, Klein PJ, Verbeek J, Nash EC, Kooijman EJM, Renjaän VA, Golla SSV, Boellaard R, Christiaans JAM, Windhorst AD, Leysen JE. Binding characterization of N-(2-chloro-5-thiomethylphenyl)-N'-(3-[ 3 H] 3 methoxy phenyl)-N'-methylguanidine ([ 3 H]GMOM), a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist. Pharmacol Res Perspect 2019; 7:e00458. [PMID: 30784206 PMCID: PMC6381215 DOI: 10.1002/prp2.458] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 12/01/2018] [Accepted: 12/06/2018] [Indexed: 01/18/2023] Open
Abstract
Labeled with carbon‐11, N‐(2‐chloro‐5‐thiomethylphenyl)‐N′‐(3‐methoxyphenyl)‐N′‐methylguanidine ([11C]GMOM) is currently the only positron emission tomography (PET) tracer that has shown selectivity for the ion‐channel site of N‐methyl‐D‐aspartate (NMDA) receptors in human imaging studies. The present study reports on the selectivity profile and in vitro binding properties of GMOM. The compound was screened on a panel of 80 targets, and labeled with tritium ([3H]GMOM). The binding properties of [3H]GMOM were compared to those of the reference ion‐channel ligand [3H](+)‐dizocilpine maleate ([3H]MK‐801), in a set of concentration‐response, homologous and heterologous inhibition, and association kinetics assays, performed with repeatedly washed rat forebrain preparations. GMOM was at least 70‐fold more selective for NMDA receptors compared to all other targets examined. In homologous inhibition and concentration‐response assays, the binding of [3H]GMOM was regulated by NMDA receptor agonists, albeit in a less prominent manner compared to [3H]MK‐801. Scatchard transformation of homologous inhibition data produced concave upward curves for [3H]GMOM and [3H]MK‐801. The radioligands showed bi‐exponential association kinetics in the presence of 100 μmol L−1l‐glutamate/30 μmol L−1 glycine. [3H]GMOM (3 nmol L−1 and 10 nmol L−1) was inhibited with dual affinity by (+)‐MK‐801, (R,S)‐ketamine and memantine, in both presence and absence of agonists. [3H]MK‐801 (2 nmol L−1) was inhibited in a monophasic manner by GMOM under baseline and combined agonist conditions, with an IC50 value of ~19 nmol L−1. The non‐linear Scatchard plots, biphasic inhibition by open channel blockers, and bi‐exponential kinetics of [3H]GMOM indicate a complex mechanism of interaction with the NMDA receptor ionophore. The implications for quantifying the PET signal of [11C]GMOM are discussed.
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Affiliation(s)
- Athanasios Metaxas
- Department of Radiology & Nuclear Medicine, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, the Netherlands
| | - Bart N M van Berckel
- Department of Radiology & Nuclear Medicine, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, the Netherlands
| | - Pieter J Klein
- Department of Radiology & Nuclear Medicine, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, the Netherlands
| | - Joost Verbeek
- Department of Radiology & Nuclear Medicine, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, the Netherlands
| | - Emily C Nash
- Department of Radiology & Nuclear Medicine, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, the Netherlands
| | - Esther J M Kooijman
- Department of Radiology & Nuclear Medicine, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, the Netherlands
| | - Véronique A Renjaän
- Department of Radiology & Nuclear Medicine, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, the Netherlands
| | - Sandeep S V Golla
- Department of Radiology & Nuclear Medicine, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, the Netherlands
| | - Ronald Boellaard
- Department of Radiology & Nuclear Medicine, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, the Netherlands
| | - Johannes A M Christiaans
- Department of Radiology & Nuclear Medicine, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, the Netherlands
| | - Albert D Windhorst
- Department of Radiology & Nuclear Medicine, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, the Netherlands
| | - Josée E Leysen
- Department of Radiology & Nuclear Medicine, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, the Netherlands
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Kovalev IG, Vasil’eva EV, Kondrakhin EA, Voronina TA, Kovalev GI. The role of glutamate and GABA receptors in the anticonvulsive effects of levetiracetam and a 4-phenylpirrolidone derivative (GIZh-290) in rats. NEUROCHEM J+ 2017. [DOI: 10.1134/s1819712417040055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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10
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Martinak B, Bolis RA, Black JR, Fargason RE, Birur B. Dextromethorphan in Cough Syrup: The Poor Man's Psychosis. PSYCHOPHARMACOLOGY BULLETIN 2017; 47:59-63. [PMID: 28936010 PMCID: PMC5601090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Dextromethorphan (3-methoxy-N-methylmorphinan), also known as "DXM" and "the poor man's PCP," is a synthetically produced drug that is available in more than 140 over-the-counter cough and cold preparations. Dextromethorphan (DXM) has overtaken codeine as the most widely used cough suppressant due to its availability, efficacy, and safety profile at directed doses. However, DXM is subject to abuse. When consumed at inappropriately high doses (over 1500 mg/day), DXM can induce a state of psychosis characterized by Phencyclidine (PCP)-like psychological symptoms, including delusions, hallucinations, and paranoia. We report a noteworthy case of severe dextromethorphan use disorder with dextromethorphan-induced psychotic disorder in a 40-year-old Caucasian female, whose symptoms remitted only following treatment with a combination of an antipsychotic and mood stabilizer. While some states have begun to limit the quantity of DXM sold or restrict sales to individuals over 18-years of age, there is currently no federal ban or restriction on DXM. Abuse of DXM, a readily available and typically inexpensive agent that is not detected on a standard urine drug screen, may be an under-recognized cause of substance-induced psychosis. It is imperative that clinicians are aware of the potential psychiatric sequelae of recreational DXM use.
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Affiliation(s)
- Bridgette Martinak
- Dr. Martinak, MD, PGY3 Psychiatry Resident, Department of Psychiatry and Behavioral Neurobiology, University of Alabama, Birmingham. Mr. Bolis, MS-4, Medical Student-4, University of Alabama at Birmingham, Birmingham. Mr. Black, MS-4, Medical Student-4, University of Alabama at Birmingham, Birmingham. Dr. Fargason, MD, Professor, Department of Psychiatry and Behavioral Neurobiology, University of Alabama, Birmingham. Dr. Birur, MD, Assistant Professor, Department of Psychiatry and Behavioral Neurobiology, University of Alabama, Birmingham
| | - Ramy A Bolis
- Dr. Martinak, MD, PGY3 Psychiatry Resident, Department of Psychiatry and Behavioral Neurobiology, University of Alabama, Birmingham. Mr. Bolis, MS-4, Medical Student-4, University of Alabama at Birmingham, Birmingham. Mr. Black, MS-4, Medical Student-4, University of Alabama at Birmingham, Birmingham. Dr. Fargason, MD, Professor, Department of Psychiatry and Behavioral Neurobiology, University of Alabama, Birmingham. Dr. Birur, MD, Assistant Professor, Department of Psychiatry and Behavioral Neurobiology, University of Alabama, Birmingham
| | - Jeffrey Ryne Black
- Dr. Martinak, MD, PGY3 Psychiatry Resident, Department of Psychiatry and Behavioral Neurobiology, University of Alabama, Birmingham. Mr. Bolis, MS-4, Medical Student-4, University of Alabama at Birmingham, Birmingham. Mr. Black, MS-4, Medical Student-4, University of Alabama at Birmingham, Birmingham. Dr. Fargason, MD, Professor, Department of Psychiatry and Behavioral Neurobiology, University of Alabama, Birmingham. Dr. Birur, MD, Assistant Professor, Department of Psychiatry and Behavioral Neurobiology, University of Alabama, Birmingham
| | - Rachel E Fargason
- Dr. Martinak, MD, PGY3 Psychiatry Resident, Department of Psychiatry and Behavioral Neurobiology, University of Alabama, Birmingham. Mr. Bolis, MS-4, Medical Student-4, University of Alabama at Birmingham, Birmingham. Mr. Black, MS-4, Medical Student-4, University of Alabama at Birmingham, Birmingham. Dr. Fargason, MD, Professor, Department of Psychiatry and Behavioral Neurobiology, University of Alabama, Birmingham. Dr. Birur, MD, Assistant Professor, Department of Psychiatry and Behavioral Neurobiology, University of Alabama, Birmingham
| | - Badari Birur
- Dr. Martinak, MD, PGY3 Psychiatry Resident, Department of Psychiatry and Behavioral Neurobiology, University of Alabama, Birmingham. Mr. Bolis, MS-4, Medical Student-4, University of Alabama at Birmingham, Birmingham. Mr. Black, MS-4, Medical Student-4, University of Alabama at Birmingham, Birmingham. Dr. Fargason, MD, Professor, Department of Psychiatry and Behavioral Neurobiology, University of Alabama, Birmingham. Dr. Birur, MD, Assistant Professor, Department of Psychiatry and Behavioral Neurobiology, University of Alabama, Birmingham
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Otter S, Lammert E. Exciting Times for Pancreatic Islets: Glutamate Signaling in Endocrine Cells. Trends Endocrinol Metab 2016; 27:177-188. [PMID: 26740469 DOI: 10.1016/j.tem.2015.12.004] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 12/11/2015] [Accepted: 12/14/2015] [Indexed: 01/14/2023]
Abstract
Glutamate represents a key excitatory neurotransmitter in the central nervous system, and also modulates the function and viability of endocrine cells in pancreatic islets. In insulin-secreting beta cells, glutamate acts as an intracellular messenger, and its transport into secretory granules promotes glucose- and incretin-stimulated insulin secretion. Mitochondrial degradation of glutamate also contributes to insulin release when glutamate dehydrogenase is allosterically activated. It also signals extracellularly via glutamate receptors (AMPA and NMDA receptors) to modulate glucagon, insulin and somatostatin secretion, and islet cell survival. Its degradation products, GABA and γ-hydroxybutyrate, are released and also influence islet cell behavior. Thus, islet glutamate receptors, such as the NMDA receptors, might serve as possible drug targets to develop new medications for adjunct treatment of diabetes.
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Affiliation(s)
- Silke Otter
- Institute of Metabolic Physiology, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany; Institute for Beta Cell Biology, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research, and German Center for Diabetes Research (DZD e.V.), Düsseldorf, Germany
| | - Eckhard Lammert
- Institute of Metabolic Physiology, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany; Institute for Beta Cell Biology, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research, and German Center for Diabetes Research (DZD e.V.), Düsseldorf, Germany.
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Timosaponin derivative YY-23 acts as a non-competitive NMDA receptor antagonist and exerts a rapid antidepressant-like effect in mice. Acta Pharmacol Sin 2016; 37:166-76. [PMID: 26687936 DOI: 10.1038/aps.2015.111] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 10/28/2015] [Indexed: 12/20/2022] Open
Abstract
AIM N-methyl-D-aspartic acid (NMDA) receptor modulators have shown promising results as potential antidepressant agents, whereas timosaponins extracted from the Chinese herb Rhizoma Anemarrhenae exhibit antidepressant activities. In the present study we examined whether YY-23, a modified metabolite of timosaponin B-III, could affect NMDA receptors in rat hippocampal neurons in vitro, and evaluated its antidepressant-like effects in stressed mice. METHODS NMDA-induced currents were recorded in acutely dissociated rat hippocampal CA1 neurons using a whole-cell recording technique. C57BL/6 mice were exposed to a 6-week chronic mild stress (CMS) or a 10-d chronic social defeat stress (CSDS). The stressed mice were treated with YY-23 (20 mg·kg(-1)·d(-1)) or a positive-control drug, fluoxetine (10 mg·kg(-1)·d(-1)) for 3 weeks. Behavioral assessments were carried out every week. RESULTS In acutely dissociated rat hippocampal CA1 neurons, YY-23 selectively and reversibly inhibited NMDA-induced currents with an EC50 value of 2.8 μmol/L. This inhibition of NMDA-induced currents by YY-23 was non-competitive, and had no features of voltage-dependency or use-dependency. Treatment of the stressed mice with YY-23 not only reversed CMS-induced deficiency of sucrose preference and immobility time, and CSDS-induced reduction of social interaction, but also had faster onset as compared to fluoxetine. CONCLUSION YY-23 is a novel non-competitive antagonist of NMDA receptors with promising rapid antidepressant-like effects in mouse models of CMS and CSDS depression.
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Pierson TM, Yuan H, Marsh ED, Fuentes-Fajardo K, Adams DR, Markello T, Golas G, Simeonov DR, Holloman C, Tankovic A, Karamchandani MM, Schreiber JM, Mullikin JC, Tifft CJ, Toro C, Boerkoel CF, Traynelis SF, Gahl WA. GRIN2A mutation and early-onset epileptic encephalopathy: personalized therapy with memantine. Ann Clin Transl Neurol 2014; 1:190-198. [PMID: 24839611 PMCID: PMC4019449 DOI: 10.1002/acn3.39] [Citation(s) in RCA: 192] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Objective Early-onset epileptic encephalopathies have been associated with de novo mutations of numerous ion channel genes. We employed techniques of modern translational medicine to identify a disease-causing mutation, analyze its altered behavior, and screen for therapeutic compounds to treat the proband. Methods Three modern translational medicine tools were utilized: (1) high-throughput sequencing technology to identify a novel de novo mutation; (2) in vitro expression and electrophysiology assays to confirm the variant protein's dysfunction; and (3) screening of existing drug libraries to identify potential therapeutic compounds. Results A de novo GRIN2A missense mutation (c.2434C>A; p.L812M) increased the charge transfer mediated by N-methyl-D-aspartate receptors (NMDAs) containing the mutant GluN2A-L812M subunit. In vitro analysis with NMDA receptor blockers indicated that GLuN2A-L812M-containing NMDARs retained their sensitivity to the use-dependent channel blocker memantine; while screening of a previously reported GRIN2A mutation (N615K) with these compounds produced contrasting results. Consistent with these data, adjunct memantine therapy reduced our proband's seizure burden. Interpretation This case exemplifies the potential for personalized genomics and therapeutics to be utilized for the early diagnosis and treatment of infantile-onset neurological disease.
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Affiliation(s)
- Tyler Mark Pierson
- NIH Undiagnosed Diseases Program, NIH Office of Rare Diseases Research and NHGRI, Bethesda, MD, USA ; Neurogenetics Branch, NINDS, NIH, Bethesda, MD, USA ; Department of Pediatrics and Neurology, and the Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Hongjie Yuan
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA, USA
| | - Eric D Marsh
- Division of Neurology, Children's Hospital of Philadelphia and Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Karin Fuentes-Fajardo
- NIH Undiagnosed Diseases Program, NIH Office of Rare Diseases Research and NHGRI, Bethesda, MD, USA
| | - David R Adams
- NIH Undiagnosed Diseases Program, NIH Office of Rare Diseases Research and NHGRI, Bethesda, MD, USA ; Medical Genetics Branch, NHGRI, NIH, Bethesda, MD, USA
| | - Thomas Markello
- NIH Undiagnosed Diseases Program, NIH Office of Rare Diseases Research and NHGRI, Bethesda, MD, USA ; Office of the Clinical Director, NHGRI, NIH, Bethesda, MD, USA
| | - Gretchen Golas
- NIH Undiagnosed Diseases Program, NIH Office of Rare Diseases Research and NHGRI, Bethesda, MD, USA ; Office of the Clinical Director, NHGRI, NIH, Bethesda, MD, USA
| | - Dimitre R Simeonov
- NIH Undiagnosed Diseases Program, NIH Office of Rare Diseases Research and NHGRI, Bethesda, MD, USA
| | - Conisha Holloman
- NIH Undiagnosed Diseases Program, NIH Office of Rare Diseases Research and NHGRI, Bethesda, MD, USA ; Office of the Clinical Director, NHGRI, NIH, Bethesda, MD, USA
| | - Anel Tankovic
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA, USA
| | | | | | | | | | - Cynthia J Tifft
- NIH Undiagnosed Diseases Program, NIH Office of Rare Diseases Research and NHGRI, Bethesda, MD, USA ; Division of Neurology, Children's Hospital of Philadelphia and Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Camilo Toro
- NIH Undiagnosed Diseases Program, NIH Office of Rare Diseases Research and NHGRI, Bethesda, MD, USA ; Division of Neurology, Children's Hospital of Philadelphia and Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Cornelius F Boerkoel
- NIH Undiagnosed Diseases Program, NIH Office of Rare Diseases Research and NHGRI, Bethesda, MD, USA ; Division of Neurology, Children's Hospital of Philadelphia and Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Stephen F Traynelis
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA, USA
| | - William A Gahl
- NIH Undiagnosed Diseases Program, NIH Office of Rare Diseases Research and NHGRI, Bethesda, MD, USA ; Division of Neurology, Children's Hospital of Philadelphia and Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
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Santangelo RM, Acker TM, Zimmerman SS, Katzman BM, Strong KL, Traynelis SF, Liotta DC. Novel NMDA receptor modulators: an update. Expert Opin Ther Pat 2012; 22:1337-52. [PMID: 23009122 DOI: 10.1517/13543776.2012.728587] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
INTRODUCTION The NMDA receptor is a ligand-gated ion channel that plays a critical role in higher level brain processes and has been implicated in a range of neurological and psychiatric conditions. Although initial studies for the use of NMDA receptor antagonists in neuroprotection were unsuccessful, more recently, NMDA receptor antagonists have shown clinical promise in other indications such as Alzheimer's disease, Parkinson's disease, pain and depression. Based on the clinical observations and more recent insights into receptor pharmacology, new modulatory approaches are beginning to emerge, with potential therapeutic benefit. AREAS COVERED The article covers the known pharmacology and important features regarding NMDA receptors and their function. A discussion of pre-clinical and clinical relevance is included, as well. The subsequent patent literature review highlights the current state of the art targeting the receptor since the last review in 2010. EXPERT OPINION The complex nature of the NMDA receptor structure and function is becoming better understood. As knowledge about this receptor increases, it opens up new opportunities for targeting the receptor for many therapeutic indications. New strategies and advances in older technologies will need to be further developed before clinical success can be achieved. First-in-class potentiators and subunit-selective agents form the basis for most new strategies, complemented by efforts to limit off-target liability and fine-tune on-target properties.
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Lauterbach EC. An extension of hypotheses regarding rapid-acting, treatment-refractory, and conventional antidepressant activity of dextromethorphan and dextrorphan. Med Hypotheses 2012; 78:693-702. [PMID: 22401777 DOI: 10.1016/j.mehy.2012.02.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 02/10/2012] [Indexed: 12/14/2022]
Abstract
It was previously hypothesized that dextromethorphan (DM) and dextrorphan (DX) may possess antidepressant properties, including rapid and conventional onsets of action and utility in treatment-refractory depression, based on pharmacodynamic similarities to ketamine. These similarities included sigma-1 (σ(1)) agonist and NMDA antagonist properties, calcium channel blockade, muscarinic binding, serotonin transporter (5HTT) inhibition, and μ receptor potentiation. Here, six specific hypotheses are developed in light of additional mechanisms and evidence. Comparable potencies to ketamine for DM and DX are detailed for σ(1) (DX>DM>ketamine), NMDA PCP site (DX>ketamine>DM), and muscarinic (DX>ketamine>>>>DM) receptors, 5HTT (DM>DX≫ketamine), and NMDA antagonist potentiation of μ receptor stimulation (DM>ketamine). Rapid acting antidepressant properties of DM include NMDA high-affinity site, NMDR-2A, and functional NMDR-2B receptor antagonism, σ(1) stimulation, putative mTOR activation (by σ(1) stimulation, μ potentiation, and 5HTT inhibition), putative AMPA receptor trafficking (by mTOR activation, PCP antagonism, σ(1) stimulation, μ potentiation, and 5HTT inhibition), and dendritogenesis, spinogenesis, synaptogenesis, and neuronal survival by NMDA antagonism and σ(1) and mTOR signaling. Those for dextrorphan include NMDA high-affinity site and NMDR-2A antagonism, σ(1) stimulation, putative mTOR activation (by σ(1) stimulation and ß adrenoreceptor stimulation), putative AMPA receptor trafficking (by mTOR activation, PCP antagonism, σ(1) stimulation, ß stimulation, and μ antagonism), and dendritogenesis, spinogenesis, synaptogenesis, and neuronal survival by NMDA antagonism and σ(1) and mTOR signaling. Conventional antidepressant properties for dextromethorphan and dextrorphan include 5HTT and norepinephrine transporter inhibition, σ(1) stimulation, NMDA and PCP antagonism, and possible serotonin 5HT1b/d receptor stimulation. Additional properties for dextromethorphan include possible presynaptic α(2) adrenoreceptor antagonism or postsynaptic α(2) stimulation and, for dextrorphan, ß stimulation and possible muscarinic and μ antagonism. Treatment-refractory depression properties include increased serotonin and norepinephrine availability, PCP, NMDR-2B, presynaptic alpha-2 antagonism, and the multiplicity of other antidepressant receptor mechanisms. Suggestions for clinical trials are provided for oral high-dose dextromethorphan and Nuedexta (dextromethorphan combined with quinidine to block metabolism to dextrorphan, thereby increasing dextromethorphan plasma concentrations). Suggestions include exclusionary criteria, oral dosing, observation periods, dose-response approaches, and safety and tolerability are considered. Although oral dextromethorphan may be somewhat more likely to show efficacy through complementary antidepressant mechanisms of dextrorphan, a clinical trial will be more logistically complex than one of Nuedexta due to high doses and plasma level variability. Clinical trials may increase our therapeutic armamentarium and our pharmacological understanding of treatment-refractory depression and antidepressant onset of action.
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Affiliation(s)
- Edward C Lauterbach
- Department of Psychiatry and Behavioral Sciences, Mercer University School of Medicine, 1550 College Street, Macon, GA 31201, United States.
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Givvimani S, Qipshidze N, Tyagi N, Mishra PK, Sen U, Tyagi SC. Synergism between arrhythmia and hyperhomo-cysteinemia in structural heart disease. INTERNATIONAL JOURNAL OF PHYSIOLOGY, PATHOPHYSIOLOGY AND PHARMACOLOGY 2011; 3:107-119. [PMID: 21760969 PMCID: PMC3134005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Accepted: 05/23/2011] [Indexed: 05/31/2023]
Abstract
Elevated levels of homocysteine (Hcy) known as hyperhomocysteinemia (HHcy) is associated with cardiac arrhythmia and sudden cardiac death (SCD). Hcy increases iNOS, activates matrix metalloproteinase (MMP), disrupts connexin-43 and increases collagen/elastin ratio. The disruption of connexin-43 and accumulation of collagen (fibrosis) interupt cardiac conduction and attenuate NO transport from endothelium to myocyte (E-M) causing E-M uncoupling. We hypothesize that Hcy increases mtNOS, metalloproteinase activity, disrupts connexin-43, exacerbates endothelial-myocyte uncoupling, and induces cardiac failure by activating NMDA-R1 in structural heart disease. Chronic volume overload heart failure was created by aorta-venacava (AV) fistula. HHcy was induced by adminstrering Hcy in drinking water. NMDA-R1 was blocked by dizocilpine (MK-801). EKG and M-mode Echocardiography was performed. The E-M coupling was determined in cardiac rings. LV mitochondria was isolated. Levels of NMDA-R1, peroxiredoxin, NOX4, and mtNOS were measured. The degradation of connexin-43, collagen and elastin was measured by Western blot analysis. Mouse cardiac endothelial cells were cultured with or without Hcy or MK-801. The results suggest systolic and diastolic heart failure in HHcy and AVF mice. The levels of connexin, collagen degradation and MMP-9 were increased. The elastin was decreased in HHcy and AVF hearts. The mitochondrial NOX4 increased and peroxiredoxin was decreased. The mtNOS activity was synergistically increased in HHcy, AVF and HHcy+AVF hearts. The cardiac contraction and endothelial dependent relaxation was attenutated in HHcy and AVF hearts. Interestingly, the treatment with MK-801 mitigated the contractile dysfunction. These studies delineated the mechanism of Hcy-dependent endothelial-myocyte uncoupling in cardiac arrhythmia and failure, and have therapeutic ramifications for sudden cardiac death.
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Affiliation(s)
- Srikanth Givvimani
- Department of Physiology and Biophysics, University of Louisville School of Medicine Louisville, Kentucky
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Traynelis SF, Wollmuth LP, McBain CJ, Menniti FS, Vance KM, Ogden KK, Hansen KB, Yuan H, Myers SJ, Dingledine R. Glutamate receptor ion channels: structure, regulation, and function. Pharmacol Rev 2010; 62:405-96. [PMID: 20716669 PMCID: PMC2964903 DOI: 10.1124/pr.109.002451] [Citation(s) in RCA: 2546] [Impact Index Per Article: 181.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The mammalian ionotropic glutamate receptor family encodes 18 gene products that coassemble to form ligand-gated ion channels containing an agonist recognition site, a transmembrane ion permeation pathway, and gating elements that couple agonist-induced conformational changes to the opening or closing of the permeation pore. Glutamate receptors mediate fast excitatory synaptic transmission in the central nervous system and are localized on neuronal and non-neuronal cells. These receptors regulate a broad spectrum of processes in the brain, spinal cord, retina, and peripheral nervous system. Glutamate receptors are postulated to play important roles in numerous neurological diseases and have attracted intense scrutiny. The description of glutamate receptor structure, including its transmembrane elements, reveals a complex assembly of multiple semiautonomous extracellular domains linked to a pore-forming element with striking resemblance to an inverted potassium channel. In this review we discuss International Union of Basic and Clinical Pharmacology glutamate receptor nomenclature, structure, assembly, accessory subunits, interacting proteins, gene expression and translation, post-translational modifications, agonist and antagonist pharmacology, allosteric modulation, mechanisms of gating and permeation, roles in normal physiological function, as well as the potential therapeutic use of pharmacological agents acting at glutamate receptors.
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Affiliation(s)
- Stephen F Traynelis
- Department of Pharmacology, Emory University School of Medicine, Rollins Research Center, 1510 Clifton Road, Atlanta, GA 30322-3090, USA.
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Cobos EJ, Entrena JM, Nieto FR, Cendán CM, Del Pozo E. Pharmacology and therapeutic potential of sigma(1) receptor ligands. Curr Neuropharmacol 2010; 6:344-66. [PMID: 19587856 PMCID: PMC2701284 DOI: 10.2174/157015908787386113] [Citation(s) in RCA: 287] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Revised: 07/18/2008] [Accepted: 07/09/2008] [Indexed: 11/22/2022] Open
Abstract
Sigma (σ) receptors, initially described as a subtype of opioid receptors, are now considered unique receptors. Pharmacological studies have distinguished two types of σ receptors, termed σ1 and σ2. Of these two subtypes, the σ1 receptor has been cloned in humans and rodents, and its amino acid sequence shows no homology with other mammalian proteins. Several psychoactive drugs show high to moderate affinity for σ1 receptors, including the antipsychotic haloperidol, the antidepressant drugs fluvoxamine and sertraline, and the psychostimulants cocaine and methamphetamine; in addition, the anticonvulsant drug phenytoin allosterically modulates σ1 receptors. Certain neurosteroids are known to interact with σ1 receptors, and have been proposed to be their endogenous ligands. These receptors are located in the plasma membrane and in subcellular membranes, particularly in the endoplasmic reticulum, where they play a modulatory role in intracellular Ca2+ signaling. Sigma1 receptors also play a modulatory role in the activity of some ion channels and in several neurotransmitter systems, mainly in glutamatergic neurotransmission. In accordance with their widespread modulatory role, σ1 receptor ligands have been proposed to be useful in several therapeutic fields such as amnesic and cognitive deficits, depression and anxiety, schizophrenia, analgesia, and against some effects of drugs of abuse (such as cocaine and methamphetamine). In this review we provide an overview of the present knowledge of σ1 receptors, focussing on σ1 ligand neuropharmacology and the role of σ1 receptors in behavioral animal studies, which have contributed greatly to the potential therapeutic applications of σ1 ligands.
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Affiliation(s)
- E J Cobos
- Department of Pharmacology and Institute of Neuroscience, Faculty of Medicine, University of Granada, Granada, Spain
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Zolotarev YA, Firsova YY, Abaimov A, Dadayan AK, Kosik VS, Novikov AV, Krasnov NV, Vaskovskii BV, Nazimov IV, Kovalev GI, Myasoedov NF. Ligands of glutamate and dopamine receptors evenly labeled with hydrogen isotopes. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2009; 35:323-33. [DOI: 10.1134/s1068162009030030] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Kaczor AA, Kijkowska-Murak UA, Kronbach C, Unverferth K, Matosiuk D. Modeling of glutamate GluR6 receptor and its interactions with novel noncompetitive antagonists. J Chem Inf Model 2009; 49:1094-104. [PMID: 19338341 DOI: 10.1021/ci900033m] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The study proposes the first complete model of an ionotropic glutamate receptor (GluR6). The model is in accordance with available experimental data from single-particle electron microscopy images and exhibits correct shape and dimensions and the appropriate symmetry: 2-fold in the N-terminal domain (NTD), ligand-binding domain (LBD), and external part of the transmembrane region, whereas it is 4-fold deeper in the channel. The methodology applied for GluR6 receptor model building was validated in the docking procedure of competitive and uncompetitive antagonists. The constructed model was used to study molecular interactions of novel noncompetitive GluR6 antagonists with their molecular target. A new binding site in the GluR6 receptor transduction domain has been identified. It is situated between two subunits in the receptor dimer. The following residues were recognized as crucial for interactions: Arg663A, Arg663B (M3-S2 linker), Ser809B (S2-M4 linker), and Phe553A (S1-M1 linker).
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Affiliation(s)
- Agnieszka A Kaczor
- Department of Synthesis and Chemical Technology of Pharmaceutical Substances, Faculty of Pharmacy, Medical University of Lublin, 6 Staszica Str., 20081 Lublin, Poland.
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Kalia LV, Kalia SK, Salter MW. NMDA receptors in clinical neurology: excitatory times ahead. Lancet Neurol 2008; 7:742-55. [PMID: 18635022 DOI: 10.1016/s1474-4422(08)70165-0] [Citation(s) in RCA: 279] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Since the N-methyl-D-aspartate receptor (NMDAR) subunits were cloned less than two decades ago, a substantial amount of research has been invested into understanding their physiological function in the healthy CNS. Research has also been directed at their pathological roles in various neurological diseases, including disorders resulting from acute excitotoxic insults (eg, ischaemic stroke, traumatic brain injury), diseases due to chronic neurodegeneration (eg, Alzheimer's, Parkinson's, and Huntington's diseases and amyotrophic lateral sclerosis), disorders arising from sensitisation of neurons (eg, epilepsy, neuropathic pain), and neurodevelopmental disorders associated with NMDAR hypofunction (eg, schizophrenia). Selective NMDAR antagonists have not produced positive results in clinical trials. However, there are other NMDAR-targeted therapies used in current practice that are effective for treating some neurological disorders. In this Review, we describe the evidence for the use of these therapies and provide an overview of drugs being investigated in clinical trials. We also discuss new NMDAR-targeted strategies in clinical neurology.
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Affiliation(s)
- Lorraine V Kalia
- Division of Neurology, Department of Medicine, University of Toronto, ON, Canada.
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Werling LL, Lauterbach EC, Calef U. Dextromethorphan as a Potential Neuroprotective Agent With Unique Mechanisms of Action. Neurologist 2007; 13:272-93. [PMID: 17848867 DOI: 10.1097/nrl.0b013e3180f60bd8] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
BACKGROUND Dextromethorphan (DM) is a widely-used antitussive. DM's complex central nervous system (CNS) pharmacology became of interest when it was discovered to be neuroprotective due to its low-affinity, uncompetitive N-methyl-D-aspartate (NMDA) receptor antagonism. REVIEW SUMMARY Mounting preclinical evidence has proven that DM has important neuroprotective properties in various CNS injury models, including focal and global ischemia, seizure, and traumatic brain injury paradigms. Many of these protective actions seem functionally related to its inhibitory effects on glutamate-induced neurotoxicity via NMDA receptor antagonist, sigma-1 receptor agonist, and voltage-gated calcium channel antagonist actions. DM's protection of dopamine neurons in parkinsonian models may be due to inhibition of neurodegenerative inflammatory responses. Clinical findings are limited, with preliminary evidence indicating that DM protects against neuronal damage. Negative findings seem to relate to attainment of inadequate DM brain concentrations. Small studies have shown some promise for treatment of perioperative brain injury, amyotrophic lateral sclerosis, and symptoms of methotrexate neurotoxicity. DM safety/tolerability trials in stroke, neurosurgery, and amyotrophic lateral sclerosis patients demonstrated a favorable safety profile. DM's limited clinical benefit is proposed to be associated with its rapid metabolism to dextrorphan, which restricts its central bioavailability and therapeutic utility. Systemic concentrations of DM can be increased via coadministration of low-dose quinidine (Q), which reversibly inhibits its first-pass elimination. Potential drug interactions with DM/Q are discussed. CONCLUSIONS Given the compelling preclinical evidence for neuroprotective properties of DM, initial clinical neuroprotective findings, and clinical demonstrations that the DM/Q combination is well tolerated, this strategy may hold promise for the treatment of various acute and degenerative neurologic disorders.
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Affiliation(s)
- Linda L Werling
- The Institute for Biomedical Sciences, The George Washington University Medical Center, Washington, DC, USA
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Abstract
Adjuvants are compounds which by themselves have undesirable side-effects or low potency but in combination with opioids allow a reduction of narcotic dosing for postoperative pain control. Adjuvants are needed for postoperative pain management due to side-effects of opioid analgesics, which hinder recovery, especially in the increasingly utilized ambulatory surgical procedures. NMDA antagonists have psychomimetic side-effects at high doses, but at moderate doses do not cause stereotypic behavior but allow reduction in opioid dose to obtain better pain control. Alpha-2 adrenergic agonists cause sedation, hypotension and bradycardia at moderate doses, but at low doses can be opioid sparing especially in spinal administration. Gabapentin-like compounds have low potency against acute pain, but in combination with opioids allow a reduction in opioid dose with improved analgesia. Corticosteroids may have only a limited role as adjuvants while acetylcholine esterase inhibitors may have too many side-effects. Newer adjuvants will be needed to reduce opioid dose and concomitant side-effects, even more as same day surgeries become more routine.
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Affiliation(s)
- Asokumar Buvanendran
- Department of Anesthesiology, 1653 W Congress Parkway, # 739, Rush University Medical Center, Chicago, IL 60612, USA.
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Dravid SM, Erreger K, Yuan H, Nicholson K, Le P, Lyuboslavsky P, Almonte A, Murray E, Mosely C, Barber J, French A, Balster R, Murray TF, Traynelis SF. Subunit-specific mechanisms and proton sensitivity of NMDA receptor channel block. J Physiol 2007; 581:107-28. [PMID: 17303642 PMCID: PMC2075223 DOI: 10.1113/jphysiol.2006.124958] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
We have compared the potencies of structurally distinct channel blockers at recombinant NR1/NR2A, NR1/NR2B, NR1/NR2C and NR1/NR2D receptors. The IC50 values varied with stereochemistry and subunit composition, suggesting that it may be possible to design subunit-selective channel blockers. For dizocilpine (MK-801), the differential potency of MK-801 stereoisomers determined at recombinant NMDA receptors was confirmed at native receptors in vitro and in vivo. Since the proton sensor is tightly linked both structurally and functionally to channel gating, we examined whether blocking molecules that interact in the channel pore with the gating machinery can differentially sense protonation of the receptor. Blockers capable of remaining trapped in the pore during agonist unbinding showed the strongest dependence on extracellular pH, appearing more potent at acidic pH values that promote channel closure. Determination of pK(a) values for channel blockers suggests that the ionization of ketamine but not of other blockers can influence its pH-dependent potency. Kinetic modelling and single channel studies suggest that the pH-dependent block of NR1/NR2A by (-)MK-801 but not (+)MK-801 reflects an increase in the MK-801 association rate even though protons reduce channel open probability and thus MK-801 access to its binding site. Allosteric modulators that alter pH sensitivity alter the potency of MK-801, supporting the interpretation that the pH sensitivity of MK-801 binding reflects the changes at the proton sensor rather than a secondary effect of pH. These data suggest a tight coupling between the proton sensor and the ion channel gate as well as unique subunit-specific mechanisms of channel block.
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Affiliation(s)
- Shashank M Dravid
- Department of Pharmacology, Emory University School of Medicine, Rollins Research Centre, 1510 Clifton Road, Atlanta, GA 30322-3090, USA.
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Yuan H, Erreger K, Dravid SM, Traynelis SF. Conserved Structural and Functional Control of N-Methyl-d-aspartate Receptor Gating by Transmembrane Domain M3. J Biol Chem 2005; 280:29708-16. [PMID: 15970596 DOI: 10.1074/jbc.m414215200] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The molecular events controlling glutamate receptor ion channel gating are complex. The movement of transmembrane domain M3 within N-methyl-d-aspartate (NMDA) receptor subunits has been suggested to be one structural determinant linking agonist binding to channel gating. Here we report that covalent modification of NR1-A652C or the analogous mutation in NR2A, -2B, -2C, or -2D by methanethiosulfonate ethylammonium (MT-SEA) occurs only in the presence of glutamate and glycine, and that modification potentiates recombinant NMDA receptor currents. The modified channels remain open even after removing glutamate and glycine from the external solution. The degree of potentiation depends on the identity of the NR2 subunit (NR2A < NR2B < NR2C,D) inversely correlating with previous measurements of channel open probability. MTSEA-induced modification of channels is associated with increased glutamate potency, increased mean single-channel open time, and slightly decreased channel conductance. Modified channels are insensitive to the competitive antagonists D-2-amino-5-phosphonovaleric acid (APV) and 7-Cl-kynurenic acid, as well as allosteric modulators of gating (extracellular protons and Zn(2+)). However, channels remain fully sensitive to Mg(2+) blockade and partially sensitive to pore block by (+)MK-801, (-)MK-801, ketamine, memantine, amantadine, and dextrorphan. The partial sensitivity to (+)MK-801 may reflect its ability to stimulate agonist unbinding from MT-SEA-modified receptors. In summary, these data suggest that the SYTANLAAF motif within M3 is a conserved and critical determinant of channel gating in all NMDA receptors.
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Affiliation(s)
- Hongjie Yuan
- Department of Pharmacology, Emory University School of Medicine, Rollins Research Center, Atlanta, Georgia 30322-3090, USA
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