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Ma M, Xu H, Ye L, Li C, Zhu H, Jiang W, Wang W, Yang H, Yang Y, Wang Y, Tian J. Synthesis and evaluation of neuroactive steroids with novel pharmacophore at C-21 let identify a compound with advantageous PK profile and higher EC 50 and E max as PAM on GABAA receptor. Eur J Med Chem 2024; 276:116602. [PMID: 38971049 DOI: 10.1016/j.ejmech.2024.116602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 06/03/2024] [Accepted: 06/13/2024] [Indexed: 07/08/2024]
Abstract
Zuranolone (SAGE-217) is a neuroactive steroid (γ-aminobutyric acid)A (GABAA) receptor positive allosteric modulator (PAM) as the first oral drug approved by the FDA in 2023, which is used to treat patients with postpartum depression (PPD). SAGE-217 has a "black box" warning with impairing ability to drive or engage in other potentially hazardous activities. In addition, SAGE-217 can cause CNS depressant effects such as somnolence and confusion, suicidal thoughts and behavior and embryo-fetal toxicity. Based on the structure-activity relationship (SAR) of SAGE-217, a total of 28 neuroactive steroids with novel pharmacophore at C-21 modulated SAGE-217 derivatives were designed and synthesized. The biological activities were evaluated by both synaptic α1β2γ2 GABAA receptor and extrasynaptic α4β3δ GABAA receptor cell assays. The optimal compound S28 exhibited much more potent potency and similar efficacy at extrasynaptic GABAA receptor than SAGE-217. Different from above, compound S28 exhibited similar potency and lower efficacy at synaptic GABAA receptor than SAGE-217, which were consistent with the analysis of molecular docking and dynamics simulation results. The appropriate lower efficacy at synaptic GABAA receptor of compound S28 might contribute to reduce the side effects of excessive sedation. Furthermore, compound S28 was demonstrated to have excellent in vivo pharmacokinetic (PK) parameters, robust in vivo pharmacodynamic (PD) effects and good safety profiles. Therefore, compound S28 represents a potentially promising treatment of PPD candidate that warrants further investigation.
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Affiliation(s)
- Mingxu Ma
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, 264005, China; State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China
| | - Hengwei Xu
- State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China
| | - Liang Ye
- State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China; School of Public Health and Management, Binzhou Medical University, Yantai, 256603, China
| | - Chunmei Li
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, 264005, China; State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China
| | - Haibo Zhu
- State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China; School of Public Health and Management, Binzhou Medical University, Yantai, 256603, China
| | - Wanglin Jiang
- State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China; School of Pharmacy, Binzhou Medical University, Yantai, 256603, China
| | - Wenyan Wang
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, 264005, China; State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China
| | - Huijie Yang
- State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China
| | - Yingjie Yang
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, 264005, China; State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China
| | - Yao Wang
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, 264005, China; State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China
| | - Jingwei Tian
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, 264005, China; State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China.
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2
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Chojnacka W, Teng J, Kim JJ, Jensen AA, Hibbs RE. Structural insights into GABA A receptor potentiation by Quaalude. Nat Commun 2024; 15:5244. [PMID: 38898000 PMCID: PMC11187190 DOI: 10.1038/s41467-024-49471-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Accepted: 05/31/2024] [Indexed: 06/21/2024] Open
Abstract
Methaqualone, a quinazolinone marketed commercially as Quaalude, is a central nervous system depressant that was used clinically as a sedative-hypnotic, then became a notorious recreational drug in the 1960s-80s. Due to its high abuse potential, medical use of methaqualone was eventually prohibited, yet it persists as a globally abused substance. Methaqualone principally targets GABAA receptors, which are the major inhibitory neurotransmitter-gated ion channels in the brain. The restricted status and limited accessibility of methaqualone have contributed to its pharmacology being understudied. Here, we use cryo-EM to localize the GABAA receptor binding sites of methaqualone and its more potent derivative, PPTQ, to the same intersubunit transmembrane sites targeted by the general anesthetics propofol and etomidate. Both methaqualone and PPTQ insert more deeply into subunit interfaces than the previously-characterized modulators. Binding of quinazolinones to this site results in widening of the extracellular half of the ion-conducting pore, following a trend among positive allosteric modulators in destabilizing the hydrophobic activation gate in the pore as a mechanism for receptor potentiation. These insights shed light on the underexplored pharmacology of quinazolinones and further elucidate the molecular mechanisms of allosteric GABAA receptor modulation through transmembrane binding sites.
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Affiliation(s)
- Weronika Chojnacka
- Biomedical Sciences Graduate Program, University of California San Diego, La Jolla, CA, USA
- Department of Neurobiology, University of California San Diego, La Jolla, CA, USA
| | - Jinfeng Teng
- Department of Neurobiology, University of California San Diego, La Jolla, CA, USA
| | - Jeong Joo Kim
- Protein Structure and Function, Loxo@Lilly, Louisville, CO, USA
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Ryan E Hibbs
- Department of Neurobiology, University of California San Diego, La Jolla, CA, USA.
- Department of Pharmacology, University of California San Diego, La Jolla, CA, USA.
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3
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Li X, Prudente AS, Prato V, Guo X, Hao H, Jones F, Figoli S, Mullen P, Wang Y, Tonello R, Lee SH, Shah S, Maffei B, Berta T, Du X, Gamper N. Peripheral gating of mechanosensation by glial diazepam binding inhibitor. J Clin Invest 2024; 134:e176227. [PMID: 38888973 PMCID: PMC11324294 DOI: 10.1172/jci176227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 06/13/2024] [Indexed: 06/20/2024] Open
Abstract
We report that diazepam binding inhibitor (DBI) is a glial messenger mediating crosstalk between satellite glial cells (SGCs) and sensory neurons in the dorsal root ganglion (DRG). DBI is highly expressed in SGCs of mice, rats, and humans, but not in sensory neurons or most other DRG-resident cells. Knockdown of DBI results in a robust mechanical hypersensitivity without major effects on other sensory modalities. In vivo overexpression of DBI in SGCs reduces sensitivity to mechanical stimulation and alleviates mechanical allodynia in neuropathic and inflammatory pain models. We further show that DBI acts as an unconventional agonist and positive allosteric modulator at the neuronal GABAA receptors, particularly strongly affecting those with a high-affinity benzodiazepine binding site. Such receptors are selectively expressed by a subpopulation of mechanosensitive DRG neurons, and these are also more enwrapped with DBI-expressing glia, as compared with other DRG neurons, suggesting a mechanism for a specific effect of DBI on mechanosensation. These findings identified a communication mechanism between peripheral neurons and SGCs. This communication modulates pain signaling and can be targeted therapeutically.
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Affiliation(s)
- Xinmeng Li
- Department of Pharmacology; The Key Laboratory of Neural and Vascular Biology, Ministry of Education; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Arthur Silveira Prudente
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, Ohio, USA
| | - Vincenzo Prato
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Xianchuan Guo
- Department of Pharmacology; The Key Laboratory of Neural and Vascular Biology, Ministry of Education; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Han Hao
- Department of Pharmacology; The Key Laboratory of Neural and Vascular Biology, Ministry of Education; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Frederick Jones
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
- Department of Life Sciences, Manchester Metropolitan University, Manchester, United Kingdom
| | - Sofia Figoli
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Pierce Mullen
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Yujin Wang
- Department of Pharmacology; The Key Laboratory of Neural and Vascular Biology, Ministry of Education; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Raquel Tonello
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, Ohio, USA
| | - Sang Hoon Lee
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, Ohio, USA
| | - Shihab Shah
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Benito Maffei
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Temugin Berta
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, Ohio, USA
| | - Xiaona Du
- Department of Pharmacology; The Key Laboratory of Neural and Vascular Biology, Ministry of Education; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Nikita Gamper
- Department of Pharmacology; The Key Laboratory of Neural and Vascular Biology, Ministry of Education; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei, China
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
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Wu J, Zhao M, Jin YC, Li M, Yu KX, Yu HB. Schisandrin B, a dual positive allosteric modulator of GABA A and glycine receptors, alleviates seizures in multiple mouse models. Acta Pharmacol Sin 2024; 45:465-479. [PMID: 38017298 PMCID: PMC10834591 DOI: 10.1038/s41401-023-01195-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 11/09/2023] [Indexed: 11/30/2023] Open
Abstract
Epilepsy is a prevalent and severe neurological disorder and approximately 30% of patients are resistant to existing medications. It is of utmost importance to develop alternative therapies to treat epilepsy. Schisandrin B (SchB) is a major bioactive constituent of Schisandra chinensis (Turcz.) Baill and has multiple neuroprotective effects, sedative and hypnotic activities. In this study, we investigated the antiseizure effect of SchB in various mouse models of seizure and explored the underlying mechanisms. Pentylenetetrazole (PTZ), strychnine (STR), and pilocarpine-induced mouse seizure models were established. We showed that injection of SchB (10, 30, 60 mg/kg, i.p.) dose-dependently delayed the onset of generalized tonic-clonic seizures (GTCS), reduced the incidence of GTCS and mortality in PTZ and STR models. Meanwhile, injection of SchB (30 mg/kg, i.p.) exhibited therapeutic potential in pilocarpine-induced status epilepticus model, which was considered as a drug-resistant model. In whole-cell recording from CHO/HEK-239 cells stably expressing recombinant human GABAA receptors (GABAARs) and glycine receptors (GlyRs) and cultured hippocampal neurons, co-application of SchB dose-dependently enhanced GABA or glycine-induced current with EC50 values at around 5 μM, and application of SchB (10 μM) alone did not activate the channels in the absence of GABA or glycine. Furthermore, SchB (10 μM) eliminated both PTZ-induced inhibition on GABA-induced current (IGABA) and strychnine (STR)-induced inhibition on glycine-induced current (Iglycine). Moreover, SchB (10 μM) efficiently rescued the impaired GABAARs associated with genetic epilepsies. In addition, the homologous mutants in both GlyRs-α1(S267Q) and GABAARs-α1(S297Q)β2(N289S)γ2L receptors by site-directed mutagenesis tests abolished SchB-induced potentiation of IGABA and Iglycine. In conclusion, we have identified SchB as a natural positive allosteric modulator of GABAARs and GlyRs, supporting its potential as alternative therapies for epilepsy.
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Affiliation(s)
- Jun Wu
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Miao Zhao
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Yu-Chen Jin
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Min Li
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Ke-Xin Yu
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Hai-Bo Yu
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China.
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5
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Li X, Prudente AS, Prato V, Guo X, Hao H, Jones F, Figoli S, Mullen P, Wang Y, Tonnello R, Lee SH, Shah S, Maffei B, Berta T, Du X, Gamper N. Peripheral gating of pain by glial endozepine. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.20.567848. [PMID: 38045227 PMCID: PMC10690183 DOI: 10.1101/2023.11.20.567848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
We report that diazepam binding inhibitor (DBI) is a glial messenger mediating satellite glia-sensory neuron crosstalk in the dorsal root ganglion (DRG). DBI is highly and specifically expressed in satellite glia cells (SGCs) of mice, rat and human, but not in sensory neurons or other DRG-resident cells. Knockdown of DBI results in a robust mechanical hypersensitivity without significant effects on other sensory modalities. In vivo overexpression of DBI in SGCs reduces sensitivity to mechanical stimulation and alleviates mechanical allodynia in neuropathic and inflammatory pain models. We further show that DBI acts as a partial agonist and positive allosteric modulator at the neuronal GABAA receptors, particularly strongly effecting those with a high-affinity benzodiazepine binding site. Such receptors are selectively expressed by a subpopulation of mechanosensitive DRG neurons and these are also more enwrapped with DBI-expressing glia, as compared to other DRG neurons, suggesting a mechanism for specific effect of DBI on mechanosensation. These findings identified a new, peripheral neuron-glia communication mechanism modulating pain signalling, which can be targeted therapeutically.
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Affiliation(s)
- Xinmeng Li
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Arthur Silveira Prudente
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, OH, USA
| | - Vincenzo Prato
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Xianchuan Guo
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Han Hao
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Frederick Jones
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, UK
- Department of Life Sciences, Manchester Metropolitan University, Manchester, UK
| | - Sofia Figoli
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Pierce Mullen
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Yujin Wang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Raquel Tonnello
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, OH, USA
| | - Sang Hoon Lee
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, OH, USA
| | - Shihab Shah
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Benito Maffei
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Temugin Berta
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, OH, USA
| | - Xiaona Du
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Nikita Gamper
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, UK
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6
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Chaudhuri T, Hosur MV. Molecular modelling reveals how abundance of α4 sub-type in synaptic GABAR A receptor can lead to refractoriness toward GABA and BZ-type drugs. J Biomol Struct Dyn 2023:1-8. [PMID: 37948195 DOI: 10.1080/07391102.2023.2277858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 10/25/2023] [Indexed: 11/12/2023]
Abstract
Epilepsy is a complex neurological disorder with genetic and acquired causes, and the drugs presently used to treat epilepsy are not effective in about 30% of the cases. Identification of the molecular mechanisms of resistance will help in the development of newer molecules for treatment. Recent clinical data indicate increased expression of α4- and γ2-containing synaptic GABARA receptors in patients of focal cortical dysplasia (FCD), which is associated with refractory epilepsy pathology. We have investigated, by molecular modelling and docking, the structure and ligand-binding efficiency of the α4-containing hetero-pentameric synaptic GABARA receptor. Though the overall conformation is similar to that of the α1-containing receptor, local conformational changes are seen due to differences between aligned α1 and α4 sub-type residues. The overlaps ALA209(α1)/PRO215(α4) and PHE73(α1)/TYR79(α4) have together caused conformational changes in ARG100(α4) (aligned with ARG94 in α1) thereby affecting key hydrogen bonding interactions with the inhibitory neurotransmitter GABA. This may influence the nature of seizures as strength of GABA-binding is known to affect the nature of Inhibitory Post-Synaptic Currents (IPSCs) from GABAergic neurons. The residue ARG135 (α4) aligns with the residue HIS129 (α1) in the benzodiazapine binding pocket. Molecular modelling also shows that a steric clash between benzodiazapine-type (BZ-type) drugs and ARG135 would reduce the binding of BZ-type drugs to α4-containing receptor. These two findings rationalize the observed association between over-expression of α4-containing synaptic GABARA receptors and refractory epilepsy pathology in FCD. The accurate three-dimensional geometry of the receptor-drug complex made available by these modelling studies will help in designing effective drugs.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Tanusree Chaudhuri
- Department of Natural Sciences and Engineering, National Institute of Advanced Studies, Bangalore, India
| | - M V Hosur
- Department of Natural Sciences and Engineering, National Institute of Advanced Studies, Bangalore, India
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7
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Lorenz-Guertin JM, Povysheva N, Chapman CA, MacDonald ML, Fazzari M, Nigam A, Nuwer JL, Das S, Brady ML, Vajn K, Bambino MJ, Weintraub ST, Johnson JW, Jacob TC. Inhibitory and excitatory synaptic neuroadaptations in the diazepam tolerant brain. Neurobiol Dis 2023; 185:106248. [PMID: 37536384 PMCID: PMC10578451 DOI: 10.1016/j.nbd.2023.106248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 07/20/2023] [Accepted: 07/31/2023] [Indexed: 08/05/2023] Open
Abstract
Benzodiazepine (BZ) drugs treat seizures, anxiety, insomnia, and alcohol withdrawal by potentiating γ2 subunit containing GABA type A receptors (GABAARs). BZ clinical use is hampered by tolerance and withdrawal symptoms including heightened seizure susceptibility, panic, and sleep disturbances. Here, we investigated inhibitory GABAergic and excitatory glutamatergic plasticity in mice tolerant to benzodiazepine sedation. Repeated diazepam (DZP) treatment diminished sedative effects and decreased DZP potentiation of GABAAR synaptic currents without impacting overall synaptic inhibition. While DZP did not alter γ2-GABAAR subunit composition, there was a redistribution of extrasynaptic GABAARs to synapses, resulting in higher levels of synaptic BZ-insensitive α4-containing GABAARs and a concomitant reduction in tonic inhibition. Conversely, excitatory glutamatergic synaptic transmission was increased, and NMDAR subunits were upregulated at synaptic and total protein levels. Quantitative proteomics further revealed cortex neuroadaptations of key pro-excitatory mediators and synaptic plasticity pathways highlighted by Ca2+/calmodulin-dependent protein kinase II (CAMKII), MAPK, and PKC signaling. Thus, reduced inhibitory GABAergic tone and elevated glutamatergic neurotransmission contribute to disrupted excitation/inhibition balance and reduced BZ therapeutic power with benzodiazepine tolerance.
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Affiliation(s)
- Joshua M Lorenz-Guertin
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Nadya Povysheva
- Department of Neuroscience and Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - Caitlyn A Chapman
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Matthew L MacDonald
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Marco Fazzari
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Aparna Nigam
- Department of Neuroscience and Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jessica L Nuwer
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Sabyasachi Das
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Megan L Brady
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Katarina Vajn
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Matthew J Bambino
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Susan T Weintraub
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antoni, TX, USA
| | - Jon W Johnson
- Department of Neuroscience and Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - Tija C Jacob
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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8
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Puig-Bosch X, Ballmann M, Bieletzki S, Antkowiak B, Rudolph U, Zeilhofer HU, Rammes G. Neurosteroids Mediate Neuroprotection in an In Vitro Model of Hypoxic/Hypoglycaemic Excitotoxicity via δ-GABA A Receptors without Affecting Synaptic Plasticity. Int J Mol Sci 2023; 24:ijms24109056. [PMID: 37240402 DOI: 10.3390/ijms24109056] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 05/17/2023] [Accepted: 05/19/2023] [Indexed: 05/28/2023] Open
Abstract
Neurosteroids and benzodiazepines are modulators of the GABAA receptors, thereby causing anxiolysis. Furthermore, benzodiazepines such as midazolam are known to cause adverse side-effects on cognition upon administration. We previously found that midazolam at nanomolar concentrations (10 nM) blocked long-term potentiation (LTP). Here, we aim to study the effect of neurosteroids and their synthesis using XBD173, which is a synthetic compound that promotes neurosteroidogenesis by binding to the translocator protein 18 kDa (TSPO), since they might provide anxiolytic activity with a favourable side-effect profile. By means of electrophysiological measurements and the use of mice with targeted genetic mutations, we revealed that XBD173, a selective ligand of the translocator protein 18 kDa (TSPO), induced neurosteroidogenesis. In addition, the exogenous application of potentially synthesised neurosteroids (THDOC and allopregnanolone) did not depress hippocampal CA1-LTP, the cellular correlate of learning and memory. This phenomenon was observed at the same concentrations that neurosteroids conferred neuroprotection in a model of ischaemia-induced hippocampal excitotoxicity. In conclusion, our results indicate that TSPO ligands are promising candidates for post-ischaemic recovery exerting neuroprotection, in contrast to midazolam, without detrimental effects on synaptic plasticity.
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Affiliation(s)
- Xènia Puig-Bosch
- Department of Anaesthesiology and Intensive Care Medicine, Medical School, Klinikum Rechts der Isar, Technical University Munich, 81675 Munich, Germany
- BCN-AIM Lab, Departament de Matemàtiques i Informàtica, Universitat de Barcelona, 08007 Barcelona, Spain
| | - Markus Ballmann
- Department of Anaesthesiology and Intensive Care Medicine, Medical School, Klinikum Rechts der Isar, Technical University Munich, 81675 Munich, Germany
| | - Stefan Bieletzki
- Department of Anaesthesiology and Intensive Care Medicine, Experimental Anaesthesiology Section, Eberhard Karls University, 72072 Tübingen, Germany
| | - Bernd Antkowiak
- Department of Anaesthesiology and Intensive Care Medicine, Experimental Anaesthesiology Section, Eberhard Karls University, 72072 Tübingen, Germany
| | - Uwe Rudolph
- Department of Comparative Biosciences, and Carl R. Woese Institute for Genomic Biology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zürich, 8057 Zürich, Switzerland
- Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zürich, 8092 Zürich, Switzerland
| | - Gerhard Rammes
- Department of Anaesthesiology and Intensive Care Medicine, Medical School, Klinikum Rechts der Isar, Technical University Munich, 81675 Munich, Germany
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9
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Goldschen-Ohm MP. Benzodiazepine Modulation of GABA A Receptors: A Mechanistic Perspective. Biomolecules 2022; 12:biom12121784. [PMID: 36551212 PMCID: PMC9775625 DOI: 10.3390/biom12121784] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 11/23/2022] [Accepted: 11/26/2022] [Indexed: 12/05/2022] Open
Abstract
Benzodiazepines (BZDs) are a class of widely prescribed psychotropic drugs that target GABAA receptors (GABAARs) to tune inhibitory synaptic signaling throughout the central nervous system. Despite knowing their molecular target for over 40 years, we still do not fully understand the mechanism of modulation at the level of the channel protein. Nonetheless, functional studies, together with recent cryo-EM structures of GABAA(α1)2(βX)2(γ2)1 receptors in complex with BZDs, provide a wealth of information to aid in addressing this gap in knowledge. Here, mechanistic interpretations of functional and structural evidence for the action of BZDs at GABAA(α1)2(βX)2(γ2)1 receptors are reviewed. The goal is not to describe each of the many studies that are relevant to this discussion nor to dissect in detail all the effects of individual mutations or perturbations but rather to highlight general mechanistic principles in the context of recent structural information.
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10
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Structural and dynamic mechanisms of GABA A receptor modulators with opposing activities. Nat Commun 2022; 13:4582. [PMID: 35933426 PMCID: PMC9357065 DOI: 10.1038/s41467-022-32212-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 07/21/2022] [Indexed: 12/02/2022] Open
Abstract
γ-Aminobutyric acid type A (GABAA) receptors are pentameric ligand-gated ion channels abundant in the central nervous system and are prolific drug targets for treating anxiety, sleep disorders and epilepsy. Diverse small molecules exert a spectrum of effects on γ-aminobutyric acid type A (GABAA) receptors by acting at the classical benzodiazepine site. They can potentiate the response to GABA, attenuate channel activity, or counteract modulation by other ligands. Structural mechanisms underlying the actions of these drugs are not fully understood. Here we present two high-resolution structures of GABAA receptors in complex with zolpidem, a positive allosteric modulator and heavily prescribed hypnotic, and DMCM, a negative allosteric modulator with convulsant and anxiogenic properties. These two drugs share the extracellular benzodiazepine site at the α/γ subunit interface and two transmembrane sites at β/α interfaces. Structural analyses reveal a basis for the subtype selectivity of zolpidem that underlies its clinical success. Molecular dynamics simulations provide insight into how DMCM switches from a negative to a positive modulator as a function of binding site occupancy. Together, these findings expand our understanding of how GABAA receptor allosteric modulators acting through a common site can have diverging activities. GABAA receptors are important targets for anxiety, sedation and anesthesia. Here, the authors present structures bound by zolpidem (Ambien), the most prescribed hypnotic in the US, and DMCM, a negative modulator, providing insights into receptor modulation.
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11
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MacDonald T, Gallo AT, Basso-Hulse G, Hulse GK. Outcomes of patients treated with low-dose flumazenil for benzodiazepine detoxification: A description of 26 participants. Drug Alcohol Depend 2022; 237:109517. [PMID: 35688053 DOI: 10.1016/j.drugalcdep.2022.109517] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 05/23/2022] [Accepted: 05/27/2022] [Indexed: 11/25/2022]
Abstract
INTRODUCTION Benzodiazepines are commonly prescribed for a variety of indications and can be employed in the short- and long-term. While they are efficacious, issues arise from long-term use with the emergence of dependence and tolerance to doses within the therapeutic range and beyond. Discontinuation from benzodiazepines can be problematic for patients and may result in a withdrawal syndrome, which can be protracted and last months to years. METHODS 26 participants received low-dose subcutaneous flumazenil infusions (4 mg/24 h for approximately eight days) as part of a randomised control crossover trial. Return to benzodiazepine use was assessed monthly for three months based on the benzodiazepine use in the previous week. Where data was not available, the treating psychiatrist examined patient files and clinical documents to determine benzodiazepine use. Withdrawal and craving scores were also measured. RESULTS Abstinence rates from benzodiazepines at one-, two-, and three-month follow ups were 65.4 %, 50.0 %, and 46.2 % respectively. When considering patient files and clinical documents for those lost to follow-up, abstinence rates were higher at 73.1 %, 65.4 % and 61.5 % at the one-, two-, and three-month follow ups respectively. Withdrawal and craving scores were higher in those that had returned to any benzodiazepine use. CONCLUSION Self-reported rates of abstinence from benzodiazepines at three months was between 46.2 % and 61.5 %. Flumazenil may yield greater success than benzodiazepine tapering from high dose benzodiazepine use (≥30 mg diazepam equivalent). Further research should compare abstinence rates after treatment with flumazenil compared to benzodiazepine tapering in high dose benzodiazepine users.
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Affiliation(s)
- T MacDonald
- Currumbin Clinic, Currumbin, Queensland, Australia; School of Medicine, Griffith University, Australia.
| | - A T Gallo
- Division of Psychiatry, Medical School, the University of Western Australia, Australia; Fresh Start Recovery Programme, Subiaco, Western Australia, Australia.
| | - G Basso-Hulse
- Division of Psychiatry, Medical School, the University of Western Australia, Australia; Fresh Start Recovery Programme, Subiaco, Western Australia, Australia
| | - G K Hulse
- Division of Psychiatry, Medical School, the University of Western Australia, Australia; School of Medical and Health Sciences, Edith Cowan University, Australia; Fresh Start Recovery Programme, Subiaco, Western Australia, Australia
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12
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Why won't it stop? The dynamics of benzodiazepine resistance in status epilepticus. Nat Rev Neurol 2022; 18:428-441. [PMID: 35538233 DOI: 10.1038/s41582-022-00664-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/19/2022] [Indexed: 11/08/2022]
Abstract
Status epilepticus is a life-threatening neurological emergency that affects both adults and children. Approximately 36% of episodes of status epilepticus do not respond to the current preferred first-line treatment, benzodiazepines. The proportion of episodes that are refractory to benzodiazepines is higher in low-income and middle-income countries (LMICs) than in high-income countries (HICs). Evidence suggests that longer episodes of status epilepticus alter brain physiology, thereby contributing to the emergence of benzodiazepine resistance. Such changes include alterations in GABAA receptor function and in the transmembrane gradient for chloride, both of which erode the ability of benzodiazepines to enhance inhibitory synaptic signalling. Often, current management guidelines for status epilepticus do not account for these duration-related changes in pathophysiology, which might differentially impact individuals in LMICs, where the average time taken to reach medical attention is longer than in HICs. In this Perspective article, we aim to combine clinical insights and the latest evidence from basic science to inspire a new, context-specific approach to efficiently managing status epilepticus.
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13
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Wu J, Hou Z, Wang Y, Chen L, Lian C, Meng Q, Zhang C, Li X, Huang L, Yu H. Discovery of 7-alkyloxy- [1,2,4] triazolo[1,5-a] pyrimidine derivatives as selective positive modulators of GABA A1 and GABA A4 receptors with potent antiepileptic activity. Bioorg Chem 2021; 119:105565. [PMID: 34929519 DOI: 10.1016/j.bioorg.2021.105565] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 12/09/2021] [Accepted: 12/13/2021] [Indexed: 12/28/2022]
Abstract
A series of 7-alkoxy - [1,2,4] triazolo [1, 5-a] pyrimidine derivatives were designed and synthesized. Maximal electroshock (MES) and pentylenetetrazole (PTZ) tests were utilized to access their anticonvulsant activity. Most of the series of compounds exhibited significant anti-seizure effects. Further studies demonstrated that the anticonvulsant activity of these compounds mainly depended on their allosteric potentiation of GABAA receptors. Among them, compound 10c was picked for the mechanism study due to its potent activity. The compound is more sensitive to subunit configurations of synaptic α1β2γ2 and extrasynaptic α4β3δ GABAA receptors, but there were no effects on NMDA receptors and Nav1.2 sodium channels. Meanwhile, 10c acted on the sites of GABAA receptors distinct from commonly used anticonvulsants benzodiazepines and barbiturates. Furthermore, studies from native neurons demonstrated that compound 10c also potentiated the activity of native GABAA receptors and reduced action potential firings in cultured cortical neurons. Such structural compounds may lay a foundation for further designing novel antiepileptic molecules.
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Affiliation(s)
- Jun Wu
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, 1 Xiannongtan Street, Xicheng district, Beijing 100050, China
| | - Zhipeng Hou
- College of Chemical Engineering, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042, China
| | - Yan Wang
- College of Chemical Engineering, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042, China
| | - Liping Chen
- College of Chemical Engineering, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042, China
| | - Chengxi Lian
- College of Chemical Engineering, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042, China
| | - Qingfei Meng
- College of Chemical Engineering, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042, China
| | - Chaoying Zhang
- College of Chemical Engineering, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042, China
| | - Xiufen Li
- College of Chemical Engineering, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042, China
| | - Longjiang Huang
- College of Chemical Engineering, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042, China; State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, 1 Xiannongtan Street, Xicheng district, Beijing 100050, China.
| | - Haibo Yu
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, 1 Xiannongtan Street, Xicheng district, Beijing 100050, China.
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14
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Sexton CA, Penzinger R, Mortensen M, Bright DP, Smart TG. Structural determinants and regulation of spontaneous activity in GABA A receptors. Nat Commun 2021; 12:5457. [PMID: 34526505 PMCID: PMC8443696 DOI: 10.1038/s41467-021-25633-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 08/24/2021] [Indexed: 11/25/2022] Open
Abstract
GABAA receptors are vital for controlling neuronal excitability and can display significant levels of constitutive activity that contributes to tonic inhibition. However, the mechanisms underlying spontaneity are poorly understood. Here we demonstrate a strict requirement for β3 subunit incorporation into receptors for spontaneous gating, facilitated by α4, α6 and δ subunits. The crucial molecular determinant involves four amino acids (GKER) in the β3 subunit's extracellular domain, which interacts with adjacent receptor subunits to promote transition to activated, open channel conformations. Spontaneous activity is further regulated by β3 subunit phosphorylation and by allosteric modulators including neurosteroids and benzodiazepines. Promoting spontaneous activity reduced neuronal excitability, indicating that spontaneous currents will alter neural network activity. This study demonstrates how regional diversity in GABAA receptor isoform, protein kinase activity, and neurosteroid levels, can impact on tonic inhibition through the modulation of spontaneous GABAA receptor gating.
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Affiliation(s)
- Craig A Sexton
- Department of Neuroscience, Physiology & Pharmacology, UCL, London, UK
| | - Reka Penzinger
- Department of Neuroscience, Physiology & Pharmacology, UCL, London, UK
| | - Martin Mortensen
- Department of Neuroscience, Physiology & Pharmacology, UCL, London, UK
| | - Damian P Bright
- Department of Neuroscience, Physiology & Pharmacology, UCL, London, UK
| | - Trevor G Smart
- Department of Neuroscience, Physiology & Pharmacology, UCL, London, UK.
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15
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Synthesis and biological evaluation of benzodiazepines containing a pentafluorosulfanyl group. Tetrahedron 2021. [DOI: 10.1016/j.tet.2021.132020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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16
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Kim JJ, Hibbs RE. Direct Structural Insights into GABA A Receptor Pharmacology. Trends Biochem Sci 2021; 46:502-517. [PMID: 33674151 DOI: 10.1016/j.tibs.2021.01.011] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 01/08/2021] [Accepted: 01/25/2021] [Indexed: 12/18/2022]
Abstract
GABAA receptors are pentameric ligand-gated ion channels that mediate most fast neuronal inhibition in the brain. In addition to their important physiological roles, they are noteworthy in their rich pharmacology; prominent drugs used for anxiety, insomnia, and general anesthesia act through positive modulation of GABAA receptors. Direct structural information for how these drugs work was absent until recently. Efforts in structural biology over the past few years have revealed how important drug classes and natural products interact with the GABAA receptor, providing a foundation for studies in dynamics and structure-guided drug design. Here, we review recent developments in GABAA receptor structural pharmacology, focusing on subunit assemblies of the receptor found at synapses.
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Affiliation(s)
- Jeong Joo Kim
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Ryan E Hibbs
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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17
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Amundarain MJ, Caffarena ER, Costabel MD. How does α 1Histidine102 affect the binding of modulators to α 1β 2γ 2 GABA A receptors? molecular insights from in silico experiments. Phys Chem Chem Phys 2021; 23:3993-4006. [PMID: 33554986 DOI: 10.1039/d0cp05081d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The activation of GABAA receptors by the neurotransmitter gamma-aminobutyric acid mediates the rapid inhibition response in the central nervous system of mammals. Many neurological and mental health disorders arise from alterations in the structure or function of these pentameric ion channels. GABAA receptors are targets for numerous drugs, including benzodiazepines, which bind to α1β2γ2 GABAA receptors with high affinity to a site in the extracellular domain, between subunits α1 and γ2. It has been established experimentally that the binding of these drugs depends on the presence of one particular amino acid in the α1 subunit: histidine 102. However, the specific role it plays in the intermolecular interaction has not been elucidated. In this work, we applied in silico methods to understand whether certain protonation and rotamer states of α1His102 facilitate the binding of modulators. We analysed diazepam binding, a benzodiazepine, and the antagonist flumazenil to the GABAA receptor using molecular dynamics simulations and adaptive biasing force simulations. The binding free energy follows changes in the protonation state for both ligands, and rotameric states of α1His102 were specific for the different compounds, suggesting distinct preferences for positive allosteric modulators and antagonists. Moreover, in the presence of diazepam and favoured by a neutral tautomer, we identified a water molecule that links loops A, B, and C and may be relevant to the modulation mechanism.
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Affiliation(s)
- María Julia Amundarain
- Instituto de Física del Sur (IFISUR), Departamento de Física, Universidad Nacional del Sur (UNS), CONICET, Av. L. N. Alem 1253, B8000CPB - Bahía Blanca, Argentina.
| | - Ernesto Raúl Caffarena
- Programa de Computação Científica - PROCC, Fundação Oswaldo Cruz, Manguinhos, CEP 21040-360, Av. Brasil 4365, Rio de Janeiro, RJ, Brazil
| | - Marcelo Daniel Costabel
- Instituto de Física del Sur (IFISUR), Departamento de Física, Universidad Nacional del Sur (UNS), CONICET, Av. L. N. Alem 1253, B8000CPB - Bahía Blanca, Argentina.
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18
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Han W, Shepard RD, Lu W. Regulation of GABA ARs by Transmembrane Accessory Proteins. Trends Neurosci 2021; 44:152-165. [PMID: 33234346 PMCID: PMC7855156 DOI: 10.1016/j.tins.2020.10.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 09/08/2020] [Accepted: 10/20/2020] [Indexed: 12/13/2022]
Abstract
The vast majority of fast inhibitory transmission in the brain is mediated by GABA acting on GABAA receptors (GABAARs), which provides inhibitory balance to excitatory drive and controls neuronal output. GABAARs are also effectively targeted by clinically important drugs for treatment in a number of neurological disorders. It has long been hypothesized that function and pharmacology of GABAARs are determined by the channel pore-forming subunits. However, recent studies have provided new dimensions in studying GABAARs due to several transmembrane proteins that interact with GABAARs and modulate their trafficking and function. In this review, we summarize recent findings on these novel GABAAR transmembrane regulators and highlight a potential avenue to develop new GABAAR psychopharmacology by targeting these receptor-associated membrane proteins.
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Affiliation(s)
- Wenyan Han
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ryan D Shepard
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Wei Lu
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
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19
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Castellano D, Shepard RD, Lu W. Looking for Novelty in an "Old" Receptor: Recent Advances Toward Our Understanding of GABA ARs and Their Implications in Receptor Pharmacology. Front Neurosci 2021; 14:616298. [PMID: 33519367 PMCID: PMC7841293 DOI: 10.3389/fnins.2020.616298] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Accepted: 12/14/2020] [Indexed: 12/16/2022] Open
Abstract
Diverse populations of GABAA receptors (GABAARs) throughout the brain mediate fast inhibitory transmission and are modulated by various endogenous ligands and therapeutic drugs. Deficits in GABAAR signaling underlie the pathophysiology behind neurological and neuropsychiatric disorders such as epilepsy, anxiety, and depression. Pharmacological intervention for these disorders relies on several drug classes that target GABAARs, such as benzodiazepines and more recently neurosteroids. It has been widely demonstrated that subunit composition and receptor stoichiometry impact the biophysical and pharmacological properties of GABAARs. However, current GABAAR-targeting drugs have limited subunit selectivity and produce their therapeutic effects concomitantly with undesired side effects. Therefore, there is still a need to develop more selective GABAAR pharmaceuticals, as well as evaluate the potential for developing next-generation drugs that can target accessory proteins associated with native GABAARs. In this review, we briefly discuss the effects of benzodiazepines and neurosteroids on GABAARs, their use as therapeutics, and some of the pitfalls associated with their adverse side effects. We also discuss recent advances toward understanding the structure, function, and pharmacology of GABAARs with a focus on benzodiazepines and neurosteroids, as well as newly identified transmembrane proteins that modulate GABAARs.
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Affiliation(s)
- David Castellano
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Ryan David Shepard
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Wei Lu
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
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20
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Richter G, Liao VWY, Ahring PK, Chebib M. The Z-Drugs Zolpidem, Zaleplon, and Eszopiclone Have Varying Actions on Human GABA A Receptors Containing γ1, γ2, and γ3 Subunits. Front Neurosci 2020; 14:599812. [PMID: 33328871 PMCID: PMC7710685 DOI: 10.3389/fnins.2020.599812] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 10/26/2020] [Indexed: 11/13/2022] Open
Abstract
γ-Aminobutyric-acid type A (GABA A ) receptors expressing the γ1 or γ3 subunit are only found within a few regions of the brain, some of which are involved in sleep. No known compounds have been reported to selectively target γ1- or γ3-containing GABA A receptors. Pharmacological assessments of this are conflicting, possibly due to differences in experimental models, conditions, and exact protocols when reporting efficacies and potencies. In this study, we evaluated the modulatory properties of five non-benzodiazepine Z-drugs (zaleplon, indiplon, eszopiclone, zolpidem, and alpidem) used in sleep management and the benzodiazepine, diazepam on human α1β2γ receptors using all three γ subtypes. This was accomplished using concatenated GABA A pentamers expressed in Xenopus laevis oocytes and measured via two-electrode voltage clamp. This approach removes the potential for single subunits to form erroneous receptors that could contribute to the pharmacological assessment of these compounds. No compound tested had significant effects on γ1-containing receptors below 10 μM. Interestingly, zaleplon and indiplon were found to modulate γ3-containing receptors equally as efficacious as γ2-containing receptors. Furthermore, zaleplon had a higher potency for γ3- than for γ2-containing receptors, indicating certain therapeutic effects could occur via these γ3-containing receptors. Eszopiclone modulated γ3-containing receptors with reduced efficacy but no reduction in potency. These data demonstrate that the imidazopyridines zaleplon and indiplon are well suited to further investigate potential γ3 effects on sleep in vivo.
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Affiliation(s)
- Grant Richter
- Brain and Mind Centre, Sydney Pharmacy School, The University of Sydney, Sydney, NSW, Australia
| | | | | | - Mary Chebib
- Brain and Mind Centre, Sydney Pharmacy School, The University of Sydney, Sydney, NSW, Australia
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21
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Blom AEM, Su JY, Repka LM, Reisman SE, Dougherty DA. Synthesis and Biological Evaluation of Pyrroloindolines as Positive Allosteric Modulators of the α1β2γ2 GABA A Receptor. ACS Med Chem Lett 2020; 11:2204-2211. [PMID: 33214830 DOI: 10.1021/acsmedchemlett.0c00340] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 09/15/2020] [Indexed: 12/21/2022] Open
Abstract
γ-Aminobutyric acid type A (GABAA) receptors are key mediators of central inhibitory neurotransmission and have been implicated in several disorders of the central nervous system. Some positive allosteric modulators (PAMs) of this receptor provide great therapeutic benefits to patients. However, adverse effects remain a challenge. Selective targeting of GABAA receptors could mitigate this problem. Here, we describe the synthesis and functional evaluation of a novel series of pyrroloindolines that display significant modulation of the GABAA receptor, acting as PAMs. We found that halogen incorporation at the C5 position greatly increased the PAM potency relative to the parent ligand, while substitutions at other positions generally decreased potency. Mutagenesis studies suggest that the binding site lies at the top of the transmembrane domain.
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Affiliation(s)
- Annet E M Blom
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Justin Y Su
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Lindsay M Repka
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Sarah E Reisman
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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22
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Niespodziany I, Ghisdal P, Mullier B, Wood M, Provins L, Kaminski RM, Wolff C. Functional characterization of the antiepileptic drug candidate, padsevonil, on GABA A receptors. Epilepsia 2020; 61:914-923. [PMID: 32297665 PMCID: PMC7383892 DOI: 10.1111/epi.16497] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 03/09/2020] [Accepted: 03/17/2020] [Indexed: 02/03/2023]
Abstract
OBJECTIVE The antiepileptic drug candidate, padsevonil, is the first in a novel class of drugs designed to interact with both presynaptic and postsynaptic therapeutic targets: synaptic vesicle 2 proteins and γ-aminobutyric acid type A receptors (GABAA Rs), respectively. Functional aspects of padsevonil at the postsynaptic target, GABAA Rs, were characterized in experiments reported here. METHODS The effect of padsevonil on GABA-mediated Cl- currents was determined by patch clamp on recombinant human GABAA Rs (α1β2γ2) stably expressed in a CHO-K1 cell line and on native GABAA Rs in cultured rat primary cortical neurons. Padsevonil selectivity for GABAA R subtypes was evaluated using a two-electrode voltage clamp on recombinant human GABAA Rs (α1-5/β2/γ2) in Xenopus oocytes. RESULTS In recombinant GABAA Rs, padsevonil did not evoke Cl- currents in the absence of the agonist GABA. However, when co-administered with GABA at effective concentration (EC)20 , padsevonil potentiated GABA responses by 167% (EC50 138 nmol/L) and demonstrated a relative efficacy of 41% compared with zolpidem, a reference benzodiazepine site agonist. Similarly, padsevonil demonstrated GABA-potentiating activity at native GABAA Rs (EC50 208 nmol/L) in cultured rat cortical neurons. Padsevonil also potentiated GABA (EC20 ) responses in GABAA Rs expressed in oocytes, with higher potency at α1- and α5-containing receptors (EC50 295 and 281 nmol/L) than at α2- and α3-containing receptors (EC50 1737 and 2089 nmol/L). Compared with chlordiazepoxide-a nonselective, full GABAA R agonist-the relative efficacy of padsevonil was 60% for α1β2γ2, 26% for α2β2γ2, 56% for α3β2γ2, and 41% for α5β2γ2; no activity was observed at benzodiazepine-insensitive α4β2γ2 receptors. SIGNIFICANCE Results of functional investigations on recombinant and native neuronal GABAA Rs show that padsevonil acts as a positive allosteric modulator of these receptors, with a partial agonist profile at the benzodiazepine site. These properties may confer better tolerability and lower potential for tolerance development compared with classic benzodiazepines currently used in the clinic.
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Affiliation(s)
| | - Philippe Ghisdal
- Neurosciences Therapeutic Area, UCB Pharma, Braine l'Alleud, Belgium
| | - Brice Mullier
- Neurosciences Therapeutic Area, UCB Pharma, Braine l'Alleud, Belgium
| | - Martyn Wood
- Neurosciences Therapeutic Area, UCB Pharma, Braine l'Alleud, Belgium
| | - Laurent Provins
- Neurosciences Therapeutic Area, UCB Pharma, Braine l'Alleud, Belgium
| | - Rafal M Kaminski
- Neurosciences Therapeutic Area, UCB Pharma, Braine l'Alleud, Belgium
| | - Christian Wolff
- Neurosciences Therapeutic Area, UCB Pharma, Braine l'Alleud, Belgium
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Doble A, Canton T, Malgouris C, Stutzmann JM, Piot O, Bardone MC, Pauchet C, Blanchard JC. The mechanism of action of zopiclone. Eur Psychiatry 2020; 10 Suppl 3:117s-28s. [DOI: 10.1016/0924-9338(96)80093-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
SummaryThe mechanism of action of the cyclopyrrolone hypnotic drug zopiclone involves allosteric modulation of the GABAAreceptor. Zopiclone displaces the binding of [3H]-flunitrazepam with an affinity of 28 nM, and enhances the binding of the channel blocker [35S]-TBPS. The binding of zopiclone, unlike that of hypnotic benzodiazepines, is not facilitated by GABA. Zopiclone does not distinguish between GABAA receptors containing different α-subunits (BZ1and BZ2phenotype). Studies with protein-modifying agents (egdiethylpyrocarbonate) and photoaffinity labelling suggest that cyclopyrrolones bind to a domain on the GABAA receptor different from the benzodiazepine binding domain. The consequence of this interaction with the GABAAreceptor is to potentiate responses to GABA, as can be demonstrated by electrophysiological methods. Subchronic treatment of mice with high doses of zopiclone does not produce the changes in sensitivity of the GABAAreceptor that are observed with hypnotic benzodiazepines.
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Tonon MC, Vaudry H, Chuquet J, Guillebaud F, Fan J, Masmoudi-Kouki O, Vaudry D, Lanfray D, Morin F, Prevot V, Papadopoulos V, Troadec JD, Leprince J. Endozepines and their receptors: Structure, functions and pathophysiological significance. Pharmacol Ther 2020; 208:107386. [DOI: 10.1016/j.pharmthera.2019.06.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 06/20/2019] [Indexed: 02/06/2023]
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Vossen LE, Cerveny D, Österkrans M, Thörnqvist PO, Jutfelt F, Fick J, Brodin T, Winberg S. Chronic Exposure to Oxazepam Pollution Produces Tolerance to Anxiolytic Effects in Zebrafish ( Danio rerio). ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:1760-1769. [PMID: 31934760 DOI: 10.1021/acs.est.9b06052] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Environmental concentrations of the anxiolytic drug oxazepam have been found to disrupt antipredator behaviors of wild fish. Most experiments exposed fish for a week, while evidence from mammals suggests that chronic exposure to therapeutic concentrations of benzodiazepines (such as oxazepam) results in the development of tolerance to the anxiolytic effects. If tolerance can also develop in response to the low concentrations found in the aquatic environment, it could mitigate the negative effects of oxazepam pollution. In the current study, we exposed wild-caught zebrafish to oxazepam (∼7 μg L-1) for 7 or 28 days and evaluated behavioral and physiological parameters at both time points. Females showed reduced diving responses to conspecific alarm pheromone after 7 days, but not after 28 days, indicating that they had developed tolerance to the anxiolytic effects of the drug. Zebrafish males were not affected by this oxazepam concentration, in line with earlier results. Serotonin turnover (ratio 5-HIAA/5-HT) was reduced in exposed females and males after 28 days, indicating that brain neurochemistry had not normalized. Post-confinement cortisol concentrations and gene expression of corticotropin-releasing hormone (CRH) were not affected by oxazepam. We did not find evidence that chronically exposed fish had altered relative expression of GABAA receptor subunits, suggesting that some other still unknown mechanism caused the developed tolerance.
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Affiliation(s)
- Laura E Vossen
- Department of Neuroscience , Uppsala University , SE-751 24 Uppsala , Sweden
| | - Daniel Cerveny
- Department of Chemistry , Umeå University , SE-901 87 Umeå , Sweden
- Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses , University of South Bohemia in Ceske Budejovice , Zátiší 728/II , 389 25 Vodňany , Czech Republic
| | - Marcus Österkrans
- Department of Neuroscience , Uppsala University , SE-751 24 Uppsala , Sweden
| | - Per-Ove Thörnqvist
- Department of Neuroscience , Uppsala University , SE-751 24 Uppsala , Sweden
| | - Fredrik Jutfelt
- Department of Biology , Norwegian University of Science and Technology , EU2-167 Trondheim , Norway
| | - Jerker Fick
- Department of Chemistry , Umeå University , SE-901 87 Umeå , Sweden
| | - Tomas Brodin
- Department of Wildlife, Fish and Environmental Studies , Swedish University of Agricultural Sciences , SE-901 83 Umeå , Sweden
| | - Svante Winberg
- Department of Neuroscience , Uppsala University , SE-751 24 Uppsala , Sweden
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26
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Witkin JM, Li G, Golani LK, Xiong W, Smith JL, Ping X, Rashid F, Jahan R, Cerne R, Cook JM, Jin X. The Positive Allosteric Modulator of α2/3-Containing GABA A Receptors, KRM-II-81, Is Active in Pharmaco-Resistant Models of Epilepsy and Reduces Hyperexcitability after Traumatic Brain Injury. J Pharmacol Exp Ther 2020; 372:83-94. [PMID: 31694876 PMCID: PMC6927408 DOI: 10.1124/jpet.119.260968] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Accepted: 10/17/2019] [Indexed: 12/14/2022] Open
Abstract
The imidizodiazepine, 5-(8-ethynyl-6-(pyridin-2-yl)-4H-benzo[f]imidazo[1,5-a][1,4]diazepin-3-yl)oxazole (KRM-II-81), is selective for α2/3-containing GABAA receptors. KRM-II-81 dampens seizure activity in rodent models with enhanced efficacy and reduced motor-impairment compared with diazepam. In the present study, KRM-II-81 was studied in assays designed to detect antiepileptics with improved chances of impacting pharmaco-resistant epilepsies. The potential for reducing neural hyperactivity weeks after traumatic brain injury was also studied. KRM-II-81 suppressed convulsions in corneal-kindled mice. Mice with kainate-induced mesial temporal lobe seizures exhibited spontaneous recurrent hippocampal paroxysmal discharges that were significantly reduced by KRM-II-81 (15 mg/kg, orally). KRM-II-81 also decreased convulsions in rats undergoing amygdala kindling in the presence of lamotrigine (lamotrigine-insensitive model) (ED50 = 19 mg/kg, i.p.). KRM-II-81 reduced focal and generalized seizures in a kainate-induced chronic epilepsy model in rats (20 mg/kg, i.p., three times per day). In mice with damage to the left cerebral cortex by controlled-cortical impact, enduring neuronal hyperactivity was dampened by KRM-II-81 (10 mg/kg, i.p.) as observed through in vivo two-photon imaging of layer II/III pyramidal neurons in GCaMP6-expressing transgenic mice. No notable side effects emerged up to doses of 300 mg/kg KRM-II-81. Molecular modeling studies were conducted: docking in the binding site of the α1β3γ2L GABAA receptor showed that replacing the C8 chlorine atom of alprazolam with the acetylene of KRM-II-81 led to loss of the key interaction with α1His102, providing a structural rationale for its low affinity for α1-containing GABAA receptors compared with benzodiazepines such as alprazolam. Overall, these findings predict that KRM-II-81 has improved therapeutic potential for epilepsy and post-traumatic epilepsy. SIGNIFICANCE STATEMENT: We describe the effects of a relatively new orally bioavailable small molecule in rodent models of pharmaco-resistant epilepsy and traumatic brain injury. KRM-II-81 is more potent and generally more efficacious than standard-of-care antiepileptics. In silico docking experiments begin to describe the structural basis for the relative lack of motor impairment induced by KRM-II-81. KRM-II-81 has unique structural and anticonvulsant effects, predicting its potential as an improved antiepileptic drug and novel therapy for post-traumatic epilepsy.
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Affiliation(s)
- Jeffrey M Witkin
- Department of Neurologic Surgery, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., R.C., X.J.); Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin (J.M.W., G.L., L.K.G., F.R., R.J., J.M.C.); Department of Anatomy, Cell Biology, and Physiology, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., X.J.); and Laboratory of Antiepileptic Drug Discovery, St. Vincent's Hospital, Indianapolis, Indiana (J.L.S.)
| | - Guanguan Li
- Department of Neurologic Surgery, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., R.C., X.J.); Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin (J.M.W., G.L., L.K.G., F.R., R.J., J.M.C.); Department of Anatomy, Cell Biology, and Physiology, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., X.J.); and Laboratory of Antiepileptic Drug Discovery, St. Vincent's Hospital, Indianapolis, Indiana (J.L.S.)
| | - Lalit K Golani
- Department of Neurologic Surgery, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., R.C., X.J.); Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin (J.M.W., G.L., L.K.G., F.R., R.J., J.M.C.); Department of Anatomy, Cell Biology, and Physiology, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., X.J.); and Laboratory of Antiepileptic Drug Discovery, St. Vincent's Hospital, Indianapolis, Indiana (J.L.S.)
| | - Wenhui Xiong
- Department of Neurologic Surgery, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., R.C., X.J.); Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin (J.M.W., G.L., L.K.G., F.R., R.J., J.M.C.); Department of Anatomy, Cell Biology, and Physiology, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., X.J.); and Laboratory of Antiepileptic Drug Discovery, St. Vincent's Hospital, Indianapolis, Indiana (J.L.S.)
| | - Jodi L Smith
- Department of Neurologic Surgery, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., R.C., X.J.); Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin (J.M.W., G.L., L.K.G., F.R., R.J., J.M.C.); Department of Anatomy, Cell Biology, and Physiology, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., X.J.); and Laboratory of Antiepileptic Drug Discovery, St. Vincent's Hospital, Indianapolis, Indiana (J.L.S.)
| | - Xingjie Ping
- Department of Neurologic Surgery, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., R.C., X.J.); Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin (J.M.W., G.L., L.K.G., F.R., R.J., J.M.C.); Department of Anatomy, Cell Biology, and Physiology, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., X.J.); and Laboratory of Antiepileptic Drug Discovery, St. Vincent's Hospital, Indianapolis, Indiana (J.L.S.)
| | - Farjana Rashid
- Department of Neurologic Surgery, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., R.C., X.J.); Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin (J.M.W., G.L., L.K.G., F.R., R.J., J.M.C.); Department of Anatomy, Cell Biology, and Physiology, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., X.J.); and Laboratory of Antiepileptic Drug Discovery, St. Vincent's Hospital, Indianapolis, Indiana (J.L.S.)
| | - Rajwana Jahan
- Department of Neurologic Surgery, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., R.C., X.J.); Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin (J.M.W., G.L., L.K.G., F.R., R.J., J.M.C.); Department of Anatomy, Cell Biology, and Physiology, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., X.J.); and Laboratory of Antiepileptic Drug Discovery, St. Vincent's Hospital, Indianapolis, Indiana (J.L.S.)
| | - Rok Cerne
- Department of Neurologic Surgery, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., R.C., X.J.); Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin (J.M.W., G.L., L.K.G., F.R., R.J., J.M.C.); Department of Anatomy, Cell Biology, and Physiology, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., X.J.); and Laboratory of Antiepileptic Drug Discovery, St. Vincent's Hospital, Indianapolis, Indiana (J.L.S.)
| | - James M Cook
- Department of Neurologic Surgery, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., R.C., X.J.); Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin (J.M.W., G.L., L.K.G., F.R., R.J., J.M.C.); Department of Anatomy, Cell Biology, and Physiology, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., X.J.); and Laboratory of Antiepileptic Drug Discovery, St. Vincent's Hospital, Indianapolis, Indiana (J.L.S.)
| | - Xiaoming Jin
- Department of Neurologic Surgery, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., R.C., X.J.); Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin (J.M.W., G.L., L.K.G., F.R., R.J., J.M.C.); Department of Anatomy, Cell Biology, and Physiology, Indiana University School of Medicine, Indianapolis, Indiana (W.X., X.P., X.J.); and Laboratory of Antiepileptic Drug Discovery, St. Vincent's Hospital, Indianapolis, Indiana (J.L.S.)
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27
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Walia V, Garg C, Garg M. Amantadine exerts anxiolytic like effect in mice: Evidences for the involvement of nitrergic and GABAergic signaling pathways. Behav Brain Res 2019; 380:112432. [PMID: 31838141 DOI: 10.1016/j.bbr.2019.112432] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 12/08/2019] [Accepted: 12/11/2019] [Indexed: 01/08/2023]
Abstract
Amantadine is a glutamatergic antagonist that works by inhibiting the NMDA receptor. Besides the inhibition of NMDA receptors amantadine also stabilizes the glutamatergic system and protects the neurons against the NMDA toxicity. Amantadine treatment also reduces the production of NO and metabolism of GABA. Therefore amantadine modulates glutamate, GABA and NO which are known to be implicated in the pathogenesis of anxiety and related behavior. The present study was designed to investigate the anxiolytic like effect of amantadine in mice. Nitrergic and GABAergic signaling influence in the anxiolytic like effect of amantadine was also studied. Amantadine (25, 50 and 75 mg/kg, i.p.) was administered and the anxiety related behavior was determined using light and dark box (LDB) and elevated plus maze (EPM) methods. Further, the effect of various treatments on the whole brain glutamate, nitrite and GABA levels were also determined. The results obtained demonstrated that the amantadine (50 mg/kg, i.p.) exerted anxiolytic like effect in mice and reduced the levels of glutamate, nitrite and GABA in the brain of mice as compared to control. Further, the influence of NO and GABA in the anxiolytic like effect of the amantadine was also determined. The results obtained demonstrated that NO donor counteracted while NO inhibitor potentiated the anxiolytic like effect of amantadine in mice. Also the combined treatment of amantadine (25 mg/kg, i.p.) and diazepam (1 mg/kg, i.p.) did not affect the anxiety related behavior, brain GABA and nitrite level of mice but reduced the levels the brain glutamate levels significantly as compared to amantadine (25 mg/kg, i.p.) and diazepam (1 mg/kg, i.p.) treated mice. Thus, amantadine exerted anxiolytic like effect in mice and the anxiolytic like effect of amantadine was modulated by nitrergic and GABAergic signaling pathway.
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Affiliation(s)
- Vaibhav Walia
- Faculty of Pharmacy, DIT University, Dehradun, India.
| | - Chanchal Garg
- Department of Pharmaceutical Sciences, Maharshi Dayanand University, Rohtak 124001, Haryana, India.
| | - Munish Garg
- Department of Pharmaceutical Sciences, Maharshi Dayanand University, Rohtak 124001, Haryana, India.
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28
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Woo J, Yang H, Yoon M, Gadhe CG, Pae AN, Cho S, Lee CJ. 3-Carene, a Phytoncide from Pine Tree Has a Sleep-enhancing Effect by Targeting the GABA A-benzodiazepine Receptors. Exp Neurobiol 2019; 28:593-601. [PMID: 31698551 PMCID: PMC6844839 DOI: 10.5607/en.2019.28.5.593] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 10/28/2019] [Accepted: 10/29/2019] [Indexed: 12/21/2022] Open
Abstract
3-Carene, a bicyclic monoterpene, is one of the major components of the pine tree essential oils. It has been reported that, in addition to its known properties as a phytoncide, 3-carene has anti-inflammatory, antimicrobial, and anxiolytic effects. We have previously demonstrated that α-pinene, the major component of pine tree, has a hypnotic effect through GABAA-benzodiazepine (BZD) receptors. However, a hypnotic effect of 3-carene has not been studied yet. Here, we report that oral administration of 3-carene increases the sleep duration and reduces sleep latency in pentobarbital- induced sleep test. 3-Carene potentiates the GABAA receptor-mediated synaptic responses by prolonging the decay time constant of inhibitory synaptic responses. These enhancing effects of 3-carene are reproduced by zolpidem, a modulator for GABAA-BZD receptor, and fully inhibited by flumazenil, an antagonist for GABAA-BZD receptor. The molecular docking of 3-carene to the BZD site of GABAA protein structure, suggests that 3-carene binds to the BZD site of α1 and ϒ2 subunits of GABAA-BZD receptor. These results indicate that, similar to α-pinene, 3-carene shows a sleep-enhancing effect by acting as a positive modulator for GABAA-BZD receptor.
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Affiliation(s)
- Junsung Woo
- Center for Neuroscience, Korea Institute of Science and Technology (KIST), Department of Neuroscience, Division of Bio- Medical Science & Technology, KIST School, Korea University of Science and Technology, Seoul 02792, Korea
| | - Hyejin Yang
- Research Division of Food Functionality, Korea Food Research Institute, Wanju 55365, Korea
| | - Minseok Yoon
- Research Division of Food Functionality, Korea Food Research Institute, Wanju 55365, Korea
| | - Changdev G Gadhe
- Convergence Research Center for Diagnosis, Treatment and Care System of Dementia, Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02791, Korea
| | - Ae Nim Pae
- Convergence Research Center for Diagnosis, Treatment and Care System of Dementia, Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02791, Korea
| | - Suengmok Cho
- Department of Food Science and Technology, Pukyong National University, Busan 48513, Korea
| | - C Justin Lee
- Center for Neuroscience, Korea Institute of Science and Technology (KIST), Department of Neuroscience, Division of Bio- Medical Science & Technology, KIST School, Korea University of Science and Technology, Seoul 02792, Korea.,Center for Cognition and Sociality, Institute for Basic Science, Daejeon 34126, Korea
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29
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Abstract
Current GABAergic sleep-promoting medications were developed pragmatically, without making use of the immense diversity of GABAA receptors. Pharmacogenetic experiments are leading to an understanding of the circuit mechanisms in the hypothalamus by which zolpidem and similar compounds induce sleep at α2βγ2-type GABAA receptors. Drugs acting at more selective receptor types, for example, at receptors containing the α2 and/or α3 subunits expressed in hypothalamic and brain stem areas, could in principle be useful as hypnotics/anxiolytics. A highly promising sleep-promoting drug, gaboxadol, which activates αβδ-type receptors failed in clinical trials. Thus, for the time being, drugs such as zolpidem, which work as positive allosteric modulators at GABAA receptors, continue to be some of the most effective compounds to treat primary insomnia.
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Affiliation(s)
- W Wisden
- Department Life Sciences, Imperial College London, London, SW7 2AZ, UK.
| | - X Yu
- Department Life Sciences, Imperial College London, London, SW7 2AZ, UK
| | - N P Franks
- Department Life Sciences, Imperial College London, London, SW7 2AZ, UK
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30
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Kasaragod VB, Schindelin H. Structure of Heteropentameric GABA A Receptors and Receptor-Anchoring Properties of Gephyrin. Front Mol Neurosci 2019; 12:191. [PMID: 31440140 PMCID: PMC6693554 DOI: 10.3389/fnmol.2019.00191] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 07/22/2019] [Indexed: 12/20/2022] Open
Abstract
γ-Aminobutyric acid type A receptors (GABAARs) mediate the majority of fast synaptic inhibition in the central nervous system (CNS). GABAARs belong to the Cys-loop superfamily of pentameric ligand-gated ion channels (pLGIC) and are assembled from 19 different subunits. As dysfunctional GABAergic neurotransmission manifests itself in neurodevelopmental disorders including epilepsy and anxiety, GABAARs are key drug targets. The majority of synaptic GABAARs are anchored at the inhibitory postsynaptic membrane by the principal scaffolding protein gephyrin, which acts as the central organizer in maintaining the architecture of the inhibitory postsynaptic density (iPSD). This interaction is mediated by the long intracellular loop located in between transmembrane helices 3 and 4 (M3–M4 loop) of the receptors and a universal receptor-binding pocket residing in the C-terminal domain of gephyrin. In 2014, the crystal structure of the β3-homopentameric GABAAR provided crucial information regarding the architecture of the receptor; however, an understanding of the structure and assembly of heteropentameric receptors at the atomic level was lacking. This review article will highlight recent advances in understanding the structure of heteropentameric synaptic GABAARs and how these structures have provided fundamental insights into the assembly of these multi-subunit receptors as well as their modulation by diverse ligands including the physiological agonist GABA. We will further discuss the role of gephyrin in the anchoring of synaptic GABAARs and glycine receptors (GlyRs), which are crucial for maintaining the architecture of the iPSD. Finally, we will also summarize how anti-malarial artemisinin drugs modulate gephyrin-mediated inhibitory neurotransmission.
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Affiliation(s)
- Vikram Babu Kasaragod
- Institute of Structural Biology, Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Hermann Schindelin
- Institute of Structural Biology, Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
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31
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Chen X, van Gerven J, Cohen A, Jacobs G. Human pharmacology of positive GABA-A subtype-selective receptor modulators for the treatment of anxiety. Acta Pharmacol Sin 2019; 40:571-582. [PMID: 30518829 DOI: 10.1038/s41401-018-0185-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Accepted: 10/10/2018] [Indexed: 12/11/2022] Open
Abstract
Anxiety disorders arise from disruptions among the highly interconnected circuits that normally serve to process the streams of potentially threatening stimuli. The resulting imbalance among these circuits can cause a fundamental misinterpretation of neural sensory information as threatening and can lead to the inappropriate emotional and behavioral responses observed in anxiety disorders. There is considerable preclinical evidence that the GABAergic system, in general, and its α2- and/or α5-subunit-containing GABA(A) receptor subtypes, in particular, are involved in the pathophysiology of anxiety disorders. However, the clinical efficacy of GABA-A α2-selective agonists for the treatment of anxiety disorders has not been unequivocally demonstrated. In this review, we present several human pharmacological studies that have been performed with the aim of identifying the pharmacologically active doses/exposure levels of several GABA-A subtype-selective novel compounds with potential anxiolytic effects. The pharmacological selectivity of novel α2-subtype-selective GABA(A) receptor partial agonists has been demonstrated by their distinct effect profiles on the neurophysiological and neuropsychological measurements that reflect the functions of multiple CNS domains compared with those of benzodiazepines, which are nonselective, full GABA(A) agonists. Normalizing the undesired pharmacodynamic side effects against the desired on-target effects on the saccadic peak velocity is a useful approach for presenting the pharmacological features of GABA(A)-ergic modulators. Moreover, combining the anxiogenic symptom provocation paradigm with validated neurophysiological and neuropsychological biomarkers may provide further construct validity for the clinical effects of novel anxiolytic agents. In addition, the observed drug effects on serum prolactin levels support the use of serum prolactin levels as a complementary neuroendocrine biomarker to further validate the pharmacodynamic measurements used during the clinical pharmacological study of novel anxiolytic agents.
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32
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Weir CJ, Mitchell SJ, Lambert JJ. Role of GABAA receptor subtypes in the behavioural effects of intravenous general anaesthetics. Br J Anaesth 2019; 119:i167-i175. [PMID: 29161398 DOI: 10.1093/bja/aex369] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Since the introduction of general anaesthetics into clinical practice, researchers have been mystified as to how these chemically disparate drugs act to produce their dramatic effects on central nervous system function and behaviour. Scientific advances, particularly during the last 25 years, have now begun to reveal the molecular mechanisms underpinning their behavioural effects. For certain i.v. general anaesthetics, such as etomidate and propofol, a persuasive case can now be made that the GABAA receptor, a major inhibitory receptor in the mammalian central nervous system, is an important target. Advances in molecular pharmacology and in genetic manipulation of rodent genes reveal that different subtypes of the GABAA receptor are responsible for mediating particular aspects of the anaesthetic behavioural repertoire. Such studies provide a better understanding of the neuronal circuitry involved in the various anaesthetic-induced behaviours and, in the future, may result in the development of novel therapeutics with a reduced propensity for side-effects.
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Affiliation(s)
- C J Weir
- Institute of Academic Anaesthesia
| | - S J Mitchell
- Division of Neuroscience, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
| | - J J Lambert
- Division of Neuroscience, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
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Masiulis S, Desai R, Uchański T, Serna Martin I, Laverty D, Karia D, Malinauskas T, Zivanov J, Pardon E, Kotecha A, Steyaert J, Miller KW, Aricescu AR. GABA A receptor signalling mechanisms revealed by structural pharmacology. Nature 2019; 565:454-459. [PMID: 30602790 PMCID: PMC6370056 DOI: 10.1038/s41586-018-0832-5] [Citation(s) in RCA: 333] [Impact Index Per Article: 66.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 11/23/2018] [Indexed: 01/02/2023]
Abstract
Type-A γ-aminobutyric (GABAA) receptors are ligand-gated chloride channels with a very rich pharmacology. Some of their modulators, including benzodiazepines and general anaesthetics, are among the most successful drugs in clinical use and are common substances of abuse. Without reliable structural data, the mechanistic basis for the pharmacological modulation of GABAA receptors remains largely unknown. Here we report several high-resolution cryo-electron microscopy structures in which the full-length human α1β3γ2L GABAA receptor in lipid nanodiscs is bound to the channel-blocker picrotoxin, the competitive antagonist bicuculline, the agonist GABA (γ-aminobutyric acid), and the classical benzodiazepines alprazolam and diazepam. We describe the binding modes and mechanistic effects of these ligands, the closed and desensitized states of the GABAA receptor gating cycle, and the basis for allosteric coupling between the extracellular, agonist-binding region and the transmembrane, pore-forming region. This work provides a structural framework in which to integrate previous physiology and pharmacology research and a rational basis for the development of GABAA receptor modulators.
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Affiliation(s)
- Simonas Masiulis
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK.
| | - Rooma Desai
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Tomasz Uchański
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Itziar Serna Martin
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Duncan Laverty
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Dimple Karia
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Tomas Malinauskas
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Jasenko Zivanov
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Els Pardon
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Abhay Kotecha
- Materials and Structural Analysis, Thermo Fisher Scientific, Eindhoven, The Netherlands
| | - Jan Steyaert
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Keith W Miller
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
| | - A Radu Aricescu
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK.
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK.
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Probing the molecular basis for affinity/potency- and efficacy-based subtype-selectivity exhibited by benzodiazepine-site modulators at GABAA receptors. Biochem Pharmacol 2018; 158:339-358. [DOI: 10.1016/j.bcp.2018.08.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 08/14/2018] [Indexed: 12/20/2022]
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Moody OA, Jenkins A. The role of loops B and C in determining the potentiation of GABA A receptors by midazolam. Pharmacol Res Perspect 2018; 6:e00433. [PMID: 30459951 PMCID: PMC6234229 DOI: 10.1002/prp2.433] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 07/19/2018] [Accepted: 07/21/2018] [Indexed: 12/31/2022] Open
Abstract
Many benzodiazepines are positive allosteric modulators (PAMs) of GABAA receptors that cause sedation, hypnosis, and anxiolysis. Benzodiazepines bind GABAA receptors at the extracellular interface of the α and γ subunits. Within the α subunit, the benzodiazepine binding site is defined by three highly conserved structural loops, loops A-C. Although previous mutagenesis studies have identified His102 in Loop A as important for benzodiazepine modulation of GABAA receptors, the functional roles of many of the other conserved residues in loops A-C remain incompletely understood. In this study, we made single mutations in loops A-C of the benzodiazepine binding-site across all six α subunits. We used whole-cell patch clamp recording to measure the functional effects of these mutations on midazolam potentiation. The results showed that mutating the threonine in loop B and serine in loop C (Thr163 and S206 in human α1) did not abolish the receptors' responsiveness to midazolam, as the α1(H102R) mutation did. The loop C mutations exhibited a novel array of α-isoform specific effects on midazolam potentiation. The α3(S230I) and α5(S209I) mutations had the largest effect on midazolam potentiation, increasing the efficacy of midazolam. Novel benzodiazepines targeting loop C may represent a future direction for designing new drugs that specifically alter the activity of α3- and α5-containing GABAA receptors.
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Affiliation(s)
- Olivia A. Moody
- Neuroscience ProgramGraduate Division of Biological and Biomedical SciencesLaney Graduate SchoolEmory UniversityAtlantaGeorgia
| | - Andrew Jenkins
- Departments of Anesthesiology & PharmacologyEmory UniversityAtlantaGeorgia
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TP003 is a non-selective benzodiazepine site agonist that induces anxiolysis via α2GABAA receptors. Neuropharmacology 2018; 143:71-78. [DOI: 10.1016/j.neuropharm.2018.09.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 07/27/2018] [Accepted: 09/17/2018] [Indexed: 01/09/2023]
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37
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Gravielle MC. Regulation of GABAA receptors by prolonged exposure to endogenous and exogenous ligands. Neurochem Int 2018; 118:96-104. [DOI: 10.1016/j.neuint.2018.05.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 05/22/2018] [Accepted: 05/30/2018] [Indexed: 02/08/2023]
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38
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Zhu S, Noviello CM, Teng J, Walsh RM, Kim JJ, Hibbs RE. Structure of a human synaptic GABA A receptor. Nature 2018; 559:67-72. [PMID: 29950725 PMCID: PMC6220708 DOI: 10.1038/s41586-018-0255-3] [Citation(s) in RCA: 325] [Impact Index Per Article: 54.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 05/17/2018] [Indexed: 11/08/2022]
Abstract
Fast inhibitory neurotransmission in the brain is principally mediated by the neurotransmitter GABA (γ-aminobutyric acid) and its synaptic target, the type A GABA receptor (GABAA receptor). Dysfunction of this receptor results in neurological disorders and mental illnesses including epilepsy, anxiety and insomnia. The GABAA receptor is also a prolific target for therapeutic, illicit and recreational drugs, including benzodiazepines, barbiturates, anaesthetics and ethanol. Here we present high-resolution cryo-electron microscopy structures of the human α1β2γ2 GABAA receptor, the predominant isoform in the adult brain, in complex with GABA and the benzodiazepine site antagonist flumazenil, the first-line clinical treatment for benzodiazepine overdose. The receptor architecture reveals unique heteromeric interactions for this important class of inhibitory neurotransmitter receptor. This work provides a template for understanding receptor modulation by GABA and benzodiazepines, and will assist rational approaches to therapeutic targeting of this receptor for neurological disorders and mental illness.
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Affiliation(s)
- Shaotong Zhu
- Departments of Neuroscience and Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Colleen M Noviello
- Departments of Neuroscience and Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jinfeng Teng
- Departments of Neuroscience and Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Richard M Walsh
- Departments of Neuroscience and Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jeong Joo Kim
- Departments of Neuroscience and Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Ryan E Hibbs
- Departments of Neuroscience and Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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39
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Pflanz NC, Daszkowski AW, Cornelison GL, Trudell JR, Mihic SJ. An intersubunit electrostatic interaction in the GABA A receptor facilitates its responses to benzodiazepines. J Biol Chem 2018; 293:8264-8274. [PMID: 29622679 DOI: 10.1074/jbc.ra118.002128] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 04/04/2018] [Indexed: 02/01/2023] Open
Abstract
Benzodiazepines are positive allosteric modulators of the GABAA receptor (GABAAR), acting at the α-γ subunit interface to enhance GABAAR function. GABA or benzodiazepine binding induces distinct conformational changes in the GABAAR. The molecular rearrangements in the GABAAR following benzodiazepine binding remain to be fully elucidated. Using two molecular models of the GABAAR, we identified electrostatic interactions between specific amino acids at the α-γ subunit interface that were broken by, or formed after, benzodiazepine binding. Using two-electrode voltage clamp electrophysiology in Xenopus laevis oocytes, we investigated these interactions by substituting one or both amino acids of each potential pair. We found that Lys104 in the α1 subunit forms an electrostatic bond with Asp75 of the γ2 subunit after benzodiazepine binding and that this bond stabilizes the positively modified state of the receptor. Substitution of these two residues to cysteine and subsequent covalent linkage between them increased the receptor's sensitivity to low GABA concentrations and decreased its response to benzodiazepines, producing a GABAAR that resembles a benzodiazepine-bound WT GABAAR. Breaking this bond restored sensitivity to GABA to WT levels and increased the receptor's response to benzodiazepines. The α1 Lys104 and γ2 Asp75 interaction did not play a role in ethanol or neurosteroid modulation of GABAAR, suggesting that different modulators induce different conformational changes in the receptor. These findings may help explain the additive or synergistic effects of modulators acting at the GABAAR.
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Affiliation(s)
- Natasha C Pflanz
- Department of Neuroscience, Division of Pharmacology and Toxicology, Waggoner Center for Alcohol and Addiction Research, Institutes for Neuroscience and Cell and Molecular Biology, University of Texas, Austin, Texas 78712
| | - Anna W Daszkowski
- Department of Neuroscience, Division of Pharmacology and Toxicology, Waggoner Center for Alcohol and Addiction Research, Institutes for Neuroscience and Cell and Molecular Biology, University of Texas, Austin, Texas 78712
| | - Garrett L Cornelison
- Department of Neuroscience, Division of Pharmacology and Toxicology, Waggoner Center for Alcohol and Addiction Research, Institutes for Neuroscience and Cell and Molecular Biology, University of Texas, Austin, Texas 78712
| | - James R Trudell
- Department of Anesthesia, Stanford University School of Medicine, Stanford, California 94305
| | - S John Mihic
- Department of Neuroscience, Division of Pharmacology and Toxicology, Waggoner Center for Alcohol and Addiction Research, Institutes for Neuroscience and Cell and Molecular Biology, University of Texas, Austin, Texas 78712.
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40
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Wongsamitkul N, Maldifassi MC, Simeone X, Baur R, Ernst M, Sigel E. α subunits in GABA A receptors are dispensable for GABA and diazepam action. Sci Rep 2017; 7:15498. [PMID: 29138471 PMCID: PMC5686171 DOI: 10.1038/s41598-017-15628-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 10/31/2017] [Indexed: 11/10/2022] Open
Abstract
The major isoform of the GABAA receptor is α1β2γ2. The binding sites for the agonist GABA are located at the β2+/α1− subunit interfaces and the modulatory site for benzodiazepines at α1+/γ2−. In the absence of α1 subunits, a receptor was formed that was gated by GABA and modulated by diazepam similarly. This indicates that alternative subunits can take over the role of the α1 subunits. Point mutations were introduced in β2 or γ2 subunits at positions homologous to α1− benzodiazepine binding and GABA binding positions, respectively. From this mutation work we conclude that the site for GABA is located at a β2+/β2− subunit interface and that the diazepam site is located at the β2+/γ2− subunit interface. Computational docking leads to a structural hypothesis attributing this non-canonical interaction to a binding mode nearly identical with the one at the α1+/γ2− interface. Thus, the β2 subunit can take over the role of the α1 subunit for the formation of both sites, its minus side for the GABA binding site and its plus side for the diazepam binding site.
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Affiliation(s)
- Nisa Wongsamitkul
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Maria C Maldifassi
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland.,Centro Interdisciplinario de Neurociencia de Valparaíso. Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Xenia Simeone
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Roland Baur
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Margot Ernst
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Erwin Sigel
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland.
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41
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Martinez Botella G, Salituro FG, Harrison BL, Beresis RT, Bai Z, Blanco MJ, Belfort GM, Dai J, Loya CM, Ackley MA, Althaus AL, Grossman SJ, Hoffmann E, Doherty JJ, Robichaud AJ. Neuroactive Steroids. 2. 3α-Hydroxy-3β-methyl-21-(4-cyano-1H-pyrazol-1'-yl)-19-nor-5β-pregnan-20-one (SAGE-217): A Clinical Next Generation Neuroactive Steroid Positive Allosteric Modulator of the (γ-Aminobutyric Acid) A Receptor. J Med Chem 2017; 60:7810-7819. [PMID: 28753313 DOI: 10.1021/acs.jmedchem.7b00846] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Certain classes of neuroactive steroids (NASs) are positive allosteric modulators (PAM) of synaptic and extrasynaptic GABAA receptors. Herein, we report new SAR insights in a series of 5β-nor-19-pregnan-20-one analogues bearing substituted pyrazoles and triazoles at C-21, culminating in the discovery of 3α-hydroxy-3β-methyl-21-(4-cyano-1H-pyrazol-1'-yl)-19-nor-5β-pregnan-20-one (SAGE-217, 3), a potent GABAA receptor modulator at both synaptic and extrasynaptic receptor subtypes, with excellent oral DMPK properties. Compound 3 has completed a phase 1 single ascending dose (SAD) and multiple ascending dose (MAD) clinical trial and is currently being studied in parallel phase 2 clinical trials for the treatment of postpartum depression (PPD), major depressive disorder (MDD), and essential tremor (ET).
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Affiliation(s)
| | - Francesco G Salituro
- Sage Therapeutics, Inc. 215 First Street, Cambridge, Massachusetts 02142, United States
| | - Boyd L Harrison
- Sage Therapeutics, Inc. 215 First Street, Cambridge, Massachusetts 02142, United States
| | | | - Zhu Bai
- WuXi AppTec , 288 Fute Zhong Road, Shanghai 200131, China
| | - Maria-Jesus Blanco
- Sage Therapeutics, Inc. 215 First Street, Cambridge, Massachusetts 02142, United States
| | - Gabriel M Belfort
- Sage Therapeutics, Inc. 215 First Street, Cambridge, Massachusetts 02142, United States
| | - Jing Dai
- Sage Therapeutics, Inc. 215 First Street, Cambridge, Massachusetts 02142, United States
| | - Carlos M Loya
- Sage Therapeutics, Inc. 215 First Street, Cambridge, Massachusetts 02142, United States
| | - Michael A Ackley
- Sage Therapeutics, Inc. 215 First Street, Cambridge, Massachusetts 02142, United States
| | - Alison L Althaus
- Sage Therapeutics, Inc. 215 First Street, Cambridge, Massachusetts 02142, United States
| | - Scott J Grossman
- Sage Therapeutics, Inc. 215 First Street, Cambridge, Massachusetts 02142, United States
| | - Ethan Hoffmann
- Sage Therapeutics, Inc. 215 First Street, Cambridge, Massachusetts 02142, United States
| | - James J Doherty
- Sage Therapeutics, Inc. 215 First Street, Cambridge, Massachusetts 02142, United States
| | - Albert J Robichaud
- Sage Therapeutics, Inc. 215 First Street, Cambridge, Massachusetts 02142, United States
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42
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Hammond RS, Althaus AL, Ackley MA, Maciag C, Martinez Botella G, Salituro FG, Robichaud AJ, Doherty JJ. Anticonvulsant profile of the neuroactive steroid, SGE-516, in animal models. Epilepsy Res 2017; 134:16-25. [PMID: 28521115 DOI: 10.1016/j.eplepsyres.2017.05.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 04/21/2017] [Accepted: 05/03/2017] [Indexed: 12/18/2022]
Abstract
Despite the availability of multiple antiepileptic drugs (AED), failure to adequately control seizures is a challenge for approximately one third of epilepsy patients, and new therapies with a differentiated mechanism of action are needed. The neuroactive steroid, SGE-516, is a positive allosteric modulator of both gamma- and delta-containing GABAA receptors. This broad GABAA receptor activity differentiates neuroactive steroids like SGE-516 from benzodiazepines, a class of anticonvulsants which have been shown in vitro to selectively target gamma-subunit containing GABAA receptors. As a neuroactive steroid, SGE-516 has pharmacokinetic properties that are intended to allow for chronic oral dosing. We investigated the anticonvulsant activity of SGE-516 across numerous in vitro and in vivo models of seizure activity. SGE-516 dose-dependently reduced neuronal firing rates and epileptiform activity in vitro. In mice, SGE-516 protected against acute seizures in the PTZ-induced chemo-convulsant seizure model and the 6Hz psychomotor seizure model. In addition, SGE-516 demonstrated anticonvulsant activity in the mouse corneal kindling model. These data suggest that SGE-516 may have potential for development as a novel oral AED for the treatment of refractory seizures.
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43
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Dumitru I, Neitz A, Alfonso J, Monyer H. Diazepam Binding Inhibitor Promotes Stem Cell Expansion Controlling Environment-Dependent Neurogenesis. Neuron 2017; 94:125-137.e5. [PMID: 28343864 DOI: 10.1016/j.neuron.2017.03.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 01/06/2017] [Accepted: 03/01/2017] [Indexed: 12/31/2022]
Abstract
Plasticity of adult neurogenesis supports adaptation to environmental changes. The identification of molecular mediators that signal these changes to neural progenitors in the niche has remained elusive. Here we report that diazepam binding inhibitor (DBI) is crucial in supporting an adaptive mechanism in response to changes in the environment. We provide evidence that DBI is expressed in stem cells in all neurogenic niches of the postnatal brain. Focusing on the hippocampal subgranular zone (SGZ) and employing multiple genetic manipulations in vivo, we demonstrate that DBI regulates the balance between preserving the stem cell pool and neurogenesis. Specifically, DBI dampens GABA activity in stem cells, thereby sustaining the proproliferative effect of physical exercise and enriched environment. Our data lend credence to the notion that the modulatory effect of DBI constitutes a general mechanism that regulates postnatal neurogenesis.
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Affiliation(s)
- Ionut Dumitru
- Department of Clinical Neurobiology at the German Cancer Research Center (DKFZ) and the Medical Faculty of the Heidelberg University, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Angela Neitz
- Department of Clinical Neurobiology at the German Cancer Research Center (DKFZ) and the Medical Faculty of the Heidelberg University, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Julieta Alfonso
- Department of Clinical Neurobiology at the German Cancer Research Center (DKFZ) and the Medical Faculty of the Heidelberg University, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
| | - Hannah Monyer
- Department of Clinical Neurobiology at the German Cancer Research Center (DKFZ) and the Medical Faculty of the Heidelberg University, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
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44
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Chua HC, Chebib M. GABA A Receptors and the Diversity in their Structure and Pharmacology. ADVANCES IN PHARMACOLOGY 2017; 79:1-34. [DOI: 10.1016/bs.apha.2017.03.003] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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45
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Wisden W. A Tribute to Peter H Seeburg (1944-2016): A Founding Father of Molecular Neurobiology. Front Mol Neurosci 2016; 9:133. [PMID: 27965536 PMCID: PMC5126100 DOI: 10.3389/fnmol.2016.00133] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 11/15/2016] [Indexed: 11/25/2022] Open
Affiliation(s)
- William Wisden
- Department of Life Sciences and Centre for Neurotechnology, Imperial College London London, UK
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46
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Chagraoui A, Skiba M, Thuillez C, Thibaut F. To what extent is it possible to dissociate the anxiolytic and sedative/hypnotic properties of GABAA receptors modulators? Prog Neuropsychopharmacol Biol Psychiatry 2016; 71:189-202. [PMID: 27495357 DOI: 10.1016/j.pnpbp.2016.08.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 07/21/2016] [Accepted: 08/01/2016] [Indexed: 01/16/2023]
Abstract
The relatively common view indicates a possible dissociation between the anxiolytic and sedative/hypnotic properties of benzodiazepines (BZs). Indeed, GABAA receptor (GABAAR) subtypes have specific cerebral distribution in distinct neural circuits. Thus, GABAAR subtype-selective drugs may be expected to perform distinct functions. However, standard behavioral test assays provide limited direction towards highlighting new action mechanisms of ligands targeting GABAARs. Automated behavioral tests, lack sensitivity as some behavioral characteristics or subtle behavioral changes of drug effects or that are not considered in the overall analysis (Ohl et al., 2001) and observation-based analyses are not always performed. In addition, despite the use of genetically engineered mice, any possible dissociation between the anxiolytic and sedative properties of BZs remains controversial. Moreover, the involvement the different subtypes of GABAAR subtypes in the anxious behavior and the mechanism of action of anxiolytic agents remains unclear since there has been little success in the pharmacological investigations so far. This raises the question of the involvement of the different subunits in anxiolytic-like and/or sedative effects; and the actual implication of these subunits, particularly, α-subunits in the modulation of sedation and/or anxiety-related disorders. This present review was prompted by several conflicting studies on the degree of involvement of these subunits in anxiolytic-like and/or sedative effects. To this end, we explored the GABAergic system, particularly, the role of different subunits containing synaptic GABAARs. We report herein the targeting gene encoding the different subunits and their contribution in anxiolytic-like and/or sedative actions, as well as, the mechanism underlying tolerance to BZs.
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Affiliation(s)
- A Chagraoui
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Institute for Research and Innovation in Biomedecine, Normandy University, France; Department of Medical Biochemistry, Rouen University Hospital, Rouen, France.
| | - M Skiba
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Institute for Research and Innovation in Biomedecine, Normandy University, France
| | - C Thuillez
- Department of Pharmacology, Rouen University Hospital, Rouen, and INSERM U1096, Laboratory of New Pharmacological Targets for Endothelial Protection and Heart Failure, Institute for Research and Innovation in Biomedicine, Normandy University, France
| | - F Thibaut
- Department of Psychiatry, University Hospital Cochin (site Tarnier), University of Paris-Descartes and INSERM U 894 Laboratory of Psychiatry and Neurosciences, Paris, France
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47
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Newman EL, Gunner G, Huynh P, Gachette D, Moss S, Smart T, Rudolph U, DeBold JF, Miczek KA. Effects of Gabra2 Point Mutations on Alcohol Intake: Increased Binge-Like and Blunted Chronic Drinking by Mice. Alcohol Clin Exp Res 2016; 40:2445-2455. [PMID: 27717041 PMCID: PMC5073020 DOI: 10.1111/acer.13215] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 08/11/2016] [Indexed: 01/08/2023]
Abstract
BACKGROUND Alcohol use disorders are associated with single-nucleotide polymorphisms in GABRA2, the gene encoding the GABAA receptor α2-subunit in humans. Deficient GABAergic functioning is linked to impulse control disorders, intermittent explosive disorder, and to drug abuse and dependence, yet it remains unclear whether α2-containing GABAA receptor sensitivity to endogenous ligands is involved in excessive alcohol drinking. METHODS Male wild-type (Wt) C57BL/6J and point-mutated mice rendered insensitive to GABAergic modulation by benzodiazepines (BZD; H101R), allopregnanolone (ALLO) or tetrahydrodeoxycorticosterone (THDOC; Q241M), or high concentrations of ethanol (EtOH) (S270H/L277A) at α2-containing GABAA receptors were assessed for their binge-like, moderate, or escalated chronic drinking using drinking in the dark, continuous access (CA) and intermittent access (IA) to alcohol protocols, respectively. Social approach by mutant and Wt mice in forced alcohol abstinence was compared to approach by EtOH-naïve controls. Social deficits in forced abstinence were treated with allopregnanolone (0, 3.0, 10.0 mg/kg, intraperitoneal [i.p.]) or midazolam (0, 0.56, 1.0 mg/kg, i.p.). RESULTS Mice with BZD-insensitive α2-containing GABAA receptors (H101R) escalated their binge-like drinking. Mutants harboring the Q241M point substitution in Gabra2 showed blunted chronic intake in the CA and IA protocols. S270H/L277A mutants consumed excessive amounts of alcohol but, unlike wild-types, they did not show forced abstinence-induced social deficits. CONCLUSIONS These findings suggest a role for: (i) H101 in species-typical binge-like drinking, (ii) Q241 in escalated chronic drinking, and (iii) S270 and/or L277 in the development of forced abstinence-associated social deficits. Clinical findings report reduced BZD-binding sites in the cortex of dependent patients; the present findings suggest a specific role for BZD-sensitive α2-containing receptors. In addition, amino acid residue 241 in Gabra2 is necessary for positive modulation and activation of GABAA receptors by ALLO and THDOC; we postulate that neurosteroid action on α2-containing receptor may be necessary for escalated chronic EtOH intake.
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Affiliation(s)
| | | | | | | | | | - Trevor Smart
- Dept. of Neuroscience, Physiology and Pharmacology, University College London
| | - Uwe Rudolph
- Laboratory of Genetic Neuropharmacology, McLean Hospital,Dept. of Psychiatry, Harvard Medical School
| | | | - Klaus A. Miczek
- Dept. of Psychology, Tufts University,Dept. of Neuroscience, Tufts University
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48
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Learning Modulate Down Regulation of GABAAα1 Receptors in Amygdala and Cerebellum of Rats Exposed to Bisphenol A. ARCHIVES OF NEUROSCIENCE 2016. [DOI: 10.5812/archneurosci.37297] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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49
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Yang H, Woo J, Pae AN, Um MY, Cho NC, Park KD, Yoon M, Kim J, Lee CJ, Cho S. α-Pinene, a Major Constituent of Pine Tree Oils, Enhances Non-Rapid Eye Movement Sleep in Mice through GABAA-benzodiazepine Receptors. Mol Pharmacol 2016; 90:530-539. [DOI: 10.1124/mol.116.105080] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 08/19/2016] [Indexed: 11/22/2022] Open
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50
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New and mild method for the synthesis of alprazolam and diazepam and computational study of their binding mode to GABAA receptor. Med Chem Res 2016. [DOI: 10.1007/s00044-016-1585-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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