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Kasaragod VB, Malinauskas T, Wahid AA, Lengyel J, Knoflach F, Hardwick SW, Jones CF, Chen WN, Lucas X, El Omari K, Chirgadze DY, Aricescu AR, Cecere G, Hernandez MC, Miller PS. The molecular basis of drug selectivity for α5 subunit-containing GABA A receptors. Nat Struct Mol Biol 2023; 30:1936-1946. [PMID: 37903907 PMCID: PMC10716045 DOI: 10.1038/s41594-023-01133-1] [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: 02/28/2023] [Accepted: 09/20/2023] [Indexed: 11/01/2023]
Abstract
α5 subunit-containing γ-aminobutyric acid type A (GABAA) receptors represent a promising drug target for neurological and neuropsychiatric disorders. Altered expression and function contributes to neurodevelopmental disorders such as Dup15q and Angelman syndromes, developmental epilepsy and autism. Effective drug action without side effects is dependent on both α5-subtype selectivity and the strength of the positive or negative allosteric modulation (PAM or NAM). Here we solve structures of drugs bound to the α5 subunit. These define the molecular basis of binding and α5 selectivity of the β-carboline, methyl 6,7-dimethoxy-4-ethyl-β-carboline-3-carboxylate (DMCM), type II benzodiazepine NAMs, and a series of isoxazole NAMs and PAMs. For the isoxazole series, each molecule appears as an 'upper' and 'lower' moiety in the pocket. Structural data and radioligand binding data reveal a positional displacement of the upper moiety containing the isoxazole between the NAMs and PAMs. Using a hybrid molecule we directly measure the functional contribution of the upper moiety to NAM versus PAM activity. Overall, these structures provide a framework by which to understand distinct modulator binding modes and their basis of α5-subtype selectivity, appreciate structure-activity relationships, and empower future structure-based drug design campaigns.
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Affiliation(s)
- Vikram Babu Kasaragod
- Department of Pharmacology, University of Cambridge, Cambridge, UK
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Tomas Malinauskas
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Ayla A Wahid
- Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Judith Lengyel
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases, Roche Innovation Center, Basel, Switzerland
| | - Frederic Knoflach
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases, Roche Innovation Center, Basel, Switzerland
| | - Steven W Hardwick
- CryoEM Facility, Department of Biochemistry, University of Cambridge, Cambridge, UK
| | | | - Wan-Na Chen
- Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Xavier Lucas
- Roche Pharma Research and Early Development, Therapeutic Modalities, Roche Innovation Center, Basel, Switzerland
| | - Kamel El Omari
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Dimitri Y Chirgadze
- CryoEM Facility, Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - A Radu Aricescu
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Giuseppe Cecere
- Roche Pharma Research and Early Development, Therapeutic Modalities, Roche Innovation Center, Basel, Switzerland
| | - Maria-Clemencia Hernandez
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases, Roche Innovation Center, Basel, Switzerland.
| | - Paul S Miller
- Department of Pharmacology, University of Cambridge, Cambridge, UK.
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Wyroślak M, Dobrzański G, Mozrzymas JW. Bidirectional plasticity of GABAergic tonic inhibition in hippocampal somatostatin- and parvalbumin-containing interneurons. Front Cell Neurosci 2023; 17:1193383. [PMID: 37448697 PMCID: PMC10336215 DOI: 10.3389/fncel.2023.1193383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 06/05/2023] [Indexed: 07/15/2023] Open
Abstract
GABAA receptors present in extrasynaptic areas mediate tonic inhibition in hippocampal neurons regulating the performance of neural networks. In this study, we investigated the effect of NMDA-induced plasticity on tonic inhibition in somatostatin- and parvalbumin-containing interneurons. Using pharmacological methods and transgenic mice (SST-Cre/PV-Cre x Ai14), we induced the plasticity of GABAergic transmission in somatostatin- and parvalbumin-containing interneurons by a brief (3 min) application of NMDA. In the whole-cell patch-clamp configuration, we measured tonic currents enhanced by specific agonists (etomidate or gaboxadol). Furthermore, in both the control and NMDA-treated groups, we examined to what extent these changes depend on the regulation of distinct subtypes of GABAA receptors. Tonic conductance in the somatostatin-containing (SST+) interneurons is enhanced after NMDA application, and the observed effect is associated with an increased content of α5-containing GABAARs. Both fast-spiking and non-fast-spiking parvalbumin-positive (PV+) cells showed a reduction of tonic inhibition after plasticity induction. This effect was accompanied in both PV+ interneuron types by a strongly reduced proportion of δ-subunit-containing GABAARs and a relatively small increase in currents mediated by α5-containing GABAARs. Both somatostatin- and parvalbumin-containing interneurons show cell type-dependent and opposite sign plasticity of tonic inhibition. The underlying mechanisms depend on the cell-specific balance of plastic changes in the contents of α5 and δ subunit-containing GABAARs.
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Affiliation(s)
- Marcin Wyroślak
- Department of Biophysics and Neuroscience, Wroclaw Medical University, Wrocław, Poland
| | | | - Jerzy W. Mozrzymas
- Department of Biophysics and Neuroscience, Wroclaw Medical University, Wrocław, Poland
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3
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The Case for Clinical Trials with Novel GABAergic Drugs in Diabetes Mellitus and Obesity. Life (Basel) 2022; 12:life12020322. [PMID: 35207609 PMCID: PMC8876029 DOI: 10.3390/life12020322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 02/09/2022] [Accepted: 02/16/2022] [Indexed: 11/17/2022] Open
Abstract
Obesity and diabetes mellitus have become the surprising menaces of relative economic well-being worldwide. Gamma amino butyric acid (GABA) has a prominent role in the control of blood glucose, energy homeostasis as well as food intake at several levels of regulation. The effects of GABA in the body are exerted through ionotropic GABAA and metabotropic GABAB receptors. This treatise will focus on the pharmacologic targeting of GABAA receptors to reap beneficial therapeutic effects in diabetes mellitus and obesity. A new crop of drugs selectively targeting GABAA receptors has been under investigation for efficacy in stroke recovery and cognitive deficits associated with schizophrenia. Although these trials have produced mixed outcomes the compounds are safe to use in humans. Preclinical evidence is summarized here to support the rationale of testing some of these compounds in diabetic patients receiving insulin in order to achieve better control of blood glucose levels and to combat the decline of cognitive performance. Potential therapeutic benefits could be achieved (i) By resetting the hypoglycemic counter-regulatory response; (ii) Through trophic actions on pancreatic islets, (iii) By the mobilization of antioxidant defence mechanisms in the brain. Furthermore, preclinical proof-of-concept work, as well as clinical trials that apply the novel GABAA compounds in eating disorders, e.g., olanzapine-induced weight-gain, also appear warranted.
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Santrač A, Batinić B, Stamenić TT, Aranđelović J, Sharmin D, Knutson DE, Cook JM, Savić MM. Positive modulation of α5GABAA receptors leads to dichotomous effects in rats on memory pattern and GABRA5 expression in prefrontal cortex and hippocampus. Behav Brain Res 2022; 416:113578. [PMID: 34508769 DOI: 10.1016/j.bbr.2021.113578] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Revised: 08/22/2021] [Accepted: 09/06/2021] [Indexed: 01/04/2023]
Abstract
Positive allosteric modulators (PAMs) of α5GABAA receptors (α5GABAARs) are emerging as potential therapeutics for a range of neuropsychiatric disorders. However, their role in memory processing of healthy animals is not sufficiently examined. We tested the effects of MP-III-022 (1 mg/kg, 2.5 mg/kg and 10 mg/kg), a PAM known to be selective for α5GABAARs and devoid of prominent side-effects, in different behavioral paradigms (Morris water maze, novel object recognition test and social novelty discrimination) and on GABRA5 expression in Wistar rats, 30 min and 24 h after intraperitoneal treatment administration. The lowest dose tested worsened short-term object memory. The same dose, administered two times in a span of 24 h, improved spatial and impaired object and, at a trend level, social memory. The highest dose had a detrimental effect on all types of long-term memory (object memory at a trend level) and short-term spatial memory, but improved short-term object and social memory. Distinct sets of expression changes were detected in both prefrontal cortex and two regions of the hippocampus, but the latter ones could be assessed as more consequential. An increase of GABRA5 mRNA in CA2 occurred in parallel with improvement of object and social, but impairment of spatial memory, while the opposite happened with a trend level change in CA1. Our study demonstrates the variability of the roles of the α5GABAAR based on its level of expression and localization, in dependence on the type and protocol of cognitive tasks, as well as the respective timing of pharmacological modulation and testing.
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Affiliation(s)
- Anja Santrač
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia
| | - Bojan Batinić
- Department of Physiology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia
| | - Tamara Timić Stamenić
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia
| | - Jovana Aranđelović
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia
| | - Dishary Sharmin
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee and the Milwaukee Institute of Drug Discovery, P.O.Box 413, Milwaukee, WI 53201, USA
| | - Daniel E Knutson
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee and the Milwaukee Institute of Drug Discovery, P.O.Box 413, Milwaukee, WI 53201, USA
| | - James M Cook
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee and the Milwaukee Institute of Drug Discovery, P.O.Box 413, Milwaukee, WI 53201, USA
| | - Miroslav M Savić
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia.
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Yuan C, Gao A, Xu Q, Zhang B, Xue R, Dou Y, Yu C. A multi-dosing regimen to enhance the spatial memory of normal rats with α5-containing GABA A receptor negative allosteric modulator L-655,708. Psychopharmacology (Berl) 2021; 238:3375-3389. [PMID: 34389882 DOI: 10.1007/s00213-021-05951-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Accepted: 08/03/2021] [Indexed: 01/20/2023]
Abstract
RATIONALE AND OBJECTIVES The reported inconsistent effects of negative allosteric modulators of α5-containing GABAA receptors on learning and memory may be attributed to receptor selectivity, effective plasma concentration maintenance, and administration time. This study aimed to compare the effects of L-655,708 administered by single-dosing regimen versus multi-dosing regimen on spatial memory, signaling molecules, and brain functional connectivity. METHODS After comparing the maintenance time of the effective plasma concentration of L-655,708 between multi-dosing and single-dosing regimens, we further compared the effects of the administration of the two regimens at different phases (before-learning, during-learning, and before-probe) of the Morris water maze (MWM) test on the performance of learning and memory and the levels of signaling molecules related to learning and memory in hippocampal tissues. Functional connectivity analyses between hippocampal and cortical regions were performed to further clarify the effects of the multi-dosing regimen. RESULTS The multi-dosing regimen could maintain the effective plasma concentration of L-655,708 much longer than the single-dosing regimen. Only the multi-dosing regimen for L-655,708 administration during the learning period led to significant improvement in spatial memory in the MWM test and increases in levels of glutamate receptors and phosphorylated signaling molecules (p-PKAα, p-CaMKII, and p-CREB-1). Compared with the vehicle control, the multi-dosing regimen increased the functional connectivity of the left hippocampal CA1 with cingulate and motor cortices. CONCLUSIONS A multi-dosing regimen for L-655,708 administered during the learning period is an effective strategy to improve spatial memory, increase signaling molecule levels, and enhance the functional connectivity of the hippocampus.
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Affiliation(s)
- Congcong Yuan
- Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, 300052, People's Republic of China
| | - An Gao
- Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, 300052, People's Republic of China
| | - Qiang Xu
- Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, 300052, People's Republic of China
| | - Beibei Zhang
- Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, 300052, People's Republic of China
| | - Rui Xue
- Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, 300052, People's Republic of China
| | - Yan Dou
- Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, 300052, People's Republic of China.
| | - Chunshui Yu
- Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, 300052, People's Republic of China.
- School of Medical Imaging, Tianjin Medical University, Tianjin, 300052, People's Republic of China.
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Maksymetz J, Byun NE, Luessen DJ, Li B, Barry RL, Gore JC, Niswender CM, Lindsley CW, Joffe ME, Conn PJ. mGlu 1 potentiation enhances prelimbic somatostatin interneuron activity to rescue schizophrenia-like physiological and cognitive deficits. Cell Rep 2021; 37:109950. [PMID: 34731619 PMCID: PMC8628371 DOI: 10.1016/j.celrep.2021.109950] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 08/09/2021] [Accepted: 10/14/2021] [Indexed: 01/03/2023] Open
Abstract
Evidence for prefrontal cortical (PFC) GABAergic dysfunction is one of the most consistent findings in schizophrenia and may contribute to cognitive deficits. Recent studies suggest that the mGlu1 subtype of metabotropic glutamate receptor regulates cortical inhibition; however, understanding the mechanisms through which mGlu1 positive allosteric modulators (PAMs) regulate PFC microcircuit function and cognition is essential for advancing these potential therapeutics toward the clinic. We report a series of electrophysiology, optogenetic, pharmacological magnetic resonance imaging, and animal behavior studies demonstrating that activation of mGlu1 receptors increases inhibitory transmission in the prelimbic PFC by selective excitation of somatostatin-expressing interneurons (SST-INs). An mGlu1 PAM reverses cortical hyperactivity and concomitant cognitive deficits induced by N-methyl-d-aspartate (NMDA) receptor antagonists. Using in vivo optogenetics, we show that prelimbic SST-INs are necessary for mGlu1 PAM efficacy. Collectively, these findings suggest that mGlu1 PAMs could reverse cortical GABAergic deficits and exhibit efficacy in treating cognitive dysfunction in schizophrenia.
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Affiliation(s)
- James Maksymetz
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA
| | - Nellie E Byun
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Deborah J Luessen
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA
| | - Brianna Li
- Vanderbilt University, Nashville, TN 37232, USA
| | - Robert L Barry
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Radiology & Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - John C Gore
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Radiology & Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232, USA
| | - Colleen M Niswender
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Vanderbilt Institute for Chemical Biology, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37232, USA
| | - Craig W Lindsley
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt Institute for Chemical Biology, Vanderbilt University, Nashville, TN 37232, USA; Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA
| | - Max E Joffe
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA
| | - P Jeffrey Conn
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Vanderbilt Institute for Chemical Biology, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37232, USA.
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7
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Sparsification of AP firing in adult-born hippocampal granule cells via voltage-dependent α5-GABA A receptors. Cell Rep 2021; 37:109768. [PMID: 34610304 DOI: 10.1016/j.celrep.2021.109768] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 07/07/2021] [Accepted: 09/08/2021] [Indexed: 11/21/2022] Open
Abstract
GABA can depolarize immature neurons close to the action potential (AP) threshold in development and adult neurogenesis. Nevertheless, GABAergic synapses effectively inhibit AP firing in newborn granule cells of the adult hippocampus as early as two weeks post-mitosis. The underlying mechanisms are largely unclear. Here, we analyze GABAergic inputs in newborn hippocampal granule cells mediated by soma-targeting parvalbumin and dendrite-targeting somatostatin interneurons. Surprisingly, both interneuron subtypes activate α5-subunit-containing GABAA receptors (α5-GABAARs) in young neurons, showing a nonlinear voltage dependence with increasing conductance around the AP threshold. By contrast, in mature cells, parvalbumin interneurons mediate linear GABAergic synaptic currents lacking α5-subunits, while somatostatin interneurons continue to target nonlinear α5-GABAARs. Computational modeling shows that the voltage-dependent amplification of α5-GABAAR opening in young neurons is crucial for inhibition of AP firing to generate balanced and sparse firing activity, even with depolarized GABA reversal potential.
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8
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Nuwer JL, Brady ML, Povysheva NV, Coyne A, Jacob TC. Sustained treatment with an α5 GABA A receptor negative allosteric modulator delays excitatory circuit development while maintaining GABAergic neurotransmission. Neuropharmacology 2021; 197:108724. [PMID: 34284042 DOI: 10.1016/j.neuropharm.2021.108724] [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: 04/01/2021] [Revised: 07/01/2021] [Accepted: 07/14/2021] [Indexed: 01/02/2023]
Abstract
α5 subunit GABA type A receptor (GABAAR) preferring negative allosteric modulators (NAMs) are cognitive enhancers with antidepressant-like effects. α5-NAM success in treating mouse models of neurodevelopmental disorders with excessive inhibition have led to Phase 2 clinical trials for Down syndrome. Despite in vivo efficacy, no study has examined the effects of continued α5-NAM treatment on inhibitory and excitatory synapse plasticity to identify mechanisms of action. Here we used L-655,708, an imidazobenzodiazepine that acts as a highly selective but weak α5-NAM, to investigate the impact of sustained treatment on hippocampal neuron synapse and dendrite development. We show that 2-day pharmacological reduction of α5-GABAAR signaling from DIV12-14, when GABAARs contribute to depolarization, delays dendritic spine maturation and the NMDA receptor (NMDAR) GluN2B/GluN2A developmental shift. In contrast, α5-NAM treatment from DIV19-21, when hyperpolarizing GABAAR signaling predominates, enhances surface synaptic GluN2A while decreasing GluN2B. Despite changes in NMDAR subtype surface levels and localization, total levels of key excitatory synapse proteins were largely unchanged, and mEPSCs were unaltered. Importantly, 2-day α5-NAM treatment does not alter the total surface levels or distribution of α5-GABAARs, reduce the gephyrin inhibitory synaptic scaffold, or impair phasic or tonic inhibition. Furthermore, α5-NAM inhibition of the GABAAR tonic current in mature neurons is maintained after 2-day α5-NAM treatment, suggesting reduced tolerance liability, in contrast to other clinically relevant GABAAR-targeting drugs such as benzodiazepines. Together, these results show that α5-GABAARs contribute to dendritic spine maturation and excitatory synapse development via a NMDAR dependent mechanism without perturbing overall neuronal excitability.
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Affiliation(s)
- Jessica L Nuwer
- 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
| | - Nadya V Povysheva
- Department of Neuroscience and Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - Amanda Coyne
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, 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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9
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Basmisanil, a highly selective GABA A-α5 negative allosteric modulator: preclinical pharmacology and demonstration of functional target engagement in man. Sci Rep 2021; 11:7700. [PMID: 33833333 PMCID: PMC8032764 DOI: 10.1038/s41598-021-87307-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 03/26/2021] [Indexed: 12/21/2022] Open
Abstract
GABAA-α5 subunit-containing receptors have been shown to play a key modulatory role in cognition and represent a promising drug target for cognitive dysfunction, as well as other disorders. Here we report on the preclinical and early clinical profile of a novel GABAA-α5 selective negative allosteric modulator (NAM), basmisanil, which progressed into Phase II trials for intellectual disability in Down syndrome and cognitive impairment associated with schizophrenia. Preclinical pharmacology studies showed that basmisanil is the most selective GABAA-α5 receptor NAM described so far. Basmisanil bound to recombinant human GABAA-α5 receptors with 5 nM affinity and more than 90-fold selectivity versus α1, α2, and α3 subunit-containing receptors. Moreover, basmisanil inhibited GABA-induced currents at GABAA-α5 yet had little or no effect at the other receptor subtypes. An in vivo occupancy study in rats showed dose-dependent target engagement and was utilized to establish the plasma exposure to receptor occupancy relationship. At estimated receptor occupancies between 30 and 65% basmisanil attenuated diazepam-induced spatial learning impairment in rats (Morris water maze), improved executive function in non-human primates (object retrieval), without showing anxiogenic or proconvulsant effects in rats. During the Phase I open-label studies, basmisanil showed good safety and tolerability in healthy volunteers at maximum GABAA-α5 receptor occupancy as confirmed by PET analysis with the tracer [11C]-Ro 15-4513. An exploratory EEG study provided evidence for functional activity of basmisanil in human brain. Therefore, these preclinical and early clinical studies show that basmisanil has an ideal profile to investigate potential clinical benefits of GABAA-α5 receptor negative modulation.
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10
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Petrache AL, Khan AA, Nicholson MW, Monaco A, Kuta-Siejkowska M, Haider S, Hilton S, Jovanovic JN, Ali AB. Selective Modulation of α5 GABA A Receptors Exacerbates Aberrant Inhibition at Key Hippocampal Neuronal Circuits in APP Mouse Model of Alzheimer's Disease. Front Cell Neurosci 2020; 14:568194. [PMID: 33262690 PMCID: PMC7686552 DOI: 10.3389/fncel.2020.568194] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 09/28/2020] [Indexed: 11/13/2022] Open
Abstract
Selective negative allosteric modulators (NAMs), targeting α5 subunit-containing GABAA receptors (GABAARs) as potential therapeutic targets for disorders associated with cognitive deficits, including Alzheimer's disease (AD), continually fail clinical trials. We investigated whether this was due to the change in the expression of α5 GABAARs, consequently altering synaptic function during AD pathogenesis. Using medicinal chemistry and computational modeling, we developed aqueous soluble hybrids of 6,6-dimethyl-3-(2-hydroxyethyl) thio-1-(thiazol-2-yl)-6,7-dihydro-2-benzothiophene-4(5H)-one, that demonstrated selective binding and high negative allosteric modulation, specifically for the α5 GABAAR subtypes in constructed HEK293 stable cell-lines. Using a knock-in mouse model of AD (APP NL-F/NL-F), which expresses a mutant form of human amyloid-β (Aβ), we performed immunofluorescence studies combined with electrophysiological whole-cell recordings to investigate the effects of our key molecule, α5-SOP002 in the hippocampal CA1 region. In aged APP NL-F/NL-F mice, selective preservation of α5 GABAARs was observed in, calretinin- (CR), cholecystokinin- (CCK), somatostatin- (SST) expressing interneurons, and pyramidal cells. Previously, we reported that CR dis-inhibitory interneurons, specialized in regulating other interneurons displayed abnormally high levels of synaptic inhibition in the APP NL-F/NL-F mouse model, here we show that this excessive inhibition was "normalized" to control values with bath-applied α5-SOP002 (1 μM). However, α5-SOP002, further impaired inhibition onto CCK and pyramidal cells that were already largely compromised by exhibiting a deficit of inhibition in the AD model. In summary, using a multi-disciplinary approach, we show that exposure to α5 GABAAR NAMs may further compromise aberrant synapses in AD. We, therefore, suggest that the α5 GABAAR is not a suitable therapeutic target for the treatment of AD or other cognitive deficits due to the widespread neuronal-networks that use α5 GABAARs.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Afia B Ali
- UCL School of Pharmacy, London, United Kingdom
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11
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Lewis A, Beresford A, Chambers MS, Clark G, Hartley DC, Hirst KL, Higashino M, Kawahadara S, Nakanishi M, Saito T, Imagawa A, Habashita H, Maidment S, Macleod AM, Owens AP, Rae A, Rouse C, Wishart G. Discovery of ONO-8590580: A novel, potent and selective GABA A α 5 negative allosteric modulator for the treatment of cognitive disorders. Bioorg Med Chem Lett 2020; 30:127536. [PMID: 32898695 DOI: 10.1016/j.bmcl.2020.127536] [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: 05/11/2020] [Revised: 08/28/2020] [Accepted: 08/31/2020] [Indexed: 10/23/2022]
Abstract
The identification and SAR development of a series of negative allosteric modulators of the GABAA α5 receptor is described. This novel series of compounds was optimised to provide analogues with high GABAA α5 binding affinity, high α5 negative allosteric modulatory activity, good functional subtype selectivity and low microsomal turnover, culminating in identification of ONO-8590580.
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Affiliation(s)
- A Lewis
- Charles River Discovery Research Services, Chesterford Research Park, Little Chesterford, Essex CB10 1XL, United Kingdom
| | - A Beresford
- Charles River Discovery Research Services, Chesterford Research Park, Little Chesterford, Essex CB10 1XL, United Kingdom
| | - M S Chambers
- Charles River Discovery Research Services, Chesterford Research Park, Little Chesterford, Essex CB10 1XL, United Kingdom
| | - G Clark
- Charles River Discovery Research Services, Chesterford Research Park, Little Chesterford, Essex CB10 1XL, United Kingdom
| | - D C Hartley
- Charles River Discovery Research Services, Chesterford Research Park, Little Chesterford, Essex CB10 1XL, United Kingdom
| | - K L Hirst
- Charles River Discovery Research Services, Chesterford Research Park, Little Chesterford, Essex CB10 1XL, United Kingdom
| | - M Higashino
- Ono Pharmaceutical Co. Ltd., Minase Research Institute, Shimamoto-cho, Mishima-gun, Osaka 618-8585, Japan
| | - S Kawahadara
- Ono Pharmaceutical Co. Ltd., Minase Research Institute, Shimamoto-cho, Mishima-gun, Osaka 618-8585, Japan
| | - M Nakanishi
- Ono Pharmaceutical Co. Ltd., Minase Research Institute, Shimamoto-cho, Mishima-gun, Osaka 618-8585, Japan
| | - T Saito
- Ono Pharmaceutical Co. Ltd., Minase Research Institute, Shimamoto-cho, Mishima-gun, Osaka 618-8585, Japan
| | - A Imagawa
- Ono Pharmaceutical Co. Ltd., Minase Research Institute, Shimamoto-cho, Mishima-gun, Osaka 618-8585, Japan
| | - H Habashita
- Ono Pharmaceutical Co. Ltd., Minase Research Institute, Shimamoto-cho, Mishima-gun, Osaka 618-8585, Japan
| | - S Maidment
- Charles River Discovery Research Services, Chesterford Research Park, Little Chesterford, Essex CB10 1XL, United Kingdom
| | - A M Macleod
- Charles River Discovery Research Services, Chesterford Research Park, Little Chesterford, Essex CB10 1XL, United Kingdom
| | - A P Owens
- Charles River Discovery Research Services, Chesterford Research Park, Little Chesterford, Essex CB10 1XL, United Kingdom
| | - A Rae
- Charles River Discovery Research Services, Chesterford Research Park, Little Chesterford, Essex CB10 1XL, United Kingdom.
| | - C Rouse
- Charles River Discovery Research Services, Chesterford Research Park, Little Chesterford, Essex CB10 1XL, United Kingdom
| | - G Wishart
- Charles River Discovery Research Services, Chesterford Research Park, Little Chesterford, Essex CB10 1XL, United Kingdom
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12
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Federico A, Lugoboni F, Mantovani E, Martini A, Morbioli L, Casari R, Faccini M, Tamburin S. Detoxification Improves Multidomain Cognitive Dysfunction in High-Dose Benzodiazepine Abusers. Front Neurosci 2020; 14:747. [PMID: 32848544 PMCID: PMC7396668 DOI: 10.3389/fnins.2020.00747] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Accepted: 06/25/2020] [Indexed: 02/03/2023] Open
Abstract
Purpose High-dose benzodiazepines (BZDs) abuse has been documented to cause multidomain cognitive dysfunction. We explored whether cognitive abnormalities to high-dose BZD abuse might be reversed by detoxification with slow subcutaneous infusion of flumazenil. Methods We recruited 96 patients consecutively admitted to the Department of Internal Medicine, Addiction Medicine Unit, Verona University Hospital, Italy for detoxification from high-dose BZD dependence. After selection for inclusion and exclusion criteria, 50 patients (23 men, 27 women; age 42.7 ± 10.3 years) were included. They underwent a comprehensive neuropsychological battery to explore verbal memory, visuospatial memory, working memory, attention, and executive functions 28–30 days prior to admission for detoxification (T0) and at the end of detoxification, i.e., 7 days after admission (T1). A group of 50 healthy adults (24 men, 26 women; mean age 44.5 ± 12.8 years) matched for age, sex, and education served as controls. Results At T0, patients scored significantly worse than healthy controls in all the neuropsychological tests. Depression and anxiety scores were associated with impaired verbal memory at T0 in patients. T1–T0 comparison showed improved performances in all neuropsychological tests after the end of detoxification in patients. Conclusion We confirmed that all neuropsychological domains were significantly and profoundly impaired by high-dose BZD abuse and documented that cognitive abnormalities improved after detoxification with slow subcutaneous infusion of flumazenil.
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Affiliation(s)
- Angela Federico
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Fabio Lugoboni
- Department of Medicine, Addiction Medicine Unit, Verona University Hospital, Verona, Italy
| | - Elisa Mantovani
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Alice Martini
- School of Psychology, Keele University, Newcastle-under-Lyme, United Kingdom
| | - Laura Morbioli
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy.,Department of Medicine, Addiction Medicine Unit, Verona University Hospital, Verona, Italy
| | - Rebecca Casari
- Department of Medicine, Addiction Medicine Unit, Verona University Hospital, Verona, Italy
| | - Marco Faccini
- Department of Medicine, Addiction Medicine Unit, Verona University Hospital, Verona, Italy
| | - Stefano Tamburin
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
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13
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Bi D, Wen L, Wu Z, Shen Y. GABAergic dysfunction in excitatory and inhibitory (E/I) imbalance drives the pathogenesis of Alzheimer's disease. Alzheimers Dement 2020; 16:1312-1329. [PMID: 32543726 DOI: 10.1002/alz.12088] [Citation(s) in RCA: 91] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 01/28/2020] [Accepted: 02/10/2020] [Indexed: 12/28/2022]
Abstract
OBJECTIVE To propose a new hypothesis that GABAergic dysfunction in excitatory and inhibitory (E/I) imbalance drives the pathogenesis of Alzheimer's disease (AD). BACKGROUND Synaptic dysfunction and E/I imbalance emerge decades before the appearance of cognitive decline in AD patients, which contribute to neurodegeneration. Initially, E/I imbalance was thought to occur first, due to dysfunction of the glutamatergic and cholinergic systems. However, new evidence has demonstrated that the GABAergic system, the counterpart of E/I balance and the major inhibitory neurotransmitter system in the central nervous system, is altered enormously and that this contributes to E/I imbalance and further AD pathogenesis. NEW HYPOTHESIS Alterations to the GABAergic system, induced by multiple AD pathogenic or risk factors, contribute to E/I imbalance and AD pathogenesis. MAJOR CHALLENGES FOR THE HYPOTHESIS This GABAergic hypothesis accounts for many critical questions and common challenges confronting a new hypothesis of AD pathogenesis. More specifically, it explains why amyloid beta (Aβ), β-secretase (BACE1), apolipoprotein E4 gene (APOE ε4), hyperactive glia cells, contributes to AD pathogenesis and why age and sex are the risk factors of AD. GABAergic dysfunction promotes the spread of Aβ pathology throughout the AD brain and associated cognitive impairments, and the induction of dysfunction induced by these varied risk factors shares this common neurobiology leading to E/I imbalance. In turn, some of these factors exacerbate GABAergic dysfunction and E/I imbalance. Moreover, the GABAergic system modulates various brain functions and thus, the GABAergic hypothesis accounts for nonamnestic manifestations. Furthermore, corrections of E/I balance through manipulation of GABAergic functions have shown positive outcomes in preclinical and clinical studies, suggesting the potential of the GABAergic system as a therapeutic target in AD. LINKAGE TO OTHER MAJOR THEORIES Dysfunction of the GABAergic system is induced by multiple critical signaling pathways, which include the existing major theories of AD pathogenesis, such as the Aβ and neuroinflammation hypotheses. In a new perspective, this GABAergic hypothesis accounts for the E/I imbalance and related excitotoxicity, which contribute to cognitive decline and AD pathogenesis. Therefore, the GABAergic system could be a key target to restore, at least partially, the E/I balance and cognitive function in AD patients.
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Affiliation(s)
- Danlei Bi
- The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Institute on Aging and Brain Disorders, University of Sciences and Technology of China, Hefei, China.,Neurodegenerative Disease Research Center, University of Science and Technology of China, Hefei, China.,Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Lang Wen
- The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Institute on Aging and Brain Disorders, University of Sciences and Technology of China, Hefei, China.,Neurodegenerative Disease Research Center, University of Science and Technology of China, Hefei, China.,Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Zujun Wu
- The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Institute on Aging and Brain Disorders, University of Sciences and Technology of China, Hefei, China.,Neurodegenerative Disease Research Center, University of Science and Technology of China, Hefei, China.,Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Yong Shen
- The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Institute on Aging and Brain Disorders, University of Sciences and Technology of China, Hefei, China.,Neurodegenerative Disease Research Center, University of Science and Technology of China, Hefei, China.,Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
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14
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Koh MT, Branch A, Haberman R, Gallagher M. Significance of inhibitory recruitment in aging with preserved cognition: limiting gamma-aminobutyric acid type A α5 function produces memory impairment. Neurobiol Aging 2020; 91:1-4. [PMID: 32240868 DOI: 10.1016/j.neurobiolaging.2020.02.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 12/30/2019] [Accepted: 02/22/2020] [Indexed: 01/27/2023]
Abstract
Numerous aging studies have identified a shift in the excitatory/inhibitory (E/I) balance with heightened hippocampal neural activity associated with age-related memory impairment across species, including rats, monkeys, and humans. Neurobiological investigations directed at the hippocampal formation have demonstrated that unimpaired aged rats performing on par with young adult rats in a spatial memory task exhibit gene expression profiles, mechanisms for plasticity, and altered circuit/network function, which are distinct from younger rats. Particularly striking is a convergence of observational evidence that aged unimpaired rats augment recruitment of mechanisms associated with neural inhibition, a finding that may represent an adaptive homeostatic adjustment necessary to maintain neural plasticity and memory function in aging. In this study, we test the effect of limiting inhibition via administration of TB21007, a negative allosteric modulator of the alpha 5 subtype of gamma-aminobutyric acid type A α5 receptor, on a radial arm maze assessment of memory function. Impaired memory performance produced by this intervention in otherwise high-performing aged rats supports an adaptive role for gamma-aminobutyric acid in the functional maintenance of intact cognition in aging.
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Affiliation(s)
- Ming Teng Koh
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Audrey Branch
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Rebecca Haberman
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA.
| | - Michela Gallagher
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
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15
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Duchon A, Gruart A, Albac C, Delatour B, Zorrilla de San Martin J, Delgado-García JM, Hérault Y, Potier MC. Long-lasting correction of in vivo LTP and cognitive deficits of mice modelling Down syndrome with an α5-selective GABA A inverse agonist. Br J Pharmacol 2020; 177:1106-1118. [PMID: 31652355 PMCID: PMC7042104 DOI: 10.1111/bph.14903] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 09/12/2019] [Accepted: 09/15/2019] [Indexed: 12/19/2022] Open
Abstract
Background and Purpose Excessive GABAergic inhibition contributes to cognitive dysfunctions in Down syndrome (DS). Selective negative allosteric modulators (NAMs) of α5‐containing GABAA receptors such as the α5 inverse agonist (α5IA) restore learning and memory deficits in Ts65Dn mice, a model of DS. In this study we have assessed the long‐lasting effects of α5IA on in vivo LTP and behaviour in Ts65Dn mice. Experimental Approach We made in vivo LTP recordings for six consecutive days in freely moving Ts65Dn mice and their wild‐type littermates, treated with vehicle or α5IA. In parallel, Ts65Dn mice were assessed by various learning and memory tests (Y maze, Morris water maze, or the novel object recognition) for up to 7 days, following one single injection of α5IA or vehicle. Key Results LTP was not evoked in vivo in Ts65Dn mice at hippocampal CA3‐CA1 synapses. However, this deficit was sustainably reversed for at least six consecutive days following a single injection of α5IA. This long‐lasting effect of α5IA was also observed when assessing working and long‐term memory deficits in Ts65Dn mice. Conclusion and Implications We show for the first time in vivo LTP deficits in Ts65Dn mice. These deficits were restored for at least 6 days following acute treatment with α5IA and might be the substrate for the long‐lasting pharmacological effects of α5IA on spatial working and long‐term recognition and spatial memory tasks. Our results demonstrate the relevance of negative allosteric modulators of α5‐containing GABAA receptors to the treatment of cognitive deficits associated with DS.
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Affiliation(s)
- Arnaud Duchon
- Translational Medicine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U1258, Illkirch, France.,Neuropôle, Université de Strasbourg, Illkirch, France
| | - Agnès Gruart
- División de Neurociencias, Universidad Pablo de Olavide, Seville, Spain
| | - Christelle Albac
- Institut du Cerveau et de la Moelle épinière, Hôpital de la Pitié-Salpêtrière, Paris, France.,Institut National de la Santé et de la Recherche Médicale, U1127, Hôpital de la Pitié-Salpêtrière, Paris, France.,Centre National de la Recherche Scientifique, UMR7225, Hôpital de la Pitié-Salpêtrière, Paris, France.,Sorbonne Université, Hôpital de la Pitié-Salpêtrière, Paris, France
| | - Benoît Delatour
- Institut du Cerveau et de la Moelle épinière, Hôpital de la Pitié-Salpêtrière, Paris, France.,Institut National de la Santé et de la Recherche Médicale, U1127, Hôpital de la Pitié-Salpêtrière, Paris, France.,Centre National de la Recherche Scientifique, UMR7225, Hôpital de la Pitié-Salpêtrière, Paris, France.,Sorbonne Université, Hôpital de la Pitié-Salpêtrière, Paris, France
| | - Javier Zorrilla de San Martin
- Institut du Cerveau et de la Moelle épinière, Hôpital de la Pitié-Salpêtrière, Paris, France.,Institut National de la Santé et de la Recherche Médicale, U1127, Hôpital de la Pitié-Salpêtrière, Paris, France.,Centre National de la Recherche Scientifique, UMR7225, Hôpital de la Pitié-Salpêtrière, Paris, France.,Sorbonne Université, Hôpital de la Pitié-Salpêtrière, Paris, France
| | | | - Yann Hérault
- Translational Medicine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U1258, Illkirch, France.,Neuropôle, Université de Strasbourg, Illkirch, France
| | - Marie-Claude Potier
- Institut du Cerveau et de la Moelle épinière, Hôpital de la Pitié-Salpêtrière, Paris, France.,Institut National de la Santé et de la Recherche Médicale, U1127, Hôpital de la Pitié-Salpêtrière, Paris, France.,Centre National de la Recherche Scientifique, UMR7225, Hôpital de la Pitié-Salpêtrière, Paris, France.,Sorbonne Université, Hôpital de la Pitié-Salpêtrière, Paris, France
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16
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Maramai S, Benchekroun M, Ward SE, Atack JR. Subtype Selective γ-Aminobutyric Acid Type A Receptor (GABAAR) Modulators Acting at the Benzodiazepine Binding Site: An Update. J Med Chem 2019; 63:3425-3446. [DOI: 10.1021/acs.jmedchem.9b01312] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Samuele Maramai
- Sussex Drug Discovery Centre, University of Sussex, Brighton BN1 9QJ, U.K
| | - Mohamed Benchekroun
- Sussex Drug Discovery Centre, University of Sussex, Brighton BN1 9QJ, U.K
- Équipe de Chimie Moléculaire, Laboratoire de Génomique Bioinformatique et Chimie Moléculaire, GBCM, EA7528, Conservatoire National des Arts et Métiers, 2 rue Conté, 75003 Paris, France
| | - Simon E. Ward
- Medicines Discovery Institute, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, U.K
| | - John R. Atack
- Medicines Discovery Institute, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, U.K
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17
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Gao T, Liu Y, Zhao Z, Luo Y, Wang L, Wang Y, Yin Y. L-655,708 Does not Prevent Isoflurane-induced Memory Deficits in Old Mice. Transl Neurosci 2019; 10:180-186. [PMID: 31410301 PMCID: PMC6689210 DOI: 10.1515/tnsci-2019-0032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 06/21/2019] [Indexed: 01/07/2023] Open
Abstract
Background General anesthesia and increasing age are two main risk factors for postoperative cognitive dysfunction (POCD). Effective agents for the prevention or treatment of POCD are urgently needed. L-655,708, an inverse agonist of α5 subunit-containing γ-aminobutyric acid subtype A (α5GABAA) receptors, can prevent anesthesia-induced memory deficits in young animals. However, there is a lack of evidence of its efficacy in old animals. Methodology Young (3- to 5-month-old) and old (18- to 20-month-old) mice were given an inhalation of 1.33% isoflurane for 1 hour and their associative memory was evaluated 24 hours after anesthesia using fear-conditioning tests (FCTs). To evaluate the effect of L-655,708, mice received intraperitoneal injections of L-655,708 (0.7 mg/kg) or vehicle 30 minutes before anesthesia. Results Old mice exhibited impaired memory and lower hippocampal α5GABAA levels than young mice under physiological conditions. Pre-injections of L-655,708 significantly alleviated isoflurane-induced memory decline in young mice, but not in old mice. Conclusions L-655,708 is not as effective for the prevention of POCD in old mice as it is in young mice. The use of inverse agonists of α5GABAA in preventing POCD in old patients should be carefully considered.
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Affiliation(s)
- Teng Gao
- Department of Anesthesiology, Beijing Shijitan Hospital, Capital Medical University, Beijing, 100038, China
| | - Yue Liu
- Department of Anesthesiology, China-Japan Friendship Hospital, Beijing, 100029, China
| | - Zifang Zhao
- Department of Anesthesiology, China-Japan Friendship Hospital, Beijing, 100029, China
| | - Yuan Luo
- State Key Laboratory of Toxicology and Medical Countermeasures, Academy of Military Medical Sciences, Beijing, 100850, China
| | - Lifang Wang
- Department of Anesthesiology, China-Japan Friendship Hospital, Beijing, 100029, China
| | - Yongan Wang
- State Key Laboratory of Toxicology and Medical Countermeasures, Academy of Military Medical Sciences, Beijing, 100850, China
| | - Yiqing Yin
- Department of Anesthesiology, China-Japan Friendship Hospital, Beijing, 100029, China
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18
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Jacob TC. Neurobiology and Therapeutic Potential of α5-GABA Type A Receptors. Front Mol Neurosci 2019; 12:179. [PMID: 31396049 PMCID: PMC6668551 DOI: 10.3389/fnmol.2019.00179] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 07/08/2019] [Indexed: 01/11/2023] Open
Abstract
α5 subunit containing GABA type A receptors (GABAARs) have long been an enigmatic receptor subtype of interest due to their specific brain distribution, unusual surface localization and key role in synaptic plasticity, cognition and memory. These receptors are uniquely positioned to sculpt both the developing and mature hippocampal circuitry due to high overall expression and a distinct peak within the critical synapse formation period during the second postnatal week. Unlike the majority of other GABAARs, they exhibit both receptor clustering at extrasynaptic sites via interactions with the radixin scaffold as well as synaptic sites via gephyrin, thus contributing respectively to tonic currents and synaptic GABAergic neurotransmission. α5 GABAAR signaling can be altered in neurodevelopmental disorders including autism and mental retardation and by inflammation in CNS injury and disease. Due to the unique physiology and pharmacology of α5 GABAARs, drugs targeting these receptors are being developed and tested as treatments for neurodevelopmental disorders, depression, schizophrenia, and mild cognitive impairment. This review article focuses on advances in understanding how the α5 subunit contributes to GABAAR neurobiology. In particular, I discuss both recent insights and remaining knowledge gaps for the functional role of these receptors, pathologies associated with α5 GABAAR dysfunction, and the effects and potential therapeutic uses of α5 receptor subtype targeted drugs.
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Affiliation(s)
- Tija C Jacob
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
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19
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Shi Y, Fang YY, Wei YP, Jiang Q, Zeng P, Tang N, Lu Y, Tian Q. Melatonin in Synaptic Impairments of Alzheimer's Disease. J Alzheimers Dis 2019; 63:911-926. [PMID: 29710712 DOI: 10.3233/jad-171178] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Alzheimer's disease (AD) underlies dementia for millions of people worldwide with no effective treatment. The dementia of AD is thought stem from the impairments of the synapses because of their critical roles in cognition. Melatonin is a neurohormone mainly released by the pineal gland in a circadian manner and it regulates brain functions in various manners. It is reported that both the melatonin deficit and synaptic impairments are present in the very early stage of AD and strongly contribute to the progress of AD. In the mammalian brains, the effects of melatonin are mainly relayed by two of its receptors, melatonin receptor type 1a (MT1) and 1b (MT2). To have a clear idea on the roles of melatonin in synaptic impairments of AD, this review discussed the actions of melatonin and its receptors in the stabilization of synapses, modulation of long-term potentiation, as well as their contributions in the transmissions of glutamatergic, GABAergic and dopaminergic synapses, which are the three main types of synapses relevant to the synaptic strength. The synaptic protective roles of melatonin in AD treatment were also summarized. Regarding its protective roles against amyloid-β neurotoxicity, tau hyperphosphorylation, oxygenation, inflammation as well as synaptic dysfunctions, melatonin may be an ideal therapeutic agent against AD at early stage.
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Affiliation(s)
- Yan Shi
- Department of Pathology and Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Key Laboratory of Neurological Disease of National Education Ministry and Hubei Province, Institute for Brain Research, Huazhong University of Science and Technology, Wuhan, China
| | - Ying-Yan Fang
- Department of Pathology and Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Key Laboratory of Neurological Disease of National Education Ministry and Hubei Province, Institute for Brain Research, Huazhong University of Science and Technology, Wuhan, China
| | - Yu-Ping Wei
- Department of Pathology and Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Key Laboratory of Neurological Disease of National Education Ministry and Hubei Province, Institute for Brain Research, Huazhong University of Science and Technology, Wuhan, China
| | - Qian Jiang
- Integrated TCM and Western Medicine Hospital, Huazhong University of Science and Technology, Wuhan, China
| | - Peng Zeng
- Department of Pathology and Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Key Laboratory of Neurological Disease of National Education Ministry and Hubei Province, Institute for Brain Research, Huazhong University of Science and Technology, Wuhan, China
| | - Na Tang
- Department of Pathology and Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Key Laboratory of Neurological Disease of National Education Ministry and Hubei Province, Institute for Brain Research, Huazhong University of Science and Technology, Wuhan, China
| | - Youming Lu
- Department of Pathology and Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Key Laboratory of Neurological Disease of National Education Ministry and Hubei Province, Institute for Brain Research, Huazhong University of Science and Technology, Wuhan, China
| | - Qing Tian
- Department of Pathology and Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Key Laboratory of Neurological Disease of National Education Ministry and Hubei Province, Institute for Brain Research, Huazhong University of Science and Technology, Wuhan, China
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20
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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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21
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Enhanced Dendritic Inhibition and Impaired NMDAR Activation in a Mouse Model of Down Syndrome. J Neurosci 2019; 39:5210-5221. [PMID: 31000585 DOI: 10.1523/jneurosci.2723-18.2019] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 04/09/2019] [Accepted: 04/10/2019] [Indexed: 11/21/2022] Open
Abstract
Down syndrome (DS) or Trisomy 21 is a developmental disorder leading to cognitive deficits, including disruption of hippocampus-dependent learning and memory. Enhanced inhibition has been suggested to underlie these deficits in DS based on studies using the Ts65Dn mouse model. Here we show that, in this mouse model, GABAergic synaptic inhibition onto dendrites of hippocampal pyramidal cells is increased. By contrast, somatic inhibition was not altered. In addition, synaptic NMDAR currents were reduced. Furthermore, dendritic inhibition was mediated via nonlinear α5-subunit containing GABAARs that closely matched the kinetics and voltage dependence of NMDARs. Thus, enhanced dendritic inhibition and reduced NMDA currents strongly decreased burst-induced NMDAR-mediated depolarization and impaired LTP induction. Finally, selective reduction of α5-GABAAR-mediated inhibition rescued both burst-induced synaptic NMDAR activation and synaptic plasticity. These results demonstrate that reduced synaptic NMDAR activation and synaptic plasticity in the Ts65Dn mouse model of DS can be corrected by specifically targeting nonlinear dendritic inhibition.SIGNIFICANCE STATEMENT Mild to moderate intellectual disability is a prominent feature of Down syndrome. Previous studies in mouse models suggest that increased synaptic inhibition is a main factor for decreased synaptic plasticity, the cellular phenomenon underlying memory. The present study shows that increased inhibition specifically onto dendrites together with reduced NMDAR content in excitatory synapses may be the cause. Reducing a slow nonlinear component that is specific to dendritic inhibitory inputs and mediated by α5 subunit-containing GABAA receptors rescues both NMDAR activation and synaptic plasticity.
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Branch A, Monasterio A, Blair G, Knierim JJ, Gallagher M, Haberman RP. Aged rats with preserved memory dynamically recruit hippocampal inhibition in a local/global cue mismatch environment. Neurobiol Aging 2019; 76:151-161. [PMID: 30716540 DOI: 10.1016/j.neurobiolaging.2018.12.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 12/14/2018] [Accepted: 12/27/2018] [Indexed: 10/27/2022]
Abstract
Similar to elderly humans, aged outbred Long-Evans rats exhibit individual differences in memory abilities, including a subset of aged rats that maintain memory function on par with young adults. Such individuals provide a basis for investigating mechanisms of resilience to age-related decline. The present study examined hippocampal gene expression in young adults and aged rats with preserved memory function under behavioral task conditions well established for assessing information processing central to the formation of episodic memory. Although behavioral measures and hippocampal gene induction associated with neural activity and synaptic plasticity were similar across age groups, a marker for inhibitory interneuron function in the hippocampal formation was distinctively increased only in aged rats but not in young adults. Because heightened hippocampal neural activity is associated with age-related memory impairment across species, including rats, monkeys, and humans, this finding may represent an adaptive homeostatic adjustment necessary to maintain neural plasticity and memory function in aging.
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Affiliation(s)
- Audrey Branch
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Amy Monasterio
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Grace Blair
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - James J Knierim
- Department of Neuroscience and Zanvyl Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Michela Gallagher
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Rebecca P Haberman
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA.
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23
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Mohamad FH, Has ATC. The α5-Containing GABA A Receptors-a Brief Summary. J Mol Neurosci 2019; 67:343-351. [PMID: 30607899 DOI: 10.1007/s12031-018-1246-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Accepted: 12/17/2018] [Indexed: 12/21/2022]
Abstract
GABAA receptors are the major inhibitory neurotransmitter receptor in the human brain. The receptors are assembled from combination of protein subunits in pentameric complex which may consist of α1-6, β1-3, γ1-3, ρ1-3, δ, ε, θ, or π subunits. There are a theoretical > 150,000 possible assemblies and arrangements of GABAA subunits, although only a few combinations have been found in human with the most dominant consists of 2α1, 2β2, and 1γ2 in a counterclockwise arrangement as seen from the synaptic cleft. The receptors also possess binding sites for various unrelated substances including benzodiazepines, barbiturates, and anesthetics. The α5-containing GABAARs only make up ≤ 5% of the entire receptor population, but up to 25% of the receptor subtype is located in the crucial learning and memory-associated area of the brain-the hippocampus, which has ignited myriads of hypotheses and theories in regard to its role. As well as exhibiting synaptic phasic inhibition, the α5-containing receptors are also extrasynaptic and mediate tonic inhibition with continuously occurring smaller amplitude. Studies on negative-allosteric modulators for reducing this tonic inhibition have been shown to enhance learning and memory in neurological disorders such as schizophrenia, Down syndrome, and autism with a possible alternative benzodiazepine binding site. Therefore, a few α5 subunit-specific compounds have been developed to address these pharmacological needs. With its small population, the α5-containing receptors could be the key and also the answer for many untreated cognitive dysfunctions and disorders.
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Affiliation(s)
- Fatin H Mohamad
- Department of Neurosciences, School of Medical Sciences, Universiti Sains Malaysia, Kampus Kesihatan, 16150, Kubang Kerian, Kelantan, Malaysia
| | - Ahmad Tarmizi Che Has
- Department of Neurosciences, School of Medical Sciences, Universiti Sains Malaysia, Kampus Kesihatan, 16150, Kubang Kerian, Kelantan, Malaysia.
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Golovko AI, Ivanov MB, Golovko ES, Dolgo-Saburov VB, Zatsepin EP. The Neurochemical Mechanisms of the Pharmacological Activities of Inverse Agonists of the Benzodiazepine Binding Site. NEUROCHEM J+ 2018. [DOI: 10.1134/s1819712418030042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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25
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Sieghart W, Savić MM. International Union of Basic and Clinical Pharmacology. CVI: GABAA Receptor Subtype- and Function-selective Ligands: Key Issues in Translation to Humans. Pharmacol Rev 2018; 70:836-878. [DOI: 10.1124/pr.117.014449] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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26
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Szodorai E, Bampali K, Romanov RA, Kasper S, Hökfelt T, Ernst M, Lubec G, Harkany T. Diversity matters: combinatorial information coding by GABA A receptor subunits during spatial learning and its allosteric modulation. Cell Signal 2018; 50:142-159. [DOI: 10.1016/j.cellsig.2018.07.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 07/08/2018] [Accepted: 07/09/2018] [Indexed: 01/11/2023]
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27
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Dendrite-targeting interneurons control synaptic NMDA-receptor activation via nonlinear α5-GABA A receptors. Nat Commun 2018; 9:3576. [PMID: 30177704 PMCID: PMC6120902 DOI: 10.1038/s41467-018-06004-8] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 08/03/2018] [Indexed: 12/18/2022] Open
Abstract
Dendrite-targeting GABAergic interneurons powerfully control postsynaptic integration, synaptic plasticity, and learning. However, the mechanisms underlying the efficient GABAergic control of dendritic electrogenesis are not well understood. Using subtype-selective blockers for GABAA receptors, we show that dendrite-targeting somatostatin interneurons and NO-synthase-positive neurogliaform cells preferentially activate α5-subunit- containing GABAA receptors (α5-GABAARs), generating slow inhibitory postsynaptic currents (IPSCs) in hippocampal CA1 pyramidal cells. By contrast, only negligible contribution of these receptors could be found in perisomatic IPSCs, generated by fast-spiking parvalbumin interneurons. Remarkably, α5-GABAAR-mediated IPSCs were strongly outward-rectifying generating 4-fold larger conductances above –50 mV than at rest. Experiments and modeling show that synaptic activation of these receptors can very effectively control voltage-dependent NMDA-receptor activation as well as Schaffer-collateral evoked burst firing in pyramidal cells. Taken together, nonlinear-rectifying α5-GABAARs with slow kinetics match functional NMDA-receptor properties and thereby mediate powerful control of dendritic postsynaptic integration and action potential firing by dendrite-targeting interneurons. Somatostatin+ (SOM+ ) GABAergic interneurons are known to fine-tune synaptic plasticity as they inhibit dendritic spikes and burst firing. Here, the authors show that both SOM+ and NOS+ interneurons preferentially recruit nonlinear outward-rectifying GABA(A)R with alpha5 subunit, and that this inhibition with slow gating kinetics matches voltage and time-dependent activation of synaptic NMDARs, thereby controlling the generation of dendritic NMDA spikes.
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28
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Knoflach F, Hernandez MC, Bertrand D. Methods for the Discovery of Novel Compounds Modulating a Gamma-Aminobutyric Acid Receptor Type A Neurotransmission. J Vis Exp 2018. [PMID: 30175997 PMCID: PMC6128072 DOI: 10.3791/57842] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
This manuscript presents a step-by-step protocol for screening compounds at gamma-aminobutyric acid type A (GABAA) receptors and its use towards the identification of novel molecules active in preclinical assays from an in vitro recombinant receptor to their pharmacological effects at native receptors in rodent brain slices. For compounds binding at the benzodiazepine site of the receptor, the first step is to set up a primary screen that consists of developing radioligand binding assays on cell membranes expressing the major GABAA subtypes. Then, taking advantage of the heterologous expression of rodent and human GABAA receptors in Xenopus oocytes or HEK 293 cells, it is possible to explore, in electrophysiological assays, the physiological properties of the different receptor subtypes and the pharmacological properties of the identified compounds. The Xenopus oocyte system will be presented here, starting with the isolation of the oocytes and their microinjection with different mRNAs, up to the pharmacological characterization using two-electrode voltage clamps. Finally, recordings conducted in rodent brain slices will be described that are used as a secondary physiological test to assess the activity of molecules at their native receptors in a well-defined neuronal circuit. Extracellular recordings using population responses of multiple neurons are demonstrated together with the drug application.
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Affiliation(s)
- Frédéric Knoflach
- Discovery Neuroscience, Pharma Research and Early Development, Roche Innovation Center Basel
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29
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Ralvenius WT, Neumann E, Pagani M, Acuña MA, Wildner H, Benke D, Fischer N, Rostaher A, Schwager S, Detmar M, Frauenknecht K, Aguzzi A, Hubbs JL, Rudolph U, Favrot C, Zeilhofer HU. Itch suppression in mice and dogs by modulation of spinal α2 and α3GABA A receptors. Nat Commun 2018; 9:3230. [PMID: 30104684 PMCID: PMC6089996 DOI: 10.1038/s41467-018-05709-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 07/20/2018] [Indexed: 11/10/2022] Open
Abstract
Chronic itch is a highly debilitating condition affecting about 10% of the general population. The relay of itch signals is under tight control by inhibitory circuits of the spinal dorsal horn, which may offer a hitherto unexploited therapeutic opportunity. Here, we found that specific pharmacological targeting of inhibitory α2 and α3GABAA receptors reduces acute histaminergic and non-histaminergic itch in mice. Systemic treatment with an α2/α3GABAA receptor selective modulator alleviates also chronic itch in a mouse model of atopic dermatitis and in dogs sensitized to house dust mites, without inducing sedation, motor dysfunction, or loss of antipruritic activity after prolonged treatment. Transsynaptic circuit tracing, immunofluorescence, and electrophysiological experiments identify spinal α2 and α3GABAA receptors as likely molecular targets underlying the antipruritic effect. Our results indicate that drugs targeting α2 and α3GABAA receptors are well-suited to alleviate itch, including non-histaminergic chronic itch for which currently no approved treatment exists.
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Affiliation(s)
- William T Ralvenius
- Institute of Pharmacology and Toxicology, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - Elena Neumann
- Institute of Pharmacology and Toxicology, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - Martina Pagani
- Institute of Pharmacology and Toxicology, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland.,Neuroscience Center Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - Mario A Acuña
- Institute of Pharmacology and Toxicology, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - Hendrik Wildner
- Institute of Pharmacology and Toxicology, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - Dietmar Benke
- Institute of Pharmacology and Toxicology, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland.,Neuroscience Center Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland.,Drug Discovery Network Zürich (DDNZ), Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - Nina Fischer
- Dermatology Department, Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, Winterthurerstrasse 260, CH-8057, Zürich, Switzerland
| | - Ana Rostaher
- Dermatology Department, Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, Winterthurerstrasse 260, CH-8057, Zürich, Switzerland
| | - Simon Schwager
- Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zürich, Vladimir-Prelog-Weg 1-5/10, CH-8093, Zürich, Switzerland
| | - Michael Detmar
- Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zürich, Vladimir-Prelog-Weg 1-5/10, CH-8093, Zürich, Switzerland
| | - Katrin Frauenknecht
- Institute of Neuropathology, University of Zürich and University Hospital Zürich, Schmelzbergstrasse 12, CH-8091, Zürich, Switzerland
| | - Adriano Aguzzi
- Institute of Neuropathology, University of Zürich and University Hospital Zürich, Schmelzbergstrasse 12, CH-8091, Zürich, Switzerland
| | - Jed Lee Hubbs
- Laboratory of Organic Chemistry, Swiss Federal Institute of Technology (ETH) Zürich, Vladimir-Prelog-Weg 1-5/10, CH-8093, Zürich, Switzerland
| | - Uwe Rudolph
- Laboratory of Genetic Neuropharmacology, McLean Hospital, 115 Mill Street, Belmont, MA, 02478, USA.,Department of Psychiatry, Harvard Medical School, 401 Park Drive, Boston, MA, 02215, USA
| | - Claude Favrot
- Dermatology Department, Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, Winterthurerstrasse 260, CH-8057, Zürich, Switzerland
| | - Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland. .,Neuroscience Center Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland. .,Drug Discovery Network Zürich (DDNZ), Winterthurerstrasse 190, CH-8057, Zürich, Switzerland. .,Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zürich, Vladimir-Prelog-Weg 1-5/10, CH-8093, Zürich, Switzerland.
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30
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Calvo-Flores Guzmán B, Vinnakota C, Govindpani K, Waldvogel HJ, Faull RL, Kwakowsky A. The GABAergic system as a therapeutic target for Alzheimer's disease. J Neurochem 2018; 146:649-669. [DOI: 10.1111/jnc.14345] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 02/21/2018] [Accepted: 03/14/2018] [Indexed: 12/14/2022]
Affiliation(s)
- Beatriz Calvo-Flores Guzmán
- Centre for Brain Research; Faculty of Medical and Health Sciences; Department of Anatomy and Medical Imaging; University of Auckland; Auckland New Zealand
| | - Chitra Vinnakota
- Centre for Brain Research; Faculty of Medical and Health Sciences; Department of Anatomy and Medical Imaging; University of Auckland; Auckland New Zealand
| | - Karan Govindpani
- Centre for Brain Research; Faculty of Medical and Health Sciences; Department of Anatomy and Medical Imaging; University of Auckland; Auckland New Zealand
| | - Henry J. Waldvogel
- Centre for Brain Research; Faculty of Medical and Health Sciences; Department of Anatomy and Medical Imaging; University of Auckland; Auckland New Zealand
| | - Richard L.M. Faull
- Centre for Brain Research; Faculty of Medical and Health Sciences; Department of Anatomy and Medical Imaging; University of Auckland; Auckland New Zealand
| | - Andrea Kwakowsky
- Centre for Brain Research; Faculty of Medical and Health Sciences; Department of Anatomy and Medical Imaging; University of Auckland; Auckland New Zealand
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31
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Quercetin Reduces Cortical GABAergic Transmission and Alleviates MK-801-Induced Hyperactivity. EBioMedicine 2018; 34:201-213. [PMID: 30057312 PMCID: PMC6116474 DOI: 10.1016/j.ebiom.2018.07.031] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Revised: 07/11/2018] [Accepted: 07/20/2018] [Indexed: 02/06/2023] Open
Abstract
An imbalance between neuronal excitation and inhibition represents a core feature in multiple neuropsychiatry disorders, necessitating the development of novel strategies to calibrate the excitatory–inhibitory balance of therapeutics. Here we identify a natural compound quercetin that reduces prefrontal cortical GABAergic transmission and alleviates the hyperactivity induced by glutamatergic N-methyl-d-aspartate receptor antagonist MK-801. Quercetin markedly reduced the GABA-activated currents in a noncompetitive manner in cultured cortical neurons, and moderately inhibited spontaneous and electrically-evoked GABAergic inhibitory postsynaptic current in mouse prefrontal cortical slices. Notably, systemic and prefrontal-specific delivery of quercetin reduced basal locomotor activity in addition to alleviated the MK-801-induced hyperactivity. The effects of quercetin were not exclusively dependent on α5-subunit-containing A type GABA receptors (GABAARs), as viral-mediated, region-specific genetic knockdown of the α5-subunit in prefrontal cortex improved the MK-801-evoked psychotic symptom but reserved the pharmacological responsivity to quercetin. Both interventions together completely normalized the locomotor activity. Together, quercetin as a negative allosteric GABAAR modulator exerted antipsychotic activity, facilitating further therapeutic development for the excitatory–inhibitory imbalance disorders.
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32
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The Benzodiazepine Binding Sites of GABAA Receptors. Trends Pharmacol Sci 2018; 39:659-671. [DOI: 10.1016/j.tips.2018.03.006] [Citation(s) in RCA: 107] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 03/15/2018] [Accepted: 03/22/2018] [Indexed: 11/24/2022]
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33
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Xu MY, Wong AHC. GABAergic inhibitory neurons as therapeutic targets for cognitive impairment in schizophrenia. Acta Pharmacol Sin 2018; 39:733-753. [PMID: 29565038 DOI: 10.1038/aps.2017.172] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 12/25/2017] [Indexed: 12/24/2022] Open
Abstract
Schizophrenia is considered primarily as a cognitive disorder. However, functional outcomes in schizophrenia are limited by the lack of effective pharmacological and psychosocial interventions for cognitive impairment. GABA (gamma-aminobutyric acid) interneurons are the main inhibitory neurons in the central nervous system (CNS), and they play a critical role in a variety of pathophysiological processes including modulation of cortical and hippocampal neural circuitry and activity, cognitive function-related neural oscillations (eg, gamma oscillations) and information integration and processing. Dysfunctional GABA interneuron activity can disrupt the excitatory/inhibitory (E/I) balance in the cortex, which could represent a core pathophysiological mechanism underlying cognitive dysfunction in schizophrenia. Recent research suggests that selective modulation of the GABAergic system is a promising intervention for the treatment of schizophrenia-associated cognitive defects. In this review, we summarized evidence from postmortem and animal studies for abnormal GABAergic neurotransmission in schizophrenia, and how altered GABA interneurons could disrupt neuronal oscillations. Next, we systemically reviewed a variety of up-to-date subtype-selective agonists, antagonists, positive and negative allosteric modulators (including dual allosteric modulators) for α5/α3/α2 GABAA and GABAB receptors, and summarized their pro-cognitive effects in animal behavioral tests and clinical trials. Finally, we also discuss various representative histone deacetylases (HDAC) inhibitors that target GABA system through epigenetic modulations, GABA prodrug and presynaptic GABA transporter inhibitors. This review provides important information on current potential GABA-associated therapies and future insights for development of more effective treatments.
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34
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Kawaharada S, Nakanishi M, Nakanishi N, Hazama K, Higashino M, Yasuhiro T, Lewis A, Clark GS, Chambers MS, Maidment SA, Katsumata S, Kaneko S. ONO-8590580, a Novel GABAAα5 Negative Allosteric Modulator Enhances Long-Term Potentiation and Improves Cognitive Deficits in Preclinical Models. J Pharmacol Exp Ther 2018; 366:58-65. [DOI: 10.1124/jpet.117.247627] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 04/17/2018] [Indexed: 01/10/2023] Open
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35
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Xu NZ, Ernst M, Treven M, Cerne R, Wakulchik M, Li X, Jones TM, Gleason SD, Morrow D, Schkeryantz JM, Rahman MT, Li G, Poe MM, Cook JM, Witkin JM. Negative allosteric modulation of alpha 5-containing GABA A receptors engenders antidepressant-like effects and selectively prevents age-associated hyperactivity in tau-depositing mice. Psychopharmacology (Berl) 2018; 235:1151-1161. [PMID: 29374303 DOI: 10.1007/s00213-018-4832-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 01/07/2018] [Indexed: 02/08/2023]
Abstract
RATIONALE Associated with frank neuropathology, patients with Alzheimer's disease suffer from a host of neuropsychiatric symptoms that include depression, apathy, agitation, and aggression. Negative allosteric modulators (NAMs) of α5-containing GABAA receptors have been suggested to be a novel target for antidepressant action. We hypothesized that pharmacological modulation of this target would engender increased motivation in stressful environments. METHODS We utilized electrophysiological recordings from Xenopus oocytes and behavioral measures in mice to address this hypothesis. RESULTS In the forced-swim assay in mice that detects antidepressant drugs, the α5β3γ2 GABAΑ receptor NAM, RY-080 produced a marked antidepressant phenotype. Another compound, PWZ-029, was characterized as an α5β3γ2 receptor NAM of lower intrinsic efficacy in electrophysiological studies in Xenopus oocytes. In contrast to RY-080, PWZ-029 was only moderately active in the forced-swim assay and the α5β3γ2 receptor antagonist, Xli-093, was not active at all. The effects of RY-080 were prevented by the non-selective benzodiazepine receptor antagonist flumazenil as well as by the selective ligands, PWZ-029 and Xli-093. These findings demonstrate that this effect of RY-080 is driven by negative allosteric modulation of α5βγ2 GABAA receptors. RY-080 was not active in the tail-suspension test. We also demonstrated a reduction in the age-dependent hyperactivity exhibited by transgenic mice that accumulate pathological tau (rTg4510 mice) by RY-080. The decrease in hyperactivity by RY-080 was selective for the hyperactivity of the rTg4510 mice since the locomotion of control strains of mice were not significantly affected by RY-080. CONCLUSIONS α5βγ2 GABAA receptor NAMs might function as a pharmacological treatment for mood, amotivational syndromes, and psychomotor agitation in patients with Alzheimer's and other neurodegenerative disorders.
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Affiliation(s)
- Nina Z Xu
- The Lilly Research Labs, Eli Lilly and Company, Indianapolis, IN, USA
| | - Margot Ernst
- Department of Molecular Neurosciences Center for Brain Research, Medical University of Vienna, Spitalgasse 4, Vienna, Austria
| | - Marco Treven
- Department of Molecular Neurosciences Center for Brain Research, Medical University of Vienna, Spitalgasse 4, Vienna, Austria
| | - Rok Cerne
- The Lilly Research Labs, Eli Lilly and Company, Indianapolis, IN, USA
| | - Mark Wakulchik
- The Lilly Research Labs, Eli Lilly and Company, Indianapolis, IN, USA
| | - Xia Li
- The Lilly Research Labs, Eli Lilly and Company, Indianapolis, IN, USA
| | - Timothy M Jones
- The Lilly Research Labs, Eli Lilly and Company, Indianapolis, IN, USA
| | - Scott D Gleason
- The Lilly Research Labs, Eli Lilly and Company, Indianapolis, IN, USA
| | - Denise Morrow
- The Lilly Research Labs, Eli Lilly and Company, Indianapolis, IN, USA
| | | | - Md Toufiqur Rahman
- Department of Chemistry and Biochemistry, University of Wisconsin Milwaukee, Milwaukee, WI, USA
| | - Guanguan Li
- Department of Chemistry and Biochemistry, University of Wisconsin Milwaukee, Milwaukee, WI, USA
| | - Michael M Poe
- Department of Chemistry and Biochemistry, University of Wisconsin Milwaukee, Milwaukee, WI, USA
| | - James M Cook
- Department of Chemistry and Biochemistry, University of Wisconsin Milwaukee, Milwaukee, WI, USA
| | - Jeffrey M Witkin
- The Lilly Research Labs, Eli Lilly and Company, Indianapolis, IN, USA.
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36
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Block A, Ahmed M, Rueda N, Hernandez MC, Martinez-Cué C, Gardiner K. The GABA A α5-selective Modulator, RO4938581, Rescues Protein Anomalies in the Ts65Dn Mouse Model of Down Syndrome. Neuroscience 2018; 372:192-212. [DOI: 10.1016/j.neuroscience.2017.12.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 12/19/2017] [Accepted: 12/21/2017] [Indexed: 12/21/2022]
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37
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Zorrilla de San Martin J, Delabar JM, Bacci A, Potier MC. GABAergic over-inhibition, a promising hypothesis for cognitive deficits in Down syndrome. Free Radic Biol Med 2018; 114:33-39. [PMID: 28993272 DOI: 10.1016/j.freeradbiomed.2017.10.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 10/01/2017] [Accepted: 10/04/2017] [Indexed: 12/31/2022]
Abstract
Down syndrome (DS), also known as trisomy 21, is the most common genetic cause of intellectual disability. It is also a model human disease for exploring consequences of gene dosage imbalance on complex phenotypes. Learning and memory impairments linked to intellectual disabilities in DS could result from synaptic plasticity deficits and excitatory-inhibitory alterations leading to changes in neuronal circuitry in the brain of affected individuals. Increasing number of studies in mouse and cellular models converge towards the assumption that excitatory-inhibitory imbalance occurs in DS, likely early during development. Thus increased inhibition appears to be a common trend that could explain synaptic and circuit disorganization. Interestingly using several potent pharmacological tools, preclinical studies strongly demonstrated that cognitive deficits could be restored in mouse models of DS. Clinical trials have not yet provided robust data for therapeutic application and additional studies are needed. Here we review the literature and our own published work emphasizing the over-inhibition hypothesis in DS and their links with gene dosage imbalance paving the way for future basic and clinical research.
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Affiliation(s)
- Javier Zorrilla de San Martin
- INSERM U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMRS 1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | - Jean-Maurice Delabar
- INSERM U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMRS 1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | - Alberto Bacci
- INSERM U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMRS 1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | - Marie-Claude Potier
- INSERM U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMRS 1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France.
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Hippocampal GABA A antagonism reverses the novel object recognition deficit in sub-chronic phencyclidine-treated rats. Behav Brain Res 2017; 342:11-18. [PMID: 29289597 DOI: 10.1016/j.bbr.2017.12.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 12/20/2017] [Accepted: 12/26/2017] [Indexed: 12/14/2022]
Abstract
BACKGROUND Abnormalities in prefrontal cortical and hippocampal GABAergic function are postulated to be major causes of the cognitive impairment associated with schizophrenia (CIAS). There are conflicting views on whether diminished or enhanced GABAergic activity contributes to the deficit in short-term novel object recognition (NOR) in the sub-chronic phencyclidine (scPCP) rodent model of CIAS. This study assessed the role of GABAA signaling in the medial prefrontal cortex (mPFC) and ventral hippocampus (vHPC) in NOR in saline (scSAL)- and scPCP-treated rats. METHODS The effects of local administration of a GABAA agonist (muscimol) into the vHPC or mPFC and an antagonist (bicuculline) or a GABAA/benzodiazepine partial agonist (bretazenil) into the vHPC on NOR in scSAL and scPCP-treated rats were determined. RESULTS In scSAL-treated rats, injection of muscimol into the vHPC, but not mPFC, induced a deficit in NOR. The scPCP-induced NOR deficit was significantly reversed by intra-vHPC bicuculline, while intra-vHPC bretazenil produced a non-significant trend for reversal (p = .06). scPCP treatment increased mRNA expression of GABAA γ2 in PFC and GABAA α5 and GABAA β1 in the HPC. However, GABA concentration in the PFC or HPC was not altered. CONCLUSIONS These findings indicate that the scPCP-induced NOR deficit can be rescued by reducing GABAA receptor stimulation in vHPC, indicating that increased vHPC GABAA inhibition may contribute to the scPCP-induced NOR deficit in rats. These results also indicate that excessive GABAA receptor signalling in the vHPC has a deleterious effect on NOR in normal rats.
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Mar AC, Nilsson SRO, Gamallo-Lana B, Lei M, Dourado T, Alsiö J, Saksida LM, Bussey TJ, Robbins TW. MAM-E17 rat model impairments on a novel continuous performance task: effects of potential cognitive enhancing drugs. Psychopharmacology (Berl) 2017; 234:2837-2857. [PMID: 28744563 PMCID: PMC5591806 DOI: 10.1007/s00213-017-4679-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 06/18/2017] [Indexed: 12/02/2022]
Abstract
RATIONALE Impairments in attention and inhibitory control are endophenotypic markers of neuropsychiatric disorders such as schizophrenia and represent key targets for therapeutic management. Robust preclinical models and assays sensitive to clinically relevant treatments are crucial for improving cognitive enhancement strategies. OBJECTIVES We assessed a rodent model with neural and behavioral features relevant to schizophrenia (gestational day 17 methylazoxymethanol acetate treatment (MAM-E17)) on a novel test of attention and executive function, and examined the impact of putative nootropic drugs. METHODS MAM-E17 and sham control rats were trained on a novel touchscreen-based rodent continuous performance test (rCPT) designed to closely mimic the human CPT paradigm. Performance following acute, systemic treatment with an array of pharmacological compounds was investigated. RESULTS Two cohorts of MAM-E17 rats were impaired on rCPT performance including deficits in sensitivity (d') and increased false alarm rates (FARs). Sulpiride (0-30 mg/kg) dose-dependently reduced elevated FAR in MAM-E17 rats whereas low-dose modafinil (8 mg/kg) only improved d' in sham controls. ABT-594 (5.9-19.4 μg/kg) and modafinil (64 mg/kg) showed expected stimulant-like effects, while LSN2463359 (5 mg/kg), RO493858 (10 mg/kg), atomoxetine (0.3-1 mg/kg), and sulpiride (30 mg/kg) showed expected suppressant effects on performance across all animals. Donepezil (0.1-1 mg/kg) showed near-significant enhancements in d', and EVP-6124 (0.3-3 mg/kg) exerted no effects in the rCPT paradigm. CONCLUSION The MAM-E17 model exhibits robust and replicable impairments in rCPT performance that resemble attention and inhibitory control deficits seen in schizophrenia. Pharmacological profiles were highly consistent with known drug effects on cognition in preclinical and clinical studies. The rCPT is a sensitive and reliable tool with high translational potential for understanding the etiology and treatment of disorders affecting attention and executive dysfunction.
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Affiliation(s)
- Adam C Mar
- Neuroscience Institute, New York University Medical Center, New York, NY, 10016, USA.
- Department of Neuroscience and Physiology, New York University Medical Center, New York, NY, USA.
- Department of Psychology, University of Cambridge, Cambridge, UK.
- MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK.
| | - Simon R O Nilsson
- Neuroscience Institute, New York University Medical Center, New York, NY, 10016, USA
- Department of Neuroscience and Physiology, New York University Medical Center, New York, NY, USA
- Department of Psychology, University of Cambridge, Cambridge, UK
- MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
| | - Begoña Gamallo-Lana
- Neuroscience Institute, New York University Medical Center, New York, NY, 10016, USA
- Department of Neuroscience and Physiology, New York University Medical Center, New York, NY, USA
- Department of Psychology, University of Cambridge, Cambridge, UK
- MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
| | - Ming Lei
- Department of Psychology, University of Cambridge, Cambridge, UK
- MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
- Department of Health Industry Management, Beijing International Studies University, 1 Dingfuzhuang Nanli, Beijing, China
| | - Theda Dourado
- Department of Psychology, University of Cambridge, Cambridge, UK
- MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
| | - Johan Alsiö
- Department of Psychology, University of Cambridge, Cambridge, UK
- MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
- Department of Neuroscience, Unit of Functional Neurobiology, University of Uppsala, Uppsala, Sweden
| | - Lisa M Saksida
- Department of Psychology, University of Cambridge, Cambridge, UK
- MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
- Molecular Medicine Research Group, Robarts Research Institute, Western University, London, ON, Canada
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
- The Brain and Mind Institute, Western University, London, ON, Canada
| | - Timothy J Bussey
- Department of Psychology, University of Cambridge, Cambridge, UK
- MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
- Molecular Medicine Research Group, Robarts Research Institute, Western University, London, ON, Canada
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
- The Brain and Mind Institute, Western University, London, ON, Canada
| | - Trevor W Robbins
- Department of Psychology, University of Cambridge, Cambridge, UK
- MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
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Behavioural pharmacology of the α5-GABA A receptor antagonist S44819: Enhancement and remediation of cognitive performance in preclinical models. Neuropharmacology 2017; 125:30-38. [DOI: 10.1016/j.neuropharm.2017.07.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Revised: 07/04/2017] [Accepted: 07/06/2017] [Indexed: 11/24/2022]
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Chen X, Keramidas A, Lynch JW. Physiological and pharmacological properties of inhibitory postsynaptic currents mediated by α5β1γ2, α5β2γ2 and α5β3γ2 GABA A receptors. Neuropharmacology 2017; 125:243-253. [PMID: 28757051 DOI: 10.1016/j.neuropharm.2017.07.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 07/18/2017] [Accepted: 07/26/2017] [Indexed: 02/07/2023]
Abstract
α5-containing GABAARs are potential therapeutic targets for clinical conditions including age-related dementia, stroke, schizophrenia, Down syndrome, anaesthetic-induced amnesia, anxiety and pain. α5-containing GABAARs are expressed in layer 5 cortical neurons and hippocampal pyramidal neurons where they mediate both tonic currents and slow inhibitory postsynaptic currents (IPSCs). A range of drugs has been developed to specifically modulate these receptors. The main α5-containing GABAARs that are likely to exist in vivo are the α5β1γ2, α5β2γ2 and α5β3γ2 isoforms. We currently have few clues as to how these isoforms are distributed between synaptic and extrasynaptic compartments or their relative roles in controlling neuronal excitability. Accordingly, the aim of this study was to define the basic biophysical and pharmacological properties of IPSCs mediated by the three isoforms in a hippocampal neuron-HEK293 cell co-culture assay. The IPSC decay time constants were slow (α5β1γ2L: 45 ms; α5β1γ2L: 80 ms; α5β3γ2L: 184 ms) and were largely dominated by the intrinsic channel deactivation rates. By comparing IPSC rise times, we inferred that α5β1γ2L GABAARs are located postsynaptically whereas the other two are predominantly perisynaptic. α5β3γ2L GABAARs alone mediated tonic currents. We quantified the effects of four α5-specific inverse agonists (TB-21007, MRK-016, α5IA and L-655708) on IPSCs mediated by the three isoforms. All compounds selectively inhibited IPSC amplitudes and accelerated IPSC decay rates, albeit with distinct isoform specificities. MRK-016 also significantly accelerated IPSC rise times. These results provide a reference for future studies seeking to identify and characterize the properties of IPSCs mediated by α5-containing GABAAR isoforms in neurons.
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Affiliation(s)
- Xiumin Chen
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Angelo Keramidas
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Joseph W Lynch
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
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Vidal V, García-Cerro S, Martínez P, Corrales A, Lantigua S, Vidal R, Rueda N, Ozmen L, Hernández MC, Martínez-Cué C. Decreasing the Expression of GABA A α5 Subunit-Containing Receptors Partially Improves Cognitive, Electrophysiological, and Morphological Hippocampal Defects in the Ts65Dn Model of Down Syndrome. Mol Neurobiol 2017; 55:4745-4762. [PMID: 28717969 DOI: 10.1007/s12035-017-0675-3] [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: 03/30/2017] [Accepted: 06/27/2017] [Indexed: 12/31/2022]
Abstract
Trisomy 21 or Down syndrome (DS) is the most common cause of intellectual disability of a genetic origin. The Ts65Dn (TS) mouse, which is the most commonly used and best-characterized mouse model of DS, displays many of the cognitive, neuromorphological, and biochemical anomalies that are found in the human condition. One of the mechanisms that have been proposed to be responsible for the cognitive deficits in this mouse model is impaired GABA-mediated inhibition. Because of the well-known modulatory role of GABAA α5 subunit-containing receptors in cognitive processes, these receptors are considered to be potential targets for improving the intellectual disability in DS. The chronic administration of GABAA α5-negative allosteric modulators has been shown to be procognitive without anxiogenic or proconvulsant side effects. In the present study, we use a genetic approach to evaluate the contribution of GABAA α5 subunit-containing receptors to the cognitive, electrophysiological, and neuromorphological deficits in TS mice. We show that reducing the expression of GABAA α5 receptors by deleting one or two copies of the Gabra5 gene in TS mice partially ameliorated the cognitive impairments, improved long-term potentiation, enhanced neural differentiation and maturation, and normalized the density of the GABAergic synapse markers. Reducing the gene dosage of Gabra5 in TS mice did not induce motor alterations and anxiety or affect the viability of the mice. Our results provide further evidence of the role of GABAA α5 receptor-mediated inhibition in cognitive impairment in the TS mouse model of DS.
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Affiliation(s)
- Verónica Vidal
- Departamento de Fisiología y Farmacología, Facultad de Medicina, Universidad deCantabria, Santander, Spain
| | - Susana García-Cerro
- Departamento de Fundamentos Clínicos, Unidad de Farmacología, Universitat de Barcelona, Barcelona, Spain
| | - Paula Martínez
- Departamento de Fisiología y Farmacología, Facultad de Medicina, Universidad deCantabria, Santander, Spain
| | - Andrea Corrales
- Departamento de Fisiología y Farmacología, Facultad de Medicina, Universidad deCantabria, Santander, Spain
| | - Sara Lantigua
- Departamento de Fisiología y Farmacología, Facultad de Medicina, Universidad deCantabria, Santander, Spain
| | - Rebeca Vidal
- Departamento de Fisiología y Farmacología, Facultad de Medicina, Universidad deCantabria, Santander, Spain.,Instituto de Biomedicina y Biotecnología de Cantabria, IBBTEC (Universidad de Cantabria, CSIC, SODERCAN), Santander, Spain.,Centro de Investigacion Biomédica en Red de Salud Mental (CIBERSAM), Instituto de Salud Carlos III, Madrid, Spain
| | - Noemí Rueda
- Departamento de Fisiología y Farmacología, Facultad de Medicina, Universidad deCantabria, Santander, Spain
| | - Laurence Ozmen
- Pharma Research and Early Development, Hoffman-La Roche Ltd., Basel, Switzerland
| | | | - Carmen Martínez-Cué
- Departamento de Fisiología y Farmacología, Facultad de Medicina, Universidad deCantabria, Santander, Spain.
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Bast T, Pezze M, McGarrity S. Cognitive deficits caused by prefrontal cortical and hippocampal neural disinhibition. Br J Pharmacol 2017; 174:3211-3225. [PMID: 28477384 DOI: 10.1111/bph.13850] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 03/18/2017] [Accepted: 05/03/2017] [Indexed: 12/22/2022] Open
Abstract
We review recent evidence concerning the significance of inhibitory GABA transmission and of neural disinhibition, that is, deficient GABA transmission, within the prefrontal cortex and the hippocampus, for clinically relevant cognitive functions. Both regions support important cognitive functions, including attention and memory, and their dysfunction has been implicated in cognitive deficits characterizing neuropsychiatric disorders. GABAergic inhibition shapes cortico-hippocampal neural activity, and, recently, prefrontal and hippocampal neural disinhibition has emerged as a pathophysiological feature of major neuropsychiatric disorders, especially schizophrenia and age-related cognitive decline. Regional neural disinhibition, disrupting spatio-temporal control of neural activity and causing aberrant drive of projections, may disrupt processing within the disinhibited region and efferent regions. Recent studies in rats showed that prefrontal and hippocampal neural disinhibition (by local GABA antagonist microinfusion) dysregulates burst firing, which has been associated with important aspects of neural information processing. Using translational tests of clinically relevant cognitive functions, these studies showed that prefrontal and hippocampal neural disinhibition disrupts regional cognitive functions (including prefrontal attention and hippocampal memory function). Moreover, hippocampal neural disinhibition disrupted attentional performance, which does not require the hippocampus but requires prefrontal-striatal circuits modulated by the hippocampus. However, some prefrontal and hippocampal functions (including inhibitory response control) are spared by regional disinhibition. We consider conceptual implications of these findings, regarding the distinct relationships of distinct cognitive functions to prefrontal and hippocampal GABA tone and neural activity. Moreover, the findings support the proposition that prefrontal and hippocampal neural disinhibition contributes to clinically relevant cognitive deficits, and we consider pharmacological strategies for ameliorating cognitive deficits by rebalancing disinhibition-induced aberrant neural activity. Linked Articles This article is part of a themed section on Pharmacology of Cognition: a Panacea for Neuropsychiatric Disease? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.19/issuetoc.
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Affiliation(s)
- Tobias Bast
- School of Psychology and Neuroscience @Nottingham, University of Nottingham, Nottingham, UK
| | - Marie Pezze
- School of Psychology and Neuroscience @Nottingham, University of Nottingham, Nottingham, UK
| | - Stephanie McGarrity
- School of Psychology and Neuroscience @Nottingham, University of Nottingham, Nottingham, UK
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A Negative Allosteric Modulator for α5 Subunit-Containing GABA Receptors Exerts a Rapid and Persistent Antidepressant-Like Action without the Side Effects of the NMDA Receptor Antagonist Ketamine in Mice. eNeuro 2017; 4:eN-NWR-0285-16. [PMID: 28275719 PMCID: PMC5334634 DOI: 10.1523/eneuro.0285-16.2017] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 01/31/2017] [Accepted: 02/10/2017] [Indexed: 02/06/2023] Open
Abstract
New antidepressant pharmacotherapies that provide rapid relief of depressive symptoms are needed. The NMDA receptor antagonist ketamine exerts rapid antidepressant actions in depressed patients but also side effects that complicate its clinical utility. Ketamine promotes excitatory synaptic strength, likely by producing high-frequency correlated activity in mood-relevant regions of the forebrain. Negative allosteric modulators of GABA-A receptors containing α5 subunits (α5 GABA-NAMs) should also promote high-frequency correlated electroencephalogram (EEG) activity and should therefore exert rapid antidepressant responses. Because α5 subunits display a restricted expression in the forebrain, we predicted that α5 GABA-NAMs would produce activation of principle neurons but exert fewer side effects than ketamine. We tested this hypothesis in male mice and observed that the α5 GABA-NAM MRK-016 exerted an antidepressant-like response in the forced swim test at 1 and 24 h after administration and an anti-anhedonic response after chronic stress in the female urine sniffing test (FUST). Like ketamine, MRK-016 produced a transient increase in EEG γ power, and both the increase in γ power and its antidepressant effects in the forced swim test were blocked by prior administration of the AMPA-type glutamate receptor antagonist 2,3-dioxo-6-nitro-1,2,3,4-tetrahydrobenzo[f]quinoxaline-7-sulfonamide (NBQX). Unlike ketamine, however, MRK-016 produced no impairment of rota-rod performance, no reduction of prepulse inhibition (PPI), no conditioned-place preference (CPP), and no change in locomotion. α5 GABA-NAMs, thus reproduce the rapid antidepressant-like actions of ketamine, perhaps via an AMPA receptor (AMPAR)-dependent increase in coherent neuronal activity, but display fewer potential negative side effects. These compounds thus demonstrate promise as clinically useful fast-acting antidepressants.
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Contestabile A, Magara S, Cancedda L. The GABAergic Hypothesis for Cognitive Disabilities in Down Syndrome. Front Cell Neurosci 2017; 11:54. [PMID: 28326014 PMCID: PMC5339239 DOI: 10.3389/fncel.2017.00054] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 02/14/2017] [Indexed: 12/04/2022] Open
Abstract
Down syndrome (DS) is a genetic disorder caused by the presence of a third copy of chromosome 21. DS affects multiple organs, but it invariably results in altered brain development and diverse degrees of intellectual disability. A large body of evidence has shown that synaptic deficits and memory impairment are largely determined by altered GABAergic signaling in trisomic mouse models of DS. These alterations arise during brain development while extending into adulthood, and include genesis of GABAergic neurons, variation of the inhibitory drive and modifications in the control of neural-network excitability. Accordingly, different pharmacological interventions targeting GABAergic signaling have proven promising preclinical approaches to rescue cognitive impairment in DS mouse models. In this review, we will discuss recent data regarding the complex scenario of GABAergic dysfunctions in the trisomic brain of DS mice and patients, and we will evaluate the state of current clinical research targeting GABAergic signaling in individuals with DS.
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Affiliation(s)
- Andrea Contestabile
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia (IIT) Genova, Italy
| | - Salvatore Magara
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia (IIT) Genova, Italy
| | - Laura Cancedda
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia (IIT)Genova, Italy; Dulbecco Telethon InstituteGenova, Italy
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Effects of Traumatic Stress Induced in the Juvenile Period on the Expression of Gamma-Aminobutyric Acid Receptor Type A Subunits in Adult Rat Brain. Neural Plast 2017; 2017:5715816. [PMID: 28352479 PMCID: PMC5352903 DOI: 10.1155/2017/5715816] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 01/18/2017] [Accepted: 02/15/2017] [Indexed: 12/04/2022] Open
Abstract
Studies have found that early traumatic experience significantly increases the risk of posttraumatic stress disorder (PTSD). Gamma-aminobutyric acid (GABA) deficits were proposed to be implicated in development of PTSD, but the alterations of GABA receptor A (GABAAR) subunits induced by early traumatic stress have not been fully elucidated. Furthermore, previous studies suggested that exercise could be more effective than medications in reducing severity of anxiety and depression but the mechanism is unclear. This study used inescapable foot-shock to induce PTSD in juvenile rats and examined their emotional changes using open-field test and elevated plus maze, memory changes using Morris water maze, and the expression of GABAAR subunits (γ2, α2, and α5) in subregions of the brain in the adulthood using western blotting and immunohistochemistry. We aimed to observe the role of GABAAR subunits changes induced by juvenile trauma in the pathogenesis of subsequent PTSD in adulthood. In addition, we investigated the protective effects of exercise for 6 weeks and benzodiazepine (clonazepam) for 2 weeks. This study found that juvenile traumatic stress induced chronic anxiety and spatial memory loss and reduced expression of GABAAR subunits in the adult rat brains. Furthermore, exercise led to significant improvement as compared to short-term BZ treatment.
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Abstract
Learning and memory are dependent on interactive excitatory and inhibitory mechanisms. In this review, we discuss a mechanism called disinhibition, which is the release of an inhibitory constraint that effectively results in an increased activity in the target neurons (for example, principal or projection neurons). We focus on discussing the role of disinhibition in learning and memory at a basic level and in disease models with cognitive deficits and highlight a strategy to reverse cognitive deficits caused by excess inhibition, through disinhibition of α5-containing GABA
A receptors mediating tonic inhibition in the hippocampus, based on subtype-selective negative allosteric modulators as a novel class of drugs.
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Affiliation(s)
- Hanns Möhler
- Institute of Pharmacology, University of Zurich, Zurich, Switzerland; Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology Zurich, Zurich, Switzerland
| | - Uwe Rudolph
- Laboratory of Genetic Neuropharmacology, McLean Hospital, Belmont, MA, USA; Department of Psychiatry, Harvard Medical School, Boston, MA, USA
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Coelho VR, Sousa K, Pires TR, Papke DKM, Vieira CG, de Souza LP, Leal MB, Schunck RVA, Picada JN, Pereira P. Genotoxic and mutagenic effects of vigabatrin, a γ-aminobutyric acid transaminase inhibitor, in Wistar rats submitted to rotarod task. Hum Exp Toxicol 2016; 35:958-65. [DOI: 10.1177/0960327115611970] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Vigabatrin (VGB) is an antiepileptic drug thatincreases brain γ-aminobutyric acid (GABA) levels through irreversible inhibition of GABA transaminase. The aim of this study was to evaluate neurotoxicological effects of VGB measuring motor activity and genotoxic and mutagenic effects after a single and repeated administration. Male Wistar rats received saline, VGB 50, 100, or 250 mg/kg by gavage for acute and subchronic (14 days) treatments and evaluated in the rotarod task. Genotoxicity was evaluated using the alkaline version of the comet assay in samples of blood, liver, hippocampus, and brain cortex after both treatments. Mutagenicity was evaluated using the micronucleus test in bone marrow of the same animals that received subchronic treatment. The groups treated with VGB showed similar performance in rotarod compared with the saline group. Regarding the acute treatment, it was observed that only higher VGB doses induced DNA damage in blood and hippocampus. After the subchronic treatment, VGB did not show genotoxic or mutagenic effects. In brief, VGB did not impair motor activities in rats after acute and subchronic treatments. It showed a repairable genotoxic potential in the central nervous system since genotoxicity was observed in the acute treatment group.
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Affiliation(s)
- VR Coelho
- Laboratory of Neuropharmacology and Preclinical Toxicology, Department of Pharmacology, Institute of Basic Health Sciences, Federal University of Rio Grande doSul, Porto Alegre, Brazil
| | - K Sousa
- Laboratory of Genetic Toxicology, Lutheran University of Brazil, Canoas, Brazil
| | - TR Pires
- Laboratory of Genetic Toxicology, Lutheran University of Brazil, Canoas, Brazil
| | - DKM Papke
- Laboratory of Genetic Toxicology, Lutheran University of Brazil, Canoas, Brazil
| | - CG Vieira
- Laboratory of Neuropharmacology and Preclinical Toxicology, Department of Pharmacology, Institute of Basic Health Sciences, Federal University of Rio Grande doSul, Porto Alegre, Brazil
| | - LP de Souza
- Laboratory of Neuropharmacology and Preclinical Toxicology, Department of Pharmacology, Institute of Basic Health Sciences, Federal University of Rio Grande doSul, Porto Alegre, Brazil
| | - MB Leal
- Laboratory of Pharmacology and Toxicology of Natural Products, Department of Pharmacology, Institute of Basic Health Sciences, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - RVA Schunck
- Laboratory of Pharmacology and Toxicology of Natural Products, Department of Pharmacology, Institute of Basic Health Sciences, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - JN Picada
- Laboratory of Genetic Toxicology, Lutheran University of Brazil, Canoas, Brazil
| | - P Pereira
- Laboratory of Neuropharmacology and Preclinical Toxicology, Department of Pharmacology, Institute of Basic Health Sciences, Federal University of Rio Grande doSul, Porto Alegre, Brazil
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Abstract
UNLABELLED Tonic GABA currents mediated by high-affinity extrasynaptic GABAA receptors, are increasingly recognized as important regulators of cell and neuronal network excitability. Dysfunctional GABAA receptor signaling that results in modified tonic GABA currents is associated with a number of neurological disorders. Consequently, developing compounds to selectively modulate the activity of extrasynaptic GABAA receptors underlying tonic inhibition is likely to prove therapeutically useful. Here, we examine the GABAA receptor subtype selectivity of the weak partial agonist, 5-(4-piperidyl)isoxazol-3-ol (4-PIOL), as a potential mechanism for modulating extrasynaptic GABAA receptor-mediated tonic currents. By using recombinant GABAA receptors expressed in HEK293 cells, and native GABAA receptors of cerebellar granule cells, hippocampal neurons, and thalamic relay neurons, 4-PIOL evidently displayed differential agonist and antagonist-type profiles, depending on the extrasynaptic GABAA receptor isoforms targeted. For neurons, this resulted in differential modulation of GABA tonic currents, depending on the cell type studied, their respective GABAA receptor subunit compositions, and critically, on the ambient GABA levels. Unexpectedly, 4-PIOL revealed a significant population of relatively low-affinity γ2 subunit-containing GABAA receptors in the thalamus, which can contribute to tonic inhibition under specific conditions when GABA levels are raised. Together, these data indicate that partial agonists, such as 4-PIOL, may be useful for modulating GABAA receptor-mediated tonic currents, but the direction and extent of this modulation is strongly dependent on relative expression levels of different extrasynaptic GABAA receptor subtypes, and on the ambient GABA levels. SIGNIFICANCE STATEMENT A background level of inhibition (tonic) is important in the brain for controlling neuronal excitability. Increased levels of tonic inhibition are associated with some neurological disorders but there are no specific ligands capable of selectively reducing tonic inhibition. Here we explore the use of a GABA partial agonist as a selective chemical tool in three different brain regions. We discover that the activity of a partial agonist is heavily dependent upon the GABAA receptor subunit composition underpinning tonic inhibition, and on the ambient levels of GABA in the brain.
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Zuiker RGJA, Chen X, Østerberg O, Mirza NR, Muglia P, de Kam M, Klaassen ES, van Gerven JMA. NS11821, a partial subtype-selective GABAA agonist, elicits selective effects on the central nervous system in randomized controlled trial with healthy subjects. J Psychopharmacol 2016; 30:253-62. [PMID: 26655084 DOI: 10.1177/0269881115620435] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
NS11821 is a partial GABAA agonist with relatively dominant α2,3 and α5 subtype efficacy but negligible α1 agonism. This first-in-human study was performed in healthy male subjects using a single-dose, parallel, double blind, placebo-controlled, randomized, dose-escalation study design. In total six cohorts (N=48) were enrolled. The eight subjects of each cohort received NS11821 (10 mg, 30 mg, 75 mg, 150 mg, 300 mg or 600 mg) or placebo in a 6:2 ratio. At low dose levels, NS11821 had a relatively low exposure and a more-than-proportional increase of the area under the curve and maximum plasma concentrations, probably due to poor solubility. Saccadic peak velocity decreased in a dose-related manner while limited impairments were seen on body sway and the visual analogue scale for alertness. The most common adverse events were somnolence and dizziness, which were more prominent with the higher doses. Although no positive control was used in this study, the results were compared post hoc with a Centre for Human Drug Research dataset for lorazepam 2 mg. The maximum saccadic peak velocity effects seemed comparable to the typical effects of lorazepam, whereas the other central nervous system effects were smaller. These results support the pharmacological selectivity of NS11821 and show that pharmacodynamic effective doses of NS11821 were safe and well tolerated in healthy subjects.
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Affiliation(s)
| | - Xia Chen
- Centre for Human Drug Research (CHDR), Leiden, the Netherlands Clinical Pharmacological Research Centre (CPRC), Peking Union Medical College Hospital, Beijing, PR China
| | | | | | | | - Marieke de Kam
- Centre for Human Drug Research (CHDR), Leiden, the Netherlands
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