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Aranđelović J, Santrač A, Batinić B, Todorović L, Stevanović V, Tiruveedhula VVNPB, Sharmin D, Rashid F, Stanojević B, Cook JM, Savić MM. Effects of α5 GABA A receptor modulation on social interaction, memory, and neuroinflammation in a mouse model of Alzheimer's disease. CNS Neurosci Ther 2022; 28:1767-1778. [PMID: 35822698 PMCID: PMC9532908 DOI: 10.1111/cns.13914] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 06/08/2022] [Accepted: 06/21/2022] [Indexed: 12/24/2022] Open
Abstract
AIMS GABAergic modulation involved in cognitive processing appears to be substantially changed in Alzheimer's disease (AD). In a widely used 5xFAD model of AD, we aimed to assess if negative and positive allosteric modulators of α5 GABAA receptors (NAM and PAM, respectively) would affect social interaction, social, object and spatial memory, and neuroinflammation. METHODS After 10-day treatment with PAM, NAM, or solvent, 6-month-old transgenic and non-transgenic 5xFAD mice underwent testing in a behavioral battery. Gene expressions of IL-1β, IL-6, TNF-α, GFAP, and IBA-1 were determined in hippocampus and prefrontal cortex by qPCR. RESULTS PAM treatment impaired spatial learning in transgenic females compared to solvent-treated transgenic females, and social recognition in transgenic and non-transgenic males. NAM treatment declined social interaction in transgenic and non-transgenic males, while had beneficial effect on cognitive flexibility in non-transgenic males compared to solvent-treated non-transgenic males. Transgenic animals have not fully displayed cognitive symptoms, but neuroinflammation was confirmed. NAM reduced proinflammatory gene expressions in transgenic females and astrogliosis in transgenic males compared to pathological controls. CONCLUSION PAM and NAM failed to exert favorable behavioral effects in transgenic animals. Suppression of neuroinflammation obtained with NAM calls for more studies with GABAergic ligands in amyloid beta- and/or tau-dependent models with prominent neuroinflammation.
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Affiliation(s)
- Jovana Aranđelović
- Department of Pharmacology, Faculty of PharmacyUniversity of BelgradeBelgradeSerbia
| | - Anja Santrač
- Department of Pharmacology, Faculty of PharmacyUniversity of BelgradeBelgradeSerbia
| | - Bojan Batinić
- Department of Physiology, Faculty of PharmacyUniversity of BelgradeBelgradeSerbia
| | - Lidija Todorović
- Laboratory for Radiobiology and Molecular Genetics, Vinča Institute of Nuclear Sciences, National Institute of thе Republic of SerbiaUniversity of BelgradeBelgradeSerbia
| | - Vladimir Stevanović
- Department of Pharmacology, Faculty of PharmacyUniversity of BelgradeBelgradeSerbia
| | | | - Dishary Sharmin
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug DiscoveryUniversity of Wisconsin‐MilwaukeeMilwaukeeWisconsinUSA
| | - Farjana Rashid
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug DiscoveryUniversity of Wisconsin‐MilwaukeeMilwaukeeWisconsinUSA
| | - Boban Stanojević
- Laboratory for Radiobiology and Molecular Genetics, Vinča Institute of Nuclear Sciences, National Institute of thе Republic of SerbiaUniversity of BelgradeBelgradeSerbia
- Comprehensive Cancer Centre, Faculty of Life Sciences & Medicine, King's College LondonRayne InstituteLondonUK
| | - James M. Cook
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug DiscoveryUniversity of Wisconsin‐MilwaukeeMilwaukeeWisconsinUSA
| | - Miroslav M. Savić
- Department of Pharmacology, Faculty of PharmacyUniversity of BelgradeBelgradeSerbia
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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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Aranđelović J, Santrač A, Batinić B, Todorović L, Ahmed Khan MZ, Rashid F, Poe MM, Obradović A, Cook JM, Savić MM. Positive and Negative Selective Allosteric Modulators of α5 GABAA Receptors: Effects on Emotionality, Motivation, and Motor Function in the 5xFAD Model of Alzheimer's Disease. J Alzheimers Dis 2021; 84:1291-1302. [PMID: 34657887 DOI: 10.3233/jad-215079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Positive and negative allosteric modulators of α5 GABAA receptors (PAM and NAM, respectively) are worthy of investigation as putative treatments of Alzheimer's disease (AD). However, their potential to modify a dynamic range of behaviors in AD models needs to be systematically examined. OBJECTIVE The study aimed to assess effects of MP-III-022 as PAM and PWZ-029 as NAM on emotional reactivity, motivation, and motor function, as well as on gene expression of GABRA2, GABRA3 and GABRA5 subunit of GABAA receptors in prefrontal cortex (PFC) and hippocampus (HC) in 5xFAD mice, as an early-onset transgenic AD model. METHODS The 6-month-old 5xFAD transgenic and non-transgenic mice of both genders underwent a battery of reflexes and behavioral tests (sensorimotor tests, elevated plus maze, and open field) after 10-day intraperitoneal treatment with MP-III-022, PWZ-029, or solvent. The behavioral battery was followed by qPCR analysis of gene expression. RESULTS MP-III-022 induced a decline in motor function, while PWZ-029 further decreased emotionality of transgenic males, as compared to the transgenic control. No interfering effects on non-cognitive behavior were observed in female mice. In HC, both treatments reversed reciprocal GABRA2 and GABRA3 changes in transgenic females. In PFC, MP-III-022 decreased GABRA5 in both genders, while PWZ-029 increased GABRA2 in male transgenic animals. CONCLUSION Gender-dependent protracted effects of PAMs and NAMs in AD model, with detrimental impact on motor capabilities of PAM, and attenuation of emotionality elicited by NAM in transgenic males, were revealed. This favors future research of α5 GABAA receptor modulation in females as more promising.
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Affiliation(s)
- Jovana Aranđelović
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - Anja Santrač
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - Bojan Batinić
- Department of Physiology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - Lidija Todorović
- Laboratory for Radiobiology and Molecular Genetics, Vinca Institute of Nuclear Sciences, National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Md Zubair Ahmed Khan
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Farjana Rashid
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Michael M Poe
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Aleksandar Obradović
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - James M Cook
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Miroslav M Savić
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
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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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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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Mitrović JR, Divović B, Knutson DE, Đoković JB, Vulić PJ, Randjelović DV, Dobričić VD, Čalija BR, Cook JM, Savić MM, Savić SD. Nanocrystal dispersion of DK-I-56-1, a poorly soluble pyrazoloquinolinone positive modulator of α6 GABAA receptors: Formulation approach toward improved in vivo performance. Eur J Pharm Sci 2020; 152:105432. [PMID: 32565331 DOI: 10.1016/j.ejps.2020.105432] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Revised: 06/03/2020] [Accepted: 06/17/2020] [Indexed: 12/17/2022]
Abstract
DK-I-56-1 (7‑methoxy‑2-(4‑methoxy‑d3-phenyl)-2,5-dihydro-3H-pyrazolo[4,3-c]quinolin-3-one), a recently developed deuterated pyrazoloquinolinone, has been recognized as a lead candidate for treatment of various neuropsychiatric disorders. During preclinical investigation of poorly water-soluble compounds such as DK-I-56-1, the application of nanotechnology could be advantageous due to improved safety and possibly increased bioavailability of nanosized formulation. DK-I-56-1 nanosuspensions stabilized by polysorbate 80, alone or in combination with poloxamers 188 i.e. 407 or d-α-tocopheryl polyethylene glycol 1000 succinate, were prepared using a small-scale media milling device. With particle size 208.7-250.6 nm and polydispersity index <0.250, selected nanodiseprsions were stable for three weeks. Pharmacokinetic and biodistribution studies following intraperitoneal administration of three types of formulation in mice indicated high plasma DK-I-56-1 levels after solution (10,228.6 ± 1037.2 ngh/ml) and nanosuspension (6770.4 ± 770.7 ngh/ml) but not suspension administration (966.0 ± 58.1 ngh/ml). However, distribution of DK-I-56-1 after solution was heavily influenced by its composition, and brain availability of nanosuspension was superior to that of solution formulation. In spontaneous locomotor activity test, the expected hyperlocomotor effect was observed after nanosuspension administration, without compromising impact of the vehicle/excipients used. Therefore, nanonization of drug compound assembled with proper selection of stabilizers may seemingly contribute further thorough testing of DK-I-56-1 preclinical efficacy.
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Affiliation(s)
- Jelena R Mitrović
- Department of Pharmaceutical Technology and Cosmetology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia.
| | - Branka Divović
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia.
| | - Daniel E Knutson
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, 3210N. Cramer St., Milwaukee, WI 53211, USA.
| | - Jelena B Đoković
- Department of Pharmaceutical Technology and Cosmetology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia.
| | - Predrag J Vulić
- Laboratory of Crystallography, Faculty of Mining and Geology, University of Belgrade, Đušina 7, 11000 Belgrade, Serbia.
| | - Danijela V Randjelović
- Department of Microelectronic Technologies, Institute of Chemistry, Technology and Metallurgy, University of Belgrade, Njegoševa 12, 11000 Belgrade, Serbia.
| | - Vladimir D Dobričić
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia.
| | - Bojan R Čalija
- Department of Pharmaceutical Technology and Cosmetology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia.
| | - James M Cook
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, 3210N. Cramer St., Milwaukee, WI 53211, USA.
| | - Miroslav M Savić
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia.
| | - Snežana D Savić
- Department of Pharmaceutical Technology and Cosmetology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia.
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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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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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10
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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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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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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: 68] [Impact Index Per Article: 11.3] [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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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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14
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Li G, Stephen MR, Kodali R, Zahn NM, Poe MM, Tiruveedhula VVNPB, Huber AT, Schussman MK, Qualmann K, Panhans CM, Raddatz NJ, Baker DA, Prevot TD, Banasr M, Sibille E, Arnold LA, Cook JM. Synthesis of chiral GABA A receptor subtype selective ligands as potential agents to treat schizophrenia as well as depression. ARKIVOC 2018; 2018:158-182. [PMID: 32774192 PMCID: PMC7413308 DOI: 10.24820/ark.5550190.p010.460] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
A series of novel imidazobenzodiazepine analogs of the lead chiral ligand SH-053-2'F-S-CH3 (2), an α2/α3/α5 (Bz)GABA (A)ergic receptor subtype selective ligand, which reversed PCP-induced prepulse inhibition (PPI) of acoustic startle, were synthesized. These chiral (S)-CH3 ligands are targeted for the treatment of schizophrenia and depression. These new ligands were designed by modifying the liable ester functionality in 2 to improve the metabolic stability, cytotoxicity, and activity as compared to 2. Based on the data to date, the most promising ligands are the N-cyclopropyl amide GL-I-55 (8c) and the methyl bioisostere GL-I-65 (9a). The in vitro metabolic stability, cytotoxicity and in vivo locomotor effects are described in this report. Based on these results, 8c and 9a are the most promising for further in vivo pharmacology.
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Affiliation(s)
- Guanguan Li
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, United States
| | - Michael R Stephen
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, United States
| | - Revathi Kodali
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, United States
| | - Nicolas M Zahn
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, United States
| | - Michael M Poe
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, United States
| | - V V N Phani Babu Tiruveedhula
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, United States
| | - Alec T Huber
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, United States
| | - Melissa K Schussman
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, United States
| | - Krista Qualmann
- Department of Biomedical Science, Marquette University, Milwaukee, Wisconsin 53233, United States
| | - Cristina M Panhans
- Department of Biomedical Science, Marquette University, Milwaukee, Wisconsin 53233, United States
| | - Nicholas J Raddatz
- Department of Biomedical Science, Marquette University, Milwaukee, Wisconsin 53233, United States
| | - David A Baker
- Department of Biomedical Science, Marquette University, Milwaukee, Wisconsin 53233, United States
| | - Thomas D Prevot
- Campbell Family Mental Health Research Institute of CAMH, Toronto, Canada
| | - Mounira Banasr
- Campbell Family Mental Health Research Institute of CAMH, Toronto, Canada
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Canada
- Department of Psychiatry, University of Toronto, Toronto, Canada
| | - Etienne Sibille
- Campbell Family Mental Health Research Institute of CAMH, Toronto, Canada
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Canada
- Department of Psychiatry, University of Toronto, Toronto, Canada
| | - Leggy A Arnold
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, United States
| | - James M Cook
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, United States
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15
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Meyer MAA, Corcoran KA, Chen HJ, Gallego S, Li G, Tiruveedhula VV, Cook JM, Radulovic J. Neurobiological correlates of state-dependent context fear. ACTA ACUST UNITED AC 2017; 24:385-391. [PMID: 28814463 PMCID: PMC5580530 DOI: 10.1101/lm.045542.117] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 06/07/2017] [Indexed: 12/02/2022]
Abstract
Retrieval of fear memories can be state-dependent, meaning that they are best retrieved if the brain states at encoding and retrieval are similar. Such states can be induced by activating extrasynaptic γ-aminobutyric acid type A receptors (GABAAR) with the broad α-subunit activator gaboxadol. However, the circuit mechanisms and specific subunits underlying gaboxadol's effects are not well understood. Here we show that gaboxadol induces profound changes of local and network oscillatory activity, indicative of discoordinated hippocampal–cortical activity, that were accompanied by robust and long-lasting state-dependent conditioned fear. Episodic memories typically are hippocampus-dependent for a limited period after learning, but become cortex-dependent with the passage of time. In contrast, state-dependent memories continued to rely on hippocampal GABAergic mechanisms for memory retrieval. Pharmacological approaches with α-subunit-specific agonists targeting the hippocampus implicated the prototypic extrasynaptic subunits (α4) as the mediator of state-dependent conditioned fear. Together, our findings suggest that continued dependence on hippocampal rather than cortical mechanisms could be an important feature of state-dependent memories that contributes to their conditional retrieval.
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Affiliation(s)
- Mariah A A Meyer
- Department of Psychiatry and Behavioral Sciences, Northwestern University, Chicago, Illinois 60611, USA
| | - Kevin A Corcoran
- Department of Psychiatry and Behavioral Sciences, Northwestern University, Chicago, Illinois 60611, USA
| | - Helen J Chen
- Department of Psychiatry and Behavioral Sciences, Northwestern University, Chicago, Illinois 60611, USA
| | - Sonia Gallego
- Department of Psychiatry and Behavioral Sciences, Northwestern University, Chicago, Illinois 60611, USA
| | - Guanguan Li
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, USA
| | - Veda V Tiruveedhula
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, USA
| | - James M Cook
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, USA
| | - Jelena Radulovic
- Department of Psychiatry and Behavioral Sciences, Northwestern University, Chicago, Illinois 60611, USA
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16
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Fischer BD, Schlitt RJ, Hamade BZ, Rehman S, Ernst M, Poe MM, Li G, Kodali R, Arnold LA, Cook JM. Pharmacological and antihyperalgesic properties of the novel α2/3 preferring GABA A receptor ligand MP-III-024. Brain Res Bull 2017; 131:62-69. [PMID: 28267561 PMCID: PMC5501353 DOI: 10.1016/j.brainresbull.2017.03.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 03/01/2017] [Indexed: 12/11/2022]
Abstract
γ-Aminobutyric acid type A (GABAA) receptors are located in spinal nociceptive circuits where they modulate the transmission of pain sensory signals from the periphery to higher centers. Benzodiazepine-type drugs bind to GABAA receptors containing α1, α2, α3, and α5 subunits (α1GABAA, α2GABAA, α3GABAA and α5GABAA receptors, respectively) through which they inhibit the transmission of these signals. In the present study we describe the novel benzodiazepine site positive allosteric modulator modulator methyl 8-ethynyl-6-(pyridin-2-yl)-4H-benzo[f]imidazo[1,5-a][1,4]diazepine-3-carboxylate (MP-III-024). MP-III-024 displayed preference for α2GABAA and α3GABAA receptors relative to α1GABAA and α5GABAA receptors as well as an improved metabolic profile relative to subtype-selective positive modulators that are available currently. Administration of MP-III-024 resulted in a dose- and time-dependent reversal of mechanical hyperalgesia. On locomotor activity and schedule-controlled responding, MP-III-024 was ineffective across the doses tested. These data provide further evidence that α2GABAA and α3GABAA receptors play an important role in the antihyperalgesic effects and may not be involved in some of the undesired effects of benzodiazepine-like drugs. Further, these findings suggest that MP-III-024 is a suitable research tool for investigating the role of α2GABAA and α3GABAA receptors in the behavioral properties of benzodiazepine-like drugs in mice.
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Affiliation(s)
- Bradford D Fischer
- Cooper Medical School of Rowan University, Department of Biomedical Sciences Camden, NJ 08103, USA.
| | - Raymond J Schlitt
- Cooper Medical School of Rowan University, Department of Biomedical Sciences Camden, NJ 08103, USA
| | - Bryan Z Hamade
- Cooper Medical School of Rowan University, Department of Biomedical Sciences Camden, NJ 08103, USA
| | - Sabah Rehman
- Medical University of Vienna, Department of Molecular Neurosciences, 1090 Vienna, Austria
| | - Margot Ernst
- Medical University of Vienna, Department of Molecular Neurosciences, 1090 Vienna, Austria
| | - Michael M Poe
- University of Wisconsin-Milwaukee, Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, Milwaukee, WI 53201, USA
| | - Guanguan Li
- University of Wisconsin-Milwaukee, Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, Milwaukee, WI 53201, USA
| | - Revathi Kodali
- University of Wisconsin-Milwaukee, Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, Milwaukee, WI 53201, USA
| | - Leggy A Arnold
- University of Wisconsin-Milwaukee, Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, Milwaukee, WI 53201, USA
| | - James M Cook
- University of Wisconsin-Milwaukee, Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, Milwaukee, WI 53201, USA
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17
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A Review of the Updated Pharmacophore for the Alpha 5 GABA(A) Benzodiazepine Receptor Model. INTERNATIONAL JOURNAL OF MEDICINAL CHEMISTRY 2015; 2015:430248. [PMID: 26682068 PMCID: PMC4657098 DOI: 10.1155/2015/430248] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 06/16/2015] [Accepted: 07/02/2015] [Indexed: 12/22/2022]
Abstract
An updated model of the GABA(A) benzodiazepine receptor pharmacophore of the α5-BzR/GABA(A) subtype has been constructed prompted by the synthesis of subtype selective ligands in light of the recent developments in both ligand synthesis, behavioral studies, and molecular modeling studies of the binding site itself. A number of BzR/GABA(A) α5 subtype selective compounds were synthesized, notably α5-subtype selective inverse agonist PWZ-029 (1) which is active in enhancing cognition in both rodents and primates. In addition, a chiral positive allosteric modulator (PAM), SH-053-2′F-R-CH3 (2), has been shown to reverse the deleterious effects in the MAM-model of schizophrenia as well as alleviate constriction in airway smooth muscle. Presented here is an updated model of the pharmacophore for α5β2γ2 Bz/GABA(A) receptors, including a rendering of PWZ-029 docked within the α5-binding pocket showing specific interactions of the molecule with the receptor. Differences in the included volume as compared to α1β2γ2, α2β2γ2, and α3β2γ2 will be illustrated for clarity. These new models enhance the ability to understand structural characteristics of ligands which act as agonists, antagonists, or inverse agonists at the Bz BS of GABA(A) receptors.
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18
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Stamenić TT, Joksimović S, Biawat P, Stanković T, Marković B, Cook JM, Savić MM. Negative modulation of α₅ GABAA receptors in rats may partially prevent memory impairment induced by MK-801, but not amphetamine- or MK-801-elicited hyperlocomotion. J Psychopharmacol 2015; 29:1013-24. [PMID: 26105958 PMCID: PMC4861997 DOI: 10.1177/0269881115590601] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Reportedly, negative modulation of α5 GABAA receptors may improve cognition in normal and pharmacologically-impaired animals, and such modulation has been proposed as an avenue for treatment of cognitive symptoms in schizophrenia. This study assessed the actions of PWZ-029, administered at doses (2, 5, and 10 mg/kg) at which it reached micromolar concentrations in brain tissue with estimated free concentrations adequate for selective modulation of α5 GABAA receptors, in three cognitive tasks in male Wistar rats acutely treated with the noncompetitive N-methyl-d-aspartate receptor antagonist, MK-801 (0.1 mg/kg), as well in tests of locomotor activity potentiated by MK-801 (0.2 mg/kg) or amphetamine (0.5 mg/kg). In a hormetic-like manner, only 5 mg/kg PWZ-029 reversed MK-801-induced deficits in novel object recognition test (visual recognition memory), whereas in the Morris water maze, the 2 mg/kg dose of PWZ-029 exerted partial beneficial effects on spatial learning impairment. PWZ-029 did not affect recognition memory deficits in social novelty discrimination procedure. Motor hyperactivity induced with MK-801 or amphetamine was not preventable by PWZ-029. Our results show that certain MK-801-induced memory deficits can be ameliorated by negative modulation of α5 GABAA receptors, and point to the need for further elucidation of their translational relevance to cognitive deterioration in schizophrenia.
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Affiliation(s)
| | - Srdjan Joksimović
- Department of Pharmacology, University of Belgrade, Belgrade, Serbia
| | - Poonam Biawat
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Tamara Stanković
- Department of Pharmacology, University of Belgrade, Belgrade, Serbia
| | - Bojan Marković
- Department of Pharmaceutical Chemistry, University of Belgrade, Belgrade, Serbia
| | - James M Cook
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Miroslav M Savić
- Department of Pharmacology, University of Belgrade, Belgrade, Serbia
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19
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Botta P, Demmou L, Kasugai Y, Markovic M, Xu C, Fadok JP, Lu T, Poe MM, Xu L, Cook JM, Rudolph U, Sah P, Ferraguti F, Lüthi A. Regulating anxiety with extrasynaptic inhibition. Nat Neurosci 2015; 18:1493-500. [PMID: 26322928 PMCID: PMC4607767 DOI: 10.1038/nn.4102] [Citation(s) in RCA: 133] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 08/06/2015] [Indexed: 12/30/2022]
Abstract
Aversive experiences can lead to complex behavioral adaptations including increased levels of anxiety and fear generalization. The neuronal mechanisms underlying such maladaptive behavioral changes, however, are poorly understood. Here, using a combination of behavioral, physiological and optogenetic approaches in mouse, we identify a specific subpopulation of central amygdala neurons expressing protein kinase C δ (PKCδ) as key elements of the neuronal circuitry controlling anxiety. Moreover, we show that aversive experiences induce anxiety and fear generalization by regulating the activity of PKCδ(+) neurons via extrasynaptic inhibition mediated by α5 subunit-containing GABAA receptors. Our findings reveal that the neuronal circuits that mediate fear and anxiety overlap at the level of defined subpopulations of central amygdala neurons and demonstrate that persistent changes in the excitability of a single cell type can orchestrate complex behavioral changes.
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Affiliation(s)
- Paolo Botta
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Lynda Demmou
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Yu Kasugai
- Department of Pharmacology, Innsbruck Medical University, Innsbruck, Austria
| | - Milica Markovic
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Chun Xu
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Jonathan P Fadok
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Tingjia Lu
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Michael M Poe
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, USA
| | - Li Xu
- Queensland Brain Institute, University of Queensland, St. Lucia, Queensland, Australia
| | - James M Cook
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, USA
| | - Uwe Rudolph
- Laboratory of Genetic Neuropharmacology, McLean Hospital and Department of Psychiatry, Harvard Medical School, Belmont, Massachusetts, USA
| | - Pankaj Sah
- Queensland Brain Institute, University of Queensland, St. Lucia, Queensland, Australia
| | - Francesco Ferraguti
- Department of Pharmacology, Innsbruck Medical University, Innsbruck, Austria
| | - Andreas Lüthi
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
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20
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Gallos G, Yocum GT, Siviski ME, Yim PD, Fu XW, Poe MM, Cook JM, Harrison N, Perez-Zoghbi J, Emala CW. Selective targeting of the α5-subunit of GABAA receptors relaxes airway smooth muscle and inhibits cellular calcium handling. Am J Physiol Lung Cell Mol Physiol 2015; 308:L931-42. [PMID: 25659897 DOI: 10.1152/ajplung.00107.2014] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 02/05/2015] [Indexed: 12/23/2022] Open
Abstract
The clinical need for novel bronchodilators for the treatment of bronchoconstrictive diseases remains a major medical issue. Modulation of airway smooth muscle (ASM) chloride via GABAA receptor activation to achieve relaxation of precontracted ASM represents a potentially beneficial therapeutic option. Since human ASM GABAA receptors express only the α4- and α5-subunits, there is an opportunity to selectively target ASM GABAA receptors to improve drug efficacy and minimize side effects. Recently, a novel compound (R)-ethyl8-ethynyl-6-(2-fluorophenyl)-4-methyl-4H-benzo[f]imidazo[1,5-a][1,4] diazepine-3-carboxylate (SH-053-2'F-R-CH3) with allosteric selectivity for α5-subunit containing GABAA receptors has become available. We questioned whether this novel GABAA α5-selective ligand relaxes ASM and affects intracellular calcium concentration ([Ca(2+)]i) regulation. Immunohistochemical staining localized the GABAA α5-subunit to human ASM. The selective GABAA α5 ligand SH-053-2'F-R-CH3 relaxes precontracted intact ASM; increases GABA-activated chloride currents in human ASM cells in voltage-clamp electrophysiology studies; and attenuates bradykinin-induced increases in [Ca(2+)]i, store-operated Ca(2+) entry, and methacholine-induced Ca(2+) oscillations in peripheral murine lung slices. In conclusion, selective subunit targeting of endogenous α5-subunit containing GABAA receptors on ASM may represent a novel therapeutic option to treat severe bronchospasm.
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Affiliation(s)
- George Gallos
- Department of Anesthesiology, College of Physicians and Surgeons of Columbia University, New York, New York;
| | - Gene T Yocum
- Department of Anesthesiology, College of Physicians and Surgeons of Columbia University, New York, New York
| | - Matthew E Siviski
- Department of Anesthesiology, College of Physicians and Surgeons of Columbia University, New York, New York
| | - Peter D Yim
- Department of Anesthesiology, College of Physicians and Surgeons of Columbia University, New York, New York
| | - Xiao Wen Fu
- Department of Anesthesiology, College of Physicians and Surgeons of Columbia University, New York, New York
| | - Michael M Poe
- Department of Chemistry, University of Wisconsin, Milwaukee, Wisconsin; and
| | - James M Cook
- Department of Chemistry, University of Wisconsin, Milwaukee, Wisconsin; and
| | - Neil Harrison
- Department of Anesthesiology, College of Physicians and Surgeons of Columbia University, New York, New York
| | - Jose Perez-Zoghbi
- Department of Cell Physiology and Molecular Biophysics; and Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Charles W Emala
- Department of Anesthesiology, College of Physicians and Surgeons of Columbia University, New York, New York
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21
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Sengupta S, Weeraratne SD, Sun H, Phallen J, Rallapalli SK, Teider N, Kosaras B, Amani V, Pierre-Francois J, Tang Y, Nguyen B, Yu F, Schubert S, Balansay B, Mathios D, Lechpammer M, Archer TC, Tran P, Reimer RJ, Cook JM, Lim M, Jensen FE, Pomeroy SL, Cho YJ. α5-GABAA receptors negatively regulate MYC-amplified medulloblastoma growth. Acta Neuropathol 2014; 127:593-603. [PMID: 24196163 DOI: 10.1007/s00401-013-1205-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 10/28/2013] [Indexed: 11/25/2022]
Abstract
Neural tumors often express neurotransmitter receptors as markers of their developmental lineage. Although these receptors have been well characterized in electrophysiological, developmental and pharmacological settings, their importance in the maintenance and progression of brain tumors and, importantly, the effect of their targeting in brain cancers remains obscure. Here, we demonstrate high levels of GABRA5, which encodes the α5-subunit of the GABAA receptor complex, in aggressive MYC-driven, "Group 3" medulloblastomas. We hypothesized that modulation of α5-GABAA receptors alters medulloblastoma cell survival and monitored biological and electrophysiological responses of GABRA5-expressing medulloblastoma cells upon pharmacological targeting of the GABAA receptor. While antagonists, inverse agonists and non-specific positive allosteric modulators had limited effects on medulloblastoma cells, a highly specific and potent α5-GABAA receptor agonist, QHii066, resulted in marked membrane depolarization and a significant decrease in cell survival. This effect was GABRA5 dependent and mediated through the induction of apoptosis as well as accumulation of cells in S and G2 phases of the cell cycle. Chemical genomic profiling of QHii066-treated medulloblastoma cells confirmed inhibition of MYC-related transcriptional activity and revealed an enrichment of HOXA5 target gene expression. siRNA-mediated knockdown of HOXA5 markedly blunted the response of medulloblastoma cells to QHii066. Furthermore, QHii066 sensitized GABRA5 positive medulloblastoma cells to radiation and chemotherapy consistent with the role of HOXA5 in directly regulating p53 expression and inducing apoptosis. Thus, our results provide novel insights into the synthetic lethal nature of α5-GABAA receptor activation in MYC-driven/Group 3 medulloblastomas and propose its targeting as a novel strategy for the management of this highly aggressive tumor.
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Affiliation(s)
- Soma Sengupta
- Department of Neurology, Boston Children's Hospital, Boston, MA, USA
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22
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Martínez-Cué C, Delatour B, Potier MC. Treating enhanced GABAergic inhibition in Down syndrome: use of GABA α5-selective inverse agonists. Neurosci Biobehav Rev 2014; 46 Pt 2:218-27. [PMID: 24412222 DOI: 10.1016/j.neubiorev.2013.12.008] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 11/27/2013] [Accepted: 12/16/2013] [Indexed: 11/27/2022]
Abstract
Excess inhibition in the brain of individuals carrying an extra copy of chromosome 21 could be responsible for cognitive deficits observed throughout their lives. A change in the excitatory/inhibitory balance in adulthood would alter synaptic plasticity, potentially triggering learning and memory deficits. γ-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the mature central nervous system and binds to GABAA receptors, opens a chloride channel, and reduces neuronal excitability. In this review we discuss methods to alleviate neuronal inhibition in a mouse model of Down syndrome, the Ts65Dn mouse, using either an antagonist (pentylenetetrazol) or two different inverse agonists selective for the α5-subunit containing receptor. Both inverse agonists, which reduce inhibitory GABAergic transmission, could rescue learning and memory deficits in Ts65Dn mice. We also discuss safety issues since modulation of the excitatory-inhibitory balance to improve cognition without inducing seizures remains particularly difficult when using GABA antagonists.
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Affiliation(s)
- Carmen Martínez-Cué
- Department of Physiology and Pharmacology, Faculty of Medicine, University of Cantabria, Santander, Spain
| | - Benoît Delatour
- Institut du Cerveau et de Moelle Epinière, CNRS UMR7225, INSERM U1127, UPMC, IHUA-ICM, Hôpital Pitié-Salpêtrière, Paris, France
| | - Marie-Claude Potier
- Institut du Cerveau et de Moelle Epinière, CNRS UMR7225, INSERM U1127, UPMC, IHUA-ICM, Hôpital Pitié-Salpêtrière, Paris, France.
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Khan ZU, Martín-Montañez E, Navarro-Lobato I, Muly EC. Memory deficits in aging and neurological diseases. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 122:1-29. [PMID: 24484696 DOI: 10.1016/b978-0-12-420170-5.00001-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Memory is central to our ability to perform daily life activities and correctly function in society. Improvements in public health and medical treatment for a variety of diseases have resulted in longer life spans; however, age-related memory impairments have been significant sources of morbidity. Loss in memory function is not only associated with aging population but is also a feature of neurodegenerative diseases such as Alzheimer's disease and other psychiatric and neurological disorders. Here, we focus on current understanding of the impact of normal aging on memory and what is known about its mechanisms, and further review pathological mechanisms behind the cause of dementia in Alzheimer's disease. Finally, we discuss schizophrenia and look into abnormalities in circuit function and neurotransmitter systems that contribute to memory impairment in this illness.
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Affiliation(s)
- Zafar U Khan
- Laboratory of Neurobiology at CIMES, University of Málaga, Málaga, Spain; Department of Medicine at Faculty of Medicine, University of Málaga, Málaga, Spain
| | - Elisa Martín-Montañez
- Laboratory of Neurobiology at CIMES, University of Málaga, Málaga, Spain; Department of Pharmacology at Faculty of Medicine, University of Málaga, Málaga, Spain
| | - Irene Navarro-Lobato
- Laboratory of Neurobiology at CIMES, University of Málaga, Málaga, Spain; Department of Medicine at Faculty of Medicine, University of Málaga, Málaga, Spain
| | - E Chris Muly
- Atlanta Department of Veterans Affairs Medical Center, Decatur, Georgia, USA; Department of Psychiatry and Behavioral Sciences, Emory University, Atlanta, Georgia, USA; Division of Neuropharmacology and Neurological Diseases, Yerkes National Primate Research Center, Atlanta, Georgia, USA
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Allosteric modulation of GABA(A) receptor subtypes:effects on visual recognition and visuospatial working memory in rhesus monkeys [corrected]. Neuropsychopharmacology 2013; 38:2315-25. [PMID: 23722241 PMCID: PMC3773684 DOI: 10.1038/npp.2013.137] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 05/21/2013] [Accepted: 05/21/2013] [Indexed: 11/08/2022]
Abstract
Non-selective positive allosteric modulators (PAMs) of GABAA receptors (GABAARs) are known to impair anterograde memory. The role of the various GABAAR subtypes in the memory-impairing effects of non-selective GABAAR PAMs has not been fully elucidated. The current study assessed, in rhesus monkeys, effects of modulation of α1, α2/3, and α5GABAARs on visual recognition and spatial working memory using delayed matching-to-sample (DMTS) and self-ordered spatial search (SOSS) procedures, respectively. The DMTS procedure (n=8) involved selecting a previously presented 'sample' image from a set of multiple images presented after a delay. The SOSS procedure (n=6) involved touching a number of boxes without repeats. The non-selective GABAAR PAM triazolam and the α1GABAA preferential PAMS zolpidem and zaleplon reduced accuracy in both procedures, whereas the α5GABAA preferential PAMs SH-053-2'F-R-CH3 and SH-053-2'F-S-CH3, and the α2/3GABAA preferential PAM TPA023B were without effects on accuracy or trial completion. The low-efficacy α5GABAAR negative allosteric modulator (NAM) PWZ-029 slightly increased only DMTS accuracy, whereas the high-efficacy α5GABAAR NAMs RY-23 and RY-24 did not affect accuracy under either procedure. Finally, the slopes of the accuracy dose-effect curves for triazolam, zolpidem, and zaleplon increased with box number in the SOSS procedure, but were equivalent across DMTS delays. The present results suggest that (1) α1GABAARs, compared with α2/3 and α5GABAARs, are primarily involved in the impairment, by non-selective GABAAR PAMs, of visual recognition and visuospatial working memory in nonhuman primates; and (2) relative cognitive impairment produced by positive modulation of GABAARs increases with number of locations to be remembered, but not with the delay for remembering.
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Guerrini G, Ciciani G. Benzodiazepine receptor ligands: a patent review (2006 – 2012). Expert Opin Ther Pat 2013; 23:843-66. [DOI: 10.1517/13543776.2013.782005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Drexler B, Zinser S, Huang S, Poe MM, Rudolph U, Cook JM, Antkowiak B. Enhancing the function of alpha5-subunit-containing GABAA receptors promotes action potential firing of neocortical neurons during up-states. Eur J Pharmacol 2013; 703:18-24. [PMID: 23380687 DOI: 10.1016/j.ejphar.2013.01.034] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 01/12/2013] [Accepted: 01/16/2013] [Indexed: 11/27/2022]
Abstract
Neocortical neurons mediate the sedative and anticonvulsant properties of benzodiazepines. These agents enhance synaptic inhibition via positive modulation of γ-aminobutyric acid (GABAA) receptors harboring α1-, α2-, α3- or α5-protein subunits. Benzodiazepine-sensitive GABAA receptors containing the α5-subunit are abundant in the neocortex, but their impact in controlling neuronal firing patterns is unknown. Here we studied how the discharge rates of cortical neurons are modified by a positive (SH-053-2'F-R-CH3) and a negative (L 655,708) α5-subunit-preferring allosteric modulator in comparison to diazepam, the classical non-selective benzodiazepine. Drug actions were characterized in slice cultures from wild-type and α5(H105R) knock-in mice by performing extracellular multi-unit-recordings. In knock-in mice, receptors containing the α5 subunit are insensitive to benzodiazepines. The non-selective positive allosteric modulator diazepam decreased the discharge rates of neocortical neurons during episodes of ongoing neuronal activity (up states). In contrast to diazepam, the α5-preferring positive modulator SH-053-2'F-R-CH3 accelerated action potential firing during up states. This promoting action was absent in slices from α5(H105R) mice, confirming that it is mediated by the α5-subunit. Consistent with these observations, the negative α5-selective modulator L 655,708 inhibited up state action potential activity in slices from wild-type mice. The opposing actions of diazepam and SH-053-2'F-R-CH3, which both enhance GABAA receptor function but differ in subtype-selectivity, uncovers contrasting roles of GABAA receptor subtypes in controlling the firing rates of cortical neurons. These findings may have important implications for the design of novel anaesthetic and anticonvulsant benzodiazepines displaying an improved efficacy and fewer side effects.
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Affiliation(s)
- Berthold Drexler
- Experimental Anaesthesiology Section, Department of Anaesthesiology and Intensive Care Medicine, Eberhard-Karls-University, 72072 Tuebingen, Germany.
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Makaron L, Moran CA, Namjoshi O, Rallapalli S, Cook JM, Rowlett JK. Cognition-impairing effects of benzodiazepine-type drugs: role of GABAA receptor subtypes in an executive function task in rhesus monkeys. Pharmacol Biochem Behav 2013; 104:62-8. [PMID: 23290931 DOI: 10.1016/j.pbb.2012.12.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Revised: 11/19/2012] [Accepted: 12/22/2012] [Indexed: 10/27/2022]
Abstract
The present studies evaluated the role of α1 and α5 subunit-containing GABAA receptors (α1GABAA and α5GABAA receptors, respectively) in the ability of benzodiazepine (BZ)-type drugs to alter performance in the cognitive domain of executive function. Five adult female rhesus monkeys (ages of 9-17years old) were trained on the object retrieval with detours (ORD) task of executive function. For the ORD task, the monkeys were required to retrieve food items from a clear box with one open end that was rotated to different positions along with varying placements of food. When the non-selective BZ triazolam and the α1GABAA-preferring agonists zolpidem and zaleplon were evaluated in the ORD task, deficits in performance occurred at doses that did not increase the latency of monkeys to initiate responding and/or increase the percentage of reaches that were incorrect (i.e., reaches in which food was not obtained). Cognition-impairing effects of triazolam and zolpidem in ORD were blocked by the α1GABAA-preferring antagonist, βCCT, whereas the α5GABAA-preferring antagonist XLi-093 blocked the effects of triazolam but not zolpidem. While these findings suggest a role for both α1GABAA and α5GABAA receptor mechanisms, α1GABAA receptor mechanisms appear to be sufficient for impairments in executive function induced by BZ-type drugs.
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Affiliation(s)
- Leah Makaron
- Division of Neuroscience, New England Primate Research Center, Harvard Medical School, Box 9102, 1 Pine Hill Drive, Southborough, MA 01772, USA.
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PWZ-029, an inverse agonist selective for α₅ GABAA receptors, improves object recognition, but not water-maze memory in normal and scopolamine-treated rats. Behav Brain Res 2012; 241:206-13. [PMID: 23261875 DOI: 10.1016/j.bbr.2012.12.016] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 12/07/2012] [Accepted: 12/10/2012] [Indexed: 01/03/2023]
Abstract
Inverse agonism at the benzodiazepine site of α(5) subunit-containing GABA(A) receptors is an attractive approach for the development of putative cognition-enhancing compounds, which are still far from clinical application. Several ligands with binding and/or functional selectivity for α(5) GABA(A) receptors have been synthesized and tested in a few animal models. PWZ-029 is an α(5) GABA(A) selective inverse agonist whose memory enhancing effects were demonstrated in the passive avoidance task in rats and in Pavlovian fear conditioning in mice. In the present study we investigated the effects of PWZ-029 administration in novel object recognition test and Morris water maze, in normal and scopolamine-treated rats. All the three doses of PWZ-029 (2, 5 and 10 mg/kg) improved object recognition after the 24-h delay period, as shown by significant differences between the exploration times of the novel and old object, and the respective discrimination indices. PWZ-029 (2 mg/kg) also successfully reversed the 0.3 mg/kg scopolamine-induced deficit in recognition memory after the 1-h delay. In the Morris water maze test, PWZ-029 (5, 10 and 15 mg/kg) did not significantly influence swim patterns, either during five acquisition days or during the treatment-free probe trial. PWZ-029 (2, 5 and 10 mg/kg) also proved to be ineffective in the reversal of the 1mg/kg scopolamine-induced memory impairment in the water maze. The present mixed results encourage use of a variety of tests and experimental conditions in order to increase the predictability of preclinical testing of selective α(5) GABA(A) inverse agonists.
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Samardžić J, Štrac DŠ, Obradović M, Oprić D, Obradović DI. DMCM, a benzodiazepine site inverse agonist, improves active avoidance and motivation in the rat. Behav Brain Res 2012; 235:195-9. [DOI: 10.1016/j.bbr.2012.07.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 07/19/2012] [Accepted: 07/23/2012] [Indexed: 11/29/2022]
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Sieghart W, Ramerstorfer J, Sarto-Jackson I, Varagic Z, Ernst M. A novel GABA(A) receptor pharmacology: drugs interacting with the α(+) β(-) interface. Br J Pharmacol 2012; 166:476-85. [PMID: 22074382 DOI: 10.1111/j.1476-5381.2011.01779.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
GABA(A) receptors are ligand-gated chloride channels composed of five subunits that can belong to different subunit classes. The existence of 19 different subunits gives rise to a multiplicity of GABA(A) receptor subtypes with distinct subunit composition; regional, cellular and subcellular distribution; and pharmacology. Most of these receptors are composed of two α, two β and one γ2 subunits. GABA(A) receptors are the site of action of a variety of pharmacologically and clinically important drugs, such as benzodiazepines, barbiturates, neuroactive steroids, anaesthetics and convulsants. Whereas GABA acts at the two extracellular β(+) α(-) interfaces of GABA(A) receptors, the allosteric modulatory benzodiazepines interact with the extracellular α(+) γ2(-) interface. In contrast, barbiturates, neuroactive steroids and anaesthetics seem to interact with solvent accessible pockets in the transmembrane domain. Several benzodiazepine site ligands have been identified that selectively interact with GABA(A) receptor subtypes containing α2βγ2, α3βγ2 or α5βγ2 subunits. This indicates that the different α subunit types present in these receptors convey sufficient structural differences to the benzodiazepine binding site to allow specific interaction with certain benzodiazepine site ligands. Recently, a novel drug binding site was identified at the α(+) β(-) interface. This binding site is homologous to the benzodiazepine binding site at the α(+) γ2(-) interface and is thus also strongly influenced by the type of α subunit present in the receptor. Drugs interacting with this binding site cannot directly activate but only allosterically modulate GABA(A) receptors. The possible importance of such drugs addressing a spectrum of receptor subtypes completely different from that of benzodiazepines is discussed.
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Affiliation(s)
- Werner Sieghart
- Department of Biochemistry and Molecular Biology, Center for Brain Research, Medical University Vienna, Vienna, Austria
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Brkic P, Stojiljkovic M, Jovanovic T, Dacic S, Lavrnja I, Savic D, Parabucki A, Bjelobaba I, Rakic L, Pekovic S. Hyperbaric oxygenation improves locomotor ability by enhancing neuroplastic responses after cortical ablation in rats. Brain Inj 2012; 26:1273-84. [PMID: 22571185 DOI: 10.3109/02699052.2012.667593] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE To investigate whether hyperbaric oxygenation (HBO) can improve the recovery of motor functions in rats after suction ablation of the right sensorimotor cortex. METHODS The experimental paradigm implies the following groups: Control animals (C), Control + HBO (CHBO), Sham controls (S), Sham control + HBO (SHBO), Lesion group (L), right sensorimotor cortex was removed by suction, Lesion + HBO (LHBO). Hyperbaric protocol: pressure applied 2.5 atmospheres absolute, for 60 minutes, once a day for 10 days. A beam walking test and grip strength meter were used to evaluate the recovery of motor functions. Expression profiles of growth-associated protein 43 (GAP43) and synaptophysin (SYP) were detected using immunohistochemistry. RESULTS The LHBO group achieved statistically superior scores in the beam walking test compared to the L group. Additionally, the recovery of muscle strength of the affected hindpaw was significantly enhanced after HBO treatment. Hyperbaric oxygenation induced over-expression of GAP43 and SYP in the neurons surrounding the lesion site. CONCLUSIONS Data presented suggest that hyperbaric oxygen therapy can intensify neuroplastic responses by promoting axonal sprouting and synapse remodelling, which contributes to the recovery of locomotor performances in rats. This provides the perspective for implementation of HBO in clinical strategies for treating traumatic brain injuries.
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Affiliation(s)
- Predrag Brkic
- Institute of Medical Physiology 'Richard Burian', School of Medicine, University of Belgrade, Serbia
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The GABA system in anxiety and depression and its therapeutic potential. Neuropharmacology 2012; 62:42-53. [DOI: 10.1016/j.neuropharm.2011.08.040] [Citation(s) in RCA: 348] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Accepted: 08/23/2011] [Indexed: 01/01/2023]
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Möhler H. The rise of a new GABA pharmacology. Neuropharmacology 2011; 60:1042-9. [DOI: 10.1016/j.neuropharm.2010.10.020] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Revised: 10/13/2010] [Accepted: 10/21/2010] [Indexed: 10/18/2022]
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Fischer BD, Atack JR, Platt DM, Reynolds DS, Dawson GR, Rowlett JK. Contribution of GABA(A) receptors containing α3 subunits to the therapeutic-related and side effects of benzodiazepine-type drugs in monkeys. Psychopharmacology (Berl) 2011; 215:311-9. [PMID: 21190016 PMCID: PMC3097109 DOI: 10.1007/s00213-010-2142-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Accepted: 12/07/2010] [Indexed: 11/29/2022]
Abstract
RATIONALE Experimental evidence suggests that the differential behavioral effects of benzodiazepines depend on their relative actions at γ-aminobutyric acid type A (GABA(A)) receptors that contain either an α1, α2, α3, or α5 subunit. OBJECTIVES The present study was aimed at understanding the role of α3 subunit-containing GABA(A) (α3GABA(A)) receptors by examining the behavioral pharmacology of TP003 (4,2'-difluoro-5'-[8-fluoro-7-(1-hydroxy-1-methylethyl)imidazo[1,2-a]pyridine-3-yl]biphenyl-2-carbonitrile), which shows functional selectivity for α3GABA(A) receptors. METHODS First, a conflict procedure was used to assess the anxiolytic-like effects of TP003 and a representative clinically available benzodiazepine. TP003 was also administered before daily periods of sucrose pellet availability to evaluate potential hyperphagic effects. In separate experiments, observable behavioral effects were used to assess the motor and sedative effects of TP003. RESULTS Administration of TP003 produced robust anti-conflict effects without the rate-decreasing effects that were observed with the representative benzodiazepine. Unlike the reported effects of benzodiazepines, TP003 did not enhance palatable food consumption. However, increases in observable sleep-associated posture were induced by TP003, as were decreases in some species-typical behaviors (vocalization, locomotion, and environment-directed behaviors). When evaluated for its ability to induce a procumbent posture, TP003 failed to produce an effect. CONCLUSIONS Based on conflict and observation tests in monkeys, our results suggest that TP003 may have anxiolytic properties but lack ataxic, hyperphagic, and pronounced sedative effects characteristic of classical benzodiazepines. TP003 did induce myorelaxant-like effects and had relatively mild sedative effects. Collectively, these results suggest that α3GABA(A) receptors play an important role in the anxiolytic-like and motor effects of benzodiazepine-type drugs.
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Affiliation(s)
- Bradford D Fischer
- Harvard Medical School, New England Primate Research Center, One Pine Hill Drive, P.O. Box 9102, Southborough, MA 01772-9102, USA.
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Wallace TL, Ballard TM, Pouzet B, Riedel WJ, Wettstein JG. Drug targets for cognitive enhancement in neuropsychiatric disorders. Pharmacol Biochem Behav 2011; 99:130-45. [PMID: 21463652 DOI: 10.1016/j.pbb.2011.03.022] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Revised: 03/18/2011] [Accepted: 03/28/2011] [Indexed: 12/11/2022]
Abstract
The investigation of novel drug targets for treating cognitive impairments associated with neurological and psychiatric disorders remains a primary focus of study in central nervous system (CNS) research. Many promising new therapies are progressing through preclinical and clinical development, and offer the potential of improved treatment options for neurodegenerative diseases such as Alzheimer's disease (AD) as well as other disorders that have not been particularly well treated to date like the cognitive impairments associated with schizophrenia (CIAS). Among targets under investigation, cholinergic receptors have received much attention with several nicotinic agonists (α7 and α4β2) actively in clinical trials for the treatment of AD, CIAS and attention deficit hyperactivity disorder (ADHD). Both glutamatergic and serotonergic (5-HT) agonists and antagonists have profound effects on neurotransmission and improve cognitive function in preclinical experiments with animals; some of these compounds are now in proof-of-concept studies in humans. Several histamine H3 receptor antagonists are in clinical development not only for cognitive enhancement, but also for the treatment of narcolepsy and cognitive deficits due to sleep deprivation because of their expression in brain sleep centers. Compounds that dampen inhibitory tone (e.g., GABA(A) α5 inverse agonists) or elevate excitatory tone (e.g., glycine transporter inhibitors) offer novel approaches for treating diseases such as schizophrenia, AD and Down syndrome. In addition to cell surface receptors, intracellular drug targets such as the phosphodiesterases (PDEs) are known to impact signaling pathways that affect long-term memory formation and working memory. Overall, there is a genuine need to treat cognitive deficits associated with many neuropsychiatric conditions as well as an increasingly aging population.
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MESH Headings
- Animals
- Cognition Disorders/drug therapy
- Cognition Disorders/physiopathology
- Glycine Plasma Membrane Transport Proteins/drug effects
- Glycine Plasma Membrane Transport Proteins/physiology
- Humans
- Learning/drug effects
- Learning/physiology
- Memory/drug effects
- Memory/physiology
- Nootropic Agents/pharmacology
- Phosphodiesterase Inhibitors/pharmacology
- Receptors, Cholinergic/drug effects
- Receptors, Cholinergic/physiology
- Receptors, Dopamine/drug effects
- Receptors, Dopamine/physiology
- Receptors, GABA/drug effects
- Receptors, GABA/physiology
- Receptors, Glutamate/drug effects
- Receptors, Glutamate/physiology
- Receptors, Histamine/drug effects
- Receptors, Histamine/physiology
- Receptors, Serotonin/drug effects
- Receptors, Serotonin/physiology
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Affiliation(s)
- Tanya L Wallace
- Center for Neuroscience, SRI International, Menlo Park, CA, USA
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Savić MM, Kukić JM, Grayer RJ, Milinković MM, Marin PD, Divljaković J, Van Linn M, Cook JM, Petrović SD. Behavioural characterization of four endemic Stachys taxa. Phytother Res 2011; 24:1309-16. [PMID: 20127664 DOI: 10.1002/ptr.3106] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We performed a basic behavioral characterization of methanol extracts of four Balkan endemic Stachys taxa: S. anisochila (SA), S. beckeana (SB), S. plumosa (SP) and S. alpina subsp. dinarica (SAD). The behavioral activity of extracts dosed intraperitoneally in the range 100-400 mg/kg was examined in adult male Wistar rats, in the elevated plus maze, spontaneous locomotor activity, and grip strength tests, mainly predictive of anxiolytic, sedative and myorelaxant actions, respectively. All investigated Stachys extracts lacked anxiolytic or myorelaxant activities, while SB at 400 mg/kg exerted an anxiogenic-like effect. The study with the selective antagonist beta-CCt showed that the sedative effect of SAD was only partially mediated by GABAA receptors containing the alpha1-subunit. While discernible, the behavioral effects of SA and SP were not distinct. In all extracts, chlorogenic acid and verbascoside were identified. In SA, SB, and SAD the flavonoid fraction was constituted of isoscutellarein and hypolaetine glycosides, while in SP chrysoeriol and apigenin glycosides were present. The results reveal the psychotropic potential of four endemic Stachys taxa, of which SAD appeared most promising as a natural sedative.
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Affiliation(s)
- Miroslav M Savić
- Institute of Pharmacology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia.
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Vinkers CH, Mirza NR, Olivier B, Kahn RS. The inhibitory GABA system as a therapeutic target for cognitive symptoms in schizophrenia: investigational agents in the pipeline. Expert Opin Investig Drugs 2011; 19:1217-33. [PMID: 20812877 DOI: 10.1517/13543784.2010.513382] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
IMPORTANCE OF THE FIELD Cognitive impairments associated with schizophrenia include neuropsychological deficits in attention, working memory, learning and executive function. Because these cognitive deficits precede the onset of psychosis, are present in non-affected relatives and constitute the best predictor of functional outcome, they are a cardinal clinical feature in schizophrenia. Currently, no effective treatment for the cognitive symptoms in schizophrenia exists. AREAS COVERED IN THIS REVIEW There is evidence that the inhibitory GABA system is affected in schizophrenia, suggesting that cognitive impairments associated with schizophrenia may be effectively treated by drugs that modulate the GABA(A) receptor. However, classical benzodiazepines produce cognitive impairments and are associated with numerous side effects. The recent development of compounds with selective efficacy for different α subunits at the benzodiazepine site of the GABA(A) receptor has renewed interest for the therapeutic potential of GABAergic drugs. WHAT THE READER WILL GAIN This review summarizes the involvement of the inhibitory GABA system in the cognitive abnormalities of schizophrenia and discusses putative (selective) GABAergic cognition-enhancing drugs for schizophrenia. TAKE HOME MESSAGE If cognitive abnormalities in schizophrenic individuals are the result of GABAergic dysfunction, selectively modulating the GABA system could comprise a promising therapeutic intervention for cognitive symptoms in schizophrenia.
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Affiliation(s)
- Christiaan H Vinkers
- Department of Psychiatry, University Medical Center Utrecht, Rudolf Magnus Institute of Neuroscience, Utrecht, The Netherlands
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Fischer BD, Licata SC, Edwankar RV, Wang ZJ, Huang S, He X, Yu J, Zhou H, Johnson EM, Cook JM, Furtmüller R, Ramerstorfer J, Sieghart W, Roth BL, Majumder S, Rowlett JK. Anxiolytic-like effects of 8-acetylene imidazobenzodiazepines in a rhesus monkey conflict procedure. Neuropharmacology 2010; 59:612-8. [PMID: 20727364 PMCID: PMC2963662 DOI: 10.1016/j.neuropharm.2010.08.011] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Revised: 07/19/2010] [Accepted: 08/10/2010] [Indexed: 11/16/2022]
Abstract
Conflict procedures can be used to study the receptor mechanisms underlying the anxiolytic effects of benzodiazepines and other GABA(A) receptor modulators. In the present study, we first determined the efficacy and binding affinity of the benzodiazepine diazepam and recently synthesized GABA(A) receptor modulators JY-XHe-053, XHe-II-053, HZ-166, SH-053-2'F-S-CH₃ and SH-053-2'F-R-CH₃ at GABA(A) receptors containing α1, α2, α3 and α5 subunits. Results from these studies suggest that each compound displayed lower efficacy at GABA(A) receptors containing α1 subunits and varying degrees of efficacy and affinity at GABA(A) receptors containing α2, α3 and α5 subunits. Next, we assessed their anxiolytic effects using a rhesus monkey conflict procedure in which behavior was maintained under a fixed-ratio schedule of food delivery in the absence (non-suppressed responding) and presence (suppressed responding) of response-contingent electric shock. Relatively non-selective compounds, such as diazepam and JY-XHe-053 produced characteristic increases in rates of suppressed responding at low to intermediate doses and decreased the average rates of non-suppressed responding at higher doses. XHe-II-053 and HZ-166 also produced increases in suppressed responding at low to intermediate doses, but were ineffective at decreasing rates of non-suppressed responding, consistent with their relatively low efficacy at GABA(A) receptors containing α1 and α5 subunits. In contrast, SH-053-2'F-S-CH₃ and SH-053-2'F-R-CH₃ produced only partial increases in suppressed responding and were ineffective on non-suppressed responding, consistent with their profiles as partial agonists at GABA(A) receptors containing α2, α3 and α5 subunits. These behavioral effects suggest that the anxiolytic and rate-reducing effects of GABA(A) receptor positive modulators are dependent on their relative efficacy and affinity at different GABA(A) receptor subtypes.
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Affiliation(s)
- Bradford D Fischer
- Harvard Medical School, New England Primate Research Center, One Pine Hill Drive, P.O. Box 9102, Southborough, Massachusetts 01772-9102, USA.
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Savić MM, Majumder S, Huang S, Edwankar RV, Furtmüller R, Joksimović S, Clayton T, Ramerstorfer J, Milinković MM, Roth BL, Sieghart W, Cook JM. Novel positive allosteric modulators of GABAA receptors: do subtle differences in activity at alpha1 plus alpha5 versus alpha2 plus alpha3 subunits account for dissimilarities in behavioral effects in rats? Prog Neuropsychopharmacol Biol Psychiatry 2010; 34:376-86. [PMID: 20074611 PMCID: PMC2859624 DOI: 10.1016/j.pnpbp.2010.01.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Revised: 01/04/2010] [Accepted: 01/06/2010] [Indexed: 11/18/2022]
Abstract
Over the last years, genetic studies have greatly improved our knowledge on the receptor subtypes mediating various pharmacological effects of positive allosteric modulators at GABA(A) receptors. This stimulated the development of new benzodiazepine (BZ)-like ligands, especially those inactive/low-active at GABA(A) receptors containing the alpha(1) subunit, with the aim of generating more selective drugs. Hereby, the affinity and efficacy of four recently synthesized BZ site ligands: SH-053-2'N, SH-053-S-CH3-2'F, SH-053-R-CH3-2'F and JY-XHe-053 were assessed. They were also studied in behavioral tests of spontaneous locomotor activity, elevated plus maze, and water maze in rats, which are considered predictive of, respectively, the sedative, anxiolytic, and amnesic influence of BZs. The novel ligands had moderately low to low affinity and mild to partial agonistic efficacy at GABA(A) receptors containing the alpha(1) subunit, with variable, but more pronounced efficacy at other BZ-sensitive binding sites. While presumably alpha(1) receptor-mediated sedative effects of GABA(A) modulation were not fully eliminated with any of the ligands tested, only SH-053-2'N and SH-053-S-CH3-2'F, both dosed at 30 mg/kg, exerted anxiolytic effects. The lack of clear anxiolytic-like activity of JY-XHe-053, despite its efficacy at alpha(2)- and alpha(3)-GABA(A) receptors, may have been partly connected with its preferential affinity at alpha(5)-GABA(A) receptors coupled with weak agonist activity at alpha(1)-containing subtypes. The memory impairment in water-maze experiments, generally reported with BZ site agonists, was completely circumvented with all four ligands. The results suggest that a substantial amount of activity at alpha(1) GABA(A) receptors is needed for affecting spatial learning and memory impairments, while much weaker activity at alpha(1)- and alpha(5)-GABA(A) receptors is sufficient for eliciting sedation.
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Affiliation(s)
- Miroslav M Savić
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia.
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Lorenz M, Kabir MS, Cook JM. A two step synthesis of BzR/GABAergic active flavones via a Wacker-related oxidation. Tetrahedron Lett 2010; 51:1095. [PMID: 20161661 DOI: 10.1016/j.tetlet.2009.12.107] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
A general route for the synthesis of biologically important flavones is reported via a two step sequence employing a catalytic Wacker-Cook oxidation4b as the key step.
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Affiliation(s)
- Michael Lorenz
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA
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Preclinical and clinical pharmacology of the GABAA receptor α5 subtype-selective inverse agonist α5IA. Pharmacol Ther 2010; 125:11-26. [DOI: 10.1016/j.pharmthera.2009.09.001] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2009] [Accepted: 09/01/2009] [Indexed: 11/17/2022]
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Discovery of the imidazo[1,5-a][1,2,4]-triazolo[1,5-d][1,4]benzodiazepine scaffold as a novel, potent and selective GABAA α5 inverse agonist series. Bioorg Med Chem Lett 2009; 19:5746-52. [DOI: 10.1016/j.bmcl.2009.07.153] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Revised: 07/30/2009] [Accepted: 07/31/2009] [Indexed: 01/16/2023]
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The differential role of alpha1- and alpha5-containing GABA(A) receptors in mediating diazepam effects on spontaneous locomotor activity and water-maze learning and memory in rats. Int J Neuropsychopharmacol 2009; 12:1179-93. [PMID: 19265570 PMCID: PMC2778330 DOI: 10.1017/s1461145709000108] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The clinical use of benzodiazepines (BZs) is hampered by sedation and cognitive deterioration. Although genetic and pharmacological studies suggest that alpha1- and alpha5-containing GABA(A) receptors mediate and/or modulate these effects, their molecular substrate is not fully elucidated. By the use of two selective ligands: the alpha1-subunit affinity-selective antagonist beta-CCt, and the alpha5-subunit affinity- and efficacy-selective antagonist XLi093, we examined the mechanisms of behavioural effects of diazepam in the tests of spontaneous locomotor activity and water-maze acquisition and recall, the two paradigms indicative of sedative- and cognition-impairing effects of BZs, respectively. The locomotor-activity decreasing propensity of diazepam (significant at 1.5 and 5 mg/kg) was antagonized by beta-CCt (5 and 15 mg/kg), while it tended to be potentiated by XLi093 in doses of 10 mg/kg, and especially 20 mg/kg. Diazepam decreased acquisition and recall in the water maze, with a minimum effective dose of 1.5 mg/kg. Both antagonists reversed the thigmotaxis induced by 2 mg/kg diazepam throughout the test, suggesting that both GABA(A) receptor subtypes participate in BZ effects on the procedural component of the task. Diazepam-induced impairment in the declarative component of the task, as assessed by path efficiency, the latency and distance before finding the platform across acquisition trials, and also by the spatial parameters in the probe trial, was partially prevented by both, 15 mg/kg beta-CCt and 10 mg/kg XLi093. Combining a BZ with beta-CCt results in the near to control level of performance of a cognitive task, without sedation, and may be worth testing on human subjects.
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Atack JR, Maubach KA, Wafford KA, O'Connor D, Rodrigues AD, Evans DC, Tattersall FD, Chambers MS, MacLeod AM, Eng WS, Ryan C, Hostetler E, Sanabria SM, Gibson RE, Krause S, Burns HD, Hargreaves RJ, Agrawal NGB, McKernan RM, Murphy MG, Gingrich K, Dawson GR, Musson DG, Petty KJ. In Vitro and in Vivo Properties of 3-tert-Butyl-7-(5-methylisoxazol-3-yl)-2-(1-methyl-1H-1,2,4-triazol-5-ylmethoxy)-pyrazolo[1,5-d]-[1,2,4]triazine (MRK-016), a GABAA Receptor α5 Subtype-Selective Inverse Agonist. J Pharmacol Exp Ther 2009; 331:470-84. [DOI: 10.1124/jpet.109.157636] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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RO4938581, a novel cognitive enhancer acting at GABAA alpha5 subunit-containing receptors. Psychopharmacology (Berl) 2009; 202:207-23. [PMID: 18936916 DOI: 10.1007/s00213-008-1357-7] [Citation(s) in RCA: 127] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Accepted: 09/26/2008] [Indexed: 12/14/2022]
Abstract
RATIONALE GABAA alpha5 subunit-containing receptors are primarily expressed in the hippocampus and their role in learning and memory has been demonstrated recently by both genetic and pharmacological approaches. OBJECTIVES The objective of the study is to evaluate the cognitive effects of a novel GABAA alpha5 receptor inverse agonist, RO4938581 in rats and monkeys. MATERIALS AND METHODS The in vitro profile was determined using radioligand binding and electrophysiological assays for the GABAA alpha1, alpha2, alpha3, and alpha5 receptors. Long-term potentiation (LTP) was performed in mouse hippocampal slices. Cognitive effects were assessed in rats in the delayed match to position (DMTP) task and the Morris water maze. In monkeys, the object retrieval task was used. Pro-convulsant and anxiogenic potentials were evaluated in mice and rats. In vivo receptor occupancy was determined using [3H]-RO0154513. RESULTS RO4938581 is a potent inverse agonist at the GABAA alpha5 receptor, with both binding and functional selectivity, enhancing hippocampal LTP. RO4938581 reversed scopolamine-induced working memory impairment in the DMTP task (0.3-1 mg/kg p.o.) and diazepam-induced spatial learning impairment (1-10 mg/kg p.o.). RO4938581 improved executive function in monkeys (3-10 mg/kg p.o.). Importantly, RO4938581 showed no anxiogenic and pro-convulsive potential. RO4938581 dose-dependently bound to GABAA alpha5 receptors and approximately 30% receptor occupancy was sufficient to produce enhanced cognition in the rat. CONCLUSIONS The data further support the potential of GABAA alpha5 receptors as a target for cognition-enhancing drugs. The dual binding and functional selectivity offers an ideal profile for cognition-enhancing effects without the unwanted side effects associated with activity at other GABAA receptor subtypes.
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