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Bhagat K, Singh JV, Pagare PP, Kumar N, Sharma A, Kaur G, Kinarivala N, Gandu S, Singh H, Sharma S, Bedi PMS. Rational approaches for the design of various GABA modulators and their clinical progression. Mol Divers 2021; 25:551-601. [PMID: 32170466 PMCID: PMC8422677 DOI: 10.1007/s11030-020-10068-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 02/28/2020] [Indexed: 12/20/2022]
Abstract
GABA (γ-amino butyric acid) is an important inhibitory neurotransmitter in the central nervous system. Attenuation of GABAergic neurotransmission plays an important role in the etiology of several neurological disorders including epilepsy, Alzheimer's disease, Huntington's chorea, migraine, Parkinson's disease, neuropathic pain, and depression. Increase in the GABAergic activity may be achieved through direct agonism at the GABAA receptors, inhibition of enzymatic breakdown of GABA, or by inhibition of the GABA transport proteins (GATs). These functionalities make GABA receptor modulators and GATs attractive drug targets in brain disorders associated with decreased GABA activity. There have been several reports of development of GABA modulators (GABA receptors, GABA transporters, and GABAergic enzyme inhibitors) in the past decade. Therefore, the focus of the present review is to provide an overview on various design strategies and synthetic approaches toward developing GABA modulators. Furthermore, mechanistic insights, structure-activity relationships, and molecular modeling inputs for the biologically active derivatives have also been discussed. Summary of the advances made over the past few years in the clinical translation and development of GABA receptor modulators is also provided. This compilation will be of great interest to the researchers working in the field of neuroscience. From the light of detailed literature, it can be concluded that numerous molecules have displayed significant results and their promising potential, clearly placing them ahead as potential future drug candidates.
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Affiliation(s)
- Kavita Bhagat
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, PB, 143005, India
| | - Jatinder V Singh
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, PB, 143005, India
| | - Piyusha P Pagare
- Department of Medicinal Chemistry, School of Pharmacy and Institute for Structural Biology, Drug Discovery and Development, Virginia Commonwealth University, Richmond, VA, 23219, USA
| | - Nitish Kumar
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, PB, 143005, India
| | - Anchal Sharma
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, PB, 143005, India
| | - Gurinder Kaur
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, PB, 143005, India
| | - Nihar Kinarivala
- Program in Chemical Biology, Sloan Kettering Institute, New York, NY, 10065, USA
| | - Srinivasa Gandu
- Department of Cell Biology and Neuroscience, Cell and Development Biology Graduate Program, The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Harbinder Singh
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, PB, 143005, India.
| | - Sahil Sharma
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, PB, 143005, India.
- Program in Chemical Biology, Sloan Kettering Institute, New York, NY, 10065, USA.
| | - Preet Mohinder S Bedi
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, PB, 143005, India.
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Solomon VR, Tallapragada VJ, Chebib M, Johnston G, Hanrahan JR. GABA allosteric modulators: An overview of recent developments in non-benzodiazepine modulators. Eur J Med Chem 2019; 171:434-461. [DOI: 10.1016/j.ejmech.2019.03.043] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Revised: 02/17/2019] [Accepted: 03/17/2019] [Indexed: 01/13/2023]
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3
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Neighboring Group Participation in 12,20-Dioxopregnanes. Nat Prod Commun 2019. [DOI: 10.1177/1934578x0700201108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
12,20-Dioxo-5α-pregnan-3β-yl acetate, obtained from hecogenin, was treated with NaH in DMSO to yield the bridged cyclopropano ketone, 3β-hydroxy-12α,21-cyclo-12β,21-methano-5α,17α-pregnan-20-one. In tert-BuOH the reaction leads to 3β-hydroxy-12,21-cyclo-5α-pregn-12,21-en-20-one. Experimental data prove that the new methylene group of the cyclopropane ring came from DMSO.
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Clarified Açaí ( Euterpe oleracea) Juice as an Anticonvulsant Agent : In Vitro Mechanistic Study of GABAergic Targets. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2018; 2018:2678089. [PMID: 29743978 PMCID: PMC5883935 DOI: 10.1155/2018/2678089] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 02/07/2018] [Indexed: 11/18/2022]
Abstract
Seizures affect about 50 million people around the world. Approximately 30% of seizures are refractory to the current pharmacological arsenal, so, the pursuit of new therapeutic alternatives is essential. Clarified Euterpe oleracea (EO) juice showed anticonvulsant properties similar to diazepam in an in vivo model with pentylenetetrazol, a GABAA receptor blocker. This study investigated the effects of EO on the main GABAergic targets for anticonvulsant drugs, analyzing the effect on the GABA receptor's benzodiazepine and picrotoxinin binding sites and the GABA uptake. Primary cultures of cortical neurons and astrocytes were treated with EO (0–25%) for up to 90 min. [3H]Flunitrazepam and [3H]TBOB binding, [3H]GABA uptake, cell viability, and morphology were assayed. Nonlethal concentrations of EO increased agonist binding and decreased antagonist binding in cortical neurons. Low concentrations significantly inhibited GABA uptake, especially in astrocytes, suggesting an accumulation of endogenous GABA in the synaptic cleft. The results demonstrate, for the first time, that EO can improve GABAergic neurotransmission via interactions with GABAA receptor and modulation of GABA uptake. Understanding these molecular mechanisms will help in the treatment of seizures and epilepsy, especially in developing countries where geographic isolation and low purchasing power are the main barriers to access to adequate treatment.
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Effect of synthetic steroids on GABAA receptor binding in rat brain. Neuroscience 2015; 290:138-46. [DOI: 10.1016/j.neuroscience.2014.12.082] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 11/20/2014] [Accepted: 12/17/2014] [Indexed: 11/24/2022]
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6
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GABAergic pharmacological activity of propofol related compounds as possible enhancers of general anesthetics and interaction with membranes. Cell Biochem Biophys 2014; 67:515-25. [PMID: 23456454 DOI: 10.1007/s12013-013-9537-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Phenol compounds, such as propofol and thymol, have been shown to act on the GABAA receptor through interaction with specific sites of this receptor. In addition, considering the high lipophilicity of phenols, it is possible that their pharmacological activity may also be the result of the interaction of phenol molecules with the surrounding lipid molecules, modulating the supramolecular organization of the receptor environment. Thus, in the present study, we study the pharmacological activity of some propofol- and thymol-related phenols on the native GABAA receptor using primary cultures of cortical neurons and investigate the effects of these compounds on the micro viscosity of artificial membranes by means of fluorescence anisotropy. The phenol compounds analyzed in this article are carvacrol, chlorothymol, and eugenol. All compounds were able to enhance the binding of [(3)H]flunitrazepam with EC50 values in the micromolar range and to increase the GABA-evoked Cl(-) influx in a concentration-dependent manner, both effects being inhibited by the competitive GABAA antagonist bicuculline. These results strongly suggest that the phenols studied are positive allosteric modulators of this receptor. Chlorothymol showed a bell-type effect, reducing its positive effect at concentrations >100 μM. The concentrations necessary to induce positive allosteric modulation of GABAA receptor were not cytotoxic. Although all compounds were able to decrease the micro viscosity of artificial membranes, chlorothymol displayed a larger effect which could explain its effects on [(3)H]flunitrazepam binding and on cell viability at high concentrations. Finally, it is suggested that these compounds may exert depressant activity on the central nervous system and potentiate the effects of general anesthetics.
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Sánchez-Borzone M, Delgado-Marín L, García DA. Inhibitory Effects of Carvone Isomers on the GABAA
Receptor in Primary Cultures of Rat Cortical Neurons. Chirality 2014; 26:368-72. [DOI: 10.1002/chir.22328] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 03/12/2014] [Accepted: 03/15/2014] [Indexed: 12/26/2022]
Affiliation(s)
- Mariela Sánchez-Borzone
- Instituto de Investigaciones Biológicas y Tecnológicas (IIBYT); CONICET-Universidad Nacional de Córdoba; Córdoba Argentina
| | - Leticia Delgado-Marín
- Instituto de Investigaciones Biológicas y Tecnológicas (IIBYT); CONICET-Universidad Nacional de Córdoba; Córdoba Argentina
| | - Daniel A. García
- Instituto de Investigaciones Biológicas y Tecnológicas (IIBYT); CONICET-Universidad Nacional de Córdoba; Córdoba Argentina
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9
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Rey M, Kruse MS, Alvarez LD, Ghini AA, Veleiro AS, Burton G, Coirini H. Neuroprotective action of synthetic steroids with oxygen bridge. Activity on GABAA receptor. Exp Neurol 2013; 249:49-58. [DOI: 10.1016/j.expneurol.2013.07.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 07/24/2013] [Accepted: 07/27/2013] [Indexed: 11/16/2022]
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Slavíková B, Bujons J, Matyáš L, Vidal M, Babot Z, Krištofíková Z, Suñol C, Kasal A. Allopregnanolone and pregnanolone analogues modified in the C ring: synthesis and activity. J Med Chem 2013; 56:2323-36. [PMID: 23421641 DOI: 10.1021/jm3016365] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
(25R)-3β-Hydroxy-5α-spirostan-12-one (hecogenin) and 11α-hydroxypregn-4-ene-3,20-dione (11α-hydroxyprogesterone) were used as starting materials for the synthesis of a series of 11- and 12-substituted derivatives of 5ξ-pregnanolone (3α-hydroxy-5α-pregnan-20-one and 3α-hydroxy-5β-pregnan-20-one), the principal neurosteroid acting via γ-aminobutyric acid (GABA). These analogues were designed to study the structural requirements of the corresponding GABAA receptor. Their biological activity was measured by in vitro test with [(3)H]flunitrazepam as radioligand in which allopregnanolone and its active analogues stimulated the binding to the GABAA receptor. Analysis of the SAR data suggests dependence of the flunitrazepam binding activity on the hydrophobic-hydrophilic balance of the groups at the C-ring edge rather than on specific interactions between them and the receptor.
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Affiliation(s)
- Barbora Slavíková
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 166 10 Prague 6, Czech Republic
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Briz V, Parkash J, Sánchez-Redondo S, Prevot V, Suñol C. Allopregnanolone prevents dieldrin-induced NMDA receptor internalization and neurotoxicity by preserving GABA(A) receptor function. Endocrinology 2012; 153:847-60. [PMID: 22166974 DOI: 10.1210/en.2011-1333] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Dieldrin is an endocrine disruptor that accumulates in mammalian adipose tissue and brain. It induces convulsions due to its antagonism of the γ-aminobutyric acid A receptor (GABA(A)R). We have previously reported that long-term exposure to dieldrin causes the internalization of the N-methyl-D-aspartate receptor (NMDAR) as a result of persistent GABA(A)R inhibition. Because the neurosteroids 17β-estradiol (E2) and allopregnanolone are known to modulate the function and trafficking of GABA(A)R and NMDAR, we examined the effects of E2 and allopregnanolone on dieldrin-induced GABA(A)R inhibition, NMDAR internalization, and neuronal death in cortical neurons. We found that 1 nM E2 increased the membrane expression of NR1/NR2B receptors and postsynaptic density 95 but did not induce their physical association. In contrast, 10 nM E2 had no effect on these proteins but reduced NR2A membrane expression. We also found that exposure to 60 nM dieldrin for 6 d in vitro caused the internalization of NR1 and NR2B but not NR2A. Treatment with either 1 nM E2 or 10 μM allopregnanolone prevented the dieldrin-induced reduction in membrane levels of the NR1/NR2B receptors. Furthermore, prolonged exposure to 200 nM dieldrin down-regulated the expression of NR2A; this was inhibited only by allopregnanolone. Although both hormones restored NMDAR function, as measured by the NMDA-induced rise in intracellular calcium, allopregnanolone (but not E2) reversed the inhibition of GABA(A)R and neuronal death caused by prolonged exposure to dieldrin. Our results indicate that allopregnanolone protects cortical neurons against the neurotoxicity caused by long-term exposure to dieldrin by maintaining GABA(A)R and NMDAR functionality.
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Affiliation(s)
- Víctor Briz
- Department of Neurochemistry and Neuropharmacology, Consejo Superior de Investigaciones Científicas-Institut d'Investigacions Biomèdiques August Pi i Sunyer (IIBB-CSIC-IDIBAPS), Centro de Investigación Biomédica en Red Epidemiology and Public Health (CIBERESP), E-08036, Barcelona, Spain
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Uyanik C, Hanson JR. The Chemistry of B-Norsteroidal 6-Ketones and their Relatives. JOURNAL OF CHEMICAL RESEARCH 2011. [DOI: 10.3184/174751911x13146264913491] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The preparation and reactions of B-norsteroidal 6-ketones and their relatives are reviewed in the context of the stability of the A/B and B/C ring junctions and the stereochemistry of the addition reactions to the carbonyl group. This review is a sequel to a previous article on the reactions of B-norsteroidal 4- and 5-enes.
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Affiliation(s)
- Cavit Uyanik
- Department of Chemistry, University of Kocaeli, Umuttepe, Izmit 41380, Kocaeli, Turkey
| | - James R. Hanson
- Department of Chemistry, University of Sussex, Brighton, Sussex BN1 9QJ, UK
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13
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Zhang Z, Wang L, Bian X, Sun Q, Xu H, Wang C. First Synthesis of a C-Homosteroid from Pregn-4-ene-3,11,20-trione. Helv Chim Acta 2011. [DOI: 10.1002/hlca.201000132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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14
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GABAA Receptor Binding and Ion Channel Function in Primary Neuronal Cultures for Neuropharmacology/Neurotoxicity Testing. NEUROMETHODS 2011. [DOI: 10.1007/978-1-61779-077-5_25] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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15
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GABAA receptor and cell membrane potential as functional endpoints in cultured neurons to evaluate chemicals for human acute toxicity. Neurotoxicol Teratol 2010; 32:52-61. [DOI: 10.1016/j.ntt.2009.01.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Revised: 01/16/2009] [Accepted: 01/20/2009] [Indexed: 11/22/2022]
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16
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Abstract
Aspects of the stereochemistry of addition reactions to B-norsteroidal 4- and 5-alkenes are compared to the corresponding reactions in normal 6:6 A/B series.
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Affiliation(s)
- Cavit Uyanik
- Department of Chemistry, University of Kocaeli, Umuttepe, Izmit 41380, Kocaeli, Turkey
| | - James R. Hanson
- Department of Chemistry, University of Sussex, Brighton, Sussex BN1 9QJ, UK
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Slavíková B, Krištofíková Z, Chodounská H, Buděšínský M, Durán FJ, Veleiro AS, Burton G, Kasal A. Allopregnanolone (3α-Hydroxy-5α-pregnan-20-one) Derivatives with a Polar Chain in Position 16α: Synthesis and Activity. J Med Chem 2009; 52:2119-25. [DOI: 10.1021/jm801454a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Barbora Slavíková
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, CZ16610 Prague 6, Czech Republic, Prague Psychiatric Centre, Ústavní 91, CZ18103 Prague, Czech Republic, and Departamento de Química Orgánica and UMYMFOR (CONICET-UBA), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Zdena Krištofíková
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, CZ16610 Prague 6, Czech Republic, Prague Psychiatric Centre, Ústavní 91, CZ18103 Prague, Czech Republic, and Departamento de Química Orgánica and UMYMFOR (CONICET-UBA), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Hana Chodounská
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, CZ16610 Prague 6, Czech Republic, Prague Psychiatric Centre, Ústavní 91, CZ18103 Prague, Czech Republic, and Departamento de Química Orgánica and UMYMFOR (CONICET-UBA), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Miloš Buděšínský
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, CZ16610 Prague 6, Czech Republic, Prague Psychiatric Centre, Ústavní 91, CZ18103 Prague, Czech Republic, and Departamento de Química Orgánica and UMYMFOR (CONICET-UBA), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Fernando J. Durán
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, CZ16610 Prague 6, Czech Republic, Prague Psychiatric Centre, Ústavní 91, CZ18103 Prague, Czech Republic, and Departamento de Química Orgánica and UMYMFOR (CONICET-UBA), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Adriana S. Veleiro
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, CZ16610 Prague 6, Czech Republic, Prague Psychiatric Centre, Ústavní 91, CZ18103 Prague, Czech Republic, and Departamento de Química Orgánica and UMYMFOR (CONICET-UBA), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Gerardo Burton
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, CZ16610 Prague 6, Czech Republic, Prague Psychiatric Centre, Ústavní 91, CZ18103 Prague, Czech Republic, and Departamento de Química Orgánica and UMYMFOR (CONICET-UBA), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Alexander Kasal
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, CZ16610 Prague 6, Czech Republic, Prague Psychiatric Centre, Ústavní 91, CZ18103 Prague, Czech Republic, and Departamento de Química Orgánica and UMYMFOR (CONICET-UBA), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
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García DA, Vendrell I, Galofré M, Suñol C. GABA released from cultured cortical neurons influences the modulation of t-[35S]butylbicyclophosphorothionate binding at the GABAA receptor. Eur J Pharmacol 2008; 600:26-31. [DOI: 10.1016/j.ejphar.2008.10.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2008] [Revised: 09/29/2008] [Accepted: 10/06/2008] [Indexed: 11/28/2022]
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Scaglione JB, Jastrzebska I, Krishnan K, Li P, Akk G, Manion BD, Benz A, Taylor A, Rath NP, Evers AS, Zorumski CF, Mennerick S, Covey DF. Neurosteroid analogues. 14. Alternative ring system scaffolds: GABA modulatory and anesthetic actions of cyclopenta[b]phenanthrenes and cyclopenta[b]anthracenes. J Med Chem 2008; 51:1309-18. [PMID: 18275132 DOI: 10.1021/jm701128r] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Although the structural features of binding sites for neuroactive steroids on gamma-aminobutryic acid type A (GABA A) receptors are still largely unknown, structure-activity studies have established a pharmacophore for potent enhancement of GABA A receptor function by neuroactive steroids. This pharmacophore emphasizes the importance of the position and stereochemistry of hydrogen-bonding groups on the steroid. However, the importance of the steroid ring system in mediating hydrophobic interactions with the GABA A receptor is unclear. We have taken the cyclopenta[ b]phenanthrene (tetracyclic compounds with a nonlinear ring system different from that of steroids) and cyclopenta[ b]anthracene (tetracyclic molecules with a linear 6-6-6-5 carbocyclic ring system) ring systems and properly substituted them to satisfy the pharmacophore requirements of the critical hydrogen-bond donor and acceptor groups found in neuroactive steroids. We have found these cyclopenta[ b]phenanthrene and cyclopenta[ b]anthracene analogues to have potent activity at the GABA A receptor, rivaling that of the most potent steroid modulators. Single-channel analysis of electrophysiological data indicates that similarly substituted analogues in the different ring systems affect the kinetic components of macroscopic currents in different ways. Mutations to the hydrogen bonding amino acids at the putative steroid binding site (alpha1Q241L mutation and alpha1N407A/Y410F double mutation) produce similar effects on macroscopic current amplitude by the different ring system analogues suggesting that the different kinetic effects are explained by the precise interactions of each analogue with the same binding site(s).
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Affiliation(s)
- Jamie B Scaglione
- Department of Molecular Biology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Hosie AM, Wilkins ME, Smart TG. Neurosteroid binding sites on GABA(A) receptors. Pharmacol Ther 2007; 116:7-19. [PMID: 17560657 DOI: 10.1016/j.pharmthera.2007.03.011] [Citation(s) in RCA: 165] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2007] [Accepted: 03/29/2007] [Indexed: 10/23/2022]
Abstract
Controlling neuronal excitability is vitally important for maintaining a healthy central nervous system (CNS) and this relies on the activity of type A gamma-aminobutyric acid (GABA(A)) neurotransmitter receptors. Given this role, it is therefore important to understand how these receptors are regulated by endogenous modulators in the brain and determine where they bind to the receptor. One of the most potent groups of modulators is the neurosteroids which regulate the activity of synaptic and extrasynaptic GABA(A) receptors. This level of regulation is thought to be physiologically important and its dysfunction may be relevant to numerous neurological conditions. The aim of this review is to summarise those studies that over the last 20 years have focussed upon finding the binding sites for neurosteroids on GABA(A) receptors. We consider the nature of steroid binding sites in other proteins where this has been determined at atomic resolution and how their generic features were mapped onto GABA(A) receptors to help locate 2 putative steroid binding sites. Altogether, the findings strongly suggest that neurosteroids do bind to discrete sites on the GABA(A) receptor and that these are located within the transmembrane domains of alpha and beta receptor subunits. The implications for neurosteroid binding to other inhibitory receptors such as glycine and GABA(C) receptors are also considered. Identifying neurosteroid binding sites may enable the precise pathophysiological role(s) of neurosteroids in the CNS to be established for the first time, as well as providing opportunities for the design of novel drug entities.
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Affiliation(s)
- Alastair M Hosie
- University College London, Department of Pharmacology, Gower Street, London, WC1E 6BT
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