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Two Distinct Populations of α1α6-Containing GABAA-Receptors in Rat Cerebellum
GABAA receptors are pentameric GABA-gated chloride channels. The existence of 19 different subunits (six α, three β, three γ, δ, ε, θ, π, and three ρ) in mammalian systems gives rise to an enormous theoretical diversity of GABAA receptor subtypes with distinct subunit composition and unique pharmaco...
Autores principales: | , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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Frontiers Media S.A.
2020
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7573486/ https://www.ncbi.nlm.nih.gov/pubmed/33123001 http://dx.doi.org/10.3389/fnsyn.2020.591129 |
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author | Scholze, Petra Pökl, Michael Längle, Severin Steudle, Friederike Fabjan, Jure Ernst, Margot |
author_facet | Scholze, Petra Pökl, Michael Längle, Severin Steudle, Friederike Fabjan, Jure Ernst, Margot |
author_sort | Scholze, Petra |
collection | PubMed |
description | GABAA receptors are pentameric GABA-gated chloride channels. The existence of 19 different subunits (six α, three β, three γ, δ, ε, θ, π, and three ρ) in mammalian systems gives rise to an enormous theoretical diversity of GABAA receptor subtypes with distinct subunit composition and unique pharmacological properties. These receptors are already now the drug targets of several clinically used compounds, such as benzodiazepines, anesthetics, and many more. There is a constant quest to identify novel molecules and possible future drug targets: Currently, α6-containing GABAA receptors are being discussed in the context of treating sensorimotor gating deficits in neuropsychiatric disorders, such as tic disorders and schizophrenia. Therefore, we aim to learn more about α6-containing GABAA receptors. They are mostly expressed in the cerebellar granule cell layer, where they form the following subtypes: α6βxγ2, α1α6βxγ2, α6βxδ, and α1α6βxδ. In former studies, α1α6βxγ2-containing GABAA receptors were considered a single receptor population. In the current study, we investigate the possibility, that this population can consist of two subgroups with alternative arrangements depending if α1 neighbors γ2 (forming a “diazepam-sensitive” receptor), or if α6 neighbors γ2 (forming a “diazepam-insensitive” receptor) and aimed to prove the existence of both subtypes in native tissue. We performed immunoprecipitation experiments on rat cerebellar lysates using α1- or α6 subunit-specific antibodies followed by radioligand binding assays with either (3)H-flunitrazepam or (3)H-Ro 15-4513. Indeed, we were able to prove the existence of two distinct populations of α1α6-containing GABAA-receptors and could quantify the different receptor populations: α1βxγ2 receptors constitute approximately 60% of all γ2-containing receptors in the rat cerebellum, α6βxγ2 about 20%, and both isoforms of α1α6βxγ2 9–15% each. The simple classification of GABAA-receptors into αx-containing subtypes seems not to reflect the complexity of nature; those receptors are more diverse than previously thought. |
format | Online Article Text |
id | pubmed-7573486 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2020 |
publisher | Frontiers Media S.A. |
record_format | MEDLINE/PubMed |
spelling | pubmed-75734862020-10-28 Two Distinct Populations of α1α6-Containing GABAA-Receptors in Rat Cerebellum Scholze, Petra Pökl, Michael Längle, Severin Steudle, Friederike Fabjan, Jure Ernst, Margot Front Synaptic Neurosci Neuroscience GABAA receptors are pentameric GABA-gated chloride channels. The existence of 19 different subunits (six α, three β, three γ, δ, ε, θ, π, and three ρ) in mammalian systems gives rise to an enormous theoretical diversity of GABAA receptor subtypes with distinct subunit composition and unique pharmacological properties. These receptors are already now the drug targets of several clinically used compounds, such as benzodiazepines, anesthetics, and many more. There is a constant quest to identify novel molecules and possible future drug targets: Currently, α6-containing GABAA receptors are being discussed in the context of treating sensorimotor gating deficits in neuropsychiatric disorders, such as tic disorders and schizophrenia. Therefore, we aim to learn more about α6-containing GABAA receptors. They are mostly expressed in the cerebellar granule cell layer, where they form the following subtypes: α6βxγ2, α1α6βxγ2, α6βxδ, and α1α6βxδ. In former studies, α1α6βxγ2-containing GABAA receptors were considered a single receptor population. In the current study, we investigate the possibility, that this population can consist of two subgroups with alternative arrangements depending if α1 neighbors γ2 (forming a “diazepam-sensitive” receptor), or if α6 neighbors γ2 (forming a “diazepam-insensitive” receptor) and aimed to prove the existence of both subtypes in native tissue. We performed immunoprecipitation experiments on rat cerebellar lysates using α1- or α6 subunit-specific antibodies followed by radioligand binding assays with either (3)H-flunitrazepam or (3)H-Ro 15-4513. Indeed, we were able to prove the existence of two distinct populations of α1α6-containing GABAA-receptors and could quantify the different receptor populations: α1βxγ2 receptors constitute approximately 60% of all γ2-containing receptors in the rat cerebellum, α6βxγ2 about 20%, and both isoforms of α1α6βxγ2 9–15% each. The simple classification of GABAA-receptors into αx-containing subtypes seems not to reflect the complexity of nature; those receptors are more diverse than previously thought. Frontiers Media S.A. 2020-10-06 /pmc/articles/PMC7573486/ /pubmed/33123001 http://dx.doi.org/10.3389/fnsyn.2020.591129 Text en Copyright © 2020 Scholze, Pökl, Längle, Steudle, Fabjan and Ernst. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. |
spellingShingle | Neuroscience Scholze, Petra Pökl, Michael Längle, Severin Steudle, Friederike Fabjan, Jure Ernst, Margot Two Distinct Populations of α1α6-Containing GABAA-Receptors in Rat Cerebellum |
title | Two Distinct Populations of α1α6-Containing GABAA-Receptors in Rat Cerebellum |
title_full | Two Distinct Populations of α1α6-Containing GABAA-Receptors in Rat Cerebellum |
title_fullStr | Two Distinct Populations of α1α6-Containing GABAA-Receptors in Rat Cerebellum |
title_full_unstemmed | Two Distinct Populations of α1α6-Containing GABAA-Receptors in Rat Cerebellum |
title_short | Two Distinct Populations of α1α6-Containing GABAA-Receptors in Rat Cerebellum |
title_sort | two distinct populations of α1α6-containing gabaa-receptors in rat cerebellum |
topic | Neuroscience |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7573486/ https://www.ncbi.nlm.nih.gov/pubmed/33123001 http://dx.doi.org/10.3389/fnsyn.2020.591129 |
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