Altering the relative abundance of GABA A receptor subunits changes GABA- and ethanol-responses in xenopus oocytes

Joyce Hurley, Carrie J. Ballard, Howard Edenberg

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Background: Variations in GABRA2 and GABRG3, genes encoding the α2 and γ3 subunits of the pentameric GABA A receptor, are associated with the risk of developing alcoholism in adults, conduct disorder at younger ages, and with differences in electroencephalographic power in the β frequency range. The SNPs associated with alcoholism did not alter the coding of these genes, and extensive DNA sequencing of GABRA2 did not find coding changes in the high-risk haplotypes. Therefore, we hypothesize that the associations arise from differences in gene expression. Methods: Here we report studies in Xenopus oocytes to examine the functional effects of altering the relative abundance of these 2 receptor subunits on GABA current and response to ethanol, as a model of potential effects of regulatory differences. Results: When human α2β2γ3 subunits are co-expressed, increasing the amount of the α2 subunit mRNA increased GABA current; in contrast, increasing the amount of the γ3 subunit decreased GABA currents. Acute ethanol treatment of oocytes injected with a 1:1:1 or 2:2:1 ratio of α2:β2:γ3 subunit mRNAs resulted in significant potentiation of GABA currents, whereas ethanol inhibited GABA currents in cells injected with a 6:2:1 ratio. Overnight treatment with ethanol significantly reduced GABA currents in a manner dependent on the ratio of subunits. Conclusions: These studies demonstrate that changes in relative expression of GABA A receptor subunits alter the response of the resulting channels to GABA and to ethanol.

Original languageEnglish
Pages (from-to)1089-1096
Number of pages8
JournalAlcoholism: Clinical and Experimental Research
Volume33
Issue number6
DOIs
StatePublished - Jun 2009

Fingerprint

GABA-A Receptors
Xenopus
gamma-Aminobutyric Acid
Oocytes
Ethanol
Alcoholism
Conduct Disorder
Messenger RNA
Gene encoding
DNA Sequence Analysis
Gene expression
Haplotypes
Genes
Single Nucleotide Polymorphism
Gene Expression
DNA

Keywords

  • Ethanol
  • GABA receptors
  • Voltage clamp

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Psychiatry and Mental health
  • Toxicology

Cite this

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title = "Altering the relative abundance of GABA A receptor subunits changes GABA- and ethanol-responses in xenopus oocytes",
abstract = "Background: Variations in GABRA2 and GABRG3, genes encoding the α2 and γ3 subunits of the pentameric GABA A receptor, are associated with the risk of developing alcoholism in adults, conduct disorder at younger ages, and with differences in electroencephalographic power in the β frequency range. The SNPs associated with alcoholism did not alter the coding of these genes, and extensive DNA sequencing of GABRA2 did not find coding changes in the high-risk haplotypes. Therefore, we hypothesize that the associations arise from differences in gene expression. Methods: Here we report studies in Xenopus oocytes to examine the functional effects of altering the relative abundance of these 2 receptor subunits on GABA current and response to ethanol, as a model of potential effects of regulatory differences. Results: When human α2β2γ3 subunits are co-expressed, increasing the amount of the α2 subunit mRNA increased GABA current; in contrast, increasing the amount of the γ3 subunit decreased GABA currents. Acute ethanol treatment of oocytes injected with a 1:1:1 or 2:2:1 ratio of α2:β2:γ3 subunit mRNAs resulted in significant potentiation of GABA currents, whereas ethanol inhibited GABA currents in cells injected with a 6:2:1 ratio. Overnight treatment with ethanol significantly reduced GABA currents in a manner dependent on the ratio of subunits. Conclusions: These studies demonstrate that changes in relative expression of GABA A receptor subunits alter the response of the resulting channels to GABA and to ethanol.",
keywords = "Ethanol, GABA receptors, Voltage clamp",
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AU - Edenberg, Howard

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N2 - Background: Variations in GABRA2 and GABRG3, genes encoding the α2 and γ3 subunits of the pentameric GABA A receptor, are associated with the risk of developing alcoholism in adults, conduct disorder at younger ages, and with differences in electroencephalographic power in the β frequency range. The SNPs associated with alcoholism did not alter the coding of these genes, and extensive DNA sequencing of GABRA2 did not find coding changes in the high-risk haplotypes. Therefore, we hypothesize that the associations arise from differences in gene expression. Methods: Here we report studies in Xenopus oocytes to examine the functional effects of altering the relative abundance of these 2 receptor subunits on GABA current and response to ethanol, as a model of potential effects of regulatory differences. Results: When human α2β2γ3 subunits are co-expressed, increasing the amount of the α2 subunit mRNA increased GABA current; in contrast, increasing the amount of the γ3 subunit decreased GABA currents. Acute ethanol treatment of oocytes injected with a 1:1:1 or 2:2:1 ratio of α2:β2:γ3 subunit mRNAs resulted in significant potentiation of GABA currents, whereas ethanol inhibited GABA currents in cells injected with a 6:2:1 ratio. Overnight treatment with ethanol significantly reduced GABA currents in a manner dependent on the ratio of subunits. Conclusions: These studies demonstrate that changes in relative expression of GABA A receptor subunits alter the response of the resulting channels to GABA and to ethanol.

AB - Background: Variations in GABRA2 and GABRG3, genes encoding the α2 and γ3 subunits of the pentameric GABA A receptor, are associated with the risk of developing alcoholism in adults, conduct disorder at younger ages, and with differences in electroencephalographic power in the β frequency range. The SNPs associated with alcoholism did not alter the coding of these genes, and extensive DNA sequencing of GABRA2 did not find coding changes in the high-risk haplotypes. Therefore, we hypothesize that the associations arise from differences in gene expression. Methods: Here we report studies in Xenopus oocytes to examine the functional effects of altering the relative abundance of these 2 receptor subunits on GABA current and response to ethanol, as a model of potential effects of regulatory differences. Results: When human α2β2γ3 subunits are co-expressed, increasing the amount of the α2 subunit mRNA increased GABA current; in contrast, increasing the amount of the γ3 subunit decreased GABA currents. Acute ethanol treatment of oocytes injected with a 1:1:1 or 2:2:1 ratio of α2:β2:γ3 subunit mRNAs resulted in significant potentiation of GABA currents, whereas ethanol inhibited GABA currents in cells injected with a 6:2:1 ratio. Overnight treatment with ethanol significantly reduced GABA currents in a manner dependent on the ratio of subunits. Conclusions: These studies demonstrate that changes in relative expression of GABA A receptor subunits alter the response of the resulting channels to GABA and to ethanol.

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