Setting the time course of inhibitory synaptic currents by mixing multiple GABAA receptor α subunit isoforms

Mark D. Eyre, Massimiliano Renzi, Mark Farrant, Z. Nusser

Research output: Contribution to journalArticle

54 Citations (Scopus)

Abstract

The kinetics of IPSCs influence many neuronal processes, such as the frequencies of oscillations and the duration of shunting inhibition. The subunit composition of recombinant GABAA receptors (GABAARs) strongly affects the deactivation kinetics of GABA-evoked currents. However, for GABAergic synapses, the relationship between subunit composition and IPSC decay is less clear. Here we addressed this by combining whole-cell recordings of miniature IPSCs (mIPSCs) and quantitative immunolocalization of synaptic GABAAR subunits. In cerebellar stellate, thalamic relay, and main olfactory bulb (MOB) deep short-axon cells of Wistar rats, the only synaptic α subunit was α1, and zolpidem-sensitive mIPSCs had weighted decay time constants (τw) of 4-6 ms. Nucleus reticularis thalami neurons expressed only α3 as the synaptic α subunit and exhibited slow (τw = 28 ms), zolpidem-insensitive mIPSCs. By contrast, MOB external tufted cells contained two α subunit types (α1 and α3) at their synapses. Quantitative analysis of multiple immunolabeled images revealed small within-cell, but large between-cell, variability in synaptic α1/α3 ratios. This corresponded to large cell-to-cell variability in the decay (τw = 3-30 ms) and zolpidem sensitivity of mIPSCs. Currents evoked by rapid application of GABA to patches excised from HEK cells expressing different mixtures of α1 and α3 subunits displayed highly variable deactivation times that correlated with the α1/α3 cDNA ratio. Our results demonstrate that diversity in the decay of IPSCs can be generated by varying the expression of different GABAAR subunits that alone confer different decay kinetics, allowing the time course of inhibition to be tuned to individual cellular requirements.

Original languageEnglish
Pages (from-to)5853-5867
Number of pages15
JournalJournal of Neuroscience
Volume32
Issue number17
DOIs
Publication statusPublished - Apr 25 2012

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GABA-A Receptors
Protein Isoforms
Olfactory Bulb
Synapses
gamma-Aminobutyric Acid
Neurotransmitter Receptor
Patch-Clamp Techniques
Thalamus
Axons
Wistar Rats
Complementary DNA
Neurons
zolpidem

ASJC Scopus subject areas

  • Neuroscience(all)

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Setting the time course of inhibitory synaptic currents by mixing multiple GABAA receptor α subunit isoforms. / Eyre, Mark D.; Renzi, Massimiliano; Farrant, Mark; Nusser, Z.

In: Journal of Neuroscience, Vol. 32, No. 17, 25.04.2012, p. 5853-5867.

Research output: Contribution to journalArticle

Eyre, Mark D. ; Renzi, Massimiliano ; Farrant, Mark ; Nusser, Z. / Setting the time course of inhibitory synaptic currents by mixing multiple GABAA receptor α subunit isoforms. In: Journal of Neuroscience. 2012 ; Vol. 32, No. 17. pp. 5853-5867.
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