Unique actions of GABA arising from cytoplasmic chloride microdomains

Negah Rahmati; Kieran P Normoyle; Joseph Glykys; Volodymyr I Dzhala; Kyle P Lillis; Kristopher T Kahle; Rehan Raiyyani; Theju Jacob; Kevin J Staley

doi:10.1523/JNEUROSCI.3175-20.2021

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Unique actions of GABA arising from cytoplasmic chloride microdomains

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Unique actions of GABA arising from cytoplasmic chloride microdomains

Negah Rahmati, Kieran P Normoyle, Joseph Glykys, Volodymyr I Dzhala, Kyle P Lillis, Kristopher T Kahle, Rehan Raiyyani, Theju Jacob and Kevin J Staley

The Journal of neuroscience, Vol.41(23), pp.4957-4975

04/26/2021

DOI: 10.1523/JNEUROSCI.3175-20.2021

PMID: 33903223

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Abstract

Developmental, cellular, and subcellular variations in the direction of neuronal Cl- currents elicited by GABAA receptor activation have been frequently reported. We found a corresponding variance in the reversal potential (EGABA) for synapses originating from individual interneurons onto a single pyramidal cell. These findings suggest a corresponding variance in the cytoplasmic concentration of Cl- ([Cl- i]) in individual dendrites. We determined [Cl-]i in the murine hippocampus and cerebral cortex of both sexes by: 1) two-photon imaging of the Cl- sensitive, ratiometric fluorescent protein SuperClomeleon (sCLM); 2) Fluorescence Lifetime IMaging (FLIM) of the Cl- sensitive fluorophore MEQ; and 3) electrophysiological measurements of EGABA by pressure application of GABA and RuBi-GABA uncaging. Fluorometric and electrophysiological estimates of local [Cl-]i were highly correlated. [Cl-]i microdomains persisted after pharmacological inhibition of cation-chloride cotransporters (CCCs), but were progressively modified after inhibiting the polymerization of the anionic macromolecule actin. These methods collectively demonstrated stable [Cl-]i microdomains in individual neurons in vitro and in vivo and the role of immobile anions on its stability. Our results highlight the existence of functionally significant neuronal Cl- microdomains that modify the impact of GABAergic inputs.Significant Statement:Microdomains of varying chloride concentrations in the neuronal cytoplasm are a predictable consequence of the inhomogeneous distribution of anionic polymers such as actin, tubulin, and nucleic acids. Here, we demonstrate the existence and stability of these microdomains, as well as the consequence for GABAergic synaptic signaling: each interneuron produces a postsynaptic GABAA response with a unique reversal potential. In individual hippocampal pyramidal cells, the range of GABAA reversal potentials evoked by stimulating different interneurons was over 20 mV. Some interneurons generated postsynaptic responses in pyramidal cells that reversed at potentials beyond what would be considered purely inhibitory. Cytoplasmic chloride microdomains enable each pyramidal cell to maintain a compendium of unique postsynaptic responses to the activity of individual interneurons.

Details

Title: Subtitle: Unique actions of GABA arising from cytoplasmic chloride microdomains
Creators: Negah Rahmati - Harvard Medical School and Massachusetts General Hospital, Department of Neurology, Boston, MA, USA
Kieran P Normoyle - Harvard Medical School and Massachusetts General Hospital, Department of Neurology, Boston, MA, USA
Joseph Glykys - University of Iowa, Department of Pediatrics and Neurology, Iowa Neuroscience Institute, Carver College of Medicine, Iowa City, IA, USA
Volodymyr I Dzhala - Harvard Medical School and Massachusetts General Hospital, Department of Neurology, Boston, MA, USA
Kyle P Lillis - Harvard Medical School and Massachusetts General Hospital, Department of Neurology, Boston, MA, USA
Kristopher T Kahle - Yale School of Medicine, Departments of Neurosurgery, Pediatrics, and Cellular & Molecular Physiology, New Haven, CT, USA
Rehan Raiyyani - Harvard Medical School and Massachusetts General Hospital, Department of Neurology, Boston, MA, USA
Theju Jacob - Harvard Medical School and Massachusetts General Hospital, Department of Neurology, Boston, MA, USA
Kevin J Staley - Harvard Medical School and Massachusetts General Hospital, Department of Neurology, Boston, MA, USA staley.kevin@mgh.harvard.edu
Resource Type: Journal article
Publication Details: The Journal of neuroscience, Vol.41(23), pp.4957-4975
DOI: 10.1523/JNEUROSCI.3175-20.2021
PMID: 33903223
NLM abbreviation: J Neurosci
eISSN: 1529-2401
Publisher: United States
Language: English
Date published: 04/26/2021
Academic Unit: Neurology; Stead Family Department of Pediatrics; Iowa Neuroscience Institute; Neurology (Pediatrics)
Record Identifier: 9984071795502771

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