Unique Actions of GABA Arising from Cytoplasmic Chloride Microdomains

• DOI: 10.1523/jneurosci.3175-20.2021
• Publication Date: 2021-04-26T17:55:06Z
• Authors: Negah Rahmati; Kieran P. Normoyle; Joseph Glykys; Volodymyr I. Dzhala; Kyle P. Lillis; Kristopher T. Kahle; Rehan Raiyyani; Theju Jacob; Kevin J. Staley
• Keywords: Neurons; Cytoplasm; Mice; 0303 health sciences; 03 medical and health sciences; Chlorides; Animals; Synaptic Transmission; gamma-Aminobutyric Acid

Developmental, cellular, and subcellular variations in the direction of neuronal Cl^– currents elicited by GABA_A receptor activation have been frequently reported. We found a corresponding variance reversal potential (E_GABA) for synapses originating from individual interneurons onto single pyramidal cell. These findings suggest similar heterogeneity cytoplasmic intracellular concentration chloride ([Cl^–]_i) dendrites. determined [Cl^–]_i murine hippocampus cerebral cortex both sexes (1) two-photon imaging Cl^–-sensitive, ratiometric fluorescent protein SuperClomeleon; (2) Fluorescence Lifetime IMaging (FLIM) Cl^–-sensitive fluorophore MEQ (6-methoxy-<i>N</i>-ethylquinolinium); (3) electrophysiological measurements E_GABA pressure application GABA RuBi-GABA uncaging. Fluorometric estimates local were highly correlated. microdomains persisted after pharmacological inhibition cation–chloride cotransporters, but progressively modified inhibiting polymerization anionic biopolymer actin. methods collectively demonstrated stable neurons <i>in vitro</i> vivo</i> role immobile anions its stability. Our results highlight existence functionally significant that modify impact GABAergic inputs. <b>SIGNIFICANCE STATEMENT</b> Microdomains varying concentrations cytoplasm are predictable consequence inhomogeneous distribution polymers such as actin, tubulin, nucleic acids. Here, we demonstrate stability these microdomains, well synaptic signaling: each interneuron produces postsynaptic response with unique potential. In hippocampal cells, range potentials evoked stimulating different was &gt;20 mV. Some generated responses cells reversed at beyond what would be considered purely inhibitory. Cytoplasmic enable cell to maintain compendium activity interneurons.