AUTHOR=Wyroślak Marcin , Dobrzański Grzegorz , Mozrzymas Jerzy W. 

TITLE=Bidirectional plasticity of GABAergic tonic inhibition in hippocampal somatostatin- and parvalbumin-containing interneurons

JOURNAL=Frontiers in Cellular Neuroscience

VOLUME=Volume 17 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/cellular-neuroscience/articles/10.3389/fncel.2023.1193383

DOI=10.3389/fncel.2023.1193383

ISSN=1662-5102

ABSTRACT=GABAA receptors present in extrasynaptic areas mediate tonic inhibition in hippocampal neurons regulating thus the performance of neural networks. Here, we investigated the effect of NMDA-induced plasticity on tonic inhibition in somatostatin- and parvalbumin-containing interneurons. Using pharmacological methods and transgenic mice (SST-Cre/ PV-Cre x Ai14) we induced plasticity of GABAergic transmission in somatostatin- and parvalbumin-containing interneurons by a brief (3 min) application of NMDA. In the whole-cell patch-clamp configuration we measured tonic currents enhanced by specific agonists (etomidate or gaboxadol). Furthermore, in both control and NMDA-treated groups we examined to what extent these changes depend on regulation of distinct subtypes of GABAA receptors. Tonic conductance in the somatostatin-containing (SST+) interneurons is enhanced after NMDA application and the observed effect is associated with increased content of α5-containing GABAARs. Both fast-spiking and non-fast spiking parvalbumin-positive (PV+) cells showed reduction of tonic inhibition after the plasticity induction. This effect was accompanied in both PV+ interneuron types by a strongly reduced proportion of δ-subunit containing GABAARs and a relatively small increase in currents mediated by α5-containing GABAARs. Both somatostatin- and parvalbumin-containing interneurons show cell type-dependent and opposite sign plasticity of tonic inhibition. The underlying mechanisms depend on the cell-specific balance of plastic changes in contents of α5 and δ subunit-containing GABAARs.