Ligand-activation of GABAA receptors on the automated patch clamp platforms QPatch and Qube 384 using conventional electrophysiology and optopharmacology

γ-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the central nervous system (CNS) and the binding of GABA to ionotropic GABA receptors (GABA_AR) is a crucial process in the healthy brain. An imbalance of GABA secretion or the malfunction of the receptor is associated with multiple disease areas like anxiety disorders, seizures and schizophrenia. Pharmacological manipulation of the receptor has, therefore, a large therapeutic potential, which is underscored by the amount of available treatment possibilities and the ongoing search for alternatives thereof^1-4.
GABA_A receptors are ligand-gated ion-channels that consist of 5 membrane-spanning subunits^5,6 and are permeable to Cl^– ions. So far, 16 different subunits have been identified in humans (ɑ1-6, ꞵ1-3, γ1-3, δ, ε, γ, θ, π) and their composition within the GABA receptor leads to different pharmacological responses7. Here, we show pharmacological modulation of the GABA_AR using our high-throughput automated patch clamp (APC) systems QPatch and Qube 384. Our study includes a characterization of the heterogeneous GABA_AR population of cultured primary hippocampal astrocytes and an evaluation of the GABA_AR clone ɑ5ꞵ3γ2. In addition, we utilize the well-characterized GABA_AR response to establish a novel method for ligand release, namely the light-stimulated release of ruthenium-bipyridine-triphenylphosphine(RuBi)-caged GABA using light stimulation on the Qube 384 platform.

Keywords: Qube Opto, Optical, Opto, Optogenetic