Interrogating the function of GABAA receptors in the brain with optogenetic pharmacology

To better understand neural circuits and behavior, microbial opsins have been developed as optogenetic tools for stimulating or inhibiting action potentials with high temporal and spatial precision. However, if we seek a more reductionist understanding of how neuronal circuits operate, we also need high-resolution tools for perturbing the function of synapses. By combining photochemical tools and molecular biology, a wide variety of light-regulated neurotransmitter receptors have been developed, enabling photo-control of excitatory, inhibitory, and modulatory synaptic transmission. Here we focus on photo-control of GABA(A) receptors, ligand-gated CI- channels that underlie almost all synaptic inhibition in the mammalian brain. By conjugating a photoswitchable tethered ligand onto a genetically-modified subunit of the GABA(A) receptor, light-sensitivity can be conferred onto specific isoforms of the receptor. Through gene editing, this attachment site can be knocked into the genome, enabling photocontrol of endogenous GABA(A) receptors. This strategy can be employed to explore the cell biology and neurophysiology of GABA(A) receptors. This includes investigating how specific isoforms contribute to synaptic and tonic inhibition and understanding the roles they play in brain development, long-term synaptic plasticity, and learning and memory.

Automated summary

To better understand neural circuits and behavior, scientists have developed microbial opsins as optogenetic tools for precise stimulation or inhibition of action potentials. Additionally, they have also developed light-regulated neurotransmitter receptors to perturb synaptic function at high resolution.