A photoswitchable GABA receptor channel blocker

Area of Science:

• Neuroscience
• Pharmacology
• Molecular Biology

Background:

• Anion-selective Cys-loop receptors, including GABA and glycine receptors, are crucial for inhibitory neurotransmission in the central nervous system.
• Dysfunction of these receptors is linked to various neurological disorders, often managed with allosteric modulators.
• Existing GABA and glycine receptor channel blockers pose toxicity risks with systemic administration.

Purpose of the Study:

• To develop an efficient, light-controllable modulator for GABA receptors.
• To create a novel compound, azobenzene-nitrazepam (Azo-NZ1), for precise control over receptor activity.

Main Methods:

• Experiments utilized cultured cells expressing Cys-loop receptors and brain slices with patch-clamp techniques.
• Site-directed mutagenesis and molecular modeling were employed to elucidate the mechanism of action.
• Photomodulation was assessed by observing effects on GABAergic currents in neurons.

Main Results:

• Azo-NZ1, in its trans-configuration under visible light, blocked GABA_A, GABA_C, and glycine receptors.
• UV illumination induced the cis-state, restoring receptor activity.
• Azo-NZ1 effectively photomodulated GABAergic currents in dentate gyrus neurons by blocking the Cl-selective ion pore.

Conclusions:

• Azo-NZ1 functions as a soluble, light-driven chloride channel blocker for anion-selective Cys-loop receptors.
• This compound enables precise photo-modulation of GABAergic activity.
• Azo-NZ1 offers novel possibilities for studying inhibitory neurotransmission with patterned illumination.