Optopharmacology reveals a differential contribution of native GABAA receptors to dendritic and somatic inhibition using azogabazine

NEUROPHARMACOLOGY

卷:176

Article

Mortensen, Martin¹  Huckvale, Rosemary²  Pandurangan, Arun P.³  Baker, James R.⁴  Smart, Trevor G.¹ 

[1] UCL, Dept Neurosci Physiol & Pharmacol, Gower St, London WC1E 6BT, England

[2] Inst Canc Res, 123 Old Brompton Rd, London SW7 3RP, England

[3] MRC Lab Mol Biol, Francis Crick Ave,Cambridge Biomed Campus, Cambridge CB2 0QH, England

[4] UCL, Dept Chem, 20 Gordon St, London WC1H 0AJ, England

关键词: GABA(A) receptor;    Synaptic inhibition;    Azobenzene;    Optopharmacology;    Photoisomerisation;    Gabazine;    Azogabazine;    GABA;    Homology modelling;    Computational ligand docking;    Cerebellar granule neurons;   

DOI  :  10.1016/j.neuropharm.2020.108135

来源: Elsevier

【 摘 要 】

gamma-aminobutyric acid type-A receptors (GABA(A)Rs) are inhibitory ligand-gated ion channels in the brain that are crucial for controlling neuronal excitation. To explore their physiological roles in cellular and neural network activity, it is important to understand why specific GABA(A)R isoforms are distributed not only to various brain regions and cell types, but also to specific areas of the membrane in individual neurons. To address this aim we have developed a novel photosensitive compound, azogabazine, that targets and reversibly inhibits GABA(A)Rs. The receptor selectivity of the compound is based on the competitive antagonist, gabazine, and photosensitivity is conferred by a photoisomerisable azobenzene group. Azogabazine can exist in either cis or trans conformations that are controlled by UV and blue light respectively, to affect receptor inhibition. We report that the transisomer preferentially binds and inhibits GABA(A)R function, whilst promotion of the cis-isomer caused unbinding of azogabazine from GABA(A)Rs. Using cultured cerebellar granule cells, azogabazine in conjunction with UV light applied to defined membrane domains, revealed higher densities of GABA(A)Rs at somatic inhibitory synapses compared to those populating proximal dendritic zones, even though the latter displayed a higher number of synapses per unit area of membrane. Azogabazine also revealed more pronounced GABA-mediated inhibition of action potential firing in proximal dendrites compared to the soma. Overall, azogabazine is a valuable addition to the photochemical toolkit that can be used to interrogate GABA(A)R function and inhibition.

【 授权许可】

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