title: Synthesis and biological evaluation of bis-CNB-GABA, a photoactivatable neurotransmitter with low receptor interference and chemical two-photon uncaging properties.
abstract: Photoactivatable "caged" neurotransmitters allow optical control of neural tissue with high spatial and temporal precision. However, the development of caged versions of the chief vertebrate inhibitory neurotransmitter, γ-amino butyric acid (GABA), has been limited by the propensity of caged GABAs to interact with GABA receptors. We describe herein the synthesis and application of a practically useful doubly caged GABA analog, termed bis-α-carboxy-2-nitrobenzyl-GABA (bis-CNB-GABA). Uncaging of bis-CNB-GABA evokes inward GABAergic currents in cerebellar molecular layer interneurons with rise times of 2 ms, comparable to flash duration. Response amplitudes depend on the square of flash intensity, as expected for a chemical two-photon uncaging effect. Importantly, prior to uncaging, bis-CNB-GABA is inactive at the GABAA receptor, evoking no changes in holding current in voltage-clamped neurons and showing an IC50 of at least 2.5 mM as measured using spontaneous GABAergic synaptic currents. Bis-CNB-GABA is stable in solution, with an estimated half-life of 98 days in the light. We expect that bis-CNB-GABA will prove to be an effective tool for high-resolution chemical control of brain circuits.
authors.affiliation: Department of Psychology, ‡Department of Chemistry, §Department of Molecular Biology and Neuroscience Institute, Princeton University , Princeton, New Jersey 08544, United States.
authors.forename: Diana D
authors.initials: DD
authors.lastname: Shi
authors.forename: Federico F
authors.initials: FF
authors.lastname: Trigo
authors.forename: Martin F
authors.initials: MF
authors.lastname: Semmelhack
authors.forename: Samuel S-H
authors.initials: SS
authors.lastname: Wang
mesh_terms: D000818:Animals; D002531:Cerebellum / Q000187:drug effects / Q000378:metabolism; D004355:Drug Stability; D005071:Evoked Potentials / Q000187:drug effects; D007395:Interneurons / Q000187:drug effects / Q000378:metabolism; D015394:Molecular Structure; D018377:Neurotransmitter Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D010648:Phenylacetates / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D055668:Photochemical Processes; D017785:Photons; D018079:Receptors, GABA / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects; D005680:gamma-Aminobutyric Acid / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology
chemical_list: D018377:Neurotransmitter Agents; D010648:Phenylacetates; D018079:Receptors, GABA; C109231:alpha-carboxy-2-nitrobenzyl gamma-aminobutyrate; D005680:gamma-Aminobutyric Acid