Abstract
The gamma-aminobutyric acid (GABA) receptor is the major inhibitory receptor in vertebrate and invertebrate brains. Activation of this GABA A receptor, which traverses the membrane, results in its opening of an anionic channel that is part of the receptor protein and permeation of Cl- along its concentration gradient. Thus, Cl influxes producing membrane hyperpolarization.6,11 This GABA A receptor is inhibited competitively by bicuculline and allosterically by picrotoxinin and t-butylbicyclophosphorothionate (TBPS), which bind to another site that is closely associated with the Cl- channel component of the receptor protein. The GABAA receptor is studied biochemically by the characteristics and specificity or its binding of [35S]TBPS and also by monitoring its function in vitro, i.e. 36C1 influx that is induced by binding of GABA to the receptor in membrane vesicles, is inhibited by competitive and noncompetitive inhibitors and is potentiated by certain modulators. GABA A receptors also have a site that binds benzodiazepines and another that binds depressant barbiturates.14 Benzodiasepines are mostly potentiators of GABA receptor function (e.g., diazepam) increasing the receptor’s affinity for GABA and facilitating the frequency of opening of its Cl- channel, but a few benzodiazepines are inhibitors of diazepam action. There are also benzodiazepine modulators of receptor function, acting as convulsants or proconvulsants and thus are called inverse agonists (e.g., ethyl β-carboline-3-carboxylate).
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© 1990 Plenum Press, New York
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Eldefrawi, M.E., Gant, D.B., Eldefrawi, A.T. (1990). The GABA Receptor and the Action of Tremorgenic Mycotoxins. In: Pohland, A.E., et al. Microbial Toxins in Foods and Feeds. Springer, Boston, MA. https://doi.org/10.1007/978-1-4613-0663-4_27
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DOI: https://doi.org/10.1007/978-1-4613-0663-4_27
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