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Isovaline Does Not Activate GABAB ReceptorCoupled Potassium Currents in GABAB Expressing AtT-20 Cells and Cultured Rat Hippocampal Neurons

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posted on 2023-05-18, 12:40 authored by Kimberley PitmanKimberley Pitman, Borgland, SL, MacLeod, B, Pull, E
Isovaline is a non-proteinogenic amino acid that has analgesic properties. R-isovaline is a proposed agonist of the γ-aminobutyric acid type B (GABAB) receptor in the thalamus and peripheral tissue. Interestingly, the responses to R-isovaline differ from those of the canonical GABAB receptor agonist R-baclofen, warranting further investigation. Using whole cell recording techniques we explored isovaline actions on GABAB receptors coupled to rectifying K+ channels in cells of recombinant and native receptor preparations. In AtT-20 cells transfected with GABAB receptor subunits, bath application of the GABAB receptor agonists, GABA (1 μM) and R-baclofen (5 μM) produced inwardly rectifying currents that reversed approximately at the calculated reversal potential for K+ R- isovaline (50 μM to 1 mM) and S-isovaline (500 μM) did not evoke a current. R-isovaline applied either extracellularly (250 μM) or intracellularly (10 μM) did not alter responses to GABA at 1 μM. Co-administration of R-isovaline (250 μM) with a low concentration (10 nM) of GABA did not result in a response. In cultured rat hippocampal neurons that natively express GABAB receptors, R-baclofen (5 μM) induced GABAB receptor-dependent inward currents. Under the same conditions R-isovaline (1 or 50 μM) did not evoke a current or significantly alter R-baclofeninduced effects. Therefore, R-isovaline does not interact with recombinant or native GABAB receptors to open K+ channels in these preparations.


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PL o S One



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Menzies Institute for Medical Research


Public Library of Science

Place of publication

United States

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Copyright 2015 Pitman et al. Licenced under Creative Commons Attribution 4.0 International

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