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Ionotropic GABA receptors with mixed pharmacological properties of GABAA and GABAC receptors

2004; Elsevier BV; Volume: 497; Issue: 2 Linguagem: Inglês

10.1016/j.ejphar.2004.06.044

1879-0712

Kristin Hartmann, Frank Stief, Andreas Draguhn, Christiane Frahm,

Ion channel regulation and function

Ionotropic γ-aminobutyric acid (GABA) receptors form a large family of molecular isoforms with distinct properties. We have characterized a distinct new type of GABA receptors in CA1 pyramidal cells in rat hippocampal slices. Somatic application of GABA induced currents which were partially suppressed by (1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid (TPMPA), a specific antagonist of GABAC receptors. This sensitivity was enhanced when we evoked the currents by the GABAC receptor agonist cis-4-aminocrotonic acid (CACA). However, both GABA- and CACA-evoked currents were sensitive towards bicuculline and thus lack the defining feature of GABAC receptors, which are insensitive towards this antagonist. Spontaneous miniature post-synaptic currents (mIPSCs) revealed a similar pharmacological behaviour. We conclude that juvenile CA1 pyramidal cells express a fraction of ionotropic GABA receptors with mixed pharmacological properties of both, GABAA and GABAC receptors.