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

Eur J Pharmacol. 2004 Aug 23;497(2):139-46. doi: 10.1016/j.ejphar.2004.06.044.


Ionotropic gamma-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 GABA(C) receptors. This sensitivity was enhanced when we evoked the currents by the GABA(C) 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 GABA(C) 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, GABA(A) and GABA(C) receptors.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bicuculline / pharmacology
  • Dose-Response Relationship, Drug
  • GABA-A Receptor Agonists
  • GABA-A Receptor Antagonists
  • Hippocampus / drug effects
  • Hippocampus / physiology
  • Rats
  • Rats, Wistar
  • Receptors, GABA / physiology*
  • Receptors, GABA-A / physiology*
  • gamma-Aminobutyric Acid / pharmacology


  • GABA-A Receptor Agonists
  • GABA-A Receptor Antagonists
  • GABA-C receptor
  • Receptors, GABA
  • Receptors, GABA-A
  • gamma-Aminobutyric Acid
  • Bicuculline