Benzodiazepine receptor agonists affect both binding and gating of recombinant alpha1beta2gamma2 gamma-aminobutyric acid-A receptors

Neuroreport. 2007 May 28;18(8):781-5. doi: 10.1097/WNR.0b013e3280c1e2fb.

Abstract

Benzodiazepines are known to act by enhancing the effect of gamma-aminobutyric acid-A receptor agonists. Positive modulation by benzodiazepines is typically ascribed to upregulation of agonist binding affinity but their effect on gamma-aminobutyric acid-A receptor gating remain unclear. In this work, we have used the ultrafast application system to examine the impact of flurazepam and zolpidem on recombinant alpha1beta2gamma2 gamma-aminobutyric acid-A receptors. As expected, both drugs strongly enhanced currents evoked by low [gamma-aminobutyric acid]. These compounds, however, also affected currents elicited by saturating agonist concentration. In particular, flurazepam and zolpidem reduced current amplitudes and slowed down the recovery process in paired-pulse experiments. Moreover, flurazepam accelerated the current rise time and zolpidem enhanced the rate and extent of desensitization. We propose that flurazepam and zolpidem modulate gamma-aminobutyric acid-A receptors by strong enhancement of agonist binding with a superimposed limited effect on the receptor gating.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Allosteric Regulation
  • Binding Sites / drug effects
  • Cell Line, Transformed
  • Dose-Response Relationship, Drug
  • Flurazepam / pharmacology*
  • GABA-A Receptor Agonists*
  • Humans
  • Ion Channel Gating / drug effects*
  • Ion Channel Gating / physiology
  • Membrane Potentials / drug effects
  • Patch-Clamp Techniques / methods
  • Pyridines / pharmacology*
  • Receptors, GABA-A / genetics
  • Receptors, GABA-A / metabolism*
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Transfection / methods
  • Zolpidem
  • gamma-Aminobutyric Acid / pharmacology

Substances

  • GABA-A Receptor Agonists
  • Pyridines
  • Receptors, GABA-A
  • Recombinant Proteins
  • gamma-Aminobutyric Acid
  • Zolpidem
  • Flurazepam