Studies of ethanol actions on recombinant δ-containing γ-aminobutyric acid type A receptors yield contradictory results

The gamma-aminobutyric acid type A receptors (GABA(A)-Rs) display a wide variety of subunit combinations. Drugs such as benzodiazepines have shown differential effects based on GABA(A)-R subunit composition. Actions of alcohols and volatile anesthetics generally do not vary markedly with subunit composition, with low concentrations of ethanol being poor modulators of these receptors. Recent studies showed alpha(-)(4/6) and delta-containing GABA(A)-Rs (located extrasynaptically and responsible for tonic currents in selective brain regions) presenting high sensitivity to low concentrations of ethanol, but these results have not been obtained in other laboratories. We carried out additional experiments varying the receptor level of expression, and GABA and ethanol concentration, but no sensitivity to low concentrations of ethanol was detected. We will discuss these results and attempt an analysis of the possible causes for the discrepancies. (c) 2007 Elsevier Inc. All rights reserved.