Ethanol dissociates thiopental and GABA-receptor interaction

The effect of ethanol on thiopental and GABA-receptor interaction was studied in hippocampal slice preparations and membrane fractions. The field potentials evoked in pyramidal neurons by stratum radiatum stimulation are inhibited by GABA 10⁻⁴–10⁻³ M. Thiopental, 10⁻⁵ M, enhanced the inhibitory effect. When ethanol, 35 mM, was included, no enhancement of GABA inhibition of the field potentials by thiopental was observed. This effect of ethanol was reversible. The dissociative effect of ethanol on thiopental and GABA-receptor interaction was observed also in ³H]GABA binding experiments. In slices from rats chronically administered ethanol (2 g/kg, b.i.d., 30 days), thiopental was without effect on GABA inhibition of the field potentials. The results are discussed in relation to phenomena underlying chronic barbiturate or ethanol intoxication.