Effect of ethanol administration and withdrawal on GABA receptor binding in rat cerebral cortex

Sodium independent GABA receptor binding was measured in synaptosomes prepared from cerebral cortex of rats made ethanol dependent by three daily ethanol administrations. In rats sacrificed 1 hour after the last ethanol dose there was a lower number of low affinity binding sites and lower affinity of the high affinity binding than in controls. The decreased affinity was present only in rats who showed symptoms of ethanol withdrawal during the course of ethanol administration. In rats sacrificed during ethanol withdrawal the affinity of the high affinity binding was lower than in controls and other binding characteristics were unchanged. This decreased binding was normalized by repeated Triton X-100 incubations indicating involvement of an endogenous inhibitor in this ethanol effect. Acute ethanol administration did not change GABA receptor binding.