Flumazenil selectively prevents the increase in α 4 ‐subunit gene expression and an associated change in GABA A receptor function induced by ethanol withdrawal

The actions of ethanol on γ‐aminobutyric acid type A (GABA A ) receptors are still highly controversial issues but it appears that some of its pharmacological effects may depend on receptor subunit composition. Prolonged ethanol exposure produces tolerance and dependence and its withdrawal alters GABA A receptor subunit gene expression and function. Whereas benzodiazepines are clinically effective in ameliorating ethanol withdrawal symptoms, work in our laboratory showed that benzodiazepines also prevent, in vitro , some of the ethanol withdrawal‐induced molecular and functional changes of the GABA A receptors. In the present work, we investigated the effects, on such changes, of the benzodiazepine receptor antagonist flumazenil that can positively modulate α 4 ‐containing receptors. We here report that flumazenil prevented both the ethanol withdrawal‐induced up‐regulation of the α 4 ‐subunit and the increase in its own modulatory action. In contrast, flumazenil did not inhibit ethanol withdrawal‐induced decrease in α 1 ‐ and δ‐subunit expression as well as the corresponding decrease in the modulatory action on GABA A receptor function of both the α 1 ‐selective ligand zaleplon and the δ‐containing receptor preferentially acting steroid allopregnanolone. These observations are the first molecular and functional evidence that show a selective inhibition by flumazenil of the up‐regulation of α 4 ‐subunit expression elicited by ethanol withdrawal.