Alterations in the expression of mRNA for GABAA receptor alpha 1-subunit were analyzed in the brain using mice that had been made alcohol-dependent, and exhibited a decrease in GABA-dependent 36Cl- influx into membrane vesicles following continuous ethanol inhalation for 7 days. Continuous ethanol inhalation for more than 5 days induced a significant increase in the expression of GABAA receptor alpha 1-subunit mRNA in the brain without significantly altering total poly(A)+ RNA content. Furthermore, it was found that the increase in expression of GABAA receptor alpha 1-subunit mRNA in the brain turned to its normal level 8 h after the ethanol inhalation was terminated. In contrast, the expression of beta-actin mRNA in the brain was not altered under the same experimental conditions. These results suggest that continuous ethanol inhalation may induce not only the suppression of the functions of GABAA receptor complex but also a reactive increase in the expression of mRNA for GABAA receptor subunits in the brain.