Prolonged ethanol inhalation decreases γ-aminobutyric acid_A receptor α subunit mRNAs in the rat cerebral cortex

Ethanol administration to rats by ethanol vapor inhalation (14 days) results in a 40-50% reduction in the level of γ-aminobutyric acid_A (GABA_A) receptor α₁ subunit mRNAs [4.4 and 4.8 kilobases (kb)] in the cerebral cortex. The level of α₂ subunit mRNA (8.0 kb) was also reduced by 29%, whereas there was no effect of prolonged ethanol exposure on the level of α₃ subunit mRNA (3.1 kb). Ethanol exposure did not alter the steady state levels of cerebral cortical glutamic acid decarboxylase or β-actin mRNAs. Moreover, no alterations in the levels of total RNA, poly(A)⁺ RNA, or rRNA were observed, suggesting that the ethanol-induced reductions in GABA_A receptor α₁ and α₂ subunit mRNAs were not the result of a generalized effect of ethanol administration on transcription or mRNA turnover. These ethanol-induced reductions in GABA_A receptor α subunit mRNAs may underlie alterations in GABA_A receptor function or number observed following prolonged ethanol exposure in rats.