Region-specific changes in GABAA receptor delta subunit mRNA level by tolerance to and withdrawal from pentobarbital.

The aim of this study was to investigate whether the mRNA level of gamma-aminobutyric acid (GABA)A receptor delta subunit could be altered by chronic pentobarbital treatment. Male ICR mice were rendered tolerant to and dependent upon pentobarbital by repeated pentobarbital administration and by abrupt pentobarbital withdrawal, respectively. The levels of the delta subunit mRNA in the frontal cortex and cerebellum were quantified using RNase protection assay in the presence of the housekeeping gene, glyceraldehyde-3-phosphate dehydrogenase, as an internal standard. Our results revealed that the delta subunit mRNA in the cerebellum was upregulated in pentobarbital-tolerant mice and was downregulated in pentobarbital-withdrawn mice. No significant changes were found in the frontal cortex. These results suggest that chronic pentobarbital exposure can modify the expression of GABAA receptor delta subunit in a region-specific manner.