The transcription rates of the alpha 1, alpha 5, and alpha 6 gamma-aminobutyric acidA receptor subunit genes were analyzed in cultures maintained in low KCl (12.5 mM), in low KCl treated with NMDA (10 microM), and in high KCl (25 mM). alpha 1 and alpha 5 transcription rates were significantly increased in response to NMDA or high KCl treatment, while alpha 6 and cyclophilin transcription rates were not changed by either condition. These data suggest that following NMDA or high KCl treatment of granule cells, changes in alpha 1 and alpha 5 mRNA content are a consequence of a specific transcriptional rate increase of the corresponding subunit genes.