Hippocampal kindling increases the expression of glutamate receptor-A Flip and -B Flip mRNA in dentate granule cells.

The level of the mRNAs encoding the AMPA-selective glutamate receptors-A and -B, alternatively splice variants, Flip and Flop, was studied by in situ hybridization in the brains of rats kindled by Schaffer collateral/commissural-fiber stimulation. In comparison to control animals, the expression level of the Flip variant of both GluR-A and GluR-B mRNAs was bilaterally enhanced in the dentate granule neurons of kindled animals 24 h after last-generalized seizure, whereas no obvious alterations were observed in the GluR-A Flop and GluR-B Flop mRNA variants. In kindled animals, studied 1 month after the last seizure, GluR-A Flip and GluR-B Flip mRNA had returned to control levels. We suggest that these changes may result in an enhanced glutamate receptor sensitivity in the fascia dentata during kindling.