RNA editing at the Q/R site for the glutamate receptor subunits GLUR2, GLUR5, and GLUR6 in hippocampus and temporal cortex from epileptic patients

Posttranscriptional editing of mRNA is a phenomenon that generates molecula r heterogeneity and functional variety. With the intention to test if RNA e diting plays a role in pathological processes, which contribute to seizure maintenance, we examined the ratio of the unedited (Q) to edited (R) form o f the AMPA receptor subunit GluR2 and kainate receptor subunits GluR5 and G luR6 in the hippocampus and temporal cerebral cortex, both excised from pat ients with pharmacoresistant temporal lobe epilepsies. We compared the data with samples from nonepileptic human control tissue (autopsy tissue). The ratio of Q/R editing was analyzed by means of reverse transcription-polymer ase chain reaction followed by a restriction enzyme assay. We found that th e editing efficiency for the kainate receptor subunits GluR5 and GluR6 was significantly higher in temporal cortex than in normal controls. The altera tion in GluR5 and GluH6 mRNA editing in the neocortical tissue may reflect an adaptive reaction of ongoing seizure activity to prevent excessive Ca2influx. (C) 2001 Academic Press.