ALTERED HIPPOCAMPAL KAINATE-RECEPTOR MESSENGER-RNA LEVELS IN TEMPORAL-LOBE EPILEPSY PATIENTS

This study determined whether hippocampal kainate (KA) receptor mRNA l evels were increased or decreased in temporal lobe epilepsy patients c ompared with nonseizure autopsies, Hippocampal sclerosis (HS; n = 17), nonsclerosis (non-HS; n = 11), and autopsy hippocampi (n = 9) were st udied for KA1-2 and GluR5-7 mRNA levels using semiquantitative in situ hybridization techniques, along with neuron densities. Compared with autopsy hippocampi, HS and non-HS cases showed decreased GluR5 and Glu R6 hybridization densities per CA2 and/or CA3 pyramid. Furthermore, MS patients demonstrated increased KA2 and GluR5 hybridization densities per granule cell compared with autopsy hippocampi. These findings ind icate that chronic temporal lobe seizures were associated with differe ntial changes in hippocampal KA1-2 and GluR5-7 hybridization densities that vary by subfield and pathology group. In temporal robe epilepsy patients, these results support the hypothesis that pyramidal cell Glu R5 and GluR6 mRNA levels are decreased as a consequence of seizures, a nd in Ms patients granule cell KA2 and GluR5 mRNA levels are increased in association with aberrant fascia dentata mossy fiber sprouting and /or hippocampal neuronal loss. (C) 1998 Academic Press.