Seizure activity causes a rapid increase in sulfated glycoprotein-2 messenger RNA in the adult but not the neonatal rat brain.

The present study investigated the changes in sulfated glycoprotein-2 (SGP-2) messenger RNA at various times following kainic acid-induced seizure onset in adult and neonatal rat brain. Double labelling using immunostaining of the astrocyte-specific glial fibrillary acidic protein indicated that SGP-2 expression was rapidly and transiently increased in granule cells of the dentate gyrus up to 8 hours after seizure onset. Thereafter, and up to 7 days following seizure onset, the majority of cells exhibiting increased SGP-2 expression were astrocytes located in the molecular layer of the dentate gyrus and in the alveus, as well as in regions adjacent to CA3 and CA1 pyramidal cells. No increase in SGP-2 mRNA was detected in pyramidal neurons selectively damaged by KA. In addition, increased expression of SGP-2 following KA administration was not observed in neonatal rat hippocampus prior to postnatal day 21. The results argue against a role for SGP-2 in KA-induced neuronal death and demonstrate a surprisingly rapid increase in astroglial gene expression following seizure activity, thus supporting a role for SGP-2 in synaptic plasticity.