Kainate-induced seizure activity causes persistent changes in the hippocampus that include synaptic reorganization and functional changes in the messy fibers. Using in situ hybridization histochemistry, the expression of PKCα, PKCβ, PKCγ, PKCδ and PKCε mRNAs was investigated in the hippocampus of adult rats following seizures induced by a s.c. injection of kainic acid. In CA1 and CA3, we found a significant decrease in PKCγ mRNA 1 day after kainic acid which persisted for a 2nd day in CA1. None of the other PKC isoform mRNAs were altered in CA1 or CA3. In granule cells, a significant up-regulation specific to PKCε mRNA was observed. One week after kainic acid administration, a marked increase in PKCε immunoreactivity was found that persisted 2 months after kainic acid administration. PKCε immunoreactivity was found associated with messy fibers projecting to the hilus of the dentate gyrus and to the stratum lucidum of the CA3 field and presumably with the newly sprouted messy fibers projecting to the supragranular layer. These data provide the first evidence for a long-lasting increase of the PKCε in the axons of granule cells caused by kainate-induced seizures and suggest that PKCε may be involved in the functional and/or structural modifications of granule cells that occur after limbic seizures.
- Neuronal plasticity
- Temporal lobe epilepsy
ASJC Scopus subject areas
- Molecular Biology
- Cellular and Molecular Neuroscience