Biochemical and immunohistochemical correlates of kindling-induced epilepsy: role of calcium binding protein.

The levels and distribution of calcium binding protein (CaBP) were examined in the central nervous system of rats exhibiting kindling-induced epilepsy. Following commissural kindling, the concentration of CaBP in the hippocampal formation was significantly reduced but no change was observed in levels of total soluble protein or calmodulin, another calcium-related protein. Histochemical examination of kindled animals revealed a localized depletion of CaBP-like immunoreactivity restricted to the dentate granule cell-mossy fiber system of the hippocampal formation. These data demonstrate a correlation between the loss of CaBP from dentate granule cells and kindling-induced epilepsy, the underlying mechanism of which may involve an impairment of granule cells to regulate their intracellular calcium environment when challenged with high frequency electrical stimulation.