c-Foss mapping of changes in neuronal activity during the course of PTZ kindling of seizures

In the present study, the c-Fos expression was used to map brain structures recruited during the evolution of seizures after repeated, administration of pentylenetetrazol at the subconvlusive dose (35 mg/kg, i.p.), in rats. It has been found that the earliest expression of cFos, at the stage 1,2 of kindling, appeared in the nucleus accumbensshell, the piriform cortex, the prefrontal cortex and striatum. On the 3rd stage of kindling, the central amygdala nucleus, the entorhinal cortex, and the lateral septal nucleus (LSV), showed an enhanced expression of c-Fos. On the 4th stage of kindling, c-Fos was increased in the basolateral amygdala, and CA1 area of the hippocampus. Finally, c-Fos labelling was enhanced in the dentate gyrus of the hippocampus, only when the stage 5 of kindling, i.e. the clonic-tonic convulsions, appeared. The most potent changes in c-Fos (in a descending order) were shown in the dentate gyrus, piriform cortex, CA1 area, the LSV, basolateral amygdala, central amygdala nuclei, and prefrontal cortex. It appeared, that there are important similarities in the structures recruited at the beginning and at the end of electrically and chemically-induced kindling, i.e. the piriform cortex and the hippocampal dentate gyrus, respectively. On the other hand, the differences gradually disappear at the later stages of kindling, followed by the symmetrical propagation of epileptic activity from the limbic system to the neocortex, during the generalized seizures.