Time course of c-FOS expression in status epilepticus induced by amygdaloid stimulation

Decaying of c-FOS immunoreactivity (FIR) was studied in adult rats with 1 h self-sustaining limbic status epilepticus (SSLSE) induced by amygdaloid electrical stimulation. Rats that failed to enter SSLSE showed localized FIR in the ipsilateral limbic cortex, neocortex, and amygdala. FIR became bilaterally extensive, including the hippocampal formation 0.5 h after SSLSE. It decreased gradually between 2 and 6 h and returned to basal levels around 1 day. Neocortical FIR in clonic SSLSE persisted longer than in other types of SSLSE. We demonstrate for the first time that FIR in SSLSE lasts much longer than several hours, its decaying is related to the seizure behavior, and absent or weak FIR at the hippocampal formation is associated with failed SSLSE entry.