ABSTRACT
BACKGROUND: Immediate early gene (IEG) is supposed to be linked in the continuous seizure induced long-term changes of specific neurons. We tried to investigate the effects of focal interictal epileptiform discharges on the c-JUN expression in the rat brain which is not clearly understood. METHODS:Epidural electrodes were placed on a male Sprague-Dawley weighing 150~230 g and benzathine penicillin (Pc) was applied cortically. After focal interictal epileptiform discharges were successfully identified, EEG was recorded regularly. Cardiac perfusion and extraction of the brain was done at 2, 4, 24 hours and 1 week after the Pc application. Sixteen rats were evenly distributed into 4 groups. Immunocytochemical staining with specific antisera (Santa Cruz) was performed. RESULTS: The epileptiform discharges were induced within an hour after topical Pc applications. At 2 hours after Pc application, c-JUN was moderately expressed in the dentate gyrus (DG) and weakly expressed in the CA3 pyramidal cell, amygdala, pyriform cortex, thalamus, and neocortex. At 4 hours, c-JUN was minimally expressed in DG and other regions. Whereas, at 24 hours, c-JUN was maximally expressed in the DG and also in the CA3 pyramidal cell, amygdala, pyriform cortex, thalamus, and neocortex. One week after Pc application, c-JUN was moderately expressed in the DG and weakly expressed in the CA3 pyramidal cell, amygdala, pyriform cortex, and neocortex. CONCLUSIONS: This data showed that even focal interictal epileptic activity can induce IEG encoded c-JUN protein in the specific distant brain regions of a rat until a late period and the expression pattern showed a synchronous and bimodal pattern.