RESUMO
C-fos protein is a gene regulatory third messenger involved in long-term responses of cells to various stimuli. Kainic acid(KA), a powerful excitatory analogue, induces seizures and damages the hippocampus and other limbic regions in rats. KA treatment induces c-fos protein production in the hippocampus. This study was undertaken to investigate the expression of c-fos protein in the hippocampus according to seizure stage induced by systemic injection of KA. Twenty-three adult male Sprague-Dawley rats experienced convulsions by a single intraperitoneal injection of convulsive dose (20-40 mg/Kg) of KA. Seven control rats received normal saline. Animals were sacrificed 3 hr after KA treatment. The expression of c-fos protein was tested in the hippocampus by immunohistochemical staining using polyclonal anti-Fos. Most of the rats exhibited limbic motor epileptic activity. C-fos protein immunoreactivity increased in the CA1, CA3 and dentate gyrus at stage 1-2, and not only in the CA1, CA3 and dentate gyrus but also in the CA4 at stage 3-4. At stage 5, c-fos protein immunoreactivity increased in all areas of the hippocampus. C-fos protein immunoreactivity increased progressively with increasing severity of convulsions. These results show that KA produces limbic motor seizure associated with a rise in the c-fos protein in the hippocampus, and that the expression of c-fos protein may has some relevance to the progressive and permanent brain changes occurring during epilepsy.