ABSENCE OF C-FOS INDUCTION IN NEONATAL RAT-BRAIN AFTER SEIZURES

Induction of the proto-oncogene c-fos is often considered to be a marker of increased neuronal activity. We have used in situ hybridization to study the pattern of c-fos expression in limbic structures following kainic acid-induced seizures during the postnatal period in the rat. Prior to postnatal day 13 (P13), seizure activity did not result in c-fos induction in an limbic structure. Between P13 and P25, a gradual increase in c-fos expression was observed in hippocampus and cortical structures. These results were corroborated by nuclear run-off transcription assay. Thus, alterations in c-fox transcription that may facilitate stimulus-transcription coupling occur during postnatal development. The possible relationship between the postnatal maturation of c-fos expression and the increase, in susceptibility of specific neuronal populations to seizure-induced cell damage is discussed.