Chronological expression and its significance of c-jun and c-fos mRNA in rat brain

We investigated the expression of c-jun and c-fos proto-oncogenes and their distribution in the brain of newborn to adult rats to determine the relationship between protooncogene expression and brain development, by the reverse transcription-polymerase chain rection (RT-PCR) method, in situ hybridization and immunohistochemistry. In the RT-PCR analysis, the cDNA fragments of c-jun and c-fos were amplified with expected-sizes, and the expression levels were fixed through all ages examined. The in situ hybridization showed that the expression of c-jun and c-fos mRNA was located at the cytoplasm of most neurons and some glial cells of the entire portions of the cerebrum, brainstem and cerebellum until 300 days after birth. c-Jun protein immunoreactivity was detected in the nucleus of neurons which demonstrated a positive signal by in situ hybridization. Our results suggest that even after neuroblasts differentiate to mature neurons, c-jun and c-fos genes may have a role in the preservation of the neuronal function of the rat central nervous system.