Aging-related changes in IGF-II and c-fos gene expression in the rat brain

The protein products of growth factor genes such as IGF-II and cellular oncogenes such as c-fos are believed to be necessary for the support of normal neuronal function. Steady-state levels of c-fos and IGF-II mRNA were determined in the brain of young and old rats, using Northern analysis. Both RNAs were found to be decreased in the brain of aged rats. Age-related decrease was detected in the hippocampus, hypothalamus, striatum, cerebral cortex and cerebellum, for IGF-II mRNA, and in the cerebral cortex and cerebellum for c-fos mRNA. Furthermore, changes in the degree and pattern of DNA methylation were noted at both gene loci, in the aged rat brain. Our results could reflect changes at the genomic level possibly related to the process of aging and the accompanying decline in brain function.