Trimethyltin-induced c-fos expression: adolescent vs neonatal rat hippocampus.

In the adult animal, the immediate early genes such as c-fos and c-jun, and other activity-dependent genes such as ornithine decarboxylase (ODC) are induced within minutes to hours in response to perturbations to the cellular environment. We have examined the induction of these genes following acute exposure to trimethyltin (TMT) using Northern blot analysis. The induction of these genes within the hippocampus and the cerebellum was examined half an hour following acute exposure to TMT (4 mg/kg, sc). In the neonatal (PND 4) rat hippocampus, the basal expression of c-fos, c-jun, and ODC appeared to be unaltered following TMT exposure. However, in the adolescent (PND 35) rat, TMT exposure produced a dramatic induction of c-fos mRNA in the hippocampus within half an hour, while beta-actin expression remained constant. No TMT-induced changes in the expression of c-fos were seen in the cerebellum of adolescent animals. Furthermore, expression of c-jun mRNA was not altered in either the mature hippocampus or the cerebellum half an hour following TMT exposure. These results suggest that c-fos may be involved in the response of the brain to TMT in an age-dependent and region-specific manner.