Ischemic induction of protooncogene expression in gerbil brain.

Cerebral ischemia and reperfusion results in an active series of metabolic events, eventually leading to cell death. The expression of specific genes during cerebral ischemia and reperfusion may play an important, determinant role in the mechanisms controlling cellular processes. Ten minutes of bilateral carotid occlusion in the Mongolian gerbil was found to increase the messenger RNA for both the c-fos and c-jun protooncogenes. The changes in gene expression were detected in the regions of ischemia, specifically the cortex and striatum, and no increases were seen in either the brain stem or the cerebellum, which possess a separate circulation. Induction of protooncogene mRNA is correlated to the duration of ischemia, i.e., the longer the time of ischemia, the greater the increase in c-fos expression. Pretreatment of animals with pentobarbital reduced the effect of the ischemic insult and prevented the increase in c-fos mRNA. Analysis of the c-fos and c-jun proteins after ischemia demonstrated an increase in the formation of a functional transcriptional complex and association with the AP-1 binding region. These findings suggest that ischemic cell death and recovery in neurodegenerative disorders such as stroke may involve the regulated expression of these protooncogenes early in the pathway of ischemia.