Quantitative neuronal c-fos and c-jun expression in Alzheimer's disease.
Apoptosis, or programmed cell death, has been proposed as a mechanism of neuropathology in Alzheimer's disease (AD). Activation of immediate early genes (IEG) c-jun and c-fos appears to be required for the initiation of apoptosis. Furthermore, the expression of c-jun is induced in cultured neurons that undergo beta-amyloid-mediated apoptosis suggesting a direct role for c-jun in the apoptosis of AD neurons. Using immunohistochemical methods, we calculated the average number of neuronal profiles per unit area expressing c-Jun and c-Fos within hippocampal regions CA1, CA2/3, and CA4 in postmortem brain samples from AD patients and age-matched non-AD patients. There was an increase in c-Jun-positive and c-Fos-positive neuronal profile density in nearly all AD hippocampal regions examined. In cerebellum there was no evidence of apoptosis as determined by using TUNEL technique, and negligible c-Jun labeling.