The pattern of E2F1 and c-myb immunoreactivities in the CA1 region is different from those in the CA2/3 region of the gerbil hippocampus induced by transient ischemia.

In this study, we examined transient ischemia-induced changes in transcription factor E2F1 and c-myb expressions in the gerbil hippocampus after 5 min of transient forebrain ischemia. E2F1 immunoreactivity significantly increased in the CA1 region 6-12 h after ischemia/reperfusion. c-myb immunoreactivity increased mainly in CA1 pyramidal cells with time by 12 h after ischemia. Thereafter, E2F1 and c-myb immunoreactivities significantly decreased compared to those in the 12 h post-ischemic group. Four days after ischemia/reperfusion, E2F1 and c-myb immunoreactivities were detected in non-pyramidal cells. Ten days after ischemia, c-myb immunoreactivity increased again: at this time, astrocytes as well as non-pyramidal cells showed E2F1 and c-myb immunoreactivities. In the CA2/3 region, E2F1 and c-myb immunoreactivities mainly changed in non-pyramidal cells, and 10 days after ischemia, c-myb immunoreactivity was not expressed in astrocytes. In conclusion, E2F1 and c-myb significantly alter in pyramidal cells and express in astrocytes in the gerbil hippocampal CA1 region after transient ischemia. These results indicate that E2F1 and c-myb in the CA1 region after ischemic damage may be associated with delayed neuronal death.