Time-Course Change of Redd1 Expressions in the Hippocampal CA1 Region Following Chronic Cerebral Hypoperfusion.

Redd1, also known as RTP801/Dig2/DDIT4, is a stress-induced protein and marked changes of Redd1 expression occurs in response to hypoxia or cerebral ischemia. In the present study, we examined the time-course changes in Redd1 protein expressions in the rat hippocampal CA1 region following chronic cerebral hypoperfusion (CCH) induced by permanent bilateral common carotid arteries occlusion (2VO). Redd1 immunoreactivity in the pyramidal neurons of the hippocampal CA1 region was increased at 7 days after 2VO surgery, and then the immunoreactivity was decreased with time. Especially, very weak Redd1 immunoreactivity was observed in the hippocampal CA1 region at 28 days after 2VO surgery. Western blot analysis showed that Redd1 level in the hippocampal CA1 region was significantly increased at 7 days following CCH and significantly decreased at 28 days after 2VO surgery, compared with that of the sham-operated group. These results indicate that Redd1 expressions is markedly changed in the hippocampal CA1 region following CCH and that change of Redd1 expression may be associated with the CCH-induced neuronal damage in the hippocampal CA1 region.