Behavioral and Histochemical Studies in Repeated Cerebral Ischemia in Rats

Abstract

In the behavioral study, we have reported that the 10 min transient cerebral ischemia of the rat caused the deficit of spatial cognition in 8-arm radial maze task 24 hours after re-perfusion.¹ Using this model, we have developed new drugs, so called nootropic drugs. But, unfortunately, many of them were not effective in the clinical use. We considered the reasons why this model did not work as an animal model for cerebrovascular dementia and resulted that the 10 min cerebral ischemia was too weak to produce hippocampal cell death. Recently, Kato et al.² suggested that the hippocampal cell death was suppressed when the brief time ischemia was repeated with 6 hours or more intervals and was enhanced, on the contrary, by less than 6 hours intervals. In the present study, we applied the repeated 10 min ischemia with 1 hour interval for producing more severe ischemic insult and evaluated whether this model was more useful as a new animal model for cerebrovascular dementia.