Remote ischemic preconditioning improves spatial learning and memory ability after focal cerebral ischemia-reperfusion in rats

Abstract

Using a rodent model of middle cerebral artery occlusion (MCAO), we investigated the effect of remote ischemic preconditioning (RIPC) on spatial learning and memory ability after focal cerebral ischemia-reperfusion (I/R). Thirty-six male Sprague-Dawley rats were randomly allocated into 3 groups (n=12, each): sham group, rats were subjected to sham operations without MCAO and RIPC; I/R group, rats were subjected to 1h of MCAO followed by 3 days of reperfusion; I/R+RIPC group, rats were subjected to RIPC and 1h MCAO followed by 3 days of reperfusion. The spatial learning and memory ability of the rats was measured by the Morris water maze task.The activity of cholineacetyltransferase (ChAT) in the hippocampus CA1 region was observed by an immunohistochemistry method. In the Morris water maze task, MCAO elicited a significant decrease of the ability of spatial learning and memory in contrast to the sham group. Meanwhile, RIPC induced a significantly shorter prolongation of the escape latency (p<0.05); greater number passing through the platform (p<0.05) and less time for exploring the target quadrant (p<0.05) as compared with values for the I/R group. Furthermore, the number of ChAT positive cells in the CA1 region in the I/R+RIPC group was strikingly more than those of the I/R group (p<0.05). RIPC could improve the ability of spatial learning and memory after focal cerebral ischemia-reperfusion probably due to its protection of the cholinergic neurons in the hippocampal CA1 region.