Neuroprotective effects of ischemic adaptation on cogni- tive dysfunction in mice with cerebral ischemia-reperfu- sion injury

Abstract

Objective: To observe the effects of remote ischemia on cognitive function and neuronal pathological damage in rats with cognitive impairment induced by bilateral common carotid artery occlusion (BCAO). Methods: Male SD rats were selected to establish the cognitive impairment model induced by cerebral ischemia reperfusion caused by BCAO. The tests included three groups of rats: a sham group, a model group with vascular cognitive impairment (VCI) , and a remote ischemic conditioning (RIC) group (VCI + RIC group). From 24 h after operation, both hind limbs of rats in VCI+RIC group were treated with RIC. After 28 d, Morris water maze test and HE staining was used to observe the pathological changes of white matter and hippocampus in each group. Results: After 3 d mice in VCI group began to improve gradually. The recovery of rats in the VCI + RIC group was relatively slow, but they started to recover rapidly 2 d after the operation. Morris water maze test showed that the escape latency of rats in VCI group and VCI+RIC group was longer than that in the sham group, and the score of VCI+RIC group was better than that of the VCI group, but there was a significant difference between the two groups (P＜0.05). The space exploration experiment was performed at 7 d and 28 d after the operation; the VCI+RIC group outperformed the VCI group in both trials; the difference between the two groups was statistically significant (P＜0.05). In the target quadrant exploration time, the difference between the VCI group (33.5±11.3 s) and the VCI+RIC group (41.2±9.7 s) was statistically significant (P＜0.05). Results from the hematoxylin and eosin (HE) staining showed that compared with VCI group, cortical cells in VCI + RIC group had loose stroma, thinner nerve fibers, fewer broken cells, and slightly shrunken cells. Compared with VCI group, neurons in VCI + RIC group had a little vacuolar degeneration and slightly shrunken cell volume. Conclusion: Cerebral ischemia-reperfusion injury can cause learning and memory impairment in rats, leading to VCI. RIC can significantly improve VCI and play a neuroprotective role.

Keywords

remote ischemic conditioning / cerebral ischemia-reperfusion / cognitive impairment / hippocampal changes / neuroprotection