Abstract: Objective: To study the effects and mechanisms of emodin on exploratory and cognitive functions of mice experiencing cerebral ischemia reperfusion. Methods: Using improved Himori method, cerebral ischemia reperfusion injury was produced in conscious mice by temporarily obstructing bilateral common carotid arteries. Effects of emodin (10.0, 1.0, 0.1 mg.kg-1，ip) on exploratory and cognitive function of mice experiencing cerebral ischemia reperfusion were assessed using the exploratory movement test and the step-through and step-down tests. The content of nitric oxide (NO) and the nitric oxide synthase (NOS) activities in brain and plasma, the content of hydrogen peroxide (H2O2) and catalase (CAT) activities in brain, and brain index were also measured. Results: Emodin significantly improved the exploratory and cognitive impairment induced by cerebral ischemia reperfusion injury, reduced the content of NO and H2O2, decreased the activities of NOS, and increased the activities of CAT and brain index. Conclusions: Emodin improved the performance in tests assessing exploratory and cognitive functions in mice experiencing cerebral ischemia reperfusion injury. Possible mechanisms include the reduction of the activities of NOS and enhancement of the activities of CAT, and clearance of the oxygen free radicals.

Key words: emodin, cerebral ischemia reperfusion, learning and memory, cognitive function, exploratory movement test