Effects of hypoxic preconditioning on learning and memory in mice with cerebral ischemia-reperfusion injury and underlying mechanisms

Abstract

Objective To investigate the effects of hypoxic preconditioning on learning and memory and the possible protective mechanism in mice with cerebral ischemia-reperfusion injury. Methods Healthy adult male Kunming mice were randomly divided into five groups by Random number table: normal group(N group), hypoxic preconditioning group (HPC group), sham operation group (C group), ischemia-reperfusion group(O group), hypoxic preconditioning and ischemia-reperfusion group(HPC+ O group). HPC+ O group were given hypoxic preconditioning before 24h of ischemia- reperfusion. The escape latency was detected by Morris water maze and the neuron apoptosis of CA1 area of hippocampal was determined by immunofluorescence technique. Results The escape latency in HPC+ O group on the second, third and fourth day of MWM was (39.92±4.52)s, (30.98±2.44)s, (19.69±4.27)s, and significantly lower than that in O group((54.35±3.66)s, (46.31±4.81)s, (36.81±3.86)s). Mice in HPC+ O spent longer time in the target quadrant than that in O group((36.44±5.33)% and(24.5±2.59)%, respectively, P<0.05). Immunofluorescence showed that the apoptotic ration of nerve cells in hippocampal CA1 was significantly lower than that in O group(1.17±0.14 and 1.35±0.14, P<0.05). Conclusion Hypoxic preconditioning can increase hippocampal CA1 neurons hypoxia tolerance of ischemia reperfusion injury in mice, and reduce the incidence of neural cell apoptosis. Key words: Hypoxic preconditioning; Ischemia-reperfusion; Learning and memory; Apoptosis