The Effects And Mechanism Of Esculin On Learning-memory Function After Hypoxia In Mice

ObjectiveThis experiment mainly observed the effects of Chinese herbal escolin（ESCU）on acute,fatigue and chronic hypoxia,also observed the effects and mechanism on learning-memory function after chronic hypoxia in mice,to provide theoretical support and drug targets for clinical treatment of ischemic and hypoxic diseases.MethodsIn this study,mice were selected as experimental objects,and each part of the experiment was randomly divided into 4 groups,including control group of different hypoxia models（nature blank group）,and the low,medium and high dose group（ESCU-L,ESCU-M,ESCU-H group）,and the experimental results were determined after 4 weeks of administration.The acute hypoxia-resistant experiments include:sodium nitrite acid experiment and carbon monoxide poisoning survival experiment were used,to observe the effect of escolin on hypoxia resistance in mice.The anti-fatigue effect of escolin was measured by mouse tail suspension experiment,mouse torophlico fatigue experiment,and exhausting swimming experiment.In addition,the effects of ESCU on learning and memory in chronic hypoxia were investigated by Morris water maze behavioral experiment.After water maze test,blood urea nitrogen（BUN）,lactate dehydrogenase（LDH）and glycogen contents were determined,and the tail oxygenation was tested to observe the effect of chronic hypoxia in mice.After chronic hypoxia,the heart and lung tissues of mice in each group were taken for pathological examination.Enzyme-linked immunosorbent assay（ELISA）was used to test the activities of glucose transporter-4（GLUT-4）,Na⁺-K⁺-ATP enzyme and succinate dehydrogenase（SDH）in serum.Western blotting was used to test the expression of AMPK,p-AMPK and PGC-1αto investigate the mechanism of ESCU on learning and memory ability after chronic hypoxia.Results1.The effect of ESCU on acute hypoxia resistance in mice:（1）In the sodium hypoxia-resistance experiment,the survival time of ESCU-L,ESCU-M,ESCU-H group was significantly prolonged.（2）Sodium nitrite poisoning survival experiment,ESCU-L,ESCU-M,ESCU-H group survival time significantly prolonged,compared with the control group,there was a significant difference（P<0.05）.（3）In the CO poisoning experiment,compared with the control group,the low,medium and high dose group given to the ESCU can significantly prolong the survival time of the mice,there is a significant difference（P<0.05）.2.The effect of escolin on anti-fatigue in mice:（1）In the mouse tail suspension experiment,compared with the control group,the low,medium and high dose group given to the escolin,the time of struggle in mice was significantly extended,with significant differences（P<0.05）.（2）In the mice rotated-rod fatigue experiment,compared with the control group,the low,medium and high dose group was given to the ESCU,the clockwise mode and the counterclockwise mode were significantly extended.In addition,the use of clockwise mode of uniform speed and uniform acceleration of the two movement modes,different doses of escolin can also extend the turn time.Compared with the control group,there are significant differences（P<0.05）.（3）In the swimming exhaustion experiment,compared with the control group,the low,medium and high dose group given to the escolin,the swimming time of mice was significantly extended,the time of struggle in mice,learning to swim time was significantly shortened,swimming time was shortened,but the floating time was shortened,ESCU can significantly improve the anti-fatigue swimming ability of mice,with significant differences（P<0.05）.3.The influence of ESCU on learning and memory ability after chronic CO₂ retention hypoxia:In the training of d6 space exploration experiment of morris water maze,escolin low,medium and high dose group,the original platform quadrant swimming time accounted for the total swimming time were significantly reduced,escape incubation period and swimming distance were shortened,compared with the control group has significant differences（P<0.05）.4.The effect of ESCU on serum biochemical index and energy metabolism:ESCU can significantly reduce the contents of lactic acid and urea nitrogen,increase Sp O₂.The activities of GLUT-4 and Na⁺-K⁺-ATP enzyme and SDH were significantly increased in different ESCU groups after chronic hypoxia,compared with control group with significant differences（P<0.05）.5.The effect of ESCU on the pathological change of myocardial and lung tissues after chronic hypoxia:the arrangement of myocardial and lung tissues in the ESCU groups were more regular.ESCU could obviously improve the pathological changes of myocardium and lung in experimental animals with chronic hypoxia,and reduce the infiltration of inflammatory cells.6.The effect of ESCU on AMPK-PGC-1αsignal pathway:ESCU could increase the expression of p-AMPK and PGC-1α,compared with the chronic hypoxia control group has significant differences（P<0.05）.Conclusions1.ESCU can prolong the survival time of acute hypoxia,also can extend the rotated-rod time and swimming time,and enhance the hypoxia-resistance in mice.2.ESCU can shorten the escape incubation period and swimming distance,improve the learning and memory ability after chronic hypoxia in mice.3.ESCU can reduce LDH and BUN levels,raise glycogen levels,improve the pathological damage of myocardial and lung tissues after chronic hypoxia,may be via AMPK-PGC-1αsignal pathway by increasing GLUT-4,SDH and Na⁺-K⁺-ATP enzyme activity,improve learning and memory after hypoxia.