Establishment Of Focal Cerebral Ischemia-reperfusion Injury Model In Mice And Intervening Effects Of Dihydromyricetin

Cerebral ischemia-reperfusion injury (IRI) is a complicatedpathophisiological process involving various pathogenic factors, of whichmechanism remains partially unraveled.Ischemia cerebrovascular disease(ICVD)has been issuing an increasingly grave threat to humane health. The regulartreatments to ICVD, however, leave much to be desired,with dissatisfactoryefficacy yet severe side effects.Thus is the urgency prosposed,to thedevelopment of new drugs with higher selectivity and lower toxicity.The present study ameliorates the existing methods to molding focalischemia-reperfusion injury model in mice and illuminates the protective effectDMY to IRI,which has been verified associated with DMY’s antioxidantpotency. This research is supposed to lay the foundation of a valid animal modeland data support for clinical application of DMY in ICVD patients anddevelopment of new anti-ICVD drugs with higher selectivity and lower toxicity. PART IESTABLISHMENT AND EVALUATION OF FOCALCEREBRAL ISCHEMIA-REPERFUSION INJURY MODEL INMICEObjective: To establish and evaluate the focal cerebralischemia-reperfusion (I/R) injury model in mice.Methods：Sixty male Kunming mice were randomly divided into shamgroup (n=30) and I/R group (n=30).The middle cerebral arteryocclusion/reperfusion (MCAO/R) model was established by the improvedintraluminal filament technique in mice. The reliability of the model wasevaluated by the neurologic deficit score, cerebral infarction rate, brain watercontent, and brain histopathological change.Results：The survival rate and total success rate of the model was83.33%and76.67％respectively. In the sham group, the neurologic deficit scorewas(0±0), the cerebral infarction rate was(0±0)％, and the brain water contentwas(77.29±0.45)%. In the I/R group, the neurologic deficit scorewas(2.42±0.53), the cerebral infarction rate was (23.03±3.42)％, and the brainwater content was(83.18±2.35)%. the neurologic deficit score was(2.42±0.53),the cerebral infarction rate was (23.03±3.42)％.Compared with the sham group,the neurologic deficit score, cerebral infarction rate and brain water content inthe I/R group were all markedly increased (P<0.01).At the same time, the typicalpathological change of cerebral infarction was also observed in the I/R group. Conclusion：The simple and reliable focal cerebral I/R model in mice has beensuccessfully established.PART IIPROTECTIVE EFFECTS OF DIHYDROMYRICETIN ONFOCAL CEREBRAL ISCHEMIA-REPUFUSION INJURY INMICEObjective：To study the protective effects of dihydromyricetin (DMY) onfocal cerebral ischemia-reperfusion (I/R) injury in mice.Methods：Mice model of focal cerebral I/R injury was established bymiddle cerebral artery occlusion (MCAO) method, ischemia3h and reperfusion24h. Kunming mice were randomly divided into4groups: sham control group,ischemia-reperfusion group, low-dose and high-dose DMY group (250,500mg kg-1).The behavior score, the cerebral infarction rate and brain water contentwere measured. The histopathological change of brain and the numbers ofneurons in ischemic penumbra area were observed.Results：Compared with ischemia-reperfusion group,500mg kg-1DMYcould obviously lower（P<0.05or P<0.01） the behavior score, cerebralinfarction rate and brain water content, and improve histopathological injury，increase the numbers of neurons in ischemic penumbra area，while cerebralinfarction rate decline （P<0.05)was only observed in250mg kg-1DMY group.Conclusion：DMY has protective effect and antioxidant potency on focalcerebral ischemia-reperfusion injury. PART IIIMECHANISM STUDY OF PROTECTIVE EFFECT OFDIHYDROMYRICETIN AS AN ANTIOXIDANT ON FOCALISCHEMIA-REPERFUSION INJURY IN MICEObjective：To study the protective effects of dihydromyricetin (DMY) asan antioxidant on focal cerebral ischemia-reperfusion (I/R) injury in mice.Method:40male Kunming mice were randomly divided into4groups:sham control group, ischemia-reperfusion group, low-dose and high-dose group(250,500mg kg-1). The MCAO procedure and DMY administration werethen performed exactly the same way as mentioned in Part II. The cerebrallevels of MDA, t-SOD and GSH-Px on24h-reperfusion were determinedrespectively in every group after the mice had been sacrificed.Results：Compared with ischemia-reperfusion group, significantly higher(P<0.01） levels of t-SOD and GSH-Px were observed after high dosageDMY(of500mg kg-1)treatment along with evidently lower levels(P <0.01）ofMDA.Conclusion: DMY has a protective effect as an antioxidant on focalcerebral ischemia-reperfusion injury in mice.