Neuroprotective Effect Of Total Flavonoids From Lycium Barbarum Leaves Against Cerebral Ischemia/Reperfusion Injury In Mice

Aim: To observe neuroprotective effect of total flavonoids from Lycium barbarum leaves against cerebral ischemia/reperfusion ingury in mice and investigate its relating mechnisms from antioxidant activity and affect atpase activity.Method: 60 male kunming mice（postnatal 2months） were randomly divided into six groups, sham-operated, model, cordycepin low dose（30mg/kg）, middle dose（100mg/ kg）, high dose（300mg/kg） and nimodiping groups（20mg/kg）. The mice in total flavonoids from Lycium barbarum leaves-treated groups and in nimodiping group were administered with total flavonoids extract（30mg/kg, 100mg/kg, 300mg/kg） and nimodiping（20mg/kg） orally once a day for two weeks before operation respectively, whereas the sham and ischemia/reperfusion group were given same amount of double distilled water（0.1ml/10 g body weight）. After transient cerebral global ischemia for 15 minutes and 24 hours reperfusion period, the mice were deeply anesthetized and decapitated. Brains were quickly removed to calculated brain index, and then bake to constant weight in 110℃ for calculating the brain water content. SOD activity, the level of MDA, Na⁺-K⁺-ATPase and Ca²⁺-ATPase were detected by kits. Morphological changes in the cerebral cortex and hippocampus CA1 area were observed by HE staining.Results:1. Effect of total flavonoids from Lycium barbarum leaves on brain index and brain water content in ischemia/reperfusion mice was that high dose of total flavonoids extracts can effectively reduce the mice brain index and cerebral water content in ischemia/reperfusion mice（compared with model group）.2. Effect of total flavonoids from Lycium barbarum leaves on SOD activity and MDA level in ischemia/reperfusion mice was that the activity of SOD and the level of MDA were 110±3.9Uml and 6.1±0.4nmol/ml in sham-operated group, respectively. Ischemia/reperfusion group resulted in a significant decrease in SOD activity（down to 99.7±4.1Uml, compared with sham-operated group） and marked increase in MDA level（up to 9.9±0.9 nmol/ml, compared with sham-operated group）. High dose of total flavonoids extract pretreatment can significantly reduce the peroxidative degree of lipid, obviously improve the SOD activity（compared with model group, P < 0.05, n = 10）, and reduce the MDA level in the brain（compared with model group, P < 0.05, n = 10）.3. Effect of total flavonoids from Lycium barbarum leaves on the level of Na⁺-K⁺-ATPase and Ca²⁺-ATPase in ischemia/reperfusion mice was that the activity of Na⁺-K⁺-ATPase and Ca²⁺-ATPase were 1.77±0.50μmol/mgprot/h and 1.85±0.47μmol/mgprot/h in sham-operated group, respectively. Ischemia/reperfusion group resulted in a significant decrease in the activity of Na⁺-K⁺-ATPase（up to 1.07±0.30μmol/mgprot/h, compared with sham-operated group） and marked decrease in the activity of Ca²⁺-ATPase（up to 1.16±0.27μmol/mgprot/h, compared with shamoperated group）. High dose of total flavonoids extract pretreatment can significantly inhibite the activity of Na⁺-K⁺-ATPase and Ca²⁺-ATPase decline（compared with model group, P < 0.05, n = 10）.4. Effect of total flavonoids from Lycium barbarum leaves on morphologic changes in ischemic regions of cortex and hippocampus were that mice with ligation of bilateral common carotid artery（2 vo） ischemia 15 minutes and reperfusion 24 hours, can be found in model group of mice with cerebral cortex and hippocampus especially in hippocampal CA1 region neurons have obvious damage through HE stain, such as nucleus pyknosis, nucleus disappear, neurons disappear and so on. Total flavonoids from Lycium barbarum leaves pretreated can markedly reduce these pathological changes and attenuate ischemia/reperfusion-induced cell loss in the cortex and the hippocampal CA1 area.Conclusion: The total flavonoids from Lycium barbarum leaves had protective effect of cerebral ischemia, and can efffectively alleviate neuronal injury. The mechanism of neuroprotective effect of the total flavonoids extract may be related to improve the body resistance to oxidative stress, protect ATPase activity and improve the ion transport in the brain.