| Accounting for 80% of all CVDs (cerebrovascular diseases), ICVD (Ischemic cerebrovascular disease) has elbowed cardiopathy and cancer aside to become the top fatal disease in China. The disease featured by higher morbidity, disability rate, and case fatality rate has been a major clinical risk factors, which has attracted much attention. Common mechanisms of ICVD include EAA (excitatory amino acid)poisoning, free radical damages,Calcium ion overload, inflammation and apoptosis. However, it is not all that clear how these influencing factors work in different pathophysiological links and how they work interactively. Dihydromyricetin (DMY) is the major flavone that is found in Ampelopsis grossedentata grown widly in the south China. A number of studies showed that the parmacological effects of DMY were numerous.Our early study has indicated that DMY(500mg·g-1) has protective effect against I/R (ischemia-reperfusion) injury, which might be involved to its anti-oxidant activities.The aim of this research was to set up a mice MCAO/R(middle cerebral artery occlusion/reperfusion) model and investigate the anti-inflammatory and anti-apoptotic mechanisms of DMY’s protective effect against I/R injury in mice. It can provide a theoretical and experimental foundation for the uses of DMY on the treatment of CVDs.PART I EFFECT OF DIHYDROMYRICETIN ON CEREBRAL ISCHEMIA-REPERFUSION INJURY INDUCED INFLAMMATORY REACTION IN MICEObjective To observe the influences of DMY on inflammatory response and 5-LOX after I/R injuries in MACO mice.Methods Male Kunming mice were randomly divided into three group, namely the sham control group,I/R group and DMY (500mg·kg-1) group. Mice model of middle cerebral artery occlusion (MCAO,3h)/reperfusion (24h) model was established by the improved intraluminal filament technique. Daily intragastric administration of DMY was carried out 10 days before the surgery, with one extra dosage 1h before ischemia and 12h after reperfusion respectively. Mice brains were removed 24h after reperfusion. The expressions of IB A1 (ionized calcium binding adaptor molecule-1), a marker of microglia, and 5-LOX were detected by immunohistochemistry.The expression of 5-LOX mRNA was determined by real-time PCR, and ELISA was used to determine the quantities of inflammatory fator TNF-a, and LTB4(leukotrienes B4), CysLTs (cysteinyl leukotrienes),the metabolites of 5-LOX, in the homogenate of ischemic brain tissue.Results Compared with the I/R model group, DMY(500mg·kg-1) could obviously inhibit the activation of microglia and the production of LTB4 and CysLTs (P<0.05 or P<0.01), and lower the level of TNF-a and the mRNA and protein expression of 5-LOX as well.Conclusion DMY can ameliorate focal I/R injury-induced inflammatory response, which is probably through its inhibition on 5-LOX.PART IIEFFECT OF DIHYDROMYRICETIN ON CEREBRAL ISCHEMIA-REPERFUSION INJURY INDUCED APOPTOSIS IN MICEObjective To study DMY’s anti-apoptosis effect by observing the changes of neuronal apoptosis and the expression of Bax and Bcl-2 in I/R mice.Methods Mouse MCAO/R model was prepared by using an intraluminal filament technique and mice were randomly divided into three groups, namely the model group, sham control group, and DMY (500mg·kg-1) group. The same dispose as specified in Part I were applied to these mice. Brains were removed after 24h reperfusion, and then the positive apoptotic cells were numerated by TUNEL staining; and the protein and mRNA expression of Bax/Bcl-2 were detected by immunohistochemistry and real-time Fluorescence quantitative PCR respectively.Results DMY could significantly decrease the number of TUNEL-positive cells(P< 0.05, DMY vs I/R model) in ischemic brain tissue, up-regulate the protein and mRNA expression of Bcl-2 while down-regulate the expression of Bax.Conclusion DMY can ameliorate focal I/R injury-induced neuronal apoptosis,and the mechanism could be partly ascribed to up-regulate expression of Bcl-2 while down-regulate the expression of Bax. |
PDF Full Text Request