| Stroke is one of three leading causes of human death,and the treatment of stroke includes thrombolytic therapy and neuroprotective treatment.Nowadays,the treatment in clinic is limited,only the rt-PA is the most widely used while the time window is within 4.5 h and reperfusion injury is more serious than ischemia itself.Thus,there is an urgent need for developing some novel neuroprotective agents to meet the clinic need.Although there was reported that pretreatment with isosteviol has neuroprotective effects against ischemia reperfusion injury in rats with insufficient evaluation criterion,whether STVNa still has the same or better neuroprotective effects when the treatment start after the acute injury and the internal mechanism remain unknown.In our study,the research object is STVNa,an injectable sodium salt of isosteviol,which is more suitable for its clinical usage.We established transient middle cerebral artery occlusion(tMCAO)in rat and evaluate the neuroprotective effects of STVNa against ischemia reperfusion injury.And we used in vitro deprivation of oxygen and glucose cell model and LPS induced inflammation in microglial cell model to investigate the mechanism of STVNa.The main contents is as follows:1.After establishing a stable model of transient middle cerebral artery occlusion(tMCAO)in rat,we firstly focused on the dose-depended response of STVNa,and then early-stage explored the therapeutic time window and the protective effect against permanent middle cerebral artery occlusion(pMCAO).The results show that compared with vehicle group(P < 0.05),there are statistical improvement of cerebral infarction and neurological behavior in groups with intravenous infusion of STVNa 5?10?20 mg/kg after 1 h ischemia.Among them,the best dose was 10 mg/kg(P < 0.01),which could reduce the cerebral infarction nearly half.In the histological study,we found out that compared with vehicle group,10 mg/kg STVNa can significantly ameliorate the neuron injury and apoptosis after ischemia and reperfusion.What's more,10 mg/kg STVNa can even reduce brain edema and inhibit the increasement of permeability of blood brain barrier.In the therapeutic study,intravenous infusion of 10 mg/kg STVNa still showed neuroprotective effects after 6 h ischemia.And in permanent middle cerebral artery occlusion(pMCAO)study,compared with vehicle group,10 mg/kg STVNa can reduce the cerebral infarction and improve neurological behavior after 4 h occlusion.From the above,we can calculate the time window of STVNa is around 4~6 h after ischemia.2.Through in vitro deprivation of oxygen and glucose and reperfusion in SH-SY5 Y neuron cell,we study the neuroprotective mechanism of STVNa.The data showed that deprivation of oxygen and glucose for 10 h and then reperfusion for 24 h can significantly reduce cell viability of SH-SY5 Y,and 10 ?M STVNa can reverse the situation.By using Hoechst33342/PI double staining,after STVNa treatment,cell apoptosis can be inhibited and consistently,the production of anti-apoptosis factor BCL-2 increased,because of stabilization of the mitochondria membrane potential.Then,10 ?M STVNa can dramatically reduce the protein release and mRNA synthesis of NO?TNF-??IL-1? from LPS activated BV-2 microglial cell inflammation.Conclusion STVNa has neuroprotective effects against middle cerebral artery occlusion and the mechanism may involve,not only augment production of anti-apoptosis factor,protection of mitochondrial damage,but also inhibition of BV-2 microglial cell activated inflammation,relieve of brain edema and keep the blood brain barrier integrity. |
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