Effects Of Different Doses Of Dexmedetomidine On Cerebral Ischemia-reperfusion In Rats

Objective Ischemic cerebral vascular disease (ICVD) is one of serious disease, its can damage the patients healthy,with high incidence, high mortality, and high disability rate. It’s found that DEX were shown to have neuroprotective effect in variety of animal models of cerebral ischemia, traumatic brain injury model and the application of neurosurgery operation. In this experiment, different doses of DEX were given before rats’unilateral middle cerebral artery occlusion. Neurologic outcome was evaluated after ischemia. Its’brains were removed for determination of cerebral infaret volume. Mean arterial blood pressure (MAP) were monitored. Arterial blood gases and plasma glucose concentration were analyzed. To investigate the effects of neurprotection by different doses of dexmedetomidine on cerebral iscemia-reperfusion in rats, and analyse its mechanism.Methods Fifty male SD rata weighing285±30g were randomly divided into5groups(n=10each):group B(normal saline ware intravenous infusions), group0.01A (0.01μg·kg-1·min-1DEX ware intravenous infusions),group0.1A(0.1ug·kg-1·min-1DEX ware intravenous infusions),group1A(1μg·kg-1·min-1DEX ware intravenous infusions),group10A(10μg·kg-1·min-1DEX ware intravenous infusions). Longa methods were used to establish the middle cerebral artery occlusion model, animals were treated with transient MCAO (tMCAO) for60min. Test drugs were infusion at15min before ischemia,and stop infusion at20min after reperfusion by femoral vein. Mean arterial blood pressure (MAP) were monitored every10mins. Arterial blood gases and plasma glucose concentration were analyzed before administration of saline or dexmedetomidine,5min before the onset of ischemia, and10,30, and60min after the end of ischemia. Neurologic outcome was evaluated starting24h after ischemia before the animals were sacrificed. The proportion of infarction size was evaluated by Image-Pro plus after stained by2,3,5-triphenyltetrazolium chloride(TTC).Results Compared with group B, neurologic deficit scores and the cerebral infaret volume were significantly decreased in groups0.01A、0.1A、1A (P<0.05). There were no significant difference between group B and group10A (P>0.05).The rats in the0.1A group exhibited a significant decrease in MAP as compared to group B. On the other hand, the group10A displayed a significant increase in MAP (P<0.05). Arterial blood gases were no significant difference among5groups (P>0.05). Compared with group B, plasma glucose concentration were significantly increased in group0.01A,0.1A,1A,10A5min before the onset of ischemia, and60min after the end of ischemia, and was up-regulated in a dose—ependent manner (P<0.05).Conclusion Intravenous pretreatment with0.01,0.1,1μg·kg-1·min-1dexmedetomidine can attenuate focal cerebral iscemia-reperfusion injury. Intravenous pretreatment with10μg·kg-1·min-1dexmedetomidine can not attenuate focal cerebral iscemia-reperfusion injury.