Influence Of Diazoxide On The Expression Of NR1 After Deep Hypothermic Brain Ischemia/reperfusion In Rats

Objective:To study diazoxide on the expression of NR1 after deephypothermic brain ischemia/reperfusion in rats and discuss themechanism of brain protect for diazoxide.Methods:PartⅠ: animal experiment: the healthy SD rats, after anaesthesia,blood flow of bilateral common carotid artery of rats were occludedabout 60 minutes when its temperture was reduced to (21±1)℃by ice,then normal temperature were resumed.PartⅡ: Influence of diazoxide on the expression of NR1 afterdeep hypothermic brain ischemia/reperfusion in rats. The rats weredivided randomly into three groups: Sham group;Diazoxide treatmentgroup and model group. Each group included by 60 minutes occlusionfollowed reperfusion of bilateral common carotid artery for 2h, 6h, 12hand 1d, 2d, 3d and 7d sub groups. To observe pathology of brain andexpression of NR1 by the techonlogy of immunohistochemistry.PartⅢ: Influence of diazoxide on the expression of NR1 mRNAafter deep hypothermic brain ischemia/reperfusion in rats. The rats weredivided randomly into three groups: Sham group; Diazoxide treatmentgroup and model group. Each group included by 60 minutes occlusionfollowed reperfusion of bilateral common carotid artery for 2h, 6h, 12hand 1d, 2d, 3d sub groups. To observe brain moisture capacity,electron microscope of brain and measured the expression of NR1 mRNA in different time points with RT-PCR.Data were analyzed by software SPSS 11.0.Results:1. result of brain moisture capacity: brain moisture capacity of shamgroup was obviously lower than diazoxide group and model group,diazoxide group was lower than model group, It steped up at 12h,reached peak at 24h,and gradually come back to normal level at 3d indiazoxide group and model group.2. result of brain pathology: with ilight microscope, model grouphad obvious schemic change, to display tissue looseness, caryonpyknosis, nucleolus disappear, endochylema looseness, superficialdyeing, cavitation in endochylema and around blood vessel. Sham groupis clear with framework of tissue, existence with nucleolus, had nochange of pathology. Diazoxide group's cell was a little oncotic,mucleolus was exist.3. result of electron microscope: The three groups had no obviousdifference on ultramicrostructure of brain after 60 minutes occlusionfollowed reperfusion for 6h, glia cell of model group had apoptosistendency, but wasn't apoptosis, and chondriosome wasn't oncotic.4. result of immunohistochemistry: The expressions of NR 1 wasincreased at 2h, reached peak at 1d,and gradually come back to normallevel at 7d in diazoxide group and model group. However,Preconditioning with diazoxide resulted in a significant reduction in the expressions of NR1 at 2, 6, 12h and 1d, 2d comparing with Modelgroup. The expressions of NR1 of the both group were increased thansham group.5. result of RT-PCR: The expression of NR1mRNA was at low levelin sham group, it was increased at 2h, reached peak at 1d, and graduallydown,the three groups were no obvious difference at 7d.Conclusion: Preconditioning with diazoxide on deep hypothermicbrain ischemia/reperfusion rats have the effect of brain protection, themechanism of brain protection is maybe down regulation the expressionof NR1.