The Neuroprotective Effect Of Mild Hypothermia And Expression Of Gabaar And NR2A On Hippocampus In Kainic Acid Induced Status Epilepticus In Rats

Part 1 The Neuroprotective Effect of Mild Hypothermia in Kainic Acid Induced Status Epilepticus in RatsObjective:To observe the antiepileptic role of mild hypothermia in Kainic acid induced status epilepticus and the cognitive impairment of rats.Meanwhile,to observe the antiepileptic effects of mild hypothermia and neuroprotective effect for hippocampal neurons.Methods:An animal model of status epilepticus（SE）was established in rats by intracerebroventricular injection of Kainic acid（KA）.We randomly divided 72 male SD rats into control group（group C）,SE model group（group SE）,mild hypothermia pretreatment group（group MP）,and mild hypothermia treatment group（group MT）.Mild hypothermia antiepileptic effect was evaluated by the seizure level in the course of kindling.The cognitive function of kindled rats was assessed by Morris water maze（MWM）test,and the role of mild hypothermia was detected.Using Nissal’s staining and HE staining observed neuroprotective effect for hippocampal neurons of kindled rats.Results:1 Typic seizure of status epilepticus was observed in SE group,MP group and MT group by intracerebroventricular injection of Kainic acid.The seizure level in MP group and MT group markedly decreased.No seizures occured in the control groups.2 In the Morris water maze,the escape latency of the rats in each group was detected,and（1）in first days and second days,there was no significant（P>0.05）between the groups,but the escape latency of SE and MP groups was prolonged compared with the control group.（2）Each escape latency in the 3^rd,4^th,5^th day are compared to the days of 1 and 2 have the tendency to reduce,the SE group as compared with the control group,the escape latency was significantly prolonged（P<0.05）;the escape latency of MP group was significantly shorter than that of SE group（P<0.05）,but it was longer than the control group（P<0.05）;the escape latency of MT group was compared with that of MP group（P>0.05）,but it was shorter（P<0.05）compared with SE group.3 Nissl staining and HE staining showed that:the nucleus of CA3neurons in the control group was clear and normal,and the cytoplasm was in the cytoplasm of the cells,and the cells arranged orderly and compact,no obvious neuronal loss;neurons of SE group were significantly reduced,the cell structure was disordered,the cell morphology was fixed,the number of the small body was significantly reduced,and the cell nucleus was not clear,and the chromatin aggregation;in the CA3 area of MP group and MT group neuron structure is regular,the shape is still normal,no neuron loss,the cell arranged in order,only a small amount of chromatin condensation,the body also has a marked increase in the body.Conclusions:In this study,the SE model of rat was established by intracerebroventricular injection of Kainic acid（KA）.Through the intervention of mild hypothermia treatment and mild hypothermia treatment,it was found that it had a certain anti epileptic effect;furthermore,it can prevent the degeneration and necrosis of hippocampal neurons,and improve the cognitive function of rats.Part 2 The Expression of GABA-AR mRNA,NR-2A mRNA on Hippocampus in Kainic Acid Induced Status Epilepticus in Rats Treated with Mild HypothermiaObjective:To observe the role of mild hypothermia on expression of GABA-AR mRNA,NR-2A mRNA in Kainic acid induced status epilepticus,and to explore the mechanism of brain.Methods:SE model was established in SD rats by intracerebroventricular injection of Kainic acid（KA）.Using random number table method 144 male SD rats were divided into 4 groups（n=36）,respectively:control group（Group C）,SE model group（group SE）,mild hypothermia pretreatment group（group MP）,and mild hypothermia treatment group（MT group）.Each group was further divided into three subgroups（6h,12h and 24h after SE,n=12）,12 rats of each subgroup.In situ hybridization was used to detect the expression changes of GABA-AR mRNA and NR-2A mRNA in CA3 area.Results:The degree of seizure and neuronal damage of rats in group MP and group MT were lower than those in group SE.In hippocampal tissue,GABA-A RmRNA decreased,while NR2A mRNA expression in group SE increased significantly than those in group C（P<0.05）;expressions of GABA-AR mRNA in group MP and group MT increased significantly,while expressions of NR2A mRNA decreased（P<0.05）.Conclusions:Mild hypothermia intervention can increase the expression of NR-2A and down regulate the expression of GABA-AR in rats,which may be the mechanism of its anti-epilepsy and neural protective effect.