| Objectives:Epilepsy has been a common clinical syndrome of functional disorder,which is essentially an abnormality of cerebral function on account of the discharges of some cerebral neuron in over high excitement state.However, the mechanics of epilepsy is not known yet.Epilepsy can lead to brain indured.Apoptosis or programmed cell death resulting from a series of complicate protease enzyme cascade,is an important pathway of brain injured casuing by epilepsy.As we all know,long time seizu- re can lead to cell apoptosis,necrosis of neuron and sclerosis of hippocamps. Rats were kindled by PTZ,and then contributed to status epilepticus (SE).The changes of behavior were observed after seizure and the situation of neurocyte loss or necrosis and mossy fiber budding were determined with Nissl staining and Timm staining,respectively. Meanwhile, ultramicrostructure of hippocamp CA3 area was observed with electron microscope method.The average optical density of positive cell was counted with immunohistochemistry. Besides, exp -ressions of caspase3 and hsp70 in hippocamp of rats were determined by me- ans of Western blot. To investigate the dynamic state changes of caspases3 and hsp70 in hippocamp of rats after seizure ,thus we can adopt intervention and control neurocyte apoptosis in time.What's more,we can explore a new method to lessen the brain damaged of epilepsy by means of molecular level.Methods: Choosing status epilepticus(SE) model by PTZ-induced thro- ugh intraperitoneal injection,70 mature male Sprague-Dawley(SD) rats(weight 180±20g) were separated into two big groups randomly:status epilepticus group and normal control group.In addition.Each SE group is divided into 3h,6h,12h and 24h subset groups,and each group includes14 rats. Rats were injected by PTZ 40mg/kg, 20mg/kg after 10 mins,10mg/ kg after 10 mins. According to Racine criterion,seizure intensity was divided into 6 grades: grade 0:any seizure was not observe;grade , a little tingling of beards and twitching face; gradeⅡ,nodding,chewing accompanying with twitching face or tail; gradeⅢ, raising one of a forelimb and clonus;gradeⅣ,standing acco- mpanying with bilateral forelimbs;gradeⅤ: standing accompanying with fall -ing down,generalized tonic-clonic seizure. The kindled standard is that seizur -es of gradeⅣand gradeⅤcan be observed successively,which can last for above 30 mins. The changes of behavior were observed after seizure, and the average optical density of positive cell was counted with immunohistochemi -stry. In addition,the situation of neurocyte loss or necrosis and mossy fiber budding were determined with Nissl staining and Timm staining, respectively .Meanwhile, ultramicrostructure of hippocamp CA3 was observed by means of electron microscope . Expressions of caspase3 and hsp70 in hippocamp of rats were determined by Western blot method.Results: 1 Results of epilepticus model:SE group using 70 rats effectively, 11 rats use 40mg/kg, 14 use 50mg/ kg,15 use 60mg/ kg,18 use 70mg/ kg, 8 use 80mg/ kg, 4 use 90mg/ kg,they began to nod,wash face and twitching face or tail.Accompanied by injecting every 10 mins,their muscles began to clonus, then forelimbs began to uplift and tonic clonic seizure at last. However, NC group rats did not appear epileptic seizure.2 Changes of histology in hippocampus2.1 Nissl staining: In hippocampal CA1 area of the rats in SE group , there was the following apoptosis changes: shrinkage of neuron, anachromasis of nucleus,karyokinesis and karyolysis. Besides,most of kytoplasm appears vacuolus and disorder of arrangement,nissl body diminished,fract lost of neuron .This change is the most obvious in 24h,while the neuron was damaged slightly in 3h . In hippocampal CA1 area of the rats in NC group,there were intact neurous, light staining of nucleus ,distinct structure and affluent kytopla -sm,and the morphous of nissl body are similar to normal.2.2 Timm staining: In hippocampal CA3 area of SE subset groups and NC group ,the score of mossy fiber budding are merely 0 to 1 score .2.3 Observation of ultramicrostructure in hippocampal CA3: In hippocampal CA3 area of the rats in SE groups , a series of changes are as follows: obscure boundary of karyolemma and emboly at times,chromatin with edge, diminished the quantity of mitochondria or swellen outline. The changes are the most obvious in 24h,while the changes are slight in 3h .As for the NC group ,appearing distinct boundary of karyolemma,intact mitochondria and organelles.3 Changes of caspase3 and hsp70 in hippocampus:The expression of caspase3 and hsp70 began to increase after 3h in SE group,and then increased the highest in 24h(P <0.01 compared with NC group).Obviously, the rate of positive cells have a tendency to heighten with prolong of time. The cells of caspase3 and hsp70 can be scattered seen in the kytoplasm of hippocampus in NC group.4 The expression of caspase3 and hsp70 protein in hippocampus:The expression of caspase3 and hsp70 protein began to increase slightly at 3h after seizure and at 24 h after seizure significantly(P <0.05 compared with NC group).There is a small amount of caspase3 and hsp70 protein in NC group.Conclusion: 1 PTZ provides an effective model of postseizure dysfunc- tioning by intraperitoneal injection,which is similar to human being of tonic clonic seizure.2 Although there are different morphology changes of brain tissue during acute seizure, yet there are not appear evident changes of mossy fiber budding in 24h,which indicates that the memory functions of rats have not been influen -ced obviously.If some effective measures can be taken,the damages of brain tissue can be reversed in time.3 Seizure can lead to neurocyte apoptosis and upregulate expression of caspase3 and hsp70 simultaneously. The result demonstrates that neurocyte apoptosis at acute stage of seizure might play an important role in stress defen -dence of brian tissue.
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