The Effect Of Acute Epileptic Seizure Induced By PTZ On The Expression Of F-actin, Calponin3and ROCK2in The Rat’s Cerebral Neurons

Objective：We detected the effect of acute epileptic seizure induced by pentetrazol(PTZ) on the expression of F-actin, Calponin3, ROCK2and phosphorylatedROCK2in the rat’s cerebral neurons, in order to illuminate the possiblemechanism to prevent the F-actin from abnormal depolymerization and totrigger the rearrangement of F-actin.Methods：3-week-old immature rats were divided into control and epilepsy groups.We judged if the acute epileptic seizure model has been set sucessefully or notaccording to the changes about rat’s behaviour and EGG after administrationof PTZ60mg/kg ip. After the acute epileptic seizure model was set, the animalsof epilepsy group were subdivided into4groups:1d,2d,3d and7d accordingthe time after the acute seizure. Then, the rats were sacrificed at different timepoints respectively. The cytoskeleton, F-actin, in the cerebral neurons of ratswas stained using phalloidine labeled by Alexa-488. The distribution ofCalponin3and ROCK2in the cerebral neurons was detected byimmunofluorescence. The expression level of Calponin3, ROCK2and phosp-horylated ROCK2was analyzed by Western blot. Results：1. After administration of PTZ60mg/kg ip, the changes of immaturedrat’s behaviour reached to4to5level according to Racine’ scale，EEGshowed various epileptic waves.2. Compared to the control, the fluorescence intensity of F-actin in thehippocampal inner molecular layer of the epileptic immature rats, where thedendritic spines are concentrated, was lowered (P<0.05), and the dot-shapedaggregation of F-actin disappeared one day after acute seizure.3. The immunofluorescence results that Calponin3dispersed in thecytoplasm of neurons of control group. However, it aggregated in the cell cortex（thin layer of cytoplasm immediately deep to the cytomembrane）of neuronsin7d after acute seizure. And ROCK2was located in a small amount of neuritisin control, whereas a great quantity of ROCK2was found in both of the cellbody and neuritis in7d after acute seizure.4. The Western blot showed that the expression level of Calponin3wasmarkedly decreased in different time points after acute seizure compared to thecontrol (P<0.05). However, it was enhanced gradually with the extended timeand tended to the normal within1week. The expression level of ROCK2beganto increase from3d to7d steadily compared to control (P<0.05). However, thelevel of phosphorylated ROCK2was enhanced from1d to7d sustainablelycompared to control (P<0.05) and decreased gradually with the extended time. Conclusions：The acute epileptic seizure model has been set sucessefully afteradministration of PTZ60mg/kg ip.The acute epileptic seizure in the immature rats induced by PTZ not onlyleads to the abnormal depolymerization of F-actin, but also actives theRhoA/ROCK2signal pathway simultaneously and up-regulates the expressionof ROCK2and Calponin3. It is a possible mechanism to prevent the furtherdepolymerization of F-actin and promotes the rearrangement of F-actin throughthe phosphorylation of Calponin3depending on RhoA/ROCK2signal pathway.