The Expression Of Activity-regulated Cytoskeletal-associated Protein In The Hippocampus Induced By The Insular Epilepsy Rats

Objective Stimulate Sprague-Dawley Rat granular insular cortex to establish chronic Epilepsy Model. we try to visualize study the expression of Arc in the hippocampus,to investigate the expression of Arc in insular epilepsy and to investigate possible nosogenesis of insular epilepsy.Methods 1. Establishment of Rat insular chronic Epilepsy Model: 40 male Sprague-Dawley Rats are divided into 2 groups randomly: kindling group and sham-operated group.35 rats in kindling group ,and 5 rats in sham-operated group.Bipolar electrodes were implanted into left granular insular cortex,and kindling group were stimulated at 1.5 times of after discharge threshold twice daily to establish chronic Epilepsy Model. Stimulus train consisted of 1-ms (square biphasic) pulses at 60 Hz, with train duration of 1s. Sham-operated group use the same method to the kindled group without electrical stimulation. Another stimulus of the same intensity was used after a month to see the stabilization of the model2.The expression of Arc in the kindling model: male adult rats, were divided in to insular Kindled group , Sham-operated group , a single electrical stimulated group and control group randomly.In addition to the control group(n=7) ,the other in each group is divided into 3h,6h sub-groups(n=7). Bipolar electrodes were implanted into left granular insular cortex,and kindling group were stimulated at 1.5 times of afterdischarge threshold twice daily to establish chronic Epilepsy Model. Stimulus train consisted of 1-ms (square biphasic) pulses at 60 Hz, with train duration of 1s. Sham-operated group use the same method to the kindled group without electrical stimulation. A single electrical stimulated group: use the same method to the kindled group with only twice electrical stimulation. Rats were killed painless,with immunohistochemistry staining,RT-PCR,hybridization in situ and Western blotting method to explore the change of Arc expression in hippocampus of insular electrical kindled epilepsy rats.Results 1. Chronic Epilepsy Model is succeeded by Stimulating Sprague-Dawley Rat left granular insular cortex. Electrode falled from one of them ,3 electrodes were not accurate implanted in left granular insular cortex,and remaining 31 rats were kindled successfully,which rate 88.6%(31/35).In a quiet state, low frequency of EEG in normal rats,with 10Hz, low frequency,energy is also low,whenⅤgrade the frequency of EEG increased attack to 30 Hz,and energy is greatly enhanced. The rats can reachⅣ～Ⅴgrade throgh a period of kindling, Another stimulus of the same intensity was used after a month that can reachⅤgrade.2.Arc mRNA and protein exist in the hippocampus of the normal rat,at 3 h after kindled, Arc mRNA and protein staining were already significantly increased in hippocampus and the dendritic field (molecular layer) of the dentate gyrus(P<0.01); at 6 h after kindled ,the expression of Arc protein in hippocampus and dentate gyrus is significantly higher(P<0.01),but the expression of Arc mRNA in hippocampus and dentate gyrus has been reduced to normal(P>0.05).Compared with the control group, the expression of Arc mRNA and protein are no significant difference(P>0.05) in a single electrical stimulated group and sham-operated group .Conclusions Insular Epilepsy and hippocampus, could have close relationship.Arc may play an important role in Insular Epilepsy; Arc may be involved in synaptic plasticity changes in insular epilepsy and the key molecular mechanism of synaptic plasticity.