| Objective Stimulate Sprague-Dawley Rat Insular to establish chronic Epilepsy Model. we try to visualize the characters of spontaneous repeated relapse and tissular changes and study the dynamic changes in the expression of Arc, GAP-43 and P38 in the hippocampus circuits of rats during chronic periods atfer their established chronic Epilepsy Model, to systematically study their effects on mossy fiber sprouting and synaptic reorganization and their role in synaptic plasticity in Epilepsy and to investigate possible nosogenesis of Insular Epilepsy.Methods 1. Establishment of Rat insular chronic Epilepsy Model and pathological observation: 48 male Sprague-Dawley Rats are divided into 4 groups randomly: Insular kindling group (IK), Amygdale kindling group (IK), Insular , amygdale simultaneously kindling group (BK) and normal control group. No electrodes were implanted into normal control group. Bipolar electrodes were implanted into left Insular or left Amygdale or both and rats 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. The hippocampal morphology was observed with Hematoxylin and Eosin (HE) colouration, Nissl colouration and Timm colouration. 2. The study of expression of Arc,GAP-43 and P38 on synaptic plasticity in hippocampus of insular epilepsy rats: 72 male adult rats, were divided in to insular Kindled group and Sham group randomly. Each group had 36, they was divided into 1,3,7,15,30 and 60d sub-groups(n=6) respectively.After kindled, with immunohistochemistry staining and hybridization in situ method to explore the change of Arc, GAP-43 and P38 expression in hippocampus of insular electrical kindled epilepsy rats.Results 1.Chronic Epilepsy Model is succeeded by Stimulating Sprague-Dawley Rat Insular. There is significant difference in the aftercharge threshold between Insular and Amygdale kindling groups (P<0.05). There is significant deviation at kindling speed in three groups: IK is the most rapid kindling group and BK group was kindled more slowly (p<0.05). There is no significant difference in kindling rate between three groups. Nissl staining showed a large number of dense pyramidal cells and granule cells were most prevalent in hilar region of dentate gyrus and in hippocampal subfields CA3 and CA1 in normal control group. Neuronal cells arranged in neat rows, form is complete and Nissl body is rich in cytoplasm. In insular kindling group (IK), Amygdale kindling group (IK), Insular, amygdale simultaneously kindling group (BK), the pyramidal cells and granule cells in hippocampal subfields and dentate gyrus are incomplete, part of the cell swelling, rupture and disordered.Nissl body is reduction in cytoplasm. Timm staining showed mossy fiber sprouting in dentate gyrus granule cells within the molecular layer were observed after 4 weeks in Insular kindling group (IK), Amygdale kindling group (IK), Insular, amygdale simultaneously kindling group (BK), and in this layer gradually formed a dense band. 2. It is no significant difference to Arc mRNA and protein expression at hippocampus CA1 and CA3 pyramidal layer between Kindled group and Sham group.hybridization signals and immunostaining are very weak and close to the background staining level. Epilepsy day 1: GAP-43 mRNA and protein expression at hippocampus dentate gyrus granular cell layer, hilus and CA3 pyramidal layer in kindled group were higher than the sham group(P<0.05). The expression of those declined in epilepsy day 3(P>0.05). Expression increased again at epilepsy day 7 and were significantly higher than the sham group at epilepsy day 15 and 30(P<0.05). There is no statistically difference between two groups at epilepsy day 60(P>0.05). Expression of P38 mRNA and protein: hybridization signal and immunostaining at hippocampus dentate gyrus granular cell layer, hilus and CA3 pyramidal layer began to increase at epilepsy day 7 and reached peak at epilepsy day 15(P<0.01), which lasted 4 weeks and then began to decline.Conclusions 1. Insular is an area that causes epilepsy symptom is proved by Chronic Epilepsy Model are succeeded by Stimulating Sprague-Dawley Rat Insular.Itself has the potential caused by epilepsy. 2. Insular kindling model induced hippocampal mossy fiber sprouting can be proved close relationship of Insular Epilepsy, the hippocampus plays an important role to occurrence and maintenance of Insular Epilepsy 3. Arc, GAP-43 and P38mRNA and protein in the insula may be involved in synaptic plasticity changes in epilepsy and the key molecular mechanism of synaptic plasticity. |
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