The Effect of Corpus Callosotomy in the Lithium-Pilocarpine Induced Status Epileptic Rats

Jeun, Sin Soo; Hong, Yung Gil; Park, Chun Kun; Kim, Mun Chan; Choi, Chang Rak; Kang, Joon Ki

Abstract

Section of the corpus callosum(SCC) is a useful surgical therapy in selected types of epilepsy, i.e., tonic, atonic, and intractable generalized convulsive seizures. The object of this study was to determine effect of SCC on behaviors, electroencephalography(EEG) and Fos expression in the lithium-pilocarpine model of status epilepticus in the rat. A total of 40 Sprague-Dawley rats were used. They were divided into two groups: control and lesioned group, 20 rats for each. The control group had no callosal section and was injected with lithium-pilocarpine. The lesioned group had callosal section before lithium-pilocarpine injection. In each group, ten rats were used for behavior and EEG monitoring and other 10 were used for Fos expression. The results were as follows: 1) In the SCC group, four(40%) rats never developed status epilepticus, among them two(20%) never exhibited any seizure, while all of the control group developed seizure and status epilepticus. None of the SCC animals died until 24 hours after lithium-pilocarpine injection but 70% of the control animals died within 24 hours of status epilepticus. This difference was statistically significant(p<0.05). 2) The mean latency to the first seizure, status epilepticus and periodic epileptiform discharges after lithium-pilocarpine injection were 34.7+/-2.6min, 32.3+/-1.8min and 180.4+/-9.8min, respectively, in the SCC group, while was 21.0+/-2.0min, 58.2+/-6.9min and 215.6+/-7.2min, respectively, in the control group. These latencies were significantly longer than in the control group(p<0.05). 3) There was a massive Fos expression on the cerebral cortex in the control group at 4 hours after lithiumpi-locarpine injection , while it was less in the SCC group. This difference was statistically significant(p<0.05). In conclusion, complete corpus callosotomy had contributed to the protective effect on the development of status epilepticus in the lithium-pilocarpine model which was similar to that observed in humans. And result of Fos expression suggest that Fos immunohistochemisty may be useful in the study of seizure pathways as a metabolic marker in the lithium-pilocarpine model.