The effects of electric cortical stimulation on the cortical excitability in the epileptic rats

Abstract

Objective To study the effects of repetitive electric cortical stimulation on the cortical excitability in the chronic epileptic rats induced by ferric chloride. Methods The chronic epileptic rats induced by intracortical injection of ferric chloride solution in the sensorimotor area were used. So we studied the effects of the low frequency (1 Hz) low amplitude (0.1 mA)and low frequency (1 Hz)high amplitude (1.0 mA)and high frequency(100 Hz)low amplitude(0.1 mA)and high frequency(100 Hz)high amplitude(1.0 mA)electric cortical stimulation on the cortical excitability by investigated the threshold and duration of cortical after discharge and the behavior score in the chronic epileptic rat. At the same time rats were treated with the sham-stimulation as control group. Results After 1 Hz and 0.1 mA repetitive electric cortical stimulation in 5 d, the cortical afterdischarge threshold (2.10 ±0.38)mA significantly ascended compared with that of the control group (1.5 ±0.33) mA, P ＜ 0.05. There was no statistic difference of behavior score and duration of cortical afterdischarge after repetitive electric cortical stimulation in 5 d compared with that of the control group. The ratio of behavior score and cortical afterdischarge threshold after 1 Hz and 0. 1 mA (1.88 ±0.60) or 1 Hz and 1.0 mA (2.18 ±0.38) repetitive electric cortical stimulation in 5 d was significantly lower than that of the control group (3.22 ±0.67, P ＜0.01 and P ＜0.05, respectively). Conclusion After the repetitive low frequency(1 Hz)low amplitude (0.1 mA)electric cortical stimulation the cortical afterdischarge threshold significantly ascended in the chronic epileptic rat induced by intracortical injection of ferric chloride solution. It means the depression of cortical excitability. The results of this study showed that electric cortical stimulation with suitable parameter can produce a suppressive effect on the epileptic rat induced by intracortical injection of ferric chloride solution. Key words: Epilepsy; Electric stimulation; Cerebral coretex; Models,animal; Rat