The effect of low-frequency electrical stimulation on amygdala-kindled seizures in rat

Low-frequency stimulation (LFS) (<5 Hz) is a suitable approach for treating seizures caused by epilepsy. Different patterns of LFS have different effects on epileptic seizures. Since no LFS pattern has so far been determined to have the best efficacy in seizure quenching, this study investigated the effect of 60-min application of LFS on amygdala-kindled seizures in rat. In this experimental study, two groups of animals (14 rats) received twice-daily kindling stimulations after stereotactic surgery and a 1-week recovery period. In group 1 (n=6), fully kindled animals received daily kindling stimulations for four days, while in group 2 (n=8), kindled animals received LFS (1 Hz, 0.1 ms pulse duration, ½ afterdischarge threshold intensity) four times (in 24-hour intervals) exactly before kindling stimulations. Afterdischarge duration (ADD), stage 2 latency (S2L), stage 4 latency (S4L), and stage 5 duration (S5D) were recorded and compared with related control groups (the same animals that had received only kindling stimulation). Data was analyzed using repeated-measures ANOVA and post-hoc Tukey’s test for within-group comparisons and Student’s t-test for between-group comparisons. The first LFS application resulted in a significant increase of S2L and S4L by 91.5% (p<0.05) and 79.5% (p<0.01) compared with control group, respectively. Four-day consecutive LFS applications decreased S5D significantly, so that the first LFS application decreased S5D by 100% (p<0.001). In the first 2 days of LFS application, ADD decreased significantly by 46.9% and 40.4% (p<0.05), respectively, relative to control. The results suggest that LFS application immediately before seizure initiation has anticonvulsant effects.