Effect of low frequency electrical stimulation of dentate gyrus on amygdala kindling acquisition in rats

Low frequency stimulation (LFS) has been recently suggested as an antiepileptic method in treating the drug-resistant epileptic syndromes such as temporal lobe epilepsy. So far، in the most clinical and experimental studies، LFS has been applied to the seizure focus itself. Considering the role of dentate gyrus in spreading of the limbic seizures، in the present study the effect of LFS of dentate gyrus on amygdala kindling-induced seizures was investigated. To kindle the animals، using stereotaxic instrument، a tripolar electrode was inserted into right basolateral area of amygdala and a bipolar electrode was ipsilaterally placed in dentate gyrus of male Wistar rats. After a 10 days recovery period، animals divided into two groups. The animals of kindled group were received daily electrical stimulations. In kindled+LFS group، LFS was delivered to dentate gyrus 1 min after cessation of amygdala kindling stimulation. The maximum seizure stage and duration of afterdischarges were evaluated after kindling stimulation. The effect of LFS on behavioral seizure stages and afterdischarges was compared using Kruskall Wallis and repeated measures 2-way AVOVA. A P value less than 0. 05 was considered as significant level. The required time to achieve a stage 5 seizure was 12 days in kindled group animals. However، animals of kindled+LFS group did not show more than stage 2 seizure following 12 days of stimulation. LFS of dentate gyrus significantly prevented the increment of behavioral seizure stages and afterdischarge duration in kindled-LFS group compared with kindled group. The results of this study demonstrated that application of LFS in the dentate gyrus can be an effective therapeutic method for controlling the amygdala kindling-induced seizures. Furthermore، this study provide further evidences showing LFS of brain areas involved in spreading the seizures، other than seizure focus can have anticonvulsant affect.