Comparing the Excitability of Hippocampal Neurons in Focal and Generalized Stages of Kindling Induced Seizures in Rat

Amygdala kindling is accompanied with alteration of the electrophysiological characteristics of pyramidal cells in CA1 area of hippocampus. However, it is not clear that when and in which seizure stage do these changes occur during kindling. In the present study, changes in the electrophysiological properties of hippocampal CA1 pyramidal neurons following partial amygdala kindling in rats were compared to full kindled state.

Animals were rapidly kindled by 1 ms square waves, 50 Hz, for 3 s. These stimulations were applied to the amygdala 12 times per day at 5 min intervals. Animal received kindling stimulation until achieving stage 2 (partial kindled group) and stage 5 (full kindled group). 24 hours after the last kindling stimulation electrophysiological properties of CA1 pyramidal neurons were assessed by using whole-cell patch clamp technique.

Obtained data from amygdala kindling showed that adaptation index, Rheobase, utilization time and the amplitude of afterhyperpolarization potential in partial kindled and full kindled compare to control were significantly decreased and the numbers of action potentials were significantly increased.

The present findings showed that in spite of in partial amygdala kindling, the number of stimulations that rats will receive is lower than full kindled animal but it can change neuronal hyperexcitability through alteration of the electrophysiological characteristics.