Low-frequency kindling as a new experimental model of epilepsy

Ten cats were stimulated twice a day in the lateral amygdala with low-frequency stimulation of about 3 Hz until generalized convulsion occurred. After the completion of kindling, the longest interpulse interval required for provocation of generalized convulsion (pulse-interval threshold) was determined in each subject. The pulse-interval threshold was 1300 ms in five cats, and 900 ms in five other cats. Then the stability of pulse-interval threshold and of the number of stimulating pulses required for provocation of afterdischarge when the stimulation was delivered with the pulse-interval threshold (pulse-number threshold) was tested. The pulse-interval threshold, pulse-number threshold, and duration of afterdischarge in each stimulation did not change statistically at the interstimulation interval from 24 h to 7 days. Phenobarbital and diphenylhydantoin elevated the pulse-number threshold significantly. We propose that low-frequency kindling is a valuable experimental model of epilepsy in assessing simply and precisely the susceptibility of the epileptic focus itself and the severity of epileptic seizures.