To assess the development of kindling effect induced with low frequency electrical stimulations, we stimulated the lateral amygdala (AM group, 5 cats) and the dorsal hippocampus (HP group, 5 cats) bipolarly, once a day, with 2 mA base to peak, biphasic 1 msec square-wave pulses. In each stimulation we measured the longest inter-pulse interval required for the provocation of epileptic afterdischarge (AD), defined as the pulse-interval threshold; and the number of stimulating pulses required for the provocation of AD at this pulse-interval, defined as the pulse-number threshold. The observed behavioral seizures were classified into 6 stages in both the AM and HP group according to the conventional classification. In the AM group, an increase of the pulse-interval threshold and a decrease of the pulse-number threshold were observed during the kindling process. At the completion of kindling, a generalized convulsion was provoked with 1,200-1,600 msec pulse-intervals, and with 8-12 stimulating pulses. In the HP group an increase of the pulse-interval threshold and a decrease of the pulse-number threshold were observed in the early seizure stages, but not so significantly as the AM group. In the late seizure stages, a decrease of the pulse-interval threshold and an increase of the pulse-number threshold were observed. The observed behavioral stage of seizures in the two groups were similar to that of the conventional high-frequency kindling.(ABSTRACT TRUNCATED AT 250 WORDS)