Selective facilitation of kindled seizures from the amygdala after hippocampal lesions induced by perforant path stimulation.

Intermittent electrical stimulation of the perforant path (PPS) for 24 h in anesthetized rats results in impairment of paired pulse inhibition, neuronal loss in the dentate gyrus and hippocampus, and delayed spontaneous seizures. One week after PPS, animals showed a dramatic decrease in afterdischarge threshold and increase in afterdischarge duration from the basolateral amygdala, whereas no changes in after-discharge properties were observed from the dentate gyrus. Animals also showed a remarkable facilitation of amygdala kindling, but not of perforant path kindling. After amygdala kindling, some animals showed spontaneous seizures. PPS may recruit amygdala into the epileptogenic circuit, resulting in "latent' kindling and development of spontaneous seizures.