Electroencephalographic, Behavioral and Pathologic Characteristics in Experimental Complex Partial Seizure Induced by Microinjection of Kainic Acid into the Unilateral Amygdala in the Rat

ABSTRACT

Kainic acid(KA) is an excitotoxic analogue of glutamate which is now widely used in the studies of epilepsy. Electroencephalographic, behavioral and pathologic observation were done for 2 months after microinjection of kainic acid(Kainic acid group;0.4 microgram, 0.8 microgram, 1.2 microgram, 1.6 microgram, 2.0 microgram, 3.0 microgram) and phosphate buffer solution(Control group) into the left basolateral amygdala(AMG) in 30 Spaque-Doley rats. The control group showed no change in EEG and behavior during the observation period and pathologic findings were normal. One of four rats which 1.2 microgram of KA was injected, four of six rats of 1.6 microgram, all six rats of 2.0 microgram, one of four rats of 3.0 microgram developed acute complex partial seizure and multiple epileptic spikes with high amplitude in EEG. One of four rats of 1.2 microgram, one of six rats of 1.6 microgram, three of six rats of 2.0 microgram, showed spontaneous limbic seizure 14~21days after kainic acid injection. Among those which developed spontaneous limbic seizure, two rats demonstrated spontaneous secondarily generalized seizure 30~60days after kainic acid injection. Pathological examination revealed focal necrosis with perifocal gliosis at the tip of the cannula in the left amygdala. Neuronal cell loss was observed in the CA3 portion of pyramidal cell layer of the hippocampus on the injected side of KA, which developed spontaneous secondarily generalized seizure. But the cellular architecture was normal in the contralateral hippocampus. This is regarded as a good medel of spontaneous generalized complex partial seizure, which is similar to that of temporal lobe epilepsy in human.