EFFECT OF A SUBCONVULSANT DOSE OF KAINIC ACID ON THRESHOLDS FOR PHENOMENA ELICITED BY ELECTRICAL-STIMULATION OF SENSORIMOTOR CORTEX IN RATS

Electrical stimulation of sensorimotor cortex was used to study early and late effects of administration of kainic acid in a dose (6 mg/kg i .p.) eliciting only nonconvulsive seizures in rats. Thresholds for eli citation of four phenomena-movements directly related to stimulation; epileptic afterdischarges (ADs) of the spike-and-wave type; clonic sei zures accompanying these ADs; and mixed type of ADs where spike-and-wa ve activity transgresses into limbic type of epileptic phenomena-were measured. Acute administration of kainic acid resulted in a decrease o f the threshold for elicitation of mixed type of ADs. In contrast, 1 w eek after kainic acid administration, the thresholds for stimulation-b ound movements, spike-and-wave ADs and concommitant clonic seizures we re increased, but the threshold for mixed type of ADs remained unchang ed. The changes in thresholds tended to decrease 2 weeks after kainic acid but statistical significance was reached only for stimulus-bound movements. In addition, repetition of stimulation series after 1 as we ll as 2 weeks markedly influenced the thresholds. (C) 1998 Elsevier Sc ience B.V. All rights reserved.