SEIZURE PATTERNS IN KINDLING AND CORTICAL STIMULATION MODELS OF EXPERIMENTAL EPILEPSY

A large number of animal models has been proposed for the evaluation o f the anticonvulsant effect of antiepileptic drugs. Various seizure pa tterns are produced and differences are frequently observed in anticon vulsant effect estimates obtained for the same drug in different model s. The incidence of seizures and the threshold for the induction are u sually the only measures used for the determination of the anticonvuls ant effect. However, behavioural components expressed during seizures induced by different means are likely to differ considerably. The aim of this study was to provide a detailed behavioural description of ict al and post-ictal components in two models of electrically induced sei zure activity: kindling and cortical stimulation model (CSM). Seizure activity was induced in two groups of 6 Wistar-derived rats. Ictal and post-ictal behaviours were recorded on video tape and quantified usin g a computer supported frame-by-frame encoding of the behavioural comp onents. We encoded the duration and rate of occurrence of the followin g behavioural items: whisker movements, eye closure, myoclonic jerk, f acial gasping, forelimb clonus, forelimb tonus, hindlimb tonus, immobi lity and chewing. It appears that both models are, in many respects, q ualitatively similar. However, the models differ quantitatively. Behav ioural expression of seizure activity differs in the following respect s: (1) the total duration of the seizure induced by cortical stimulati on is shorter than by kindling; (2) seizure activity in the CSM occurs mainly during stimulation, while in amygdala kindling, it occurs ther eafter; and (3) seizures evoked in the CSM comprise relatively less vi olent behavioural items than in the amygdala kindling. The evaluation of the ictal and post-ictal behavioural components suggests that behav ioural analysis could assist in the detection of differences in the me chanisms of action of antiepileptic drugs. In addition, observational measures can also be used to assess animal distress inflicted by diffe rent experimental procedures. (C) 1997 Elsevier Science B.V.