Behavioural effects of a subconvulsive dose of kainic acid in rats

Kainic acid can induce a continuum of non-convulsive seizures characterised by epileptic automatisms and convulsive motor seizures depending on the dose. There are scarce data on the behavioural effects of low doses of kainate inducing only non-convulsive seizures. Therefore, we studied spontaneous behaviour of adult male rats using a method of positive habituation based on a detailed analysis of patterns and attention of animals to a stimulus object. Twenty-three animals were individually tested in the experimental arena on two consecutive days. Comparing the data from the first two exposures, a conspicuous habituation in all animals was observed. On experimental day 3, 12 rats received kainate (6 mg/kg intraperitoneally) and the remaining 11 animals received a physiological saline. After 1 h, animals were put into the arena with an object localised in the centre. It was found that both kainate and saline treated animals exhibited a significant increase in the total number of central area visits, and both the total and mean time spent in the vicinity of the object. However, the mean time spent was significantly shorter in kainate treated rats. Furthermore. kainate rats exhibited a significant decrease in rearing as compared with the controls. In addition, an epileptic automatism (wet dog shakes) was observed in seven out of 12 animals given kainate. The comparison of transition matrices between consecutive behavioural categories showed significant differences between the kainate and control groups. Our results demonstrate that a non-convulsive dose of kainate induced changes in the structure of spontaneous behaviour and impaired the processes related to maintenance of attention.