[Amygdaloid kindling in weanling rat and rekindling upon maturization]

To understand the epileptic phenomenon in the immature brain and to investigate whether or not the epileptogenesis acquired in young age is retained after maturation, we carried out the amygdaloid kindling preparation (AM-K) on rat. Ten 3-week-old Wistar rats (3-week-old group) and ten 10-week-old rats (10-week-old group) were stimulated every 2 hours during 09:00-17:00, from five days after operation (Experiment 1). Nine kindled weanling rats (K-group) and ten weanling rats with no stimulation only electrodes implantation (non-K-group) were rekindled upon maturization (Experiment II). Stages of AM-K were classified according to the criteria of Racine. The results obtained were as follows: 1) The 3-week-old group needed significantly fewer stimulations and a shorter AD-durations during early stages (C0-2) of amygdaloid kindling, in comparison with the 10-week-old group. However, there was no significant difference between the two groups as to stimulations and AD-duration during later stages (C3-4) of the kindling. 2) The K-group were rekindled significantly fewer stimulations and a shorter AD-durations than non-K group during early stages. On the other hand, there was not significant difference between the two groups as to stimulation and AD-duration during later stages of the kindling. From the results, the following conclusions were made; The seizure susceptibility of weanling rat's limbic system is high and the epileptogenesis in the limbic system can be maintained even up to adulthood.