[Influence of aging on the unilateral and the contralateral amygdaloid kindling in rats].

To investigate the seizure susceptibility in the rat after the mature period, the unilateral (primary site, left) and the subsequent contralateral (secondary site, right) amygdaloid kindling were examined in 2-3-month-old (n = 12, group A), 12-month-old (n = 11, group B), and 18-month-old (n = 7, group C) male Sprague-Dawley rats. At both of the primary and the secondary sites, the number of stimulations required to produce a generalized convulsion with falling (stage 5) increased as the age progressed, and there was a significant difference in the number of stimulations to reach stage 5 between groups A and B, and between groups A and C. These findings suggest that the age-related retardation of the development of amygdaloid kindling reflects aging changes of synaptic transmission. On the other hand, positive transfer effect (a facilitory effect of the primary site amygdaloid kindling on the development of the secondary site amygdaloid kindling) was observed in all of the three groups. This results suggests that both in and after the mature period, the secondary site amygdaloid kindling in the rats utilizes proconvulsant neuroplastic changes in the brainstem that has been already established by the primary site amygdaloid kindling.