[Kindling of the rat pyriform cortex in the process of aging]

The author investigated seizure susceptibility in 10-12-month-old male sprague-Dawley rats (elderly group) by kindling of the pyriform cortex (PC). Male rats (3-4 mo.) of the same strain were used as the control group. The kindling development of the elderly group was significantly slower than that of the control group because stages 1 and 2, which are indicative of partial seizures, were prolonged. The incidence of regression of seizure stage during the kindling process was higher in the elderly group than in the control group (70% and 40%, respectively), but not significantly. In addition, the elderly group showed a shorter duration of afterdischarges (AD) through the kindling process, and afterdischarge threshold in the PC was slightly elevated in the elderly group as compared with the control group, but not significantly. There were no significant differences between the two groups in the incidence of falling, and in the latency for falling at the first stage 5 seizure (generalized convulsion). The results indicate that the elderly group has difficulty in acquisition of epileptogenesis, while there is no apparent change in the susceptibility to generalized convulsion as compared with the control group.