[Amygdaloid kindling in variously aged infant rats and rekindling after maturation: epileptogenesis and its persistence].

To study amygdaloid kindling in variously aged infant rats and rekindling development after their maturation, 34 male Wistar rats were subjected to initial kindling 13 days after birth (13-day-old group, 9 rats), 16 days after birth (16-day-old group, 9 rats), 18 days after birth (18-day-old group, 7 rats), or 26 days after birth (26-day-old group, 9 rats). Each group received reoperation on the 70th day, and was subjected to rekindling 5 days after operation. Also, a control group of mature rats was initially kindled at the age of 75 days and rekindled after 2 months (75-day-old group, 11 rats). The obtained results are summarized as follows. I. Results of initial kindling: (1) a significant positive correlation was found between the age of the 4 groups of rats and the after-discharge threshold of infant rats (p < 0.05), (2) significant correlations were not found between the age of the 4 groups of infant rats and the stimulation numbers inducing C0-2 and C0-4 stage symptoms, (3) a significant positive correlation was found between the age of the 4 groups of infant rats and the stimulation number inducing C3-4 symptoms (p < 0.05). II. Results of rekindling: (1) significant negative correlations were found between the age of the 4 groups at initial kindling and the stimulation numbers inducing C0-2, C3-4 and C0-4 symptoms (p < 0.05-0.0001). III. Ratio of initial kindling and rekindling: (1) significant negative correlations were found between the age at initial kindling and the C0-2 and C0-4 stimulation number ratios (p < 0.00001), (2) a negative but not significant correlation was found between the C3-4 stimulation number ratio and age at initial kindling. These results suggest that in infant rats amygdaloid excitability is stronger, when the younger the rat, and that the later in the infant period the epileptogenesis is acquired, the stronger is it preserved even after maturation as high amygdaloid excitability.