Effects of hypoxic-ischemic encephalopathies on kindling in the immature brain

The effects of hypoxia and ischemia on subsequent kindling in the immature animal were assessed using three experimental designs. In the first experiment, 15- and 30-day-old rats were exposed to either 15 or 30 min of 6% oxygen and then subsequently kindled. In the second experiment, 15- and 30-day-old rats underwent unilateral carotid ligation followed by kindling in the ipsilateral amygdala. In the third experiment, the Levine procedure was used (unilateral carotid ligation followed by exposure to 6% oxygen) and rats were subsequently kindled in the amygdala either ipsilateral or contralateral to the side of the carotid ligation. Hypoxia and carotid ligation alone failed to result in any significant difference from controls in rate of kindling. In rats that underwent the Levine procedure and were kindled in the amygdala ipsilateral to the side of the carotid ligation, there was a marked inhibition of kindling. These results suggest that although mild hypoxia or ischemia did not alter seizure susceptibility, moderate to severe hypoxia-ischemia inhibited the development of generalized seizures. The mechanism of this inhibition is not known.