DECREASED CENTRAL HISTAMINE IN THE AMYGDALOID KINDLING RATS

This study was conducted to elucidate the role of central histamine (H A) in seizure susceptibility. We stimulated the left amygdala of rats to produce amygdaloid kindling. We sacrificed rats 1 h, 1 week and 1 m onth after the last kindled seizure, and measured the histamine conten ts and the histidine decarboxylase (HDC) activities of various brain r egions. One hour after the last kindled seizure, we found significant decreases in HA levels in the bilateral amygdala, hippocampus and dien cephalon in the kindled group. The HDC activities of the bilateral amy gdala and diencephalon were lower in the kindled group than in the con trol group. One week after the last kindled seizure, we also found a s ignificant decrease in the HA level in the bilateral amygdala. No sign ificant change was found in HA content or HDC activity 1 month after t he last kindled seizure. These results suggest that kindling suppresse s HA synthesis and that the reduced HA content is maintained until 1 w eek after the last kindled seizure. The reduced HA may play a role in the acquired kindled seizure susceptibility. (C) 1998 Elsevier Science B.V. All rights reserved.