THE ALPHA(2)-AGONIST CLONIDINE SUPPRESSES SEIZURES, WHEREAS THE ALPHA(2)-ANTAGONIST IDAZOXAN PROMOTES SEIZURES - A MICROINFUSION STUDY IN AMYGDALA-KINDLED KITTENS

This is the first report showing that local, in vivo microinfusion of alpha(2)-adrenoreceptor agonists and antagonists have contrasting effe cts on amygdala-kindled seizure susceptibility. Microinfusions (1 mu l ) of the alpha(2)-agonist clonidine (CLON) and of the alpha(2)-antagon ist idazoxan (IDA) were made over 1 min through cannulae adjacent to s timulating electrodes in five amygdala-kindled kittens. Order of admin istered drugs (CLON vs. IDA) and dosages (n = 3 each) was partly count erbalanced. Focal and convulsive seizure thresholds were evaluated 10- 12 min post-infusion and compared to thresholds obtained during two, i nterspersed control conditions (vehicle control: 1 mu l microinfusion of sterile saline; sham control: needle insertion only). CLON signific antly elevated focal and generalized seizure thresholds, whereas IDA s ignificantly reduced seizure thresholds when compared to controls. Mag nitude of effects was dose-dependent. Results confirm and extend previ ous findings which employed unlocalized, in vivo manipulations to show that norepinephrine is a potent antiepileptic agent in the amygdala k indling preparation.