THE ALPHA(2) ADRENOCEPTOR AGONIST CLONIDINE SUPPRESSES SEIZURES, WHEREAS THE ALPHA(2) ADRENOCEPTOR ANTAGONIST IDAZOXAN PROMOTES SEIZURES - PONTINE MICROINFUSION STUDIES OF AMYGDALA-KINDLED KITTENS

This is the first report showing that microinfusion of alpha(2) adreno receptor agonists and antagonists into the vicinity of the locus cerul eus (LC) have contrasting effects on evoked amygdala-kindled seizure s usceptibility. Microinfusions (1 mu l) of the alpha(2) agonist clonidi ne (CLON) and of the alpha(2) antagonist idazoxan (IDA) were made over 1 min through cannulae in the LC ipsilateral to the kindled amygdala in 6 kittens. Order of administered drugs (CLON vs. IDA) and dosages ( n=3 each) were partly counterbalanced. Focal and convulsive seizure th resholds were evaluated 10-12 mid post-infusion and compared to thresh olds obtained during two, interspersed control conditions (vehicle con trol=1 mu l microinfusion of sterile saline; sham control=needle inser tion only). CLON significantly elevated focal and generalized seizure thresholds, whereas IDA significantly reduced seizure thresholds when compared to controls. Magnitude of effects was dose-dependent. These f indings confirm that norepinephrine (NE) is a potent antiepileptic age nt. Results also suggest that pontine microinfusions could eventually provide an alternative treatment option for medically refractory limbi c epilepsy.