Alpha-noradrenaline modulation of D,L-allylgycine seizures.

The preferential alpha 2-noradrenergic agonist clonidine dose-relatedly increased the onset of seizures and mortality times, and decreased severity in rats treated with D,L-allylglycine. These effects were reduced by a dose (2.5 mg/kg) of the preferential alpha 2-antagonist yohimbine, which was itself inactive on the allylglycine seizures. Yohimbine 10 mg/kg alone decreased onset and mortality times. The preferential alpha 1-antagonist prazosin had a slight anticonvulsant effect. These results suggest that the reduction of NA release at alpha 2-noradrenergic receptors or antagonism of noradrenaline effects at alpha 1-receptors exerts seizure suppressant effects.