Facilitation of focal cobalt-induced epilepsy after lesions of the noradrenergic locus coeruleus system.

In this study we analyzed the electrophysiological and clinical effects of selective removal of the forebrain noradrenergic projection from the locus coeruleus, induced by bilateral injections of 6-hydroxydopamine into the dorsal tegmental bundle on focal cobalt-induced epilepsy. Noradrenaline depletion caused a marked potentiation of the epilepsy by increasing the duration and intensity of both the clinical and electrophysiological epileptic parameters: epileptic discharges and myoclonic jerks started earlier; spiking and clinical activity were facilitated; duration of the epileptic syndrome was prolonged. On the basis of the present and previous results it is proposed that the ascending noradrenergic system plays a modulatory role on the spread of paroxysmal activities and on the severity of cobalt-induced epilepsy.