CATECHOLAMINES AND CONVULSIONS

Severe depletion of brain noradrenaline (norepinephrine) and separately of brain dopamine was induced in rats by intracerebral injection of the selective neurotoxin 6-hydroxydopamine, and the susceptibility of the treated animals to various seizure-inducing manipulations was examined. A significant potentiation of the seizures induced both by Metrazol and by electroconvulsive shock was found in animals depleted of brain noradrenaline, but no alteration was seen after depletion of brain dopamine on either measure. The catecholaminergic drug cocaine also induced seizures, but these did not depend on either brain noradrenaline or dopamine as they continued to occur in the virtual absence of either catecholamine. Cocaine induces seizures by a non-specific toxic mechanism and noradrenaline, but not dopamine, is involved in reducing the susceptibility of the CNS to the several distinct forms of seizure induction examined.