ECS-INDUCED DOPAMINE RELEASE - EFFECTS OF ELECTRODE PLACEMENT, ANTICONVULSANT TREATMENT, AND STIMULUS-INTENSITY

Although electroconvulsive therapy (ECT) remains an important therapy for severe depression, its mechanism of action remains elusive. We pre viously demonstrated that there is a significant increase of interstit ial dopamine of neuronal origin in the rat striatum after electroconvu lsive shock (ECS) but not after chemically (flurothyl) induced seizure s. The present studies examined how electrode placement, stimulus inte nsity, and the administration of an anticonvulsant affect ECS-induced dopamine release in the rat striatum. Bilateral electrode placement re sulted in greater dopamine release than that produced by a unilaterall y applied stimulus. Pretreatment with sodium pentobarbital markedly de creased seizure duration but had no effect on the magnitude of the inc rease in interstitial dopamine. Finally, a higher voltage applied long er resulted in greater dopamine release without a concomitant increase in seizure duration. These data suggest that the passage of current m ay be directly responsible for certain ECS-induced chemical changes. T hese findings are discussed in the context of clinical observations th at challenge the traditional view that the production of generalized s eizures of adequate duration is both necessary and sufficient for a th erapeutic response to ECT.