The role of the nucleus accumbens and nigrostriatum in enkephalin-induced myoclonus.

Local administration of the enkephalin-analog. D-Ala2-Met5-enkephalinamide (DALA) into the nucleus accumbens and caudate nucleus of the rat resulted in myoclonic contrations (MC) of the submandibular muscles and epileptic discharges in the electrocorticogram. These phenomena were blocked by naloxone but not by haloperidol. Similar administration of DALA into the substantia nigra compacta failed to produce MC. A possible involvement of endogenous opiates in the nucleus accumbens and striatum is suggested in the pathogenesis of some types of myoclonus.