فعاليت نروني هسته اكومبنس متعاقب تحريك الكتريكي هسته خلقي سجافي در خلال خود مصرفي هرويين در رات

NEURONAL RESPONSES IN NUCLEUS ACCUMBENS AFTER ELECTRICAL STIMULATION OF NUCLEUS RAPHE DORSALIS AND HEROIN SELF-ADMINISTRATION IN RATS

Introduction: Extracellular recordings were recorded from nucleus accumbens septi (NAS) after electrical stimulation of nucleus raphe dorsalis(NRD) in halothane-anesthetized rats. Methods : In this study, electrical stimulation (30 min: pulse0.5ms, 150µA, 20Hz) was inducted in the antero-dorsal part of the nucleus raphe dorsalis . During all sessions, lever- pressing behavior was measured. After the last test session, basal firing rates were recorded from nucleus accumbens septi(NAS) . Also, extracellular recordings were recorded after administration of heroin (0.5mglkg s.c.) and naloxane (5mg/kg s.c.) . Results : The results showed that the electrical stimulation in NRD produced were significantly decreased after morphine self administration duringlO consecutive 2-h sessions. Basal firing rate was reduced in the heroin receiving group, but electrical stimulation prevented the reduction of basal firing rate in the test group. Heroin had mixed effects on spontaneous activity of NAS cells encountered. While most cells were excited, other cells were depressed or were unaffected. Conclusion : It is concluded that electrical stimulation in NRD enhances the serotonergic and endogenous opiate transmission, which might be the reason for reduction of craving for heroin.