اثر تحريك الكتريكي هسته خلفي سجافي بر القاء خودمصرفي مورفين در رات

Electrical Stimulation of Nucleus Raphe Dorsalis on Initiation of Morphine Self-Administration in Rats

Previous studies have shown that addiction is caused by abnormality of neurotransmission. Serotonin (5-HT), dopamine (DA) and endogenous opiates are the most important neurotransmitters in addiction, and nucleus raphe dorsalis (NRD) is the important site that releases or modulates these substances. Release of 5-HT can be evoked by focal electrical stimulation of NRD. In this study electrical stimulation (30 min: pulse 0.5ms, 150mA, 20Hz) was used in the antero-dorsal part of the nucleus raphe dorsalis. During all sessions lever-pressing behavior was measured. After the last test session, withdrawal syndrome signs (jumping, wet dog shakes, and diarrhea) in the naloxone-induced behaviour, were measured. The results show that the electrical stimulation in NRD produced significant decreased in initiation of morphine self-administration during 10 consecutive 2-h sessions. Also withdrawal syndrome signs decreased by application of electrical stimulation in NRD. It is concluded that electrical stimulation in NRD enhances the serotonergic and endogenous opiate transmission, and this activation might be involved in reduction of craving for morphine.