PATTERNS OF UNIT RESPONSES TO INCREMENTAL DOSES OF MORPHINE IN CENTRAL GRAY, RETICULAR-FORMATION, MEDIAL THALAMUS, CAUDATE-NUCLEUS, HYPOTHALAMUS, SEPTUM AND HIPPOCAMPUS IN UNANESTHETIZED RATS

Freely moving rats previously implanted stereotaxically with 8 electrodes located in the central gray, mesencephalic reticular formation, medial thalamus (PF-CM complex), caudate nucleus, anterior and ventromedial hypothalamus, lateral septum and the dorsal hippocampus and 5 incremental doses of morphine (0.5, 1.0, 5.0, 10.0 and 30.0 mg/kg i.p.) followed by naloxone (1.0 mg/kg) were used to discriminate the effects of morphine and naloxone on spontaneous multiunit activity obtained from these CNS sites. These 6 injections provide the data to classify 5 patterns of responses and help to determine that each structure examined in the present study has its own pattern of response to morphine and/or its antagonist naloxone.