Effects of morphine on sensory‐evoked responses recorded from central gray, reticular formation, thalamus, hypothalamus, limbic system, basal ganglia, dorsal raphe, locus ceruleus, and pineal body

摘要: Field potential recordings of acoustic and photic-evoked responses were obtained from 15 brain sites freely behaving unanesthetized rats previously implanted stereotaxically with permanent electrodes. Several dosages morphine (1, 5, 10, 30, 50 mg/kg) examined. The activities recorded all the structures in this study, except cochlear nucleus (CoN), affected by morphine. Different sensitivities to threshold observed between structures, several exhibited dose-related patterns (ventromedial hypothalamus (VMH), caudate (CN), central gray (CG), hippocampus (Hipp), lateral septum (Spt)). sites, after initial dose morphine, did not recruit more subsequent doses drug, ie, all-or-none (pineal body (PB), medial thalamus (MTh), anterior (AH), mesencephalic reticular formation (MRF), dorsal raphe (DR)). In some induced increases response amplitudes, while other decreases amplitudes elicited. Biphasic responses, amplitude low drug higher dosages, also (VMH, CN, DR, CG, MRF). acoustic-evoked than photic responses. present observations indicated that (1) exerts effects many parts nervous system (CNS); (2) are sensitive others; (3) only a few exhibit and, thus, may represent direct action; (4) responses; (5) depressed activity increased others, elicited different structures.