title: Efferent projections of the nucleus raphe magnus.
abstract: This study was performed to identify supraspinal efferents of the nucleus raphe magnus (NRM) in the rat using the anterograde tracer phaseolus vulgaris leucoagglutinin (PHA-L). NRM-derived PHA-L-ir fibers, with putative terminals, were identified in regions including the lateral hypothalamus, parafascicular nucleus, ventral lateral periaqueductal gray (PAG), locus coeruleus, parabrachial nucleus, A7, A5, and nucleus tractus solitarius. Projections to the PAG demonstrate reciprocity in PAG-NRM connectivity that may modulate the PAG-NRM-spinal cord pathway. The NRM may contribute to supraspinal modulation of nociception by efferents identified in the PAG, as well as locus coeruleus, A7, and A5, which have been shown to project to the spinal cord dorsal horn. Our results provide neuroanatomical support for NRM involvement in supraspinal mechanism(s) for modulation of nociception.
authors.affiliation: Neuroendocrine Unit, University of Rochester School of Medicine and Dentistry, NY 14642.
authors.forename: L J
authors.initials: LJ
authors.lastname: Sim
authors.forename: S A
authors.initials: SA
authors.lastname: Joseph
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000033:anatomy & histology / Q000502:physiology; D004525:Efferent Pathways / Q000166:cytology / Q000502:physiology*; D006651:Histocytochemistry; D008297:Male; D009619:Nociceptors / Q000502:physiology; D010835:Phytohemagglutinins; D011903:Raphe Nuclei / Q000166:cytology / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013194:Staining and Labeling; D013238:Stereotaxic Techniques
chemical_list: D010835:Phytohemagglutinins; C100156:leukoagglutinins, plants