title: A spinal cord pathway connecting primary afferents to the segmental sympathetic outflow system.
abstract: The sympathetic innervation of lumbar dorsal root ganglia (DRGs) and the possible presence of spinal cord circuits connecting primary sensory afferents to the sympathetic outflow to DRGs were investigated. We used simultaneous tracing of the sympathetic input to and sensory output from DRGs. Adult male rats received unilateral microinjections of the Bartha strain of pseudorabies virus into four lumbar DRGs. At 24 h post-inoculation, productive infection was detected in both DRG neurons and sympathetic postganglionic neurons. Infection of spinal cord neurons was first observed in sympathetic preganglionic neurons of the intermediolateral column. Subsequently, the infection spread to the contralateral intermediolateral column, the area around the central canal and the superficial dorsal horn layers. To investigate the relationship between infected spinal cord neurons and primary afferents from the corresponding DRGs, we injected pseudorabies virus for retrograde tracing together with cholera toxin B for anterograde tracing. We found that infected LIV/LV and LX neurons were in close apposition to cholera toxin B labeled afferents. Importantly, immunohistochemical detection of bassoon, a pre-synaptic zone protein, identified such contacts as synapses. Together, this suggests synaptic contacts between primary sensory afferents and neurons regulating sympathetic outflow to corresponding DRGs.
authors.affiliation: Department of Neuroscience, Karolinska Institutet, Retziusväg 8, 17177 Solna, Sweden. Christoph.Hofstetter@neuro.ki.se
authors.forename: C P
authors.initials: CP
authors.lastname: Hofstetter
authors.forename: J P
authors.initials: JP
authors.lastname: Card
authors.forename: L
authors.initials: L
authors.lastname: Olson
mesh_terms: D000344:Afferent Pathways / Q000166:cytology* / Q000502:physiology; D000818:Animals; D001370:Axonal Transport / Q000502:physiology; D002772:Cholera Toxin; D005727:Ganglia, Spinal / Q000098:blood supply / Q000166:cytology* / Q000502:physiology; D011558:Herpesvirus 1, Suid / Q000378:metabolism; D008161:Lumbosacral Region; D008297:Male; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010523:Peripheral Nervous System Diseases / Q000378:metabolism / Q000503:physiopathology; D017729:Presynaptic Terminals / Q000502:physiology / Q000648:ultrastructure*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow / Q000502:physiology; D013116:Spinal Cord / Q000166:cytology* / Q000502:physiology / Q000821:virology; D013126:Spinal Nerve Roots / Q000166:cytology* / Q000502:physiology / Q000821:virology; D013194:Staining and Labeling / Q000379:methods; D017779:Sympathetic Fibers, Postganglionic / Q000166:cytology / Q000378:metabolism; D013564:Sympathetic Nervous System / Q000166:cytology* / Q000502:physiology / Q000821:virology; D009435:Synaptic Transmission / Q000502:physiology
chemical_list: C113688:Bsn protein, rat; D009419:Nerve Tissue Proteins; D002772:Cholera Toxin