title: Sensory innervation of lumbar vertebral bodies in rats.
abstract: METHODS
  Using a retrograde neurotracing method with Fluoro-Gold (FG), the level at which dorsal root ganglions (DRGs) innervate the L2 and L5 vertebral bodies and the innervation pathways were investigated in rats.
  
  
  OBJECTIVE
  To clarify the levels at which DRGs innervate the lumbar vertebral bodies and to determine the pathways from the L2 and L5 vertebral bodies to DRGs.
  
  
  BACKGROUND
  Elderly patients with osteoporosis sometimes experience lumbar vertebral fracture and may also feel diffuse nonlocalized pain in the back, lateral portion of the trunk, and area surrounding the iliac crest. However, the pattern of sensory innervation of vertebral bodies remains unclear.
  
  
  METHODS
  Forty female Sprague-Dawley rats were used. FG crystals were applied to the L2 (L2 vertebra group) or L5 (L5 vertebra group) vertebral bodies via an anterior approach, and numbers of labeled neurons in DRGs from T10 to L6 were counted. To determine sensory pathways, bilateral sympathectomy was performed.
  
  
  RESULTS
  In nonsympathectomy animals, FG-labeled neurons were present in DRGs from T11 through L3 in the L2 vertebra group and from T13 through L6 in the L5 vertebra group. The number of labeled neurons following sympathectomy was not significantly different in L1, L2, and L3 DRGs in the L2 vertebra group or in L3, L4, L5, and L6 DRGs in the L5 vertebra group from those in nonsympathectomy animals. In contrast, fewer labeled DRG neurons were present in sympathectomy animals at T11, T12, and T13 in the L2 vertebra group, and at T13, L1, and L2 in the L5 vertebra group than in nonsympathectomy animals (P < 0.01).
  
  
  CONCLUSIONS
  Sensory nerve fibers in the L2 and L5 vertebral bodies are derived from the T11-L3 and T13-L6 DRGs, respectively. Some sensory nerves from the L2 and L5 vertebral bodies enter the paravertebral sympathetic trunks and reach the DRGs at multisegmental levels. The present findings regarding multisegmental innervation to vertebral bodies may explain the diffuse pain that originates within osteoporotic vertebral fractures in elderly patients.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan. sohtori@faculty.chiba-u.jp
authors.forename: Seiji
authors.initials: S
authors.lastname: Ohtori
authors.forename: Gen
authors.initials: G
authors.lastname: Inoue
authors.forename: Takana
authors.initials: T
authors.lastname: Koshi
authors.forename: Toshinori
authors.initials: T
authors.lastname: Ito
authors.forename: Tomoko
authors.initials: T
authors.lastname: Watanabe
authors.forename: Masaomi
authors.initials: M
authors.lastname: Yamashita
authors.forename: Kazuyo
authors.initials: K
authors.lastname: Yamauchi
authors.forename: Munetaka
authors.initials: M
authors.lastname: Suzuki
authors.forename: Hideo
authors.initials: H
authors.lastname: Doya
authors.forename: Hideshige
authors.initials: H
authors.lastname: Moriya
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Takahashi
mesh_terms: D000818:Animals; D005260:Female; D005456:Fluorescent Dyes; D005727:Ganglia, Spinal / Q000033:anatomy & histology*; D008159:Lumbar Vertebrae / Q000294:innervation*; D009475:Neurons, Afferent; D010784:Photomicrography; D051381:Rats; D017207:Rats, Sprague-Dawley; D013194:Staining and Labeling / Q000379:methods; D013266:Stilbamidines; D013562:Sympathectomy
chemical_list: C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D005456:Fluorescent Dyes; D013266:Stilbamidines