title: Evaluation of behavior and expression of receptor activator of nuclear factor-kappa B ligand in dorsal root Ganglia after sciatic nerve compression and application of nucleus pulposus in rats.
abstract: METHODS
  Experimental animal study.
  
  
  OBJECTIVE
  To evaluate pain-related behavior and changes in nuclear factor-kappa B (NF-kB), receptor activator of NF-kB (RANK), and ligand (RANKL) in dorsal root ganglia (DRG) after combined sciatic nerve compression and nucleus pulposus (NP) application in rats.
  
  
  BACKGROUND
  The pathological mechanisms underlying pain from lumbar-disc herniation have not been fully elucidated. RANKL are transcriptional regulators of inflammatory cytokines. Our aim was to evaluate pain-related behavior and RANKL expression in DRG after sciatic-nerve compression and application of NP in rats.
  
  
  METHODS
  MECHANICAL HYPERALGESIA AND RANKL EXPRESSION WERE ASSESSED IN THREE GROUPS OF RATS: NP+sciatic nerve compression (2 seconds), sham-operated, and controls (n=20 each). Mechanical hyperalgesia was measured every other day for 3 weeks using von Frey filaments. RANKL expression in L5 DRGs was examined at five and ten days after surgery using immunohistochemistry.
  
  
  RESULTS
  Mechanical hyperalgesia was observed over the 12-day observation period in the NP+nerve compression group, but not in the control and sham-operated animal groups (p<0.05). RANKL immunoreactivity was seen in the nuclei of L5 DRG neurons, and its expression was significantly upregulated in NP+nerve compression rats compared with control and sham-operated rats (p<0.01).
  
  
  CONCLUSIONS
  The exposure of sciatic nerves to mechanical compression and NP produces pain-related behavior and up-regulation of RANKL in DRG neurons. RANKL may play an important role in mediating pain after sciatic nerve injury with exposure to NP.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Matsuyama
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sakuma
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Miyako
authors.initials: M
authors.lastname: Suzuki
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Sumihisa
authors.initials: S
authors.lastname: Orita
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Kazuyo
authors.initials: K
authors.lastname: Yamauchi
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Gen
authors.initials: G
authors.lastname: Inoue
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Yasuchika
authors.initials: Y
authors.lastname: Aoki
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Tetsuhiro
authors.initials: T
authors.lastname: Ishikawa
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Miyagi
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Hiroto
authors.initials: H
authors.lastname: Kamoda
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Gou
authors.initials: G
authors.lastname: Kubota
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Oikawa
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Inage
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sainoh
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Sato
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Junichi
authors.initials: J
authors.lastname: Nakamura
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Toyone
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Takahashi
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Ohtori
keywords: Nerve; Nucleus pulposus; Pain; Rat; Receptor activator of nuclear factor-kappa B ligand