title: Evaluation of behavior and expression of NaV1.7 in dorsal root ganglia after sciatic nerve compression and application of nucleus pulposus in rats.
abstract: OBJECTIVE
  The pathomechanisms of pain resulting from lumbar disc herniation have not been fully elucidated. Prostaglandins and cytokines generated at the inflammatory site produce associated pain; however, non-steroidal anti-inflammatory drugs and steroids are sometimes ineffective in patients. Tetrodotoxin-sensitive voltage-gated sodium (NaV) channels are related to sensory transmission in primary sensory nerves. The sodium channel NaV1.7 has emerged as an attractive analgesic target. The purpose of this study was to evaluate pain-related behavior and expression of NaV1.7 in dorsal root ganglia (DRG) after combined sciatic nerve compression and nucleus pulposus (NP) application in rats.
  
  
  METHODS
  Rats were divided into three groups and underwent either sciatic nerve compression with NP for 2 s using forceps (n = 20), sham operation with neither compression nor NP (n = 20), or no operation (controls, n = 20). Mechanical hyperalgesia was measured every second day for three weeks using von Frey filaments. NaV1.7 expression in L5 DRG was examined 7 and 14 days after surgery using immunohistochemistry. The number of neurons immunoreactive for NaV1.7 was compared among the three groups.
  
  
  RESULTS
  Mechanical hyperalgesia was found over the 14-day observation in the nerve compression plus NP application group, but not in the sham-operated or control groups (P < 0.05). NaV1.7 expression in L5 DRG was up-regulated in the nerve compression plus NP application group, compared with sham-operated and control rats (P < 0.01).
  
  
  CONCLUSIONS
  Our results indicate that nerve compression plus NP application produces pain-related behavior. We conclude that NaV1.7 expression in DRG neurons may play an important role in mediating pain from sciatic nerves after compression injury and exposure to NP.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan.
authors.forename: Michiaki
authors.initials: M
authors.lastname: Mukai
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sakuma
authors.forename: Miyako
authors.initials: M
authors.lastname: Suzuki
authors.forename: Sumihisa
authors.initials: S
authors.lastname: Orita
authors.forename: Kazuyo
authors.initials: K
authors.lastname: Yamauchi
authors.forename: Gen
authors.initials: G
authors.lastname: Inoue
authors.forename: Yasuchika
authors.initials: Y
authors.lastname: Aoki
authors.forename: Tetsuhiro
authors.initials: T
authors.lastname: Ishikawa
authors.forename: Masayuki
authors.initials: M
authors.lastname: Miyagi
authors.forename: Hiroto
authors.initials: H
authors.lastname: Kamoda
authors.forename: Gou
authors.initials: G
authors.lastname: Kubota
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Oikawa
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Inage
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sainoh
authors.forename: Jun
authors.initials: J
authors.lastname: Sato
authors.forename: Junichi
authors.initials: J
authors.lastname: Nakamura
authors.forename: Masashi
authors.initials: M
authors.lastname: Takaso
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Toyone
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Takahashi
authors.forename: Seiji
authors.initials: S
authors.lastname: Ohtori
mesh_terms: D000818:Animals; D001416:Back Pain / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D005727:Ganglia, Spinal / Q000378:metabolism*; D006930:Hyperalgesia / Q000378:metabolism; D007405:Intervertebral Disc Displacement / Q000378:metabolism*; D008297:Male; D062556:NAV1.7 Voltage-Gated Sodium Channel / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve / Q000737:chemistry / Q000293:injuries* / Q000378:metabolism
chemical_list: D062556:NAV1.7 Voltage-Gated Sodium Channel; C503480:Scn9a protein, rat