title: Up-regulation of p55 TNF alpha-receptor in dorsal root ganglia neurons following lumbar facet joint injury in rats.
abstract: The rat L5/6 facet joint is multisegmentally innervated from the L1 to L6 dorsal root ganglia (DRG). Tumor necrosis factor (TNF) is a known mediator of inflammation. It has been reported that satellite cells are activated, produce TNF and surround DRG neurons innervating L5/6 facet joints after facet injury. In the current study, changes in TNF receptor (p55) expression in DRG neurons innervating the L5/6 facet joint following facet joint injury were investigated in rats using a retrograde neurotransport method followed by immunohistochemistry. Twenty rats were used for this study. Two crystals of Fluorogold (FG; neurotracer) were applied into the L5/6 facet joint. Seven days after surgery, the dorsal portion of the capsule was cut in the injured group (injured group n = 10). No injury was performed in the non-injured group (n = 10). Fourteen days after the first application of FG, bilateral DRGs from T13 to L6 levels were resected and sectioned. They were subsequently processed for p55 immunohistochemistry. The number of FG labeled neurons and number of FG labeled p55-immunoreactive (IR) neurons were counted. FG labeled DRG neurons innervating the L5/6 facet joint were distributed from ipsilateral L1 to L6 levels. Of FG labeled neurons, the ratio of DRG neurons immunoreactive for p55 in the injured group (50%) was significantly higher than that in the non-injured group (13%). The ratio of p55-IR neurons of FG labeled DRG neurons was significantly higher in total L1 and L2 DRGs than that in total L3, 4, 5 and 6 DRGs in the injured group (L1 and 2 DRG, 67%; L3, 4, 5 and 6 DRG, 37%, percentages of the total number of p55-IR neurons at L1 and L2 level or L3-6 level/the total number of FG-labeled neurons at L1 and L2 level or L3-6 level). These data suggest that up-regulation of p55 in DRG neurons may be involved in the sensory transmission from facet joint injury. Regulation of p55 in DRG neurons innervating the facet joint was different between upper DRG innervated via the paravertebral sympathetic trunks and lower DRG innervated via other direct routes.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chiba 260-8670, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sakuma
authors.forename: Seiji
authors.initials: S
authors.lastname: Ohtori
authors.forename: Masayuki
authors.initials: M
authors.lastname: Miyagi
authors.forename: Tetsu
authors.initials: T
authors.lastname: Ishikawa
authors.forename: Gen
authors.initials: G
authors.lastname: Inoue
authors.forename: Hideo
authors.initials: H
authors.lastname: Doya
authors.forename: Takana
authors.initials: T
authors.lastname: Koshi
authors.forename: Toshinori
authors.initials: T
authors.lastname: Ito
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: Hideshige
authors.initials: H
authors.lastname: Moriya
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Takahashi
mesh_terms: D000818:Animals; D005727:Ganglia, Spinal / Q000378:metabolism* / Q000473:pathology; D008159:Lumbar Vertebrae / Q000293:injuries* / Q000294:innervation / Q000378:metabolism; D008297:Male; D009474:Neurons / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000378:metabolism*; D053319:Tumor Necrosis Factor Decoy Receptors / Q000378:metabolism*; D015854:Up-Regulation; D021801:Zygapophyseal Joint / Q000293:injuries* / Q000294:innervation / Q000378:metabolism
chemical_list: D047888:Receptors, Tumor Necrosis Factor, Type I; D053319:Tumor Necrosis Factor Decoy Receptors; C069521:recombinant human tumor necrosis factor-binding protein-1