title: Evaluation of behavior and neuropeptide markers of pain in a simple, sciatic nerve-pinch pain model in rats.
abstract: Pathomechanisms of injured-nerve pain have not been fully elucidated. Radicular pain and chronic constriction injury models have been established; however, producing these models is complicated. A sciatic nerve-pinch injury is easy to produce but the reliability of this model for evaluating pain behavior has not been examined. The current study evaluated pain-related behavior and change in pain markers in the dorsal root ganglion (DRG) of rats in a simple, sciatic nerve-pinch injury model. In the model, the sciatic nerve was pinched for 2 s using forceps (n = 20), but not injured in sham-operated animals (n = 20). Mechanical and thermal hyperalgesia were measured every second day for 2 weeks using von Frey filaments and a Hargreaves device. Calcitonin gene-related peptide (CGRP), activating transcription factor-3 (ATF-3), phosphorylated p38 mitogen activated protein (Map) kinase (p-p38), and nuclear factor-kappa B (NF-κB; p65) expression in L5 DRGs were examined at 4 and 7 days after surgery using immunohistochemistry. The proportion of neurons immunoreactive for these markers was compared between the two groups. Mechanical (during 8 days) and thermal hyperalgesia (during 6 days) were found in the pinch group rats, but not in the sham-operated animals (p < 0.05); however, hyperalgesia was not significant from days 10 to 14. CGRP, ATF-3, p-p38, and NF-κB expression in L5 DRGs was upregulated in the nerve-injured rats compared with the sham-operated rats (p < 0.01). Our results indicate that a simple sciatic nerve pinch produced pain-related behavior. Upregulation of the pain-marker expression in the nerve-injury model suggested it could be used as a model of pain. However, it was not considered as suitable for long-term studies.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Hirose
authors.forename: Nahoko
authors.initials: N
authors.lastname: Iwakura
authors.forename: Sumihisa
authors.initials: S
authors.lastname: Orita
authors.forename: Masaomi
authors.initials: M
authors.lastname: Yamashita
authors.forename: Gen
authors.initials: G
authors.lastname: Inoue
authors.forename: Kazuyo
authors.initials: K
authors.lastname: Yamauchi
authors.forename: Yawara
authors.initials: Y
authors.lastname: Eguchi
authors.forename: Nobuyasu
authors.initials: N
authors.lastname: Ochiai
authors.forename: Shunji
authors.initials: S
authors.lastname: Kishida
authors.forename: Junichi
authors.initials: J
authors.lastname: Nakamura
authors.forename: Masashi
authors.initials: M
authors.lastname: Takaso
authors.forename: Tetsuhiro
authors.initials: T
authors.lastname: Ishikawa
authors.forename: Gen
authors.initials: G
authors.lastname: Arai
authors.forename: Masayuki
authors.initials: M
authors.lastname: Miyagi
authors.forename: Hiroto
authors.initials: H
authors.lastname: Kamoda
authors.forename: Yasuchika
authors.initials: Y
authors.lastname: Aoki
authors.forename: Ryo
authors.initials: R
authors.lastname: Hiwatari
authors.forename: Jun
authors.initials: J
authors.lastname: Kakizaki
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Kunishi
authors.forename: Motoaki
authors.initials: M
authors.lastname: Kono
authors.forename: Takane
authors.initials: T
authors.lastname: Suzuki
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Toyone
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Takahashi
authors.forename: Kazuki
authors.initials: K
authors.lastname: Kuniyoshi
authors.forename: Seiji
authors.initials: S
authors.lastname: Ohtori
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D015415:Biomarkers / Q000378:metabolism; D004195:Disease Models, Animal; D008297:Male; D009479:Neuropeptides / Q000378:metabolism*; D010146:Pain / Q000175:diagnosis / Q000378:metabolism* / Q000503:physiopathology*; D010147:Pain Measurement / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012585:Sciatica / Q000175:diagnosis / Q000378:metabolism* / Q000503:physiopathology*
chemical_list: D015415:Biomarkers; D009479:Neuropeptides