• Michiaki Mukai, Yoshihiro Sakuma, Miyako Suzuki, Sumihisa Orita, Kazuyo Yamauchi, Gen Inoue, Yasuchika Aoki, Tetsuhiro Ishikawa, Masayuki Miyagi, Hiroto Kamoda, Gou Kubota, Yasuhiro Oikawa, Kazuhide Inage, Takeshi Sainoh, Jun Sato, Junichi Nakamura, Masashi Takaso, Tomoaki Toyone, Kazuhisa Takahashi, and Seiji Ohtori.
• Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan.
• Eur Spine J. 2014 Feb 1; 23 (2): 463-8.

PurposeThe 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.MethodsRats 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.ResultsMechanical 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).ConclusionsOur 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.

22 keywords...

hide…