title: Swing time ratio, a new parameter of gait disturbance, for the evaluation of the severity of neuropathic pain in a rat model of partial sciatic nerve ligation.
abstract: BACKGROUND
  Dynamic weight bearing tests are used to evaluate the chronic pain severity in animal models of nociceptive pain (such as osteoarthritis); however, common tests frequently fail to collect the characteristics of neuropathic pain such as allodynia, because surgical intervention which is sometimes required to establish the models causes both nociceptive and neuropathic pain.
  
  
  METHODS
  In this study, we used rats with partial sciatic nerve ligation (PSL) as the neuropathic and chronic pain model. To assess the severity of pain by gait disturbance, we applied automatic analysis on walking function using the GAIT® system. The system employs a novel index of abnormal step cycles, the swing time ratio (STR), of laboratory animals. Data were compared to those obtained with conventional tests, including a von Frey test and a hot plate test. Finally, we analyzed recovery of walking function after single or repeated administration of pregabalin.
  
  
  RESULTS
  By using rats with PSL, we confirmed that results obtained by the GAIT® system were comparable to those obtained by both von Frey tests and hot plate tests. Single administration of pregabalin transiently improved STR, on the other hand, repeated pregabalin treatment showed lasting STR recovery.
  
  
  CONCLUSIONS
  STR is sensitive to claudication of rats with PSL, providing a new scale to evaluate neuropathic pain in addition to conventional tests. Moreover, STR analysis enables us to evaluate walking function of animal models after neuropathic injury, which is quite important to judge the effectiveness of new treatments and analgesics.
authors.affiliation: Cooperative Major in Advanced Health Science, Graduate School of Bio-Applications and System Engineering, Japan.
authors.forename: Kenshiro
authors.initials: K
authors.lastname: Matsuda
authors.affiliation: Laboratory of Physiology II, Department of Veterinary Medicine, School of Veterinary Medicine, Azabu University, Kanagawa, Japan.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Orito
authors.affiliation: Laboratory of Veterinary Molecular Pathology and Therapeutics, Division of Animal Life Science, Institute of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Amagai
authors.affiliation: Cooperative Major in Advanced Health Science, Graduate School of Bio-Applications and System Engineering, Japan.
authors.forename: Hyosun
authors.initials: H
authors.lastname: Jang
authors.affiliation: Cooperative Major in Advanced Health Science, Graduate School of Bio-Applications and System Engineering, Japan; Laboratory of Veterinary Molecular Pathology and Therapeutics, Division of Animal Life Science, Institute of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Matsuda
authors.affiliation: Cooperative Major in Advanced Health Science, Graduate School of Bio-Applications and System Engineering, Japan; Laboratory of Comparative Animal Medicine, Division of Animal Life Science, Institute of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan. Electronic address: akane@cc.tuat.ac.jp.
authors.forename: Akane
authors.initials: A
authors.lastname: Tanaka
mesh_terms: D000818:Animals; D005684:Gait / Q000187:drug effects / Q000502:physiology*; D008026:Ligation / Q000379:methods; D008297:Male; D009437:Neuralgia / Q000188:drug therapy / Q000503:physiopathology*; D010147:Pain Measurement / Q000379:methods; D017288:Pain Threshold / Q000187:drug effects / Q000502:physiology; D000069583:Pregabalin / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012584:Sciatic Nerve / Q000187:drug effects / Q000503:physiopathology* / Q000601:surgery*
chemical_list: D000069583:Pregabalin
keywords: Animal model; GAIT® system; Gait disturbance; Neuropathic pain; Partial sciatic nerve ligation; Pregabalin; Swing time ratio