title: A new animal model of trigeminal neuralgia produced by administration of cobra venom to the infraorbital nerve in the rat.
abstract: BACKGROUND
  Understanding the mechanism of trigeminal neuralgia may be elucidated by developing laboratory animal models that closely mimic the features of this specific type of neuropathic pain. We have developed an experimental animal model for trigeminal neuralgia using a technique of injecting cobra venom into the infraorbital nerve (ION) trunk.
  
  
  METHODS
  Male Sprague-Dawley rats were subjected to the administration of cobra venom or saline into the ION trunk. Mechanical stimuli were applied to the ION territory in consecutive days after surgery. Mechanical thresholds were measured over a 90-day period on the bilateral facial region. Vascular permeability in the ION territory was measured using Evans blue dye.
  
  
  RESULTS
  The cobra venom-treated rats developed mechanical allodynia 3 days after surgery that lasted for 60 days postoperatively at the ipsilateral side. The mechanical thresholds of the contralateral ION territory also showed a profound decrease but were sustained for only approximately 30 days. There was no change of mechanical thresholds in the control groups. The extravasation of Evans blue increased significantly in the skin after administration of cobra venom to the ION compared with control rats (P < 0.05).
  
  
  CONCLUSIONS
  The cobra venom model may provide a reasonable model for investigating the mechanism of trigeminal neuropathic pain.
authors.affiliation: Department of Anesthesiology, Central South University Xiangya Hospital, Changsha, China. anjianxiong@yahoo.co
authors.forename: Jian-Xiong
authors.initials: JX
authors.lastname: An
authors.forename: Ying
authors.initials: Y
authors.lastname: He
authors.forename: Xiao-Yan
authors.initials: XY
authors.lastname: Qian
authors.forename: Jian-Ping
authors.initials: JP
authors.lastname: Wu
authors.forename: Yi-Kuan
authors.initials: YK
authors.lastname: Xie
authors.forename: Qu-Lian
authors.initials: QL
authors.lastname: Guo
authors.forename: John P
authors.initials: JP
authors.lastname: Williams
authors.forename: Doris K
authors.initials: DK
authors.lastname: Cope
mesh_terms: D000818:Animals; D002199:Capillary Permeability; D004396:Coloring Agents / Q000378:metabolism; D004195:Disease Models, Animal; D004546:Elapid Venoms; D005070:Evans Blue / Q000378:metabolism; D006930:Hyperalgesia / Q000139:chemically induced* / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D009915:Orbit / Q000098:blood supply / Q000294:innervation*; D010147:Pain Measurement; D017288:Pain Threshold; D051381:Rats; D017207:Rats, Sprague-Dawley; D012867:Skin / Q000098:blood supply; D013997:Time Factors; D014276:Trigeminal Nerve / Q000378:metabolism / Q000503:physiopathology*; D014277:Trigeminal Neuralgia / Q000139:chemically induced* / Q000378:metabolism / Q000503:physiopathology
chemical_list: D004396:Coloring Agents; D004546:Elapid Venoms; D005070:Evans Blue