title: Preemptive perineural bupivacaine attenuates the maintenance of mechanical and cold allodynia in a rat spinal nerve ligation model.
abstract: BACKGROUND
  Neuropathic pain is evasive to treat once developed, however evidence suggests that local administration of anesthetics near the time of injury reduces the development of neuropathic pain. As abnormal electrical signaling in the damaged nerve contributes to the initiation and maintenance of neuropathic pain, local administration of anesthetics prior to injury may reduce its development. We hypothesized that local treatment with bupivacaine prior to nerve injury in a rat model of spinal nerve ligation (SNL) would attenuate the initiation and/or maintenance of neuropathic pain behaviors.
  
  
  METHODS
  On the day prior to SNL, baseline measures of pre-injury mechanical, thermal, and/or cold sensitivity were recorded in adult male Sprague-Dawley rats. Immediately prior to SNL or sham treatment, the right L5 nerve was perineurally bathed in either 0.05 mL bupivacaine (0.5 %) or sterile saline (0.9 %) for 30 min. Mechanical allodynia, thermal hyperalgesia, and/or cold allodynia were then examined at 3, 7, 10, 14 and 21 days following SNL.
  
  
  RESULTS
  Rats exhibited both mechanical and cold allodynia, but not thermal hyperalgesia, within 3 days and up to 21 days post-SNL. No significant pain behaviors were observed in sham controls. Preemptive local bupivacaine significantly attenuated both mechanical and cold allodynia as early as 10 days following SNL compared to saline controls and were not significantly different from sham controls.
  
  
  CONCLUSIONS
  These data indicate that local treatment with bupivacaine prior to surgical manipulations that are known to cause nerve damage may protect against the maintenance of chronic neuropathic pain.
authors.affiliation: Pain Management Research Area, United States Army Institute of Surgical Research, Fort Sam Houston, TX, USA.
authors.forename: John L
authors.initials: JL
authors.lastname: Clifford
authors.affiliation: Pain Management Research Area, United States Army Institute of Surgical Research, Fort Sam Houston, TX, USA.
authors.forename: Alberto
authors.initials: A
authors.lastname: Mares
authors.affiliation: Pain Management Research Area, United States Army Institute of Surgical Research, Fort Sam Houston, TX, USA.
authors.forename: Jacob
authors.initials: J
authors.lastname: Hansen
authors.affiliation: Department of Biology, Texas Woman's University, PO Box 425799, Denton, TX, 76204-5799, USA. daveritt@twu.edu.
authors.forename: Dayna L
authors.initials: DL
authors.lastname: Averitt
mesh_terms: D000779:Anesthetics, Local / Q000008:administration & dosage*; D000818:Animals; D002045:Bupivacaine / Q000008:administration & dosage*; D003080:Cold Temperature / Q000009:adverse effects; D006930:Hyperalgesia / Q000188:drug therapy* / Q000473:pathology; D008026:Ligation; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013127:Spinal Nerves / Q000187:drug effects* / Q000293:injuries*
chemical_list: D000779:Anesthetics, Local; D002045:Bupivacaine