Neuropathic pain models

Spinal nerve ligation (SNL) in rats and mice was performed as previously reported [15;33;45]. Briefly, a midline skin incision was made on the lower back. The sixth lumbar transverse process on rats or fifth lumbar transverse process on mice was identified, and then was separated from its muscle attachments. The underlying fifth lumbar spinal nerve in rats or fourth lumbar spinal nerve in mice was isolated and ligated with a 4-0 silk suture in rats or 7-0 silk suture in mice. The ligated nerve was then transected at the distal end. Sham-operated groups received identical surgical procedures only exposing the nerves without ligation and transection. The surgical field was then irrigated with sterile saline and the skin incision was closed with wound clips.