Anatomical evidence that the uninjured adjacent L4 nerve plays a significant role in the development of peripheral neuropathic pain after L5 spinal nerve ligation in rats.

Rats develop hyperalgesia and allodynia in the hind paw after L5 spinal nerve ligation. Phosphorylated extracellular regulated kinase (pERK) was used as a pain marker to investigate the potential role of adjacent uninjured L4 nerve in the development of heat hyperalgesia after L5 nerve injury. Left L5 nerve was ligated and sectioned in rats.