Comparative proteomic analysis of the rat spinal cord in inflammatory and neuropathic pain models

Pathological pain associated either with peripheral tissue damage and inflammation (inflammatory pain) or peripheral nerve injury (neuropathic pain) is characterized by persistent pain hypersensitivity. This hypersensitivity is believed to be mediated by sensitization of nociceptors and spinal dorsal horn neurons leading to hyperalgesia and allodynia. Changes of protein expression and/or phosphorylation are known to contribute to the development of this hyperexcitability of the nociceptive system. In the present study we analyzed protein patterns in the spinal cord following paw inflammation or sciatic nerve injury using two-dimensional (2D) gel electrophoresis combined with MALDI-TOF mass spectrometry. 2D-PAGE revealed nine and five regulated proteins following paw inflammation and sciatic nerve damage, respectively. These regulated proteins had not been identified previously with other methods. There was no overlap of regulated proteins between models except for the small heat shock protein alpha-crystallin, which was decreased in both models. In conclusion, this study illustrates that employment of the proteomic 2D-PAGE approach allows for identification of novel regulated proteins that may be involved in the central sensitization and possibly manifestation of chronic pain.