Substance P and neurotensin are up-regulated in the lumbar spinal cord of animals with neuropathic pain.

Many neuropeptides have been shown to be up-regulated in response to pain. The purpose of this study was to identify pain-related peptides in a rat model of neuropathic pain induced by sciatic nerve cuff implantation. Rats were tested for touch sensitivity prior to and 7 days following cuff implantation or sham surgeries. The lumbar spinal cord was removed on the 8th day post-surgery and the lumbar enlargement was processed for the detection of selected peptides using time-of-flight mass spectrometry. Only substance P (MW 1346.74) and neurotensin (MW 1673.0) were detected in the lumbar spinal cord of animals with mechanical allodynia (P < 0.01) following innocuous tactile stimulation of the affected hind paw. Therefore, substance P and neurotensin may be target candidates for the understanding and treatment of neuropathic pain.