Changes in substance P and somatostatin in the spinal cord after traumatic spinal injury in the rat.

Immunoreactive substance P (SPI) and somatostatin (SOMI) are found in spinal cord but their physiological roles remain speculative. Several classes of neuropeptides, including endogenous opioids and thyrotropin-releasing hormone (TRH), have been implicated in the pathogenesis or recovery from spinal cord injury. In the present studies, changes in SPI and SOMI were examined in the spinal cord after traumatic injury in the rat. Both peptides showed time-dependent, localized decreases at the injury site, which were statistically related to the degree of post-traumatic neurological dysfunction. Such changes differ from those of a number of other peptides after spinal injury and suggest that substance P and/or somatostatin may play a role in the secondary pathophysiological responses which follow trauma to the spinal cord.