The main neuropeptides in peripheral nerve ganglia, which can anterogradely transmit nociceptive information to the central nervous system are substance P and calcitonin gene-related peptide.
In a study by Dr. Changma Fu and co-workers from First Hospital of Anhui Medical University in China, a model of sciatic nerve defect was prepared by dissecting the sciatic nerve at the middle, left femur in female Sprague Dawley rats. The two ends of the nerve were encased in a silica gel tube. L5 dorsal root ganglia were harvested 7, 14 and 28 days post sciatic nerve injury for immunohistochemical staining.
Results showed that substance P and calcitonin gene-related peptide expression increased significantly in dorsal root ganglion of rats with sciatic nerve injury. This increase peaked at 7 days, declined at 14 days, and reduced to normal levels by 28 days post injury. These findings published in the Neural Regeneration Research (Vol. 8, No. 33, 2013) suggest that these neuropeptides may possibly serve as an index for evaluating early peripheral nerve injury.