Changes of Immunoreactivity for CGRP and SP according to the Distance between the DRG and Injury Site of Neuropathic Rat

J Korean Assoc EMG Electrodiagn Med 2000;2(1):55-64.
Published online May 9, 2000.

Abstract

Objectives : Peripheral nerve injury sometimes leads to neuropathic pain and depletion of calcitonin gene related-peptide (CGRP) and substance P (SP) in the spinal cord. This study was performed to see whether the distribution of immunoreactivity for CGRP and SP in dorsal horn and dorsal root ganglia (DRG) was related to the distance between DRG and injury site. Methods : We compared two groups of rats; one group was subjected to unilateral inferior and superior caudal trunk transections at the level between the S3 and S4 spinal nerves (S34 group) and the other group at the levels between S1 and S2, between S2 and S3, and between S3 and S4 spinal nerve (S123 group). Results : The immunoreactive area of SP and CGRP in the S1 dorsal horn was smaller in the S123 group than in the S34 group, whereas that in the S3 dorsal horn was not significantly different between the two groups. The number of SP- immunoreactive DRG cells decreased as compared to the sham group’s in all DRGs of experimental groups except the S1 DRG of the S34 group. Conclusion : This study shows that the amounts of SP and CGRP in the dorsal horn and DRG following neuropathic injury inversely decrease according to the distance between the DRG and injury site.

Key Words: Peripheral nerve injury, Substance P, Calcitonin gene-related peptide