Application of nucleus pulposus to nerve root generates radicular pain. We demonstrated that these animals showed allodynia for 2 weeks, and cyclooxygenase-2 (COX-2) immunoreactivities were up-regulated in the spinal dorsal horn. COX-2 immunoreactivities were shown in neurons; however, they were not in astrocytes. Intrathecal administration of an antibody to COX-2 decreased allodynia. Our results suggest that COX-2 in spinal cord might be a target for treatment of patients with nerve root pain caused by lumbar disk herniation.
Perspective: Neural COX-2 might mediate nerve root pain in the spinal cord caused by lumbar disk herniation in rats.