The expression of calcitonin gene-related peptide in dorsal horn neurons of the mouse lumbar spinal cord.

Using immunohistochemistry and in situ hybridization the expression of calcitonin gene-related peptide (CGRP) was studied in the mouse spinal cord under normal conditions and after unilateral rhizotomy and after local colchicine treatment. Under normal conditions a dense plexus of CGRP-immunoreactive (IR) fibres was observed in the superfical layers of dorsal horns with lower numbers of fibers in deeper laminae. Seven days after unilateral rhizotomy, there was a marked reduction of CGRP-IR fibres in the ipsilateral superfical layers and distinctly CGRP-IR neurons could be detected in the ipsilateral lamina III. CGRP mRNA-positive neurons were observed in lamina III in both the ipsilateral and contralateral dorsal horn. Colchicine treatment did not markedly increase the number of CGRP-IR neurons. The results suggest that CGRP is synthesized in local dorsal horn neurons of the mouse, and these neurons presumably participate in sensory processing.