CGRP expression increases in the ventral horn rostral to spinal cord transection

Rats underwent spinal cord transection (SCT) at the mid-thoracic level, and calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) was analysed in the ventral horn rostral and caudal to the injury. CGRP expression decreased in motor neurones caudal to the lesion, as previously described. Rostral to the transection, however, the area of CGRP-LI increased in the ventral horn 1 and 2 weeks following SCT, although the number of neurones expressing CGRP did not differ from controls. Immunofluorescent fibres were seen in the ventral horn rostral to the lesion only after SCT. Thus, we report the novel observation that CGRP expression in motor neurones is upregulated rostral to a spinal cord lesion, perhaps due to an imbalance of descending and intraspinal inputs.