Evidence for coexistence of choline acetyltransferase (ChAT)- and calcitonin gene-related peptide (CGRP)-immunoreactivity in the thoracolumbar and sacral spinal cord neurons of the pig.

Previous immunocytochemical studies provided conflicting data concerning occurrence of the CGRP-immunoreactive neuronal cell bodies in the porcine spinal cord. In the present study, we have investigated expression of the CGRP and its possible coexpression with ChAT in the gray matter of the thoracic, lumbar and sacral spinal cord of the pig. Our study revealed a large number of CGRP-immunoreactive cells in the motor nucleus of the ventral horn, and less and singe perikarya intermediolateral and intermediomedial nuclei, respectively. Double staining immunocytochemistry, depending on the cross-section level, disclosed the highest ChAT/CGRP colocalization subsequently in the motor nucleus of the ventral horn, then in the intermediolateral and intermediomedial nucleus. Our data provide morphological evidence confirming expression of CGRP in the porcine spinal nuclei while its coexpression in cholinergic neurons suggests that CGRP may play a role in modulation of the spinal cholinergic transmission.