Differential expression of c-fos and c-jun in two regions of the rat spinal cord following noxious colorectal distention.

Thoracolumbar and lumbosacral spinal segments that receive afferent input from the descending colon and rectum were stained immunocytochemically for c-Fos- and c-Jun-like proteins following repetitive, noxious colorectal distention (CRD). Noxious CRD (80 mmHg) resulted in significantly more c-Fos- and c-Jun-like immunoreactivity in the sacral dorsal horn than in the thoracic dorsal horn. In both regions of the spinal cord the increase in c-Fos-like immunoreactivity was at least twice that of c-Jun-like immunoreactivity. Basal levels of c-Jun but not c-Fos were observed in the thoracic intermediolateral nucleus (IML) and the sacral parasympathetic nucleus (SPN). Noxious CRD induced both c-Fos and c-Jun in the SPN, but not the IML.