DIFFERENTIAL EXPRESSION OF C-FOS AND C-JUN IN 2 REGIONS OF THE RAT SPINAL-CORD FOLLOWING NOXIOUS COLORECTAL DISTENSION

Thoracolumbar and lumbosacral spinal segments that receive afferent in put from the descending colon and rectum were stained immunocytochemic ally for c-Fos- and c-Jun-like proteins following repetitive, noxious colorectal distention (CRD). Noxious CRD (80 mmHg) resulted in signifi cantly more c-Fos- and c-Jun-like immunoreactivity in the sacral dorsa l 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 t hat of c-Jun-like immunoreactivity. Basal levels of c-Jun but not c-Fo s were observed in the thoracic intermediolateral nucleus (IML) and th e sacral parasympathetic nucleus (SPN). Noxious CRD induced both c-Fos and c-Jun in the SPN, but not the IML.