Pituitary adenylate cyclase activating polypeptide-immunoreactivity in human spinal cord and dorsal root ganglia

Immunohistochemical studies using an antibody against pituitary adenylate cyclase activating polypeptide-38 (PACAP) were performed on spinal cords and dorsal root ganglia harvested from two human cadavers. PACAP-like immunoreactivity (PACAP-LI) was detected in nerve fibers of the superficial layers of the dorsal horn, a few of which extended into the deeper laminae and as far as the ventral horn. At the thoracic segments, additional PACAP-LI nerve fibers were seen in the lateral funiculus projecting into the intermediolateral cell column. Dorsal root ganglia contained numerous PACAP-LI cell bodies of varying intensity. As a control, immunoreactivity to calcitonin gene-related peptide (CGRP) and substance P(SP) was also studied and found to be in nerve fibers of the substantia gelatinosa of the dorsal horn and in dorsal root ganglion cells. These results show that the pattern of distribution of PACAP-LI in the human spinal cord and dorsal root ganglia is similar to that of rodents and further suggest that PACAP may participate in sensory and autonomic functions.