Neural somatostatin, vasoactive intestinal polypeptide and substance P in canine and human jejunum

The distribution and co-localization of substance P immunoreactivity (SP-IR), somatostatin-IR (SS-IR) and vasoactive intestinal peptide-IR (VIP-IR) have been determined in canine and human jejunum by immunocytochemistry (ICC). Immunostaining with an antibody to protein gene product 9.5 revealed fewer neuronal cell bodies in the submucosal ganglion of human than in canine intestine. Double immunostaining demonstrated that SP-IR and SS-IR were always co-localized in human but never in canine submucosal neurons. In both species, VIP-IR was present in a separate population of neurons. In canine submucosal ganglia, each peptide represented approximately one-third of the neurons while the proportions of VIP and SP/SS-containing neurons in human were 40% and 42%, respectively. These results provide neuroanatomical evidence for different functions of neural SP and SS in canine and human jejunum.