Distribution of VIP receptors in the human submandibular gland: an immunohistochemical study.

Distribution of vasoactive intestinal polypeptide (VIP)-immunoreactive nerve fibers and VIP-receptor (VIP-R)-immunoreactive sites in the human submandibular gland were examined by the peroxidase-antiperoxidase method using the specimens taken from patients that had not received radiotherapy. VIP-immunoreactive fibers were found around both serous and mucous acini, the duct system, and those around the mucous acini were more numerous than those around the serous acini. VIP-R immunoreactivity was restricted to the mucous acini and the intercalated duct segment. The serous acini, striated duct, and excretory ducts lacked VIP-R immunoreactivity. These findings suggest that the mucous acinar cells contain VIP-R, and that VIP-R-mediated VIP action is involved in regulating synthesis of viscous saliva and its release.