Calcitonin gene-related peptide (CGRP) in the regulation of salivary secretion.

The occurrence of calcitonin gene-related peptide (CGRP) in nerves in the submandibular gland was studied by using indirect immunofluorescence technique. The functional significance of CGRP was further evaluated by using an in vitro method for demonstration of protein and peroxidase secretion. CGRP-immunoreactive nerve fibers were observed mainly around large ducts and around blood vessels in the stromal part of submandibular gland. A moderate amount of CGRP-immunoreactivity were seen around the secretory acini as well. In vitro, CGRP increased significantly total protein and peroxidase secretion. SDS gel electrophoresis revealed 20 different protein bands both in normal and stimulated samples. After CGRP-stimulation 13 out of these 20 bands showed more intensive staining in this semi-quantitative analysis. The present results demonstrate that the secretory elements of the rat submandibular gland are innervated by CGRP-IR nerve fibers and that CGRP has a significant effect on protein secretion in vitro. Thus our results support the view that CGRP has a direct stimulatory effect on salivary secretion.