IMMUNOCYTOCHEMICAL CORRELATION OF PEPTIDES AND TYROSINE-HYDROXYLASE IN NERVE-FIBERS OF THE HUMAN PAROTID-GLAND

The peptidergic innervation of parenchymal and vascular components in the human parotid gland was investigated by double-labelling fluoresce nce. Peptide immunoreactivity in nerve fibres was correlated with the presence of tyrosine hydroxylase (TK). By light microscopy, acinar inn ervation consisted of fibres with the combinations neuropeptide Y (NPY )/TH and NPY/vasoactive intestinal polypeptide (VIP). Some fibres were solely NPY, TH or VIP immunoreactive. Rarely, substance P (SP)/calcit onin gene-related (CGRP)-immunolabelled fibres were associated with ac ini. Intercalated ducts were often approached by NPY/TH- and VIP-conta ining fibres. VIP innervation of excretory ducts was sparse. Intralobu lar and intralobar excretory ducts, in addition to NPY and TH, reveale d CGRP and CGRP/SP innervation, whereas nerve fibres on interlobar exc retory ducts very rarely contained NPY and none of the other mediators . Vascular innervation consisted of NPY/TH and SP/CGRP fibres; in a fe w fibres SP was colocalized with leu-enkephalin. Large arteries were e ncircled by some VIP-positive fibres. The findings suggest a specific participation of neuropeptides and of peptide combinations in the regu lation of parotid exocrine function.