DISTRIBUTION OF 2 VIP-RELATED PEPTIDES, HELOSPECTIN AND PITUITARY ADENYLATE-CYCLASE ACTIVATING PEPTIDE (PACAP), IN THE HUMAN UPPER RESPIRATORY SYSTEM

Helospectin (HS) and pituitary adenylate cyclase activating peptide (P ACAP) are newly discovered peptides isolated from the salivary gland v enom of the lizard Heloderma horridum and the ovine hypothalamus, resp ectively. They show chemical similarities to vasoactive intestinal pol ypeptide (VIP), appear to have similar functions and are present in gu t, brain, lung, male and female genitourinary tract. In the present st udy, the distribution of the helospectin and PACAP-27 in the human upp er respiratory system was investigated using indirect immunofluorescen ce and electron-microscopical ABC-pre-embedding methods, Immunohistoch emistry revealed helospectin-like (HS-LI) and PACAP-like (PACAP-LI) im munoreactivity in nerve fibers in human nasal, the larynx (vocal cord, ventricular fold, epiglottis), the tongue and the soft palate mucosa. Helospectin-LI and PACAP-LI containing nerve fibers were mainly found in close association to blood vessels and glandular structures. Coloc alization studies carried out by application of double immunofluoresce nce showed that HS and/(or) PACAP-LI coexist with VIP in apparently th e same nerve fibers in the upper respiratory system, although single n erve fibers seem to exclusively express helospectin. The localization patterns of helospectin and PACAP-LI in the human upper respiratory sy stem suggests their possible involvement in the regulation of secretor y activities and local blood flow.