Distribution and co-localization of immunoreactive helospectin with vasoactive intestinal polypeptide and peptide histidine methionine in human nasal mucosa, soft palate and larynx.

Regulatory peptide immunoreactivities reported in the upper respiratory system of man include vasoactive intestinal polypeptide (VIP) and peptide histidine methionine (PHM), which are co-localized in a network of fine varicose nerve fibers. The present study was undertaken to examine the possible occurrence and distribution of the recently described VIP-like peptide helospectin. Double immunofluorescence labelling showed that helospectin is co-localized with VIP and PHM. In addition to nerve fibers containing all three peptides, scattered nerve fibers were detected that were only immunoreactive to helospectin but not to VIP and/or PHM. The distribution of helospectin/VIP/PHM immunoreactive nerve fibers around blood vessels and in close relationship to seromucous glands indicates their possible involvement in the regulation of blood flow and secretion.