HELOSPECTIN AND PITUITARY ADENYLATE-CYCLASE ACTIVATING POLYPEPTIDE INTHE HUMAN VAGINA

Helospectin and pituitary adenylate cyclase activating polypeptide (PA CAP), both recently isolated from the poisonous saliva of the American lizard or from ovine hypothalamus respectively, belong to the same pe ptide family as vasoactive intestinal polypeptide (VIP), peptide histi dine methionine (PHM) and glucagon. In the present study, occurrence a nd distribution patterns of nerve fibers containing helospectin- and P ACAP-like immunoreactivity in the human vagina were investigated by im munohistochemistry. Double immunofluorescent labeling showed that helo spectin or PACAP are coexpressed with VIP and PHM within subpopulation s of VIP-immunoreactive nerve fibers. Nervous structures containing he lospectin and VIP were particularly numerous in the internal mucous li ning of the vagina and in free epithelial nerve endings, and an abunda nt network of nerve fibers surrounding blood vessels was detected. Ner ve fibers co-expressing PACAP and VIP were more numerous than those ex pressing helospectin and VIP and were mainly found in close associatio n with blood vessels as well as beneath and within the epithelium, Due to the lack of non-rabbit helospectin or PACAP antibodies, possible c o-localizations between these two peptides could not be investigated a t this time. The localizations demonstrated suggest possible roles of the two peptides in the regulation of local blood flow and lubrication of the vagina.