IMMUNOCYTOCHEMICAL DETECTION OF VASOACTIVE INTESTINAL PEPTIDE-LIKE AND PEPTIDE HISTIDINE ISOLEUCINE-LIKE PEPTIDES IN THE NERVOUS-SYSTEM ANDTHE EXCRETORY SYSTEM OF ADULT NIPPOSTRONGYLUS-BRASILIENSIS

Vasoactive intestinal peptide-like and peptide histidine isoleucine-li ke immunoreactivities were detected in the excretory duct of adult mal e and female Nippostrongylus brasiliensis, thus indicating the source of these two physiologically active peptides previously isolated from the excretory/secretory products of adult N. brasiliensis. In the nerv ous system immunoreactivity to both these peptides was confined to fem ales and was found in the neurons of the ovijector associated ganglion . This is consistent with co-synthesis of vasoative intestinal peptide -like and peptide histidine isoleucine-like peptides which has also be en shown to occur in all mammalian vasoactive intestinal peptid-ergic neurons studied to date. However, in addition to this, and in common t o some previous studies on helminth vasoactive intestinal peptide and peptide histidine isoleucine immunoreactivities, co-synthesis of the p eptides was not indicated in a pair of branched neurons which projecte d posteriorly and peripherally from the ganglion associated with the o vijector of females and which terminated in two pairs of ganglia also exhibiting vasoactive intestinal peptide-like immunoreactivity only. T he position of these ganglia indicated that they innervate muscles clo se to the body wall and may be reponsible for the muscular contraction s required for expulsion of eggs from female Nippostrongylus brasilien sis. This is also the first study to successfully detect these peptide s in the excretory system of gastrointestinal nematodes. (C) 1998 Aust ralian Society for Parasitology. Published by Elsevier Science Ltd.