Vasoactive intestinal peptide and substance P-like immunoreactivities in the enteric nervous system of the pig correlate with the severity of pathological changes induced by Schistosoma japonicum

Limited studies have shown that in intestinal schistosomosis, the enteric n ervous tissue becomes inflamed, disrupted and destroyed by granulomas and p eptides, amines and neurofilaments contents are altered, Therefore, immunor eactivities of vasoactive intestinal peptide and substance P were correlate d to pathological lesions in the large intestine from pigs infected with Sc histosoma japonicum. Ganglia situated within or near granulomas showed gang lionitis, and necrosis of neurons as well as infiltration by eosinophils, m ast cells, lymphocytes, plasma cells, neutrophils and macrophages. The inne r submucous and mucous plexuses were the most damaged. In all categories of inflamed areas, the vasoactive intestinal peptide-like immunoreactive was reduced in all plexuses whereas, that of substance P was increased both in the enteric nerve plexuses and enterochromaffin cells in lightly, moderatel y and severely inflamed tissues. However, both peptides were highly diminis hed or absent in very severe lesions and areas surrounding schistosome eggs and mature worms laying eggs in the submucosal veins. The alterations of t he levels of vasoactive intestinal peptide and substance P were correlated with severity of inflammation. Our observations show alterations of vasoact ive intestinal peptide and substance P contents in the local microenvironme nt in the vasoactive intestinal peptide- and substance P-mediated reflex pa thways which regulate intestinal motility, epithelial transport and modulat e immunity. These changes could cause alterations in bowel motility, electr olyte and fluid secretion, vascular and immune functions during S. japonicu m infections in the pig. This may, therefore, partly play a role in the pat hobiology of migration and egress of schistosome eggs as well as influence trapping of eggs in granulomas, and account for diarrhoea, loss of body wei ght and failure to thrive, which are recorded in schistosomosis. (C) 2001 A ustralian Society for Parasitology Inc. Published by Elsevier Science Ltd. All rights reserved.