title: Evidence for a parasite-mediated inhibition of abomasal acid secretion in sheep infected with Ostertagia leptospicularis.
abstract: The acid secretory capacity of the abomasal mucosa was studied in sheep experimentally infected with Ostertagia leptospicularis. The acidity of the abomasal contents, permanently recorded by a pH probe located inside the abomasum, decreased markedly to mean levels between pH 5 and 6. Subcutaneous administration of histamine or carbachol successfully stimulated acid secretion (pH 3.4). The results indicate that the abomasal mucosa harboured a population of functional parietal cells which were also identified immunohistochemically (H(+)/K(+)-ATPase). Ultrastructural investigation before stimulation revealed that the majority of these cells was in a resting state. Despite high serum gastrin levels, the acid secretion was blocked either at the level of the parietal cell or the enterochromaffin-like cell by an unknown factor, possibly mediated by the parasites. This is the first report of a parietal cell dysfunction associated with a nematode infection in the abomasum. It is suggested that the parasites induce changes in their environment which favour their survival and/or increase their reproduction.
authors.affiliation: Institute of Parasitology, Clinic of Large Animal Surgery, University of Zürich, Switzerland. hhertzbe@vetparas.unizh.ch
authors.forename: H
authors.initials: H
authors.lastname: Hertzberg
authors.forename: F
authors.initials: F
authors.lastname: Guscetti
authors.forename: C
authors.initials: C
authors.lastname: Lischer
authors.forename: L
authors.initials: L
authors.lastname: Kohler
authors.forename: R
authors.initials: R
authors.lastname: Neiger
authors.forename: J
authors.initials: J
authors.lastname: Eckert
mesh_terms: D000018:Abomasum / Q000378:metabolism* / Q000469:parasitology / Q000648:ultrastructure; D000818:Animals; D005243:Feces / Q000469:parasitology; D005744:Gastric Acid / Q000378:metabolism*; D005755:Gastrins / Q000097:blood; D005773:Gastroscopy / Q000662:veterinary; D006863:Hydrogen-Ion Concentration; D007150:Immunohistochemistry; D008854:Microscopy, Electron / Q000662:veterinary; D010028:Ostertagia / Q000502:physiology*; D010029:Ostertagiasis / Q000469:parasitology / Q000503:physiopathology / Q000662:veterinary*; D010295:Parietal Cells, Gastric / Q000378:metabolism / Q000469:parasitology / Q000648:ultrastructure; D020116:Pepsinogen A / Q000097:blood; D012756:Sheep; D012757:Sheep Diseases / Q000469:parasitology* / Q000503:physiopathology*
chemical_list: D005755:Gastrins; D020116:Pepsinogen A