Model of intestinal amebiasis: structural and functional lesions to the rabbit colon mucosa by Entamoeba histolytica lysates.

Although the events occurring during the initial interaction of E. histolytica trophozoites with the mucosa of the large intestine probably determine the invasion by the parasites, an appropriate experimental model does not exist. To develop such a model we used full-thickness rabbit colon preparations (0.28 cm2) mounted in Ussing-type chambers. Untreated preparations had electrophysiological properties (potential difference, short-circuit current and electrical resistance) similar in magnitude and duration to those reported for stripped colonic mucosa. Exposure to E. histolytica trophozoite lysates for up to 80 min produced dose-dependent lesions in the colon, consisting of: (a) increased decay rates for potential difference, short-circuit current and transmural resistance, and (b) mucosal lesions involving vacuolation at the bases and shortening of epithelial cells, loss of intercellular junctions, destruction of microvilli, and necrosis of interglandular epithelial zones. The specificity and speed of the electrophysiologic effects and their correlation with the microscopic lesions suggest that this new model will help to understand the initial pathogenic events of intestinal amebiasis.