Effects of experimental hemosiderosis on intestinal morphology, permeability, and tissue iron content.

Effects of iron overload on intestinal function and structure are unknown and were, therefore, investigated. Sprague-Dawley rats were randomized into an iron-overloaded group, which received a single subcutaneous injection of 1.2 g/kg elemental iron-dextran complex, and placebo-treated pair-fed controls. Animals were studied after a 10-month observation period. Intestinal permeability was assessed by measuring the urinary excretion of lactulose, rhamnose, and mannitol after oral administration. In addition, tissue nonheme iron content was measured, and histologic examination and morphometric measurements were carried out. The chronic iron-overloaded group showed a significant increase in intestine tissue iron content and stainable iron in the submucosa and muscularis propria and adipose tissue of the small intestine and lamina propria and muscularis mucosa of the large intestine. There was a significant decrease in the crypt depths without discernible change in the intestine permeability to any of the markers used. In addition, the iron-overloaded animals showed a significant number of iron-laden cells, which primarily consisted of macrophages, fibroblasts, myocytes, and adipocytes. In contrast, no iron-laden cells were present in tissues obtained from the normal control group. Thus, chronic experimental iron overload in rats leads to significant morphologic, but no permeability, alterations of the alimentary tract.