Effect of daily ethanol ingestion on intestinal permeability to macromolecules.

The effects of regular ethyl alcohol ingestion on morphological and permeability characteristics of the small intestine were assessed in mature rats using the tracer protein, horseradish peroxidase. Thirty adult rats were divided into two groups and provided a standard commercial diet in pellet form. Each morning, after an overnight fast, every animal in the experimental group was administered by gavage an aliquot of 20% ethanol; animals in the control group were provided aliquots of 20% sucrose in water by the same method. After 4 and 8 weeks on the gavage routine (and 10 days and 4 weeks after gavage cessation), jejunal permeability to horseradish peroxidase was examined in animals from each group. Using a routine ligated-loop procedure and light and electron microscopy, ethanol-exposed rats demonstrated increased intestinal permeability to horseradish peroxidase by 4 weeks; sucrose-exposed animals revealed little alteration in mucosal integrity. It is proposed that regular ingestion of sizable amounts of alcohol alters morphological characteristics of the gut and increase the permeability of the mucosa to "undigested" macromolecules.