Effect of intravenous and intragastric fat infusion on intestinal brush border enzyme activities in rats.

Intralipid was given to adult rats for 4 days either by intragastric or intravenous infusion. The villus height, protein content and the levels of sucrase, lactase and aminopeptidase activities were determined in the jejunum. The results were compared to values found in control rats fed orally with an equilibrated isocaloric diet. Intragastric or intravenous infusion of Intralipid caused a 50% reduction in the protein content of the brush border membrane, a significant drop of the specific (expressed per milligram protein) and segmental (expressed per centimeter intestinal length) activities of the disaccharidases, the maintenance of aminopeptidase activity and the lengthening of the villi in the jejunum. The major loss in disaccharidase activities was obtained when fat was given intravenously. Arguments favoring a hormone-mediated effect of the infused lipids on the intestinal function are presented and discussed.