Alanyl‐Glutamine‐Supplemented Parenteral Nutrition Increases Luminal Mucus Gel and Decreases Permeability in the Rat Small Intestine

Background: Effect of supplemental alanyl‐glutamine in standard TPN (S‐TPN) on luminal mucus gel and small intestinal permeability was investigated. Methods: Thirty Sprague‐Dawley rats were divided into group I (n = 10), receiving standard rat diet; group II (n = 10), receiving S‐TPN; and group III (n = 10), receiving alanyl‐glutamine‐supplemented TPN for 1 week. After 1 week, fluorescein isothiocyanate (FITC)‐dextran was injected into the small intestine of the rats, and they were killed. A small intestinal sample and portal blood were obtained for morphologic and functional analysis of mucus gel and intestinal permeability. Results: In group II, thickness and optical density of mucus gel per millimeter serosal length of intestine were significantly lower than group I (p <.001) and were significantly higher in group III than in group II ( p <.001). The number of goblet cells in the villi and in the crypt of the small intestine was significantly lower in group II than in group I (p <.001) and was significantly higher in group III than in group II (p <.001), with the exception of the villi of jejunum. Villous and crypt surface area per millimeter serosal length of intestine was significantly lower in group II than in group I (p <.001) and was significantly higher in group III than in group II (p <.001). Small intestinal permeability to FITC‐dextran was significantly higher in group II than in group I (p <.001) and was significantly lower in group III than in group II (p <.001). Glucosamine synthetase level was significantly higher in group III than in group I and ileum of group II (p <.001). Conclusions: Alanyl‐glutamine‐supplemented TPN prevents a decrease in mucus gel and an increase in small intestinal permeability associated with S‐TPN. (Journal of Parenteral and Enteral Nutrition 23: 24–31, 1999)