Diet Fat and Oral Insulin‐Like Growth Factor Influence the Membrane Fatty Acid Composition of Suckling Rat Small Intestine

Abstract

Background:Insulin‐like growth factor‐1 plays an important role in small intestine development. The presence of insulin‐like growth factor‐1 and the complexity of the fatty acid composition in breast milk suggests that intestinal development may be influenced by manipulating the levels of these components.Methods:To determine whether a physiological dose of insulin‐like growth factor‐1 would influence sucrase and lactase activity levels, 10‐day‐old suckling rat pups were treated with an oral gavage of insulin‐like growth factor‐1. Four diets differing in fat composition were fed to lactating dams. Brush border membranes were isolated from jejunal and ileal segments of suckling rat small intestine. Fatty acid analysis of choline and ethanolamine phospholipids was performed.Results:Insulin‐like growth factor‐1 was found to have no effect on the sucrase and lactase activities of suckling rats. Changes in the diet fat composition of the mother's diet indirectly influenced the fatty acid composition of suckling rat small intestine. Insulin‐like growth factor‐1 decreased ileal C20:4n‐6 levels. A correlation was observed between lactase activity and C20:4n‐6 and C22:6n‐3 levels. As C20:4n‐6 levels increased, lactase activity appeared to decline. Increased lactase activity was observed when C22:6n‐3 levels increased.Conclusions:The changes observed in C20:4n‐6 levels in response to oral insulin‐like growth factor‐1, combined with the apparent trend of increased lactase activity with declining levels of C20:4n‐6, may be of significance in the development of the small intestine in early life.