CHANGES IN FATTY-ACID COMPOSITION DURING CELL-DIFFERENTIATION IN THE SMALL-INTESTINE OF SUCKLING PIGLETS

Alterations of phospholipid fatty acid composition in the renewing intestine were studied in the infant piglet. Newborn piglets were fed from birth to 2 weeks of age a concentrated cow's milk which defined a standard supply of dietary fatty acids. Phospholipids were isolated from the whole mucosa, isolated intestinal cells and purified brush border membranes. Intestinal cells were isolated according to their position along the crypt-villus axis and cell phospholipids were extracted at each step of differentiation. Changes in fatty acid composition of cell phospholipids were related to those of lactase activity in the corresponding cell homogenates. In cell phospholipids, the relative content of linoleic and linolenic acids increased about 2-fold from crypt base to villus tip. Substantial contents of alkenylacyl glycerophospholipids (plasmalogens) were found in crypt cell phospholipids and in purified brush border membrane phosphatidylethanolamine (11 and 14% of alkenyl groups by weight of total fatty acids, respectively). The proportion of alkenylacyl glycerophospholipids decreased as cells ascended the villus column and became more differentiated. The results show that fatty acid compositional changes in differentiating cell phospholipids occurred in the immature intestine (before weaning) and suggest that these alterations might be related to the appearance of specific functions.