Submitted on March 3, 2008
Revised on March 31, 2008
Accepted on April 17, 2008
Metabolism of Apical vs. basolateral sn-2-monoacylglycerol and fatty acids in rodent small intestine
Judith Storch, Yin Xiu Zhou, and William S. Lagakos
Nutritional Sciences, Rutgers University, New Brunswick, NJ 08901
Corresponding Author: storch{at}aesop.rutgers.edu
The metabolic fates of radiolabeled sn-2-monoolein (MG) and oleate (FA) in rat and mouse intestine, added in vivo to the apical (AP) surface in bile salt micelles, or to the basolateral (BL) surface via albumin-bound solution, were examined. Mucosal lipid products were quantified, and the results demonstrate a dramatic difference in the esterification patterns for both MG and FA, depending upon their site of entry into the enterocyte. For both lipids, the ratio of triacylglycerol to phospholipid (TG:PL) formed was approximately 10-fold higher for delivery at the AP relative to the BL surface. Further, a 3-fold higher level of FA oxidation was found for BL compared to AP substrate delivery. Incorporation of FA into individual PL species was also significantly different, with > 2-fold greater incorporation into phosphatidylethanolamine and a 3-fold decrease in the phosphatidylcholine: phosphatidylethanolamine ratio for AP- compared to BL- added lipid. Overnight fasting increased the TG:PL incorporation ratio for both AP and BL lipid addition, suggesting that metabolic compartmentation is a physiologically regulated phenomenon. These results support the existence of separate pools of TG and glycerolipid intermediates in the intestinal epithelial cell, and underscore the importance of substrate trafficking in the regulation of enterocyte lipid metabolism.
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