L-GLUTAMINE AND TRANSFORMING GROWTH-FACTOR-ALPHA ENHANCE RECOVERY OF MONOACYLGLYCEROL ACYLTRANSFERASE AND DIACYLGLYCEROL ACYLTRANSFERASE ACTIVITY IN PORCINE POSTISCHEMIC ILEUM

Recovery of the ability to digest and absorb lipids is essential to th e maintenance of normal nutrition in infants with bowel damage. Two in trinsic microsomal enzymes, monoacylglycerol acyltransferase (MOAT) an d diacylglycerol acyltransferase (DGAT), catalyze the major pathway fo r intestinal triacylglycerol biosynthesis. This study describes the ef fects of intestinal ischemia on epithelial DGAT and MGAT activities an d their recovery in response to two luminal treatments: L-glutamine (G in), the primary intestinal fuel, and transforming growth factor-ct (T GF-cr), a mitogenic hormone similar to epidermal growth factor present in breast milk. Ischemic damage and recovery were analyzed in mucosa from Thiry-Vella loops in the mid-ileum of 7-wk-old pigs. Loops were s ubjected to 2-h occlusion of local mesenteric arteries, followed by 6 or 72 h of recovery in the presence of luminal glucose (control), Gin, or TGF-alpha. Ischemic tissue followed by 6-h recovery exhibited an a pproximate 50% decrease in both MOAT and DGAT activities compared with nonischemic loop tissue, At 72 h, MGAT and DGAT recovery in Gin plus TGF-alpha-treated loops was significantly greater than their correspon ding 6-h peak damage levels (p < 0.05). From 6 to 72 h, MGAT increased 4-fold and DGAT increased 3.6-fold after Gin plus TGF-alpha treatment , With other treatments, MGAT and DGAT activities increased <2.5-fold from 6 to 72 h. This study shows that intestinal MGAT and DGAT activit ies decrease after ischemic damage, yet recover rapidly in bowel expos ed to Gin and/or TGF-alpha, By stimulating the rate of recovery of the villi and lipid synthesizing enzymes, these treatments could improve the efficacy of enteral feeding in infants recovering from bowel damag e.