Su1777 GIP Activation of Signaling Pathways Traffick PepT1 Proteins to the Apical Membrane of Intestinal Epithelial Cells

Abstract

Background: In our previous study, using lymph fistula rat model, we have shown that fat ingestion stimulates release of mast cell mediators such as histamine, rat mucosal mast cell protease II (RMCP II), and prostaglandin D2 (PGD2) into intestinal lymph; however, it is unclear whether these responses are different depending on the type of fatty acid ingested. Aim: The purpose of this study was to determine the effects of dietary long-chain fatty acids with varying degrees of saturation on intestinal mast cell activation. Methods: We investigated lymphatic mast cell mediator concentrations after administration of three types of triacylglycerols, trilinolein (C18:2 n-6), trilinolenin (C18:3 n-3) or triolein (C18:1 n-9) by using the lymph fistula rat model. After cannulation of the major mesenteric lymph duct and duodenum of male Sprague-Dawley rat, a 3 ml bolus mixture of phosphate-buffered, taurocholatestabilized emulsion containing 120μmol of trilinolein or trilinolenin or triolein was provided to each animal through the intraduodenal feeding tube. The emulsion medium without triacylglycerol was used as control. Lymph was continuously collected for 6 hours and analyzed for RMCPII, histamine, PGD2, triglyceride and protein content. Results: Infusion of trilinolein and trilinolenin significantly increased the lymphatic release of mast cell mediators and influenced lymphatic protein concentration. In contrast, triolein did not induce the release of mast cell mediators. The peak RMCPII concentration after infusion of trilinolein (432.97 ± 77.53 ng/ml) and trilinolenin (317.50 ± 47.59 ng/ml) were significantly greater than triolein (141.46 ± 23.46 ng/ml) ( P,0.01, P,0.05, respectively). Similar to the RMCPII response, the peak values of histamine were significantly greater than triolein (12.97 ± 0.62ng/ml) for trilinolein (34.2 ± 1.7 ng/ml, P,0.01, n=3) and trilinolenin (19.85 ± 1.06ng/ ml, P,0.01, n=3). Infusion of trilinolein induced a significant increase of lymphatic PGD2 concentration peaked at 2 hour compared with the control (1461.23 ± 133.12 vs. 842.30 ± 129.02 pg/ml, P,0.05), but triolein did not induce (978.43 ± 153.74 pg/ml). Conclusion: These observations identify that the intestinal mast cell activation induced by dietary fat is dependent on the degree of unsaturation in fatty acid.