MEDIUM-CHAIN COMPARED WITH LONG-CHAIN TRIACYLGLYCEROL EMULSIONS ENHANCE MACROPHAGE RESPONSE AND INCREASE MUCOSAL MASS IN PARENTERALLY FED RATS

We tested whether infusion of medium-chain triacylglycerols (MCTs) dur ing total parenteral nutrition (TPN) enhanced macrophage response and reduced intestinal atrophy compared with long-chain triacylglycerols ( LCTs). Male Sprague-Dawley rats (230-240 g) were maintained with TPN p roviding 16% or 48% of nonprotein energy from MCTs plus LCTs or LCTs a lone or 100% of nonprotein energy from dextrose for 6 or 12 d. Body we ight gain was not significantly different among groups. Serum concentr ations of beta-hydroxybutyrate were greater with MCTs plus LCTs than w ith LCTs alone after 6 d (P < 0.05, main effect). Triacylglycerol conc entrations in liver were greater with LCTs than with MCTs plus LCTs af ter 6 or 12 d (P < 0.05, main effect). MCTs plus LCTs increased by 50% the percentage (P < 0.0005) and number of splenic macrophages compare d with LCTs alone in conjunction with decreased triacylglycerol concen trations in spleen after 6 d (P < 0.05, main effect). In vitro tumor n ecrosis factor alpha secretion by splenic or circulating macrophages i n response to lipopolysaccharide was increased by MCTs plus LCTs compa red with LCTs alone, twofold after 6 and sevenfold after 12 d (P < 0.0 5, main effect). Jejunal mucosal mass was 30% greater with MCTs plus L CTs than with LCTs alone after 6 or 12 d (P < 0.01); villus height was also significantly greater after 6 d (main effect). The incidence of bacterial translocation to the mesenteric lymph nodes was not signific antly different among groups. Compared with LCTs, MCTs enhanced macrop hage response and decreased intestinal atrophy.