Ileal lipid infusion stimulates jejunal synthesis of apolipoprotein A-IV without affecting mRNA levels

We examined the effect of ileal infusions of lipid emulsion on mRNA levels and biosynthesis of apolipoprotein A-IV (apo A-IV) in jejunal Thiry-Vella f istulas in rats. The rats were surgically prepared with jejunal Thiry-Vella fistulas; after recovery they were deprived of food, equipped with ileal i nfusion cannulas, then given 8 hr ileal infusions of fatty acid/monoglyceri de emulsions. Mucosal synthesis and transcript levels of apo A-IV in the Th iry-Vella loop were then measured. Lipid infusion produced a two-fold stimu lation in incorporation of H-3-leucine into apo A-IV-specific protein, but had no significant effect on apo A-IV mRNA levels. These results support th e hypothesis that a lipid-elicited, distal gut-derived, systemic signal sti mulates the production of apo A-IV by a post-transcriptional mechanism.