FATTY-ACID REGULATION OF FATTY-ACID-BINDING PROTEIN EXPRESSION IN THESMALL-INTESTINE

The effects of dietary oil intake and fatty acid infusions on the expr ession of intestinal and liver fatty acid-binding proteins (I-FABP and L-FABP, respectively) were investigated in the small intestine of mic e. A daily force-feeding for 7 days with 0.2 mi sunflower oil specific ally increased L-FABP mRNA and protein levels in duodenum and proximal jejunum. This upregulation was mediated in time- and dose-dependent m anners by a minute quantity of linoleic acid, the main fatty acid foun d in sunflower oil. The L-FABP induction was only found with long-chai n fatty acids, with the nonmetabolizable, substituted fatty acid alpha -bromopalmitate being far more active. A hormonally mediated effect is unlikely because long-chain fatty acids induced L-FABP mRNA in the Ca co-2 cell line cultured in serum-free medium. Therefore, long-chain fa tty acids are strong inducers of L-FABP gene expression in the small i ntestine. In contrast to data found in the rat, I-FABP gene expression appears to be unaffected by a lipid-enriched diet in the mouse.