Dietary lipid sensing through fatty acid oxidation and chylomicron formation in the gastrointestinal tract of rainbow trout

• Published in: Comparative biochemistry and physiology. Part A, Molecular & integrative physiology Vol. 294; p. 111638
• Main Authors: Calo, Jessica, Blanco, Ayelén M., Soengas, José L.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.08.2024
• Subjects: Animals; Carnitine O-Palmitoyltransferase - genetics; Carnitine O-Palmitoyltransferase - metabolism; Chylomicron; Chylomicrons - metabolism; Dietary Fats - metabolism; Dietary Fats - pharmacology; Epoxy Compounds - metabolism; Epoxy Compounds - pharmacology; Fatty acid oxidation; Fatty Acids - metabolism; Feed intake; Fish; Gastrointestinal Tract - metabolism; Gut sensing; Lipid Metabolism; Oncorhynchus mykiss - metabolism; Oxidation-Reduction; Fatty acid oxidation; Gut sensing; Fish; Chylomicron; Feed intake
• ISSN: 1095-6433; 1531-4332
• DOI: 10.1016/j.cbpa.2024.111638

In mammals, physiological processes related to lipid metabolism, such as chylomicron synthesis or fatty acid oxidation (FAO), modulate eating, highlighting the importance of energostatic mechanisms in feeding control. This study, using rainbow trout (Oncorhynchus mykiss) as model, aimed to characterize the role of FAO and chylomicron formation as peripheral lipid sensors potentially able to modulate feeding in fish. Fish fed with either a normal- (24%) or high- (32%) fat diet were intraperitoneally injected with water alone or containing etomoxir (inhibitor of FAO rate-limiting enzyme carnitine palmitoyl-transferase 1). First, feed intake levels were recorded. We observed an etomoxir-derived decrease in feeding at short times, but a significant increase at 48 h after treatment in fish fed normal-fat diet. Then, we evaluated putative etomoxir effects on the mRNA abundance of genes related to lipid metabolism, chylomicron synthesis and appetite-regulating peptides. Etomoxir treatment upregulated mRNA levels of genes related to chylomicron assembly in proximal intestine, while opposite effects occurred in distal intestine, indicating a clear regionalization in response. Etomoxir also modulated gastrointestinal hormone mRNAs in proximal intestine, upregulating ghrl in fish fed normal-fat diet and pyy and gcg in fish fed high-fat diet. These results provide evidence for an energostatic control of feeding related to FAO and chylomicron formation at the peripheral level in fish. [Display omitted] •High-fat diet did not produce changes in feed intake in rainbow trout.•Generally, etomoxir did inhibit Cpt1 activity in fish and modified feed intake.•The results highlight the existence of an energostatic control of eating in fish.•Fat affects differentially to chylomicron assembly depending on intestinal region.