Genes involved in the establishment of hepatic steatosis in Muscovy, Pekin and mule ducks
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Our main objectives were to determine the genes involved in the establishment of hepatic steatosis in three genotypes of palmipeds. To respond to this question, we have compared Muscovy ducks, Pekin ducks and their crossbreed the mule duck fed ad libitum or overfed. We have shown a hepatic overexpression of fatty acid synthase (FAS) and di-acyl glycerol acyl transferase 2 (DGAT2) in overfed individuals, where DGAT2 seemed to be more regulated. This increase in lipogenesis genes is associated with a decrease of lipoprotein formation in Muscovy and mule ducks, especially apolipoprotein B (ApoB) and Microsomal Triglyceride Transfer Protein (MTTP), leading to lipid accumulation in liver. In Pekin ducks, MTTP expression is upregulated suggesting a better hepatic lipids exportation. Regarding lipids re-uptake, fatty acid-binding protein 4 and very-low-density-lipoprotein receptor are overexpressed in liver of mule ducks at the end of the overfeeding period. This phenomenon puts light on a mechanism unknown until today. In fact, mule can incorporate more lipids in liver than the two other genotypes leading to an intensified hepatic steatosis. To conclude, our results confirmed the genotype variability to overfeeding. Furthermore, similar observations are already described in non-alcoholic fatty liver disease in human, and ask if ducks could be an animal model to study hepatic triglyceride accumulation.
KeywordsHepatic steatosis Lipids Gene expression Ducks NAFLD
We thank the “Conseil Général des Landes” and the “Comité Interprofessionnel des Palmipèdes à Foie Gras” (CIFOG) for financing this work. We also thank the technical staff of INRA Artiguères for rearing ducks (Certificate of Authorization to Experiment on Living animals, No. B40-037-1, Ministry of Agriculture and Fish Products, ethic committee Aquitaine birds and fish no.C2EA-73). We are grateful to Hélène Manse and team of GenPhySE for their excellent technical assistance in Folch analysis (INRA UMR 1388 Génétique, Physiologie et Systèmes d’Elevage (GenPhySE), F-31326 Castanet-Tolosan, France). We would also like to thank Frédéric Martins and Jean-José Maoret for performing Fluidigm analysis [Génopole Toulouse/Midi-pyrénées, Plateau Transcriptomique Quantitative (TQ), Toulouse, France].
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