Lipid composition of hepatocyte plasma membranes from geese overfed with corn |
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Authors: | J L Cazeils M Bouillier-Oudot A Auvergne M Candau R Babile |
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Affiliation: | Ecole Nationale Superieure Agronomique de Toulouse, Castanet-Tolosan, France. |
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Abstract: | Twelve-week-old Landes male geese were overfed with corn for 21 d in order to induce liver steatosis (fatty liver). Lipid
composition of hepatocyte plasma membranes from fatty livers was compared to that of lean livers obtained from geese fed a
normal diet. The ratio cholesterol/phospholipids was higher in fatty hepatocyte plasma membranes (0.63 vs. 0.47), whereas
the phospholipid/protein ratio was less than half. Overfeeding induced changes in fatty acid composition of hepatocyte plasma
membranes, including a greater than twofold increase in the percentage of oleic acid (29.7 vs. 13.8%) and a somewhat lesser
increase in lauric, palmitic, and palmitoleic acid contents of plasma membrane lipids of fatty livers. A concomitant reduction
in the proportion of stearic acid (18.4 vs. 25.1%) was also observed. In fatty livers, the increased ratio of saturated to
polyunsaturated fatty acids (PUFA) (1.5 vs. 1.0) was related to a significant decrease in PUFA content. Among all the PUFA,
only the eicosatrienoic acid (20∶3n−9) percentage was increased by liver steatosis. Overfeeding with corn appeared to induce
competition between de novo synthesized and dietary fatty acids incorporated in hepatocyte plasma membranes. This resulted in an accumulation of de novo synthesized monounsaturated and derived fatty acids in plasma membranes from overfed birds. A defect in the incorporation
of linoleic acid and linoleic- and linolenic-derived PUFA was observed despite the high proportion of these essential fatty
acids in the diet. It was conclued that in overfed palmipeds, de novo hepatic lipogenesis prevails over dietary lipid intake to modulate lipid composition of the fatty liver plasma membrane. |
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