Effets de l’acide trans-10, cis-12 linoléique sur le métabolisme des lipides dans le foie chez la souris C57BL/6

A 4-week diet containing 1% of the conjugated trans-10,cis-12 linoleic acid (CLA2) induces, in C57BL/6 mice, a lipodystrophy, a liver steatosis and a reduction of plasma triglycerides. We demonstrate that, first, hepatic lipid accumulation is not due to an in vivo alteration of lipoprotein production. Fates of CLA2 relative to ß-oxidation reactions are then studied in mitochondrial fractions isolated from liver of control animals and the data indicate not only that the CLA is poorly oxidised but also that it modifies the oxidation of usual fatty acids. We also demonstrate that oxidation capacities are increased by CLA2 treatment concomitantly to carnitine palmitoyltransferase I (CPT I) activity. Besides, the increases in acetyl-CoA carboxylase activity and malonyl-CoA concentration in the liver of CLA2 treated mice provide evidence of a high rate of lipogenesis. The increased CPT I sensibility to malonyl-CoA inhibition due to the treatment suggests that the whole fatty acid ß-oxidation is finally reduced in vivo. The mechanisms implicated in the setup of the hepatic steatosis and in the reduction of the lipaemia despite the increased VLDL secretion are discussed