Tardy AL, Giraudet C, Rousset P, Rigaudière JP, Laillet B, Chalancon S, Salles J, Loreau O, Chardigny JM, Morio B - 35200 N - J Lipid Res 2008 ; en cours de publication : 38p.

Effects of diets enriched in trans monounsaturated fatty acids of natural and industrial source on muscle mitochondrial function and insulin sensitivity in rats

Epidemiological studies suggest that chronic consumption of trans MUFA may alter muscle insulin sensitivity. The major sources of dietary trans MUFA (dairy fat vs. industrially hydrogenated oils) have different isomeric profiles and thus probably different metabolic consequences. These effects may involve alterations in muscle mitochondrial oxidative capacity, which may in turn promote insulin resistance if fatty acid oxidation is reduced. We report that in Wistar rats, an 8-week diet enriched (4% of energy intake) in either dairy, industrial or control MUFA did not alter insulin and glucose responses to an intraperitoneal glucose tolerance test (1g/kg). In C2C12 myotubes, vaccenic and elaidic acids did not modify insulin sensitivity compared with oleic acid. Furthermore, the ex vivo total, mitochondrial and peroxisomal oxidation rates of [1-14C]-oleic, vaccenic and elaidic acids were similar in soleus and tibialis anterior rat muscle. Finally, an 8-week diet enriched in either dairy or industrial trans MUFA did not alter mitochondrial oxidative capacity in these two muscles compared with control MUFA but did induce a specific reduction in soleus mitochondrial ATP and superoxide anion production (p<0.01 vs. control). In conclusion, dietary trans MUFA of dairy and industrial origin have similar effects and do not impair muscle mitochondrial capacity and insulin sensitivity.