The 10trans, 12cis isomer of conjugated linoleic acid promotes energy metabolism in OLETF rats

We investigated the effect of conjugated linoleic acid (CLA) on energy metabolism in Otsuka Long-Evans Tokushima Fatty (OLETF) rats. In experiment 1, male OLETF rats were fed either control diet, 10% safflower oil or CLA diet, 9% safflower oil plus 1% CLA for 4 wk. In experiment 2, male OLETF rats were fed either 9c,11t-CLA diet, 9% safflower oil plus 1% 9c,11t-CLA–rich oil or 10t,12c-CLA diet, 9% safflower oil plus 1% 10t,12c-CLA–rich oil for 10 d. In experiment 1, after 4 wk of feeding, serum and hepatic triacylglycerol concentrations in the CLA group were decreased significantly as compared with the control group. The CLA diet increased oxygen consumption and energy expenditure as compared with the control diet in OLETF rats. In experiment 2, a significant reduction of serum and hepatic triacylglycerol concentrations was seen in the 10t,12c-CLA group as opposed to the 9c,11t-CLA group. Oxygen consumption and energy expenditure were significantly higher in the 10t,12c-CLA group than in the 9c,11t-CLA group. These results demonstrated that the hypolipidemic effect and the enhancement of energy metabolism by CLA can be attributed to the effect of the 10t,12c-CLA isomer.