Abstract:

Conjugated linoleic acid (CLA), a mixture of positional and geometric isomers of linoleic acid with conjugated
double bonds, has attracted considerable attention since cis-9, trans-11-CLA (c9, t11-CLA) and trans-10, cis-12-CLA
(t10, c12-CLA) have a great application potential in medicines, foods and health products based on anticancer, immune
regulatory, anti-atherosclerosis, anti-obesity and antioxidant activities. In this study, Kunming mice were used as
experimental subjects to evaluate the inhibitory effect of CLA (80% purity, containing 36.40% c9, t11-CLA, 36.26%
t10, c12-CLA and 7.14% other CLA isomers) on the obesity of mice. The tested mice were divided into obesity model
control group, normal control group and CLA treatment group, and the mice in the CLA treatment group were administered
with CLA by gavage for six weeks, and then obesity indexes, such as body weight, Lee’s index, total weight of fat, fatty
coefficient, and total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C), high density
lipoprotein cholesterol (HDL-C) in serum, fatty acid synthase (FAS) in liver and viscera of the mice, were measured. The
results showed that the obesity indexes, including Lee’s index, fatty coefficient, TC, TG and LDL-C, in the CLA treatment
groups at various dosages were significantly lower than the obesity model control group (P < 0.05 or P < 0.01), and HDL-C
was significantly higher than the obesity model control group (P < 0.01). Lee’s index, fatty coefficient, TC, TG, and LDL-C
decreased with increasing CLA dose, while HDL-C increased. High-dose CLA (0.15 mL/10 g) could control the obesity
indexes of obesity model control group to the level of the normal control group, and CLA treatment at each dose had no
significant effect on the viscera of the mice; therefore, CLA could inhibit obesity and had no toxic side effect on the growth
of mice. The Lee’s index, fatty coefficient, TC, TG, and LDL-C had high positive correlation with FAS, while HDL-C
had a highly negative correlation. An obvious correlation between FAS and obesity index was observed and it was further
confirmed that FAS is the potential target of obesity. CLA treatment can significantly reduce FAS (P < 0.01), and this could
be the mechanism of its antiobesity effect.

Key words: conjugated linoleic acid (CLA), obesity inhibition, fatty acid synthase (FAS)