Fish Oil Suppresses Weight Gain and Fat Accumulation in the Liver on Weight Rebound in KK-A^y Mice

Abstract

We investigated the effect of fish oil on weight rebound in KK-A^y mice. We used two types of experimental diet: one containing beef tallow (diet B) and one containing fish oil (diet F). All the mice were fed diet B ad libitum to induce obesity, and then divided into four groups as follows: 1) B-B group: fed diet B with calorie restriction during the weight reduction period, then fed diet B ad libitum during the weight rebound period, and —using the same protocol— 2) B-F group, 3) F-B group, and 4) F-F group. In addition, a control group were fed diet B ad libitum during the entire experimental period. Final body weight was decreased in the B-F and F-F groups in comparison with the B-B and F-B groups. Compared with the control group, liver weight and the level of liver lipid were increased in the B-B and F-B groups and decreased in the B-F and F-F groups. In the B-F and F-F groups, SREBP-1c and FAS mRNA in the liver were decreased and PPAR-α and HSL mRNA in the liver were increased, in comparison with the B-B and F-B groups. The present findings suggest that fish oil suppresses body weight gain and fat accumulation in the liver on weight rebound in mice. Suppression of fat accumulation in the liver is attributed to inhibition of fatty acid synthesis, enhancement of lipolysis and fatty acid oxidation, and normalization of lipoprotein secretion from the liver.