Hepatic lipid accumulation is ameliorated in obese KK mice by dietary sei whale oil
Whale oil (WO) contains n-3 polyunsaturated fatty acids (PUFAs), but the effects of whale oil intake on lipid metabolism have remained unclear. We examined the influence of WO on lipid metabolism in obese KK mice. Male KK mice were fed a high-fat diet for 12 weeks to induce obesity. The mice were then given free access to a different diet for 10 weeks: the lard/safflower oil (LSO) diet consisted of 25 energy% (en%) LSO (6:4), the WO diet consisted of 25 en% WO, and the fish oil (FO) diet consisted of 11 en% FO plus 14 en% LSO. The n-3 PUFA content of the FO diet was the same as that in the WO diet. In the WO and FO groups, the total plasma cholesterol level was significantly decreased compared with that in the LSO group. The number of lipid droplets in liver specimens was also lower in the WO and FO groups, and the hepatic triglyceride and total cholesterol levels were decreased in these groups compared with the LSO group. Hepatic mRNA levels of fatty acid synthase, and stearoyl-CoA desaturase 1, which are fatty acid synthesis-related genes, were decreased in the WO and FO groups. No significant differences were observed between the WO and FO groups. Taken together, these results indicate that WO intake inhibits lipid accumulation in the liver by reducing fatty acid biosynthesis.
KeywordsWhale oil n-3 PUFA Lipid metabolism Hepatic lipids
Cholesterol 7 α-hydroxylase
Diacron of reactive oxygen metabolites
Enzyme-linked immunosorbent assay
Fatty acid synthase
Medium-chain acyl-CoA dehydrogenase
Nonalcoholic fatty liver disease
Non-esterified fatty acid
Polymerase chain reaction
Peroxisome proliferator-activated receptor
Polyunsaturated fatty acid
Sterol regulatory element-binding protein
White adipose tissue
We would like to thank NOF Corporation (Tokyo, Japan) for providing FO. This study was supported in part by Grant-in-Aid for Scientific Research on Innovative Areas (to S.S., Grant No. 22126004) and Grant-in-Aid for Young Scientists (B) (to S.H., Grant No. 90644261) from the Ministry of Education, Culture, Sports, Science and Technology of Japan.
Compliance with ethical standards
Conflict of interest
This study was funded by Kyodo Senpaku Kaisha, Ltd, Tokyo, Japan.
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