Microalgal Oil from Schizochytrium sp. Prevents HFD-Induced Abdominal Fat Accumulation in Mice

ABSTRACT

Objective: Dietary n-3 polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic acids (EPA) and docosahexaenoic acid (DHA), are proved to be effective in obesity reduction. Microalgal oil (MO) is an important alternative source of n-3 PUFAs that effectively alleviates obesity. The aim of the present study was to explore the anti-obesity effects of microalgal oil from Schizochytrium sp. (SMO) and to compare the effects of 2 SMOs (SMO1 and SMO2) with different levels of purity of n-3 PUFAs on high fat diet (HFD)-induced obesity in male C57BL/6J mice.

Methods: Mice were randomly divided into 5 groups: (1) regular chow (RC); (2) HFD; (3) HFD + fish oil (FO); (4) HFD + SMO1; and (5) HFD + SMO2. Body weight and food intake were weekly monitored. After 16 weeks of treatment, a glucose tolerance test (GTT) and an insulin tolerance test (ITT) were performed. Serum lipid profile, morphological changes in the liver and epididymal white adipose tissue (eWAT), and the mRNA expression of lipid metabolism–related genes were also examined.

Results: SMO treatment significantly decreased HFD-induced abdominal fat accumulation, lowered the levels of triglycerides, cholesterol, and low-density lipoprotein, as did the positive control treated with FO. Morphological examination revealed a remarkable reduction in lipid droplet formation in the liver tissue and the particle size of eWAT. An alleviation of inflammation infiltration in eWAT caused by a high-fat diet was also observed. Real-time reverse transcription–polymerase chain reaction analysis examination confirmed that microalgal oil inhibited the gene expression of fatty acid synthase, sterol responsive element-binding protein-1c, and acetyl-CoA carboxylase but promoted that of hormone-sensitive lipase and lipoprotein lipase, carnitine palmitoyltransferase-1, and uncoupling proteins in the liver and eWAT. Moreover, similar anti-obesity effects were obtained with the same dosage but different purity of n-3 PUFAs.

Conclusions: As an alternative n-3 PUFAs resource, dietary intake of SMO might be beneficial to prevent HFD-induced abdominal fat accumulation.

KEYWORDS:

• Anti-obesity
• docosahexaenoic acid
• eicosapentaenoic acid
• microalgal oil
• n-3 polyunsaturated fatty acids
• Schizochytrium sp.

Acknowledgments

The authors thank Dr. Li Zeng (University of Bristol), Dr. Chunxin Wang (National Institutes of Health), and Professor Xin Li (New York University) for help with experiment design, discussions, and expert language revision.

Funding

This study was supported by the Ministry of Science and Technology (No. 2012DFA30450, No. 2014DFA32120), the National Natural Science Foundation of China (No. 81471000), the National Natural Science Foundation of Liaoning (No. 2014023042), the Shandong Academy of Agriculture Sciences (No. 2015YQN32), and the Postdoctoral State Funding.