Serum Levels of Free Fatty Acids in Obese Mice and Their Associations with Routine Lipid Profiles

Abstract

Purpose

To investigate serum levels of free fatty acids (FFAs) and their associations with routine serum lipids in diet-induced obese mice, which have been scantily reported before.

Methods

Male C57BL/6 J mice were fed high-fat diets for 12 weeks to induce obesity. Levels of serum FFAs were measured by ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry.

Results

Obese mice had higher serum levels of total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C), but lower triglycerides (TG) than control mice. A total of 30 FFAs were found, and 3 saturated fatty acids (SFAs), all 8 monounsaturated fatty acids (MUFAs) and 7 polyunsaturated fatty acids (PUFAs) decreased in obese mice, but one SFA (C4:0) increased. Differences in the relative levels of individual FFAs to total FFAs, SFAs, MUFAs or PUFAs between obese and control mice were different from each other and from those evaluated by concrete levels except C4:0, C16:1, C19:1 and C18:4. Only the concrete levels of C4:0, C22:3 and C18:4 were associated with routine serum lipids, including C22:3 negatively with TG in control mice, and C4:0 and C18:4 positively with LDL-C in obese mice, although the relative levels of C4:0 to total MUFAs negatively with TC, and C23:3 to total SFAs or MUFAs negatively with TG in control mice. Different relative levels of the remaining FFAs were differently associated with different routine serum lipids in obese and/or control mice.

Conclusion

Obesity may influence serum FFAs profiles. The relationship of individual FFAs and their relative levels to other FFAs with routine serum lipids in obese and control mice suggests that individual FFAs may interact with others and obesity on levels of routine serum lipids. Once confirmed, the interactions may be novel perspectives when fatty acids are used to improve hyperlipidemia in the subjects with obesity.

Keywords:

• free fatty acid
• obesity
• triglyceride
• cholesterol
• high-density lipoprotein
• low-density lipoprotein

Abbreviations

BMI, higher body mass index; CVD, Cardiovascular disease; DHA, docosahexaenoic acid; DNL, de novo lipogenesis; D6D, δ-6 desaturase; EPA, eicosapentaenoic acid; FFAs, free fatty acids; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; MUFAs, monounsaturated fatty acids; PUFAs, polyunsaturated fatty acids; SCD1, stearoyl-CoA desaturase 1; SFAs, saturated fatty acids; TC, total cholesterol; TG, triglycerides; USFAs, unsaturated fatty acids.

Ethical Approval

This study was approved by the Medical Ethics Committee of Sichuan University.

Consent for Publication

All authors approved the paper publication.

Acknowledgments

The present study was supported by the National Natural Science Foundation of China (grant no. 81974043). Professor Ding Zhi Fang is the recipient of the grant.

Disclosure

The authors declare no conflicts of interest in this work.