EPA but not DHA prevents lipid metabolism disorders by regulating myogenic IL-6 in high-fat fed mice.

Lipid metabolism disorder serve as a critical starting point for the development of chronic non-communicable diseases (NCDs). Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA) are known for their lipid-lowering properties, but few studies have revealed their differences from the perspective of skeletal muscle endocrinology. Myogenic IL-6 has garnered significant attention for its role in energy distribution. The primary aim of this study was to investigate the effects and mechanisms of EPA and DHA on myogenic IL-6 and lipid metabolism disorders in mice, and to clarify the association between the alleviation of lipid metabolism disorders and myogenic IL-6 mediated by EPA/DHA. We found that EPA and DHA not only prevented high-fat diet-induced lipid metabolism disorders, but also up-regulated the expression of myogenic IL-6 by activating TRPV1/Ca signaling in skeletal muscle. However, the lipid metabolism prevention effect mediated by EPA was weakened after knockout gene of myogenic IL-6, with its body weight and body fat increased and a large amounts of lipid deposited in the blood, liver, and adipocytes. Meanwhile, there no significantly differences of AMPK/STAT3 signaling in adipose tissue between groups after knockout gene of myogenic IL-6. Based on the results above, we concluded that EPA and DHA can stimulate the production of myogenic IL-6 through TRPV1/Ca signaling in skeletal muscle. The prevention effect of lipid metabolism disorders by EPA, but not DHA, relies on myogenic IL-6, with the underlying mechanism may involving the enhancement of AMPK/STAT3 signaling mediated by myogenic IL-6 in adipose tissues.