Conjugated linoleic acids inhibit lipid deposition in subcutaneous adipose tissue and alter lipid profiles in serum of pigs.

Conjugated linoleic acids (CLAs) have served as a nutritional strategy to reduce fat deposition in adipose tissues of pigs. However, the effects of CLAs on lipid profiles in serum and how these lipid molecules regulate fat deposition are still unclear. In this study, we explored the effects of CLAs on regulating lipid deposition in adipose tissues in terms of lipid molecules and microbiota based on a Heigai pig model. A total of 56 Heigai finishing pigs (body weight: 85.58 ± 10.39 kg) were randomly divided into 2 treatments and fed diets containing 1% soyabean oil or 1% CLAs for 40 days. CLAs reduced fat deposition and affected fatty acids composition in adipose tissues of Heigai pigs via upregulating the expression of lipolytic gene (hormone sensitive lipase, HSL) in vivo and in vitro. CLAs also altered the biochemical immune indexes including reduced the content of total cholesterol (TChol), high-density lipoprotein (HDL-C), and low-density lipoprotein (LDL-C) and changed lipids profiles including decreased sphingolipids especially cermides (Cers) and sphingomyelins (SMs) in serum of Heigai pigs. Mechanically, CLAs may decrease peroxisome proliferator-activated receptorγexpression and further inhibit adipogenic differentiation in adipose tissues of pigs through suppressing the function of Cers in serum. Furthermore, Pearson's correlation analysis showed HSL expression was positively related to short chain fatty acids (SCFAs) in the gut (P < 0.05) but the abundance of Cers were negatively related to the production and functions of SCFAs (P < 0.05). CLAs altered the lipids distribution in serum and inhibited adipogenic differentiation through suppressing the function of Cers and further decreasing PPARγexpression in adipose tissues of Heigai pigs. Besides, the HSL expression and the abundance of Cers are associated with the production and functions of SCFAs in the gut.