N-3 polyunsaturated fatty acids ameliorate hepatic steatosis via the PPAR-α/CPT-1α pathway in a mouse model of parenteral nutrition.

Parenteral nutrition (PN) is one of the basic therapies for patients with intestinal failure; however, hepatic steatosis associated with PN limits the long-term use of PN. N-3 polyunsaturated fatty acids (PUFAs) have been used to improve clinical outcomes of patients receiving PN; however, the mechanisms by which n-3 PUFAs ameliorate hepatic steatosis remain unclear. In the present study, C57BL/6J mice were randomly assigned to three treatment groups, namely, enteral nutrition (EN), n-3 PUFAs, and n-6 PUFAs. Additionally, MK 886 was used to inhibit PPAR-α. After 7 days of intervention, mice were sacrificed, and liver tissue and serum samples were collected. Results from liver weight and liver triglyceride measurements and Oil Red O staining showed that n-3 PUFAs significantly reduced the liver triglyceride levels. In addition, treatment with n-3 PUFAs resulted in a greater decrease in serum triglyceride and low-density lipoprotein cholesterol levels compared to n-6 PUFAs. The key enzymes involved in FA oxidation, namely, PPAR-α and CPT-1α, were significantly restored at both the mRNA and protein levels in the n-3 PUFAs group. However, the benefits of n-3 PUFAs in improving serum and liver TG levels were abolished when the PPAR-α/CPT-1α pathway was blocked by MK 886. The results of this study indicated that n-3 PUFAs ameliorated the PN-associated hepatic steatosis by activating the PPAR-α/CPT-1α pathway. The present study provided a reliable scientific basis supporting the potential beneficial effects of n-3 PUFAs for improving hepatic steatosis in patients receiving long-term parenteral nutrition.