Fish Oil Present in High-Fat Diet, Unlike Other Fats, Attenuates Oxidative Stress and Activates Autophagy in Murine...

Background/Objectives: Increased fat intake and high content of saturated fatty acids in the diet are associated with higher body weight and an increased risk of obesity. This study aimed to determine the impact of a high-fat diet (HFD) on white adipose tissue (WAT) metabolism and to verify whether this effect depends on the sources of lipids in HFD. Methods: Male C57BL/6J mice, 7 weeks old, received a control (Ctrl.) or high-fat diet (HFD) with 10% and 45% energy from fat, respectively, for 15 weeks. Lard was used as the main dietary fat in the HFD group. Next, the HFD group was subdivided into HFD-L, HFD-CO, HFD-OO and HFD-FO groups differing in the lipid sources (lard, coconut oil, olive oil, fish oil, respectively). The experiment was continued for 12 consecutive weeks. The study analyzed the concentration of different fatty acids in visceral (VAT) and subcutaneous (ScAT) adipose tissue; the levels of autophagy markers: beclin1, Atg5, LC3, p62, AMPK; ER stress markers: phos-PERK, CHOP, XBP-1 and oxidative stress parameters: TAS and TBARS in VAT and ScAT. Results: Mice in all HFD groups showed increased body mass and adipose tissue hypertrophy. Blood glucose concentration remained elevated in the HFD-L group but normalized in other HFD groups by the end of the dietary intervention. Fatty acid content in VAT and ScAT reflected the dietary sources in HFD. The HFD-L, HFD-CO, HFD-OO groups showed increased beclin1, ATG5, and p62 levels in VAT but the LC3-II/LC3-I ratio was similar to the control, suggesting impaired autophagic flux. In the HFD-FO group, the LC-II/LC-I ratio was elevated, along with decreased p62 levels, indicating active autophagic degradation. Changes in autophagy activity were insignificant in ScAT. ER stress markers were also mostly unaffected by HFD in both adipose tissue depots. TAS and TBARS values in VAT and ScAT were similar in the HFD-L and HFD-CO groups, and the HFD-OO group showed increased TAS and decreased TBARS, while the HFD-FO reduced TBARS. Conclusions: Antioxidant capacity and autophagy activity in WAT depended on fat content and lipid source, especially in the visceral depot. Fish oil induced changes in cellular metabolism, especially in VAT, diminishing the detrimental effects of HFD.