Soybean oil induces neuroinflammatory response through brain-gut axis under high-fat diet

Neuroinflammation is considered the principal pathogenic mechanism underlying neurodegenerative diseases, and the incidence of brain disorders is closely linked to dietary fat consumption and intestinal health. To investigate this relationship, 60 8-week-old C57BL/6J mice were subjected to a 20-week dietary intervention, wherein they were fed lard and soybean oil, each at 15% and 35% fat energy. At a dietary fat energy level of 35%, inflammation was observed in both the soybean oil and lard groups. Nevertheless, inflammation was more pronounced in the mice that were administered soybean oil. The process by which nerve cell structure is compromised, inflammatory factors are upregulated, brain antioxidant capacity is diminished, and the TLR4/MyD88/NF-κB p65 inflammatory pathway is activated resulting in damage to the brain-gut barrier. This, in turn, leads to a reduction in the abundance of Akkermansia and unclassified_f_Lachnospiraceae, as well as an increase in Dubosiella abundance, ultimately resulting in brain inflammation and damage. These results suggested that soybean oil induces more severe neuroinflammation compared to lard. Our study demonstrated that, at a dietary fat energy level of 35%, compared to soybean oil, lard could be the healthier option, the outcomes would help provide a reference basis for the selection of residents' daily dietary oil.