Changes within Liver Accounts for Fatty Acids Decrease in the Blood of Rats with Adjuvant‐Induced Arthritis

Abstract This study characterizes rheumatoid arthritis‐related free fatty acids (FFAs) changes using adjuvant‐induced arthritis (AIA) model. Blood FFAs of healthy and AIA rats are periodically determined. During acute inflammation, FFAs levels are analyzed under both fasting and non‐fasting conditions. Oral intake capacities are compared by everted intestinal sac experiment. Tissue distribution of FFAs in the rats fed with/without linolenic acid is also investigated. AIA decreases FFAs in rats. Saturated FFAs are gradually recovered, but unsaturated FFAs are further reduced till the secondary inflammation. FFAs level gap remains unchanged regardless of feeding/fasting, and intestinal intake capacities of the rats are similar. FFAs levels in liver fluctuate in accordance with blood levels. Increased carnitine palmitoyltransferase 1 (CPT‐1) reveals the accelerated FFAs utilization in AIA rats, resulting in the accumulation of acetoacetic acid and 2‐hydroxybutyrate. Hepatocytes incubated with AIA serum take in more FFAs than normal controls when supply is sufficient. To the opposite, intracellular FFAs are reduced after AIA serum stimulus without additional supply. Besides, AIA serum‐challenged cells produce more CPT‐1. Hence, the reduced circulating FFAs in AIA rats should be attributed to the accelerated utilization in liver. Practical Applications : This study provides additional possible therapeutic approaches for the treatment of RA by focusing on the changes of blood FFAs. Obtained clues demonstrate that liver will be a key in the elucidation of RA‐related lipid paradox, and diet supplement of the unsaturated FFAs will be beneficial in treating RA.