Involvement of (n-6) essential fatty acids and prostaglandins in liver lipid accumulation in Japanese quail

Objective - To investigate the involvement of (n-6) essential fatty acids, such as linoleic acid [18:2(n-6)] or γ-linolenic acid [18:3(n-6)], and of prostaglandins on liver lipid accumulation in Japanese quail. Design - Effects of graded amounts of aspirin, which inhibits prostaglandin synthesis, on liver weight were determined in experiment 1. Experiment 2 was designed to clarify the effect of dietary essential fatty acid sources and inhibition of prostaglandin synthesis on the liver fat and fatty acid profile. Animals - Female Japanese quail. Procedure - In experiment 1, from 1 to 3 weeks of age, birds were fed ad libitum the essential fatty acids-free or linoleic acid-adequate (2%) diets with graded amounts of aspirin (0, 0.1, 0.2, and 0.4%). In experiment 2, from 1 to 4 weeks of age, birds were fed the same amount of essential fatty acids-free, linoleic acid-adequate, or γ-linolenic acid (0.4%) diets with (0.2%) or without aspirin. Results - In experiment 1, in groups given the essential fatty acids-free diet, liver weight increased with an increase in dietary aspirin concentration. In experiment 2, γ-linolenic acid completely prevented liver triacylglycerol and cholesterol accumulation induced by the essential fatty acids-free diet. Aspirin treatment significantly lowered plasma prostaglandin F(2α) concentration, but did not affect liver lipid concentrations. In groups fed the essential fatty acids-free diets, however, aspirin treatment increased liver weight and liver triacylglycerol concentration by 20 and 40%, respectively. Conclusions - γ-Linolenic acid or its metabolites, but not linoleic acid itself, are important factors in reducing fatty liver in Japanese quail with the essential fatty acids deficient condition.