Liver fatty acid composition correlates with body fat and sex in a multigenic mouse model of obesity

To determine whether there is altered liver lipid-fraction fatty acid distribution in a multigenic obese mouse model, we examined livers from eight lean (0.2–4.2% carcass fat), seven intermediate (5.7–13.8%), and five obese (20.2–48.7%) backcross progeny [(C57BL/6J × Mus spretus) × C57BL/6J] aged 2–3 mo. Thirteen males and seven females were fed a nonpurified stock diet. Liver lipid fractions were separated and fatty acids quantitated by thin-layer and gas chromatography. There was a significant effect of obesity on 18:2ω6 in liver phospholipids (PL), cholesteryl esters, and triglycerides. PL 18:2ω6 was negatively correlated with carcass fat (r = −0.74, P < 0.001); 20:3ω6 was elevated in PL with increased obesity (P < 0.0001), and was correlated with carcass fat (r = 0.92, P < 0.0001); and 20:4ω6 in PL did not differ with obesity status. PL 20:3ω6 and 20:4ω6 were lower in males (P < 0.01 and 0.02, respectively) than in females. We conclude that obesity and sex affect distribution of ω6 essential fatty acids in mouse liver lipid fractions.