Background: In human beings, women are at lower risk of cardiovascular diseases, and respond differently from men to dietary fatty acids.
Aim: The aim of the present study was to investigate (i) the influence of gender on the response of lipid metabolism to dietary n-3 PUFA, and (ii) the contribution of PPARalpha to this response.
Methods: Male and female mice, wild-type (WT) and PPARalpha-null (KO), were fed on diets rich in either saturated FA (SFA) or 18:3 n-3 (ALA). Lipid composition, mRNA levels and certain activities of key enzymes and major transcription factors were determined in the liver. WT mice were slightly affected by dietary FA. However, in WT female mice, but not in males, mRNA levels of PPARalpha-dependent genes (L-FABP, ACO) were higher in the mice fed on the ALA-rich diet. When compared to WT mice, KO female mice exhibited a decreased lipogenesis capacity (40% lower FAS, ACC, and SREBP-1c mRNA level), whereas KO males showed a decrease in peroxisomal beta-oxidation (activity and expression of ACO reduced by 20 and 40%, respectively). When compared to SFA-fed KO mice, steatosis was twice lower in KO mice fed on ALA, despite the absence of dietary effect on plasma TG, CPT1 and ACO activities, or ACC and FAS expression. Besides, in mice on the SFA diet, steatosis was alleviated in females, and CPT1 expression was up-regulated to a higher extent in females than in males (2.7- and 3.6-fold, respectively, as compared to the corresponding WT groups).
Conclusions: Our data suggests estrogen to modulate the regulation of hepatic lipid metabolic pathway by dietary fatty acids. Besides, PPARalpha invalidation resulted in unexpected regulations by ALA of its known targets and was compensated partly in females, which was therefore less sensitive to the detrimental effects of a SFA-rich diet.