Diets rich in polyunsaturated fatty acids: effect on hepatic metabolism in rats.
OBJECTIVE
We investigated the effect of diets rich in omega-6 and omega-3 fatty acids on hepatic metabolism.


METHODS
Male Wistar rats, just weaned, were fed ad libitum for 8 wk with one of the following diets: rat chow (C), rat chow containing 15% (w/w) soybean oil (S), rat chow containing 15% (w/w) fish oil (F), and rat chow containing 15% soy bean and fish oil (SF; 5:1, w/w). Casein was added to the fatty diets to achieve the same content of protein (20%) as the control chow. The rats were killed by decapitation, and the hepatic tissue was removed and weighed. Tissue lipid, glycogen, and protein content, in vivo lipogenesis rate, and adenosine triphosphate citrate lyase and malic enzyme activities were evaluated. Plasma total lipids, triacylglycerol, and cholesterol concentrations were assessed.


RESULTS
Body weight gain was higher in F and SF than in C and S rats. Liver weight, lipid content, and lipogenesis rate increased in F and SF rats, although adenosine triphosphate citrate lyase activity decreased. Glycogen concentration decreased in S, F, and SF rats compared with C rats. Plasma total lipids and triacylglycerol concentrations were lower in F and SF than in C rats. Total and high-density lipoprotein cholesterol (HDL-C) plasma levels decreased in F rats, with maintenance of the total:HDL-C ratio. In SF rats, an increase in HDL-C led to a lower total:HDL-C ratio.


CONCLUSIONS
These results indicated that an enrichment of the diet with omega-3 polyunsaturated fatty acids produces hypolipidemia but may cause changes in liver metabolism that favor lipid deposition. They also suggested that the addition of a small amount of eicosapentaenoic and docosahexaenoic polyunsaturated fatty acids to an omega-6-rich diet further improve the circulating lipid profile, in comparison with an omega-3-rich diet, but it does not prevent excess liver lipid accumulation.
Gaíva
Maria Helena
MH
Department of Physiology, Division of Neurophysiology and Endocrine Physiology, São Paulo Federal University, São Paulo, Brazil.
Couto
Rosany C
RC
Oyama
Lila M
LM
Couto
Gilmar E C
GE
Silveira
Vera L F
VL
Ribeiro
Eliane B
EB
Nascimento
Cláudia M O
CM
D001275:ATP Citrate (pro-S)-Lyase / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D001835:Body Weight / Q000187:drug effects*; D002784:Cholesterol / Q000097:blood / Q000378:metabolism; D004032:Diet; D004042:Dietary Fats, Unsaturated / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D050356:Lipid Metabolism; D008099:Liver / Q000378:metabolism*; D008112:Liver Glycogen / Q000378:metabolism; D008291:Malate Dehydrogenase / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009929:Organ Size / Q000187:drug effects; D011506:Proteins / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014280:Triglycerides / Q000097:blood / Q000378:metabolism
D004042:Dietary Fats, Unsaturated; D005231:Fatty Acids, Unsaturated; D008112:Liver Glycogen; D011506:Proteins; D014280:Triglycerides; D002784:Cholesterol; D008291:Malate Dehydrogenase; D001275:ATP Citrate (pro-S)-Lyase