Effects of dietary alpha- or gamma-linolenic acid on levels and fatty acid compositions of serum and hepatic lipids, and activity and mRNA abundance of 3-hydroxy-3-methylglutaryl CoA reductase in rats.
The effects of diets containing equal amounts of alpha (alpha)- or gamma (gamma)-linolenic acid on lipid metabolism were compared in rats. Four groups of male Wistar rats were given the diets containing 20% perilla/corn mixed oil or borage oil in the absence (PO- and BO-diets, respectively) or presence (CPO- and CBO-diets) of cholesterol for 20 days. The PO-diet yielded lower serum cholesterol than the BO-diet, although the difference was not observed between the CPO and CBO groups. The PO and CPO groups showed lower high-density lipoprotein cholesterol than the BO and CBO groups, respectively. A similar tendency was observed in serum phospholipids. The CPO-diet gave markedly lower hepatic triglycerides than the CBO-diet. The activity of hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase was much lower on the PO-diet than on the BO-diet. mRNA abundance of HMG-CoA reductase was lower in rats on the PO-diet than on the BO-diet, though there was no significant difference between the CPO and CBO groups. The present results indicate that alpha-linolenic acid exhibits a larger hypocholesterolemic effect than gamma-linolenic acid, and it may be displayed mainly through the repression of the activity and mRNA expression of HMG-CoA reductase.
D000818:Animals; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D004042:Dietary Fats, Unsaturated / Q000008:administration & dosage*; D005227:Fatty Acids / Q000032:analysis / Q000097:blood; D006903:Hydroxymethylglutaryl CoA Reductases / Q000235:genetics* / Q000378:metabolism*; D050356:Lipid Metabolism; D008055:Lipids / Q000097:blood / Q000737:chemistry; D008099:Liver / Q000737:chemistry / Q000378:metabolism; D008297:Male; D010743:Phospholipids / Q000097:blood / Q000737:chemistry / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017962:alpha-Linolenic Acid / Q000008:administration & dosage*; D017965:gamma-Linolenic Acid / Q000008:administration & dosage*