Structure-Specific Effects of Short-Chain Fatty Acids on Plasma Cholesterol Concentration in Male Syrian Hamsters

Previous studies have shown that short-chain fatty acids (SCFAs) are capable of decreasing plasma cholesterol. However, the relative plasma-cholesterol-lowering activity of individual SCFAs and the underlying mechanisms by which SCFAs decrease plasma cholesterol remain largely unknown. The present study was done to compare the plasma-cholesterol-lowering potencies of four common SCFAs with 2-5 carbons and to investigate their interactions with gene expressions of key regulatory factors involved in cholesterol metabolism. For 6 weeks, five groups of male Golden hamsters were fed either a control high-cholesterol diet (HCD) or one of the four experimental HCDs containing 0.5 mol of acetate (Ac), propionate (Pr), butyrate (Bu), or valerate (Va) per kilogram of the diet. The results showed that Ac, Pr, and Bu significantly reduced plasma total cholesterol (TC) by 24, 18, and 17% (P < 0.05), respectively. All four SCFAs could decrease non-HDL cholesterol (non-HDL-C) and the non-HDL-C/HDL-C ratio. The addition of Ac, Pr, or Bu into the diet significantly promoted fecal excretion of bile acids by 121, 113, or 120% (P < 0.05), respectively, and upregulated the gene expressions of sterol-regulatory-element-binding protein 2 (SREBP2), low-density-lipoprotein receptor (LDLR), and cholesterol 7 alpha-hydroxylase (CYP7A1) in the liver. It was concluded that SCFAs with 2-4 carbons (Ac, Pr, and Bu) are more hypocholesterolemic than Va, which has 5 carbons, via enhancing fecal excretion of bile acids and promoting the hepatic uptake of cholesterol from the blood.