Dietary rhubarb (Rheum rhaponticum) stalk fibre stimulates cholesterol 7 alpha-hydroxylase gene expression and bile acid excretion in cholesterol-fed C57BL/6J mice.
Both experimental and clinical studies have indicated that a novel source of dietary fibre, produced from rhubarb (Rheum rhaponticum) stalks, is potentially hypolipidaemic. The present study, using C57BL/6J mice, was undertaken to examine if this fibre source affects cholesterol degradation. Mice were maintained on semi-purified diets containing 50 g rhubarb fibre or cellulose/kg with or without 5 g cholesterol/kg for 4 weeks. In cholesterol-supplemented mice, rhubarb fibre caused significant lowering of plasma cholesterol (-13%) and the hepatic concentrations of total cholesterol (-34%) and cholesteryl esters (-34%). In parallel to the reduction of hepatic cholesteryl ester content, animals fed on rhubarb fibre had significantly lower activity of acyl CoA: cholesterol acyltransferase (EC 2.3.1.26) than the mice maintained on a diet containing cellulose and cholesterol. Rhubarb-fibre feeding accelerated the faecal bile-acid loss and diminished the gall-bladder bile-acid pool in both the normal and the cholesterol-fed mice. The increase in the bile-acid excretion was positively correlated with an increased activity as well as mRNA abundance of cholesterol 7 alpha-hydroxylase (EC 1.14.13.17). The increased excretion of bile acids and induction of cholesterol 7 alpha-hydroxylase activity may account for the hypocholesterolaemic effect of rhubarb fibre.
Goel
V
V
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Canada.
Cheema
S K
SK
Agellon
L B
LB
Ooraikul
B
B
Basu
T K
TK
D000818:Animals; D001647:Bile Acids and Salts / Q000032:analysis / Q000378:metabolism*; D002482:Cellulose / Q000008:administration & dosage; D002784:Cholesterol / Q000032:analysis / Q000097:blood; D002790:Cholesterol 7-alpha-Hydroxylase / Q000235:genetics* / Q000378:metabolism; D002791:Cholesterol, Dietary / Q000378:metabolism*; D004043:Dietary Fiber / Q000008:administration & dosage* / Q000378:metabolism; D005243:Feces / Q000737:chemistry; D005704:Gallbladder / Q000378:metabolism; D015870:Gene Expression; D008099:Liver / Q000737:chemistry / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010946:Plants, Medicinal; D012333:RNA, Messenger / Q000032:analysis; D012250:Rheum; D002785:Sterol O-Acyltransferase / Q000378:metabolism
D001647:Bile Acids and Salts; D002791:Cholesterol, Dietary; D004043:Dietary Fiber; D012333:RNA, Messenger; D002482:Cellulose; D002784:Cholesterol; D002790:Cholesterol 7-alpha-Hydroxylase; D002785:Sterol O-Acyltransferase