The mechanism underlying the hypocholesterolemic effect of chronic fish oil feeding in rats is not due to increased excretion of dietary cholesterol

The role of the excretion of dietary cholesterol in the hypocholesterolaemic effect of chronic fish oil feeding in rats was investigated. The hepatic uptake and processing of [ 3H]cholesterol carried in chylomicrons derived from fish oil was studied in vivo in rats fed a low fat diet or a diet suppl...

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Published in:	Atherosclerosis Vol. 139; no. 2; pp. 253 - 263
Main Authors:	Bravo, Elena, Cantafora, Alfredo, DeLuca, Veronica, Tripodi, Marco, Avella, Michael, Botham, Kathleen M
Format:	Journal Article
Language:	English
Published:	Amsterdam Elsevier Ireland Ltd 01-08-1998 Elsevier
Subjects:	Animals Bile - metabolism Bile - physiology Bile acids Biliary lipid secretion Biological and medical sciences Cholesterol Cholesterol - blood Cholesterol, Dietary - urine Chylomicrons Chylomicrons - pharmacology Diet, Fat-Restricted Dietary Fats, Unsaturated - pharmacology Dietary n-3 polyunsaturated fatty acids Fish Oils - pharmacology Hepatic cholesterol metabolism Injections, Intravenous Lipid Metabolism Liver - enzymology Liver - metabolism Male Medical sciences Miscellaneous Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects) Rats Rats, Wistar RNA, Messenger - metabolism Triglycerides - blood Chylomicrons Dietary n-3 polyunsaturated fatty acids Bile acids Biliary lipid secretion Cholesterol Hepatic cholesterol metabolism Rat Secretion Liver Rodentia Supplemented diet Metabolism Fish oil Vertebrata Mammalia Chylomicron Diet therapy Bile acid Animal Mechanism of action
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Summary:	The role of the excretion of dietary cholesterol in the hypocholesterolaemic effect of chronic fish oil feeding in rats was investigated. The hepatic uptake and processing of [ 3H]cholesterol carried in chylomicrons derived from fish oil was studied in vivo in rats fed a low fat diet or a diet supplemented with fish oil for 21 days. In addition, the effects of the fish oil diet on cholesterol esterification, cholesteryl ester hydrolysis, bile acid synthesis and biliary lipid secretion were determined. In rats fed the fish oil as compared to the low fat diet, the uptake of [ 3H]cholesterol from the blood and its secretion into bile as bile acids was significantly slower, and this was entirely due to a decrease in the bile acid fraction. Biliary bile acid mass secretion was unchanged by fish oil feeding, while biliary cholesterol and phospholipid secretion was increased. No significant differences were observed either in the expression of mRNA for cholesterol 7 α hydroxylase or the secretion of bile acids into bile after 20 h biliary drainage between the fish oil and low fat diet groups, suggesting that bile acid synthesis is not affected. These results indicate that the access of chylomicron cholesterol to the hepatic substrate pool for bile acid formation is decreased in the fish oil fed rats, and this, together with its slower uptake from the blood, accounts for the retardation of its excretion via the bile. Thus, the hypocholesterolemic effect of dietary fish oil in rats is not due to more rapid metabolism of cholesterol originating from the diet.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0021-9150 1879-1484
DOI:	10.1016/S0021-9150(98)00075-6