scholarly journals Biodynamics of cholesterol and bile acids in the lithiasic hamster

1991 ◽  
Vol 66 (3) ◽  
pp. 479-492 ◽  
Author(s):  
J. Khallou ◽  
M. Riottot ◽  
M. Parquet ◽  
C. Verneau ◽  
C. Lutton
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Cholesterol Synthesis ◽  
Specific Activity ◽  
Plasma Cholesterol ◽  
Dietary Cholesterol ◽  
Young Male ◽  
Cholesterol Absorption ◽  
Biliary Cholesterol ◽  
Faecal Excretion

By using the isotopic equilibrium method in the young male Syrian hamster, the rates of cholesterol turnover processes, i.e. dietary cholesterol absorption, cholesterol synthesis, cholesterol excretion in the faeces and urine and cholesterol transformation into bile acids, were determined in the hamster receiving a control (C) or a lithogenic diet (L) for 7 weeks. At the end of this period the gall bladder of all animals in group L contained cholesterol gallstones. The coefficient of dietary cholesterol absorption was reduced by 26 %, cholesterol synthesis and cholesterol faecal excretion were twofold higher in group L than in group C. Bile acid content in the small intestine was diminished in group L, but bile acid composition was similar in the two groups. The increase in cholesterogenesis in lithiasic animals essentially took place in the liver. Bile acid biosynthesis did not significantly differ in the two groups, but represented only 35 % of total cholesterol input (dietary absorption + internal secretion) in group L ν. 52% in group C. Thus, in the lithiasic hamster, hepatic synthesis of cholesterol and bile acids are not coupled. The molar percentage of cholesterol in bile was twofold higher in group L than in group C but those of bile acids and of phospholipids were not modified. In the lithiasic hamster the specific activity of biliary cholesterol was similar to that in plasma and liver. Consequently, biliary cholesterol does not derive directly from cholesterol newly synthesized in the liver but from hepatic cholesterol rapidly exchangeable with plasma cholesterol.

scholarly journals Effects of dietary polychlorinated biphenyls on cholesterol catabolism in rats

1990 ◽  
Vol 64 (1) ◽  
pp. 161-169 ◽  
Author(s):  
Satoshi Nagaoka ◽  
Hitoshi Miyazaki ◽  
Yoritaka Aoyama ◽  
Akira Yoshida
Keyword(s):  
Polychlorinated Biphenyls ◽  
Bile Acids ◽  
Cholesterol Synthesis ◽  
Control Group ◽  
Hepatic Cholesterol ◽  
Biliary Cholesterol ◽  
Faecal Excretion ◽  
Hepatic Cholesterol Synthesis ◽  
Total Bile Acids

Dietary polychlorinated biphenyls (PCBs) caused hypercholesterolaemia in rats. The concentration and output of biliary cholesterol was significantly lower than that of the control group. Biliary output of total bile acids was significantly decreased in rats given the PCB-supplemented diet. Faecal excretion of total steroids (sum of neutral steroids and acidic steroids) was not significantly changed in rats given the PCB-supplemented diet. The present results indicate that dietary PCBs cause hypercholesterolaemia without modifying the faecal total steroids excretion. These results suggest that PCBs produce hyper-cholesterolaemia accompanied by changes in biliary or faecal excretion of bile acids and neutral steroids in addition to an increase in hepatic cholesterol synthesis.

Changes in Cholesterol Metabolism with Dietary Cholesterol in Children with Familial Hypercholesterolaemia

1979 ◽  
Vol 56 (4) ◽  
pp. 377-380 ◽  
Author(s):  
Gillian M. Martin ◽  
P. Nestel
Keyword(s):  
Bile Acid ◽  
Healthy Subjects ◽  
Cholesterol Synthesis ◽  
Familial Hypercholesterolaemia ◽  
Cholesterol Metabolism ◽  
Plasma Cholesterol ◽  
Dietary Cholesterol ◽  
Acid Synthesis ◽  
Bile Acid Synthesis ◽  
Healthy Children

1. Possible defects in cholesterol metabolism were sought in children with familial hypercholesterolaemia. 2. In nine affected children (eight heterozygotes and one homozygote) and in five healthy children, cholesterol synthesis and bile acid synthesis were determined from the excretion of steroids in the faeces during a low cholesterol diet. Cholesterol synthesis of 10·1 ± 4·4 mg day−1 kg−1 in the hypercholesterolaemic children was similar to that in these and other normal children. Mean bile acid synthesis of 4·0 ± 2·1 mg day−1 kg−1 also resembled normal values though three severely affected heterozygotes excreted substantially less. 3. The response to 4 weeks' additional 450 mg of dietary cholesterol/day led to variable changes in the plasma cholesterol and in the sterol balance. On average the affected children showed a rise in plasma cholesterol which resembled that in healthy subjects. The sterol balance fell in most, suggesting a reduction in cholesterol synthesis, which is the normal response to dietary cholesterol. 4. The response to dietary cholesterol was therefore at least qualitatively similar in the hypercholesterolaemic children to that reported in healthy subjects.

scholarly journals Dietary cholesterol absorption, and sterol and bile acid excretion in hypercholesterolemia-resistant white rabbits.

1990 ◽  
Vol 31 (11) ◽  
pp. 2019-2027
Author(s):  
ML Overturf ◽  
SA Smith ◽  
AM Gotto ◽  
JD Morrisett ◽  
T Tewson ◽  
...  
Keyword(s):  
Bile Acid ◽  
Dietary Cholesterol ◽  
Cholesterol Absorption ◽  
Acid Excretion ◽  
Bile Acid Excretion

scholarly journals Dietary Cholesterol Contained in Whole Eggs Is Not Well Absorbed and Does Not Acutely Affect Plasma Total Cholesterol Concentration in Men and Women: Results from 2 Randomized Controlled Crossover Studies

Nutrients ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1272 ◽  
Author(s):  
Jung Kim ◽  
Wayne Campbell
Keyword(s):  
Total Cholesterol ◽  
Plasma Cholesterol ◽  
Dietary Cholesterol ◽  
Cholesterol Absorption ◽  
Blood Cholesterol ◽  
Cholesterol Concentration ◽  
Total Cholesterol Concentration ◽  
Plasma Total Cholesterol ◽  
Crossover Studies ◽  
Whole Egg

Whole egg is a food source of dietary cholesterol and inconsistent research findings exist about the effect of dietary cholesterol from whole egg on blood cholesterol concentration. We assessed the effect of co-consuming cooked whole egg (CWE) on dietary cholesterol absorption from two randomized-crossover studies. For study 1, 16 men consumed raw vegetables with no egg, 75 g CWE, or 150 g CWE. For study 2, 17 women consumed cooked vegetables with no egg or 100 g CWE. Triacylglycerol-rich lipoprotein fractions (TRL) were isolated from collected blood. In study 1, total-cholesterol areas under the curve (AUC)0–10h in TRL were not different but triacylglycerol AUC0–10h in TRL was greater for 150 g CWE vs. 75 g CWE and no egg. Similarly, in study 2, total-cholesterol AUC0–10h in TRL was not different but triacylglycerol AUC0–10h in TRL was greater for 100 g CWE vs. no egg. In both studies, whole egg consumption did not affect plasma total-cholesterol AUC0–10h, while triacylglycerol AUC0–10h was increased. These results suggest that the dietary cholesterol in whole egg was not well absorbed, which may provide mechanistic insight for why it does not acutely influence plasma total-cholesterol concentration and is not associated with longer-term plasma cholesterol control.

Bile secretion during experimental hyperthyroidism in the dog

1960 ◽  
Vol 199 (5) ◽  
pp. 893-897 ◽  
Author(s):  
Joseph H. Gans
Keyword(s):  
Bile Acids ◽  
Plasma Cholesterol ◽  
Bile Secretion ◽  
The State ◽  
Biliary Cholesterol ◽  
Thyroid Activity ◽  
Experimental Hyperthyroidism ◽  
Significant Change

Experimental hyperthyroidism in the dog was accompanied by a significant decrease in the enterohepatic content of bile acids with no significant change in biliary cholesterol output. Plasma cholesterol concentrations decreased consistently in all hyperthyroid dogs. Alterations in the diet were followed by marked changes in bile secretion both in the euthyroid and hyperthyroid dogs. The euthyroid dogs given a diet supplemented with protein and cholesterol secreted greater amounts of cholesterol and bile acids into bile. Hyperthyroidism, induced in dogs given the supplemented diet, was associated with a decrease in the biliary output of both cholesterol and bile acids when compared with the controls given the supplemented unchanged. Changes in the secretion of biliary steroids and sterols during experimental hyperthyroidism in the dog may be the result of a disproportionate increase in the rate of the oxidation of acetate. Confirming earlier investigations in thyroidectomized dogs, dietary constituents may influence plasma cholesterol concentrations in the dog regardless of the state of thyroid activity.

Transcriptional regulation of hepatic sterol 27-hydroxylase by bile acids

1996 ◽  
Vol 270 (4) ◽  
pp. G646-G652 ◽  
Author(s):  
Z. R. Vlahcevic ◽  
S. K. Jairath ◽  
D. M. Heuman ◽  
R. T. Stravitz ◽  
P. B. Hylemon ◽  
...  
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Specific Activity ◽  
Feedback Regulation ◽  
Initial Step ◽  
Mrna Levels ◽  
Acid Biosynthesis ◽  
Negative Feedback Regulation ◽  
Study Objective ◽  
Specific Activities

The study objective was to determine whether and to what extent sterol 27-hydroxylase, the initial step in the "acidic" pathway of bile acid biosynthesis, is regulated by bile acids. Rats were fed diets supplemented with cholestyramine (CT, 5%), cholate (CA, 1%), chenodeoxycholate (CDCA, 1%), or deoxycholate (DCA, 0.25%). When compared with paired controls, sterol 27-hydroxylase and cholesterol 7 alpha-hydroxylase specific activities increased after CT administration by 188 +/- 20% (P < 0.05) and 415 +/- 36% (P < 0.01), respectively. Similarly, mRNA levels increased by 159 +/- 14% (P < 0.05) and 311 +/- 106% (P < 0.05), respectively. Feeding CA, CDCA, or DCA decreased sterol 27-hydroxylase specific activity to 57 +/- 6, 61 +/- 8, and 74 +/- 8% of controls, respectively (P < 0.05). By comparison, the specific activity of cholesterol 7 alpha-hydroxylase decreased to 46 +/- 7 , 32 +/- 10, and 26 +/- 8% (P = 0.001). mRNA levels and transcriptional activities for sterol 27-hydroxylase and cholesterol 7 alpha-hydroxylase transcriptional activity were changed to the same extent as the specific activities after CT or bile acid feeding. We conclude that sterol 27-hydroxylase and cholesterol 7 alpha-hydroxylase are subject to negative feedback regulation by hydrophobic bile acids at the level of transcription. However, the responses of sterol 27-hydroxylase to manipulation of the bile acid pool are less prominent than those of cholesterol 7 alpha-hydroxylase. During the diurnal cycle the specific activities of sterol 27-hydroxylase and cholesterol 7 alpha-hydroxylase changed in tandem, suggesting that both may be under control of glucocorticoids.

High plasma cholesterol in drug-induced cholestasis is associated with enhanced hepatic cholesterol synthesis

1999 ◽  
Vol 276 (5) ◽  
pp. G1165-G1173 ◽  
Author(s):  
Jeffrey W. Chisholm ◽  
Patrick Nation ◽  
Peter J. Dolphin ◽  
Luis B. Agellon
Keyword(s):  
Bile Acids ◽  
Cholesterol Synthesis ◽  
Cell Membranes ◽  
Reductase Activity ◽  
Plasma Cholesterol ◽  
Hepatic Cell ◽  
Plasma Lipoproteins ◽  
Liver Cholesterol ◽  
Hepatic Cholesterol ◽  
Hepatic Cholesterol Synthesis

In α-naphthylisothiocyanate-treated mice, plasma phospholipid (PL) levels were elevated 10- and 13-fold at 48 and 168 h, respectively, whereas free cholesterol (FC) levels increased between 48 h (17-fold) and 168 h (39-fold). Nearly all of these lipids were localized to lipoprotein X-like particles in the low-density lipoprotein density range. The PL fatty acyl composition was indicative of biliary origin. Liver cholesterol and PL content were near normal at all time points. Hepatic hydroxymethylglutaryl CoA reductase activity was increased sixfold at 48 h, and cholesterol 7α-hydroxylase activity was decreased by ∼70% between 24 and 72 h. These findings suggest a metabolic basis for the appearance of abnormal plasma lipoproteins during cholestasis. Initially, PL and bile acids appear in plasma where they serve to promote the efflux of cholesterol from hepatic cell membranes. Hepatic cholesterol synthesis is then likely stimulated in the response to the depletion of hepatic cell membranes of cholesterol. We speculate that the enhanced synthesis of cholesterol and impaired conversion to bile acids, particularly during the early phase of drug response, contribute to the accumulation of FC in the plasma.

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