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T Magot

Publications and source records attributed to T Magot.

41 records · Page 3Linked to original sources
PubMed1983

[Effect of short- or medium-chain fatty acids on cholesterol dynamics in the rat].

The effects of a diet consisting of 10% medium-chain triglycerides (C8:0, C10:0) or 10% homogeneous triglycerides of 6- to 14-carbon chain saturated fatty acids on cholesterol turnover processes were studied in rats using the isotope equilibrium method. Cholesterol absorption was not significantly affected by the type of dietary fatty acid ingested. In contrast, lengthening of the fatty acid chain caused a moderate increase in the rates of cholesterol secretion (internal and external) and of transformation into bile acids. Thus, cholesterol synthesis was 80% higher in rats fed trimyristin (25.7 mg/day) than in those receiving tricaproin (14.6 mg/day). This increase seems essentially due to stimulated liver cholesterogenesis, as shown by in vivo incorporation of 14C-acetate.

Animals↗
PubMed1980

Effect of dietary long-chain fatty acids on the rates of cholesterol turnover processes, cholesterol origin and distribution in the rat intestinal lumen.

Adult male rats were fed a semi-purified diet containing 20 p. 100 of lard or homogeneous triglycerides (tripalmitin, tristearin, triolein, trierucin) for 4 months. The rates of the processes (absorption, synthesis, degradation into bile acids, fecal and urinary excretion) involved in cholesterol turnover were measured using the isotope equilibrium method. The absorption coefficient of dietary cholesterol attained 71 +/- 3 p. 100 in rats fed the lard diet. It was unchanged in rats eating the triolein (73 +/- 3 p. 100) or tripalmitin (75 +/- 4 p. 100) diet but was drastically reduced in those receiving trierucin (45 +/- 1 p. 100) or tristearin (34 +/- 1 p. 100). Some functional and topological aspects of cholesterol absorption are discussed. Four to 6 times more endogenous cholesterol was found in the intestinal lumen of rats fed trierucin than in that of rats receiving a normolipid diet. Micelle cholesterol increase was also proportionally less. There was no direct relationship between the quantity of cholesterol found in the micelles and that absorbed. Dietary cholesterol was absorbed in the second as well as in the first half of the intestine, while the proportions of micellar cholesterol decreased continuously from the jejunum to the ileum. The rates of fecal excretion and fecal external secretion were inversely correlated to the absorption coefficient of dietary cholesterol, as has been previously described. The internal secretion was stimulated two to threefold in rats fed tristearin (22.3 +/- 0.7 mg/d), tripalmitin (28.4 +/- 4.6 mg/d) and trierucin (33.2 +/- 2.8 mg/d) as compared to rats fed lard (12.5 +/- 0.6 mg/d) or triolein (14.4 +/- 1.2 mg/d). Feeding a tripalmitin or a trierucin diet greatly increased cholesterogenesis (probably in the liver), while tristearin stimulated non-hepatic cholesterogenesis. The variations in daily bile acid elimination may be seen as an adaptive parameter, modulating its rate according to the cholesterol supply (absorption and synthesis).

Animals↗
PubMed1976

In vivo study of free and esterified cholesterol turnover in various tissues of the rat.

Rats were infused for 3.5 to 10 hrs with either red cells or plasma previously labelled in vivo by [3H]-cholesterol. Cholesterol specific radioactivities were measured in plasma, HDL, LDL and VLDL, and various tissues. Red cell infusions led to a higher labelling of free than of esterified cholesterol in the plasma of infused rats. The opposite situation was observed following plasma infusion. Comparison of free and esterified cholesterol specific radioactivities in each tissue showed that esterified cholesterol was transferred from plasma to all the tissues, except the adrenals. Study of the ratios of cholesterol specific radioactivities from one experimental group to the other in each tissue, made it possible to demonstrate clearly the occurence of hydrolysis within all the studied tissues except 5 of them where its existence remains uncertain (lung, heart, kidney, tendon, muscle) and of esterification in 3 tissues (adrenal, liver lung). In addition, ratios of cholesterol radioactivities (free/ester) were found to be identical in plasma and in 4 tissues, where neither hydrolysis nor esterification were detected (heart, muscle, kidney, tendon). This finding is an argument in favor of a simultaneous transport of free and esterified cholesterol from plasma into these 4 tissues and suggests that the entire lipoprotein particles can penetrate these tissues, with no specificity of one special class. In adrenal, unlike all other tissues: 1) the turnover of esterified cholesterol was achieved mostly by hydrolysis and esterification in situ; 2) a preferential lipoprotein class (LDL) was responsible for the transport of free cholesterol from the plasma.

Adrenal Glands↗
PubMedDate not supplied

A multicompartmental model of cholesterol metabolism in rats.

A complete model of the cholesterol system was developed in the rat. It synthesizes several partial models previously developed under different isotopic conditions. It contains 16 compartments and 40 parameters. It specifically describes the intestine (mucosa and contents), liver and plasma cholesterol subsystems. The model was validated by the similarity between the simulated and experimental values in all the compartments during the 48 hours following the single introduction of an isotopic label in two different parts of the system (single ingestion of 14C-cholesterol, intravenous injection of red cells containing 3H-cholesterol). The similarity between the simulations and the experimental values was also observed up to 4 months following labelled cholesterol ingestion as well as under other different isotopic conditions for shorter periods. The parameter values identified and the resulting fluxes agree with the already published data.

Animals↗